Position sensorless control for interior permanent magnet synchronous motors using H∞ flux observer

Generally, a back electro-motive-force or flux observer is used for position sensorless drive of permanent magnet synchronous motors from middle to high speed range. Thus, the estimation accuracy of the observer influences position sensorless drive performance. This paper proposes a position sensorless drive system using the H_infin flux observer in which the observer gain is designed by using the H_infin control theory. This observer is insensitive to high frequency disturbances such as voltage disturbance due to nonlinearity of PWM voltage source inverter, measurement noise of current sensors, and modeling errors. The detailed configuration of the H_infin flux observer is given. Then, the performances of the proposed system are shown by computer simulations.