Improved Pulsating Signal Injection Using Zero-Sequence Carrier Voltage for Sensorless Control of Dual Three-Phase PMSM

The sensorless control performance of pulsating carrier signal injection employing zero-sequence voltage for dual three-phase (DTP) permanent magnet synchronous machine (PMSM) drives is investigated in this paper. This method has the synergy of high bandwidth of zero-sequence voltage method and high position estimation accuracy of pulsating injection strategy. However, such a method for single three-phase PMSM exhibits large oscillation in position estimation error due to undesirable harmonic components in the zero-sequence carrier voltage, and the existing compensation methods usually require complex structures or intensive offline measurements. As for DTP-PMSM, the undesirable harmonic components for the pulsating injection can be suppressed with an optimum phase shift between the two injected high-frequency signals. Besides, a new simple measurement method of zero-sequence carrier voltage is proposed with only one voltage sensor placed between the two isolated neutral points. As a result, the rotor position estimation accuracy can be significantly improved. The experimental results verify the effectiveness of the proposed method for DTP-PMSM.