Design and control system of inverter-driven permanent magnet synchronous motors for high torque operation

This work describes a current vector control method for permanent magnet (PM) synchronous motors suitable for high-torque operation. The current phase angle is controlled according to load conditions in order to use the reluctance torque effectively. Characteristics such as torque, efficiency, power capability and so on are greatly improved by this control method in comparison with the conventional control method. The performance characteristics are greatly affected by the motor parameters, which depend on the rotor configurations and permanent magnet geometries. The available maximum torque and power capability are also examined for the several types of PM motor, taking into consideration the inverter capacity. The tendency toward magnetic saturation and demagnetization of the permanent magnet is also examined