Performance Comparison Between Sensor and Sensorless Control of Permanent Magnet Synchronous Motor with Wide Speed Range of Operations

Knowledge of rotor speed and rotor position is essential for effective functioning of Field-Oriented Control (FOC) technique. But this requires sensors, and thus employing advanced vector control strategies is challenging in terms of cost and reliability. In this chapter, a Sensorless Field-Oriented Control of Permanent Magnet Synchronous Motor (PMSM) covering wide speed ranges is evaluated. Maximum Torque Per Ampere (MTPA) can enhance the torque output capability, minimize the stator current and thereby copper loss and increase the overall drive efficiency. However, it is not suitable for above base speeds due to limitations on inverter ratings. Domestic appliances such as washing machine require higher speeds during spin dry cycle and usually two to three times of rated speeds. Even traction applications require a wide range of speed control. To achieve speeds greater than rated speeds, Flux Weakening is employed. Model Reference Adaptive System (MRAS) based on stator current controller is used as rotor position estimation algorithm and a comparison is performed between a controller with sensors and a sensorless controller. Results have demonstrated the effectiveness of the sensorless PMSM compared to controller with sensors for both below and above base speed operations.