Current Balancing of a Multiphase Inverter for LCC-S Compensated Wireless Power Transfer System Based on Mutually Negatively Coupled Inductors

To enhance the output power level of wireless charging applications, multiphase inverters are usually required to work in parallel. Even though the same pulsewidth modulated signals are applied for the corresponding switches, there can still be phase differences in the driving pulses, which directly turn on/off the switches, due to the inconsistency in the switch parameters or driving circuits. The different driving pulses can result in large circulating currents, which decrease the power level. There is a need for a current balancing technique that can be used to solve this problem. This letter proposes a passive current balancing method for wireless charging. Compared with the existing method, the proposed method can reduce the number of coupled inductors by half and balance every two sources to achieve good current balancing performance. An inductor-capacitor-capacitor series compensated wireless power transfer experimental prototype is built to validate the effectiveness of the proposed current sharing method.