Enhanced i/f control system and method for permanent magnet synchronous machines

Abstract

A method of operating a motor drive includes injecting a high frequency signal to determine position error information in order to automatically adjust the magnitude of stator current in I/F control. The method includes: determining a load-based q-axis current corresponding to a load of an electric machine; determining an adjusted q-axis reference current based on the load-based q-axis current; determining d, q-axis reference voltages based on corresponding d-axis and q-axis reference currents; determining α,β-axis reference voltages based on the d, q-axis reference voltages and a reference rotor position; commanding an inverter based on the α,β-axis reference voltages; increasing the reference rotor angular frequency while the d-axis reference current is zero and while the q-axis reference current is maintained at a constant value; adding an injection voltage signal to the d-axis reference voltage, and using a sum of the injection voltage signal and the d-axis reference voltage to determine the α,β-axis voltages.