Vacuum plasma excitation power supply

Abstract

This invention discloses a vacuum plasma excitation power supply, relating to the field of vacuum plasma, comprising: a buck variable power circuit that converts an external fixed DC power supply into an adjustable DC power output; an H-bridge boost circuit that converts the DC voltage output by the buck variable power circuit into a fixed-frequency AC voltage, which is then output to the vacuum chamber via a boost transformer; a power feedback circuit that collects the DC voltage and current signals output by the buck variable power circuit, calculates the power feedback signal, and transmits it to the buck variable power circuit; an output feedback circuit that collects the AC voltage and current signals at the vacuum chamber end and feeds them back to the buck variable power circuit for closed-loop control and over-limit safety protection; and a main control circuit that collects the power feedback and output feedback signals and executes the control process. This invention can achieve high-precision and high-stability vacuum plasma discharge for use in vacuum plasma fine surface treatment.

Description

Technical Field

[0001] This invention belongs to the field of vacuum plasma, and specifically relates to a vacuum plasma excitation power supply. Background Technology

[0002] Vacuum plasma surface treatment generates plasma by exciting process gas with an electric field within a low-pressure chamber. Electrons, ions, and active free radicals in the plasma are then used to clean, activate, or functionalize material surfaces. This technology operates at relatively low temperatures and is applicable to metals, polymers, ceramics, and composite materials. Furthermore, it produces no liquid waste and has found widespread application in semiconductor packaging, printed circuit boards, automotive electronics, medical devices, and aerospace components.

[0003] Plasma discharge power directly affects the density and energy distribution of active particles, making it a key process parameter determining the treatment effect. Low power results in insufficient surface activation and decreased uniformity within the same batch; high power poses a risk of thermal damage to the workpiece and easily induces abnormal arc discharge, causing surface ablation or electrode damage. In reactive sputtering coating and other processes, as the cathode surface is gradually covered by an insulating dielectric layer, charge accumulation cannot be released, leading to a gradual contraction of the discharge channel, resulting in "anode disappearance" and frequent arc extinction, severely impacting film quality. Therefore, precise and stable closed-loop control of vacuum plasma discharge power is essential for achieving refined surface treatment.

[0004] Currently, the most widely used excitation power supplies are DC, radio frequency (RF), and intermediate frequency (IF), each with its limitations. DC power supplies have a simple topology but cannot effectively address the charge accumulation problem caused by the equivalent capacitance of the insulating layer, leading to frequent arc discharges and severe target poisoning during reactive sputtering. RF power supplies (e.g., 13.56MHz) can penetrate the charge accumulation in the insulating layer, but the impedance matching network is complex, and transmission loss and electromagnetic interference become significant with increasing power, thus raising the overall cost. IF power supplies (approximately 40kHz~400kHz) operate at frequencies between the two: on the one hand, they have the charge neutralization capability of an alternating electric field, suppressing arc discharge; on the other hand, they avoid the high losses and matching difficulties of the RF band, thus gradually becoming mainstream in medium power density vacuum plasma applications.

[0005] However, existing medium-frequency plasma power supplies still have significant shortcomings in terms of power closed-loop control accuracy and dynamic response. First, most power supplies only sample from the power output, failing to directly monitor the actual voltage and current at the vacuum chamber end. This inevitably leads to discrepancies between the feedback signal and the actual plasma load state. When chamber pressure fluctuates, process gas composition changes, or workpiece loading varies, the power supply's transient response to the actual load is insufficient, resulting in significantly increased discharge power fluctuations. Second, the few solutions with chamber-end monitoring typically have only one feedback channel, making it impossible to simultaneously perform closed-loop discharge power regulation and chamber-end over-limit safety protection within the same control cycle, thus limiting the scope of control functionality. Third, the collaborative design of Buck variable-power topology and H-bridge boost stage in medium-frequency plasma power supplies is still immature in engineering applications. In particular, designs integrating Buck pre-stage power regulation, H-bridge boost, power-side feedback, and chamber output-side feedback into a unified closed-loop control architecture are relatively rare. When partial arc extinguishing or over-current uncontrolled discharge occurs, existing power supplies mostly rely on overload trip protection, lacking fine-grained limiting methods at the parameter level. The control granularity is difficult to meet the high requirements for surface treatment consistency in applications such as semiconductor packaging.

[0006] In summary, if real-time calculation of the discharge power at the output of the variable power circuit and real-time feedback of the voltage and current at the vacuum chamber can be achieved within a medium-frequency power supply architecture, and the Buck variable power circuit and H-bridge boost stage can be adjusted in coordination with the two information sources within the same closed-loop control cycle, it is expected that the control accuracy of the discharge power and the response speed of the safety protection can be improved simultaneously. Summary of the Invention

[0007] To achieve the above objectives, this invention proposes a vacuum plasma excitation power supply, comprising: The buck converter circuit is used to convert an external fixed DC power supply into an adjustable DC power supply. The adjustment feedback comes from the output power sampling of the subsequent stage and the voltage and current feedback signals at the vacuum chamber.

[0008] The H-bridge boost current is used to convert the DC voltage output from the buck variable power circuit into a fixed-frequency AC voltage, which is then output to the vacuum chamber via a boost transformer.

[0009] The power feedback circuit is used to collect the DC voltage and current signals output by the buck power converter circuit, calculate the power feedback signal, and transmit it to the buck power converter circuit.

[0010] The output feedback circuit is used to collect the AC voltage and circuit signals at the vacuum chamber end and feed them back to the Buck power converter circuit for closed-loop control and over-limit protection.

[0011] The main control circuit is used to acquire power feedback and output feedback signals, and execute the control process.

[0012] Preferably, in the buck variable power circuit: The positive terminal of the input DC power supply, DC_IN+, is connected to one end of fuse F2, and the negative terminal, DC_IN-, is connected to the main circuit's reference ground, GND. The other end of the fuse is connected to the positive terminals of input filter capacitors C42, C44, and C45, forming the positive terminal of the DC bus, DCBUS, and simultaneously connected to one end of the current-limiting resistor R90 in the power indicator circuit. Filter capacitors C42, C44, and C45 are connected in parallel. The negative terminals of input filter capacitors C42, C44, and C45 are connected to the main circuit's reference ground, GND. The current-limiting resistors R90, R91, and R92 are connected in series, forming a large equivalent resistance to prevent overheating and damage. These resistors are then connected in series to the anode of the power indicator D30, and the cathode of D30 is connected back to the main circuit's reference ground, GND. The positive terminal of input filter capacitor C30 is connected to the positive terminal of the DC bus, DCBUS, and the negative terminal is connected to the main circuit's reference ground, GND. The drain of the main power MOSFET Q1 is connected to the positive terminal of the DC bus DCBUS, and the source of the secondary power MOSFET Q2 is connected to the reference ground GND of the main circuit. The gate of the main power MOSFET Q1 is connected to the corresponding drive signal GBUCK1R, and the drive signal circuit EBUCK1 is connected to the source of the main power MOSFET Q1. The gate of the secondary power MOSFET Q2 is connected to the corresponding drive signal GBUCK2R, and the drive signal circuit EBUCK2 is connected to the source of the secondary power MOSFET Q2. The source of the main power MOSFET Q1 is connected to the drain of the secondary power MOSFET Q2, forming the external output hotspot SW. An external power inductor is connected through external terminals P5 and P6. External terminal P5 is connected to one end of the external power inductor, and external terminal P6 is connected to the other end of the external power inductor. At the same time, P6 is connected to the positive terminal DCBUCK of the buck filter capacitors C1, C2, C3, C4, C5, C6, C7, and C8. Buck filter capacitors C1, C2, C3, C4, C5, C6, C7, and C8 are connected in parallel. The cathodes of these capacitors are connected to the main circuit's reference ground, GND. The positive output of the Buck converter circuit is DCBUCK, and the negative output is GND, which will be connected to the H-bridge boost circuit.

[0013] Preferably, in the H-bridge boost circuit: The positive terminal of the input filter capacitor C43 is connected to the positive output terminal DCBUCK of the buck converter circuit, and the negative terminal of the input filter capacitor C43 is connected to the negative output terminal GND of the buck converter circuit. The four MOSFETs Q5, Q6, Q7, and Q8 of the H-bridge operate in an angularly symmetrical, complementary configuration, producing a 40kHz square wave with a dead time. The drains of Q5 and Q6 are connected to DCBUCK, and the sources of Q7 and Q8 are connected to GND. The gate of Q5 is connected to the corresponding drive signal GFB1R, and the drive signal loop EFB1 is connected to the source of Q5. The gate of Q6 is connected to the corresponding drive signal GFB3R, and the drive signal loop EFB3 is connected to the source of Q6. The gate of Q7 is connected to the corresponding drive signal GFB2R, and the drive signal loop EFB2 is connected to the source of Q7. The gate of Q8 is connected to the corresponding drive signal GFB4R, and the drive signal loop EFB4 is connected to the source of Q8. Each of the four MOSFETs in the H-bridge has a high-voltage non-polar capacitor C40, C41, C51, and C52 connected between its drain and source. The source of Q5 is connected to the drain of Q7, forming the front arm of the H-bridge. The source of Q6 is connected to the drain of Q8, forming the rear arm of the H-bridge. The front arm is directly connected to pin 2 of output terminal P19, and the rear arm is connected to one end of DC blocking capacitors C47 and C49, which are connected in parallel. The other end of the DC blocking capacitors is connected to pin 1 of output terminal P19. Output terminal P19 is directly connected to the primary side of an external boost transformer, which directly drives the vacuum plasma chamber.

[0014] Preferably, in the power feedback circuit: The power feedback circuit directly acquires the output voltage and current signals of the buck converter circuit in a differential form. The voltage differential signals are OUTP and OUTN, which are connected to the two terminals of the common-mode inductor L2 respectively, and then passed to the RC differential filter circuit composed of R69, R75, C47, and C48. The OUTN signal is filtered by the first coil of the common-mode inductor L2 and then connected to one end of R69; the OUTP signal is filtered by the second coil of the common-mode inductor L2 and then connected to one end of R75. The differential capacitors C47 and C48 are connected in parallel. The other end of R69 is connected to one end of the differential capacitors C47 and C48 and then to the inverting input of the precision operational amplifier U10; the other end of R75 is connected to the other end of the differential capacitors C47 and C48 and then to the non-inverting input of the precision operational amplifier U10. A bleed capacitor C51 is connected to the non-inverting input of precision operational amplifier U10, and a bleed capacitor C50 is connected to the signal reference ground SGND. Matching resistor R68 is connected to pins 2 and 3 of precision operational amplifier U10, and filter capacitor C46 is connected to pins 8 and 5 of precision operational amplifier U10. The output of precision operational amplifier U10 is filtered using a low-pass filter composed of resistor R74 and capacitor C49. Pin 7 of precision operational amplifier U10 is connected to one end of filter resistor R74, and the other end of filter resistor R74 is connected to one end of filter capacitor C49, generating a voltage sampling signal VACBUS that is linearly related to the output voltage. The other end of filter capacitor C49 is connected to the signal reference ground SGND. The current differential signals SGND and VIOUT are connected to the two terminals of the common-mode inductor L1, respectively, and then passed to the RC differential filter circuit composed of R64, R66, C40, and C41. The SGND signal, after being filtered by coil 1 of the common-mode inductor L1, is connected to one end of R64; the VIOUT signal, after being filtered by coil 2 of the common-mode inductor L1, is connected to one end of R66. Differential capacitors C40 and C41 are connected in parallel. The other end of R64 is connected to one end of differential capacitors C40 and C41, and then to the inverting input of precision operational amplifier U9. The other end of R66 is connected to the other end of differential capacitors C40 and C41, and then to the non-inverting input of precision operational amplifier U9. A bleed capacitor C43 is connected to the signal reference ground SGND at the non-inverting input of precision operational amplifier U9, and a bleed capacitor C42 is connected to the signal reference ground SGND at the inverting input of precision operational amplifier U9. Matching resistor R62 is connected to pins 2 and 3 of precision op-amp U9, and filter capacitor C38 is connected to pins 8 and 5 of precision op-amp U9. The output of precision op-amp U9 is filtered using a low-pass filter composed of R65 and C39. Pin 7 of precision op-amp U9 is connected to one end of filter resistor R65, and the other end of filter resistor R65 is connected to one end of filter capacitor C39, generating a voltage sampling signal IACBUS that is linearly related to the output voltage. The other end of filter capacitor C39 is connected to signal reference ground SGND.

[0015] Preferably, in the output feedback circuit: The output feedback circuit directly acquires the AC voltage and current signals from the vacuum chamber end in an isolated sampling manner. The isolated voltage sampling signal is output as HVSENSE+ and HVSENSE- via an isolation transformer. This isolated voltage sampling signal is then sent to an uncontrolled rectifier bridge circuit composed of D9, D10, D13, and D14. HVSENSE+ is connected to the anode of D9 and the cathode of D13, and HVSENSE- is connected to the anode of D10 and the cathode of D14. The cathodes of D9 and D10 are connected in parallel to form the positive output of the rectifier, and the anodes of D13 and D14 are connected in parallel to form the negative output of the rectifier. After rectification and filtering, the AC signal yields a DC feedback voltage signal. The filter consists of R31, C41, C15, and C16, which are connected in parallel. Their anodes are connected to the positive output of the rectifier bridge, and their cathodes are connected to the negative output of the rectifier bridge, which also serves as the reference ground SGND for the control circuit. The filtered DC feedback voltage is then divided by a series voltage divider network consisting of resistors R24, R28, R30, and R34 to obtain a linearly stepped-down DC feedback voltage signal. The resistors are connected in series as follows: one end of R24 is connected to the positive output of the rectifier bridge; the other end of R24 is connected to one end of R28; the other end of R28 is connected to one end of R30; the other end of R30 is connected to one end of R34, and also to one end of the subsequent filter resistor R29; the other end of R34 is connected to reference ground (SGND). A two-stage series filter system consisting of R29, C17, and R32, C19 filters the linearly stepped-down DC feedback voltage signal and sends it to the non-inverting input of operational amplifier U2.2. The other end of R29 is connected to one end of C17, and also to one end of R32; the other end of C17 is connected to reference ground (SGND); the other end of R32 is connected to one end of C19, and also to the non-inverting input of operational amplifier U2.2. The output of the operational amplifier is fed back to the inverting input via feedback resistor R22. Simultaneously, the inverting input is divided by resistor R25 and sent to reference ground SGND. A DC voltage signal, denoted as HVSENSE, linearly proportional to the load voltage of the vacuum chamber, can be obtained at the output of operational amplifier U2.2. HVSENSE passes through a low-pass filter composed of resistors R33 and C18 and is then sent to the inverting input of voltage comparator U1.2. The non-inverting input of voltage comparator U1.2 uses a fixed series voltage divider network composed of resistors R17, R18, and R19 to obtain a fixed hardware protection threshold. One end of R19 is connected to +12V, and the other end is connected to one end of R18. The other end of R18 is connected to one end of R17 and one end of R26. The other end of R17 is connected to reference ground SGND, and the other end of R26 is the non-inverting input of voltage comparator U1.2, connected to one end of filter capacitor C13, and the other end of C13 is connected to reference ground SGND. The isolation current signal is output as CHF+ and CHF- after passing through a Hall sensor element. The isolation current sampling signal is sent to an uncontrolled rectifier bridge circuit composed of D1, D2, D3, and D4. CHF+ is connected to the anode of D4 and the cathode of D2, and CHF- is connected to the anode of D3 and the cathode of D1.The cathodes of D3 and D4 are connected in parallel to form the positive output of the rectifier, and the anodes of D1 and D2 are connected in parallel to form the negative output of the rectifier. The AC signal is rectified and filtered to obtain a DC feedback current signal. The filter consists of resistors R6, C3, and C4, which are connected in parallel. Their anodes are connected to the positive output of the rectifier bridge, and their cathodes are connected to the negative output of the rectifier bridge, which also serves as the reference ground SGND for the control circuit. The filtered DC feedback signal is then filtered by a two-stage series filter system composed of R9, C6, and R10, and C7 before being sent to the non-inverting input of operational amplifier U2.1. One end of R9 is connected to the positive output of the rectifier bridge, and the other end is connected to one end of C6 and one end of R10. The other end of C6 is connected to the reference ground SGND, and the other end of R10 is connected to one end of C7 and also to the non-inverting input of operational amplifier U2.1. The output of the operational amplifier is fed back to the inverting input via feedback resistor R4, and simultaneously, the inverting input is divided by resistor R5 and sent to the reference ground SGND. A DC current signal, denoted as ISENSE, that is linearly proportional to the current at the vacuum chamber load terminal can be obtained at the output of op-amp U2.1. Pin 8 of op-amp U2.1 is connected to capacitor C1, and the other end of C1 is connected to reference ground SGND. ISENSE is then sent to the inverting input of voltage comparator U1.1 after passing through a low-pass filter composed of resistors R11 and C5. The non-inverting input of voltage comparator U1.1 uses a fixed series voltage divider network composed of resistors R1, R2, and R3 to obtain a fixed hardware protection threshold. One end of R3 is connected to +12V, and the other end is connected to one end of R2. The other end of R2 is connected to one end of R1 and also to one end of R6. The other end of R1 is connected to reference ground SGND.

[0016] Preferably, in the main control MCU circuit: The main control circuit serves as the platform for the control algorithm, used to acquire feedback signals and control the buck converter circuit to adjust its output in real time. The VACBUS signal is sent to the PA3 port of the main control MCU for ADC sampling, and the IACBUS signal is sent to the PA2 port of the main control MCU for ADC sampling. The ISENSE signal is sent to the PA4 port of the main control MCU for ADC sampling, and the HVSENSE signal is sent to the PA5 port of the main control MCU for ADC sampling. Closed-loop control of the buck converter circuit and the H-bridge boost circuit is achieved through the output PWM signal.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention senses the vacuum plasma discharge power in real time, calculates the discharge power in real time by sampling the output voltage and current of the variable power circuit, performs real-time output feedback calculation by sampling the voltage and current at the vacuum cavity end, executes over-limit safety protection, and the variable power circuit performs real-time closed-loop control based on the vacuum plasma discharge power and the feedback information at the cavity end, thereby achieving high-precision and high-stability vacuum plasma discharge for use in vacuum plasma fine surface treatment. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the operation of the vacuum plasma excitation power supply described in this invention. Figure 2 This is the functional framework of the vacuum plasma excitation power supply system described in this invention; Figure 3 This is the vacuum plasma excitation power supply circuit structure described in the embodiments of the present invention. Detailed Implementation

[0019] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Example

[0020] This embodiment proposes a vacuum plasma excitation power supply, whose core adjustment unit is a sampling buck variable power circuit. It provides real-time feedback on plasma discharge power and cavity terminal voltage current, achieving a plasma discharge power control accuracy of 0.5%, a discharge power adjustment range of 0-1000W, a safety protection response speed of 50µs, and a start-stop process of 1 second. Specifically, it is a vacuum plasma excitation power supply, comprising: The buck converter circuit is used to convert an external fixed DC power supply into an adjustable DC power supply. The adjustment feedback comes from the output power sampling of the subsequent stage and the voltage and current feedback signals at the vacuum chamber.

[0021] The H-bridge boost current is used to convert the DC voltage output from the buck variable power circuit into a fixed-frequency AC voltage, which is then output to the vacuum chamber via a boost transformer.

[0022] The power feedback circuit is used to collect the DC voltage and current signals output by the buck power converter circuit, calculate the power feedback signal, and transmit it to the buck power converter circuit.

[0023] The output feedback circuit is used to collect the AC voltage and circuit signals at the vacuum chamber end and feed them back to the Buck power converter circuit for closed-loop control and over-limit protection.

[0024] The main control circuit is used to acquire power feedback and output feedback signals, and execute the control process.

[0025] Furthermore, in the buck variable power circuit: The positive terminal of the input DC power supply, DC_IN+, is connected to one end of fuse F2, and the negative terminal, DC_IN-, is connected to the main circuit's reference ground, GND. The other end of the fuse is connected to the positive terminals of input filter capacitors C42, C44, and C45, forming the positive terminal of the DC bus, DCBUS, and simultaneously connected to one end of the current-limiting resistor R90 in the power indicator circuit. Filter capacitors C42, C44, and C45 are connected in parallel. The negative terminals of input filter capacitors C42, C44, and C45 are connected to the main circuit's reference ground, GND. The current-limiting resistors R90, R91, and R92 are connected in series, forming a large equivalent resistance to prevent overheating and damage. These resistors are then connected in series to the anode of the power indicator D30, and the cathode of D30 is connected back to the main circuit's reference ground, GND. The positive terminal of input filter capacitor C30 is connected to the positive terminal of the DC bus, DCBUS, and the negative terminal is connected to the main circuit's reference ground, GND. The drain of the main power MOSFET Q1 is connected to the positive terminal of the DC bus DCBUS, and the source of the secondary power MOSFET Q2 is connected to the reference ground GND of the main circuit. The gate of the main power MOSFET Q1 is connected to the corresponding drive signal GBUCK1R, and the drive signal circuit EBUCK1 is connected to the source of the main power MOSFET Q1. The gate of the secondary power MOSFET Q2 is connected to the corresponding drive signal GBUCK2R, and the drive signal circuit EBUCK2 is connected to the source of the secondary power MOSFET Q2. The source of the main power MOSFET Q1 is connected to the drain of the secondary power MOSFET Q2, forming the external output hotspot SW. An external power inductor is connected through external terminals P5 and P6. External terminal P5 is connected to one end of the external power inductor, and external terminal P6 is connected to the other end of the external power inductor. At the same time, P6 is connected to the positive terminal DCBUCK of the buck filter capacitors C1, C2, C3, C4, C5, C6, C7, and C8. Buck filter capacitors C1, C2, C3, C4, C5, C6, C7, and C8 are connected in parallel. The cathodes of these capacitors are connected to the main circuit's reference ground, GND. The positive output of the Buck converter circuit is DCBUCK, and the negative output is GND, which will be connected to the H-bridge boost circuit.

[0026] Furthermore, in the H-bridge boost circuit: The positive terminal of the input filter capacitor C43 is connected to the positive output terminal DCBUCK of the buck converter circuit, and the negative terminal of the input filter capacitor C43 is connected to the negative output terminal GND of the buck converter circuit. The four MOSFETs Q5, Q6, Q7, and Q8 of the H-bridge operate in an angularly symmetrical, complementary configuration, producing a 40kHz square wave with a dead time. The drains of Q5 and Q6 are connected to DCBUCK, and the sources of Q7 and Q8 are connected to GND. The gate of Q5 is connected to the corresponding drive signal GFB1R, and the drive signal loop EFB1 is connected to the source of Q5. The gate of Q6 is connected to the corresponding drive signal GFB3R, and the drive signal loop EFB3 is connected to the source of Q6. The gate of Q7 is connected to the corresponding drive signal GFB2R, and the drive signal loop EFB2 is connected to the source of Q7. The gate of Q8 is connected to the corresponding drive signal GFB4R, and the drive signal loop EFB4 is connected to the source of Q8. Each of the four MOSFETs in the H-bridge has a high-voltage non-polar capacitor C40, C41, C51, and C52 connected between its drain and source. The source of Q5 is connected to the drain of Q7, forming the front arm of the H-bridge. The source of Q6 is connected to the drain of Q8, forming the rear arm of the H-bridge. The front arm is directly connected to pin 2 of output terminal P19, and the rear arm is connected to one end of DC blocking capacitors C47 and C49, which are connected in parallel. The other end of the DC blocking capacitors is connected to pin 1 of output terminal P19. Output terminal P19 is directly connected to the primary side of an external boost transformer, which directly drives the vacuum plasma chamber.

[0027] Furthermore, in the power feedback circuit: The power feedback circuit directly acquires the output voltage and current signals of the buck converter circuit in a differential form. The voltage differential signals are OUTP and OUTN, which are connected to the two terminals of the common-mode inductor L2 respectively, and then passed to the RC differential filter circuit composed of R69, R75, C47, and C48. The OUTN signal is filtered by the first coil of the common-mode inductor L2 and then connected to one end of R69; the OUTP signal is filtered by the second coil of the common-mode inductor L2 and then connected to one end of R75. The differential capacitors C47 and C48 are connected in parallel. The other end of R69 is connected to one end of the differential capacitors C47 and C48 and then to the inverting input of the precision operational amplifier U10; the other end of R75 is connected to the other end of the differential capacitors C47 and C48 and then to the non-inverting input of the precision operational amplifier U10. A bleed capacitor C51 is connected to the non-inverting input of precision operational amplifier U10, and a bleed capacitor C50 is connected to the signal reference ground SGND. Matching resistor R68 is connected to pins 2 and 3 of precision operational amplifier U10, and filter capacitor C46 is connected to pins 8 and 5 of precision operational amplifier U10. The output of precision operational amplifier U10 is filtered using a low-pass filter composed of resistor R74 and capacitor C49. Pin 7 of precision operational amplifier U10 is connected to one end of filter resistor R74, and the other end of filter resistor R74 is connected to one end of filter capacitor C49, generating a voltage sampling signal VACBUS that is linearly related to the output voltage. The other end of filter capacitor C49 is connected to the signal reference ground SGND. The current differential signals SGND and VIOUT are connected to the two terminals of the common-mode inductor L1, respectively, and then passed to the RC differential filter circuit composed of R64, R66, C40, and C41. The SGND signal, after being filtered by coil 1 of the common-mode inductor L1, is connected to one end of R64; the VIOUT signal, after being filtered by coil 2 of the common-mode inductor L1, is connected to one end of R66. Differential capacitors C40 and C41 are connected in parallel. The other end of R64 is connected to one end of differential capacitors C40 and C41, and then to the inverting input of precision operational amplifier U9. The other end of R66 is connected to the other end of differential capacitors C40 and C41, and then to the non-inverting input of precision operational amplifier U9. A bleed capacitor C43 is connected to the signal reference ground SGND at the non-inverting input of precision operational amplifier U9, and a bleed capacitor C42 is connected to the signal reference ground SGND at the inverting input of precision operational amplifier U9. Matching resistor R62 is connected to pins 2 and 3 of precision op-amp U9, and filter capacitor C38 is connected to pins 8 and 5 of precision op-amp U9. The output of precision op-amp U9 is filtered using a low-pass filter composed of R65 and C39. Pin 7 of precision op-amp U9 is connected to one end of filter resistor R65, and the other end of filter resistor R65 is connected to one end of filter capacitor C39, generating a voltage sampling signal IACBUS that is linearly related to the output voltage. The other end of filter capacitor C39 is connected to signal reference ground SGND.

[0028] Furthermore, in the output feedback circuit: The output feedback circuit directly acquires the AC voltage and current signals from the vacuum chamber end in an isolated sampling manner. The isolated voltage sampling signal is output as HVSENSE+ and HVSENSE- via an isolation transformer. This isolated voltage sampling signal is then sent to an uncontrolled rectifier bridge circuit composed of D9, D10, D13, and D14. HVSENSE+ is connected to the anode of D9 and the cathode of D13, and HVSENSE- is connected to the anode of D10 and the cathode of D14. The cathodes of D9 and D10 are connected in parallel to form the positive output of the rectifier, and the anodes of D13 and D14 are connected in parallel to form the negative output of the rectifier. After rectification and filtering, the AC signal yields a DC feedback voltage signal. The filter consists of R31, C41, C15, and C16, which are connected in parallel. Their anodes are connected to the positive output of the rectifier bridge, and their cathodes are connected to the negative output of the rectifier bridge, which also serves as the reference ground SGND for the control circuit. The filtered DC feedback voltage is then divided by a series voltage divider network consisting of resistors R24, R28, R30, and R34 to obtain a linearly stepped-down DC feedback voltage signal. The resistors are connected in series as follows: one end of R24 is connected to the positive output of the rectifier bridge; the other end of R24 is connected to one end of R28; the other end of R28 is connected to one end of R30; the other end of R30 is connected to one end of R34, and also to one end of the subsequent filter resistor R29; the other end of R34 is connected to reference ground (SGND). A two-stage series filter system consisting of R29, C17, and R32, C19 filters the linearly stepped-down DC feedback voltage signal and sends it to the non-inverting input of operational amplifier U2.2. The other end of R29 is connected to one end of C17, and also to one end of R32; the other end of C17 is connected to reference ground (SGND); the other end of R32 is connected to one end of C19, and also to the non-inverting input of operational amplifier U2.2. The output of the operational amplifier is fed back to the inverting input via feedback resistor R22. Simultaneously, the inverting input is divided by resistor R25 and sent to reference ground SGND. A DC voltage signal, denoted as HVSENSE, linearly proportional to the load voltage of the vacuum chamber, can be obtained at the output of operational amplifier U2.2. HVSENSE passes through a low-pass filter composed of resistors R33 and C18 and is then sent to the inverting input of voltage comparator U1.2. The non-inverting input of voltage comparator U1.2 uses a fixed series voltage divider network composed of resistors R17, R18, and R19 to obtain a fixed hardware protection threshold. One end of R19 is connected to +12V, and the other end is connected to one end of R18. The other end of R18 is connected to one end of R17 and one end of R26. The other end of R17 is connected to reference ground SGND, and the other end of R26 is the non-inverting input of voltage comparator U1.2, connected to one end of filter capacitor C13, and the other end of C13 is connected to reference ground SGND. The isolation current signal is output as CHF+ and CHF- after passing through a Hall sensor element. The isolation current sampling signal is sent to an uncontrolled rectifier bridge circuit composed of D1, D2, D3, and D4. CHF+ is connected to the anode of D4 and the cathode of D2, and CHF- is connected to the anode of D3 and the cathode of D1.The cathodes of D3 and D4 are connected in parallel to form the positive output of the rectifier, and the anodes of D1 and D2 are connected in parallel to form the negative output of the rectifier. The AC signal is rectified and filtered to obtain a DC feedback current signal. The filter consists of resistors R6, C3, and C4, which are connected in parallel. Their anodes are connected to the positive output of the rectifier bridge, and their cathodes are connected to the negative output of the rectifier bridge, which also serves as the reference ground SGND for the control circuit. The filtered DC feedback signal is then filtered by a two-stage series filter system composed of R9, C6, and R10, and C7 before being sent to the non-inverting input of operational amplifier U2.1. One end of R9 is connected to the positive output of the rectifier bridge, and the other end is connected to one end of C6 and one end of R10. The other end of C6 is connected to the reference ground SGND, and the other end of R10 is connected to one end of C7 and also to the non-inverting input of operational amplifier U2.1. The output of the operational amplifier is fed back to the inverting input via feedback resistor R4, and simultaneously, the inverting input is divided by resistor R5 and sent to the reference ground SGND. A DC current signal, denoted as ISENSE, that is linearly proportional to the current at the vacuum chamber load terminal can be obtained at the output of op-amp U2.1. Pin 8 of op-amp U2.1 is connected to capacitor C1, and the other end of C1 is connected to reference ground SGND. ISENSE is then sent to the inverting input of voltage comparator U1.1 after passing through a low-pass filter composed of resistors R11 and C5. The non-inverting input of voltage comparator U1.1 uses a fixed series voltage divider network composed of resistors R1, R2, and R3 to obtain a fixed hardware protection threshold. One end of R3 is connected to +12V, and the other end is connected to one end of R2. The other end of R2 is connected to one end of R1 and also to one end of R6. The other end of R1 is connected to reference ground SGND.

[0029] Furthermore, in the main control MCU circuit: The main control circuit serves as the platform for the control algorithm, used to acquire feedback signals and control the buck converter circuit to adjust its output in real time. The VACBUS signal is sent to the PA3 port of the main control MCU for ADC sampling, and the IACBUS signal is sent to the PA2 port of the main control MCU for ADC sampling. The ISENSE signal is sent to the PA4 port of the main control MCU for ADC sampling, and the HVSENSE signal is sent to the PA5 port of the main control MCU for ADC sampling. Closed-loop control of the buck converter circuit and the H-bridge boost circuit is achieved through the output PWM signal.

[0030] It should be noted that the above content merely illustrates the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. For those skilled in the art, various improvements and modifications can be made without departing from the principle of the present invention, and all such improvements and modifications fall within the scope of protection of the claims of the present invention.

Claims

1. A vacuum plasma excitation power supply, characterized in that, include: The buck converter circuit converts an external fixed DC power supply into an adjustable DC power supply. The H-bridge boost circuit converts the DC voltage output by the buck variable power circuit into a fixed-frequency AC voltage, which is then output to the vacuum chamber via a boost transformer. The power feedback circuit collects the DC voltage and current signals output by the buck power converter circuit, calculates the power feedback signal, and transmits it to the buck power converter circuit. The output feedback circuit collects the AC voltage and current signals at the vacuum chamber end and feeds them back to the buck power conversion circuit for closed-loop control and over-limit safety protection. The system also includes a main control circuit that collects the power feedback and output feedback signals and executes the control process.

2. The vacuum plasma excitation power supply according to claim 1, characterized in that, In the buck variable power circuit: the positive terminal DC_IN+ of the input DC power supply is connected to one end of fuse F2, and the negative terminal DC_IN- of the input DC power supply is connected to the reference ground GND of the main circuit; the other end of the fuse is connected to the positive terminals of input filter capacitors C42, C44, and C45, forming the positive terminal DCBUS of the DC bus; filter capacitors C42, C44, and C45 are connected in parallel, and their negative terminals are connected to the reference ground GND of the main circuit; current-limiting resistors R90, R91, and R92 are connected in series to the anode of power indicator D30, and the cathode of D30 is connected to the reference ground GND of the main circuit; the positive terminal of input filter capacitor C30 is connected to the positive terminal DCBUS of the DC bus, and the negative terminal is connected to the reference ground GND of the main circuit; the drain of the main power MOSFET Q1 is connected to the positive terminal DCBUS of the DC bus, and the source of the secondary power MOSFET Q2 is connected to the reference ground GND of the main circuit. D; The gate of the main power MOSFET Q1 is connected to the drive signal GBUCK1R, and the drive signal circuit EBUCK1 is connected to the source of the main power MOSFET Q1; the gate of the secondary power MOSFET Q2 is connected to the drive signal GBUCK2R, and the drive signal circuit EBUCK2 is connected to the source of the secondary power MOSFET Q2; the source of the main power MOSFET Q1 is connected to the drain of the secondary power MOSFET Q2, forming an external output hotspot SW; an external power inductor is connected through external terminals P5 and P6, and P6 is connected to the positive terminal DCBUCK of buck filter capacitors C1, C2, C3, C4, C5, C6, C7, and C8; the buck filter capacitors are connected in parallel, and their cathodes are connected to the reference ground GND of the main circuit; the positive output of the buck power converter circuit is DCBUCK, and the negative output is GND, which is connected to the H-bridge boost circuit.

3. The vacuum plasma excitation power supply according to claim 1, characterized in that, In the H-bridge boost circuit: the positive terminal of the input filter capacitor C43 is connected to the positive output terminal DCBUCK of the buck power converter circuit, and the negative terminal is connected to the negative output terminal GND of the buck power converter circuit; the four MOSFETs Q5, Q6, Q7, and Q8 of the H-bridge operate in an angularly symmetrical, complementary bridge arm configuration, producing a 40kHz square wave with a dead zone through chopping; the drains of Q5 and Q6 are connected to DCBUCK, and the sources of Q7 and Q8 are connected to GND; the gate of Q5 is connected to the drive signal GFB1R, and the drive signal loop EFB1 is connected to the source of Q5; the gate of Q6 is connected to the drive signal GFB3R, and the drive signal loop EFB3... The source of Q6 is connected to the gate of Q7; the gate of Q7 is connected to the drive signal GFB2R, and the drive signal circuit EFB2 is connected to the source of Q7; the gate of Q8 is connected to the drive signal GFB4R, and the drive signal circuit EFB4 is connected to the source of Q8; each of the four MOSFETs in the H-bridge has a high-voltage non-polar capacitor C40, C41, C51, and C52 connected between its drain and source; the source of Q5 is connected to the drain of Q7 to form the front bridge arm, and the source of Q6 is connected to the drain of Q8 to form the rear bridge arm; the front bridge arm is connected to pin 2 of the output terminal P19, and the rear bridge arm is connected to one end of the DC blocking capacitors C47 and C49, which are connected in parallel, and the other end of the DC blocking capacitors is connected to pin 1 of the output terminal P19; the output terminal P19 is directly connected to the primary side of the external step-up transformer.

4. The vacuum plasma excitation power supply according to claim 1, characterized in that, In the power feedback circuit: the power feedback circuit directly acquires the output voltage and current signals of the buck converter circuit in a differential form; the voltage differential signals OUTP and OUTN are respectively connected to the two terminals of the common-mode inductor L2, and then transmitted to the RC differential filter circuit composed of R69, R75, C47, and C48; the OUTN signal is filtered by the coil 1 of the common-mode inductor L2 and then connected to one end of R69, and the OUTP signal is filtered by the coil 2 of the common-mode inductor L2 and then connected to one end of R75; the differential capacitors C47 and C48 are connected in parallel, the other end of R69 is connected to one end of the differential capacitor and then to the inverting input of the precision operational amplifier U10, and the other end of R75 is connected to the other end of the differential capacitor and then to the non-inverting input of the precision operational amplifier U10; the non-inverting and inverting inputs of the precision operational amplifier U10 are connected to the signal reference ground SGND through the bleeder capacitors C51 and C50, respectively; the output of the precision operational amplifier U10 is filtered by the low-pass filter composed of R74 and C49. A voltage sampling signal VACBUS, linearly related to the output voltage, is generated. The current differential signals SGND and VIOUT are connected to the two terminals of the common-mode inductor L1, and then passed to the RC differential filter circuit composed of R64, R66, C40, and C41. The SGND signal is filtered by coil 1 of the common-mode inductor L1 and then connected to one end of R64. The VIOUT signal is filtered by coil 2 of the common-mode inductor L1 and then connected to one end of R66. Differential capacitors C40 and C41 are connected in parallel. The other end of R64 is connected to one end of the differential capacitor and then to the inverting input of the precision operational amplifier U9. The other end of R66 is connected to the other end of the differential capacitor and then to the non-inverting input of the precision operational amplifier U9. The non-inverting and inverting inputs of the precision operational amplifier U9 are connected to the signal reference ground SGND through bleeder capacitors C43 and C42, respectively. The output of the precision operational amplifier U9 generates a voltage sampling signal IACBUS, linearly related to the output voltage, through a low-pass filter composed of R65 and C39.

5. The vacuum plasma excitation power supply according to claim 1, characterized in that, In the output feedback circuit: the output feedback circuit directly acquires the AC voltage and current signals at the vacuum cavity end in the form of isolated sampling; the isolated voltage sampling signals HVSENSE+ and HVSENSE- are output through the isolation transformer and then sent to the uncontrolled rectifier bridge circuit composed of D9, D10, D13, and D14; HVSENSE+ is connected to the anode of D9 and the cathode of D13, and HVSENSE- is connected to the anode of D10 and the cathode of D14; the cathodes of D9 and D10 are connected in parallel to form the positive rectifier output, and the anodes of D13 and D14 are connected in parallel to form the negative rectifier output; the AC signal is rectified and filtered to obtain the DC feedback voltage signal, and the filter is R The DC feedback voltage is composed of C11, C41, C15, and C16 connected in parallel. After filtering, the DC feedback voltage is divided by a series voltage divider network composed of R24, R28, R30, and R34, then filtered by a two-stage series filter composed of R29, C17, R32, and C19 before being sent to the non-inverting input of operational amplifier U2.

2. The output of the operational amplifier is fed back to the inverting input via feedback resistor R22. The inverting input is divided by R25 and sent to reference ground SGND. At the output of operational amplifier U2.2, a DC voltage signal HVSENSE, linearly proportional to the voltage at the vacuum chamber load terminal, is obtained. HVSENSE is then sent to voltage comparator U after passing through a low-pass filter composed of R33 and C18. The inverting input of voltage comparator U1.2 and the non-inverting input of voltage comparator U1.2 use a fixed series voltage divider network composed of R17, R18, and R19 to obtain a fixed hardware protection threshold. The isolated current sampling signals CHF+ and CHF- are output from the Hall sensor element and then sent to the uncontrolled rectifier bridge circuit composed of D1, D2, D3, and D4. CHF+ is connected to the anode of D4 and the cathode of D2, and CHF- is connected to the anode of D3 and the cathode of D1. The cathodes of D3 and D4 are connected in parallel to form the positive rectifier output, and the anodes of D1 and D2 are connected in parallel to form the negative rectifier output. The AC signal is rectified and filtered to obtain the DC feedback current signal. The filter is composed of R6, C3, and C4 connected in parallel. The filtered DC feedback signal is filtered by a two-stage series filter consisting of R9, C6 and R10, C7, and then sent to the non-inverting input of operational amplifier U2.

1. The output of the operational amplifier is fed back to the inverting input via feedback resistor R4. The inverting input is divided by R5 to the reference ground SGND, and a DC current signal ISENSE that is linearly proportional to the current at the load end of the vacuum cavity is obtained at the output of operational amplifier U2.

1. ISENSE is then sent to the inverting input of voltage comparator U1.1 after passing through a low-pass filter consisting of R11 and C5. The non-inverting input of voltage comparator U1.1 uses a fixed series voltage divider network consisting of R1, R2, and R3 to obtain a hardware fixed protection threshold.

6. The vacuum plasma excitation power supply according to claim 1, characterized in that, In the main control circuit: the VACBUS signal is sent to the PA3 port of the main control MCU for ADC sampling, the IACBUS signal is sent to the PA2 port of the main control MCU for ADC sampling; the ISENSE signal is sent to the PA4 port of the main control MCU for ADC sampling, and the HVSENSE signal is sent to the PA5 port of the main control MCU for ADC sampling; the buck power conversion circuit and the H-bridge boost circuit are controlled in a closed loop by outputting PWM signals.

7. The vacuum plasma excitation power supply according to claim 1, characterized in that, The buck variable power circuit accepts DC input with a DC voltage range of 200-350V and a ripple requirement of less than 1%. An electrolytic capacitor with a capacitance of ≥900uF is placed after the DC power supply for buffering. The buck variable power circuit uses a dual-transistor synchronous structure with dual MOSFETs having a withstand voltage of ≥500V and a current withstand of ≥20A. The switching frequency of the buck variable power circuit is 93kHz. In the LC filter of the buck variable power circuit, the inductor L has a value of ≥1000uH, the inductor core is made of PC95 or higher material, and the capacitor C has a value of ≥1000uF and is obtained by connecting multiple small capacitors of the same capacitance in parallel.

8. The vacuum plasma excitation power supply according to claim 1, characterized in that, The switching frequency of the H-bridge boost circuit is 40kHz. During the soft-start process, the duty cycle of the H-bridge gradually increases from 5% to 49%, and the startup process takes 600ms. The four MOSFETs of the H-bridge have a withstand voltage of ≥450V and a current withstand of ≥40A. Each of the four MOSFETs is connected in parallel with a snubber capacitor with a capacitance of 1nF. The output arm of the H-bridge is equipped with a current-limiting inductor and a DC blocking capacitor. The current-limiting inductor has an inductance of ≥100uH, and the DC blocking capacitor has a capacitance of ≥100nF.

9. The vacuum plasma excitation power supply according to claim 1, characterized in that, In the voltage isolation sampling of the power feedback circuit, the precision voltage divider resistor accuracy is ≥0.1%, the isolation chip isolation withstand voltage is ≥5kV, the bandwidth is ≥275kHz, the nonlinearity is ≤±0.01%, and the signal delay is ≤1.5us; in the current isolation sampling, the Hall circuit conversion ratio is 200mV / A, the voltage isolation strength is ≥2.4kV, and the sampling bandwidth is ≥120kHz; the power feedback circuit is equipped with a common-mode inductor with an inductance of 400mH; the precision operational amplifier has a common-mode rejection ratio of ≥104dB, a bandwidth of ≥1MHz, and a gain drift of ≤1ppm / ℃.

10. The vacuum plasma excitation power supply according to claim 1, characterized in that, The main control MCU is an STM32F103VET6 with a main frequency of 72MHz. TIM3 triggers an ADC injection conversion every 25μs, with four channels sampling synchronously, and the DMA moves the results into the memory buffer. TIM1 outputs four complementary PWMs to the four MOS transistor gate drivers of the H-bridge, with a PWM frequency of 40kHz. TIM8 outputs one PWM to the Buck power conversion circuit, with a PWM frequency of 93kHz. After the ADC conversion is completed and an interrupt is triggered, the CPU calculates the current discharge power P_real = VACBUS × IACBUS, compares it with the set value P_set, and performs incremental PID calculation to update the CCR2 of TIM8 when the deviation exceeds ±1%. HVSENSE and ISENSE are compared with the safety threshold for graded limiting. The calculation time does not exceed 8μs, and power regulation and security judgment are performed within the same 25μs control cycle. Complete; When the cavity terminal voltage or current exceeds 105% but less than 110% of the rated value, the Buck duty cycle is forcibly not increased in this cycle. If it does not fall back after three consecutive control cycles, the machine will be shut down; When it exceeds 110%, CCR2 is immediately set to zero and TIM1 brake register is set. The hardware forcibly shuts down the four-channel PWM output of the H-bridge. The time from detection to brake activation is no more than 5μs; When the power deviates from the set value by more than 5% and the cavity terminal does not exceed the safety threshold, it is judged as abnormal discharge and the machine is shut down; After power-on, the ADC channel self-test is performed first. TIM1 first outputs a 5% duty cycle. Within 600ms, it is gradually pulled up to 49% to complete the soft start arc initiation. Then TIM8 outputs enable. In each control cycle, the Buck duty cycle is iteratively adjusted by the dual feedback closed-loop algorithm until P_real reaches the set value; When shutting down, the CCR2 of TIM8 is decremented in each control cycle. After the power drops below 10W, TIM8 is turned off, and then TIM1 is turned off.

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