Transducerless Acquisition of the Rotor Position for Predictive Torque Controlled PM Synchronous Machines Based on a DSP-FPGA Digital System

In this paper, a wide-speed-range predictive direct torque control scheme for surface-mounted permanent magnet synchronous machines without rotational transducer is presented. At very low and zero speeds of operation, the identification of the rotor position is carried out by applying test voltage signals within the regular commutation process for predictive torque control, in order to detect the machine saliency produced by the stator magnetic saturation. Then, the acquired signals that are function of the rotor position are digitally processed through a quadrature phase-locked loop tracking observer. At middle-and-high speeds of operation the angular position of the rotor is estimated by using a predictive sliding-mode observer of the stator flux. A changeover algorithm is programmed for coupling both estimated values of the angular position of the rotor. Experimental results in a wide-speed-range obtained by using a hybrid digital system which consist of a digital signal processor (DSP) and of a field-programmable gate array (FPGA) verify the effectiveness of the proposed encoderless predictive control scheme.