Dual-Phase-Shift Control Scheme With Current-Stress and Efficiency Optimization for Wireless Power Transfer Systems

Traditional wireless power transfer (WPT) systems usually adopt the single-phase-shift (SPS) control method to maintain a constant output current or a constant output voltage for various applications. However, the current-stress on one side is much higher than that of the other side especially under operating conditions with high voltage conversion ratio and light-load. This phenomenon actually can be proven by the established mathematical model of the current-stress of WPT systems using SPS control. This large current-stress will damage power devices and lower the efficiency of WPT systems. In addition, it will result in an increase of system total cost because of the need for the devices with the higher volt-ampere rating. A control strategy based on dual-phase-shift control is developed for WPT systems with an active rectifier to reduce the maximum value of current-stresses on both sides as well as to maintain a constant output voltage or current. Consequently, the system efficiency can be improved compared to traditional WPT systems with SPS control. A scaled-down experimental prototype is constructed to verify the effectiveness of the proposed WPT topology and the control method. Experimental results show that the proposed method can reduce the maximum current-stress significantly and improve the system efficiency compared to traditional WPT systems under SPS control.