# Resonant Power Supply for Plasma Cleaning Based on Fuzzy Logic Power Tracking
## 4 Analysis of Test Results
That is, the larger the phase shift angle is, the greater the influence of the phase shift angle on the output power is; otherwise, the smaller the influence is, which is consistent with the simulation results. Other factors contributing to this phenomenon are as follows: the smaller the phase shift angle is, the phase shift full bridge will gradually separate from the soft switch and become the hard switch, leading to the increase in switching loss of the power tube, thus offsetting part of the increased output power. Therefore, in order to maintain a high output efficiency, it is not advisable to adjust the phase shift angle too small in actual modulation. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Phase-Shifting Angle (\({}^{\circ}\))**} & \multicolumn{8}{c}{**Output Power (W)**} \\ \cline{2-9}  & **20 kHz** & **25 kHz** & **30 kHz** & **35 kHz** & **40 kHz** & **45 kHz** & **50 kHz** \\ \hline
10 & 958 & - & 964 & 922 & 861 & 798 & 723 \\
20  
In order to verify the PSPWM-PFM hybrid modulation algorithm, compared with the pure PWM modulation or PFM modulation, the comprehensive efficiency is higher, and the power matching accuracy is also higher. Test the resonant power supply system for plasma cleaning, respectively, input power and output power in PSPWM-PFM, PWM and PFM modulation modes, and record the relevant experimental data, as shown in Table 4.  
In Table 4, there are three groups of experimental data that are not recorded, namely: when the power is set to 500 W, the experimental data are difficult to record because the PWM algorithm fails to start the arc; when the power is set as 550 W, the experimental data cannot be recorded because of the unstable arc of the PWM algorithm; when the power is set to 1000 W, the experimental data will not be recorded because the PWM algorithm triggers over power protection. Based on the input power and output power data recorded in Table 4, you can calculate the efficiency curves of the three modulation modes at each set power, as shown in Figure 22. As can be seen from the figure, the efficiency of the PWM modulation mode is the worst among the three, and the lowest efficiency is less than 80%, especially in low power and high-power operation. This is because the PWM cannot adjust the frequency and it is easy to deviate from the resonant frequency point of the system, so that the system has too much reactive power, resulting in a low efficiency. The PFM modulation mode and the hybrid modulation mode have their own advantages and disadvantages in each set power, but at low power operation the PFM modulation mode has better efficiency than  
\begin{table} \begin{tabular}{c} **Output** \\ **Power (W)** \\ \end{tabular}  \\ \hline
500 & 573.5 & 476.6 & - & - & 681.4 & 579.9 \\
550 & 600.5 & 498.2 & - & - & 686.2 & 583  
the hybrid modulation mode because of its frequency modulation characteristics. Among them, the PFM modulation efficiency is above 85%, and the mixed modulation efficiency is above 83%, which meet the requirements. Regardless of the modulation mode, the overall efficiency of the system tends to increase as the set power increases. Similarly, according to the recorded experimental data, power matching curves of three modulation modes can be calculated under each set power. Power matching refers to the ratio between the actual output power and the users set power. The closer the value is to 100%, the higher the matching degree is, and the lower the actual output power is. The higher the actual output power is, the higher the actual output power is, as shown in Figure 23. The power matching degree of the PWM modulation mode is the best among the three. This is because the output power is most relevant to the duty cycle. The PFM modulation mode is the worst among the three, especially at low power and high power. This is because the correlation between output power and working frequency is low, and the modulation effect is not obvious. Once the equipment needs a low-power or high-power operation, it will be very difficult.