Topology Optimization of the IPMSMs Considering Both the MTPA and FW Controls Under the Voltage and Current Limitations

Abstract

This study proposes a novel topology optimization which can maximize the average torque of the interior permanent magnet synchronous motors (IPMSMs) in both the maximum torque per ampere (MTPA) and field weakening (FW) regions. In principle, the back electromotive force (EMF), which is proportional to a rotating speed, should be suppressed below the DC-link voltage to protect a power supply system. However, because the design and current reference of the IPMSM are coupled to affect the back EMF, it has been challenging to simultaneously determine the optimal design and current reference under such a voltage limitation. To solve the above issue, this study derives the design-dependent FW current reference in terms of the elementwise relative densities, which are set as design variables in topology optimization. In addition, the selection criterion between the MTPA and FW operations is proposed under the same design parametrization. After estimating the motor-design parameters, the proposed method simultaneously determines the optimal design and the corresponding current reference in both the MTPA and FW regions. The simulation and experimental results clearly demonstrate the validity of the proposed method.