A Measurement Method for Iron Loss Resistance Considering Nonlinear Voltage Error of Inverter

Iron loss resistance is a key parameter for motor modeling and control. Accurate iron loss resistance plays an important role in the efficient control of motors. To improve the measurement accuracy of iron loss resistance of permanent magnet synchronous motor (PMSM), this paper proposes a new iron loss resistance measurement method that considers the nonlinear error of the inverter. Firstly, considering the nonlinear voltage error of the inverter caused by the parasitic capacitance, the dead time, the turn-on and turn-off delay of switching devices, and the conduction voltage drops of switching devices and diodes, the nonlinear voltage error of the inverter is evaluated and compensated through numerical fitting. Secondly, based on the linear relations between the loss which is obtained by subtracting motor copper loss from input power and square of back electromotive force (EMF), the iron loss resistance is calculated offline from the slope of this linear function. The proposed method directly calculates the iron loss resistance without requiring any measurements related to mechanical losses, and it can be performed under any load conditions. Finally, the effectiveness of the method was verified through experiments.