Sensorless Control for SynRM Drives Using a Pseudo-Random High-Frequency Triangular-Wave Current Signal Injection Scheme

This article proposes a pseudo-random high-frequency triangular-wave current signal injection (PR-HFTCI) based sensorless control scheme for synchronous reluctance motor (SynRM) drives at zero-low speed domain to suppress the high-frequency (HF) loss and the HF audible noise which are introduced by the significant nonlinearities of SynRMs and the traditional constant amplitude HF square-wave voltage injection method. The pseudo-random HF triangular-wave current signal with random frequency and random phase is injected to eliminate the discrete spectrum of the current power spectra density (PSD) and the corresponding current PSD analysis is performed to evaluate it. In addition, the HF component amplitude of the d-axis voltage reference can be adjusted adaptively with the variation of load to maintain the HF current amplitude constant, it is easy to implement and does not require any extra regulator and signal processing. Hence, the HF loss and the HF torque ripple can be effectively reduced under the heavy load. Finally, the effectiveness and the correctness of the proposed PR-HFTCI based sensorless control scheme are validated with experiments on a 1.5-kW SynRM drive platform.