CN111786583A - High Frequency Resonant Inverter - Google Patents

Abstract

The invention provides a high-frequency resonance inverter. The inverter comprises an inverter circuit and a resonant circuit; the inverter circuit is respectively connected with the resonant circuit and an external direct-current power supply, is also connected with a first plurality of control ends, is suitable for converting direct-current power supply voltage into symmetrical square-wave voltage under the control of control signals accessed by the first plurality of control ends, and outputs the symmetrical square-wave voltage to the resonant circuit; the resonant circuit is connected with an external load and is also connected with a plurality of second control ends, the voltage gain of the resonant circuit can be regulated and controlled under the control of control signals accessed by the plurality of second control ends, and the resonant circuit converts the symmetrical square wave voltage into expected alternating voltage and outputs the expected alternating voltage to the load. The inverter provided by the invention can dynamically adjust the voltage gain.

Description

High Frequency Resonant Inverter

technical field

The invention relates to the technical field of inverters, in particular to a high-frequency resonance inverter.

Background technique

SPWM (Pulse Width Modulation) inverter is based on the principle of area equivalence, that is, when narrow pulses with the same impulse and different shapes are added to the link with inertia, the effect is basically the same, and the pulse width changes according to the sine law The PWM waveform equivalent to the sine wave, that is, the SPWM waveform, controls the on-off of the switch tube in the inverter circuit, so that the area of the output pulse voltage is equal to the area of the desired output sine wave in the corresponding interval. By changing the modulation wave The frequency and amplitude of the inverter can adjust the frequency and amplitude of the output voltage of the inverter circuit.

Considering that a continuous function can be approximated or replaced by an infinite number of discrete functions, then a sine wave can be replaced by a plurality of rectangular pulse waves of different amplitudes; a sine half wave is divided into a plurality of equal width and unequal amplitude. If the area of each rectangular wave is equal to the area of the sine wave in the corresponding time period, the combined area of this series of rectangular waves is equal to the area of the sine wave, that is, it has an equivalent effect.

The traditional SPWM type (pulse width modulation) inverter is controlled based on the area equivalent principle, and the output state is limited by the switching frequency of the switch tube, so it is difficult to achieve high-frequency voltage output. Moreover, due to the limitations of current power electronic devices such as voltage stress, it is difficult to achieve adjustable output voltage gain, which severely restricts its application in high-frequency converters.

SUMMARY OF THE INVENTION

In view of the above-mentioned defects in the prior art, the present invention provides a high-frequency resonant inverter, which is used to solve some technical problems existing in the related art.

In a first aspect, an embodiment of the present invention provides a high-frequency resonant inverter, including an inverter circuit and a resonant circuit;

The inverter circuit is respectively connected with the resonant circuit and the external DC power supply, and is also connected with the first several control terminals, and is suitable for converting the DC power supply voltage under the control of the control signals connected to the first several control terminals. forming a symmetrical square wave voltage, and outputting the symmetrical square wave voltage to the resonant circuit;

The resonant circuit is connected to an external load, and is also connected to the second plurality of control terminals, and is suitable for controlling the voltage gain of the resonant circuit under the control of the control signals connected to the second plurality of control terminals, and the resonance circuit can be adjusted. The circuit converts the symmetrical square wave voltage into an expected AC voltage and outputs it to the load.

Optionally, the resonant circuit includes a controllable capacitor unit; the controllable capacitor unit includes at least a bidirectional controllable switch circuit and a controllable capacitor; wherein the first end of the bidirectional controllable switch circuit is connected to a controllable capacitor. The first end of the control capacitor is connected to the first end of the controllable capacitor unit; the second end of the bidirectional controllable switch circuit is connected to the second end of the controllable capacitor, and serves as the controllable capacitor unit at the same time the second end of ;

The bidirectional controllable switch circuit is also connected to the second plurality of control terminals, and under the control of the control signals connected to the second plurality of control terminals, the controllable capacitor unit provides four working modes, so that all The equivalent capacitance value of the controllable capacitor in one switching cycle can be adjusted:

In the first working mode, current flows from the first end of the controllable capacitor unit to the second end of the controllable capacitor unit through the bidirectional controllable switch circuit, and the controllable capacitor does not work; the second works In the mode, current flows from the first end of the controllable capacitor unit to the second end of the controllable capacitor unit through the controllable capacitor, and the bidirectional controllable switch circuit is turned off;

In the third working mode, current flows from the second end of the controllable capacitor unit to the first end of the controllable capacitor unit through the bidirectional controllable switch circuit, and the controllable capacitor does not work;

In the fourth working mode, current flows from the second end of the controllable capacitor unit to the first end of the controllable capacitor unit through the controllable capacitor, and the bidirectional controllable switch circuit is turned off.

Optionally, the bidirectionally controllable switch circuit includes two switch tubes connected in series; both of the two switch tubes are connected in parallel with a diode in anti-parallel; the two switch tubes are arranged on top of each other.

Optionally, the resonant circuit further includes a first inductor and a first capacitor; wherein,

The first end of the first inductor is connected to the first end of the inverter circuit, and the second end of the first inductor is connected to the first end of the controllable capacitance unit;

The second end of the controllable capacitor unit is connected to the first end of the first capacitor, and the second end of the first capacitor is connected to the third end of the inverter circuit;

Two ends of the first capacitor are respectively connected to two ends of the load as two output ends of the inverter.

Optionally, the resonant circuit further includes a first inductor, a second inductor and a first capacitor; wherein,

The first end of the first inductor is connected to the first end of the inverter circuit, and the second end of the first inductor is connected to the first end of the controllable capacitance unit;

The second end of the controllable capacitor unit is respectively connected to the first end of the second inductor and the first end of the first capacitor;

The second end of the second inductor and the second end of the first capacitor are respectively connected to the third end of the inverter circuit;

Two ends of the first capacitor are respectively connected to two ends of the load as two output ends of the inverter.

Optionally, the resonant circuit further includes a first inductor, a second inductor and a first capacitor; wherein,

The first end of the first inductor is connected to the first end of the inverter circuit, and the second end of the first inductor is connected to the first end of the controllable capacitance unit;

the second end of the controllable capacitor unit is connected to the first end of the first capacitor;

the second end of the first capacitor is connected to the first end of the second inductor;

The second end of the second inductor is connected to the third end of the inverter circuit;

The first end of the first capacitor and the second end of the second inductor are respectively connected to both ends of the load as two output ends of the inverter.

Optionally, the resonant circuit further includes a first inductor, a second inductor and a first capacitor; wherein,

The first end of the first inductor is connected to the first end of the inverter circuit, and the second end of the first inductor is connected to the first end of the first capacitor;

the second end of the first capacitor is connected to the first end of the controllable capacitor unit;

the second end of the controllable capacitance unit is connected to the first end of the second inductor;

The second end of the second inductor is connected to the third end of the inverter circuit;

The first end of the controllable capacitance unit and the second end of the second inductance are respectively connected to both ends of the load as two output ends of the inverter.

Optionally, the resonant circuit includes a controllable inductance unit; the controllable inductance unit at least includes a bidirectional controllable switch circuit and a controllable inductance connected in series; wherein,

The first end of the bidirectional controllable switch circuit is connected to the second end of the controllable inductance, the first end of the controllable inductance serves as the first end of the controllable inductance unit, and the bidirectional controllable switch The second end of the circuit is used as the second end of the controllable inductance unit;

The bidirectional controllable switch circuit is also connected to the second plurality of control terminals, and under the control of the control signals connected to the second plurality of control terminals, the controllable inductance unit provides three working modes, so that all the The equivalent inductance value of the controllable inductance in one switching cycle can be adjusted:

In the first working mode, current flows from the first end of the controllable inductance unit to the second end of the controllable inductance unit through the controllable inductance and the bidirectional controllable switch circuit in sequence;

In the second working mode, the bidirectional controllable switch circuit is turned off, and no current flows through the controllable inductance unit;

In the third working mode, current flows from the second end of the controllable inductance unit to the first end of the controllable inductance unit through the bidirectional controllable switch circuit and the controllable inductance in sequence.

Optionally, the bidirectionally controllable switch circuit includes two switch tubes connected in series; both of the two switch tubes are connected in parallel with a diode in anti-parallel; the two switch tubes are arranged on top of each other.

Optionally, the resonant circuit further includes a first inductor and a first capacitor; wherein,

The first end of the first inductor is connected to the first end of the inverter circuit, and the second end of the first inductor is connected to the first end of the controllable inductance unit;

The second end of the controllable inductance unit is connected to the third end of the inverter circuit;

The first end of the first capacitor is connected to the first end of the controllable inductance unit, and the second end of the first capacitor is connected to the second end of the controllable inductance unit;

Two ends of the first capacitor are respectively connected to the load as two output ends of the inverter.

Optionally, the resonant circuit further includes a first capacitor, a first inductor and a second capacitor; wherein,

The first end of the first inductor is connected to the first end of the inverter circuit, and the second end of the first inductor is connected to the first end of the first capacitor;

The second end of the first capacitor is respectively connected to the first end of the controllable inductance unit and the first end of the second capacitor;

The second end of the controllable inductance unit and the second end of the second capacitor are respectively connected to the third end of the inverter circuit;

The first end and the second end of the controllable inductance unit are respectively connected to both ends of the load as two output ends of the inverter.

Optionally, the resonant circuit further includes a first capacitor, a first inductor and a second capacitor; wherein,

The first end of the controllable inductance unit and the first end of the first capacitor are respectively connected to the first end of the inverter circuit;

The second end of the controllable inductance unit and the second end of the first capacitor are respectively connected to the first end of the second capacitor;

the second end of the second capacitor is connected to the first end of the first inductor;

The second end of the first inductor is connected to the third end of the inverter circuit;

The first end of the second capacitor and the second end of the first inductor are respectively connected to both ends of the load as two output ends of the inverter.

Optionally, the resonant circuit further includes a first capacitor, a first inductor and a second capacitor; wherein,

The first end of the first capacitor and the first end of the first inductor are respectively connected to the first end of the inverter circuit;

The second end of the first capacitor and the second end of the first inductor are respectively connected to the first end of the second capacitor, and the second end of the first capacitor and the first end of the first inductor are respectively connected. The two ends are respectively connected with the first end of the controllable inductance unit;

The second end of the second capacitor and the second end of the controllable inductance unit are respectively connected to the third end of the inverter circuit;

The first end and the second end of the controllable inductance unit are respectively connected to both ends of the load as two output ends of the inverter.

It can be seen from the above technical solutions that the high-frequency resonant inverter in the embodiment of the present invention includes an inverter circuit and a resonant circuit; the inverter circuit is respectively connected to the resonant circuit and an external DC power supply, and is used to convert the inverter according to the first control signal. The DC power supply is converted into a symmetrical square wave voltage, and the symmetrical square wave voltage is output to the resonant circuit. The preset carrier frequency and the modulating wave frequency are the same; the resonant circuit is connected to an external load, and is used to adjust the voltage gain under the control of the second control signal to convert the symmetrical square wave voltage into an expected The AC voltage is output to the load. In this embodiment, since the carrier frequency and the modulating wave frequency are the same, the high-power and high-frequency sinusoidal power supply requirements can be met, and the voltage gain can be dynamically adjusted through the resonant circuit.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative efforts.

FIG. 1 is a schematic diagram of a circuit structure of a high-frequency resonant inverter according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a circuit structure of a controllable capacitor unit according to an embodiment of the present invention.

FIG. 3 is a circuit diagram of a controllable capacitor unit according to an embodiment of the present invention.

4(a) to 4(d) are equivalent circuit diagrams of the controllable capacitor unit shown in FIG. 3 under four operating modes.

FIG. 5 is a schematic diagram of a circuit structure of a controllable inductance unit according to an embodiment of the present invention.

FIG. 6 is a circuit diagram of a controllable inductance unit according to an embodiment of the present invention.

7(a) to 7(c) are equivalent circuit diagrams of the controllable inductance unit shown in FIG. 6 under two operating modes.

FIG. 8 is a circuit diagram of a high-frequency resonant inverter implemented based on a controllable capacitor unit according to an embodiment of the present invention.

FIG. 9 is a circuit diagram of a high-frequency resonant inverter implemented based on a controllable capacitor unit according to another embodiment of the present invention.

FIG. 10 is a circuit diagram of a high-frequency resonant inverter implemented based on a controllable capacitor unit according to another embodiment of the present invention.

FIG. 11 is a circuit diagram of a high-frequency resonant inverter implemented based on a controllable capacitor unit according to another embodiment of the present invention.

FIG. 12 is a circuit diagram of a high-frequency resonant inverter implemented based on a controllable inductance unit according to another embodiment of the present invention.

FIG. 13 is a circuit diagram of a high-frequency resonant inverter implemented based on a controllable inductance unit according to another embodiment of the present invention.

FIG. 14 is a circuit diagram of a high-frequency resonant inverter implemented based on a controllable inductance unit according to another embodiment of the present invention.

FIG. 15 is a circuit diagram of a high-frequency resonant inverter implemented based on a controllable inductance unit according to another embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

In view of the problems existing in the related art, an embodiment of the present invention provides a high-frequency resonant inverter, the inventive concept of which is to add a resonant circuit on the basis of the inverter circuit, and output an expected AC voltage by adjusting the voltage gain of the resonant circuit to the load, and the output voltage gain can be dynamically adjusted.

The Fourier transform of the symmetrical square wave voltage output by the inverter circuit can be decomposed into a plurality of sine waves with different frequencies. In addition to the sine wave with the lowest frequency that is consistent with the switching frequency of the switching device, it also includes a frequency greater than A sine wave with a switching frequency that is a multiple of the switching frequency. In addition, the LC resonance has the following characteristics: the LC series resonance impedance is zero (equivalent to a short circuit), and the LC parallel impedance is infinite (equivalent to an open circuit). At the same time, the output gain of the sine wave of other frequencies obtained by Fourier transform decomposition tends to zero, and the sine wave of the target frequency can be output to the load, but the sine wave of the non-target frequency cannot be output to the load.

The inverter circuit is respectively connected with the resonant circuit and the external DC power supply, and is also connected with the first several control terminals, and is suitable for converting the DC power supply voltage under the control of the control signals connected to the first several control terminals. A symmetrical square wave voltage is formed, and the symmetrical square wave voltage is output to the resonant circuit.

The resonant circuit is connected to an external load, and is also connected to the second plurality of control terminals, and is suitable for controlling the voltage gain of the resonant circuit under the control of the control signals connected to the second plurality of control terminals, and the resonance circuit can be adjusted. The circuit converts the symmetrical square wave voltage into an expected AC voltage and outputs it to the load.

The frequency of the modulating wave of the preset inverter circuit is equal to the carrier frequency, so the frequency of the output symmetrical square wave voltage is equal to the switching frequency of the inverter circuit. The resonant circuit uses the characteristics of LC resonance to decompose the symmetrical square wave voltage by Fourier transform, and the sine wave whose frequency is equal to the switching frequency of the inverter circuit is output to the load, while the sine wave whose frequency is not equal to the switching frequency of the inverter circuit cannot be output to the load. . Therefore, the inverter provided by the present invention can output a high-frequency sine wave voltage with a frequency equal to the switching frequency.

Referring to FIG. 2 , the resonant circuit includes a controllable capacitor unit; the controllable capacitor unit includes at least a bidirectional controllable switch circuit and a controllable capacitor; wherein the first end of the bidirectional controllable switch circuit is connected to a controllable capacitor. The first end of the control capacitor is connected to the first end of the controllable capacitor unit; the second end of the bidirectional controllable switch circuit is connected to the second end of the controllable capacitor, and serves as the controllable capacitor unit at the same time the second end. The bidirectional controllable switch circuit is also connected to the second plurality of control terminals, and under the control of the control signals connected to the second plurality of control terminals, the controllable capacitor unit provides four working modes, so that all The equivalent capacitance value of the controllable capacitor in one switching cycle can be adjusted:

In the first working mode, current flows from the first end of the controllable capacitor unit to the second end of the controllable capacitor unit through the bidirectional controllable switch circuit, and the controllable capacitor does not work; the second works In the mode, current flows from the first end of the controllable capacitor unit to the second end of the controllable capacitor unit through the controllable capacitor, and the bidirectional controllable switch circuit is turned off;

In the third working mode, current flows from the second end of the controllable capacitor unit to the first end of the controllable capacitor unit through the bidirectional controllable switch circuit, and the controllable capacitor does not work;

In the fourth working mode, current flows from the second end of the controllable capacitor unit to the first end of the controllable capacitor unit through the controllable capacitor, and the bidirectional controllable switch circuit is turned off.

or,

Referring to FIG. 5 , the resonant circuit includes a controllable inductance unit, and the controllable inductance unit at least includes a bidirectional controllable switch circuit and a controllable inductance connected in series. Wherein, the first end of the bidirectional controllable switch circuit is connected to the second end of the controllable inductance, the first end of the controllable inductance serves as the first end of the controllable inductance unit, and the bidirectional controllable inductance unit is The second end of the controllable switch circuit is used as the second end of the controllable inductance unit. The bidirectional controllable switch circuit is also connected to the second plurality of control terminals, and under the control of the control signals connected to the second plurality of control terminals, the controllable inductance unit provides three working modes, so that all the The equivalent inductance value of the controllable inductance in one switching cycle can be adjusted:

In the first working mode, current flows from the first end of the controllable inductance unit to the second end of the controllable inductance unit through the controllable inductance and the bidirectional controllable switch circuit in sequence;

In the second working mode, the bidirectional controllable switch circuit is turned off, and no current flows through the controllable inductance unit;

In the third working mode, current flows from the second end of the controllable inductance unit to the first end of the controllable inductance unit through the bidirectional controllable switch circuit and the controllable inductance in sequence. Another embodiment of the present invention provides a specific circuit diagram of a controllable capacitance unit and a controllable inductance unit, and the above resonant circuit can be implemented based on the provided controllable capacitance unit or controllable inductance unit and other related devices.

It should be noted that, for the convenience of description, the switch MOSFET is used to represent the controllable (on and off) switch in the present invention, but the switch in the present invention is not limited to the MOSFET. An N-channel MOSFET is used as an example for description. The first terminal of the N-channel MOSFET refers to the drain, the second terminal refers to the source, and the control terminal refers to the gate. A drive control signal is applied to the control terminal of each switch in the present invention. For the sake of brevity, no further description will be given later. The switch in the present invention can also be implemented by other controllable switch devices other than MOSFET, such as IGBT.

Note that a diode is used to represent a unidirectional conduction element, but the unidirectional conduction element in the present invention is not limited to a diode. The positive pole of the diode is the anode and the negative pole is the cathode. The unidirectional conduction element in the present invention may also adopt other unidirectional conduction devices other than diodes. In addition, "first", "second", etc. are only used to distinguish each device, and do not limit the order of each device.

Referring to FIG. 3 , the controllable capacitor unit includes a controllable capacitor Cs, a first switch tube S ₁ and a second switch tube S ₂ which are connected in series. Both the first switch S ₁ and the second switch S ₂ are connected in parallel with a diode in reverse, and the first switch S ₁ and the second switch S ₂ are connected to top of each other. Specifically, the first end of the first switch S1 is used as the _first end of the controllable capacitor unit (represented by the symbol A), the second end of the _first switch S1 and the second end of the _second switch S2 connect. The first end (the right end in FIG. 3 ) of the _second switch tube S2 serves as the second end of the controllable capacitor unit (represented by the symbol B). The first end of the controllable capacitor Cs (the left end in FIG. 3 ) is connected to the first end of the _first switch S1, and the second end of the controllable capacitor Cs is connected to the first end of the _second switch S2. The control terminal of the _first switch tube S1 and the control terminal of the _second switch tube S2 are respectively connected to the controller so as to access the second control signal.

In one switching cycle, the controllable capacitor unit provides four operating modes under the control of the second control signal connected in, as follows:

Working mode ₁ : the first switch S1 is turned on, the _first switch S1 anti-parallel diode is turned off, the _second switch S2 is turned off, the _second switch S2 anti-parallel diode is turned on, and the equivalent circuit As shown in Figure 4(a). At this time, the current flows from A to B, and sequentially passes through the first switch S ₁ and the anti-parallel diode of the second switch S ₂ . The switch branch (S ₁ , S ₂ anti-parallel diodes) connected in parallel with the controllable capacitor Cs is equivalent to a short circuit, so the controllable capacitor Cs does not work, that is, the equivalent capacitance value of the controllable capacitor Cs is infinite at this time.

In the second working mode, the first switch S ₁ , the second switch S ₂ and their anti-parallel diodes are all turned off, the controllable capacitor Cs works, and the equivalent circuit is shown in FIG. 4( c ). Current flows from A to B via a controllable capacitor Cs. At this time, the equivalent capacitance value of the controllable capacitor Cs is its own capacitance value.

Working mode three, the _first switch S1 is turned off, the _first switch S1 anti-parallel diode is turned on, the _second switch S2 is turned on, the _second switch S2 anti-parallel diode is turned off, and the equivalent circuit As shown in Figure 4(c). At this time, the current flows from B to A, and sequentially passes through the second switch tube and the anti-parallel diode of the _first switch tube S1. . The switch branch (S ₂ , S ₁ anti-parallel diodes) connected in parallel with the controllable capacitor Cs is equivalent to a short circuit, so the controllable capacitor Cs does not work, that is, the equivalent capacitance value of the controllable capacitor Cs is infinite at this time.

Working mode 4, the _first switch S1, the _second switch S2 and their anti-parallel diodes are all turned off, the controllable capacitor Cs works, and the equivalent circuit is shown in Figure 4(d). Current flows from B to A via a controllable capacitor Cs. At this time, the equivalent capacitance value of the controllable capacitor Cs is its own capacitance value.

From the analysis of the above four operating modes, it can be known that the equivalent capacitance values in Mode 1 and Mode 3 are infinite, and the equivalent capacitance values in Mode 2 and Mode 4 are the capacitance values of the controllable capacitor itself. By controlling the switching transistors S1 and S2 to be turned _on or off, the controllable capacitor unit shown in FIG. ₃ operates alternately in a certain combination in the above-mentioned four operating modes, thereby obtaining the required equivalent capacitance value. The specific combination form of the four working modes depends on the specific modulation strategy adopted in practical applications, and will not be described here.

By combining the four operating modes of the controllable capacitor unit in a certain order and controlling the turn-on or turn-off time of the switch tubes S ₁ and S ₂ in each mode, the controllable capacitor unit is regulated within one switching cycle Therefore, the impedance value of the controllable capacitor unit is adjusted, that is, the voltage across the controllable capacitor unit is adjusted. According to the resonant circuit structure provided by the present invention, regulating the voltage across the controllable capacitor unit is equivalent to regulating the output voltage. Therefore, the voltage gain of the high-frequency resonance inverter provided by the present invention can be adjusted. Note that the voltage gain is the ratio of the magnitude of the output voltage to the magnitude of the input voltage.

Referring to FIG. 6 , the controllable inductance unit includes a controllable inductance Ls, a first switch tube S ₁ and a second switch tube S ₂ connected in series. Both the first switch S ₁ and the second switch S ₂ are connected in parallel with a diode in reverse, and the first switch S ₁ and the second switch S ₂ are connected to top of each other. Specifically, the second end of the second switch tube S2 is connected to the _second end of the _first switch tube S1, and the first end of the controllable inductance Ls is used as the first end of the controllable inductance unit (represented by the symbol A); The first end of the _first switch tube S1 is connected to the second end of the controllable inductor Ls. The first end of the second switch tube S2 serves as the _second end of the controllable inductance unit (represented by the symbol B). The control terminal of the _first switch tube S1 and the control terminal of the _second switch tube S2 are respectively connected to the controller so as to access the second control signal.

In one switching cycle, the controllable inductance unit provides three working modes under the control of the connected second control signal, as follows:

Working mode ₁ , the first switch S1 is turned on, the _first switch S1 anti-parallel diode is turned off, the _second switch S2 is turned off, the _second switch S2 anti-parallel diode is turned on, and the equivalent circuit As shown in Figure 7(a). The current I _AB passes through the anti-parallel diodes of the controllable inductance Ls, the switch tube S ₁ and the switch tube S ₂ in sequence. At this time, the equivalent inductance value of the controllable inductance Ls is the inductance value of the controllable inductance Ls itself.

In working mode 2, the first switch S ₁ , the second switch S ₂ and their anti-parallel diodes are all turned off, the controllable inductor Ls does not work, and the equivalent circuit is shown in Figure 7(b). At this time, no current flows through the controllable inductance unit, and the equivalent inductance value of the controllable inductance Ls is infinite.

Working mode three, the _first switch S1 is turned off, the _first switch S1 anti-parallel diode is turned on, the _second switch S2 is turned on, the _second switch S2 anti-parallel diode is turned off, and the equivalent circuit As shown in Figure 7(c). The current I _BA sequentially passes through the switch tube S ₂ , the anti-parallel diode of the switch tube S ₁ , and the controllable inductance Ls. At this time, the equivalent inductance value of the controllable inductance Ls is the inductance value of the controllable inductance Ls itself.

From the analysis of the above three operating modes, it can be known that the equivalent inductance value in mode 1 and mode 3 is the inductance value of the controllable inductor itself, and the equivalent inductance value in mode 2 is infinite. By controlling the switches S1 and S2 to be turned _on or off, the controllable inductance unit shown in FIG. ₆ operates alternately in a certain combination in the above three operating modes, thereby obtaining the required equivalent inductance value. The specific combination form of the three working modes depends on the specific modulation strategy adopted in practical applications, and will not be described here.

By combining the four operating modes of the controllable inductance unit in a certain order and controlling the turn-on or turn _- off time _of the switches S1 and S2 in each mode, the controllable inductance unit is regulated within one switching cycle The equivalent inductance value of the controllable inductance unit is adjusted to adjust the impedance value of the controllable inductance unit, that is, the voltage across the controllable inductance unit is adjusted. According to the resonant circuit structure provided by the present invention, it can be known that regulating the voltage across the controllable inductance unit is equivalent to regulating the output voltage. Therefore, the voltage gain of the high-frequency resonance inverter provided by the present invention can be adjusted.

Combining the above-mentioned controllable capacitance unit and controllable inductance unit, the present invention provides the following embodiments to help further understand the high-frequency resonant inverter provided by the present invention.

Example 1

Embodiments of the present invention provide a high-frequency resonant inverter. Referring to FIG. 8 , the high-frequency resonant inverter includes an inverter circuit I and a resonant circuit II. The inverter circuit I converts the DC power voltage into a symmetrical square wave voltage. The symmetrical square wave voltage is transformed into an expected sinusoidal AC voltage through the resonant branch II.

The frequency of the modulating wave of the preset inverter circuit is equal to the carrier frequency, so the frequency of the output symmetrical square wave voltage is equal to the switching frequency of the inverter circuit. The resonant circuit utilizes the characteristics of LC resonance to decompose the symmetrical square wave voltage through Fourier transform, and the sine wave whose frequency is equal to the switching frequency of the inverter circuit is output to the load, while the sine wave whose frequency is not equal to the switching frequency of the inverter circuit cannot be output. to the load. Therefore, the inverter provided by the present invention can output a high-frequency sine wave voltage with a frequency equal to the switching frequency.

The inverter circuit I includes a bridge circuit formed by four switching tubes, the second end of the bridge circuit is connected to the positive pole of the DC power supply, the fourth end is connected to the negative pole of the DC power supply, and the first end is connected to the first terminal of the resonant circuit II. One end is connected, and the third end is connected to the second end of the resonant circuit II.

Taking the circuit shown in Figure 8 as an example, the working mode of the inverter circuit: the voltage value of the DC power supply is Vin. When the switch tube T1 and the switch tube T4 are turned on, the output voltage value is Vin and the direction is positive; when the switch tube T2 and the switch tube T3 are turned on, the output voltage value is Vin and the direction is negative; the switch tube T1 and the switch tube T3 When turned on, the output voltage value is zero; when the switch tube T2 and the switch tube T4 are turned on, the output voltage value is zero.

The resonant circuit II includes a controllable capacitance unit, a first inductance Ls and a first capacitance Cp. The first end of the first inductance Ls serves as the first end of the resonant circuit and is connected to the first end of the inverter circuit I, and the second end of the first inductance Ls is connected to the first end of the controllable capacitor unit (marked by A) . The second end of the controllable capacitor unit (represented by the symbol B) is connected to the first end of the first capacitor Cp, and the second end of the first capacitor Cp is connected to the third end of the inverter circuit I as the second end of the resonant circuit; Two ends of the first capacitor Cp are respectively connected to two ends of the load as two output ends of the inverter.

In the resonant circuit II, the controllable capacitor Cs and the first inductor Ls resonate in series at the first resonant frequency, and the controllable capacitor Cs, the first inductor Ls and the first capacitor Cp resonate in series at the second resonant frequency. The specific values of the first resonant frequency and the second resonant frequency depend on the requirements of practical applications, and will not be repeated here.

The controllable capacitor unit realizes that the equivalent capacitance value of the controllable capacitor Cs in one switching cycle can be adjusted by controlling the _on and off _of the switch tubes S1 and S2, that is, the equivalent capacitance of the controllable capacitor Cs in one switching cycle. The capacitance value can be adjusted according to actual needs, and the method for changing the capacitance value is to control the _on and off _of the switches S1 and S2. That is to say, the equivalent capacitance value of the controllable capacitor Cs in one switching cycle can be adjusted.

To sum up, the controllable capacitance Cs is regulated by combining the four operating modes of the controllable inductance unit in a certain order and controlling the turn-on or turn-off time of the switches S ₁ and S ₂ in each mode. The equivalent capacitance value in one switching cycle, thereby regulating the impedance value of the controllable capacitance unit, and then regulating the voltage across the controllable capacitance unit. According to the circuit structure provided by the embodiments of the present invention, the controllable capacitor unit is connected in series with the load at the output end, and regulating the voltage across the controllable capacitor unit is equivalent to regulating the output voltage. Therefore, the voltage gain of the high-frequency resonance inverter provided by the present invention can be adjusted.

Embodiment 2

Embodiments of the present invention provide a high-frequency resonant inverter. Referring to FIG. 9 , the high-frequency switching controllable resonant inverter includes an inverter circuit I and a resonant circuit II.

Among them, the circuit composition, structure and working principle of the inverter circuit I are the same as those in FIG. 8 , and will not be repeated here. Similarly, the embodiments provided by the present invention only focus on the parts that are different from other embodiments, and the parts with the same circuit composition, structure and working principle will not be repeated.

The resonant circuit II includes a controllable capacitor unit, a first inductor Ls, a second inductor Lp and a first capacitor Cp. The first end of the first inductance Ls is connected to the first end of the inverter circuit I, and the second end of the first inductance Ls is connected to the first end A of the controllable capacitance unit; The second end of the capacitor control unit is respectively connected to the first end of the second inductor Lp and the first end of the first capacitor Cp; the second end of the second inductor Lp and the first end of the first capacitor Cp The second end is respectively connected with the third end of the inverter circuit I; the two ends of the first capacitor Cp are respectively connected with the two ends of the load as two output ends of the inverter.

In the resonant circuit II, the controllable capacitor Cs and the first inductor Ls resonate in series at the first resonant frequency, the second inductor Lp and the first capacitor Cp resonate in parallel at the second resonant frequency, and the controllable capacitor Cs and the first inductor Ls resonate in parallel. , the second inductor Lp and the first capacitor Cp resonate at the third resonance frequency. The specific values of the first resonant frequency, the second resonant frequency, and the third resonant frequency depend on the requirements of practical applications, and are not described here.

The principle of voltage gain regulation and the circuit composition and working mode of the inverter circuit I can refer to the first embodiment.

Embodiment 3

An embodiment of the present invention provides a high-frequency resonant inverter, see FIG. 10 . The high-frequency switching controllable resonant inverter includes an inverter circuit I and a resonant circuit II.

The resonant circuit II includes a controllable capacitor unit, a first inductor Ls, a second inductor Lp and a first capacitor Cp. Wherein, the first end of the first inductor Ls is connected to the first end of the inverter circuit I, and the second end of the first inductor Ls is connected to the first end of the controllable capacitor unit; the The second end of the controllable capacitor unit is connected to the first end of the first capacitor Cp; the second end of the first capacitor Cp is connected to the first end of the second inductor Lp; the second inductor Lp The second end of the inverter is connected to the third end of the inverter circuit I; the first end of the first capacitor Cp and the second end of the second inductor Lp are used as the two output ends of the inverter, respectively. Connect to both ends of the load.

In the resonant circuit II, the controllable capacitor Cs and the first inductor Ls resonate in series at the first resonant frequency, the second inductor Lp and the first capacitor Cp resonate in series at the second resonant frequency, the controllable capacitor Cs, the first inductor Ls , the second inductor Lp and the first capacitor Cp resonate at the third resonance frequency.

The principle of voltage gain regulation and the circuit composition and working mode of the inverter circuit I can refer to the first embodiment.

Embodiment 4

Embodiments of the present invention provide a high-frequency resonant inverter. Referring to FIG. 11 , the high-frequency resonant inverter includes an inverter circuit I and a resonant circuit II.

Wherein, the resonant circuit II includes a controllable capacitance unit, a first inductance Ls, a second inductance Lp and a first capacitance Cs. Wherein, the first end of the first inductor Ls is connected to the first end of the inverter circuit I, and the second end of the first inductor Ls is connected to the first end of the first capacitor Cs; the The second end of the first capacitor Cs is connected to the first end of the controllable capacitor unit; the second end of the controllable capacitor unit is connected to the first end of the second inductor Lp; the second inductor Lp The second end of Lp is connected to the third end of the inverter circuit I; the first end of the controllable capacitor unit and the second end of the second inductor Lp are used as the two output ends of the inverter, respectively Connect to both ends of the load.

In the resonant circuit II, the first inductor Ls and the first capacitor Cs resonate in series at the first resonant frequency, the controllable capacitor Cp and the second inductor Lp resonate in series at the second resonant frequency, and the controllable capacitor Cp and the first inductor Ls resonate in series. , the second inductor Lp and the first capacitor Cs resonate in series at the third resonant frequency. For the principle of voltage gain regulation, reference may be made to Embodiment 1, which will not be repeated here.

Embodiment 5

Embodiments of the present invention provide a high-frequency resonant inverter and a control method thereof. Referring to FIG. 12 , the high-frequency switching controllable resonant inverter includes an inverter circuit I and a resonant circuit II.

The resonance circuit II includes a controllable inductance unit, a first inductance Ls and a first capacitance Cp. The first end of the first inductance Ls is connected to the first end of the inverter circuit I, and the second end of the first inductance Ls is connected to the first end A of the controllable inductance unit. The second end of the controllable inductance unit is connected to the third end of the inverter circuit I. The first capacitor Cp is connected in parallel with the controllable inductance unit; the two ends of the first capacitor Cp are respectively connected to the two ends of the load as two output ends of the inverter.

In the resonant circuit II, the controllable inductance Lp and the first capacitor Cp resonate in parallel at the first resonant frequency, and the first inductance Ls, the controllable inductance Lp and the first capacitor Cp resonate at the second resonant frequency.

The controllable inductance unit realizes that the equivalent inductance value of the controllable inductance Lp in one switching cycle can be adjusted by controlling the turn-on and turn-off of the _two switches S1 and S2, that is, the controllable inductance Lp in _one switching cycle. The equivalent inductance value can be changed according to actual needs. The method of changing the inductance value of the controllable inductance Lp is to control the _on and off _of the switch tubes S1 and S2. That is to say, the equivalent inductance value of the controllable inductance Lp in one switching cycle is regulated by controlling the on and off _of the switching transistors S1 and S2, thereby regulating the voltage gain of the resonant circuit _II .

Embodiment 6

Embodiments of the present invention provide a high-frequency resonant inverter. Referring to FIG. 13 , the high-frequency resonant inverter includes an inverter circuit I and a resonant circuit II.

Wherein, the resonant circuit II includes a controllable inductance unit, a first capacitor Cs, a first inductor Ls and a second capacitor Cp. Wherein, the first end of the first inductor Ls is connected to the first end of the inverter circuit I, and the second end of the first inductor Ls is connected to the first end of the first capacitor Cs; the The second end of the first capacitor Cs is respectively connected to the first end of the controllable inductance unit and the first end of the second capacitor Cp; the second end of the controllable inductance unit and the second capacitor Cp The second end of the inverter circuit I is respectively connected to the third end; the first end and the second end of the controllable inductance unit are respectively connected to both ends of the load as the two output ends of the inverter.

In the resonant circuit II, the first inductor Ls and the first capacitor Cs resonate in series at the first resonant frequency, the second capacitor Cp and the controllable inductor Lp resonate in parallel at the second resonant frequency, and the controllable capacitor Cp and the first inductor Ls resonate in parallel. , the second inductor Lp and the first capacitor Cs resonate at the third resonance frequency. For the principle of voltage gain regulation, reference may be made to the fifth embodiment, which will not be repeated here.

Embodiment 7

Embodiments of the present invention provide a high-frequency resonant inverter. Referring to FIG. 14 , the high-frequency resonant inverter includes an inverter circuit I and a resonant circuit II.

Wherein, the resonant circuit II includes a controllable inductance unit, a first capacitor Cs, a first inductor Lp and a second capacitor Cp. Wherein, the first end of the controllable inductance unit and the first end of the first capacitor Cs are respectively connected to the first end of the inverter circuit I; the second end of the controllable inductance unit and the The second ends of the first capacitor Cs are respectively connected to the first ends of the second capacitor Cp; the second end of the second capacitor Cp is connected to the first end of the first inductor Lp; the first inductor The second end of Lp is connected to the third end of the inverter circuit I; the first end of the second capacitor Cp and the second end of the first inductor Lp serve as two output ends of the inverter Connect to both ends of the load respectively.

In the resonant circuit II, the controllable inductance Ls and the first capacitor Cs resonate in parallel at the first resonant frequency, the first inductance Lp and the second capacitor Cp resonate in parallel at the second resonant frequency, the controllable inductance Ls, the first capacitor Cs , the first inductor Lp and the second capacitor Cp resonate at the third resonance frequency. For the principle of voltage gain regulation, reference may be made to the fifth embodiment, which will not be repeated here.

Embodiment 8

Embodiments of the present invention provide a high-frequency resonant inverter. Referring to FIG. 15 , the high-frequency resonant inverter includes an inverter circuit I and a resonant circuit II.

Wherein, the resonant circuit II includes a controllable inductance unit, a first capacitor Cs, a first inductor Ls and a second capacitor Cp. The first end of the first capacitor Cs and the first end of the first inductor Ls are respectively connected to the first end of the inverter circuit I; the second end of the first capacitor Cs and the The second end of the first inductor Ls is respectively connected to the first end of the second capacitor Cp, and the second end of the first capacitor Cs and the second end of the first inductor Ls are respectively connected to the controllable The first end of the inductance unit is connected; the second end of the second capacitor Cp and the second end of the controllable inductance unit are respectively connected to the third end of the inverter circuit I; the The first end and the second end are respectively connected to two ends of the load as two output ends of the inverter.

In the resonant circuit II, the first capacitor Cs and the first inductor Ls resonate in parallel at the first resonant frequency, the controllable inductor Lp and the second capacitor Cp resonate in parallel at the second resonant frequency, and the controllable inductor Lp and the first capacitor Cs resonate in parallel. , the first inductor Ls and the second capacitor Cp resonate at the third resonance frequency. For the principle of voltage gain regulation, reference may be made to the fifth embodiment, which will not be repeated here.

The above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that it is still possible to implement the foregoing embodiments. The technical solutions described in the examples are modified, or some or all of the technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. within the scope of the claims and description of the invention.

Claims (13)

1. A high-frequency resonant inverter, characterized in that, comprising an inverter circuit and a resonant circuit; The inverter circuit is respectively connected with the resonant circuit and the external DC power supply, and is also connected with the first several control terminals, and is suitable for converting the DC power supply voltage under the control of the control signals connected to the first several control terminals. forming a symmetrical square wave voltage, and outputting the symmetrical square wave voltage to the resonant circuit; The resonant circuit is connected to an external load, and is also connected to the second plurality of control terminals, and is suitable for controlling the voltage gain of the resonant circuit under the control of the control signals connected to the second plurality of control terminals, and the resonance circuit can be adjusted. The circuit converts the symmetrical square wave voltage into an expected AC voltage and outputs it to the load. 2 . The high-frequency resonant inverter according to claim 1 , wherein the resonant circuit comprises a controllable capacitor unit; the controllable capacitor unit at least comprises a bidirectional controllable switch circuit and a controllable capacitor 2 . ; wherein, the first end of the bidirectional controllable switch circuit is connected to the first end of the controllable capacitor, and simultaneously serves as the first end of the controllable capacitor unit; the second end of the bidirectional controllable switch circuit is connected to the controllable capacitor. The second end of the control capacitor is connected and simultaneously serves as the second end of the controllable capacitor unit; The bidirectional controllable switch circuit is also connected to the second plurality of control terminals, and under the control of the control signals connected to the second plurality of control terminals, the controllable capacitor unit provides four working modes, so that all The equivalent capacitance value of the controllable capacitor in one switching cycle can be adjusted: In the first working mode, current flows from the first end of the controllable capacitor unit to the second end of the controllable capacitor unit through the bidirectional controllable switch circuit, and the controllable capacitor does not work; the second works In the mode, current flows from the first end of the controllable capacitor unit to the second end of the controllable capacitor unit through the controllable capacitor, and the bidirectional controllable switch circuit is turned off; In the third working mode, current flows from the second end of the controllable capacitor unit to the first end of the controllable capacitor unit through the bidirectional controllable switch circuit, and the controllable capacitor does not work; In the fourth working mode, current flows from the second end of the controllable capacitor unit to the first end of the controllable capacitor unit through the controllable capacitor, and the bidirectional controllable switch circuit is turned off. 3 . The high-frequency resonant inverter according to claim 2 , wherein the bidirectionally controllable switch circuit comprises two switch tubes connected in series; and each of the two switch tubes is connected with a diode in anti-parallel. 4 . ; The two switch tubes are arranged on top of each other. 4. The high-frequency resonant inverter according to claim 2 or 3, wherein the resonant circuit further comprises a first inductor and a first capacitor; wherein, The first end of the first inductor is connected to the first end of the inverter circuit, and the second end of the first inductor is connected to the first end of the controllable capacitance unit; The second end of the controllable capacitor unit is connected to the first end of the first capacitor, and the second end of the first capacitor is connected to the third end of the inverter circuit; Two ends of the first capacitor are respectively connected to two ends of the load as two output ends of the inverter. 5. The high-frequency resonant inverter according to claim 2 or 3, wherein the resonant circuit further comprises a first inductor, a second inductor and a first capacitor; wherein, The first end of the first inductor is connected to the first end of the inverter circuit, and the second end of the first inductor is connected to the first end of the controllable capacitance unit; The second end of the controllable capacitor unit is respectively connected to the first end of the second inductor and the first end of the first capacitor; The second end of the second inductor and the second end of the first capacitor are respectively connected to the third end of the inverter circuit; Two ends of the first capacitor are respectively connected to two ends of the load as two output ends of the inverter. 6. The high-frequency resonant inverter according to claim 2 or 3, wherein the resonant circuit further comprises a first inductor, a second inductor and a first capacitor; wherein, The first end of the first inductor is connected to the first end of the inverter circuit, and the second end of the first inductor is connected to the first end of the controllable capacitance unit; the second end of the controllable capacitor unit is connected to the first end of the first capacitor; the second end of the first capacitor is connected to the first end of the second inductor; The second end of the second inductor is connected to the third end of the inverter circuit; The first end of the first capacitor and the second end of the second inductor are respectively connected to both ends of the load as two output ends of the inverter. 7. The high-frequency resonant inverter according to claim 2 or 3, wherein the resonant circuit further comprises a first inductor, a second inductor and a first capacitor; wherein, The first end of the first inductor is connected to the first end of the inverter circuit, and the second end of the first inductor is connected to the first end of the first capacitor; the second end of the first capacitor is connected to the first end of the controllable capacitor unit; the second end of the controllable capacitance unit is connected to the first end of the second inductor; The second end of the second inductor is connected to the third end of the inverter circuit; The first end of the controllable capacitance unit and the second end of the second inductance are respectively connected to both ends of the load as two output ends of the inverter. 8 . The high-frequency resonant inverter according to claim 1 , wherein the resonant circuit comprises a controllable inductance unit; the controllable inductance unit at least comprises a bidirectional controllable switch circuit and a controllable inductor; where, The first end of the bidirectional controllable switch circuit is connected to the second end of the controllable inductance, the first end of the controllable inductance serves as the first end of the controllable inductance unit, and the bidirectional controllable switch The second end of the circuit is used as the second end of the controllable inductance unit; The bidirectional controllable switch circuit is also connected to the second plurality of control terminals, and under the control of the control signals connected to the second plurality of control terminals, the controllable inductance unit provides three working modes, so that all the The equivalent inductance value of the controllable inductance in one switching cycle can be adjusted: In the first working mode, current flows from the first end of the controllable inductance unit to the second end of the controllable inductance unit through the controllable inductance and the bidirectional controllable switch circuit in sequence; In the second working mode, the bidirectional controllable switch circuit is turned off, and no current flows through the controllable inductance unit; In the third working mode, current flows from the second end of the controllable inductance unit to the first end of the controllable inductance unit through the bidirectional controllable switch circuit and the controllable inductance in sequence. 9 . The high-frequency resonant inverter according to claim 8 , wherein the bidirectionally controllable switch circuit comprises two switch tubes connected in series; and each of the two switch tubes is connected with a diode in anti-parallel. 10 . ; The two switch tubes are arranged on top of each other. 10. The high-frequency resonant inverter according to claim 8 or 9, wherein the resonant circuit further comprises a first inductor and a first capacitor; wherein, The first end of the first inductor is connected to the first end of the inverter circuit, and the second end of the first inductor is connected to the first end of the controllable inductance unit; The second end of the controllable inductance unit is connected to the third end of the inverter circuit; The first end of the first capacitor is connected to the first end of the controllable inductance unit, and the second end of the first capacitor is connected to the second end of the controllable inductance unit; Two ends of the first capacitor are respectively connected to two ends of the load as two output ends of the inverter. 11. The high-frequency resonant inverter according to claim 8 or 9, wherein the resonant circuit further comprises a first capacitor, a first inductor and a second capacitor; wherein, The first end of the first inductor is connected to the first end of the inverter circuit, and the second end of the first inductor is connected to the first end of the first capacitor; The second end of the first capacitor is respectively connected to the first end of the controllable inductance unit and the first end of the second capacitor; The second end of the controllable inductance unit and the second end of the second capacitor are respectively connected to the third end of the inverter circuit; The first end and the second end of the controllable inductance unit are respectively connected to both ends of the load as two output ends of the inverter. 12. The high-frequency resonant inverter according to claim 8 or 9, wherein the resonant circuit further comprises a first capacitor, a first inductor and a second capacitor; wherein, The first end of the controllable inductance unit and the first end of the first capacitor are respectively connected to the first end of the inverter circuit; The second end of the controllable inductance unit and the second end of the first capacitor are respectively connected to the first end of the second capacitor; the second end of the second capacitor is connected to the first end of the first inductor; The second end of the first inductor is connected to the third end of the inverter circuit; The first end of the second capacitor and the second end of the first inductor are respectively connected to both ends of the load as two output ends of the inverter. 13. The high-frequency resonant inverter according to claim 8 or 9, wherein the resonant circuit further comprises a first capacitor, a first inductor and a second capacitor; wherein, The first end of the first capacitor and the first end of the first inductor are respectively connected to the first end of the inverter circuit; The second end of the first capacitor and the second end of the first inductor are respectively connected to the first end of the second capacitor, and the second end of the first capacitor and the first end of the first inductor are respectively connected. The two ends are respectively connected with the first end of the controllable inductance unit; The second end of the second capacitor and the second end of the controllable inductance unit are respectively connected to the third end of the inverter circuit; The first end and the second end of the controllable inductance unit are respectively connected to both ends of the load as two output ends of the inverter.

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