Output Power Regulation of a Series-Series Inductive Power Transfer System Based on Hybrid Voltage and Frequency Tuning Method for Electric Vehicle Charging

In the inductive charging scenario of an electric vehicle (EV), the charger should have the capability to flexibly regulate the output power regardless of the misalignment and EV battery voltage. This article proposes a hybrid voltage and frequency tuning strategy for a series-series (SS) inductive power transfer (IPT) system to regulate power through 0 to 3.3 kW at any battery voltages and misalignment conditions without using additional converters. A voltage tuning is used to achieve full-power of 3.3 kW and partly contribute to reducing the power. When the input voltage achieves the lower limit, a frequency tuning is used to further decrease the power to 0 W, achieving the regulation through 0 to full power. The practical charging region is specified by 110 mm airgap, 100 mm misalignment in both x and y directions, and 180-240 V battery voltage range. Experiments are carried out at various conditions, and it shows that with an input voltage range of 180-380 V and a frequency of 82.5-87.9 kHz, the charging power can be regulated between 100 W and 3.3 kW at any case in the specified working region. In addition, a peak dc-dc efficiency of 95.7% is achieved at 3.29 kW.