A Comprehensive Review of Modulation-Induced Motor Losses: Assessing the Impact of Voltage Source Inverters

An accurate understanding of modulation-induced motor losses in inverter-fed traction drives is essential for optimizing inverter operation and designing high-efficiency motor drives. Yet, many prevailing studies overlook the impact of parasitic motor effects, resulting in incomplete loss models and suboptimal design decisions. This paper bridges that gap by offering both a comprehensive overview and a detailed analysis of the underlying modulation-induced loss mechanisms. Specifically, the study characterizes time-harmonic losses arising from copper, iron, and magnet components under voltage-source inverter operation. Furthermore, conventional evaluation metrics, such as the Total Harmonic Distortion (THD), are analyzed for their effectiveness in capturing time-harmonic motor losses. A novel matrix impedance measurement method is used to capture the motor’s wide-frequency response including the quantification of parasitic inter-winding and winding-to-stator capacitances. Loss-equivalent parameter fitting is employed to achieve high modeling fidelity with manageable computational demands. Incorporating parasitic effects into the overall loss model reveals a distinct switching-frequency dependency in overall system losses. This insight enables the precise determination of an optimal inverter switching frequency that minimizes modulation-induced losses, thereby enhancing the efficiency and performance of electric drive systems.