# Research on Three-Phase Wireless Power Transfer System
## 3 Experiment and Analysis
### Simulink Simulation  
In order to verify the effect of the three-phase wireless power transfer system and adjust the parameters, a Simulink simulation model of the system is built in the Simulink environment. As shown in Figure 8 The model mainly includes a DC power supply, an inverter circuit, a three-phase coupling mechanism, and a load. The DC power supply is used to provide input power; the inverter circuit converts the DC power into a high-frequency square wave; the three-phase coupling mechanism is used to simulate the wireless power transfer; and the load simulates the electrical equipment at the receiving end. Through the Simulink simulation model, various parameters of the system can be adjusted and optimized to achieve the best wireless power transfer effect. Such a Simulink simulation environment is helpful to test and verify the system comprehensively before practical application, so as to improve the accuracy and reliability of the system design. The control pulse of the inverter module does not consider the pulse width modulation signal with a dead-time duty cycle of 50% and a frequency of 47.5 kHz. The modulation angle difference between the three phases is 120 degrees. Figure 9 illustrates the modulation pulse width signal of the three-phase inverter circuit. It can be seen that the modulation pulse width signals of the upper and lower arms of each phase are complementary, which means that when one arm is turned on, the other arm is turned off. It is to prevent equipment damage caused by a short circuit. Due to the existence of the discharge time of the switch tube, after one bridge arm is closed, it is necessary to wait for a certain time to ensure that it is fully discharged. Otherwise, when the other bridge arm is turned on, it may cause two bridge arms to be turned on at the same time, thus causing a short-circuit fault. In order to avoid this situation, we need to set a dead time so that after one bridge arm is closed, the other bridge arm is turned on after passing the dead time. This can ensure the full discharge of the switch tube and avoid the occurrence of a short-circuit fault. In this design, the dead time is set to 600 ns. This time is long enough to ensure that the switch tube is completely discharged, thus ensuring the safety and reliability of the system. At the same time, the setting of the dead time also needs to take into account the efficiency and response speed of the system. Therefore, it is necessary to shorten the dead time as much as possible under the premise of ensuring safety to improve the performance of the system. Figure 8: Simulink simulation model. In order to carry out the laboratory experiment as close as possible to the actual research situation, the electrical parameters and size of the Simulink simulation analysis are basically consistent with the laboratory experiment. For this reason, the parameters such as the value of the inductor coil and the value of the resonant capacitor used in the Simulink simulation are shown in Table 2.  
Figure 10 is the waveform of the output line voltage and current. Firstly, the voltage waveform is a square wave, and the duty cycle of the positive and negative waveforms is 1/3, which is consistent with the conduction time of the corresponding branch controlled by the control pulse. Secondly, because the coil is an inductance element in the circuit, there is a phase difference between the voltage and current. The current waveform of the circuit is sinusoidal, which indicates that the system can effectively convert the DC voltage into a stable AC current and maintain a certain voltage-current phase relationship. The three-phase input terminal works alternatively to ensure the stability and reliability of the system. In practical applications, this three-phase alternating working method can effectively balance the power load, reduce voltage fluctuations and current harmonics, and improve power quality.