Sensorless Control With Switching Frequency Square Wave Voltage Injection for SPMSM With Low Rotor Magnetic Anisotropy

Abstract

High-frequency signal injection sensorless algorithms are widely studied and used for rotor angle estimation in PMSM at low speed or standstill. One of the main drawbacks of such methods is the acoustic noise connected to the voltage injection. In order to minimize this problem, it is advisable to increase the frequency of the injected signal. Thus, many studies focus on square-wave injection at the switching frequency, which is the maximum theoretical frequency. Since these methods exploit the rotor magnetic anisotropy, it is relatively easy to use them in interior PMSMs, where the rotor anisotropy is high. On the contrary, it is hard to exploit them in surface PMSMs, which have an almost symmetric rotor, although a low rotor magnetic anisotropy is still present. In this paper, a sensorless algorithm with switching frequency squarewave injection is developed for surface PMSMs. To increase the signal-to-noise ratio, current oversampling is exploited. The benefits of such a technique are demonstrated with experimental results on a 2 Nm SPMSM.

Study on Sensorless Control of Six Phase Fault-tolerant Permanent Magnet Rim Driven Motor with Improved Second-order SOGI HF Voltage Injection

“…The position sensor cannot be installed due to the shaftless structure of FTPM-RDM. Sensorless control technology of DTP PMSM has been widely concerned and applied [9][10][11][12]. It is divided into two categories according to its appropriate conditions: control strategies for medium-high speed operation and for zero-low speed operation [13].…”