阅读说明：本技术 一种基于Boost和RC电路的微细电火花脉冲电源 (Fine electric spark pulse power supply based on Boost and RC circuit ) 是由 杨飞 邵佳钰 汪志鹏 史顺飞 吴鹏程 覃德凡 王一娉 李宏良 方斌 于 2020-01-20 设计创作，主要内容包括：本发明公开了一种基于Boost和RC电路的微细电火花脉冲电源,其特征在于,包括主功率回路、驱动电路、辅助直流电压源、FPGA控制器,所述主功率回路包括升压充电电路和放电回路,其中升压充电电路采用Boost电路,用于调节辅助直流电压源提供的电压,给放电回路中充电；所述放电回路采用RC电路用于给间隙提供击穿电压和击穿后的放电能量；辅助直流电压源用于给主功率回路以及驱动电路供电；FPGA控制器用于根据给定的目标参数来输出PWM控制信号给驱动电路；驱动电路对PWM控制信号进行数字隔离和放大,产生驱动信号驱动主功率回路中开关管的导通和关断。本发明提高了充电电压的可控性和能量调节精度,提高了加工精度和加工质量。(The invention discloses a micro electric spark pulse power supply based on a Boost circuit and an RC (resistor-capacitor) circuit, which is characterized by comprising a main power loop, a driving circuit, an auxiliary direct-current voltage source and an FPGA (field programmable gate array) controller, wherein the main power loop comprises a Boost charging circuit and a discharging loop, and the Boost charging circuit adopts the Boost circuit and is used for adjusting the voltage provided by the auxiliary direct-current voltage source and charging the discharging loop; the discharge loop adopts an RC circuit to provide breakdown voltage and discharge energy after breakdown for the gap; the auxiliary direct-current voltage source is used for supplying power to the main power loop and the driving circuit; the FPGA controller is used for outputting a PWM control signal to the drive circuit according to a given target parameter; the driving circuit carries out digital isolation and amplification on the PWM control signal to generate a driving signal to drive the switch tube in the main power loop to be switched on and switched off. The invention improves the controllability and the energy regulation precision of the charging voltage and improves the processing precision and the processing quality.)

1. A micro electric spark pulse power supply based on a Boost circuit and an RC circuit is characterized by comprising a main power loop, a driving circuit, an auxiliary direct current voltage source and an FPGA controller, wherein the main power loop comprises a Boost charging circuit and a discharging loop, and the Boost charging circuit adopts the Boost circuit and is used for adjusting the voltage provided by the auxiliary direct current voltage source and charging the discharging loop; the discharge loop adopts an RC circuit to provide breakdown voltage and discharge energy after breakdown for the gap; the auxiliary direct-current voltage source is used for supplying power to the main power loop and the driving circuit; the FPGA controller is used for outputting a PWM control signal to the drive circuit according to a given target parameter; the driving circuit carries out digital isolation and amplification on the PWM control signal to generate a driving signal to drive the switch tube in the main power loop to be switched on and switched off.

2. The Boost and RC circuit based fine spark-erosion pulse power supply of claim 1, wherein the Boost charging circuit comprises a first switching tube (Q)₁) A second switch tube (Q)₂) A first inductor (L)₁) Input capacitance (C)_in) A first diode (D)₁) Output capacitance (C)_out) Input capacitance (C)_in) Connected in parallel to the positive and negative ends of the auxiliary DC voltage source, the auxiliary DC voltage source has a first end grounded and the other end connected to the first inductor (L)₁) Connected to each other, a first inductance (L)₁) The other end is connected with a first switch tube (Q)₁) Connected, a first anti-reflux diode (D)₁) And a first inductor (L)₁) And a first switch tube (Q)₁) Is connected with the cathode of the second switch tube (Q)₂) Connected to a second switching tube (Q)₂) Another terminal of (C) and an output capacitor (C)_out) Connection, capacitance (C)_out) The other end is grounded.

3. Fine spark-pulse power supply based on Boost and RC circuit according to claim 1 characterized in that the discharge loop comprises a third switching tube (Q)₃) And a fourth switching tube (Q)₄) Deionization switch tube (Q)₅) Charging resistor (R)_ch) And a charging capacitor (C)_ch) A second diode (D)₂) Charging resistance (R)_ch) Connected with the output end of the Boost circuit, and the other end is connected with a third switching tube (Q)₃) Connected, a third switching tube (Q)₃) Another terminal of (C) and a charging capacitor (C)_ch) Connected to charge a capacitor (C)_ch) Is grounded, a fourth switching tube (Q)₄) And a third switching tube (Q)₃) And a charging capacitor (C)_ch) Is connected with the other end of the first reverse current prevention diode (D)₂) Anode of (2), cathode connection gap of diode, deionization switch tube (Q)₅) Connected in parallel at both ends of the gap.

4. According to claim 2The micro electric spark pulse power supply based on the Boost circuit and the RC circuit is characterized in that the first switching tube (Q)₁) A second switch tube (Q)₂) An N-channel MOSFET model IPP60R74C6 from infineon was chosen.

5. Fine spark-pulse power supply based on Boost and RC circuit according to claim 3 characterized by the third switching tube (Q)₃) And a fourth switching tube (Q)₄) Deionization switch tube (Q)₅) An N-channel MOSFET from ON Semiconductor, model FCP165N65S3, was selected.

6. The Boost and RC circuit based fine spark-pulse power supply according to claim 2, characterized in that the first inductance (L)₁) The model number of Sunlord company is MPH201206S1R0 MT.

7. The Boost and RC circuit based fine spark pulse power supply of claim 2 or 3, wherein the diode is selected as FFP30S 60S.

8. The Boost and RC circuit based fine electric spark pulse power supply of claim 1, wherein the FPGA is selected to be EP4CE15F23C8.

9. A gap machining method of a micro electric spark pulse power supply based on a Boost circuit and an RC circuit is characterized by comprising the following specific steps:

the method comprises the following steps: the FPGA controller generates multiple paths of PWM signals, and the signals are amplified by the driving circuit to drive a first switching tube (Q) of the main power loop₁) Conducting, fourth switching tube (Q)₄) Conducting, second switch tube (Q)₂) Off, third switching tube (Q)₃) Off, fifth switching tube (Q)₅) And turning off the direct current voltage to the first inductor (L) in the Boost circuit₁) Charging, namely boosting the voltage of a Boost circuit, discharging the RC circuit at the same time, and when the gap voltage reaches the gap breakdown voltage, performing gap breakdown discharging;

step two: when the output voltage of the Boost circuit reaches a set threshold value, the Boost circuit is switched to an RC (resistor-capacitor) charging mode, a controller FPGA (field programmable gate array) generates corresponding multi-path PWM (pulse width modulation) signals, and the multi-path PWM signals are amplified by a driving circuit to drive a first switching tube (Q) of a main power loop₁) Off, fourth switching tube (Q)₄) Off, second switching tube (Q)₂) Conducting, third switching tube (Q)₃) Conducting, fifth switching tube (Q)₅) Turn off, at which time the RC charging circuit is turned on and the output voltage (V) of the Boost circuit is used_out) Charging a capacitor (C) in an RC circuit_ch) Charging, namely switching to Boost modes of a Boost circuit and discharging modes of an RC circuit after RC charging is finished;

step three: after RC discharge is finished, the gap is deionized before entering the next discharge period, the controller FPGA generates a corresponding PWM signal, and the PWM signal is amplified by the driving circuit to drive a first switching tube (Q) of the main power loop₁) A second switch tube (Q)₂) And a third switching tube (Q)₃) And a fourth switching tube (Q)₄) Off, fifth switching tube (Q)₅) Conducting to enable the voltage at the two ends of the gap to be zero, entering a deionization stage and preparing for discharging in the next period;

step four: and repeating the three steps to realize the cycle of the processing period.

Technical Field

The invention relates to a high-frequency pulse power supply, in particular to a micro electric spark pulse power supply based on a Boost circuit and an RC circuit.

Background

The pulse power supply is used as a core part of the electric spark machine tool, and the design of the pulse power supply has important influence on the roughness of a machined surface, the damage degree of a tool electrode, the machining precision, the machining efficiency and the electric energy utilization rate. The high requirement on the machining precision means that the energy of single discharge of a pulse power supply is small enough and can be finely adjusted, while the micro electric spark machining pulse power supply in the current market mostly adopts a relaxation type topological structure, the energy of single discharge is small, the pulse power supply is suitable for micro machining, but the energy is uncontrollable, and the machining efficiency is low.

Disclosure of Invention

The invention aims to provide a micro electric spark pulse power supply based on a Boost circuit and an RC circuit.

The technical solution for realizing the purpose of the invention is as follows: a micro electric spark pulse power supply based on a Boost circuit and an RC circuit comprises a main power loop, a driving circuit, an auxiliary direct current voltage source and an FPGA controller, wherein the main power loop comprises a Boost charging circuit and a discharging loop, the Boost charging circuit adopts the Boost circuit and is used for adjusting the voltage provided by the auxiliary direct current voltage source and charging the discharging loop; the discharge loop adopts an RC circuit to provide breakdown voltage and discharge energy after breakdown for the gap; the auxiliary direct-current voltage source is used for supplying power to the main power loop and the driving circuit; the FPGA controller is used for outputting a PWM control signal to the drive circuit according to a given target parameter; the driving circuit carries out digital isolation and amplification on the PWM control signal to generate a driving signal to drive the switch tube in the main power loop to be switched on and switched off.

The boost charging circuit comprises a first switch tube Q₁A second switch tube Q₂First inductor L₁An input capacitor C_inA first diode D₁Output capacitance C_outInput capacitance C_inConnected in parallel to the positive and negative ends of the auxiliary DC voltage source, the auxiliary DC voltage source is grounded at one end, and the other end is connected with the first inductor L₁Connected, a first inductor L₁The other end and the first switch tube Q₁Connected, a first anti-reflux diode D₁Anode and first inductor L₁And a first switching tube Q₁Is connected with the cathode of the second switch tube Q₂Connected with a second switch tube Q₂The other end of (1) and an output capacitor C_outConnection, capacitance C_outThe other end is grounded.

The discharge circuit comprises a third switching tube Q₃And a fourth switching tube Q₄Deionization switch tube Q₅Charging resistor R_chAnd a charging capacitor C_chA second diode D₂Charging resistor R_chConnected with the output end of the Boost circuit, and the other end of the Boost circuit is connected with a third switching tube Q₃Connected, a third switching tube Q₃The other end of (C) and a charging capacitor (C)_chConnected to and charged with a capacitor C_chIs grounded, a fourth switching tube Q₄And a third switching tube Q₃And a charging capacitor C_chIs connected with the other end of the first reverse current prevention diode D₂Anode of the diode, cathode connection gap of the diode, deionization switch tube Q₅Connected in parallel at both ends of the gap.

The first switch tube Q₁A second switch tube Q₂An N-channel MOSFET model IPP60R74C6 from infineon was chosen.

The third switch tube Q₃And a fourth switching tube Q₄Deionization switch tube Q₅An N-channel MOSFET from ONSemiconductor, model FCP165N65S3, was selected.

The first inductor L₁The model number of Sunlord company is MPH201206S1R0 MT.

The diode is selected to be FFP30S 60S.

The FPGA is selected to be EP4CE15F23C8.

A clearance processing method of a micro electric spark pulse power supply based on a Boost circuit and an RC circuit comprises the following specific steps:

the method comprises the following steps: the FPGA controller generates a plurality of paths of PWM signals, after the signals are amplified by the driving circuit, the first switch tube of the main power loop is driven to be conducted, the fourth switch tube is conducted, the second switch tube is turned off, the third switch tube is turned off, the fifth switch tube is turned off, at the moment, in the Boost circuit, direct current voltage charges the first inductor, the Boost circuit boosts the voltage, the RC circuit discharges the voltage, and when the gap voltage reaches the gap breakdown voltage, the gap breakdown discharges the voltage;

step two: when the output voltage of the Boost circuit reaches a set threshold value, switching to an RC charging mode, generating corresponding multi-channel PWM signals by a controller FPGA, amplifying by a driving circuit, driving a first switching tube of a main power loop to be turned off, a fourth switching tube to be turned off, a second switching tube to be turned on, a third switching tube to be turned on, and a fifth switching tube to be turned off, wherein the RC charging circuit is turned on at the moment, a charging capacitor in the RC circuit is charged by the output voltage of the Boost circuit, and switching to the Boost circuit boosting and RC circuit discharging modes after RC charging is completed;

step three: after RC discharge is finished, the gap is subjected to deionization before entering the next discharge period, a controller FPGA generates a corresponding PWM signal, and after the PWM signal is amplified by a driving circuit, a first switching tube, a second switching tube, a third switching tube and a fourth switching tube of a main power loop are driven to be turned off, a fifth switching tube is turned on, so that the voltage at two ends of the gap is zero, and the gap enters a deionization stage to prepare for the discharge of the next period;

step four: and repeating the three steps to realize the cycle of the processing period.

Compared with the prior art, the invention has the following remarkable advantages: 1) the micro electric spark pulse power supply has small discharge energy, can finely adjust the energy and has strong controllability; 2) in the circuit topology of the Boost circuit combined RC pulse power supply, the RC charging circuit and the discharging circuit are respectively provided with a switching tube to realize energy controllability, the circuit structure is simple, and compared with the traditional topology, the circuit topology is easier to realize high-frequency discharge and improves the energy efficiency of a system; 3) according to the micro electric spark pulse power supply, the Boost circuit part is additionally arranged between the auxiliary direct current voltage source and the RC, so that the energy can be finely adjusted by controlling the output voltage, and the performance requirement of the direct current voltage source is reduced to a certain extent.

Drawings

Fig. 1 is a block diagram of a structure of a fine electric spark pulse power supply based on a Boost circuit and an RC circuit.

Fig. 2 is a topology diagram of the Boost circuit of the present invention.

FIG. 3 is a topology diagram of the RC circuit of the present invention.

Fig. 4 is a schematic diagram of a driving circuit of the present invention.

FIG. 5 is a schematic diagram of the discharge waveform of the micro electric spark finishing pulse power supply of the present invention.

Detailed Description

The invention is further described with reference to the following figures and specific examples.

As shown in fig. 1, a micro electric spark pulse power supply based on a Boost circuit and an RC circuit comprises a main power circuit, a driving circuit, an auxiliary dc voltage source, and an FPGA controller, wherein the main power circuit comprises a Boost charging circuit and a discharging circuit, wherein the Boost charging circuit adopts the Boost circuit and is used for adjusting the voltage provided by the auxiliary dc voltage source to charge the discharging circuit; the discharge loop adopts an RC circuit to provide breakdown voltage and discharge energy after breakdown for the gap; the auxiliary direct-current voltage source is used for supplying power to the main power loop and the driving circuit; the FPGA controller is used for outputting a PWM control signal to the drive circuit according to a given target parameter; the driving circuit carries out digital isolation and amplification on the PWM control signal to generate a driving signal to drive the switch tube in the main power loop to be switched on and switched off.

As shown in fig. 2, the Boost charging circuit adopts a Boost circuit, and includes a first switching tube Q₁A second switch tube Q₂1 main power inductor first inductor L₁1 input voltage stabilizing capacitor input capacitor C_in1 first diode D of anti-reverse current diode₁An output voltage stabilizing capacitor output capacitor C_out. Through the adjustment of the duty ratio, the adjustment precision of the output voltage can reach 1V. Input capacitance C_inConnected in parallel to the positive and negative ends of the auxiliary DC voltage source, the auxiliary DC voltage source is grounded at one end, and the other end is connected with the first inductor L₁Connected, a first inductor L₁The other end and the first switch tube Q₁Connected, a first anti-reflux diode D₁Anode and first inductor L₁And a first switching tube Q₁Is connected with the cathode of the second switch tube Q₂Connected with a second switch tube Q₂The other end of (1) and an output capacitor C_outConnection, capacitance C_outThe other end is grounded, and an output capacitor C of the Boost circuit_outAnd the voltage regulator is connected with the input end of the RC circuit, and further regulates the voltage provided by the auxiliary direct current voltage source by controlling the Boost circuit to charge a capacitor in the discharge loop. The energy released in the RC circuit in the gap breakdown process is adjusted by changing the output voltage value of the Boost circuit, and the voltage at two ends of the charging capacitor can be slightly adjusted by the Boost circuit, so that the requirement of finely adjusting the gap energy level is met, and the controllability of the system is improved.

As shown in FIG. 3, the discharge circuit adopts an RC circuit and comprises a third switching tube Q₃Fourth switch tube Q₄1 charging resistor R_chA charging capacitor C_chA reverse current prevention diode and a second diode D₂Deionization switch tube Q₅. Charging resistor R_chConnected with the output end of the Boost circuit, and the other end of the Boost circuit is connected with a third switching tube Q₃Connected, a third switching tube Q₃The other end of (C) and a charging capacitor (C)_chConnected to and charged with a capacitor C_chIs grounded at the other end, and a fourthSwitch tube Q₄And a third switching tube Q₃And a charging capacitor C_chIs connected with the other end of the first reverse current prevention diode D₂Anode of the diode, cathode connection gap of the diode, deionization switch tube Q₅Connected in parallel at both ends of the gap. By turning on the third switch tube Q on the RC charging loop₃Turning on and charging the capacitor C_chCharging is carried out, and after the charging is finished, the third switching tube Q₃Turn-off, fourth switch tube Q₄Conducting, when the voltage between the electrode and the workpiece reaches the breakdown voltage, the gap breaks down and discharges, and the workpiece is ablated; the two ends of the gap are also connected with a deionization switch tube Q in parallel₅And after the discharge is finished, the gap voltage is pulled to 0V, so that a rapid deionization channel is provided for the gap current.

In the main power circuit, the switching tube Q₁、Q₂An N-channel MOSFET (metal-oxide-semiconductor field effect transistor) with the model number of IPP60R74C6 and the drain-source voltage V of the same is selected by infineon_DSUp to 600V, rated current I_D57.7A, the working frequency is up to 1MHz, and the high-frequency high-voltage micro-electro-discharge machining device can be used in high-frequency, high-voltage and low-current micro-electro-discharge machining. Switch tube Q₃、Q₄、Q₅The N-channel MOSFET with the model number of FCP165N65S3 and the drain-source voltage resistance V is selected from ONSemiconductor_DSUp to 650V, rated current I_DWas 19A. The first inductor is selected from a Sunlord model of MPH201206S1R0MT, the inductance value is 1 muH, the diode is selected from FFP30S60S, the reverse withstand voltage is 600V, and the forward continuous conduction current is 30A.

And signals for controlling the on-off of the MOS tube in the power loop are generated by the FPGA controller. The FPGA selects the model number EP4CE15F23C8 as a high-speed processor of the Altera corporation CycleIV series, the clock frequency of the high-speed processor reaches 472MHz, and two paths of high-speed and high-precision AD conversion chips are arranged for inputting sampling signals.

As shown in fig. 4, for the driving circuit, the present invention uses a high-low end driving chip with isolation, here, a gate driving IC chip with a model of UCC21521, which is available from texas instruments, receives the PWM output signal of the FPGA, amplifies the PWM output signal by the driving chip, and drives the switching tube in the power circuit. The grid driving chip is a dual-channel, high-speed, internally isolated and grid driving chip with an enabling pin, the bandwidth is up to 5MHz, the isolation voltage is up to 5.7kV, and the surge anti-interference voltage is 12.8 kV. The driving chip can generate high-end and low-end driving at the same time, and the primary side and the secondary side are isolated, so that the interference between a main circuit and a control circuit is reduced.

According to the micro electric spark pulse power supply based on the Boost circuit and the RC circuit, the Boost circuit is adopted to finely adjust the charging voltage, so that the fine control of the energy level is realized, and the controllability and the precision of processing are improved; the Boost circuit can Boost the charging voltage, so that the auxiliary direct-current voltage source is not needed to provide high voltage, the voltage requirement on the Boost circuit is loose, and the control is flexible and reliable; a diode is connected in series with the output side of the RC circuit, so that the current reversal caused by the gap voltage oscillation can be prevented, and the RC circuit is simple in structure, free of resistance, high in efficiency and energy-saving, and stores energy through a capacitor.

Fig. 5 is a schematic diagram of a gap voltage current waveform of a processing cycle, in a switching cycle, an arc striking stage is started, after charging of a charging capacitor is completed, when voltage across a gap reaches breakdown voltage, gap breakdown occurs, the gap voltage rapidly drops to a holding voltage, at the moment, gap current also rapidly rises, the process is gap breakdown discharging, and when the gap current returns to 0, the gap discharging process is ended, and the gap enters a deionization stage. The working process of the micro electric spark pulse power supply based on the Boost circuit and the RC circuit comprises the following specific steps:

the method comprises the following steps: the controller FPGA generates corresponding multi-channel PWM signals, and after the signals are amplified by the driving circuit, the first switching tube of the main power loop is driven to be switched on, the fourth switching tube is driven to be switched on, the second switching tube is switched off, the third switching tube is switched off, and the fifth switching tube is switched off. In the Boost circuit, the direct-current voltage charges the first inductor, and the Boost circuit boosts the voltage. In the Boost stage, a third switching tube of the RC circuit is turned off, a fourth switching tube of the RC circuit is turned on, a charging circuit is turned off, a discharging circuit is turned on, a charging capacitor is discharged, the discharging process in the RC circuit is carried out simultaneously, and when the gap voltage reaches the gap breakdown voltage, the gap breakdown is discharged. The charging time is calculated and determined by the output voltage value required by actual production. When the charging time of the first inductor is over, the first switch tube is turned off, the second switch tube is turned on, the Boost circuit provides a forward input voltage which can be accurately adjusted for the RC circuit,

step two: and when the output voltage of the Boost circuit reaches a set threshold value, switching to an RC (resistor-capacitor) charging mode. The controller FPGA generates corresponding multi-channel PWM signals, and after the signals are amplified by the driving circuit, the first switching tube of the main power loop is driven to be turned off, the fourth switching tube is driven to be turned off, the second switching tube is driven to be turned on, the third switching tube is driven to be turned on, and the fifth switching tube is driven to be turned off. And the RC charging loop is conducted, and the output voltage of the Boost circuit charges a charging capacitor in the RC circuit. The energy released at the gap and the roughness of the workpiece surface finish are adjusted by controlling the amount of charged energy in the RC circuit. After the RC is charged, switching to a Boost circuit boosting mode and an RC circuit discharging mode;

step three: after RC discharge is finished, the gap needs to be subjected to deionization before entering the next discharge period, the controller FPGA generates corresponding PWM signals, after the PWM signals are amplified by the driving circuit, the first switch tube, the second switch tube, the third switch tube and the fourth switch tube of the main power loop are driven to be turned off, the fifth switch tube is turned on, the voltage at the two ends of the gap is zero, and the gap enters a deionization stage to prepare for the discharge of the next period.

Step four: and repeating the three steps to realize the cycle of the processing period.