An Improved Pulse Density Modulation Control for Secondary Side Controlled Wireless Power Transfer System Using LCC-S Compensation

In this article, an improved pulse density modulation (PDM) control for secondary side controlled wireless power transfer (WPT) system is proposed. The LCC-S network is selected for the compensation of the reactive power in the system. In the secondary side, an active rectifier with improved PDM control is used to regulate the output voltage. The output voltage regulation is achieved by changing the pulse density of the rectifier switches. By using the proposed PDM pattern, the input pulse sequence of the active rectifier can be distributed more homogenously compared to the conventional PDM control. Therefore, the output current ripple of the primary side inverter and the output voltage ripple of the active rectifier are reduced. The light load efficiency is also improved compared to conventional PDM control. The soft switching conditions are achieved for inverter and active rectifier switches. The experimental prototype with 150 mm air gap is built to validate the performance of the proposed system. The overall efficiency of the system with the proposed PDM is improved by 1.7% and 9.9% compared to the conventional irregular and regular PDM control, respectively. The output voltage ripple of the active rectifier and the output current ripple of the primary inverter are also reduced at light load conditions with the proposed PDM.