Error Sign Detection-Based Compensation of Commutation Error for Use in Sensorless Position Control of BLDCM

This article presents a novel commutation error closed-loop compensation method for the position sensorless brushless dc motor. A key challenge is addressed that the conventional closed-loop compensation method fails in the case of no available analog-to-digital converter (ADC). The proposed method consists of a commutation error sign detection circuit and a compensation algorithm. First, the voltage of the virtual neutral point with respect to dc-link midpoint is transformed to obtain a logic level. The logic level can indicate whether the commutation is advanced or delayed. Then, the logic level is mapped to a commutation error sign flag variable, based on which a novel iterative compensation algorithm is designed. Compared with the conventional method, the proposed method achieves a high-precision closed-loop compensation using only one general-purpose input/output of the digital processor instead of ADC. Finally, the experiments on a magnetically suspended control moment gyro prototype validate the effectiveness of the proposed method.