Effect of dynamic magnetization manipulation on transient losses and magnet temperature in energy-saving VF-PMSM traction drives

Dynamic manipulation of magnetization state (MS) in variable flux permanent magnet synchronous machines (VF-PMSMs) during normal operation based on the torque-speed operating conditions has been shown to significantly reduce machine losses over urban driving cycles. However, the additional losses that are induced during the dynamic MS manipulation have not been evaluated. This paper presents a combination of finite element analysis (FEA) and experimental high bandwidth measurement techniques to estimate the transient losses during dynamic MS manipulation. The effect of these losses on the magnet temperature is analyzed experimentally and also by using a thermal equivalent circuit.