Analysis of the electromagnetic torque and the effective winding inductance of a surface-mounted PMSM under integrated battery charging operation

The concept of integrated battery charger is attracting attentions these days. To design a motor drive system with an integrated charging capability, the machine windings are usually reconfigured to be used as the AC side inductors. Along with the switches from the drive circuitry, the AC side inductors form the voltage front-end to improve the power factor while charging. Most of the research work that was conducted was focused on the circuit topologies [1], [2] and the charger performances [3]. When looking into the basis, what will happen inside the machine when AC current is flowing through the machine windings? More specifically, the interactions between the electromagnetic field produced by the AC current excitation and the rotor magnetic field can cause electromagnetic torque and variations of the effective winding inductance. In this investigation, these two aspects, the produced torque and the impedance due to different winding configurations under a single-phase integrated charging operation employing a surface-mounted permanent magnet synchronous machine (SPMSM) drive system are analyzed. Experimental tests were conducted on a 21 HP, 8-pole SPMSM to verify the results.