阅读说明：本技术 分组式微细电火花加工脉冲电源 (Grouping type micro electric spark machining pulse power supply ) 是由 杨飞 张开翔 陈希岩 张建超 李玉坤 王新鹏 李磊 于 2021-09-28 设计创作，主要内容包括：本发明公开了一种分组式微细电火花加工脉冲电源,在传统RC式脉冲电源的基础上,该电源采用反激电路向多组储能电容进行同步充电,通过使用FPGA控制副边侧开关管与继电器的通断实现不同放电回路的选通,配合调整原边侧开关管的导通时长能够提供多个等级的能量输出。本发明有效解决传统RC式脉冲电源充电时间长、电阻耗能大、放电能量不可控的问题,在提高微细电火花加工效率的同时兼顾加工质量与精度要求。(The invention discloses a grouped micro electric spark machining pulse power supply, which adopts a flyback circuit to synchronously charge a plurality of groups of energy storage capacitors on the basis of the traditional RC type pulse power supply, realizes gating of different discharge loops by controlling the on-off of a secondary side switch tube and a relay by using an FPGA (field programmable gate array), and can provide energy output of multiple levels by matching with adjustment of the on-off duration of a primary side switch tube. The invention effectively solves the problems of long charging time, large resistance energy consumption and uncontrollable discharge energy of the traditional RC type pulse power supply, improves the micro electric spark machining efficiency and simultaneously considers the requirements of machining quality and precision.)

1. A grouped micro electric spark machining pulse power supply is characterized by comprising a direct current source, a pulse power supply main circuit, a sampling circuit, an FPGA controller and a driving circuit; the pulse power supply main circuit outputs energy for the gap, the sampling circuit samples voltage and gap current at two ends of the gap respectively, sampling signals are input to the FPGA control module, control signals are generated according to processing requirements, the control signals drive each switch tube and each relay in the pulse power supply main circuit through the driving circuit respectively, and finally charging and discharging of each energy storage capacitor are controlled, so that multiple energy-accurate and controllable grouped pulses continuously generated in a discharging gap are subjected to micro-processing.

2. The grouped micro electro-discharge machining (EDM) pulse power supply of claim 1, wherein the circuit includes an input capacitor (C)_inA clamp circuit capacitor C_σA clamp circuit resistor R_σClamping circuit diode D_σA primary side switch tube Q and a primary side inductor L_pTransformer T, secondary side inductor L_sA main diode D at the secondary side and a dummy load resistor R, a, and each energy storage capacitor C_1a～C_naB groups of energy storage capacitors C_1b～C_nbEnergy storage capacitor gating relay J₁～J_nAnd each path of discharge switch tube Q₁～Q_nEach charging diode D_1i～D_niEach path of discharge diode D_1o～D_no(ii) a Wherein, the primary side inductance L_pOne end of the primary side switch tube is connected with the Q drain electrode of the primary side switch tube, the source electrode of the primary side switch tube and the input capacitorC_inThe cathode is connected with a DC source V_inThe cathode is connected, and the anode of the input capacitor and the other end of the primary side inductor are connected with the anode of the direct current source together; clamp circuit resistor R_σAnd clamp circuit capacitor C_σParallel connection, one end connected with anode of DC source and the other end connected with diode D of clamping circuit_σCathode, clamping circuit diode D_σThe anode of the switch tube is connected to the drain electrode of the primary side switch tube to form an RCD clamping circuit; secondary side inductor L_sThrough the transformer T and the primary side inductance L_pCoupling, wherein the anode of a primary diode D at the secondary side is connected with one end of a primary inductor at the secondary side, the cathode of the primary diode at the secondary side is a flyback output anode, the other end of the primary inductor at the secondary side is a flyback output cathode, and two ends of a dummy load resistor R are respectively connected with the flyback output anode and the flyback output cathode; n loops with the same structure are arranged between the positive pole and the negative pole of the flyback output, wherein the kth loop is formed by a charging diode D_kiDischarge diode D_koDischarge switching tube Q_kEnergy storage capacitor gating relay J_kAnd an energy storage capacitor C_kaAnd C_kbComposition, charging diode D_kiA discharge diode D with an anode connected with the positive electrode of the flyback output_koThe anode is connected with the cathode of the charging diode, and the discharging switch tube Q_kThe drain electrode is connected with the cathode of the discharge diode, and the energy storage capacitor gates the relay J_kOne end of the capacitor is connected with the anode of the discharge diode, and the other end of the capacitor is connected with the energy storage capacitor C_kaAnd C_kaThe anode of the energy storage capacitor is connected with the flyback output cathode; the source electrode of the discharge switch tube is a discharge gap anode, and the flyback output cathode is a discharge gap cathode.

3. The grouped type micro electric discharge machining pulse power supply according to claim 2, wherein the circuit includes a primary side switch tube Q and each path of discharge switch tubes Q₁～Q_nA metal-oxide semiconductor field effect transistor (MOSFET) is adopted, and the material of the MOSFET is Si, SiC or GaN; clamping circuit diode D_σA secondary side main diode D and charging diodes D_1i～D_niEach path of discharge diode D_1o～D_noUsing schottkyA diode; input capacitance C_inA groups of energy storage capacitors C_1a～C_naB groups of energy storage capacitors C_1b～C_nbAn aluminum electrolytic capacitor with polarity is adopted; primary side inductor L_pSecondary side inductor L_sThe transformer T core is made of manganese-zinc-ferrite and is made of PC 44.

4. The grouped type micro electric discharge machining pulse power supply according to claim 2, wherein the Q is switched by controlling each path of discharge switch tube₁～Q_nThe control of the discharge time of each path of capacitor in micro machining is realized, so that continuous grouping pulses with accurately controllable energy are generated in the micro machining, the micro electric discharge machining efficiency is improved, and the machining quality and the precision requirement are considered.

5. The grouped type micro electric discharge machining pulse power supply according to claim 2, wherein the relay J is gated by controlling each energy storage capacitor₁～J_nEach path of capacitance participating in discharging is selected, and then the grouped pulse energy during discharging is accurately adjusted according to the machining requirement and the actual working condition, so that the use condition and the range of the grouped micro electric discharge machining pulse power supply are wider.

6. The grouped micro electric discharge machining pulse power supply according to claim 1, wherein the current sampling and voltage sampling circuit uses a 12-bit analog-to-digital conversion chip AD9226, a high-performance sample-hold amplifier and a reference voltage source are arranged in the current sampling and voltage sampling circuit, a multi-stage differential pipeline architecture is adopted, sampling values are transmitted in parallel, the maximum data transmission rate can reach 65MSPS, and no missing codes are ensured in the whole working temperature range.

7. The grouped micro electric discharge machining pulse power supply according to claim 1, wherein the control circuit adopts an FPGA as a main control chip, utilizes the characteristic that the logic control of the FPGA chip can be freely programmed, fully exerts the characteristics of abundant IO interface resources, high working frequency, high speed and the like of the FPGA chip, realizes real-time control of charging and discharging of a plurality of loops, and finally realizes accurate control of energy of each grouped pulse during micro machining.

8. The grouped type micro electro discharge machining pulse power supply according to claim 1, wherein a driving circuit composed of a gate driving chip having an isolated high-side and low-side dual-channel output is selected to drive each switching tube in the main circuit, and a driving circuit composed of an NPN type triode is used to drive each relay in the main circuit.

9. The control and operating principle of a power supply according to any one of claims 1 to 8, characterized by comprising the steps of:

the method comprises the following steps: before processing, according to the processing requirement and the actual working condition, the FPGA generates a relay control signal, and each path of energy storage capacitor is driven by a driving circuit to gate the relay J₁～J_nSelecting each path of capacitor group participating in work, and selecting the capacitance value of each path of working capacitor;

step two: the FPGA controller generates a control signal, the primary side switch tube Q is switched on through the driving circuit, and the direct current source V is connected with the primary side switch tube Q_inIs a primary side inductor L_pCharging, primary side inductance L_pEnergy storage is started, the main diode D on the secondary side is in an off state at the moment, and no current passes through the secondary side;

step three: when the energy storage time reaches a preset value, the FPGA controller generates a control signal, the primary side switch tube Q is turned off through the driving circuit, the secondary side main diode D is in an on state at the moment, and the magnetic field energy in the transformer T passes through the secondary side inductor L_sAnd a secondary side main diode D, and charging diodes D_1i～D_niCharging each working capacitor;

step four: when the charging time of the capacitor reaches a preset value, the FPGA controller generates various control signals to drive various discharging switch tubes Q₁～Q_nSequentially conducting and stopping to make each working capacitor pass through each discharge diode D_1o～D_noAnd each path of discharge switch tube Q₁～Q_nSequentially discharging to the gap, continuously generating a plurality of grouped pulses in the discharge gap for micro-machining, and entering the next machining cycle after the discharge of all capacitors is finished;

step five: or on the occasion that the required machining energy is large, the FPGA controller can also generate control signals to drive the plurality of discharge switch tubes to be switched on and switched off simultaneously, so that the plurality of capacitors are used as a group to discharge to the gaps simultaneously, then the plurality of groups of capacitors are controlled to discharge to the gaps sequentially, and the next machining period is entered until all the capacitors finish discharging, and the electric spark machining is carried out by continuously generating a plurality of grouped pulses with large energy in the discharge gaps;

step six: and repeating the second step to the fifth step to realize the circulation of the processing period.

10. The grouped type micro electric discharge machining pulse power supply according to claim 1, wherein when electric discharge machining is performed, the FPGA controller generates control signals to drive the primary side switch tube Q and each path of discharge switch tube Q according to machining requirements and actual working conditions₁～Q_nOn and off, and simultaneously drives each energy storage capacitor to gate the relay J₁～J_nAnd selecting the capacitance value of each working capacitor, thereby realizing the micro-machining of a plurality of grouped pulses with accurately controllable energy continuously generated in the discharge gap.

Technical Field

The invention relates to the field of pulse power supplies for electric spark machining, in particular to a grouped micro electric spark machining pulse power supply.

Background

With the development of the machining industry in recent years in China, the market demand of the machining industry puts higher requirements on the size, the precision, the machining efficiency and the like of micro machining. As a novel non-contact machining and manufacturing method, micro electric discharge machining is suitable for special machining occasions such as special parts with complex shapes and difficult-to-cut materials, has the advantages of low stress, no burrs, capability of machining high-hardness materials and the like, and is widely applied to machining of micro shaft holes, cavities and the like.

With the development of micro electric discharge machining, the machining industry pays more attention to machining precision, quality and machining efficiency under the condition of meeting the basic application occasions. First, the size of the discharge pit is an important factor for determining the precision and quality of micro-electrical discharge machining, and in order to make the discharge pit generated during machining smaller, it is necessary to minimize the discharge energy of a single pulse, which is generally 10, while ensuring that an electrical discharge pulse power supply can generate an electrical discharge^-7～10^-6Generally, the main methods for reducing the discharge energy of a single pulse are to reduce the discharge voltage and the pulse width, but since a certain maintaining voltage needs to exist in the gap during the electric spark machining, reducing the pulse width is the most important technical means for improving the machining precision and quality at present on the basis of ensuring the discharge voltage. In addition, since pulse energy is small in micro machining, machining efficiency is generally low compared to high-power electric discharge machining.

At present, an RC type pulse power supply is commonly used for micro electric spark machining, and the power supply is simple in structure, easy to adjust single-pulse discharge energy and high in charge and discharge frequency. However, when the RC type pulse power supply is used for micro-machining, the charging time is long, the energy loss is large, the pulse parameters are unstable, the machining efficiency is low, and the like, and the requirements of industrial application cannot be met. Therefore, a novel circuit topology is generated by continuously improving the traditional RC type pulse power supply, the machining efficiency of the fine electric spark machining pulse power supply is further improved while the machining precision and quality are improved, and the method has important research and application values.

Disclosure of Invention

The invention aims to solve the technical problem of the background technology, and provides a grouped micro electric spark machining pulse power supply which has the advantages of improving the micro electric spark machining efficiency and simultaneously considering the machining quality and precision requirements compared with the traditional RC type pulse power supply.

The invention adopts the following technical scheme for solving the technical problems:

a grouped micro electric spark machining pulse power supply comprises a direct current source, a pulse power supply main circuit, a gap voltage and current sampling circuit, an FPGA controller and a driving circuit; the pulse power supply main circuit outputs energy for a gap, the sampling circuit samples voltage and gap current at two ends of the gap respectively, sampling signals are input to the FPGA control module, control signals are generated according to processing requirements, and the control signals are generated through the driving circuit to drive a primary side switch tube Q and each path of discharge switch tube Q of the pulse power supply main circuit respectively₁～Q_nEnergy storage capacitor gating relay J₁～J_nFinally controlling each energy storage capacitor C_1a～C_naAnd C_1b～C_nbAnd charging and discharging so as to realize the fine machining of a plurality of grouped pulses with accurately controllable energy continuously generated in the discharge gap.

Based on the grouped micro electric spark machining pulse power supply, the characteristic and the working process thereof comprise the following steps:

the method comprises the following steps: before processing, according to the processing requirement and the actual working condition, the FPGA generates a relay control signal, and each path of energy storage capacitor is driven by a driving circuit to gate the relay J₁～J_nAnd selecting each path of capacitor group participating in work, and selecting the capacitance value of each path of working capacitor.

Step two: the FPGA controller generates a control signal, the primary side switch tube Q is switched on through the driving circuit, and the direct current source V is connected with the primary side switch tube Q_inIs a primary side inductor L_pCharging, primary side inductance L_pAnd (4) energy storage is started, the main diode D on the secondary side is in an off state at the moment, and no current passes through the secondary side.

Step three: when the energy storage time reaches a preset value, the FPGA controller generates a control signal, the primary side switch tube Q is turned off through the driving circuit, the secondary side main diode D is in an on state at the moment, and the transformer T is used for converting the energy storage time into a voltageEnergy of magnetic field passing through secondary side inductor L_sAnd a secondary side main diode D, and charging diodes D_1i～D_niAnd charging the working capacitors.

Step four: when the charging time of the capacitor reaches a preset value, the FPGA controller generates various control signals to drive various discharging switch tubes Q₁～Q_nSequentially conducting and stopping to make each working capacitor pass through each discharge diode D_1o～D_noAnd each path of discharge switch tube Q₁～Q_nSequentially discharging to the gap, continuously generating a plurality of grouped pulses in the discharge gap for micro-machining, and entering the next machining cycle after the discharge of all capacitors is finished.

Step five: or on the occasion that the required machining energy is large, the FPGA controller can also generate control signals to drive the plurality of discharge switch tubes to be switched on and switched off simultaneously, so that the plurality of capacitors are used as a group to discharge to the gaps simultaneously, then the plurality of groups of capacitors are controlled to discharge to the gaps sequentially, and the next machining period is entered until the discharge of all the capacitors is finished, and the electric spark machining is carried out by continuously generating a plurality of grouped pulses with large energy in the discharge gaps.

Step six: and repeating the second step to the fifth step to realize the circulation of the processing period.

Compared with the prior art, the invention adopting the technical scheme has the following technical effects:

1. the grouped discharge circuits are distributed in parallel, the discharge circuits are good in independence, the voltage of each grouped energy storage capacitor is high in consistency with the grouped discharge current, and the discharge energy is accurate and controllable;

2. the energy storage capacitors and the multiple groups of energy storage capacitors can be gated through the relay to discharge in a combined manner according to the machining requirements and the actual working conditions, so that multiple energy levels are provided;

3. by controlling the input voltage of the direct current source and the duty ratio of the switching tube on the primary side, the output voltage is flexible and adjustable, and the open-circuit voltage suitable for processing can be provided for the gap;

4. the input and output of the converter are electrically isolated, the influence of the switching action of the primary side switching tube on the discharge gap is effectively avoided, and the processing stability is improved.

Drawings

FIG. 1 is a system diagram of a grouped micro electro discharge machining pulse power supply according to the present invention.

Fig. 2 is a topology diagram of the main circuit of the pulse power supply of the present invention.

Fig. 3 is a schematic diagram of a processing waveform of a grouped micro electric discharge machining pulse power supply according to the present invention.

Fig. 4 is a schematic diagram of an application of an analog-to-digital conversion chip used in the sampling circuit of the present invention.

Fig. 5 is a schematic diagram of an application of a dual-end isolated gate driver chip used in the driving circuit of the present invention.

Detailed Description

The invention is described in further detail below with reference to the accompanying drawings.

The present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

As shown in FIG. 1, the grouped micro electric spark machining pulse power supply of the invention comprises a direct current source, a pulse power supply main circuit, a gap voltage and current sampling circuit, an FPGA controller and a driving circuit; the pulse power supply main circuit outputs energy for a gap, the sampling circuit samples voltage and gap current at two ends of the gap respectively, sampling signals are input to the FPGA control module, control signals are generated according to processing requirements, and the control signals are generated through the driving circuit to drive a primary side switch tube Q and each path of discharge switch tube Q of the pulse power supply main circuit respectively₁～Q_nEnergy storage capacitor gating relay J₁～J_nFinally controlling each energy storage capacitor C_1a～C_naAnd C_1b～C_nbAnd charging and discharging so as to realize the fine machining of a plurality of grouped pulses with accurately controllable energy continuously generated in the discharge gap.

As shown in FIG. 2, the main circuit of the pulse power supply comprises an input capacitor C_inA clamp circuit capacitor C_σA clamp circuit resistor R_σClamping circuit diodeD_σA primary side switch tube Q and a primary side inductor L_pTransformer T, secondary side inductor L_sA main diode D at the secondary side and a dummy load resistor R, a, and each energy storage capacitor C_1a～C_naB groups of energy storage capacitors C_1b～C_nbEnergy storage capacitor gating relay J₁～J_nAnd each path of discharge switch tube Q₁～Q_nEach charging diode D_1i～D_niEach path of discharge diode D_1o～D_no. Wherein, the primary side inductance L_pOne end of the primary side switch tube is connected with the drain electrode of the Q switch tube, the source electrode of the primary side switch tube and the input capacitor C_inThe cathode is connected with a DC source V_inThe cathode is connected, and the anode of the input capacitor and the other end of the primary side inductor are connected with the anode of the direct current source together; clamp circuit resistor R_σAnd clamp circuit capacitor C_σParallel connection, one end connected with anode of DC source and the other end connected with diode D of clamping circuit_σCathode, clamping circuit diode D_σThe anode of the switch tube is connected to the drain electrode of the primary side switch tube to form an RCD clamping circuit; secondary side inductor L_sThrough the transformer T and the primary side inductance L_pCoupling, wherein the anode of a primary diode D at the secondary side is connected with one end of a primary inductor at the secondary side, the cathode of the primary diode at the secondary side is a flyback output anode, the other end of the primary inductor at the secondary side is a flyback output cathode, and two ends of a dummy load resistor R are respectively connected with the flyback output anode and the flyback output cathode; n loops are arranged between the positive electrode and the negative electrode of the flyback output, the loops have the same structure, wherein the kth loop is formed by a charging diode D_kiDischarge diode D_koDischarge switching tube Q_kEnergy storage capacitor gating relay J_kAnd an energy storage capacitor C_kaAnd C_kbComposition, charging diode D_kiA discharge diode D with an anode connected with the positive electrode of the flyback output_koThe anode is connected with the cathode of the charging diode, and the discharging switch tube Q_kThe drain electrode is connected with the cathode of the discharge diode, and the energy storage capacitor gates the relay J_kOne end of the capacitor is connected with the anode of the discharge diode, and the other end of the capacitor is connected with the energy storage capacitor C_kaAnd C_kaThe anode of the energy storage capacitor is connected with the flyback output cathode; putThe source electrode of the electric switch tube is a discharge gap anode, and the flyback output cathode is a discharge gap cathode.

The primary side switch tube and each discharge switch tube in the pulse power supply main circuit adopt silicon-based metal-oxide semiconductor field effect transistors (MOSFET), and a novel wide bandgap device made of Si, SiC or GaN and other materials can be selected to further improve the overall performance of the circuit; the invention selects an N-channel MOSFET with the model number of IPP220N25NFD of Infineon company, the rated voltage of the MOSFET is 250V, the rated current of the MOSFET is as high as 61A, and the MOSFET can completely meet various working condition requirements in processing. Because the whole circuit works in a high-frequency state, Schottky diodes with higher working frequency must be used for the clamping circuit diodes, the secondary side main diodes, all the charging diodes and all the discharging diodes; the Schottky diode of the type MBR40250TG of ON (Anson America) is selected, the conduction forward voltage drop is 0.86V, the rated forward average current is 40A, the reverse withstand voltage value is 250V, and the performance parameters meet the power supply requirement. The manganese-zinc ferrite magnetic core with high working frequency is selected as the T magnetic core of the transformer consisting of the primary side inductor and the secondary side inductor, the magnetic core with the model of PC44 of TDK company is selected, the magnetic conductivity of the magnetic core is higher, the number of turns of the inductor in the transformer can be less, and the volume of the transformer can be smaller.

The sampling circuit needs to sample the voltage and current between the discharge gaps in real time so as to realize the closed-loop control of the grouped micro electric spark machining pulse power supply, and the control strategy is adjusted in real time according to the gap discharge state, so that the sampling circuit is built by utilizing a 12-bit analog-to-digital conversion chip to input the sampled voltage and current data to the FPGA; according to the invention, a chip with the model number of AD9226 of ADI company is selected to build a sampling circuit, as shown in figure 4, a high-performance sample-hold amplifier and a reference voltage source are arranged in the sampling circuit, a multi-stage differential pipeline architecture is adopted, sampling values are transmitted in parallel, the highest data transmission rate can reach 65MSPS, and no missing code is ensured in the whole working temperature range.

The circuit of the invention adopts FPGA as a main control chip, utilizes the characteristic that the logic control of the FPGA chip can be freely programmed, fully exerts the characteristics of abundant IO interface resources, high working frequency, high speed and the like of the FPGA chip, realizes the real-time control of the charging and discharging of a plurality of loops, and finally realizes the accurate control of the energy of each grouped pulse during the micro-machining.

The driving circuit is composed of a switch tube drive and a relay drive. For the switching tube driving circuit, the invention adopts a high-low end driving chip with isolation to build each switching tube driving circuit in a main circuit, as an example, a grid driving chip with a model of UCC21521 of TI (Texas instruments) company, as shown in FIG. 5, the chip has a 4A peak value source current and a 6A peak value sink current, the maximum driving frequency is 5MHz, and the chip has a first-class propagation delay and pulse width distortion degree; the input side is isolated from the two output drivers through a 5.7kVRMS enhanced isolation gate, and the minimum value of Common Mode Transient Immunity (CMTI) is 100V/ns; the two secondary side drivers are isolated by adopting internal functions and support the working voltage of up to 1500V of direct current; when the primary side logic fails, the two outputs are forced to be low level for safety protection; all power supply voltage pins have an under-voltage lockout (UVLO) protection function; the chip can improve the power efficiency and stability integrally. Meanwhile, the relay drive adopts a drive circuit composed of NPN type triodes to amplify the control signal of the FPGA and drive each relay in the main circuit; the model of UMW (friend table semiconductor) company is S8050, and compared with a common NPN type triode, the model of the triode has higher working high frequency and is suitable for a high-frequency working state.

In summary, the grouping type micro electric discharge machining pulse power supply provided by the invention generates the control signals to drive the primary side switch tube Q and each path of discharge switch tube Q according to the micro electric discharge machining requirements and the actual working conditions during electric discharge machining according to the machining requirements and the actual working conditions₁～Q_nOn and off, and simultaneously drives each energy storage capacitor to gate the relay J₁～J_nAnd selecting the capacitance value of each working capacitor, thereby realizing that a plurality of grouped pulses with accurately controllable energy continuously generated in the discharge gap are subjected to micro-machining, improving the micro-electrical discharge machining efficiency and simultaneously considering the machining quality and precision requirements.

The working waveform during processing is shown in fig. 3, and the specific process is as follows:

the method comprises the following steps: before processing, according to the processing requirement and the actual working condition, the FPGA generates a relay control signal, and each path of energy storage capacitor is driven by a driving circuit to gate the relay J₁～J_nAnd selecting each path of capacitor group participating in work, and selecting the capacitance value of each path of working capacitor.

Step two: the FPGA controller generates a control signal, the primary side switch tube Q is switched on through the driving circuit, and the direct current source V is connected with the primary side switch tube Q_inIs a primary side inductor L_pCharging, primary side inductance L_pAnd (4) energy storage is started, the main diode D on the secondary side is in an off state at the moment, and no current passes through the secondary side.

Step three: when the energy storage time reaches a preset value, the FPGA controller generates a control signal, the primary side switch tube Q is turned off through the driving circuit, the secondary side main diode D is in an on state at the moment, and the magnetic field energy in the transformer T passes through the secondary side inductor L_sAnd a secondary side main diode D, and charging diodes D_1i～D_niAnd charging the working capacitors.

Step four: when the charging time of the capacitor reaches a preset value, the FPGA controller generates various control signals to drive various discharging switch tubes Q₁～Q_nSequentially conducting and stopping to make each working capacitor pass through each discharge diode D_1o～D_noAnd each path of discharge switch tube Q₁～Q_nSequentially discharging to the gap, continuously generating a plurality of grouped pulses in the discharge gap for micro-machining, and entering the next machining cycle after the discharge of all capacitors is finished.

Step five: or on the occasion that the required machining energy is large, the FPGA controller can also generate control signals to drive the plurality of discharge switch tubes to be switched on and switched off simultaneously, so that the plurality of capacitors are used as a group to discharge to the gaps simultaneously, then the plurality of groups of capacitors are controlled to discharge to the gaps sequentially, and the next machining period is entered until the discharge of all the capacitors is finished, and the electric spark machining is carried out by continuously generating a plurality of grouped pulses with large energy in the discharge gaps.

Step six: and repeating the second step to the fifth step to realize the circulation of the processing period.

The above-mentioned embodiments, objects, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above-mentioned embodiments are only illustrative of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.