A Study of Charging Equivalent Inductances for Zero-Average-Torque Three-Phase-Integrated On-Board EV Chargers With Segmented Machine

For integrated on-board battery chargers (IOBCs) using permanent magnet synchronous machines (PMSMs), it is not desirable to use the winding inductance measured from the motor in a stationary state to evaluate the equivalent filter inductance during charging operation. This is because the magnetic circuit is coupled when the motor windings are reused as the grid current filters. In addition, the grid current flowing through the parameter-unoptimized PMSM makes it difficult to satisfy the charging standards, which even causes a system crash. The current of the charging system is lower compared with the propulsion mode, which means that the motor usually operates in the linear zone. On this basis, this article proposes a filter inductance model for the dynamic charging process of IOBCs. The method for evaluating the grid current ripple and current symmetry based on the inductance model is given. Then, an iterative design optimization method is used to optimize a PMSM, which enables the PMSM to balance propulsion performance and dynamic charging stability. At last, a control algorithm is proposed based on the inductance model to make the IOBCs further satisfy the charging standard. The theoretical analysis and control algorithm are verified by experiments.