CN109687716A - A kind of controlled resonant converter of series-parallel bumpless transfer - Google Patents

Abstract

The present invention provides a kind of controlled resonant converters of series-parallel bumpless transfer, belong to power electronics field, including DC power supply, switching circuit, resonance circuit, rectification circuit and the filter circuit being sequentially connected electrically；Switching circuit receives peripheral control unit control；Resonance circuit includes the transformer module for being connected to the resonance modules of switching circuit and connecting with resonance modules；Transformer module includes N number of transformer, and resonance modules include N group resonance group, and switching circuit includes N group switch module, and N >=2 and N are even number；Rectification circuit includes the first rectification module, the second rectification module and third rectification module.Solve the problems, such as that current controlled resonant converter constant power output voltage range is limited, output voltage range is discontinuous, at high cost, volume is big, cannot export no-voltage.

Description

A resonant converter with seamless series-parallel conversion

technical field

The invention belongs to the technical field of power electronics, and in particular relates to a series-parallel seamless conversion resonant converter.

Background technique

At present, common resonant converters include series, parallel, and series-parallel resonant converters. Due to their simple circuit topology and their ability to achieve soft switching over the full load range, resonant converters are widely used in state-of-the-art power supplies that provide the highest power density and efficiency. Although the resonant converter has many advantages such as soft switching of switching devices, low switching loss, high efficiency, and superior EMI (Electromagnetic Interference) performance compared to hard switching, the defects are still obvious, as shown in Figure 1. The current basic resonant converter is taken as an example. The output voltage of the resonant converter is usually adjusted by adjusting the operating frequency. Due to the range of the frequency to be adjusted and the gain characteristics of the resonant converter, the adjustment range is very limited, which is only the rated voltage. Between 0.8 times and 1.2 times; let the output voltage Vo of the transformer T1 be the rated voltage under the condition of the resonant frequency.

In order to solve the above problems, as shown in Figure 2, a common solution in the industry is to use a relay to switch the series-parallel mode between two transformers, so as to achieve a wide range of output constant power conversion. Assuming that the parameters of the two transformers are the same, without considering that the output voltage may be adjusted near the rated voltage, when the relays RY3 are closed and RY1 and RY2 are disconnected, the two transformers work in series mode, then the output voltage of this topology is Rated voltage (this topology is the resonant converter); when the relays RY1 and RY2 are closed and RY3 is open, and the two transformers work in parallel mode, the output voltage of this topology is 1/2 times the rated voltage, and the output power remains constant (not reduced). Considering that the output voltage of the resonant converter may be adjusted near the rated voltage by adjusting the frequency, that is, the adjustment range of the single resonant converter is between 0.8 times and 1.2 times the rated voltage according to the foregoing, the resonance shown in Figure 2 The output constant power voltage regulation range of the converter is 0.4 times to 1.2 times of the rated voltage. It can be seen that the output voltage range is very wide, but because the resonant converter only performs simple series-parallel switching through relays, its constant power range is not continuous. (for example, in the range of 0.6-0.8 times the rated voltage, it is impossible to achieve constant power output or even the output voltage in this range), and the relay is large and expensive, which leads to the high cost and large volume of the entire resonant converter. The problem.

SUMMARY OF THE INVENTION

In order to overcome the deficiencies of the prior art, the purpose of the present invention is to provide a resonant converter with seamless series-parallel conversion, which solves the problem that although the current resonant converter can expand its output voltage range, the entire resonant converter has high cost and large volume. question.

The purpose of the present invention adopts following technical scheme to realize:

A series-parallel seamless conversion resonant converter includes a DC power supply, a switch circuit, a resonant circuit, a rectifier circuit and a filter circuit that are electrically connected in sequence; the switch circuit is controlled by an external controller; the resonant circuit includes a resonant module and a resonant circuit. Transformer module, the transformer module includes N transformers, the resonance module includes N groups of resonance groups, the switch circuit includes N groups of switch modules, N≥2 and N is an even number; the rectifier circuit includes a first rectifier module, The second rectifier module and the third rectifier module; wherein,

The primary side homonymic end of the transformer is connected to one end corresponding to the switch module through the corresponding resonance group, and the primary side non-homonymous end of the transformer is connected to the other end corresponding to the switch module;

If N=2, the same-named terminal on the secondary side of the first transformer is connected to the midpoint of the bridge arm of the first rectifier module, and the non-identical terminal on the secondary side of the first transformer is connected to the second terminal. The secondary side of the transformer is connected to the same name terminal, the secondary side non-homonymous terminal of the second transformer is connected to the midpoint of the bridge arm of the second rectifier module, and the secondary side non-homonymous terminal of the first transformer is connected. connected to the midpoint of the bridge arm of the third rectifier module; or

If N>2 and N is an even number, the same-named terminal on the secondary side of the first transformer is connected to the midpoint of the bridge arm of the first rectifier module, and the non-identical terminal on the secondary side of the first transformer is connected to the midpoint of the bridge arm of the first rectifier module. The secondary side of the second transformer is connected to the same name terminal, the secondary side non-homonymous terminal of the adjacent transformer is connected to the secondary side homonymic terminal, and the secondary side non-homonymous terminal of the Nth transformer is connected to the secondary side. The midpoint of the bridge arm of the second rectifier module, the N/2 th non-same-named end of the secondary side of the transformer is connected to the midpoint of the bridge arm of the third rectifier module.

Based on the above resonant converter, when N=2, switching the switches in the switch circuit by the external controller can make the secondary side of the two transformers seamlessly switch between series or parallel modes. When the two transformers work in series mode, the output voltage of the resonant converter is the rated voltage; when the two transformers work in parallel mode, the output voltage of the resonant converter is 1/2 of the rated voltage; when N>2 and N is an even number, pass The external controller switches the switches in the switch circuit to make the secondary side of the first transformer to the N/2th transformer and the 1+(N/2) transformer to the Nth transformer between series or parallel mode Seamless conversion, when the first transformer to the N/2 transformer and the 1+(N/2) transformer to the Nth transformer work in series mode, the output voltage of the resonant converter is higher than the rated voltage; When the first transformer to the N/2 transformer and the 1+(N/2) transformer to the Nth transformer work in parallel mode, the output voltage of the resonant converter is lower than 1/2 of the rated voltage; In this way, it can not only expand the output voltage range of the current resonant converter, but also realize continuous constant power voltage range adjustment, and reduce the number of relays, reduce the cost of the current resonant converter, reduce the volume of the current resonant converter, and even output zero. Voltage.

Optionally, if N=2, a relay is provided between the non-identical terminal on the secondary side of the first transformer and the midpoint of the bridge arm of the third rectifier module; or

If N>2 and N is an even number, a relay is provided between the non-identical terminal on the secondary side of the N/2th transformer and the midpoint of the bridge arm of the third rectifier module. Based on adding a relay in the resonant converter, the output zero voltage of the resonant converter can be realized.

Optionally, the DC power supply includes a single DC power supply or multiple DC power supplies or multiple positive and negative DC power supplies.

Optionally, the switch module includes a half-bridge switch module or a full-bridge switch module. The half-bridge switch module has low cost, while the full-bridge switch module is suitable for higher power applications.

Optionally, the half-bridge switch module includes two switch tubes; the first end of the switch tube is connected to the output end of the DC power supply, and the second end of the switch tube is connected to the corresponding resonance The second end of one switch tube is connected to the first end of the other switch tube; the second end of the other switch tube is connected to the input end of the DC power supply, and the other switch tube The second end of the switch is grounded, and the second end of the other switch tube is also connected to the non-identical end of the primary side of the corresponding transformer.

Optionally, the half-bridge switch module includes a first switch, a second switch, a third switch, a fourth switch, a first capacitor, a second capacitor, a first diode, and a second diode ; The first end of the first switch tube is connected to the output end of the DC power supply, the second end of the first switch tube is connected to the first end of the second switch tube, and the second end of the second switch tube is connected to the first end of the second switch tube. The two ends are connected to the first end of the third switch tube, the second end of the third switch tube is connected to the first end of the fourth switch tube, and the second end of the fourth switch tube is connected to the DC The input end of the power supply, the second end of the fourth switch tube is grounded; one end of the first capacitor is connected to the first end of the first switch tube, and the other end of the first capacitor is connected to the second capacitor connected to the second end of the fourth switch tube; the cathode of the first diode is connected to the second end of the first switch tube, and the anode of the first diode is connected to the other end of the first capacitor one end, the anode of the first diode is connected to the cathode of the second diode, the anode of the second diode is connected to the second end of the third switch tube; The second terminal is connected to the corresponding resonance group, and the anode of the first diode is also connected to the non-identical terminal corresponding to the primary side of the transformer.

Optionally, the full-bridge switch module includes a first switch tube, a second switch tube, a third switch tube and a fourth switch tube; the first end of the first switch tube is connected to the output end of the DC power supply, The second end of the first switch tube is connected to the first end of the second switch tube, the second end of the second switch tube is connected to the input end of the DC power supply, and the second end of the second switch tube is connected to the input end of the DC power supply. The terminal is grounded; the first end of the third switch tube is connected to the first end of the first switch tube, the second end of the third switch tube is connected to the first end of the fourth switch tube, and the first end of the third switch tube is connected to the first end of the fourth switch tube. The second end of the four switch tubes is connected to the second end of the second switch tube; the second end of the first switch tube is connected to the resonance group, and the second end of the third switch tube is connected to the corresponding The primary side of the transformer is not the same name terminal.

Optionally, the full-bridge switch module includes a first switch, a second switch, a third switch, a fourth switch, a fifth switch, a sixth switch, a first capacitor, a second capacitor, a first a diode and a second diode; the first end of the first switch tube is connected to the output end of the DC power supply, and the second end of the first switch tube is connected to the first end of the second switch tube terminal, the second end of the second switch tube is connected to the first end of the third switch tube, the second end of the third switch tube is connected to the first end of the fourth switch tube, and the fourth switch tube is connected to the first end of the fourth switch tube. The second end of the switch tube is connected to the input end of the DC power supply, the second end of the fourth switch tube is grounded; the first end of the fifth switch tube is connected to the first end of the first switch tube, so The second end of the fifth switch tube is connected to the first end of the sixth switch tube, the second end of the sixth switch tube is connected to the second end of the fourth switch tube; one end of the first capacitor connected to the first end of the first switch tube, the other end of the first capacitor is connected to the second end of the fourth switch tube through the second capacitor; the cathode of the first diode is connected to the The second end of the first switch tube, the anode of the first diode is connected to the other end of the first capacitor, the anode of the first diode is also connected to the cathode of the second diode, so The anode of the second diode is connected to the second end of the third switch tube; the second end of the fifth switch tube is connected to the corresponding resonance group, and the second end of the second switch tube is connected to the corresponding The primary side of the transformer is not the same name terminal.

Optionally, the full-bridge switch module includes a first switch, a second switch, a third switch, a fourth switch, a fifth switch, a sixth switch, a seventh switch, and an eighth switch , a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a first diode, a second diode, a third diode and a fourth diode; the first The terminal is connected to the output terminal of the DC power supply, the second terminal of the first switch tube is connected to the first terminal of the second switch tube, and the second terminal of the second switch tube is connected to the third switch tube. the first end, the second end of the third switch tube is connected to the first end of the fourth switch tube, the second end of the fourth switch tube is connected to the input end of the DC power supply, the fourth switch tube The second end of the tube is grounded; one end of the first capacitor is connected to the first end of the first switch tube, and the other end of the first capacitor is connected to the second end of the fourth switch tube through the second capacitor terminal; the cathode of the first diode is connected to the second end of the first switch tube, the anode of the first diode is connected to the other end of the first capacitor, and the anode of the first diode is connected to the other end of the first capacitor. The positive electrode is also connected to the negative electrode of the second diode, the positive electrode of the second diode is connected to the second end of the third switch tube, and the second end of the second switch tube is connected to the corresponding transformer. Primary side non-homonymous end;

The first end of the fifth switch tube is connected to the first end of the first switch tube, the second end of the fifth switch tube is connected to the first end of the sixth switch tube, and the sixth switch tube The second end of the seventh switch tube is connected to the first end of the seventh switch tube, the second end of the seventh switch tube is connected to the first end of the eighth switch tube, and the second end of the eighth switch tube is connected to the the second end of the fourth switch tube; one end of the third capacitor is connected to the first end of the fifth switch tube, and the other end of the third capacitor is connected to the eighth switch tube through the fourth capacitor the second end of the third diode; the cathode of the third diode is connected to the second end of the fifth switch tube, the anode of the third diode is connected to the other end of the third capacitor, the third and second The anode of the pole tube is connected to the cathode of the fourth diode, the anode of the fourth diode is connected to the second end of the seventh switch tube, and the second end of the sixth switch tube is connected to the corresponding resonance group.

Optionally, the first rectifier module includes a first diode and a second diode; the second rectifier module includes a third diode and a fourth diode; the third rectifier module includes a Five diodes and a sixth diode; the first diode is connected in series with the second diode, the third diode is connected in series with the fourth diode, and the fifth and second diodes are connected in series with the fourth diode. A pole tube is connected in series with the sixth diode, the cathodes of the first diode, the third diode and the fifth diode are connected to each other, the second diode, the The anodes of the fourth diode and the sixth diode are connected to each other, the anode of the second diode is grounded; the anode of the first diode is connected to the secondary side of the first transformer with the same name terminal, the anode of the third diode is connected to the secondary side non-identical terminal of the N/2th transformer, and the anode of the fifth diode is connected to the secondary side non-identical terminal of the Nth transformer end.

Optionally, the switch tube includes a field effect transistor or an insulated gate bipolar transistor, and at least one diode from the first diode to the sixth diode is replaced by a field effect transistor or an insulated gate bipolar transistor. .

Optionally, the relay is replaced by a bidirectional switch.

Optionally, the resonant group includes a resonant inductance, an excitation inductance, and a resonant capacitor; the primary side of the transformer is connected to one end of the switch module through the resonant capacitor and the resonant inductance, and the primary side of the transformer is not the same name. connected to the other end of the switch module, and the excitation inductance is further provided between the two ends of the primary side of the transformer; or

The primary-side homonymic end of the transformer is connected to one end of the switch module, the primary-side non-homonymous end of the transformer is connected to the other end of the switch module via the resonant capacitor and the resonant inductance, and the transformer's The excitation inductance is provided between both ends of the primary side.

Optionally, the filter circuit includes a filter capacitor, one end of the filter capacitor is connected to the cathode of the fifth diode, and the other end of the filter capacitor is connected to the anode of the sixth diode.

Compared with the prior art, the beneficial effects of the present invention are:

Based on the above resonant converter, when the relay is closed, the external controller switches the switches in the switch circuit to seamlessly (continuously) convert the transformers on both sides connected to the same end of the relay between series or parallel modes, thereby making the resonant conversion The device can output the voltage of the preset range near the rated voltage, and can also output the voltage below 1/2 times the rated voltage, and the voltage range is continuously adjustable; when the relay is disconnected, if the transformers on both sides connected to the same end of the relay If the polarity of the total voltage on the secondary side is reversed, the output voltage of the resonant converter is zero voltage, thus expanding the output voltage range of the current resonant converter, especially the constant power voltage adjustment range, which not only realizes continuous voltage conversion, but also reduces the number of relays. , thereby reducing the cost of the current resonant converter and reducing the volume of the current resonant converter.

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

Description of drawings

1 is a schematic circuit diagram of a current basic resonant converter provided by the present invention;

Fig. 2 is the circuit schematic diagram of the present resonant converter provided by the present invention;

3 is a schematic structural diagram of a resonant converter provided in Embodiment 1 of the present invention;

4 is a schematic structural diagram 1 of a partial resonant converter provided in Embodiment 1 of the present invention;

5 is a second schematic structural diagram of a partial resonant converter provided in Embodiment 1 of the present invention;

6 is a schematic structural diagram 1 of a partial resonant converter provided in Embodiment 1 of the present invention;

7 is a second schematic structural diagram of a partial resonant converter provided in Embodiment 1 of the present invention;

FIG. 8 is a first schematic circuit diagram of a half-bridge switch module according to Embodiment 1 of the present invention;

FIG. 9 is a second schematic circuit diagram of a half-bridge switch module according to Embodiment 1 of the present invention;

FIG. 10 is a schematic circuit diagram 1 of a resonant converter provided in Embodiment 1 of the present invention;

11 is a second schematic circuit diagram of the resonant converter provided in Embodiment 1 of the present invention;

12 is a third circuit schematic diagram of the resonant converter provided in Embodiment 1 of the present invention;

13 is a first schematic circuit diagram of a full-bridge switch module according to Embodiment 2 of the present invention;

14 is a second schematic circuit diagram of a full-bridge switch module according to Embodiment 2 of the present invention;

15 is a third circuit schematic diagram of a full-bridge switch module provided in Embodiment 2 of the present invention;

FIG. 16 is a schematic circuit diagram of a resonant converter provided in Embodiment 2 of the present invention.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be noted that, on the premise of no conflict, the embodiments or technical features described below can be combined arbitrarily to form new embodiments. .

Example 1

In order to solve the problems that the current resonant converter has a limited constant power output voltage range, discontinuous output voltage range, high cost, large volume, and inability to output zero voltage, as shown in FIG. 3, this embodiment provides a series-parallel seamless conversion The resonant converter includes a DC power supply, a switch circuit, a resonant circuit, a rectifier circuit and a filter circuit that are electrically connected in sequence, and the output end of the filter circuit is also connected to a load; the switch circuit is controlled by an external controller; the resonant circuit includes a resonant module and a transformer module The transformer module includes N transformers, the resonance module includes N groups of resonance groups, the switch circuit includes N groups of switch modules, N≥2 and N is an even number; the rectifier circuit includes a first rectifier module, a second rectifier module and a third rectifier module; in,

The primary side homonymic end of the transformer is connected to one end of the corresponding switch module through the corresponding resonance group, and the non-homonymous end of the primary side of the transformer is connected to the other end of the corresponding switch module;

If N=2, the same-name terminal on the secondary side of the first transformer is connected to the midpoint of the bridge arm of the first rectifier module, and the non-identical terminal on the secondary side of the first transformer is connected with the same-name terminal on the secondary side of the second transformer. connected, the non-same-named end of the secondary side of the second transformer is connected to the midpoint of the bridge arm of the second rectifier module, and the non-same-named end of the secondary side of the first transformer is connected to the midpoint of the bridge arm of the third rectifier module;

If N>2 and N is an even number, the same-named terminal on the secondary side of the first transformer is connected to the midpoint of the bridge arm of the first rectifier module, and the non-identical terminal on the secondary side of the first transformer is connected to the secondary side of the second transformer. The same-name terminal on the secondary side is connected to the same-name terminal on the secondary side of the adjacent transformer. The non-identical terminals of the secondary sides of the two transformers are connected to the midpoint of the bridge arm of the third rectifier module.

Based on the above resonant converter, when N=2, the transformer module includes two transformers, and the secondary side of the two transformers can be seamlessly converted between series or parallel modes by switching the switches in the switch circuit by an external controller. When the two transformers work in series mode, the output voltage of the resonant converter is the rated voltage; when the two transformers work in parallel mode, the output voltage of the resonant converter is 1/2 of the rated voltage;

When N>2 and N is an even number, the transformer module includes N transformers, and the switch tube in the switch circuit can be switched by the external controller to make the first transformer to the N/2 transformer and the first + (N/2) Transformers to Nth transformers switch seamlessly between series or parallel mode, when 1st transformer to N/2th transformer and 1+(N/2)th transformer to Nth transformer work in series mode When the output voltage of the resonant converter is higher than the rated voltage; when the first transformer to the N/2th transformer and the 1+(N/2) transformer to the Nth transformer work in parallel mode, the resonance The output voltage of the converter is lower than 1/2 of the rated voltage. Thereby expanding the continuously adjustable output voltage range of the current resonant converter, and reducing the number of relays, thereby reducing the cost of the current resonant converter, reducing the volume of the current resonant converter, and also achieving an output lower than 1/2 times. rated voltage.

In addition, based on changing the connection mode between the transformer module and the rectifier circuit in the resonant converter, when N=2, switching the switch tube in the switch circuit through the external controller can make the secondary side of the two transformers in series or parallel mode. When the two transformers work in series mode, the output voltage becomes larger, while the output current becomes smaller, the output power remains unchanged; when the two transformers work in parallel mode, the output voltage becomes smaller, and the output current becomes smaller. The output power remains unchanged; when N>2 and N is an even number, the switch tube in the switch circuit can be switched by the external controller to make the first transformer to the N/2 transformer and the 1+(N/ 2) The secondary side of the transformer to the Nth transformer seamlessly transitions between series or parallel modes, when the first transformer to the N/2th transformer and the 1+(N/2)th transformer to the Nth transformer When the first transformer works in series mode, the output voltage becomes larger and the output current becomes smaller, so the output power remains unchanged; when the first transformer to the N/2 transformer and the 1+(N/2) transformer to the N transformers work in parallel mode, the output voltage becomes smaller, and the output current becomes larger, and the output power remains unchanged; thus, it is suitable for the occasion of constant power.

When the transformer module includes two transformers, the resonant module includes two groups of resonant groups, and the switch circuit includes two groups of switch modules; as shown in Figure 4, the same-named terminal on the primary side of the transformer T1 is connected to the first group of switches through the first group of resonant groups One end of the module, the non-homonymous end of the primary side of the transformer T1 is connected to the other end of the first group of switch modules, the primary side of the transformer T2 is connected to one end of the second group of switch modules through the second group of resonance groups, and the primary side of the transformer T2 is connected to one end of the module. The side non-homonymous end is connected to the other end of the second group of switch modules; the secondary side homonymic end of the transformer T1 is connected to the midpoint of the bridge arm of the first rectifier module, and the secondary side non-homonymous end of the transformer T1 is connected to the third rectifier module The non-homonymous end of the secondary side of the transformer T1 is also connected to the secondary side homonymic end of the transformer T2, and the secondary side non-homonymous end of the transformer T2 is connected to the bridge arm midpoint of the second rectifier module.

Based on the transformer module including the transformer T1 and the transformer T2, the switch tube in the switch circuit can be switched by the external controller to make the transformer T1 and the transformer T2 seamlessly switch between the series or parallel mode. When the transformer T1 and the transformer T2 work in the series mode , the output voltage of the resonant converter is the rated voltage; when the transformer T1 and the transformer T2 work in parallel mode, that is, when the resonant converter works in parallel mode, the output voltage of the resonant converter is 1/2 times the rated voltage; Therefore, it not only expands its constant power output voltage range and continuous voltage regulation capability, but also reduces the number of relays, thereby reducing the cost of the entire resonant converter and reducing the volume of the entire resonant converter.

When the transformer module includes N transformers, the resonance module includes N groups of resonance groups, and the switch circuit includes N groups of switch modules, where N>2 and N is an even number; as shown in FIG. 5 , the transformer module includes transformer T1, transformer T2, Transformers T3…..transformers TN, the primary side homonymous terminals of transformers T1, T2…TN are respectively connected to one end of the corresponding switch module through the corresponding resonance group, and the primary side non-homonymous terminals of transformers T1, T2…TN are respectively connected to the other end of the corresponding switch module; the secondary side homonymic end of transformer T1 is connected to the midpoint of the bridge arm of the first rectifier module, the secondary side non homonymic end of transformer T1 is connected to the secondary side homonymic end of transformer T2, and the The non-homonymous terminal on the secondary side is connected to the secondary-side homonymic terminal of the transformer T3, and so on, until the secondary-side non-homonymous terminal of the transformer TN-1 is connected to the secondary-side homonymic terminal of the transformer TN, and the secondary side of the transformer TN is not the same name. The terminal is connected to the midpoint of the bridge arm of the second rectifier module, and the non-identical terminal of the secondary side of the transformer TN/2 is connected to the midpoint of the bridge arm of the third rectifier module.

Based on the above resonant converter, switching the switches in the internal switching circuit of the resonant converter by an external controller can make the transformers T1 to T2/N and the transformers T1+(N/2) to TN seamlessly switch between series or parallel modes, When transformers T1 to T2/N and transformers T1+(N/2) to TN work in series mode, the output voltage of the resonant converter is higher than the rated voltage; when transformers T1 to T2/N and transformers T1+(N/2) When working in parallel mode to TN, the output voltage of the resonant converter is lower than 1/2 times the rated voltage; thus not only expands its constant power output voltage range and continuous voltage regulation capability, but also reduces the number of relays and reduces the entire resonant converter. The cost of the converter is reduced, and the volume of the entire resonant converter is reduced.

Further, as shown in FIG. 6 , if N=2, a relay is provided between the non-identical end of the secondary side of the first transformer T1 and the midpoint of the bridge arm of the third rectifier module; or

As shown in FIG. 7 , if N>2 and N is an even number, a relay is provided between the non-identical terminal on the secondary side of the N/2th transformer TN/2 and the midpoint of the bridge arm of the third rectifier module.

Based on the resonant transformer, when N=2, the transformer module includes two transformers. When the relay RY1 is turned off, if the voltages on the secondary side of the transformer T1 and the transformer T2 have opposite polarities and the voltage values are equal, the transformer T1 and the transformer T2 are equal in value. The secondary side voltages of the transformer T2 cancel each other out, and the output voltage of the resonant converter is zero voltage;

When N>2 and N is an even number, the transformer module includes N transformers. When the relay RY1 is disconnected, if the total voltage of the secondary side from the transformer T1 to the transformer T2/N is the same as the transformer T1+(N/2) to the transformer The total voltage on the secondary side of TN is opposite in polarity and the total voltage value on the secondary side of transformer T1 to transformer T2/N is equal to the total voltage value on the secondary side of transformer T1+(N/2) to transformer TN, so that transformer T1 to transformer The total voltage on the secondary side of T2/N and the total voltage on the secondary side from the transformer T1+(N/2) to the transformer TN cancel each other out, and the resonant converter outputs zero voltage.

According to the above, the advantages of the resonant converter of the present invention over the resonant converter in Fig. 2 are as follows: 1. Change the connection mode of the rectifier circuit on the secondary side of the transformer (without changing the number and specifications of diodes) and reduce the number of relays. 2. The wide-range constant power output function of the topology, and the seamless switching function that is not available in Figure 2 can be realized, and the cost is reduced because the bulky and expensive relay is removed; 2. On the basis of changing the rectifier circuit, increase the A relay, the resonant converter of the present invention can realize the output voltage of 0; 3. It is suitable for the occasions where the output voltage changes more than 2 times and the constant power is seamlessly adjusted in a wide range and the occasions where the output ultra-low voltage is required (for example, near zero voltage) .

Further, the DC power supply includes a single DC power supply or multiple DC power supplies or multiple positive and negative DC power supplies. According to actual needs, the user can choose the same voltage power supply mode, different voltage power supply modes or positive and negative voltage power supply modes to supply power to the switching circuit, Furthermore, the user can apply the resonant converter to more occasions by changing the power supply mode, thereby expanding the application range of the resonant converter.

Further, the external controller includes a microcontroller or a digital processor, the switch tube in the switch circuit includes a field effect transistor (MOSFET) or an insulated gate bipolar transistor (IGBT) or other power electronic switch tubes, and the relay RY1 can be replaced by a bidirectional Switches, diodes in rectifier circuits can be replaced by field effect transistors (MOSFETs) or insulated gate bipolar transistors (IGBTs) or other power electronic switches. When diodes in rectifier circuits are replaced by MOSFETs, since MOSFETs can pass control signals Actively controlling the output voltage of the resonant converter makes the operating mode of the resonant converter more abundant, and can realize a more flexible voltage adjustment mode or achieve a more ideal soft-switching characteristic. In this embodiment, the external controller is a microcontroller, and the switch tube in the switch circuit is a field effect transistor, that is, the switch tube in the switch module is a field effect transistor.

Further, the switch module includes a half-bridge switch module or a full-bridge switch module, and the switch module in this embodiment is a half-bridge switch module. The half-bridge switch module has low cost, simple control, and is more flexible, which is equivalent to reducing the entire resonance. the cost of the converter.

According to the above, the resonant module includes N groups of resonant groups, N≥2 and N is an even number, wherein the resonant group includes a resonant inductor, an excitation inductor and a resonant capacitor; the primary side of the transformer is connected to the switch module via the resonant capacitor and the resonant inductor. One end of the transformer, the non-same-named end of the primary side of the transformer is connected to the other end of the switch module, and an excitation inductance is also provided between the two ends of the primary side of the transformer; or

The homonymic end of the primary side of the transformer is connected to one end of the switch module, the non-homonymous end of the primary side of the transformer is connected to the other end of the switch module through a resonance capacitor and a resonance inductance, and an excitation inductance is arranged between the two ends of the primary side of the transformer. The resonant module is used for reducing the loss caused by the switching on and off of the switching tube in the half-bridge switching module, thereby improving the efficiency of the resonant converter.

According to the above, the half-bridge switch circuit includes N groups of half-bridge switch modules, N≥2 and N is an even number; as shown in Figure 8, the half-bridge switch module includes two switch tubes Q1, Q2; two switch tubes Q1, Q2 It is controlled by the microcontroller; the first end of the switch tube Q1 is connected to the output end of the DC power supply, the second end of the switch tube Q1 is connected to the corresponding resonant group, more specifically, the second end of the switch tube Q1 is connected to the corresponding resonant inductor, The second end of the switch tube Q1 is also connected to the first end of the switch tube Q2; the second end of the switch tube Q2 is connected to the input end of the DC power supply, the second end of the switch tube Q2 is grounded, and the second end of the switch tube Q2 is also connected The primary side of the corresponding transformer is not the same name terminal, and the switching circuit is used to seamlessly switch the series or parallel mode between the two transformers connected at the same terminal of the relay, thereby changing the output voltage of the resonant converter.

In addition, the representation of the half-bridge switch module is not limited to the representation of FIG. 8. As shown in FIG. 9, the half-bridge switch module includes a first switch Q1, a second switch Q2, a third switch Q3, and a fourth switch tube Q4, the first capacitor C1, the second capacitor C2, the first diode D1 and the second diode D2; the turn-on and turn-off of the first switch tube Q1 to the fourth switch tube Q4 are controlled by the microcontroller; The first end of a switch tube Q1 is connected to the output end of the DC power supply, the second end of the first switch tube Q1 is connected to the first end of the second switch tube Q2, and the second end of the second switch tube Q2 is connected to the third switch tube Q3 The first end of the third switch tube Q3 is connected to the first end of the fourth switch tube Q4, the second end of the fourth switch tube Q4 is connected to the input end of the DC power supply, and the second end of the fourth switch tube Q4 Ground; one end of the first capacitor C1 is connected to the first end of the first switch tube Q1, and the other end of the first capacitor C1 is connected to the second end of the fourth switch tube Q4 through the second capacitor C2; The negative electrode is connected to the second end of the first switch tube Q1, the positive electrode of the first diode D1 is connected to the other end of the first capacitor C1, the positive electrode of the first diode D1 is connected to the negative electrode of the second diode D2, and the second diode D1 is connected to the negative electrode of the second diode D2. The positive pole of the pole tube D2 is connected to the second end of the third switch tube Q3; the second end of the second switch tube Q2 is connected to the corresponding resonance group, more specifically, the second end of the second switch tube Q2 is connected to the corresponding resonance inductance, The anode of the first diode D1 is also connected to the non-identical terminal of the primary side of the corresponding transformer.

As shown in Figure 9, the half-bridge switch module is a common three-level half-bridge switch module. Anyone with professional knowledge in the field can understand its working principle through simple derivation. It is assumed that the switches Q1 and Q2 are turned on at the same time. , switch tubes Q3, Q4 are turned on at the same time, switch tubes Q1, Q2 and switch tubes Q3, Q4 are respectively equivalent to a switch tube, so the working mode of the half-bridge switch module is generally the same as that of the ordinary half-bridge switch module (Figure 8 ) is similar, and its advantage is that the voltage stress of the switch tube is relatively low, which is suitable for high-voltage occasions; the following describes the working principles of the full-bridge switch module and the half-bridge switch module are similar, and will not be repeated.

Taking two half-bridges powered by the same voltage as an example, as shown in Figure 10, the DC power supply includes a single DC power supply Vin; the half-bridge switch circuit includes two sets of half-bridge switch modules, of which one set of half-bridge switch modules includes switch tubes Q1, Q2, another set of half-bridge switch modules includes switch tubes Q3 and Q4; the resonance module includes two sets of resonance groups, one of which includes a resonance capacitor C1, a resonance inductance L1 and an excitation inductance, and the other set of resonance groups includes a resonance capacitor C2 , resonant inductance L2 and excitation inductance; the transformer module includes a transformer T1 and a transformer T2; the first rectifier module includes a first diode D1 and a second diode D2, and the second rectifier module includes a third diode D3 and a fourth diode D3 diode D4, the third rectifier module includes a fifth diode D5 and a sixth diode D6; the filter circuit includes a filter capacitor C8;

The turn-on and turn-off of the switch tubes Q1, Q2, Q3, and Q4 are controlled by the microcontroller. The first end of the switch tube Q1 is connected to the output end of the DC power supply Vin, and the second end of the switch tube Q1 is connected to the resonant inductor L1 and the resonant capacitor in turn. C1 is connected to the same name terminal on the primary side of the transformer T1, the second end of the switch tube Q1 is also connected to the first end of the switch tube Q2, the second end of the switch tube Q2 is grounded, and the second end of the switch tube Q2 is also connected to the input of the DC power supply Vin The second end of the switch tube Q2 is also connected to the non-identical end of the primary side of the transformer T1, the first end of the switch tube Q3 is connected to the first end of the switch tube Q1, and the second end of the switch tube Q3 is connected to the resonant inductor L2, The resonance capacitor C2 is connected to the same name terminal of the primary side of the transformer T2, the second end of the switch tube Q3 is connected to the first end of the switch tube Q4, the second end of the switch tube Q4 is connected to the second end of the switch tube Q2, and the second end of the switch tube Q4 is connected. The terminal is connected to the non-identical terminal of the primary side of the transformer T2. There is an excitation inductance (not shown in Figure 10) between the primary side of the transformer T1 and the non-identical terminal of the primary side. The primary side of the transformer T2 has a non-identical name to its primary side. There is an excitation inductance between the ends (not shown in Figure 10);

The secondary side of the transformer T1 is connected to the anode of the first diode D1, the secondary side of the transformer T1 is connected to the anode of the fifth diode D5 through the relay RY1, and the secondary side of the transformer T1 is also connected to the anode of the fifth diode D5. Connect the secondary side homonymous terminal of the transformer T2; the secondary side non-homonymous terminal of the transformer T2 is connected to the anode of the third diode;

Among them, the first diode D1 is connected in series with the second diode D2, the third diode D3 is connected in series with the fourth diode D4, the fifth diode D5 is connected in series with the sixth diode D6, and the first and second diodes are connected in series with the sixth diode D6. The cathodes of the diode D1, the first third diode D3 and the fifth diode D5 are connected to each other, the anodes of the second diode D2, the fourth diode D4 and the sixth diode D6 are connected to each other, and The anode of the second diode D2 is grounded;

One end of the filter capacitor C8 is connected to the negative electrode of the fifth diode D5, and the other end of the filter capacitor C8 is connected to the positive electrode of the sixth diode D6; both ends of the filter capacitor C8 are also connected in parallel with the load RL.

The working principle of the LLC resonant converter: Suppose switch Q1, switch Q2, resonant inductor L1, resonant capacitor C1, and transformer T1 constitute converter A; suppose switch Q3, switch Q4, resonant inductor L2, resonant capacitor C2, and transformer T2 The converter B is constituted, wherein the switch tube Q1 and the switch tube Q2 are complementarily turned on, and the switch tube Q3 and the switch tube Q4 are complementarily turned on. Without considering the dead time, the conduction angle of each switch is 180 degrees. Based on the conduction time of the switch Q1, the conduction angle of the switch Q1 is 0 degrees, and the conduction angle of the switch Q2 is 180 degrees, when the microcontroller controls the switch Q1 and the switch Q3 to conduct synchronously, the conduction angle is 0 degrees; when the microcontroller controls the switch Q2 and the switch Q4 to conduct synchronously, the conduction angle is 180 degrees ; Simple analysis shows that the secondary side voltages of the transformer T1 and the transformer T2 are both positive or negative at the same time. At this time, the output voltages of the transformer T1 and the transformer T2 are connected in series, and the fifth diode D5 and the sixth diode D6 will not Turning on is equivalent to removing it from the circuit. Let the output voltage after rectification and filtering be V1, it can be known that the voltage of V1 is the rated voltage in the ideal state, and the converter A and the converter B are in series mode at this time;

When the microcontroller controls the switch Q1 and the switch Q4 to conduct synchronously, the conduction angle is 0 degrees; when the microcontroller controls the switch Q2 and the switch Q3 to conduct synchronously, the conduction angle is 180 degrees; simple analysis It can be seen that the voltages on the secondary side of the transformer T1 and the transformer T2 have opposite polarities and have the same voltage value. If the relay RY1 is in the off state, it is equivalent to the absence of the fifth diode D5 and the sixth diode D6, and the transformer T1 and the The secondary side voltages of the transformer T2 cancel each other out, and the output voltage after rectification by the first diode D1 to the fourth diode D4 is 0; if the relay RY1 is in the closed state, the secondary side voltages of the transformer T1 and the transformer T2 No longer cancel each other out, but convert to the parallel conduction of the first diode D1 and the third diode D3 (while the sixth diode D6 is conduction) or the second diode D2 and the fourth diode D4 is synchronously turned on in parallel (at the same time, the fifth diode D5 is turned on), which is equivalent to the parallel connection of the output voltages of the transformer T1 and the transformer T2. Let the output voltage after rectification and filtering be V2, it can be seen that the voltage of V2 is ideally equal to the rated voltage. At this time, converter A and converter B are in parallel mode.

As can be seen from the above, the series-parallel mode conversion between converter A and converter B only changes the operating phase of the switch tube in converter B by 180 degrees, and does not change the operating frequency characteristics of the LLC resonant converter, so it does not change the LLC resonance. Gain characteristics of the converter.

In addition, according to the above, at least one diode from the first diode D1 to the sixth diode D6 can be replaced by a field effect transistor (MOSFET) or an insulated gate bipolar transistor (IGBT) or other power electronic switch tubes. , when the first to sixth diodes are replaced with MOSFETs, the function of a bidirectional converter can be realized, and the energy can flow in both directions.

Under the condition that the operating frequencies of converter A and converter B should be consistent, if the operating phase of switch Q3 relative to switch Q1 is between 0 degrees and 180 degrees, it is assumed that the switch Q3 is relative to switch Q1. The working phase is 90 degrees, and the 6 diodes will all work in one cycle according to the working state. At this time, the output voltage of the LLC resonant converter is between V1 and V2. Since the phase shift angle is continuous from 0 degrees to 180 degrees, it can be Therefore, the resonant converter can realize the continuous adjustment of the output voltage from V1 to V2. After theoretical analysis and simulation, it can be known that the operating frequencies of converter A and converter B can be set at converter A and converter B. The resonant frequency (the resonant frequency refers to the LC resonant frequency formed by the resonant inductor L1 and the resonant capacitor C1, wherein the inductance value of the resonant inductor L1 is equal to the inductance value of the resonant inductor L2, and the capacitance value of the resonant capacitor C1 is the same as the resonant capacitor C2. The capacitance value is the same; but the operating frequency is not limited to the resonant frequency, it can be higher or lower than the resonant frequency), at this time, the converter A and the converter B are in phase-shift mode.

The above only assumes that the output voltage of the LLC resonant converter works near the resonant frequency, and then it is deduced that the resonant converter can achieve a continuously adjustable output voltage from the rated voltage to 1/2 times the rated voltage (that is, the range is 1 /2*V _amount to V _amount ).

Considering that the output voltage may be adjusted near the rated voltage, as shown in Figure 1, according to the current basic resonant converter operating range, assuming its input voltage is constant, the current basic resonant converter output voltage range is 0.8*V to 1.2*V, and the LLC resonant converter _{of the} present invention will change the output voltage range to 0.4*V to 1.2*V when _the relay RY1 is closed and turned on, thus expanding _the output by 3 times. voltage range.

It should be specially pointed out that the resonant converter is also called topology. In the actual engineering design, the fifth diode D5 and the sixth diode D6 in the topology ( FIG. 10 ) described in the present invention are actually the same as the first diode D5. Two diodes with the same specifications from diodes D1 to D4 are connected in parallel, because the above analysis shows that the currents flowing through the fifth diode D5 and the sixth diode D6 in the parallel mode are respectively equivalent to the A diode D1 + the third diode D3 and the second diode D2 + the fourth diode D4 flow through the current, so in actual design, the topology output diodes are required to be 8 instead of 6. It can be seen from the comparison with FIG. 2 that the present invention only changes the connection mode of the eight diodes in FIG. 2 , but does not change the specifications of the diodes, but reduces the number of relays, thereby reducing the cost of the topology and improving the performance of the topology.

The following is an analysis of its working mode through specific numerical values (taking the LLC resonant converter as an example): when the relay RY1 is closed and turned on, the output voltage adjustment process of the LLC resonant converter is as follows (assuming that the output voltage adjustment range of the resonant converter requires 20V- 60V): If the output voltage 50V is set as the resonance point of the series mode, the resonance point is the rated voltage point. From the above analysis, it can be known that V1=50V, then V2=50V/2=25V. When the set value of the output voltage is between 50V-60V, the converter A and the converter B work in series mode, and the output voltage is adjusted by adjusting the operating frequencies of the converter A and the converter B. According to the LLC resonance conversion Gain characteristics of the converter, when the operating frequencies of converter A and converter B are lower than the resonant frequency (at the resonant frequency, the output voltage of the LLC resonant converter is defined as the rated voltage, and the gain corresponding to the output voltage is 1), when, Then the output voltage of the resonant converter is higher than the rated voltage, and the gain corresponding to the output voltage is 1.2, which is the same as the gain of the current basic resonant converter; when the output voltage is set between 40V-50V, the conversion Converter A and converter B work in series mode, the operating frequency of converter A and converter B is higher than the resonant frequency, and the minimum gain corresponding to 40V voltage is 0.8; when the output voltage setting value is between 25V-30V, then Converter A and converter B work in parallel mode, and the operating frequency of converter A and converter B is lower than the resonant frequency, where 25V is the aforementioned V2 voltage, and 30V is half of 60V; similarly, when the output voltage setting value When the voltage is between 20V-25V, the converter A and the converter B work in parallel mode, and the operating frequency of the converter A and the converter B is higher than the resonant frequency; when the output voltage setting value is between 30V-40V, The converters A and B work in the phase-shift mode, and the operating frequencies of the converters A and B are equal to the resonant frequency (the frequency is not limited to be the resonant frequency in practical applications).

It can be seen from the above specific analysis that when the rated voltage is 50V, the output voltage range of the current basic resonant converter is only 40V-60V (that is, the gain adjustment capability of 0.8-1.2 times), while the output voltage of the resonant converter of the present invention is only 40V-60V. It can realize the seamless adjustment of 20V-60V, which greatly widens its output voltage; and when the output voltage range is 20V-60V, the output power is kept unchanged, so the resonant converter of the present invention is suitable for a wide range, continuous In the case of constant power adjustment.

When the microcontroller controls the relay RY1 to be disconnected, it can be seen through simple analysis that if the microcontroller still controls the two transformers to work in parallel mode (that is, the phases of the two transformers are 180 degrees), the output voltage of the LLC resonant converter is 0V. If the microcontroller controls the two transformers to work in series mode, the output voltage of the LLC resonant converter can reach 60V. In this case, the working mode of the present invention is similar to the topology shown in FIG. 11 .

As shown in FIG. 11 , the topology in FIG. 11 does not have the fifth diode D5, the sixth diode D6 and the relay RY1. It is assumed that the number of diodes connected to the secondary side of the transformer in the present invention and the topology shown in FIG. 11 are both 8 , the significant difference between the present invention and the topology shown in Figure 11 is: 1. The topology shown in Figure 11 is actually that the transformer has been working in series mode all the time. When the output voltage is low and the output current is large (constant power characteristic requirements), the original transformer The diameter of the side and secondary windings is large; 2. The two transformers shown in Figure 11 always work in the phase-shift mode when outputting the rated voltage, especially the phase-shift angle near 1/2 times the rated voltage is large, which will cause the transformer to The two field effect transistors of the leading bridge arm on the primary side cannot achieve zero-voltage turn-on, and the turn-off current of the two field effect transistors of the lagging bridge arm increases many times, which has reliability risks and high cost; 3. Based on the above reasons, Fig. The topology theory shown in 11 has many researches, but almost no products appear in engineering practice, so it is not practical.

The common points of the present invention and the topology shown in Figure 11 are: 1. Under the condition of the same output voltage and output current, the total number and specifications of the output diodes are the same (generally 8); 2. The output voltage can be achieved at Seamless adjustment from zero voltage to rated voltage; 3. Constant power output cannot be achieved under 1/2 times the rated voltage (in fact, when the output voltage is very low, such as near zero voltage, it is not necessary to require constant power output. Practical); 4. The control method is similar when the phase is shifted.

In addition, taking four half-bridges powered by different voltages as an example, as shown in Figure 12, the DC power supply includes DC power supplies Vin1, Vin2, Vin3, and Vin4; the half-bridge switching circuit includes four sets of half-bridge switch modules, the first set of half-bridge The switch module includes switch tubes Q1 and Q2, the second group of switch modules includes switch tubes Q3 and Q4; the third group of half-bridge switch modules includes switch tubes Q5 and Q6, the fourth group of switch modules includes switch tubes Q7 and Q8; the resonance module includes The first resonance group, the second resonance group, the third resonance group and the fourth resonance group, the first resonance group includes the resonance inductance L1, the resonance capacitance C1 and the excitation inductance, and the second resonance group includes the resonance inductance L2, the resonance capacitance C2 and Excitation inductance, the third resonance group includes resonance inductance L3, resonance capacitor C3 and excitation inductance, and the third resonance group includes resonance inductance L4, resonance capacitor C4 and excitation inductance; the transformer module includes transformer T1, transformer T2, transformer T3 and transformer T4; The first rectifier module includes a first diode D1 and a second diode D2, the second rectifier module includes a third diode D3 and a fourth diode D4, and the third rectifier module includes a fifth diode D5 and a fourth diode D4. the sixth diode D6; the filter circuit includes a filter capacitor C8;

The turn-on and turn-off of the switch tubes Q1 to Q8 are controlled by the microcontroller. The first end of the switch tube Q1 is connected to the output end of the DC power supply Vin1, and the second end of the switch tube Q1 is connected to the transformer T1 through the resonant inductor L1 and the resonant capacitor C1 in turn. The second end of the switch tube Q1 is also connected to the first end of the switch tube Q2, the second end of the switch tube Q2 is connected to the non-same name end of the primary side of the transformer T1, the second end of the switch tube Q2 is grounded to GND1, the switch The second end of the tube Q2 is also connected to the input end of the DC power supply Vin1;

The first end of the switch tube Q3 is connected to the output end of the DC power supply Vin2, the second end of the switch tube Q3 is connected to the same name terminal on the primary side of the transformer T2 through the resonant inductor L2 and the resonant capacitor C2 in turn, and the second end of the switch tube Q3 is also connected to the switch. The first end of the tube Q4, the second end of the switch tube Q4 is connected to the non-identical end of the primary side of the transformer T2, the second end of the switch tube Q4 is grounded to GND2, and the second end of the switch tube Q4 is also connected to the input end of the DC power supply Vin2;

The first end of the switch tube Q5 is connected to the output end of the DC power supply Vin3, the second end of the switch tube Q5 is connected to the same name terminal on the primary side of the transformer T3 through the resonant inductor L3 and the resonant capacitor C3 in turn, and the second end of the switch tube Q5 is also connected to the switch. The first end of the tube Q6, the second end of the switch tube Q6 is connected to the non-identical end of the primary side of the transformer T3, the second end of the switch tube Q6 is grounded to GND3, and the second end of the switch tube Q6 is also connected to the input end of the DC power supply Vin3;

The first end of the switch tube Q7 is connected to the output end of the DC power supply Vin4, the second end of the switch tube Q7 is connected to the same name terminal of the primary side of the transformer T4 through the resonant inductor L4 and the resonant capacitor C4 in turn, and the second end of the switch tube Q7 is also connected to the switch. The first end of the tube Q8, the second end of the switch tube Q8 is connected to the non-identical end of the primary side of the transformer T4, the second end of the switch tube Q8 is grounded to GND4, and the second end of the switch tube Q8 is also connected to the input end of the DC power supply Vin4;

There are corresponding excitation inductances (not shown in Figure 12) between the primary side homonymous end of the transformers T1, T2, T3, and T4 and their primary side non-homonymous end respectively, and the secondary side homonymous end of the transformer T1 is connected to the first diode. The positive pole of D1, the non-same-named terminal of the secondary side of the transformer T1 is connected to the same-named terminal of the secondary side of the transformer T2, and the non-identical terminal of the secondary side of the transformer T2 is connected to the positive pole of the fifth diode D5 through the relay RY1, and the secondary side of the transformer T2 is connected. The non-homonymous terminal on the side is connected to the secondary-side homonymic terminal of the transformer T3, the secondary-side non-homonymous terminal of the transformer T3 is connected to the secondary-side homonymic terminal of the transformer T4, and the secondary-side non-homonymous terminal of the transformer T4 is connected to the anode of the third diode. ;

Among them, the first diode D1 is connected in series with the second diode D2, the third diode D3 is connected in series with the fourth diode D4, the fifth diode D5 is connected in series with the sixth diode D6, and the first and second diodes are connected in series with the sixth diode D6. The cathodes of the diode D1, the first third diode D3 and the fifth diode D5 are connected to each other, the anodes of the second diode D2, the fourth diode D4 and the sixth diode D6 are connected to each other, and The anode of the second diode D2 is grounded;

One end of the filter capacitor C8 is connected to the negative electrode of the fifth diode D5, and the other end of the filter capacitor C8 is connected to the positive electrode of the sixth diode D6; both ends of the filter capacitor C8 are also connected in parallel with the load RL.

The above-mentioned DC power sources Vin1, Vin2, Vin3, and Vin4 can provide the same voltage, different voltages, or different positive and negative voltages to the half-bridge switch module. The resonant converter has the same working principle as the previous LLC resonant converter, and will not be repeated here.

Embodiment 2

The difference between this embodiment and the first embodiment is that the switch module includes a full-bridge switch module. Compared with the half-bridge switch module, the full-bridge switch module is suitable for higher power occasions.

Among them, there are many ways to choose the full-bridge switch module. As shown in FIG. 13, the full-bridge switch module includes a first switch tube Q1, a second switch tube Q2, a third switch tube Q3 and a fourth switch tube Q4; The conduction and closing of the switch tube Q1 to the fourth switch tube Q4 are controlled by the microcontroller; the first end of the first switch tube Q1 is connected to the output end of the DC power supply, and the second end of the first switch tube Q1 is connected to the second switch tube The first end of Q2, the second end of the second switch Q2 is connected to the input end of the DC power supply, the second end of the second switch Q2 is grounded; the first end of the third switch Q3 is connected to the first end of the first switch Q1 One end, the second end of the third switch tube Q3 is connected to the first end of the fourth switch tube Q4, the second end of the fourth switch tube Q4 is connected to the second end of the second switch tube Q2; the first end of the first switch tube Q1 The two ends are connected to the corresponding resonant group. More specifically, the second end of the first switch Q1 is connected to the corresponding resonant inductor, and the second end of the third switch Q3 corresponds to the primary side non-identical end of the transformer. The full-bridge switch module is a full-bridge switch module with the simplest connection method, and has low cost and wide application.

As shown in FIG. 14, the full-bridge switch module includes a first switch transistor Q1, a second switch transistor Q2, a third switch transistor Q3, a fourth switch transistor Q4, a fifth switch transistor Q5, a sixth switch transistor Q6, and a first capacitor C1, the second capacitor C2, the first diode D1 and the second diode D2; the turn-on and turn-off of the first switch tube Q1 to the sixth switch tube Q6 are controlled by the microcontroller, wherein the first switch tube Q1 The first end is connected to the output end of the DC power supply, the second end of the first switch tube Q1 is connected to the first end of the second switch tube Q2, the second end of the second switch tube Q2 is connected to the first end of the third switch tube Q3, The second end of the third switch tube Q3 is connected to the first end of the fourth switch tube Q4, the second end of the fourth switch tube Q4 is connected to the input end of the DC power supply, and the second end of the fourth switch tube Q4 is grounded; the fifth switch The first end of the tube Q5 is connected to the first end of the first switch tube Q1, the second end of the fifth switch tube Q5 is connected to the first end of the sixth switch tube Q6, and the second end of the sixth switch tube Q6 is connected to the fourth switch The second end of the tube Q4; one end of the first capacitor C1 is connected to the first end of the first switch tube Q1, and the other end of the first capacitor C1 is connected to the second end of the fourth switch tube Q4 through the second capacitor C2; The cathode of the pole tube D1 is connected to the second end of the first switch tube Q1, the anode of the first diode D1 is connected to the other end of the first capacitor C1; the anode of the first diode D1 is also connected to the second end of the second diode D2 The cathode, the anode of the second diode D2 is connected to the second end of the third switch tube Q3; the second end of the fifth switch tube Q5 is connected to the corresponding resonance group, more specifically, the second end of the fifth switch tube Q5 The corresponding resonant inductor is connected, and the second end of the second switch tube Q2 is connected to the non-identical end of the primary side of the transformer. Compared with the full-bridge switch modules of other connection modes, the full-bridge switch module has many advantages and more flexible control modes.

As shown in FIG. 15 , the full-bridge switch module includes a first switch Q1, a second switch Q2, a third switch Q3, a fourth switch Q4, a fifth switch Q5, a sixth switch Q6, and a seventh switch tube Q7, eighth switch tube Q8, first capacitor C1, second capacitor C2, third capacitor C3, fourth capacitor C4, first diode D1, second diode D2, third diode D3 and The fourth diode D4; the conduction or closing of the first switch tube Q1 to the eighth switch tube Q8 is controlled by the microcontroller; wherein, the first end of the first switch tube Q1 is connected to the output end of the DC power supply, and the first switch tube The second end of the tube Q1 is connected to the first end of the second switch tube Q2, the second end of the second switch tube Q2 is connected to the first end of the third switch tube Q3, and the second end of the third switch tube Q3 is connected to the fourth switch The first end of the tube Q4, the second end of the fourth switch tube Q4 is connected to the input end of the DC power supply, the second end of the fourth switch tube Q4 is grounded; one end of the first capacitor C1 is connected to the first end of the first switch tube Q1 , the other end of the first capacitor C1 is connected to the second end of the fourth switch tube Q4 through the second capacitor C2; the cathode of the first diode D1 is connected to the second end of the first switch tube Q1, and the The anode is connected to the other end of the first capacitor C1, the anode of the first diode D1 is also connected to the cathode of the second diode D2, the anode of the second diode D2 is connected to the second end of the third switch tube Q3, the second The second end of the switch tube Q2 is connected to the non-identical end of the primary side of the corresponding transformer;

The first end of the fifth switch tube Q5 is connected to the first end of the first switch tube Q1, the second end of the fifth switch tube Q5 is connected to the first end of the sixth switch tube Q6, and the second end of the sixth switch tube Q6 is connected to The first end of the seventh switch tube Q7, the second end of the seventh switch tube Q7 is connected to the first end of the eighth switch tube Q8, and the second end of the eighth switch tube Q8 is connected to the second end of the fourth switch tube Q4; One end of the third capacitor C3 is connected to the first end of the fifth switch tube Q5, the other end of the third capacitor C3 is connected to the second end of the eighth switch tube Q8 via the fourth capacitor C4; the negative electrode of the third diode D3 is connected to the second end of the eighth switch tube Q8. The second end of the five switch tube Q5, the anode of the third diode D3 is connected to the other end of the third capacitor C3, the anode of the third diode D3 is connected to the cathode of the fourth diode D4, and the fourth diode D4 The positive pole of the first switch Q7 is connected to the second end of the seventh switch tube Q7, the second end of the sixth switch tube Q6 is connected to the corresponding resonance group, and the second end of the sixth switch tube Q6 is connected to the corresponding resonance inductor. Compared with full-bridge switch modules of other connection methods, the full-bridge switch module has the advantages of being applicable to occasions with higher voltage and higher power.

The connection modes of the above-mentioned full-bridge switch modules are not limited to the connection modes shown in FIGS. 13 , 14 and 15 , and will not be repeated here.

Taking two full bridges powered by different voltages as an example, as shown in Figure 16, the DC power supply includes DC power supplies Vin1 and Vin2, and the full-bridge switch circuit includes two groups of full-bridge switch modules, one of which is a full-bridge switch module including a first switch tube. Q11, second switch Q12, third switch Q13, fourth switch Q14, another full-bridge switch module includes a first switch Q21, a second switch Q22, a third switch Q23, and a fourth switch Q24 ,

The resonance module includes two groups of resonance groups, one of which includes a resonance capacitor C1, a resonance inductance L1 and an excitation inductance, the other group of resonance groups includes a resonance capacitor C2, a resonance inductance L2 and an excitation inductance, and the transformer module includes a transformer T1 and a transformer T2 ; The first rectifier module includes a first diode D1 and a second diode D2, the second rectifier module includes a third diode D3 and a fourth diode D4, and the third rectifier module includes a fifth diode D5 and the sixth diode D6; the filter circuit includes a filter capacitor C8;

The output end of the DC power supply Vin1 is connected to the first end of the first switch tube Q11, the second end of the first switch tube Q11 is sequentially connected to the resonant inductor L1, and the resonant capacitor C1 is connected to the primary side of the transformer T1 with the same name. The second end is also connected to the first end of the second switch tube Q12, the second end of the second switch tube Q12 is grounded to GND1, the second end of the second switch tube Q12 is connected to the input end of the DC power supply Vin1, and the third switch tube Q13 The first end is connected to the first end of the first switch tube Q11, the second end of the third switch tube Q13 is connected to the non-identical end of the primary side of the transformer T1, and the second end of the fourth switch tube Q14 is connected to the second end of the second switch tube Q12. two ends;

The output end of the DC power supply Vin2 is connected to the first end of the first switch tube Q21, the second end of the first switch tube Q21 is sequentially connected to the resonant inductor L2, and the resonant capacitor C2 is connected to the primary side of the transformer T2 with the same name. The second end is also connected to the first end of the second switch tube Q22, the second end of the second switch tube Q22 is grounded to GND2, the second end of the second switch tube Q22 is connected to the input end of Vin2 of the DC power supply, and the third switch tube Q23 The first end of the third switch tube Q23 is connected to the first end of the first switch tube Q21, the second end of the third switch tube Q23 is connected to the non-identical end of the primary side of the transformer T1, and the second end of the third switch tube Q23 is connected to the fourth switch tube Q24. the first end, the second end of the fourth switch tube Q24 is connected to the second end of the second switch tube Q22;

There is a corresponding excitation inductance (not shown in Figure 16) between the primary side homonymous end and the secondary side non-homonymous end of the transformers T1 and T2, and the secondary side homonymous end of the transformer T1 is connected to the positive pole of the first diode D1, The non-homonymous end of the secondary side of the transformer T1 is connected to the positive electrode of the fifth diode D5, and the non-homonymous end of the secondary side of the transformer T1 is also connected to the secondary-side homonymic end of the transformer T2; The anode of the three diodes D3;

Among them, the first diode D1 is connected in series with the second diode D2, the third diode D3 is connected in series with the fourth diode D4, the fifth diode D5 is connected in series with the sixth diode D6, and the first and second diodes are connected in series with the sixth diode D6. The cathodes of the diode D1, the first third diode D3 and the fifth diode D5 are connected to each other, the anodes of the second diode D2, the fourth diode D4 and the sixth diode D6 are connected to each other, and The anode of the second diode D2 is grounded;

One end of the filter capacitor C8 is connected to the negative electrode of the fifth diode D5, and the other end of the filter capacitor C8 is connected to the positive electrode of the sixth diode D6; both ends of the filter capacitor C8 are also connected in parallel with the load RL.

The above-mentioned DC power sources Vin1 and Vin2 can provide the same voltage, different voltages, or different positive and negative voltages to the full-bridge switch module. The working principle of the resonant converter is similar to that of the LLC resonant converter in the first embodiment, and will not be repeated here. .

The above-mentioned embodiments are only preferred embodiments of the present invention, and cannot be used to limit the scope of protection of the present invention. Any insubstantial changes and substitutions made by those skilled in the art on the basis of the present invention belong to the scope of the present invention. Scope of protection claimed.

Claims (13)

1. A resonant converter of series-parallel seamless conversion, comprising a DC power supply, a switch circuit, a resonant circuit, a rectifier circuit and a filter circuit that are electrically connected in turn; the switch circuit is controlled by an external controller; it is characterized in that, the The resonance circuit includes a resonance module and a transformer module, the transformer module includes N transformers, the resonance module includes N groups of resonance groups, the switch circuit includes N groups of switch modules, N≥2 and N is an even number; the rectifier circuit It includes a first rectifier module, a second rectifier module and a third rectifier module; wherein, The primary side homonymic end of the transformer is connected to one end corresponding to the switch module through the corresponding resonance group, and the primary side non-homonymous end of the transformer is connected to the other end corresponding to the switch module; If N=2, the same-named terminal on the secondary side of the first transformer is connected to the midpoint of the bridge arm of the first rectifier module, and the non-identical terminal on the secondary side of the first transformer is connected to the second terminal. The secondary side of the transformer is connected to the same name terminal, the secondary side non-homonymous terminal of the second transformer is connected to the midpoint of the bridge arm of the second rectifier module, and the secondary side non-homonymous terminal of the first transformer is connected. connected to the midpoint of the bridge arm of the third rectifier module; or If N>2 and N is an even number, the same-named terminal on the secondary side of the first transformer is connected to the midpoint of the bridge arm of the first rectifier module, and the non-identical terminal on the secondary side of the first transformer is connected to the midpoint of the bridge arm of the first rectifier module. The secondary side of the second transformer is connected to the same name terminal, the secondary side non-homonymous terminal of the adjacent transformer is connected to the secondary side homonymic terminal, and the secondary side non-homonymous terminal of the Nth transformer is connected to the secondary side. The midpoint of the bridge arm of the second rectifier module, the N/2 th non-same-named end of the secondary side of the transformer is connected to the midpoint of the bridge arm of the third rectifier module. 2 . The resonant converter according to claim 1 , wherein, if N=2, between the non-same-named end of the secondary side of the first transformer and the midpoint of the bridge arm of the third rectifier module. 3 . is provided with a relay; or If N>2 and N is an even number, a relay is provided between the non-identical terminal on the secondary side of the N/2th transformer and the midpoint of the bridge arm of the third rectifier module. 3. The resonant converter according to claim 1 or 2, wherein the DC power supply comprises a single DC power supply or multiple DC power supplies or multiple positive and negative DC power supplies. 4. The resonant converter according to claim 1, wherein the switch module comprises a half-bridge switch module or a full-bridge switch module. 5. The resonant converter according to claim 3, wherein the switch module comprises a half-bridge switch module or a full-bridge switch module. 6 . The resonant converter according to claim 4 , wherein the half-bridge switch module comprises two switch tubes; one of the first ends of the switch tubes is connected to the output end of the DC power supply, and the other The second end of the switch tube is connected to the corresponding resonance group, the second end of one of the switch tubes is also connected to the first end of the other switch tube; the second end of the other switch tube is connected to the other. The input end of the DC power supply, the second end of the other switch tube is grounded, and the second end of the other switch tube is also connected to the non-identical end of the primary side corresponding to the transformer. 7. The resonant converter according to claim 4, wherein the half-bridge switch module comprises a first switch, a second switch, a third switch, a fourth switch, a first capacitor, a second switch a capacitor, a first diode and a second diode; the first end of the first switch tube is connected to the output end of the DC power supply, and the second end of the first switch tube is connected to the second switch tube The first end of the second switch tube is connected to the first end of the third switch tube, and the second end of the third switch tube is connected to the first end of the fourth switch tube, so The second end of the fourth switch tube is connected to the input end of the DC power supply, and the second end of the fourth switch tube is grounded; one end of the first capacitor is connected to the first end of the first switch tube, so The other end of the first capacitor is connected to the second end of the fourth switch tube through the second capacitor; the cathode of the first diode is connected to the second end of the first switch tube, and the first The anode of the diode is connected to the other end of the first capacitor, the anode of the first diode is connected to the cathode of the second diode, and the anode of the second diode is connected to the third switch The second end of the second switch tube is connected to the corresponding resonance group, and the anode of the first diode is also connected to the non-identical end of the primary side corresponding to the transformer. 8 . The resonant converter according to claim 4 , wherein the full-bridge switch module comprises a first switch transistor, a second switch transistor, a third switch transistor and a fourth switch transistor; the first switch transistor The first end of the first switch is connected to the output end of the DC power supply, the second end of the first switch tube is connected to the first end of the second switch tube, and the second end of the second switch tube is connected to the DC power supply The input end of the second switch tube is grounded; the first end of the third switch tube is connected to the first end of the first switch tube, and the second end of the third switch tube is connected to the The first end of the fourth switch tube, the second end of the fourth switch tube is connected to the second end of the second switch tube; the second end of the first switch tube is connected to the corresponding resonance group, so The second end of the third switch tube is connected to the non-identical end corresponding to the primary side of the transformer. 9 . The resonant converter according to claim 4 , wherein the full-bridge switch module comprises a first switch, a second switch, a third switch, a fourth switch, a fifth switch, a third switch six switch tubes, a first capacitor, a second capacitor, a first diode and a second diode; the first end of the first switch tube is connected to the output end of the DC power supply, and the first switch tube The second end is connected to the first end of the second switch tube, the second end of the second switch tube is connected to the first end of the third switch tube, and the second end of the third switch tube is connected to the The first end of the fourth switch tube, the second end of the fourth switch tube is connected to the input end of the DC power supply, the second end of the fourth switch tube is grounded; the first end of the fifth switch tube Connect the first end of the first switch tube, the second end of the fifth switch tube is connected to the first end of the sixth switch tube, and the second end of the sixth switch tube is connected to the fourth switch the second end of the first capacitor; one end of the first capacitor is connected to the first end of the first switch tube, and the other end of the first capacitor is connected to the second end of the fourth switch tube through the second capacitor ; The cathode of the first diode is connected to the second end of the first switch tube, the anode of the first diode is connected to the other end of the first capacitor, and the anode of the first diode is also connected to the cathode of the second diode, the anode of the second diode is connected to the second end of the third switch tube; the second end of the fifth switch tube is connected to the corresponding resonance group, The second end of the second switch tube is connected to the non-identical end corresponding to the primary side of the transformer. 10. The resonant converter according to claim 4, wherein the full-bridge switch module comprises a first switch, a second switch, a third switch, a fourth switch, a fifth switch, a Six switch tubes, seventh switch tube, eighth switch tube, first capacitor, second capacitor, third capacitor, fourth capacitor, first diode, second diode, third diode and fourth diode; the first end of the first switch tube is connected to the output end of the DC power supply, the second end of the first switch tube is connected to the first end of the second switch tube, and the second switch tube The second end of the tube is connected to the first end of the third switch tube, the second end of the third switch tube is connected to the first end of the fourth switch tube, and the second end of the fourth switch tube is connected to The input end of the DC power supply, the second end of the fourth switch tube is grounded; one end of the first capacitor is connected to the first end of the first switch tube, and the other end of the first capacitor is connected to the The second capacitor is connected to the second end of the fourth switch tube; the cathode of the first diode is connected to the second end of the first switch tube, and the anode of the first diode is connected to the first The other end of the capacitor, the anode of the first diode is also connected to the cathode of the second diode, the anode of the second diode is connected to the second end of the third switch tube, the The second end of the two switching tubes is connected to the non-identical end of the primary side corresponding to the transformer; The first end of the fifth switch tube is connected to the first end of the first switch tube, the second end of the fifth switch tube is connected to the first end of the sixth switch tube, and the sixth switch tube The second end of the seventh switch tube is connected to the first end of the seventh switch tube, the second end of the seventh switch tube is connected to the first end of the eighth switch tube, and the second end of the eighth switch tube is connected to the the second end of the fourth switch tube; one end of the third capacitor is connected to the first end of the fifth switch tube, and the other end of the third capacitor is connected to the eighth switch tube through the fourth capacitor the second end of the third diode; the cathode of the third diode is connected to the second end of the fifth switch tube, the anode of the third diode is connected to the other end of the third capacitor, the third and second The anode of the pole tube is connected to the cathode of the fourth diode, the anode of the fourth diode is connected to the second end of the seventh switch tube, and the second end of the sixth switch tube is connected to the corresponding resonance group. 11. The resonant converter according to claim 6, wherein the first rectifier module comprises a first diode and a second diode; the second rectifier module comprises a third diode and a second diode Four diodes; the third rectifier module includes a fifth diode and a sixth diode; the first diode is connected in series with the second diode, and the third diode is connected with the The fourth diode is connected in series, the fifth diode is connected in series with the sixth diode, and the cathodes of the first diode, the third diode and the fifth diode are connected in series. connected to each other, the anodes of the second diode, the fourth diode and the sixth diode are connected to each other, and the anodes of the second diodes are grounded; The positive pole is connected to the same name terminal on the secondary side of the first transformer, the positive pole of the third diode is connected to the non-identical terminal on the secondary side of the N/2th transformer, and the positive pole of the fifth diode is connected Connect the secondary side non-homonymous terminal of the Nth said transformer. 12 . The resonant converter according to claim 11 , wherein the switch tube comprises a field effect transistor or an insulated gate bipolar transistor, and at least one of the first diode to the sixth diode is 12 . Diodes are replaced by field effect transistors or insulated gate bipolar transistors. 13. The resonant converter of claim 2, wherein the relay is replaced by a bidirectional switch.