A novel current control strategy in trapezoidal EMF actuators to minimize torque ripples due to phases commutations

Rectangular current fed permanent magnet actuators with trapezoidal EMF, supplied by a current controlled PWM voltage source inverter, enable to fulfil the modern large scale distribution applications with regard to cost, performances and electronics integration. However, this kind of variable speed actuator produces an important torque ripple occurring at each commutation between phases which not only depends on the EMF waveshape, but also on the current control strategy. In this paper, a novel current control strategy is presented, which enables one to minimize this ripple over the whole speed range and to improve the actuator performance. This control strategy is particularly simple to implement, because it only needs three phase current sensors and a rustic rotor position sensor. Simulations of the actuator working with this current control strategy by means of global simulation software emphasize its improvements compared to classical control strategies.