Adaptive Signal Injection Method Combined with EEMF-based Position Sensorless Control of IPMSM Drives

Abstract

This paper deals with an amplitude-adjusting method for signal injection in position sensorless control of interior permanent magnet synchronous motor (IPMSM) drives. Signal injection is necessary for position estimation at standstill and low speeds. Response signals to the injected signals have position information because of the saliency of the IPMSMs. The position information appears in inductances depending on the rotor positions; therefore, time derivative of motor currents has to be measured directly or indirectly. The position estimation method discussed in this paper is based on an extended electromotive force (EEMF) model. Although the EEMF model is mainly used in middleand high-speed regions of IPMSM drives, it can be applied to all speed regions by combining it with signal injection methods. We adopt a signal injection method to stabilize the estimation and reduce the effects of disturbances. Then, the amplitude of the signal currents is adjusted to maintain a sufficiently high amplitude of EEMF against disturbances. Signal setting becomes easier because the lower limit of EEMF can be adjusted against the degree of disturbances.

Evaluation Method to Estimate Position Control Error in Position Sensorless Control Based on Pattern Matching Method

“…Many sensorless techniques for IPMSMs have been proposed (1)- (8) . In medium and high-speed regions, a commonly used method is based on the extended electromotive force (EEMF), which is generated proportional to the rotor speed (1) (2) .…”

“…In medium and high-speed regions, a commonly used method is based on the extended electromotive force (EEMF), which is generated proportional to the rotor speed (1) (2) . At a standstill and in very-low-speed regions, a method using the angle dependency of the inductance spatial distribution is generally utilized (3)- (8) . In Refs.…”

“…In addition, a method using both an observer of the EEMF and signal injection was proposed in Ref. (8).…”

Position Sensorless Control for IPMSM of Spatial Inductance Distribution with Nonsinusoidal Inductance Waveform Based on Pattern Matching Method

“…Conventionally, position sensorless control at stop or low speed is based on sinusoidal spatial distribution of phase inductances with double period of electrical angle [3][4][5][6][7][8]. Conventionally, position sensorless control at stop or low speed is based on sinusoidal spatial distribution of phase inductances with double period of electrical angle [3][4][5][6][7][8].…”

“…Conventionally, position sensorless control at stop or low speed is based on sinusoidal spatial distribution of phase inductances with double period of electrical angle [3][4][5][6][7][8]. Particularly, signals are injected in estimation coordinates, and position is estimated from the magnitude of response current (correlation signal) [3][4][5][6][7]; in another method, extended EMF observer is combined with signal superposition [8]. These methods assume sinusoidal distribution of phase inductances; in motors with nonsinusoidal distribution, errors occur in position estimation, thus impairing the performance of position sensorless control.…”