Mitsujiro Sawamura

Sensorless drive of surface-mounted permanent-magnet motor by high-frequency signal injection based on magnetic saliency

This paper presents a new sensorless control scheme of a surface-mounted permanent-magnet (SMPM) motor using high-frequency voltage signal injection method based on the high-frequency impedance difference. In the SMPM motor, due to the flux of the permanent magnet, the stator core around the q-axis winding is saturated. This makes the magnetic saliency in the motor. This magnetic saliency has the information about the rotor position. The high-frequency voltage signal is injected into the motor in order to detect the magnetic saliency and estimate the rotor position. In this paper, the relationship between the high-frequency voltages and high-frequency currents is developed using the voltage equations at the high frequency, and the high-frequency impedance characteristics are analyzed experimentally under various conditions. The proposed sensorless control scheme makes it possible to drive the SMPM motor in the low-speed region including zero speed, even under heavy load conditions. The experimental results verify the performance of the proposed sensorless algorithm.

Sensorless drive of SMPM motor by high frequency signal injection

This paper represents a new sensorless control scheme of surface mounted permanent magnet (SMPM) motors. To estimate the rotor position of the SMPM motor, a high frequency voltage signal is injected and the resultant injected frequency current signal is used. In the SMPM motor, due to the flux of the permanent magnet, the stator core around the q-axis winding is saturated. This saturation effect makes some magnetic saliency of the SMPM motor. In this paper, to estimate the rotor position using this magnetic saliency, the high frequency model of the SMPM motor is developed and the high frequency impedance characteristics are analyzed experimentally under various conditions. The proposed sensorless control scheme makes it possible to drive the SMPM motor at low and zero speed operation even under heavy load conditions. The experimental results verify the performance of the proposed sensorless algorithm.

A novel hybrid speed estimator of flux observer for induction motor drives

This paper proposes a novel hybrid speed estimator that gives the synergetic effect between the model based and the saliency based field orientation for induction motor drives. The model based field orientation consists of a flux observer with an adaptive speed estimator that has unstable regions at zero frequency and zero speed. Saliency based flux orientation utilizes magnetic saliencies caused by saturation and high frequency injection that causes the torque ripples due to chattering. The chattering occurs by the higher cut-off frequency of flux angle estimation to keep the high dynamics. The proposed method compensates both faults and realizes complete speed estimation from zero to high-speed condition including zero stator frequency.

A hybrid speed estimator of flux observer for induction motor drives

This paper proposes a hybrid speed estimator that gives the synergetic effect between the model- and the saliency-based field orientations for induction motor drives. The model-based field orientation consists of a flux observer with an adaptive speed estimator that has unstable regions at zero frequency and zero speed. Saliency-based flux orientation utilizes magnetic saliencies caused by saturation and high-frequency injection that causes the torque ripples due to the chattering. The chattering is caused by the higher cutoff frequency of the flux-angle estimation to keep its high dynamics. The proposed method compensates both faults and realizes complete speed estimation from zero to high-speed condition including zero stator frequency.

High frequency injection method improved by flux observer for sensorless control of an induction motor

This paper presents a high frequency signal injection method (HFIM) improved by the flux observer for sensorless control of an induction motor. In order to reduce the chattering effect caused by the designed higher cut-off frequency of flux angle estimation to keep the high dynamics, the HFIM is combined with the flux observer, which has the filtering effect and keeps the dynamics. Furthermore, the hybrid speed estimator is proposed for smooth transition from low-speed to medium- and high-speed regions. Experimental results show that it improves the performance at ultra-low frequency including zero speed and stator frequency.