Position estimator for a brushless-DC machine using core saturation and stator current slopes. http://dx.doi.org/10.1108/03321641211184896

Abstract

This paper describes how to estimate the rotor position of a Brushless DC (BLDC) motor. Two different strategies, both based on sator currents, will be used: one for low speeds to start the ICE, and one for normal speeds for future applications in a pure electric vehicle (EV). The first one uses an estimation method based on core saturation and the second one is based on the determination of the current slopes on two of the three phases. The algorithms proposed neither needs to measure any machine parameters, nor the back emf. The methods use the information contained in the current magnitudes and slopes, and the machine mechanical speed. The system was implemented using a Digital Signal Processor (TMS320F241), which controls the phase currents and makes all the calculations required for position estimation. Additionally, the PWM signals are transmitted through a fiber optic link to minimize noise production and error on commutations.