A bias power supply
By introducing a detection module and an execution module into the bias power supply system, and combining the detection of output voltage and current slope, the problem of poor arc management in existing bias power supplies is solved, and high controllability of the coating process and stability of film quality are achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- MORNSUN GUANGZHOU SCI & TECH
- Filing Date
- 2025-05-27
- Publication Date
- 2026-06-30
AI Technical Summary
Existing bias power supplies suffer from poor arc management in coating processes, resulting in poor controllability of the coating process, unstable film quality, and traditional arc extinguishing strategies that cannot accurately identify the severity of the arc, affecting workpiece damage and coating effect.
A bias power supply system consisting of a three-phase rectifier circuit, a DC-DC converter circuit, a DC/AC/DC converter circuit, and a main controller, combined with a detection module and an execution module, identifies the severity of the electric arc and performs precise arc extinguishing by detecting the output voltage and current slope.
It enables accurate identification and management of the severity of electric arcs, improves the controllability of the coating process and the quality of the coating layer, enhances the sensitivity and response speed of arc extinguishing, and reduces the risk of workpiece damage.
Smart Images
Figure CN224438829U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of solid material source ion plating technology, and in particular to a bias power supply. Background Technology
[0002] In current coating technologies, solid-state source ion plating plays a crucial role. Based on the coating technique, it can be divided into evaporation coating, evaporative ion plating, and magnetron sputtering coating. In the latter two technologies, a bias power supply provides bias conditions to the workpiece, thereby enhancing the bombardment energy of metal ions on the workpiece. This power supply plays a vital role in the coating process, including workpiece cleaning, improving film-substrate adhesion, and adjusting film color.
[0003] Because the bias power supply enhances the bombardment energy of charged ions, several other problems arise. Traditional DC bias power supplies use a constant DC output, causing metal particles to continuously bombard the workpiece. This leads to arcing of contaminants on the workpiece, easily burning the surface, and making temperature control difficult. Even though W. Olbrich in Germany proposed a pulse bias power supply in 1991, which reduced the average energy of charged ions by adjusting the duty cycle and amplitude of the output pulse, it still suffers from a series of problems with arc extinguishing strategies. Current arc detection methods generally rely on single current or voltage thresholds. However, with different duty cycles and voltages, it's currently impossible to accurately identify the severity of the arc and implement appropriate arc extinguishing measures. This results in a lack of controllability in the coating process and compromised film quality. Furthermore, if the number of workpieces increases, the arc peak value remains high during arc detection, causing damage. Utility Model Content
[0004] The technical problem to be solved by this utility model is to provide a bias power supply that can at least partially solve the arc management problem of existing bias power supplies in the background art.
[0005] To solve this problem, the present invention adopts the following technical solution:
[0006] A bias power supply is provided for providing bias voltage to a workpiece to be coated. The bias power supply includes a three-phase rectifier circuit, a DC-DC converter circuit, a DC / AC / DC converter circuit, and a main controller. The three-phase rectifier circuit, the DC-DC converter circuit, and the DC / AC / DC converter circuit are connected sequentially. The main controller is used to control the power switching transistor modules in the DC-DC converter circuit and the DC / AC / DC converter circuit to turn on and off. The DC / AC / DC converter circuit includes an arc suppression device. The main controller includes a detection module and an execution module. The detection module is used to detect the slope of the output voltage and the slope of the output current of the bias power supply. The execution module first compares the output voltage with a threshold voltage. When the output voltage is less than the threshold voltage, it then compares the slope of the output current with a threshold slope. If the slope of the output current is greater than the threshold slope and the duration reaches a set time, it is determined that the workpiece to be coated has started arcing. The execution module then controls the DC / AC / DC converter circuit to stop working and turn off the output voltage of the bias power supply, thereby cutting off the arc.
[0007] Preferably, the three-phase rectifier circuit includes a three-phase rectifier module M1, a filter capacitor C1, a filter capacitor C2, a voltage equalizing resistor R4, and a voltage equalizing resistor R5; the positive output of the three-phase rectifier module M1 is connected to the positive terminal of the filter capacitor C1, and the negative output is connected to the negative terminal of the filter capacitor C2; the negative terminal of the filter capacitor C1 is connected to the positive terminal of the filter capacitor C2; the voltage equalizing resistor R4 is connected in parallel with the filter capacitor C1; and the voltage equalizing resistor R5 is connected in parallel with the filter capacitor C2.
[0008] Preferably, the DC-DC converter circuit includes a power switch module Q1, a chopper inductor L1, an inductor current sensor HA1, an intermediate stage capacitor C3, an intermediate stage capacitor C4, a dummy load R6, and a dummy load R7. The first terminal of the power switch module Q1 is connected to the positive output of the three-phase rectifier circuit and the positive terminal of the intermediate stage capacitor C3, serving as the positive output of the DC-DC converter circuit. The second terminal of the power switch module Q1 is connected to the negative output of the three-phase rectifier circuit. The third terminal of the power switch module Q1 is connected to one end of the chopper inductor L1. The other end of the chopper inductor L1 passes through the inductor current sensor HA1 and is connected to the negative terminal of the intermediate stage capacitor C4, serving as the negative output of the DC-DC converter circuit. The positive terminal of the intermediate stage capacitor C4 is connected to the negative terminal of the intermediate stage capacitor C3. The dummy load R6 is connected in parallel across the intermediate stage capacitor C3, and the dummy load R7 is connected in parallel across the intermediate stage capacitor C4.
[0009] Preferably, the power switching module Q1 includes a first IGBT, a second IGBT, and a first diode. The drain of the first IGBT and the cathode of the first diode are connected together as the first terminal of the power switching module Q1. The source of the second IGBT is the second terminal of the power switching module Q1. The source of the first IGBT, the drain of the second IGBT, and the anode of the first diode are connected together as the third terminal of the power switching module Q1.
[0010] Preferably, the DC / AC / DC conversion circuit includes a full-bridge inverter circuit, high-frequency absorption capacitor C5, high-frequency absorption capacitor C6, DC blocking capacitor C7, high-frequency transformer TL1, high-frequency transformer TH1, gear shift contactor KL1, gear shift contactor KH1, a full-bridge rectifier circuit, an arc-suppressing inductor L2 as the arc-suppressing device, a freewheeling diode D4, and an output current sensor HA2; the full-bridge inverter circuit includes power switching transistor module Q3 and power switching transistor module Q5; the full-bridge rectifier circuit includes rectifier diodes D2, D3, D6, and D7; the high-frequency absorption capacitor C5... 5 is connected across the power switch module Q3, and the high-frequency absorption capacitor C6 is connected across the power switch module Q5; the midpoint of the bridge arm of the power switch module Q5 is simultaneously connected to one end of the primary winding of the high-frequency transformer TL1 and one end of the primary winding of the high-frequency transformer TH1; the other end of the primary winding of the high-frequency transformer TL1 and the other end of the primary winding of the high-frequency transformer TH1 are both connected to one end of the DC blocking capacitor C7; the other end of the DC blocking capacitor C7 is connected to the midpoint of the bridge arm of the power switch module Q3; one end of the secondary winding of the high-frequency transformer TL1 is connected to the rectifier diode D2 and the rectifier... The midpoint of the rectifier bridge arm formed by rectifier diode D3; the midpoint of the rectifier bridge arm formed by rectifier diodes D6 and D7 is connected to one end (2 and 6) of the normally open contact of the gear shifting contactor KL1, and the other end (1 and 5) of the normally open contact of the gear shifting contactor KL1 is connected to the other end of the secondary winding of the high-frequency transformer TL1; the other end of the secondary winding of the high-frequency transformer TL1 is connected to one end of the secondary winding of the high-frequency transformer TH1, and the other end of the secondary winding of the high-frequency transformer TH1 is connected to one end (1 and 5) of the normally open contact of the gear shifting contactor KH1. The other ends (2 and 6) of the normally open contacts are both connected to the midpoint of the rectifier bridge arm formed by the rectifier diodes D6 and D7; the anodes of the rectifier diodes D3 and D7 are both connected to one end of the arc suppression inductor L2 and the anode of the freewheeling diode D4; the cathode of the freewheeling diode D4 is connected to the other end of the arc suppression inductor L2 and passes through the output current sensor HA2 to serve as the negative output of the DC / AC / DC conversion circuit; the cathodes of the rectifier diodes D2 and D6 are connected together to serve as the positive output of the DC / AC / DC conversion circuit.
[0011] Furthermore, a filter capacitor is provided in the three-phase rectifier circuit, and a surge protection pre-charge circuit is provided before the three-phase rectifier circuit to prevent large surge current from being generated when the bias power supply is started.
[0012] Preferably, the surge protection pre-charging circuit includes a pre-charging resistor R1, a pre-charging resistor R2, a pre-charging resistor R3, and a main contactor K1; the two ends of the pre-charging resistor R1 are respectively connected to the first pair of main contacts of the main contactor K1, the two ends of the pre-charging resistor R2 are respectively connected to the second pair of main contacts of the main contactor K1, and the two ends of the pre-charging resistor R3 are respectively connected to the third pair of main contacts of the main contactor K1.
[0013] Preferably, the two control contacts of the main contactor K1 are connected to the two control signal output terminals of the main controller, and the main controller controls the coil of the main contactor K1.
[0014] Furthermore, the bias power supply also includes an auxiliary power supply circuit, which draws power from the output of the three-phase rectifier circuit and isolates and converts it to produce the auxiliary voltage required by the main controller.
[0015] Furthermore, the bias power supply also includes an interactive display screen, which can display data and enable user touch screen operation by interacting with the main controller.
[0016] The execution module in the bias power supply of this utility model first compares the output voltage with the threshold voltage. When the output voltage is less than the threshold voltage, it then compares the slope of the output current with the threshold slope. If the slope of the output current is greater than the threshold slope and the duration reaches the set time, it is determined that the workpiece being coated has started arcing. That is, the severity of the arc is identified and managed according to different operating conditions, thereby enabling accurate judgment and handling of the severity of the arc. Compared with the prior art, the beneficial effects of this utility model are as follows:
[0017] 1. Existing bias power supplies do not produce consistent arcing conditions on workpieces after operating at a given duty cycle and voltage amplitude. Arc extinguishing schemes only perform simple judgment processing based on a single parameter (output voltage) and a single threshold, without distinguishing the severity. The bias power supply of this utility model identifies and manages the severity of the arc based on the working conditions characterized by different parameters (output voltage and output current), resulting in a faster arc extinguishing response. This standard of identifying and judging different arc severity based on different parameters enables accurate judgment and handling of arc severity, thereby giving users a higher degree of control over the coating process.
[0018] 2. The arc extinguishing sensitivity of the existing bias power supply is not selectable and adjustable by the user, or the adjustment range is low, which affects the coating process and the final film effect. The main controller in the bias power supply of this utility model embodiment can adopt a digital scheme, thereby achieving high control integration, convenient operation, and a wide range of sensitivity adjustment, making it easier to meet the required process requirements. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the system structure framework of the bias power supply of this utility model;
[0020] Figure 2 This is a surge protection pre-charging circuit diagram for a bias power supply of this utility model;
[0021] Figure 3 This is a three-phase rectifier circuit diagram of a bias power supply according to this utility model;
[0022] Figure 4 This is a DC-DC converter circuit diagram of a bias power supply according to this utility model;
[0023] Figure 5 This is a DC / AC / DC conversion circuit diagram of a bias power supply according to this utility model. Detailed Implementation
[0024] To make the above-mentioned objectives, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.
[0025] It should be noted that the terms "comprising" and "having" and any variations thereof described in the specification and claims of this application are intended to cover non-exclusive inclusion. For example, including a series of components, unit circuits or control timings is not necessarily limited to those components, unit circuits or control timings that are explicitly listed, but may include components, unit circuits or control timings that are not explicitly listed or that are inherent to these circuits.
[0026] Furthermore, unless otherwise specified, the embodiments and features described in this application may be combined with each other.
[0027] It should be understood that, in the specification and claims, when an element is described as being "connected" to another element, that element may be "directly connected" to that other element or "connected" to that other element through a third element; when a step is described as being connected to another step, that step may be connected directly to that other step or connected to that other step through a third step.
[0028] See appendix Figure 1-5 As shown, the working principle and characteristics of each circuit are described below:
[0029] like Figure 1The diagram shown is a schematic of a system structure framework for the bias power supply of this utility model. The three-phase rectifier circuit, DC-DC converter circuit, DC / AC / DC converter circuit, and main controller are essential unit circuits / components of the bias power supply in this utility model embodiment. Adding a surge protection pre-charging circuit, an auxiliary power supply circuit, and an interactive display screen can further improve the performance, integration, and ease of operation of the bias power supply.
[0030] Figure 1 The bias power supply works as follows: The input is a three-phase 380V AC power supply, which is converted into high-voltage DC power by a three-phase rectifier circuit after passing through a surge protection pre-charging circuit. Subsequently, the main controller obtains the voltage level selection, output voltage, output duty cycle, arc extinguishing sensitivity, and other parameters required by the user, and then controls the DC-DC converter circuit and the DC / AC / DC converter circuit to operate, ultimately outputting the pulse voltage required by the vacuum furnace equipment load, and possessing a certain sensitivity for arc extinguishing. The auxiliary power supply circuit provides the necessary auxiliary voltage to the main controller to enable the operation of the control system.
[0031] like Figure 2 The diagram shown is a surge protection pre-charging circuit diagram for the bias power supply of this utility model. The three-phase input power passes through... Figure 2 The pre-charging resistors R1, R2, and R3 in the circuit limit the current and charge the subsequent filter capacitors C1 and C2 to prevent large inrush currents during startup. The main controller collects the voltage across the filter capacitors C1 and C2. When the main controller determines that the voltage is greater than the pre-charging completion threshold, it sends a energizing command to engage the main contactor K1, thereby reducing losses during subsequent operation.
[0032] like Figure 3 The diagram shown is a three-phase rectifier circuit diagram of a bias power supply according to this utility model. Figure 3 In the three-phase rectifier circuit shown, the three-phase rectifier bridge module M1 has a three-phase bridge structure composed of 6 diodes, which rectifies the three-phase AC power and filters it into a smoother DC power through the series filter capacitors C1 and C2. The voltage equalization resistors R4 and R5 prevent the series filter capacitors from being biased and causing overvoltage damage.
[0033] like Figure 4 The diagram shown is a DC-DC converter circuit diagram of the bias power supply of this utility model. Figure 4The DC-DC converter circuit shown consists of a step-down chopper circuit composed of dual IGBT modules Q1, chopper inductor L1, current sensor HA1, intermediate stage capacitors C3 and C4, and dummy loads R6 and R7. The gate and source of the upper IGBT module Q1 are shorted to act as a freewheeling diode. Sensor HA1 is used to collect the inductor current of the chopper output for overcurrent protection and current limiting control. Dummy loads R6 and R7 are used to maintain a constant voltage under no-load conditions. The operator inputs parameters through an interactive display interface. After the main controller obtains the required parameters, it sends an adjusted PWM wave to turn the lower IGBT module Q1 on and off, thereby obtaining the output voltage amplitude required by the operator. Its chopper switching frequency is about 40kHz, which can further reduce the size of the inductor and capacitor.
[0034] like Figure 5 The diagram shown is a DC / AC / DC converter circuit diagram of the bias power supply of this utility model. Figure 5 In the DC / AC / DC converter circuit shown, a full-bridge inverter circuit composed of power switching transistors Q3 and Q5 inverts the DC voltage output from the DC-DC converter circuit into a high-frequency AC square wave. Then, through the secondary high-frequency isolation transformers TL1 and TH1, and the gear switching contactors KL1 and KH1, the amplitude is converted to the final target voltage amplitude. Finally, it is rectified into a positive DC pulse voltage by a full-bridge rectifier circuit composed of rectifier diodes D2, D3, D6, and D7, and output to the load through the arc suppression inductor L2 and the freewheeling diode module D4. At the same time, the negative line passes through the output current sensor HA2 to collect the output current, so as to realize functions such as output overload and arc detection. In this circuit, KL1 is the low-range contactor, and KH1 is the high-range contactor. The high-frequency transformers TL1 and TH1 are connected in parallel on the primary side and in series on the secondary side. One end of the secondary winding of transformer TL1 is connected to the midpoint of the rectifier bridge arm containing D2 and D3, and the other end is connected to the midpoint of the rectifier bridge arm containing D6 and D7 through the main contacts of the low-range contactor KL1. Therefore, the main controller can control the connection of the secondary winding of high-frequency transformer TL1 by controlling the engagement of the low-range contactor KL1. Similarly, one end of the secondary winding of high-frequency transformer TH1 is connected in series with one end of the secondary winding of TL1, and the other end is connected to the midpoint of the rectifier bridge arm containing D6 and D7 through the main contacts of the high-range contactor. Therefore, the main controller can control the connection of the secondary winding of high-frequency transformer TH1 by controlling the engagement of the high-range contactor.
[0035] Figure 5The control strategy employed by the circuit is as follows: When the user requires a lower voltage range, the main controller, according to the interactive interface command, engages the low-range contactor KL1 while disengaging the high-range contactor KH1, with only the high-frequency transformer TL1 operating. When the user requires a higher voltage range output, the main controller, according to the specified command, disconnects the low-range contactor KL1 and engages the high-range contactor KH1, connecting the secondary winding of the high-frequency transformer TH1. In this case, the secondary windings of the two transformers are connected in series, thus reducing the overall transformation ratio to half and doubling the output voltage. The main controller has interlocking logic for contactors KL1 and KH1, preventing simultaneous engagement of both contactors and thus preventing abnormal output. When arcing occurs under the workpiece load, the arc-suppressing inductor L2 suppresses current, causing the arc current to rise linearly at a certain slope in the initial stage, preventing excessively rapid arc current overshoot. The freewheeling diode module D4 provides freewheeling when there is no duty cycle at output or after arc extinguishing, preventing excessively high back electromotive force from damaging other components. The main controller uses the duty cycle set by the user to send a PWM wave with a specified duty cycle to drive the power switches Q3 and Q5 of the full-bridge inverter circuit to turn on and off, so that the output terminal obtains a DC pulse voltage with the corresponding duty cycle.
[0036] The following combination Figures 1 to 5 The arc extinguishing process of the bias power supply according to the embodiment of this utility model is analyzed in detail as follows:
[0037] The main controller simultaneously detects the output voltage and output current to determine if the workpiece is arcing. When the workpiece arcs, the output voltage is rapidly pulled down due to the load characteristics resembling a short circuit. The main controller first judges the output voltage. When the output voltage is below a certain judgment threshold, the main controller then calculates and judges the current slope. Due to the current suppression effect of the arc-suppressing inductor L2, the current rise curve during workpiece arcing rises linearly with a certain slope. The main controller calculates different current rise slopes under different high and low settings. If the current slope detection value is greater than the judgment threshold and persists for a certain period of time, it is judged that the workpiece is arcing. The main controller will stop emitting PWM waveforms and turn off the power switches Q3 and Q5 of the full-bridge inverter circuit, while Q1 remains active, thereby cutting off the output voltage and extinguishing the arc. After 10ms, the inductor demagnetizes and regains its current suppression capability. The main controller will then re-emit the PWM waveform, the full-bridge inverter circuit restarts, and the output voltage recovers, thus completing a single arc extinguishing process. In specific implementation of this utility model embodiment, an arc-suppressing inductor L2 with soft saturation and high bias characteristics can be used to slow down the arc ramp-up slope, thereby effectively reducing the maximum arc-starting current within the detection time.
[0038] After completing a single arc extinguishing process, if a second arc ignition occurs, the main controller begins counting within a unit of time, recording this as the arc density. When the arc density exceeds a specified value, the power supply determines that the workpiece and power output parameter settings are incompatible. It then shuts down power switches Q3, Q5, and Q1, output contactors KH1 and KL1, and displays an alarm signal on the interactive display screen. This arc density recognition system calculates the number of arcs per unit of time. If the density exceeds the set limit, the power supply completely shuts down. This allows for early identification of unreasonable parameter settings during the initial workpiece coating process, preventing excessive workpiece heating and facilitating rapid adjustments to the coating process, resulting in better compatibility between the workpiece and parameter settings.
[0039] The above are merely embodiments of this utility model. It should be particularly noted that the above embodiments should not be regarded as limitations on this utility model. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of this utility model, and these improvements and modifications should also be regarded as protection scope of this utility model.
Claims
1. A bias power supply for providing a bias to a workpiece to be coated, the bias power supply comprising: The system comprises a three-phase rectifier circuit, a DC-DC converter circuit, a DC / AC / DC converter circuit, and a main controller; the three-phase rectifier circuit, the DC-DC converter circuit, and the DC / AC / DC converter circuit are connected sequentially; the main controller is used to control the power switching transistor modules in the DC-DC converter circuit and the DC / AC / DC converter circuit to turn on and off; characterized in that: the DC / AC / DC converter circuit includes an arc suppression device; the main controller includes a detection module and an execution module; the detection module is used to detect the slope of the output voltage and the output current of the bias power supply; the execution module is used to first compare the output voltage with a threshold voltage, and when the output voltage is less than the threshold voltage, then compare the slope of the output current with the threshold slope; if the slope of the output current is greater than the threshold slope and the duration reaches a set time, then it is determined that the workpiece being coated has started arcing, and the DC / AC / DC converter circuit is controlled to stop working and turn off the output voltage of the bias power supply, thereby cutting off the arc.
2. The bias power supply of claim 1, wherein: The three-phase rectifier circuit includes a three-phase rectifier module M1, a filter capacitor C1, a filter capacitor C2, a voltage equalizing resistor R4, and a voltage equalizing resistor R5. The positive output of the three-phase rectifier module M1 is connected to the positive terminal of the filter capacitor C1, and the negative output is connected to the negative terminal of the filter capacitor C2. The negative terminal of the filter capacitor C1 is connected to the positive terminal of the filter capacitor C2. The voltage equalizing resistor R4 is connected in parallel with the filter capacitor C1. The voltage equalizing resistor R5 is connected in parallel with the filter capacitor C2.
3. The bias power supply according to claim 1, characterized in that: The DC-DC converter circuit includes a power switch module Q1, a chopper inductor L1, an inductor current sensor HA1, intermediate stage capacitors C3 and C4, a dummy load R6, and a dummy load R7. The first terminal of the power switch module Q1 is connected to the positive output of the three-phase rectifier circuit and the positive terminal of the intermediate stage capacitor C3, serving as the positive output of the DC-DC converter circuit. The second terminal of the power switch module Q1 is connected to the negative output of the three-phase rectifier circuit. The third terminal of the power switch module Q1 is connected to one end of the chopper inductor L1. The other end of the chopper inductor L1 passes through the inductor current sensor HA1 and is connected to the negative terminal of the intermediate stage capacitor C4, serving as the negative output of the DC-DC converter circuit. The positive terminal of the intermediate stage capacitor C4 is connected to the negative terminal of the intermediate stage capacitor C3. The dummy load R6 is connected in parallel across the intermediate stage capacitor C3, and the dummy load R7 is connected in parallel across the intermediate stage capacitor C4.
4. The bias power supply according to claim 3, characterized in that: The power switching module Q1 includes a first IGBT, a second IGBT, and a first diode. The drain of the first IGBT and the cathode of the first diode are connected together as the first terminal of the power switching module Q1. The source of the second IGBT is the second terminal of the power switching module Q1. The source of the first IGBT, the drain of the second IGBT, and the anode of the first diode are connected together as the third terminal of the power switching module Q1.
5. The bias power supply according to claim 1, characterized in that: The DC / AC / DC conversion circuit includes a full-bridge inverter circuit, high-frequency absorption capacitors C5 and C6, DC blocking capacitor C7, high-frequency transformers TL1 and TH1, gear shift contactors KL1 and KH1, a full-bridge rectifier circuit, an arc-suppressing inductor L2 as the arc-suppressing device, a freewheeling diode D4, and an output current sensor HA2; the full-bridge inverter circuit includes power switch modules Q3 and Q5; the full-bridge rectifier circuit includes rectifier diodes D2, D3, D6, and D7; the high-frequency absorption capacitor C5 is connected across the power switch module Q3, and the high-frequency absorption capacitor C6 is connected across the power switch module Q5; the midpoint of the bridge arm of the power switch module Q5 is the same as... The high-frequency transformer TL1 is connected to one end of the primary winding and one end of the primary winding of the high-frequency transformer TH1. The other end of the primary windings of the high-frequency transformer TL1 and TH1 is connected to one end of the DC blocking capacitor C7. The other end of the DC blocking capacitor C7 is connected to the midpoint of the bridge arm of the power switch module Q3. One end of the secondary winding of the high-frequency transformer TL1 is connected to the midpoint of the rectifier bridge arm formed by the rectifier diodes D2 and D3. The midpoint of the rectifier bridge arm formed by the rectifier diodes D6 and D7 is connected to one end (2 and 6) of the normally open contact of the gear shifting contactor KL1. The other end (1 and 5) of the normally open contact of the gear shifting contactor KL1 is connected to the other end of the secondary winding of the high-frequency transformer TL1. The other end of the secondary winding of the high-frequency transformer TL1 is connected to one end of the secondary winding of the high-frequency transformer TH1. The other end of the secondary winding of the high-frequency transformer TH1 is connected to one end (1 and 5) of the normally open contact of the gear shifting contactor KH1. The other ends (2 and 6) of the normally open contact of the gear shifting contactor KH1 are both connected to the midpoint of the rectifier bridge arm formed by the rectifier diodes D6 and D7. The anodes of the rectifier diodes D3 and D7 are both connected to one end of the arc suppression inductor L2 and the anode of the freewheeling diode D4. The cathode of the freewheeling diode D4 is connected to the other end of the arc suppression inductor L2 and passes through the output current sensor HA2 to serve as the negative output of the DC / AC / DC conversion circuit. The cathodes of the rectifier diodes D2 and D6 are connected together to serve as the positive output of the DC / AC / DC conversion circuit.
6. The bias power supply according to claim 1, characterized in that: The three-phase rectifier circuit is equipped with a filter capacitor, and a surge protection pre-charge circuit is provided before the three-phase rectifier circuit to prevent large surge currents from being generated when the bias power supply is started.
7. The bias power supply according to claim 6, characterized in that: The surge protection pre-charging circuit includes a pre-charging resistor R1, a pre-charging resistor R2, a pre-charging resistor R3, and a main contactor K1; the two ends of the pre-charging resistor R1 are respectively connected to the first pair of main contacts of the main contactor K1, the two ends of the pre-charging resistor R2 are respectively connected to the second pair of main contacts of the main contactor K1, and the two ends of the pre-charging resistor R3 are respectively connected to the third pair of main contacts of the main contactor K1.
8. The bias power supply according to claim 7, characterized in that: The two control contacts of the main contactor K1 are connected to the two control signal output terminals of the main controller, and the main controller controls the coil of the main contactor K1.
9. The bias power supply according to claim 1, characterized in that: The bias power supply also includes an auxiliary power supply circuit, which draws power from the output of the three-phase rectifier circuit and isolates and transforms it to produce the auxiliary voltage required by the main controller.
10. The bias power supply according to claim 1, characterized in that: The bias power supply also includes an interactive display screen, which interacts with the main controller to display data and enable touch screen operation by the user.