Pseudorandom-Frequency Sinusoidal Injection Based Sensorless IPMSM Drives With Tolerance for System Delays

This paper proposes an enhanced system-delay-tolerant signal processing method for high-frequency (HF) signal injection based position sensorless interior permanent magnet synchronous machine (IPMSM) drives. To reduce the acoustic noises induced by the HF response current using the conventional fixed-frequency sinusoidal injection based method, the pseudorandom-frequency sinusoidal injection strategy is proposed and comparatively evaluated in terms of the power spectral density of the phase current. Furthermore, the position estimation degradation caused by the system delay effects due to the pulsewidth modulation (PWM) update delay and the hardware delay using the common signal processing method, especially with the injection frequency increasing, is analyzed. On this basis, an enhanced system-delay-tolerant signal processing strategy is proposed. Through the normalization process for the HF response current and coordinate transform, the terms related to plant parameters and system delays can be cancelled. Therefore, the reliable saliency based method with a higher injection frequency can be achieved. The comparative evaluation on a 2.2-kW position sensorless IPMSM drive is carried out, which verifies the effectiveness of the proposed scheme.