Sensorless drive of brushless DC motors with estimating torque constant for home appliance

A new sensorless control algorithm of BLDCM(Brushless Direct Current Motor) is proposed. The estimated torque constant of motors is ideally constant, but it begins to decrease at commutation point(CP) because the back EMF drops at this point. Therefore, CP can be detected for the sensorless control of BLDCM by estimating torque constant. The proposed control algorithm is simple, robust to the parameter errors and doesn´t require additional hardware compare to the conventional algorithms. The experimental results are shown to verify the usefulness of the proposed control algorithm.