Analysis of Impedance Tuning Control and Synchronous Switching Technique for a Semibridgeless Active Rectifier in Inductive Power Transfer Systems for Electric Vehicles

In inductive power transfer (IPT) systems, load, and magnetic coupling variations cause an impedance mismatch. Impedance mismatch is one of the most serious problems in IPT systems for electric vehicles (EVs) because an EV is not always parked in the same location. Therefore, an impedance tuning control for semibridgeless active rectifiers (SBARs) is proposed in this article to compensate for this mismatch. The proposed impedance tuning control is achieved by adjusting the turn-on point and duty of the SBAR without using any additional component. Moreover, a technique for detecting the voltage-rising edge of the SBAR switch is proposed to extract the switching frequency and to synchronize the SBAR with the primary system. A 3.3-kW prototype of the IPT system with the SBAR is manufactured, and the proposed impedance tuning control is verified through experimental results according to the coupling coefficient. The proposed control can achieve an efficiency improvement of 6.4% under the impedance mismatch.