Voltage disturbance state-filter design for precise torque-controlled interior permanent magnet synchronous motors

This paper presents the development and implementation of an online voltage disturbance estimator to achieve the precise torque control of interior permanent magnet synchronous motors (IPMSMs) over a wide operating region. Different design methodologies for disturbance extraction are analyzed using a complex vector frequency-response function (FRF) and evaluated in terms of estimation accuracy. The proposed design has a form of the state-filter based on a Luenburger-style closed-loop stator current vector observer. We provide an accurate torque control strategy with the estimated disturbance, which is based on a torque command manipulation. In addition, the developed estimator is proven to work with any torque control schemes incorporating even with numerous lookup tables. The proposed disturbance estimation scheme has the advantage of being general and readily applicable to a wide range of other systems, such as PWM converters and symmetric machines.