Inverter non-linearity effects on a sensorless PMSM drive without additional test signal injection and zero speed operation

Abstract

It has been well established in the literature that inverter non–linearity effects afflict saliency based sensorless drives operating in the low and zero speed region. The inverter non–linearity leads to the generation of signals that corrupt the useful position signals. In certain cases, the magnitude of the former signals is comparable if not higher to the latter. Various compensation techniques to overcome this effect have been published in the literature. This paper is concerned with the sensorless technique utilizing the current derivatives during the zero voltage vector states without additional test signal injection, as proposed in [1]. This paper incorporates the varying on–state resistance of the inverter power devices in the system model to explain the corrupting signal experienced in [1]. Knowledge of the source of the corrupting signals facilitates compensation and determines its applicability. The same effect will also be present in sensorless techniques utilizing signal injection although its influence might be less significant due to the magnitude of the injected signal.