Investigation of Effectiveness of Sensorless Operation in Carrier-Signal-Injection-Based Sensorless-Control Methods

This paper investigates the effectiveness of sensorless operation in carrier-signal-injection-based sensorless-control methods for permanent-magnet brushless ac motors. The sensorless safety operation area (SSOA) is introduced with due account for the quantization error in the analog to digital conversion. The SSOA defines a working area in the d-q plane in which the motor can operate in sensorless mode with a guaranteed performance in steady state. With the aid of SSOA, a proper injected carrier signal can be selected for the specific prototype machine and current-measurement resolution. Experimental results confirm that the performance of sensorless operation can be guaranteed when the machine operates inside the SSOA with cross-saturation compensation.