A four-switch Buck-Boost forming processing pulse power supply and control method thereof

Abstract

The present invention discloses a four-switch Buck-Boost forming processing pulse power supply and a control method thereof, which is a new forming processing pulse power supply structure proposed based on a four-switch Buck-Boost converter. The circuit combines the gap load characteristics of electrospark machining, and realizes the switching of boost mode and discharge machining mode by detecting and judging the gap voltage. In the boost mode, the high voltage required for gap breakdown can be provided, which can be achieved in two ways. The first way is to achieve boost through the traditional Boost mode; the second way is to achieve boost through zero voltage switch. In the discharge machining mode, the pulse power supply is in Buck mode, and the discharge current is continuously provided to the gap. In the deionization mode, the energy between the gaps is released quickly, and at the same time, the current in the inductor is freewheeling through the switch tube body diode. At the beginning of the next machining cycle, the inductor current will not be 0, which can make the circuit quickly reach a stable state.

Description

Technical Field

[0001] The invention belongs to the field of high-frequency pulse power supply control for forming electrical spark machining, and in particular relates to a four-switch Buck-Boost forming machining pulse power supply and a control method thereof. Background Art

[0002] With the modernization of industry and the development of the times, traditional mechanical processing methods can no longer meet the needs of modern industrial development. At the same time, forming EDM has developed rapidly with its high precision, high efficiency, and high-quality processing, and has great potential in the field of industrial finishing.

[0003] The forming EDM machine tool mainly includes a pulse power supply, a workpiece, a tool electrode, a dielectric and a worktable. EDM technology is a non-contact special processing technology that uses controlled electric energy to form spark discharge between the tool electrode and the workpiece to remove the processed material. Compared with traditional processing, EDM can process special metal materials with high hardness, high strength and high melting point, as well as some precision parts with special structures and complex shapes.

[0004] Pulse power supply is one of the important components of EDM system. During the machining process, the control of discharge current and discharge energy by the system will affect the machining quality and efficiency. Therefore, by proposing a new topology to simplify and improve the overall structure of the circuit, improve energy utilization, and further improve machining efficiency and quality, it has important application value and development prospects. Summary of the invention

[0005] The technical problem to be solved by the present invention is to address the defects of the background technology. The present invention can simplify the circuit structure and reduce the size of the power supply through a four-switch Buck-Boost forming processing pulse power supply and a control method thereof.

[0006] The present invention adopts the following technical solutions to solve the above technical problems:

[0007] A four-switch Buck-Boost forming processing pulse power supply comprises a DC input power supply, a four-switch Buck-Boost pulse power supply main circuit, a drive circuit, a current detection circuit, a voltage detection circuit, and an FPGA controller. The DC input power supply supplies the four-switch Buck-Boost pulse power supply main circuit; the output of the four-switch Buck-Boost pulse power supply main circuit is directly connected to the two ends of a gap load, the voltage detection circuit detects the voltage at the two ends of the gap, the current detection circuit detects the inductor current in the four-switch Buck-Boost pulse power supply main circuit, and the FPGA controller outputs a plurality of PWM signals after calculating the feedback detection values, which are amplified by the drive circuit to drive the switch tubes of the four-switch Buck-Boost pulse power supply main circuit.

[0008] Preferably, the four-switch Buck-Boost pulse power supply main circuit includes an input capacitor C in , the first switch tube Q 1 , the second switch tube Q 2 , the third switch tube Q 3 , the fourth switch tube Q 4 、The fifth switch tube Q 5 , the first body diode D 1 , the second body diode D 2 、The third body diode D 3 、The fourth body diode D 4 、The fifth body diode D 5 , the first junction capacitance C 1 , the second junction capacitance C 2 、The third junction capacitance C 3 , the fourth junction capacitance C 4 、Fifth junction capacitance C 5 , first inductor L, boost output capacitor C f , boost output resistor R f , the first body diode D 1 and the first junction capacitance C 1 The first switch tube Q 1 The parasitic diode and parasitic capacitance of the second body diode D 2 and the second junction capacitance C 2 The second switch tube Q 2 The parasitic diode and parasitic capacitance of the third body diode D 3 and the third junction capacitance C 3 The third switch tube Q 3 The parasitic diode and parasitic capacitance of the fourth body diode D 4 and the fourth junction capacitance C 4 The fourth switch tube Q 4 The parasitic diode and parasitic capacitance of the fifth body diode D5 and the fifth junction capacitance C 5 The fifth switch tube Q 5 The parasitic diode and parasitic capacitance of the input capacitor C in , the first switch tube Q 1 , the second switch tube Q 2 , the third switch tube Q 3 , the fourth switch tube Q 4 、The fifth switch tube Q 5 , the first body diode D 1 , the second body diode D 2 、The third body diode D 3 、The fourth body diode D 4 、The fifth body diode D 5 , the first junction capacitance C 1 , the second junction capacitance C 2 、The third junction capacitance C 3 , the fourth junction capacitance C 4 、Fifth junction capacitance C 5 , first inductor L, boost output capacitor C f , boost output resistor R f The four-switch Buck-Boost pulse power supply main circuit is formed; the first switch tube Q 1 , the second switch tube Q 2 , the third switch tube Q 3 , the fourth switch tube Q 4 The conduction and shutdown control circuit operates in different modes; the fifth switch tube Q 5 Control the on-off of the output load branch in the boost mode. One end of the four-switch Buck-Boost pulse power supply main circuit is connected through the first switch tube Q 1 Connect the positive terminal of the DC input power supply and the input capacitor C in One end of the four-switch Buck-Boost pulse power supply main circuit is connected through the fifth switch tube Q 5 Connect one end of the gap, and the other end of the gap is connected to the negative electrode of the main circuit DC input power supply and the input capacitor C in the other end.

[0009] Preferably, the first switch tube Q 1 , the second switch tube Q 2 , the third switch tube Q 3 , the fourth switch tube Q 4 、The fifth switch tube Q 5 An N-channel enhancement mode metal-oxide semiconductor field effect transistor is used.

[0010] Preferably, the first body diode D 1 , the second body diode D 2、The third body diode D 3 、The fourth body diode D 4 、The fifth body diode D 5 It is the parasitic diode of the switching tube.

[0011] Preferably, the first junction capacitance C 1 , the second junction capacitance C 2 、The third junction capacitance C 3 , the fourth junction capacitance C 4 、Fifth junction capacitance C 5 It is the parasitic capacitance of the switch tube.

[0012] Preferably, the FPGA controller is composed of an FPGA control chip.

[0013] Preferably, the current detection circuit and the voltage detection circuit are implemented by a current Hall sensor and a voltage differential sampling circuit respectively, and are both equipped with a conditioning circuit.

[0014] Preferably, the driving circuit is implemented by a single-channel isolated gate driver.

[0015] A four-switch Buck-Boost forming processing pulse power supply control method, used for the above-mentioned four-switch Buck-Boost forming processing pulse power supply, comprises the following steps:

[0016] Step 1: Before the gap is broken down, that is, in the arc ignition stage, the four-switch Buck-Boost pulse power supply is in the boost mode, and the FPGA controller generates corresponding multi-channel PWM signals, which control the first switch tube Q after passing through the drive circuit. 1 、The fifth switch tube Q 5 Normally open; the second switch tube Q 2 Normally off; the third switch tube Q 3 , the fourth switch tube Q 4 , first inductor L, boost output capacitor C f , boost output resistor R f The Boost circuit is formed to provide high voltage to the gap and wait for the gap to break down;

[0017] Step 2: When the gap breaks down, a discharge channel is formed. During the gap discharge period, the four-switch Buck-Boost pulse power supply is in the discharge machining mode. The FPGA controller generates corresponding multi-channel PWM signals, which control the third switch tube Q after passing through the drive circuit. 3 Normally open; the fourth switch tube Q 4 、The fifth switch tube Q 5 Normally off; the first switch tube Q 1 , the second switch tube Q 2, the first inductor L forms a Buck circuit to continuously provide a discharge current to the gap;

[0018] Step 3: Deionization is required before entering the next discharge cycle. The FPGA controller generates corresponding multi-channel PWM signals, which control the third switch tube Q after passing through the drive circuit. 3 , the fourth switch tube Q 4 On; the first switch tube Q 1 , the second switch tube Q 2 、The fifth switch tube Q 5 Turn off; the voltage across the gap is zero, and the circuit enters the deionization stage, preparing for the next cycle of discharge; the second body diode D 2 , the first inductor L, the fourth switch tube Q 4 A freewheeling loop is formed, and the inductor current will not be 0 at the beginning of the next processing cycle, so that the circuit can quickly reach a stable state;

[0019] Step 4: Repeat steps 1 to 3 to complete the processing cycle.

[0020] Compared with the prior art, the present invention adopts the above technical solution and has the following beneficial effects:

[0021] 1. The four-switch Buck-Boost forming processing pulse power supply and control method thereof provided by the present invention adopts a high-low voltage composite form, simplifies the circuit structure, and reduces the size of the power supply.

[0022] 2. The present invention provides a four-switch Buck-Boost forming processing pulse power supply and a control method thereof, which can provide the high voltage required for gap breakdown in the boost mode, which can be achieved in two ways. The first way is to achieve boost through the traditional Boost mode; the second way is to achieve boost through zero voltage switch.

[0023] 3. The present invention provides a four-switch Buck-Boost forming processing pulse power supply and a control method thereof. In the deionization mode, the energy between the gaps is quickly released, and at the same time, the current in the inductor is freewheeling through the switch tube body diode. At the beginning of the next processing cycle, the inductor current will not be 0, which can enable the circuit to quickly reach a stable state. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 This is a system architecture block diagram of the present invention;

[0026] Figure 2 This is the main circuit topology diagram of the present invention;

[0027] Figure 3 Schematic diagram of gap voltage, inductor current and gap current waveforms of the present invention;

[0028] Figure 4 This is the inductor current detection circuit diagram of the present invention;

[0029] Figure 5 This is a gap voltage detection circuit diagram of the present invention;

[0030] Figure 6 This is the application principle diagram of the driver chip of the present invention. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] A four-switch Buck-Boost forming processing pulse power supply comprises a DC input power supply, a four-switch Buck-Boost pulse power supply main circuit, a drive circuit, a current detection circuit, a voltage detection circuit, and an FPGA controller. The DC input power supply supplies the four-switch Buck-Boost pulse power supply main circuit; the output of the four-switch Buck-Boost pulse power supply main circuit is directly connected to the two ends of a gap load, the voltage detection circuit detects the voltage at the two ends of the gap, the current detection circuit detects the inductor current in the four-switch Buck-Boost pulse power supply main circuit, and the FPGA controller outputs a plurality of PWM signals after calculating the feedback detection values, which are amplified by the drive circuit to drive the switch tubes of the four-switch Buck-Boost pulse power supply main circuit, thereby realizing different working modes and target functions of this pulse power supply.

[0033] As a specific implementation, the four-switch Buck-Boost pulse power supply main circuit includes an input capacitor C in , the first switch tube Q 1 , the second switch tube Q 2 , the third switch tube Q 3 , the fourth switch tube Q 4 、The fifth switch tube Q 5 , the first body diode D 1 , the second body diode D2 、The third body diode D 3 、The fourth body diode D 4 、The fifth body diode D 5 , the first junction capacitance C 1 , the second junction capacitance C 2 、The third junction capacitance C 3 , the fourth junction capacitance C 4 、Fifth junction capacitance C 5 , first inductor L, boost output capacitor C f , boost output resistor R f , the first body diode D 1 and the first junction capacitance C 1 The first switch tube Q 1 The parasitic diode and parasitic capacitance of the second body diode D 2 and the second junction capacitance C 2 The second switch tube Q 2 The parasitic diode and parasitic capacitance of the third body diode D 3 and the third junction capacitance C 3 The third switch tube Q 3 The parasitic diode and parasitic capacitance of the fourth body diode D 4 and the fourth junction capacitance C 4 The fourth switch tube Q 4 The parasitic diode and parasitic capacitance of the fifth body diode D 5 and the fifth junction capacitance C 5 The fifth switch tube Q 5 The parasitic diode and parasitic capacitance of the input capacitor C in , the first switch tube Q 1 , the second switch tube Q 2 , the third switch tube Q 3 , the fourth switch tube Q 4 、The fifth switch tube Q 5 , the first body diode D 1 , the second body diode D 2 、The third body diode D 3 、The fourth body diode D 4 、The fifth body diode D 5 , the first junction capacitance C 1 , the second junction capacitance C 2 、The third junction capacitance C 3 , the fourth junction capacitance C 4 、Fifth junction capacitance C 5 , first inductor L, boost output capacitor C f , boost output resistor R f The four-switch Buck-Boost pulse power supply main circuit is formed; the first switch tube Q1 , the second switch tube Q 2 , the third switch tube Q 3 , the fourth switch tube Q 4 The conduction and shutdown control circuit operates in different modes; the fifth switch tube Q 5 Control the on-off of the output load branch in the boost mode. One end of the four-switch Buck-Boost pulse power supply main circuit is connected through the first switch tube Q 1 Connect the positive terminal of the DC input power supply and the input capacitor C in One end of the four-switch Buck-Boost pulse power supply main circuit is connected through the fifth switch tube Q 5 Connect one end of the gap, and the other end of the gap is connected to the negative electrode of the main circuit DC input power supply and the input capacitor C in the other end.

[0034] As a specific implementation, the first switch tube Q 1 , the second switch tube Q 2 , the third switch tube Q 3 , the fourth switch tube Q 4 、The fifth switch tube Q 5 The present invention adopts an N-channel enhanced metal-oxide semiconductor field effect transistor, and the MOS tube with the model number of IPP60R074C6 produced by Infineon Company can be selected.

[0035] As a specific implementation, the first body diode D 1 , the second body diode D 2 、The third body diode D 3 、The fourth body diode D 4 、The fifth body diode D 5 It is the parasitic diode of the switching tube.

[0036] As a specific implementation manner, the first junction capacitor C 1 , the second junction capacitance C 2 、The third junction capacitance C 3 , the fourth junction capacitance C 4 、Fifth junction capacitance C 5 It is the parasitic capacitance of the switch tube.

[0037] As a specific implementation manner, the FPGA controller is formed by an FPGA control chip, and the present invention can select the chip EP4CE15F23C8 of ALTERA Company.

[0038] As a specific implementation method, the current detection circuit and the voltage detection circuit are respectively implemented by a current Hall sensor and a voltage differential sampling circuit, and are both equipped with a conditioning circuit to ensure the accuracy and integrity of the signal. The current Hall sensor of the present invention uses a current chip of model ACS732, the inductor current is detected and conditioned to obtain a current detection signal, the gap voltage is detected and conditioned by a differential sampling circuit with a resistor divider to obtain a voltage detection signal, and the current and voltage detection signals are converted into digital quantities by an AD9226 module and transmitted to the FPGA controller.

[0039] As a specific implementation, the driving circuit is implemented by a single-channel isolated gate driver, and the invention adopts Infineon's single-channel isolated gate driver 1ED3125MU12F. The driver realizes the isolated driving function through a coreless transformer, and its maximum driving frequency can reach 1MHz, the driving current can reach up to 14A, and the voltage difference of the isolated driving secondary power supply is up to 40V.

[0040] A four-switch Buck-Boost forming processing pulse power supply control method, used for the four-switch Buck-Boost forming processing pulse power supply described above, comprises the following steps:

[0041] Step 1: Before the gap is broken down, that is, in the arc ignition stage, the four-switch Buck-Boost pulse power supply is in the boost mode, and the FPGA controller generates corresponding multi-channel PWM signals, which control the first switch tube Q after passing through the drive circuit. 1 、The fifth switch tube Q 5 Normally open; the second switch tube Q 2 Normally off; the third switch tube Q 3 , the fourth switch tube Q 4 , first inductor L, boost output capacitor C f , boost output resistor R f The Boost circuit is formed to provide high voltage to the gap and wait for the gap to break down;

[0042] Step 2: When the gap breaks down, a discharge channel is formed. During the gap discharge period, the four-switch Buck-Boost pulse power supply is in the discharge machining mode. The FPGA controller generates corresponding multi-channel PWM signals, which control the third switch tube Q after passing through the drive circuit. 3 Normally open; the fourth switch tube Q 4 、The fifth switch tube Q 5 Normally off; the first switch tube Q 1 , the second switch tube Q 2 , the first inductor L forms a Buck circuit to continuously provide a discharge current to the gap;

[0043] Step 3: Deionization is required before entering the next discharge cycle. The FPGA controller generates corresponding multi-channel PWM signals, which control the third switch tube Q after passing through the drive circuit. 3 , the fourth switch tube Q 4 On; the first switch tube Q 1 , the second switch tube Q 2 、The fifth switch tube Q 5 Turn off; the voltage across the gap is zero, and the circuit enters the deionization stage, preparing for the next cycle of discharge; the second body diode D 2 , the first inductor L, the fourth switch tube Q 4 A freewheeling loop is formed, and the inductor current will not be 0 at the beginning of the next processing cycle, so that the circuit can quickly reach a stable state;

[0044] Step 4: Repeat steps 1 to 3 to complete the processing cycle.

[0045] As a specific implementation method, during the EDM process, according to the actual working conditions and processing modes, the multi-channel PWM control signals output by the FPGA controller can drive the corresponding switch tubes to turn on and off after passing through the driving circuit. In view of the gap load characteristics of EDM, in a complete processing cycle, the switching between the boost mode and the discharge processing mode is realized by detecting and judging the gap voltage; after the discharge is completed, the deionization mode is entered, and the inductor current is not zero during the deionization period, so that the circuit can reach a steady state faster in the next processing cycle, and the energy utilization rate is also improved.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A four-switch Buck-Boost pulse power supply for forming processing, It is characterized in that It includes a DC input power supply, a four-switch Buck-Boost pulse power supply main circuit, a drive circuit, a current detection circuit, a voltage detection circuit, and an FPGA controller. The DC input power supply supplies the four-switch Buck-Boost pulse power supply main circuit; The four-switch Buck-Boost pulse power supply main circuit includes an input capacitor C in , the first switch tube Q 1 , the second switch tube Q 2 , the third switch tube Q 3 , the fourth switch tube Q 4 , the fifth switch tube Q 5 , the first body diode D 1 , the second body diode D 2 , the third body diode D 3 , the fourth body diode D 4 , the fifth body diode D 5 , first junction capacitance C 1 , the second junction capacitance C 2 , the third junction capacitance C 3 , the fourth junction capacitance C 4 , Fifth Junction Capacitance C 5 , First Inductor L , boost output capacitor C f , boost output resistor R f , the first body diode D 1 and the first junction capacitance C 1 The first switch Q 1 The parasitic diode and parasitic capacitance of the second body diode D 2 and the second junction capacitance C 2 The second switch Q 2 The parasitic diode and parasitic capacitance of the third body diode D 3 and the third junction capacitance C 3 The third switch Q 3 The parasitic diode and parasitic capacitance of the fourth body diode D 4 and the fourth junction capacitance C 4 The fourth switch Q 4 The parasitic diode and parasitic capacitance of the fifth body diode D 5 and the fifth junction capacitance C 5 The fifth switch Q 5 The parasitic diode and parasitic capacitance of C in , the first switch tube Q 1 , the second switch tube Q 2 , the third switch tube Q 3 , the fourth switch tube Q 4 , the fifth switch tube Q 5 , the first body diode D 1 , the second body diode D 2 , the third body diode D 3 , the fourth body diode D 4 , the fifth body diode D 5 , first junction capacitance C 1 , the second junction capacitance C 2 , the third junction capacitance C 3 , the fourth junction capacitance C 4 , Fifth Junction Capacitance C 5 , First Inductor L , boost output capacitor C f , boost output resistor R f The four-switch Buck-Boost pulse power supply main circuit is formed; the first switch tube Q 1 , the second switch tube Q 2 , the third switch tube Q 3 , the fourth switch tube Q 4 The conduction and shutdown control circuit operates in different modes; the fifth switch tube Q 5 Control the on-off of the output load branch in the boost mode, one end of the four-switch Buck-Boost pulse power supply main circuit is connected through the first switch tube Q 1 Connect the positive terminal of the DC input power supply and the input capacitor C in One end of the four-switch Buck-Boost pulse power supply main circuit is connected through the fifth switch tube Q 5 Connect one end of the gap, and the other end of the gap is connected to the negative pole of the main circuit DC input power supply and the input capacitor C in The other end of the four-switch Buck-Boost pulse power supply main circuit output is directly connected to the two ends of the gap load, the voltage detection circuit detects the voltage at both ends of the gap, and the current detection circuit detects the inductor current in the four-switch Buck-Boost pulse power supply main circuit. The FPGA controller calculates the feedback detection value and outputs a multi-channel PWM signal, which is amplified by the drive circuit to drive the switch tube of the four-switch Buck-Boost pulse power supply main circuit.

2. The four-switch Buck-Boost forming processing pulse power supply according to claim 1, It is characterized in that The first switch tube Q 1 , the second switch tube Q 2 , the third switch tube Q 3 , the fourth switch tube Q 4 , the fifth switch tube Q 5 An N-channel enhancement mode metal-oxide semiconductor field effect transistor is used.

3. The four-switch Buck-Boost forming processing pulse power supply according to claim 1, It is characterized in that The first body diode D 1 , the second body diode D 2 , the third body diode D 3 , the fourth body diode D 4 , the fifth body diode D 5 It is the parasitic diode of the switching tube.

4. The four-switch Buck-Boost forming processing pulse power supply according to claim 1, It is characterized in that The first junction capacitance C 1 , the second junction capacitance C 2 , the third junction capacitance C 3 , the fourth junction capacitance C 4 , Fifth Junction Capacitance C 5 It is the parasitic capacitance of the switch tube.

5. The four-switch Buck-Boost forming processing pulse power supply according to claim 1, It is characterized in that The FPGA controller is composed of an FPGA control chip.

6. The four-switch Buck-Boost forming processing pulse power supply according to claim 1, It is characterized in that The current detection circuit and the voltage detection circuit are respectively implemented by a current Hall sensor and a voltage differential sampling circuit, and are both equipped with a conditioning circuit.

7. The four-switch Buck-Boost forming processing pulse power supply according to claim 1, It is characterized in that The driving circuit is implemented by a single-channel isolated gate driver.

8. A four-switch Buck-Boost forming processing pulse power supply control method, used for a four-switch Buck-Boost forming processing pulse power supply as described in any one of claims 1 to 7 above, It is characterized in that The steps include: Step 1: Before the gap is broken down, that is, in the arc ignition stage, the four-switch Buck-Boost pulse power supply is in the boost mode, and the FPGA controller generates corresponding multi-channel PWM signals, which control the first switch tube after passing through the drive circuit. Q 1 , the fifth switch tube Q 5 Normally open; second switch tube Q 2 Normally closed; the third switch Q 3 , the fourth switch tube Q 4 , First Inductor L , boost output capacitor C f , boost output resistor R f The Boost circuit is formed to provide high voltage to the gap and wait for the gap to break down; Step 2: When the gap breaks down, a discharge channel is formed. During the gap discharge period, the four-switch Buck-Boost pulse power supply is in the discharge machining mode. The FPGA controller generates corresponding multi-channel PWM signals, which control the third switch tube after passing through the drive circuit. Q 3 Normally open; the fourth switch Q 4 , the fifth switch tube Q 5 Normally closed; the first switch Q 1 , the second switch tube Q 2 , First Inductor L A Buck circuit is formed to continuously provide discharge current to the gap; Step 3: Deionization is required before entering the next discharge cycle. The FPGA controller generates corresponding multi-channel PWM signals, which control the third switch tube after passing through the drive circuit. Q 3 , the fourth switch tube Q 4 The first switch is turned on. Q 1 , the second switch tube Q 2 , the fifth switch tube Q 5 Turn off; the voltage across the gap is zero, and the circuit enters the deionization stage, preparing for the next cycle of discharge; the second body diode D 2 , First Inductor L , the fourth switch tube Q 4 A freewheeling loop is formed, and the inductor current will not be 0 at the beginning of the next processing cycle, so that the circuit can quickly reach a stable state; Step 4: Repeat steps 1 to 3 to complete the processing cycle.

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