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This paper proposes an improved pulse density modulation (PDM) control for a semi active rectifier (SAR) in wireless power transfer (WPT) with LC/S compensation. In order to improve the output regulation performance of the WPT converter, an improved pulse density modulation (PDM) is used, and its control signals are applied to the switches of the SAR. Based on the improved PDM control, the pulse sequence of the SAR is distributed more evenly compared to the traditional PDM. Thus, the output voltage ripple of the WPT converter is decreased and the output current ripple of the high frequency inverter (HFI) is decreased as well. The soft switching conditions can be achieved for both the SAR and HFI switches. In addition, since the control is applied only to the receiving side, there is no necessary for the communication devices. A simulation study is carried out to verify the performance of the improved PDM control and compared with the traditional PDM control. Based on the simulation results, the ripples of the output voltage as well as the output current ripples of the HFI are effectively reduced by using the improved PDM. Finally, the experimental results are presented to validate the effectiveness of the proposed control method. |
