High performance low cost control of a permanent magnet wheel motor using a hall effect position sensor

In more electric vehicles, to reduce cost, volume and weight, a Hall effect position sensor may be used instead of a resolver as the mechanical sensor to allow vector control of a Permanent Magnet Synchronous Machine (PMSM) with a sinusoidal back-EMF. As this kind of sensor provides only six measurements per electrical turn, the position error between the actual rotor position and the measured position can reach 30 electrical degrees. Such an error affects deeply the control performances and causes important torque oscillations and over-currents which are not acceptable in applications like transportation systems. This paper presents a simple algorithm that combines the measurements of Hall Effect sensor with a “sensorless” method which estimates position and speed between two measurements. The efficiency of the proposed algorithm has been verified on a four poles 2 kW 1500 rpm test machine.