# Resonant Power Supply for Plasma Cleaning Based on Fuzzy Logic Power Tracking
## 4 Analysis of Test Results  
Based on the hardware circuit design and control strategy analysis in the previous sections, the prototype is developed, and the corresponding experimental platform is built. The key circuit point waveform of the prototype was tested, and the power regulation experiment was conducted to verify the relationship between the output active power, phase shift angle, and working frequency. The performance of three different modulation methods were compared and tested to verify the advantages of the hybrid modulation algorithm in the comprehensive efficiency, and the cleaning effect of the plasma cleaning machine was tested. At the same time, the influence of various factors on the cleaning effect of plasma cleaner is verified. Figure 18 shows the main circuit board of the resonant power supply system for plasma cleaning, which is designed according to the idea of modularization, including the rectifier filter circuit, the auxiliary power supply, the driving circuit, and the phase shift full bridge circuit of the front stage. The auxiliary power supply adopts a plug-in board mode, which makes full use of the longitudinal space and reduces the area of the prototype. Figure 19 shows the experimental platform of the resonant power supply system for plasma cleaning. The experimental instruments mainly include an air compressor, a four-channel oscilloscope, a programmable AC power supply, a contact angle measuring instrument, a multimeter, an ultra-high voltage probe, a differential probe, and a current probe, etc. Using a rotating jet plasma head, the discharge situation of the plasma jet during operation is shown in Figure 20.  
Figure 17: Anti-perturbation waveform when the load capacitance drops sharply. Figure 19: Experimental platform of resonant power supply system for plasma cleaning. Figure 18: Main circuit board of resonant power supply system for plasma cleaning. Figure 20: Discharge situation of plasma jet during operation. In order to verify whether the theoretical analysis and simulation of the relationship between output active power, phase shift angle, and frequency are correct, the operating frequencies of the system are set to fixed values, respectively: 20 kHz, 25 kHz, 30 kHz, 35 kHz, 40 kHz, 45 kHz, and 50 kHz. Meanwhile, the phase shift angle from 10\({}^{\circ}\) to 130\({}^{\circ}\) every 10\({}^{\circ}\) was adjusted, and the output power of the plasma prototype when working at different frequencies and phase shift angles was recorded. The test results are shown in Table 3. For data lower than 500 W, due to an unstable plasma arc, the table does not record data exceeding 1000 W are not recorded in the table because overload protection is triggered. The data in the table are sorted into curves as shown in Figure 21, and the following conclusions can be drawn from the analysis:  
1. At the same working frequency, the larger the phase shift angle of the system is, the lower the output power is; the smaller the phase shift angle of the system is, the higher the output power is. 2. The four curves of 20 kHz, 25 kHz, 30 kHz, and 35 kHz are relatively dense, that is, the resonant frequency of the system jitter in the range of 20 kHz-35 kHz. 3. At the same phase shift angle, the closer the operating frequency of the system is to the resonant frequency, the higher the output power of the system will be; otherwise, the lower the output power will be. 4. Pure PFM regulation, that is, in the fixed phase shift angle frequency modulation mode, the power range is narrow, not more than 300 W, which is the shortcoming of pure PFM modulation mode; similarly, pure PWM adjustment, that is, in the fixed frequency adjustment phase shift angle, the power range can not fully meet the requirements. 5. The curve is steeper when the phase shift angle is larger, and is slower when the phase shift angle is smaller.