Fail-Safe Control Strategy of Traction Motor in Electric Mobility with Sensorless Control Scheme

A motor in electric mobility is utilized Eco-friendly vehicles for traction usually. The rotor position is critical factor in motor drive area. If the sensing of rotor position is fail due to potential faults, eco-friendly vehicles are uncontrollable by a driver. This paper proposes a novel sensorless algorithm to estimate the rotor position of interior permanent magnet synchronous motor (IPMSM). The algorithm is used to control vehicle by a fail-safe logic and it can be applied the continuous operation of vehicle, when the sensing of position is fail. This algorithm is comprised of two methods that can be applied in entire speed region. The first is the extended EMF method that uses the extended EMF model with the information of position error. The method is applied to the mid-high speed region of rotor. The second is the high-frequency injection method that estimates the rotor position using the injected high-frequency voltage signal. This method is applied to low-speed region which include zero speed, because there is no EMF or the magnitude of EMF is very small. Finally, the algorithm in this paper is utilized the two explained kinds of method and is verified by experimental results.