A comparison between V/f control and position-sensorless vector control for the permanent magnet synchronous motor

This paper presents a comparison between V/f control and position-sensorless vector control for the permanent magnet synchronous motor (PMSM). At first, it describes the PMSM V/f control method, which consists of the stabilization and the high efficiency control. In addition, it describes the sensorless vector control method, which consists of the high and middle speed range algorithm and the low speed range algorithms. The V/f control, which realizes a low cost and simple design, is advantageous in the middle to high-speed range. Its torque response depends on the electrical time constant of the motor and adjustments of the control parameters are not needed (as in case of sensorless vector control). The sensorless vector control performs very well in the low speed range including the zero speed. However, it requires a high-speed position estimator to constrain the current regulator and the speed regulator design. The V/f control is the best choice for simple variable speed applications like fans, pumps and it is more effective in the high-speed range. The sensorless control is the best choice for simple tension and low speed control applications like cranes and high performance drives