Signal-injection-based sensorless IPM traction drive for wide-torque range operation at low speed

Generally, the sensorless control technique based on the high-frequency voltage signal injection method is used to detect the rotor position of an interior permanent magnet synchronous motor (IPMSM) at the low-speed region. However, this technique does not work well at heavy load conditions, because the rotor incremental saliency decreases due to magnetic saturation. Here we present a high-frequency signal injection-based sensorless control approach, which is applicable over a wide range of torques. The proposed approach makes use of beneficial inductance phenomena appearing in the IPMSM under heavy load operations. The results of our experiments using a 36 kW-350 Nm IPMSM show that the proposed sensorless drive meets the requirements for the target HEV application.