Simple position sensorless V/f scalar control method for permanent-magnet synchronous motor drives

When permanent magnet synchronous motors (PMSM) are used in pump and fan applications where no excessive performance is required, the V/f scalar control method can be applied to enhance the ease of use for end users. For the voltage reference generation in V/f control, existing methods requires motor parameters such as the stator resistance, inductance, and back EMF constant of the permanent magnet, which is identified before or during operation. However, this paper proposes a simple and convenient V/f control method that utilizes the motor parameters given on the name plate. In the proposed method, stable operations are ensured for the rated speed and load ranges without position sensors. For successful starting operation, a DC current control loop is included to calculate the initial offset voltage reference for the V/f pattern. The stability and effectiveness of the proposed method are analyzed and verified by MATLAB/Simulink and 3.7 kW IPM motor drive experiments.