Self-Commissioning of Permanent Magnet Synchronous Machines by Considering Nonlinearities of the Voltage Source Inverter

High-performance electrical drives, typically comprised of permanent magnet synchronous motors (PMSMs), generally require correct values of electrical parameters for the tuning of controllers. Those parameters are also required for the estimation of the electromagnetic torque together with the magnetic flux linkages in the direct torque control (DTC) as well as for observers of the angular position and speed of the rotor in sensorless applications of the field-oriented control (FOC). In this paper, nonlinearities imposed by the voltage source inverter (VSI) that prevent direct measurements of electrical parameters are circumvented by a method based on quotients of secants as approximations of gradients of reference voltages and measured currents. While each measurement is performed without a position sensor at a standstill, the rotor has to be able to move to align itself with a required angular position. The novelty of the proposed method is the use of currents generated by the VSI for the alignment and the locking of the rotor. The proposed method is presented analytically and its functionality demonstrated by experiments.