Auxiliary Circuit Free Maximum Power Efficiency Tracking Scheme for Wireless Motor System With Source-Load Coupling

This article proposes a real-time maximum power efficiency tracking (MPET) scheme for a series−parallel compensated wireless motor (SP-WM) system, where the system efficiency is maximized based on real-time manipulation of the dc-link voltage. The transient performance of the motor and stability of the dc-link voltage can be improved by SP compensation with higher current overload capacity compared to the series−series one. Compared with the conventional resistive load, the motor drive can be considered as a constant power load, serving as an adjustable equivalent load resistance. The efficiency curve and resistance adjusting capability of the SP-WM system are investigated under different conditions, which demonstrate the source-load coupling between the motor drive and magnetic coupler. Besides, a dc-link voltage boundary determination (DVBD) method is proposed to ensure the safe operation of the system. The perturbation and observation and DVBD are integrated and implemented iteratively in the proposed MPET scheme. The maximum system efficiency can be achieved without an auxiliary circuit under different mutual inductance conditions, which reduces the cost and volume of the system. Finally, the feasibility and effectiveness of the proposed MPET scheme are verified by the experiments. The system efficiency can be increased by up to 4.51%.