CN101478256A - Soft switch welding inverter, phase-shifting control method and soft switching method - Google Patents

Abstract

The invention discloses a soft-switch welding inverter power supply, a phase-shift control method and a soft-switch method, belonging to the field of electronic circuits. The soft-switching welding inverter power supply includes a full-bridge converter and a control module; the phase-shift control method is applied to the power supply, including: the control module receives the current signal of the full-bridge converter, and according to the The current signal is used to adjust the dead time of the phase-shifting signal; the soft switching method is applied to the power supply, including: connecting an auxiliary resonant network in parallel on the bridge arm of the power supply to provide auxiliary energy for the zero-voltage turn-on of the switching device; Before the switching device of the lagging arm of the full-bridge converter is turned off, the main power loop current flowing through the switching device is attenuated, and the reversal of the main power loop current is suppressed; the absorbing capacitor is connected in parallel on the switching device to slow down the switching device off The rate of voltage rise when withstand. The invention realizes the zero-voltage and zero-current soft switch in the full load range of the power supply including no-load and short-circuit.

Description

A soft-switching welding inverter power supply, a phase-shift control method, and a soft-switching method

technical field

The invention relates to the field of electronic circuits, in particular to a soft-switch welding inverter power supply, a phase-shift control method and a soft-switch method.

Background technique

Ordinary bipolar control full-bridge power converter, no matter the transformer secondary adopts full-wave rectification, bridge rectification, or current doubler rectification, as shown in Figure 1, it adopts traditional PWM (Pulse Width Modulation, pulse width modulation) control Technology realizes the control of the output characteristics of the power supply. The primary switching device of the transformer works in a hard switching state. The switching device bears a large voltage and current stress and has a large switching loss, which not only reduces the efficiency of the power supply, but also generates large EMI ( ElectroMagnetic Interference, electromagnetic interference), affecting the reliability of power supply work.

Combining soft switching technology with inverter technology is one of the important development directions of welding power supply. Realizing the soft switching of power switching devices can reduce switching losses, improve circuit efficiency, and help increase operating frequency, thereby increasing power density, while reducing voltage and current stress and EMI borne by switching devices, and improving power supply reliability. However, due to the wide working range of the welding power supply, the existence of no-load and short-circuit, and the dynamic and sharp changes of the power supply load, when applying soft-switching technology to the welding inverter power supply, the following key issues must be solved: to achieve the power of the full load range Soft switching of the switching device; guarantee the soft switching of the power switching device under two extreme working conditions of no-load and short circuit; maintain the soft switching of the power switching device during the dynamic change of the power supply load.

The phase-shift control of the full-bridge power conversion circuit is an effective method to realize the zero-voltage soft switching of the power switching device. The pressure soft switch has been widely used in medium and high power DC/DC (Direct Current, direct current) conversion. However, the basic phase-shift control full-bridge zero-voltage soft-switching converter has the problem that the soft-switching load range of the switching device is limited, especially the lagging arm, and the zero-voltage soft switching of the switching device cannot be realized at light load.

In order to broaden the zero-voltage soft-switching load range of the phase-shift control full-bridge power conversion circuit, many improved circuit topologies have emerged on the basis of the basic phase-shift control full-bridge inverter circuit.

The key to realizing zero-voltage switching of the lagging arm with a wide load range is energy. According to different energy sources, the circuit topology can be divided into two categories: one is to slow down the energy loss and use the original energy of the circuit to realize the zero-voltage switching of the lagging arm, such as The primary or secondary of the transformer is connected in series with a saturated inductance, and the LCD auxiliary resonant network is connected between the primary and the lagging arm of the transformer. LC or LCD auxiliary resonant network, etc.

The so-called zero-current turn-off of the lagging arm is to take effective measures to attenuate the primary current of the transformer to zero and keep it until the switching device is turned off during the phase-shift control of the circulating current of the full-bridge circuit. The circuit topology can also be divided into two categories. One is that after the primary current of the transformer decays to zero during the circulating current process, the current has a reverse trend. Series saturated inductors or diodes, etc.; the other is that after the transformer primary current decays to zero, the current is automatically kept at zero, such as transformer secondary passive clamping, active clamping, transformer primary adding auxiliary transformer network, etc.

In the process of realizing the present invention, the inventor finds that there are at least the following problems in the prior art:

Many existing improved full-bridge soft-switching circuit topologies broaden the zero-voltage soft-switching load range of the two arms or adopt zero-current soft switching for the lagging arm, but few of them can realize the full-load range of the two arms including the no-load state. Soft switching of power switching devices.

Contents of the invention

In order to realize zero-voltage and zero-current soft switching in the full load range including two extreme working states of no-load and short circuit, and maintain soft switching during the dynamic change of power supply load, the invention provides a soft-switching welding inverter power supply, phase-shift control method, and soft-switching method. Described technical scheme is as follows:

A soft-switching welding inverter power supply, including: a full-bridge converter and a control module;

The full bridge converter includes:

A first absorbing capacitor and a third absorbing capacitor, the first absorbing capacitor is connected in parallel to the first switching device of the super forearm of the full-bridge converter, and the third absorbing capacitor is connected in parallel to the super-forearm of the full-bridge converter On the third switching device of the forearm, the first snubber capacitor and the third snubber capacitor are used to jointly realize the zero-voltage turn-off of the full load range of the first switching device and the third switching device;

a super-forearm auxiliary resonant network connected in parallel to the super-forearm of the full-bridge converter, and used to realize zero-voltage turn-on of the full load range of the first switching device and the third switching device;

The control module includes:

A phase-shift control unit for adaptive adjustment of dead time, used to receive the current signal of the full-bridge converter, adjust the dead time of the phase-shift signal according to the current signal, and use the adjusted phase-shift signal as a control signal .

The full bridge transformer also includes:

A second absorbing capacitor and a fourth absorbing capacitor, the second absorbing capacitor is connected in parallel to the second switching device of the lagging arm of the full-bridge converter, and the fourth absorbing capacitor is connected in parallel to the hysteresis of the full-bridge converter On the fourth switching device of the arm, the second snubber capacitor and the fourth snubber capacitor are used to jointly realize the zero-voltage turn-off of the full load range of the second switching device and the fourth switching device;

A lagging arm auxiliary resonant network, connected in parallel to the lagging arm of the full-bridge converter, for realizing zero-voltage turn-on of the second switching device and the fourth switching device in a full load range;

A DC blocking capacitor and a saturated inductance, the DC blocking capacitor is connected in series with the primary loop of the transformer of the full bridge converter, and is used to attenuate the current of the primary loop during the circulating current process, and the saturated inductor is connected in series with the DC blocking The capacitor is used to suppress the reversal of the current of the primary loop, and the DC blocking capacitor and the saturated inductance jointly realize zero-current soft switching in the full load range of the second switching device and the fourth switching device.

The control module also includes:

The driving unit is configured to receive the control signal, isolate and amplify the control signal to form a driving signal, and drive the full-bridge converter to work.

The phase-shift control unit for adaptive adjustment of the dead time is a digital circuit;

Generate a phase shift signal corresponding to the dead time of the current signal according to the received current signal, and send the phase shift signal to the driving unit.

The phase-shift control unit for adaptive adjustment of the dead time is an analog circuit;

Including: a phase shift control subunit and a dead time adjustment subunit;

The phase-shift control subunit is used to generate a phase-shift signal for an initial dead time;

The dead time adjustment subunit is configured to receive the current signal, adjust the dead time of the phase shift signal generated by the phase shift control subunit according to the current signal, and adjust the phase shift signal sent to the drive unit.

A phase-shift control method, which is applied to the soft-switching welding inverter power supply according to claim 1, wherein the dead time of the phase-shift signal in the phase-shift control method is adaptively adjusted, and the phase-shift control method includes:

The control module of the soft-switching welding inverter power supply receives the current signal of the full-bridge converter of the soft-switching welding inverter power supply, and adjusts the dead time of the phase-shifting signal according to the current signal.

After the phase shift control method also includes:

The phase-shifted signal after dead-time adjustment is used as a control signal, and is isolated and amplified to form a driving signal to drive the full-bridge converter to work.

A soft switching method, applied to the soft switching welding inverter power supply according to claim 1, the soft switching method is a combination of zero voltage and zero current of the same switching device, specifically comprising:

An auxiliary resonant network is connected in parallel on the bridge arm of the power supply to provide auxiliary energy for the switching device and realize zero-voltage turn-on of the power switching device in a full load range;

Before the switching device of the lagging arm of the soft-switching welding inverter is turned off, the main power loop current flowing through the switching device is attenuated, and the reversal of the main power loop current is suppressed to realize the switching of the lagging arm Zero-current soft switching over the full load range of the device;

A snubber capacitor is connected in parallel with the switching device to slow down the rising speed of the voltage borne by the switching device when it is turned off, so as to realize the zero-voltage turn-off of the switching device in a full load range.

The beneficial effects of the technical solution provided by the embodiments of the present invention are:

By adding a parallel auxiliary resonant network on the super-forearm (leading arm) and lagging arm of the full-bridge converter of the soft-switching welding inverter power supply, it provides additional energy for the zero-voltage soft turn-on of the power switching device, and is supplemented by a transformer The phase-shift control method of adaptively adjusting the dead time when the current (such as the output current of the power supply or the primary current of the transformer) changes, can realize the zero-voltage conduction of the two-arm power switching device in the full load range including no-load and short-circuit states ; By connecting the absorption capacitor in parallel on the power switching device, and connecting the DC blocking capacitor and saturated inductance in series in the primary circuit of the transformer, and cooperating with the zero-voltage and zero-current soft switching method of the same switching device, the approximate zero-voltage turn-off and The soft turn-off of the lagging arm power switch device combined with zero voltage and zero current can effectively solve the problem that the soft turn-on and soft turn-off of the power switch device are difficult to take into account in the full load range, and provide high-efficiency, Lay the foundation for high reliability operation. At the same time, it can be applied to other high-power power supply applications with a wide range of grid input and load variation.

Description of drawings

Fig. 1 is the circuit topology of the basic full-bridge power converter in the prior art;

Fig. 2 is a kind of structural representation of the soft switching welding inverter power source provided in the embodiment 1 of the present invention;

FIG. 3 is a circuit topology of a full-bridge converter using an auxiliary resonant network provided in Embodiment 1 of the present invention;

Fig. 4 is a kind of structural representation of the control module of the soft-switch welding inverter power supply provided in Embodiment 1 of the present invention;

FIG. 5 is a schematic structural diagram of a phase-shift control unit for adaptive adjustment of dead time provided in Embodiment 1 of the present invention;

Fig. 6 is the circuit topology of several equivalent auxiliary resonant networks provided in Embodiment 1 of the present invention;

FIG. 7 is a circuit topology of a full-bridge converter using an auxiliary resonant network provided in Embodiment 2 of the present invention;

Fig. 8 is a schematic diagram of phase-shift control signals for adaptive adjustment of dead time provided in Embodiment 3 of the present invention;

FIG. 9 is a typical working process of the full-bridge soft-switching converter provided in Embodiment 3 of the present invention using the phase-shift control signal adaptively adjusted by the dead time shown in FIG. 8;

Fig. 10 is a schematic diagram of a switching waveform of the lagging arm zero-current soft switch provided in Embodiment 3 of the present invention;

Fig. 11 is a schematic diagram of switching waveforms of the ultra-forearm zero-pressure soft turn-on and zero-pressure soft turn-off provided in Embodiment 3 of the present invention;

Fig. 12 is a typical working process of the full-bridge soft-switching converter provided in Embodiment 4 of the present invention using the phase-shift control signal adaptively adjusted by the dead time shown in Fig. 8;

Fig. 13 is a schematic diagram of switching waveforms of zero-voltage soft turn-on and combined zero-voltage and zero-current soft turn-off of the lagging arm provided in Embodiment 4 of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the implementation manner of the present invention will be further described in detail below in conjunction with the accompanying drawings.

The circuit topology of a basic full-bridge converter is shown in Figure 1. The first switching device Q1 is connected in antiphase parallel with the diode D1, the second switching device Q2 is connected in antiphase parallel with the diode D2, and the third switching device Q3 is connected in antiphase parallel with the diode D3. The fourth switching device Q4 is connected in anti-parallel with the diode D4. The diode can be externally connected to the switching device alone, or can be self-contained inside the switching device. A transformer T is connected between the midpoint of Q1, Q3 and the midpoint of Q2, Q4. The circuit can be controlled by traditional bipolar PWM control technology, or by phase-shift PWM control technology. When adopting the phase-shift PWM control technology, according to the opening and closing of the two bridge arm switching devices, they are respectively called super forearm (leading arm) and lagging arm. In the present invention, it is assumed that Q1, Q3 together with D1 and D3 are super forearm, Q2, Q4 together with D2, D4 are lagging arms.

Example 1

This embodiment provides a soft-switching welding inverter power supply, as shown in FIG. 2 , which includes a full-bridge converter 201 and a control module 202 .

A full-bridge converter 201, configured to work according to the driving signal generated by the control module 202;

The control module 202 is used to receive the current signal of the full-bridge converter 201, and adjust the dead time of the phase-shift signal according to the current signal. The adjusted phase-shift signal is a control signal, and the control signal is isolated and amplified to form a drive signal Drive the full bridge converter 201 to work.

The circuit topology of the full-bridge converter 201 is shown in Figure 3:

The first absorbing capacitor C1 and the third absorbing capacitor C3, C1 is connected in parallel to the first switching device Q1 of the super forearm, and C3 is connected in parallel to the third switching device Q3 of the super forearm, and C1 and C3 are used to jointly realize full switching of Q1 and Q3 Approximate zero-voltage shutdown of the load range;

The super-forearm auxiliary resonant network includes two series-connected auxiliary resonant capacitors Ca1 and Ca3 connected in parallel on the super-forearm, an auxiliary resonant inductor La1 connected to the midpoint of the super-forearm Q1 and Q3 and two series-connected auxiliary resonant capacitors Ca1 and Ca3 The middle point is used to realize the zero-voltage turn-on of the full load range of Q1 and Q3;

The DC blocking capacitor Cb and the saturated inductance Lb, the DC blocking capacitor Cb is connected in series with the primary circuit of the transformer T, and is used to attenuate the current of the primary circuit during the circulation process, and the saturated inductance Lb is connected in series with the DC blocking capacitor Cb, used to suppress the current of the primary circuit Inversely, the DC blocking capacitor Cb and the saturated inductance Lb are used to jointly realize the nearly zero-current soft switching of the full load range of Q2 and Q4.

As shown in FIG. 4 , the control module 202 includes: a phase shift control unit 202A for adaptive adjustment of dead time, and a drive unit 202B.

The phase-shift control unit 202A for adaptive adjustment of the dead time is used to receive the current signal of the full-bridge converter 201, and adjust the dead time of the phase-shift signal according to the current signal, and the adjusted phase-shift signal is a control signal, which is sent to to the drive unit;

The driving unit 202B is used to receive the control signal, isolate and amplify the control signal to form a driving signal, and drive the full-bridge converter 201 to work.

The phase shift control unit 202A for adaptive adjustment of the dead time can be a digital circuit or an analog circuit;

When the phase-shift control unit 202A of the dead-time adaptive adjustment is a digital circuit, according to the received current signal, generate a phase-shift signal corresponding to the dead-time of the current signal, and send the phase-shift signal to the drive unit 202B . The phase-shift control unit 202A of dead-time adaptive adjustment can use DSP (Digital Signal Processor, digital signal processor) or MCU (Microprocessor Control Unit, microprocessor control unit) to realize digital phase-shift control, and realize through software programming Adaptive adjustment of dead time;

When the phase shift control unit 202A of the dead time adaptive adjustment is an analog circuit, referring to FIG. 5 , the phase shift control unit 202A of the dead time adaptive adjustment includes: a phase shift control subunit 202A1 and a dead time adjustment subunit 202A2 ;

The phase-shift control subunit 202A1 is used to generate the phase-shift signal for the initial dead time. This unit can use a dedicated integrated phase-shift control chip, such as UC3875 or UC3879;

The dead-time adjustment subunit 202A2 is used to receive the current signal, adjust the dead-time in a large range to the phase-shift signal generated by the phase-shift control sub-unit 202A1 according to the current signal, and send the adjusted phase-shift signal to the driver as a control signal Unit 202B. The dead time adjustment subunit can be implemented by using a time base circuit 555 or a circuit with similar functions.

The super forearm auxiliary resonant network can adopt various circuit topologies, as shown in Figure 6, the functions of several auxiliary resonant networks are equivalent. Figure 6(a) shows an auxiliary resonant network on the super-forearm, which is a three-terminal network composed of two series-connected auxiliary resonant capacitors and an auxiliary resonant inductor, and the two auxiliary resonant capacitors are connected in parallel on the super-forearm , an auxiliary resonant inductance is connected between the midpoint of the two series auxiliary resonant capacitors connected in parallel on the superforearm and the midpoint of the two switching devices of the superforearm. The auxiliary resonant network in Fig. 6(a) is exactly the auxiliary resonant network used in the circuit topology shown in this embodiment. Figure 6(b) and Figure 6(c) are two-terminal auxiliary resonant network forms that combine two series-connected auxiliary resonant capacitors of the auxiliary resonant network in Figure 6(a), the auxiliary resonant capacitor and the auxiliary resonant Inductors are connected in series to form a double-ended auxiliary resonant network. One end of the double-ended auxiliary resonant network is connected to the midpoint of the two switching devices of the super forearm, and the other end is connected to the positive terminal of the input DC power supply (as shown in Figure 6(b)) Or connect to the negative terminal of the input DC power supply (as shown in Figure 6(c)). Figure 6(d) is based on the three-terminal auxiliary resonant network composed of two series-connected auxiliary resonant capacitors and an auxiliary resonant inductor shown in Figure 6(a), at both ends of the two series-connected auxiliary resonant capacitors Respectively in the form of antiparallel fast recovery diodes, the fast recovery diodes play the role of clamping the voltage of the auxiliary resonant capacitor and providing a freewheeling path for the current of the auxiliary resonant inductor.

In this embodiment, an auxiliary resonant network is connected in parallel on the super-forearm of the full-bridge converter to provide additional energy for the zero-voltage turn-on of the power switching device on the super-forearm, and a parallel absorption capacitor is connected to the power switching device on the super-forearm to realize super-forearm power. For the approximate zero-voltage turn-off of the switching device, the DC blocking capacitor is connected in series on the primary circuit of the transformer to realize the attenuation of the primary circuit current during the circulation process, and the series saturated inductor suppresses the reverse of the primary circuit current, so as to realize the approximate zero current of the lagging arm power switching device shutdown and near zero-current turn-on. According to the transformer current (such as the primary current or the output current of the power supply), the control module adaptively adjusts the dead time of switching between the power switching devices of the leading arm and the lagging arm, and the phase-shifting control signal adaptively adjusted by the dead time is driven by isolation and amplification The power switching device of the full bridge converter controls the opening and closing of the switching device, and realizes the zero-voltage and zero-current soft switching of the soft-switching welding inverter power supply in the full load range including no-load and short-circuit states, in which the super forearm is zero Voltage turn-on and near zero-voltage turn-off, the lagging arm is near zero-current turn-on and near zero-current turn-off, and in the dynamic change process of the power supply load, the soft switching of the power switching device can be maintained. It effectively solves the problem that the soft turn-on and soft turn-off of power switching devices are difficult to balance in the full load range, and lays the foundation for the efficient and reliable operation of the inverter power supply. At the same time, it can be applied to other high-power power supply applications with a wide range of grid input and load variation.

Example 2

This embodiment provides a soft-switching welding inverter power supply, as shown in FIG. 2 , which includes a full-bridge converter 201 and a control module 202 . The circuit topology of the full-bridge converter 201 is shown in Figure 7:

The first absorbing capacitor C1 and the third absorbing capacitor C3, C1 is connected in parallel to the first switching device Q1 of the super forearm, and C3 is connected in parallel to the third switching device Q3 of the super forearm, and C1 and C3 are used to jointly realize full switching of Q1 and Q3 Approximate zero-voltage shutdown of the load range;

The super-forearm auxiliary resonant network includes two series-connected auxiliary resonant capacitors Ca1 and Ca3 connected in parallel on the super-forearm, an auxiliary resonant inductor La1 connected to the midpoint of the super-forearm Q1 and Q3 and two series-connected auxiliary resonant capacitors Ca1 and Ca3 The middle point is used to realize the zero-voltage turn-on of the full load range of Q1 and Q3;

The second absorption capacitor C2 and the fourth absorption capacitor C4, C2 is connected in parallel to the second switching device Q2 of the lagging arm, and C4 is connected in parallel to the fourth switching device Q4 of the lagging arm, and C2 and C4 are used to jointly realize full switching of Q2 and Q4 Approximate zero-voltage shutdown of the load range;

The auxiliary resonant network of the lagging arm includes two series-connected auxiliary resonant capacitors Ca2 and Ca4 connected in parallel on the lagging arm, an auxiliary resonant inductor La2 connected to the midpoint of the lagging arms Q2 and Q4 and two series-connected auxiliary resonant capacitors Ca2 and Ca4 The middle point is used to realize the zero-voltage turn-on of the full load range of Q2 and Q4;

The DC blocking capacitor Cb and the saturated inductance Lb, the DC blocking capacitor Cb is connected in series with the primary circuit of the transformer T, and is used to attenuate the current of the primary circuit during the circulation process, and the saturated inductance Lb is connected in series with the DC blocking capacitor Cb, used to suppress the current of the primary circuit Inversely, the DC blocking capacitor Cb and the saturated inductance Lb are used to jointly realize the approximately zero-current soft switching of the second switching device Q2 and the fourth switching device Q4.

The lagging arm auxiliary resonant network can also adopt various circuit topologies, which are similar to FIG. 6 in Embodiment 1, and will not be described in detail here.

In this embodiment, an auxiliary resonant network is connected in parallel on the super-forearm and the lagging arm of the full-bridge converter to provide additional energy for the zero-voltage turn-on of the power switching devices on the two arms, and parallel connection of absorption capacitors on the power switching devices on the two arms is realized. The approximate zero-voltage turn-off of the two-arm power switching device, the DC blocking capacitor is connected in series on the primary circuit of the transformer to realize the attenuation of the primary circuit current during the circulation process, and the saturated inductor is connected in series on the primary circuit of the transformer to suppress the reverse of the primary circuit current, so as to realize Approximate zero-current turn-off and near-zero-current turn-on of lagging arm power switching devices. According to the transformer current (such as primary current or power supply output current), the control module adaptively adjusts the dead time of the switching of the power switching devices of the leading arm and the lagging arm, and the phase shift control signal adaptively adjusted by the dead time is isolated and amplified to drive the The power switching device of the bridge converter controls the opening and closing of the switching device, and realizes the zero-voltage and zero-current soft switching of the soft-switching welding inverter power supply in the full load range including no-load and short-circuit states, in which the ultra-forearm is zero-voltage Turn-on and near zero-voltage turn-off, the lagging arm is zero-voltage turn-on and soft turn-off combining zero voltage and zero current, and can maintain soft switching of power switching devices during dynamic changes in power supply load. Therefore, it effectively solves the problem that the soft turn-on and soft turn-off of the power switching device are difficult to balance in the full load range, and lays the foundation for the efficient and reliable operation of the inverter power supply. At the same time, it can be applied to other high-power power supply applications with a wide range of grid input and load variation.

Example 3

This embodiment provides a phase-shift control method, which is applied to the soft-switching welding inverter power described in Embodiment 1 and Embodiment 2. Here, the soft-switching welding inverter power supply in Embodiment 1 is taken as an example.

In the full-bridge converter with phase-shift control, the realization of soft switching requires that the dead time of switching devices of the leading arm and the lagging arm be coordinated with the energy in the circuit, and the phase-shift control method of adaptive adjustment of the dead time is It means that the switching dead time of the power switching device of the advanced forearm and the lagging arm decreases with the increase of the transformer current (such as the primary current of the transformer or the output current of the power supply), and the dead time of the advanced forearm has a large adjustment range, while The adjustment range of the dead time of the lagging arm is small, and the lagging arm can even adopt a certain fixed dead time under certain parameter matching.

The control module 202 adjusts the dead time of the phase-shifting signal according to the transformer current (such as the primary current of the transformer or the output current of the power supply) of the full-bridge converter 201, and obtains the phase-shifting control signal adaptively adjusted by the dead time as shown in FIG. 8 :

In the figure, Q1 is the control signal of the first switching device of the super-forearm, Q3 is the control signal of the third switching device of the super-forearm, Q2 is the control signal of the second switching device of the lagging arm, and Q4 is the fourth switch of the lagging arm The control signal of the device, the low level means that the switching device is turned off, and the high level means that the switching device is turned on. The time periods a and b are the dead time of the leading forearm, and the time periods c and d are the dead time of the lagging arm. If the transformer current (such as primary current or power supply output current) in the full-bridge converter 201 increases, the dead time of the two arms shown in FIG. 8 can be correspondingly reduced. Moreover, the adjustment range of the dead time for the switching of the super-forearm switching device is relatively large, while the adjustment range of the dead time for switching of the lagging-arm switching device is relatively small. In some cases, in order to ensure that the corresponding switching device of the advanced forearm is turned on before the corresponding switching device of the lagging arm, such as Q1 is turned on before Q4, or Q3 is turned on before Q2, the phase shift angle of the control pulse can be appropriately limited or effectively Pulse width, effectively control the pulse width as shown in the time periods e and f in Figure 8.

The soft-switching welding inverter power supply in Embodiment 1 adopts the phase-shifting control method of self-adaptive adjustment of the dead-time, and adjusts the dead-zone of the phase-shifting signal according to the transformer current (such as the primary current or the output current of the power supply) of the full-bridge converter 201 time, the adjusted phase-shifting signal is isolated and amplified to form a driving signal to drive the full-bridge converter 201 to work, and the specific working process is shown in Figure 9:

901: The switching devices Q1 and Q4 are in the on state, the primary of the transformer T transfers energy to the secondary, and the auxiliary resonant inductor La1 in the super forearm auxiliary resonant network stores energy. This period of time is determined by the duty cycle.

902: The driving signal turns off Q1, and the current in the primary loop of the transformer and the current in the auxiliary resonant inductor La1 jointly charge the first absorption capacitor C1 and discharge the third absorption capacitor C3. Due to the large capacitance of C1 and C3, the voltage of C1 rises slowly, thus realizing the approximate zero-voltage shutdown of Q1; when the voltage of C1 rises to the power supply voltage and the voltage of C3 drops to zero, D3 turns on, Clamping the voltage of Q3 at zero creates the conditions for Q3 to be turned on with zero voltage.

903: The current in La1 continues to flow through D3, during which the driving signal makes Q3 turn on with zero voltage.

The time from when Q1 is turned off to when Q3 is turned on is the dead time of the super forearm (i.e. the time period b in Fig. 8 ), during which the control module 202 of the soft-switching welding inverter power supply is based on the current of the transformer (such as the primary Loop current or power supply output current) is adaptively adjusted to ensure the zero-voltage turn-on of Q3 in the full load range.

904: The inductor La1 in the auxiliary resonant network resonates with the capacitors Ca1 and Ca3. After the current in La1 decreases to zero, it increases in the opposite direction. The capacitor Ca1 is charged and Ca3 is discharged. The energy storage of the inductor La1 will be for the second half cycle of Q1. Zero-pressure turn-on provides energy conditions.

905: D3 (or Q3) and Q4 are in a conducting state, and the current of the primary circuit of the transformer is in a circulating state until Q4 is turned off.

During the whole circulating current stage, the secondary of the transformer is basically or completely in the state of freewheeling, and the primary and secondary of the transformer are short-circuited, so that the current of the primary circuit of the transformer can drop at a faster speed under the action of the DC blocking capacitor Cb. When the primary circuit of the transformer After the current drops below the saturation current of the saturated inductance Lb, the saturated inductance enters an unsaturated state, thereby inhibiting the current reversal of the primary loop of the transformer.

906: The driving signal turns off Q4, and at this time the current of the primary loop of the transformer is very small or has been reduced to zero, thereby realizing the approximate or complete zero-current shutdown of the lagging arm.

907: Due to the effect of the saturated inductance Lb, the reverse increase of the current of the primary loop of the transformer is suppressed, thereby realizing the nearly zero-current turn-on of Q2.

The time from when Q4 is turned off to when Q2 is turned on is the dead time of the lagging arm (that is, the period d in FIG. 8 ).

908: The switching devices Q3 and Q2 are in the on state, the primary of the transformer transfers energy to the secondary, and the inductor La1 in the auxiliary forearm resonant network stores energy. This period of time is determined by the duty cycle.

909: The circuit starts the working process of the second half cycle, which is completely symmetrical with the working process of the first half cycle.

Using the phase-shift control method of self-adaptive adjustment of the dead time, the lagging arm realizes nearly zero-current turn-on and near-zero-current turn-off in the full load range including no-load and short-circuit states. The typical waveform of the voltage and current on the switching device is as follows: As shown in Figure 10, the abscissa represents time, the ordinate represents the voltage and current on the switching device Q2 (or Q4), the curve V (thin line) represents the voltage waveform on the switching device Q2 (or Q4), and the curve A (thick line ) represents the current waveform on the switching device Q2 (or Q4). For a certain power output current or transformer primary current range, transformer leakage inductance and switching device parasitic capacitance, the circuit topology of the full-bridge converter 201 shown in Embodiment 1 is more reasonable for the soft switching of the lagging arm.

The super forearm realizes the zero-voltage turn-on and near-zero-voltage turn-off of the full load range including no-load and short-circuit conditions. The typical voltage and current waveforms of the super-forearm switching device are shown in Figure 11. The abscissa represents time, and the ordinate represents The voltage and current on the switching device Q1 (or Q3), the curve V (thin line) represents the voltage waveform on the switching device Q1 (or Q3), and the curve A (thick line) represents the current waveform of the switching device Q1 (or Q3). The reverse current is the current on the diode D1 (or D3) connected in antiparallel to the switching device Q1 (or Q3).

In this embodiment, the phase-shifting control method of adaptive adjustment of dead time is applied to the soft-switching welding inverter power supply in embodiment 1, wherein the dead time adjustment range of the advanced forearm is relatively large, and the dead time adjustment range of the lagging arm is large. Smaller, it realizes the zero-voltage turn-on and near-zero-voltage turn-off of the full-load range of the super-forearm including no-load and short-circuit states, and the lagging arm realizes near-zero-current turn-on and near-zero-current turn-off, and is in the power load During the dynamic change process, the soft switching of the power switching device can be maintained, which lays the foundation for the efficient and reliable operation of the inverter power supply. At the same time, the embodiments of the present invention can be applied to other high-power power supply occasions where the grid input and load vary widely.

Example 4

This embodiment provides a soft switching method, which is applied to the soft switching welding inverter power described in Embodiment 2.

The control module 202 adjusts the dead time of the phase-shifting signal according to the transformer current (such as the primary current or the output current of the power supply) of the full-bridge converter 201 to obtain a phase-shifting control signal with adaptive adjustment of the dead time as shown in FIG. 8 .

The soft-switching welding inverter power supply in Example 2, on the basis of the phase-shift control method of self-adaptive adjustment of dead time, applies the soft-switching method, so that the lagging arm realizes the combination of zero voltage and zero current in the full load range soft switch.

According to the transformer current of the full-bridge converter 201 (such as the primary current or the output current of the power supply), the dead time of the phase-shifting signal is adjusted, and the adjusted phase-shifting signal is isolated and amplified to form a driving signal to drive the full-bridge converter 201 to work. , the specific working process is shown in Figure 12:

1201: The switching devices Q1 and Q4 are in the on state, the primary of the transformer T transfers energy to the secondary, and the auxiliary resonant inductors La1 and La2 in the two-arm auxiliary resonant network store energy. This period of time is determined by the duty cycle.

1202: The driving signal turns off Q1, and the current in the primary circuit of the transformer and the current in the auxiliary resonant inductor La1 jointly charge the first absorption capacitor C1 and discharge the third absorption capacitor C3. Due to the large capacitance of C1 and C3, the voltage of C1 rises slowly, thus realizing the approximate zero-voltage shutdown of Q1; when the voltage of C1 rises to the power supply voltage and the voltage of C3 drops to zero, D3 turns on, Clamping the voltage of Q3 at zero creates the conditions for Q3 to be turned on with zero voltage.

1203: The current in La1 continues to flow through D3, during which the driving signal makes Q3 turn on with zero voltage.

The time from when Q1 is turned off to when Q3 is turned on is the dead time of the super forearm (i.e. the time period b in Fig. 8 ), during which the control module 202 of the soft-switching welding inverter power supply is based on the current of the transformer (such as the primary Loop current or power supply output current) is adaptively adjusted to ensure the zero-voltage turn-on of Q3 in the full load range.

1204: The inductor La1 in the auxiliary resonant network resonates with the capacitors Ca1 and Ca3. After the current in La1 decreases to zero, it increases in the opposite direction. The capacitor Ca1 is charged and Ca3 is discharged. The energy storage of the inductor La1 will be for the second half cycle of Q1. Zero-pressure turn-on provides energy conditions.

1205: D3 (or Q3) and Q4 are in a conducting state, and the current of the primary circuit of the transformer is in a circulating state until Q4 is turned off.

During the whole circulating current stage, the secondary circuit of the transformer is basically or completely in the continuous flow state, and the primary and secondary circuits of the transformer are short-circuited, so that the current of the primary circuit of the transformer can drop at a relatively fast speed under the action of the DC blocking capacitor Cb, and the primary circuit of the transformer The current of the loop is attenuated to a large extent, thereby realizing the zero-current turn-off or near-zero-current turn-off of the switching device of the lagging arm.

1206: The drive signal turns off Q4, the primary residual current of the transformer (may have been reversed in some cases) and the current in the auxiliary resonant inductance La2 of the lagging arm jointly charge C4 and discharge C2, because C2 and C4 have a certain Capacitance, which limits the rising speed of the voltage on C4, thereby realizing the approximate zero-voltage soft-off of Q4 on the basis of approximately zero-current soft-off; the current of the primary circuit of the transformer T drops rapidly below the saturation of the saturated inductance Lb current (or less than the saturation current in the circulating current stage), the saturated inductance Lb enters a non-saturation state, so that the current of the auxiliary resonant inductance La2 of the lagging arm will not be lost from the primary circuit of the transformer T too much. When the voltage of C4 rises to the power supply voltage and the voltage of C2 drops to zero, D2 turns on naturally, which clamps the voltage of Q2 to zero, creating a zero-voltage turn-on condition for Q2.

1207: The current in the auxiliary resonant inductance La2 of the lagging arm continues to flow through D2 and continues to drop. Before the current in the auxiliary resonant inductance La2 is not less than the absolute value of the primary reverse current of the transformer T, the driving signal turns on Q2 with zero voltage.

The time from when Q4 is turned off to when Q2 is turned on is the dead time of the lagging arm (see the period d in Figure 8). The dead time of the lagging arm is not sensitive to changes in the transformer current (such as the output current of the power supply). It is necessary to perform dynamic fine-tuning according to the change of the transformer current to ensure the zero-voltage turn-on of Q2 in the full load range; under certain circuit parameter matching, even a certain fixed dead time can be adopted.

1208: The inductor La2 in the lagging arm auxiliary resonant network resonates with the capacitors Ca2 and Ca4, the current in the inductor La2 decreases to zero and then increases in reverse, the capacitor Ca4 is charged, and Ca2 is discharged; the energy storage of the inductor La2 will be Q4 in the second half cycle The zero-pressure turn-on provides energy conditions. The switching devices Q3 and Q2 are in the conduction state, the primary of the transformer transfers energy to the secondary, and the inductors La1 and La2 in the two-arm auxiliary resonant network store energy. This period of time is determined by the duty cycle.

1209: The circuit starts the working process of the second half cycle, which is completely symmetrical with the working process of the first half cycle; it will not be described in detail here.

Utilizing the phase-shift control method of adaptive adjustment of dead time, Super Forearm realizes zero-voltage soft turn-on and near-zero-voltage soft turn-off in the full load range including no-load and short-circuit states. Typical voltage and current waveforms of Super Forearm switching devices As shown in Figure 11, where the abscissa represents time, the ordinate represents the voltage and current on the switching device Q1 (or Q3), the curve V (thin line) represents the voltage waveform on the switching device Q1 (or Q3), and the curve A (thick line) represents the current waveform of the switching device Q1 (or Q3). The reverse current is the current on the diode D1 (or D3) connected in antiparallel to the switching device Q1 (or Q3).

The lagging arm realizes the zero-voltage turn-on of the full load range including no-load and short-circuit conditions, and the soft turn-off of the combination of zero voltage and zero current. The typical voltage and current waveforms of the switching devices of the lagging arm are shown in Figure 13. Among them, The abscissa represents time, the ordinate represents the voltage and current on the switching device Q2 (or Q4), the curve V (thin line) represents the voltage waveform on the switching device Q2 (or Q4), and the curve A (thick line) represents the switching device Q2 (or Q4) on the current waveform. The reverse current is the current on the diode D2 (or D4) connected in antiparallel to the switching device Q2 (or Q4).

In this embodiment, by applying the soft switching method of combining the zero voltage and zero current of the same switching device to the soft switching welding inverter described in Embodiment 2, the super forearm realizes the full load range including no-load and short-circuit Zero-voltage soft turn-on and near-zero-voltage soft turn-off, the lagging arm realizes the combination of zero-voltage soft turn-on and zero-voltage zero-current soft turn-off in the full load range including no-load and short-circuit conditions, and the power supply load During the dynamic change process, the soft switching of the power switching device can be maintained, which lays the foundation for the efficient and reliable operation of the inverter power supply. At the same time, the embodiments of the present invention can be applied to other high-power power supply occasions where the grid input and load vary widely.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (8)

1, a kind of soft switch welding inverter power source is characterized in that, described soft switch welding inverter power source comprises: full-bridge converter and control module;

Described full-bridge converter comprises:

First absorbs electric capacity and the 3rd absorbs electric capacity, described first absorbs on first switching device of leading arm that electric capacity is parallel to described full-bridge converter, the described the 3rd absorbs on the 3rd switching device of leading arm that electric capacity is parallel to described full-bridge converter, described first absorbs electric capacity and the described the 3rd absorbs electric capacity, is used for realizing jointly the zero-pressure shutoff of the full-load range of described first switching device and described the 3rd switching device;

Leading arm auxiliary resonant net is parallel to the leading arm of described full-bridge converter, is used to realize that the zero-pressure of full-load range of described first switching device and described the 3rd switching device is open-minded;

Described control module comprises:

The phase shifting control unit that the Dead Time self adaptation is regulated is used to receive the current signal of described full-bridge converter, and regulates the Dead Time of phase shift signal according to described current signal, with the phase shift signal after regulating as control signal.

2, soft switch welding inverter power source as claimed in claim 1 is characterized in that, described full-bridge transformer also comprises:

Second absorbs electric capacity and the 4th absorbs electric capacity, described second absorbs on the second switch device of lagging leg that electric capacity is parallel to described full-bridge converter, the described the 4th absorbs on the 4th switching device of lagging leg that electric capacity is parallel to described full-bridge converter, described second absorbs electric capacity and the described the 4th absorbs electric capacity, is used for realizing jointly the zero-pressure shutoff of the full-load range of described second switch device and described the 4th switching device;

The lagging leg auxiliary resonant net is parallel to the lagging leg of described full-bridge converter, is used to realize that the zero-pressure of full-load range of described second switch device and described the 4th switching device is open-minded;

Capacitance and pulsactor, described capacitance is series at the primary return of the transformer of described full-bridge converter, be used for electric current at the described primary return of circulation process decay, described pulsactor is series at described capacitance, be used to suppress described primary return electric current oppositely, the common zero-current soft-switch of realizing the full-load range of described second switch device and described the 4th switching device of described capacitance and described pulsactor.

3, soft switch welding inverter power source as claimed in claim 1 is characterized in that described control module also comprises:

Driver element is used to receive described control signal, and described control signal is isolated amplification, forms drive signal, drives described full-bridge converter and carries out work.

4, the soft switch welding inverter power source described in claim 3 is characterized in that, the phase shifting control unit that described Dead Time self adaptation is regulated is a digital circuit;

According to the described current signal that receives, generate phase shift signal, and described phase shift signal is sent to described driver element corresponding to the Dead Time of described current signal.

5, the soft switch welding inverter power source described in claim 3 is characterized in that, the phase shifting control unit that described Dead Time self adaptation is regulated is an analog circuit;

Comprise: phase shifting control subelement and Dead Time are regulated subelement;

Described phase shifting control subelement is used to produce the phase shift signal of initial Dead Time;

Described Dead Time is regulated subelement, is used to receive described current signal, according to described current signal the described phase shift signal that described phase shifting control subelement produces is carried out the adjusting of Dead Time, and the phase shift signal after the adjusting sends to described driver element.

6, a kind of phase-shifting control method is applied to the described soft switch welding inverter power source of claim 1, it is characterized in that, the Dead Time of phase shift signal is that self adaptation is regulated in the described phase-shifting control method, and described phase-shifting control method comprises:

The control module of described soft switch welding inverter power source receives the current signal of the full-bridge converter of described soft switch welding inverter power source, and regulates the Dead Time of phase shift signal according to described current signal.

7, phase-shifting control method as claimed in claim 5 is characterized in that, also comprises after the described phase-shifting control method:

Phase shift signal after Dead Time is regulated amplifies through isolating as control signal, forms drive signal, drives described full-bridge converter and carries out work.

8, a kind of soft-switching process is applied to the described soft switch welding inverter power source of claim 1, it is characterized in that, described soft-switching process is that same switching device Zero-voltage zero-current combines, and specifically comprises:

Auxiliary resonant net in parallel on the brachium pontis of described power supply for described switching device provides auxiliary energy, realizes that the zero-pressure of full-load range of described device for power switching is open-minded;

Before the switching device of the lagging leg of described soft switch welding inverter power source turn-offs, the main loop of power circuit electric current of described switching device is flow through in decay, and suppress the reverse of described main loop of power circuit electric current, realize the zero-current soft-switch of the full-load range of described lagging leg switching device;

The electric capacity that absorbs in parallel on described switching device, the rate of climb of slowing down the voltage that is born when described switching device turn-offs realizes that the zero-pressure of the full-load range of described switching device is turn-offed.

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