# Resonant Power Supply for Plasma Cleaning Based on Fuzzy Logic Power Tracking
## 2 Plasma Cleaning Power Supply Design  
The nozzle of the plasma cleaning machine produces plasma by the electrical breakdown of gas. For the plasma resonant power supply, the plasma torch is equivalent to a large capacitive load. If the pre-stage power supply is not properly compensated, the power factor will be too low affecting the efficiency, and the quality factor of the system will not be well controlled, while a small quality factor will cause a poor selectivity of the output power in frequency modulation [5]. Compensation for the capacitive load can be achieved by adding inductance to the primary side to form series resonance. In the case of a non-uniform electric field, the breakdown of 1 mm of compressed air needed for the breakdown voltage of about 3 kV, causes a lot of leakage inductance in the transformer. Now that the leakage inductance of the transformer is inevitable, simply using the series resonance with the load capacitance, can play a role of power factor compensation, and have a good quality factor. At the same time, it also avoids the volume increase caused by additional inductance. The full-bridge inverter circuit is generally used to form high frequency and high voltage with a positive and negative polarity on the plasma torch. Although the traditional non-phase shifting control is simple, it is not convenient to construct a soft switch, and the switching loss is large. By adopting a phase shift full bridge control mode, the soft switch can be easily constructed, and the efficiency can be improved. Therefore, the phase-shifting full bridge is adopted as the control mode of the main circuit in this system [6]. The system architecture of the resonant power supply for plasma cleaning is shown in Figure 1, which mainly includes four parts: the power module, the control module, the auxiliary power module, and the human-computer interaction module. The power module includes the front rectifier filter module, the phase shift full bridge circuit, and the high-frequency resonant transformer. The rectifier filter module is responsible for the power grid 220 V AC through the diode rectifier bridge and filter circuit to get smooth DC. The phase-shifting full-bridge circuit is responsible for inverting the DC obtained in the previous stage into a high-frequency AC square wave, acting on the high-frequency resonant transformer [7]. The high-frequency resonant transformer boosts the low-voltage AC square wave of the primary winding to the high-voltage AC square wave of more than 3000 volts of the secondary winding, and acts on the load discharge gun head, so that the gas of the gun head is continuously decomposed and generates plasma, which acts on the cleaning object. The control module consists of signal detection and the conditioning circuit, the main control STM32 chip, and the phase shift full bridge driver circuit. The signal detection circuit is responsible for obtaining circuit voltage, current, and temperature information, and these analog signals through the conditioning circuit modulation output to the master chip. The master chip converts these analog signals into digital signals in the program and calculates them to obtain the working condition of the plasma cleaning power supply system and controls the corresponding driving circuit accordingly to ensure the safe and stable work of the system. The auxiliary power module is a multi-output quasi-resonant flyback circuit with UCC28610 as the control core, which supplies power to the circuits of different voltage levels such as the master chip, the signal conditioning circuit, and the drive circuit. The human-computer interaction module is responsible for real-time communication with the main control chip to obtain the operation information of the plasma cleaning power supply system and display it through the control panel. Users can understand the real-time working conditions of the system through the panel and set the operation parameters through the operation control panel.