Inverter-Integrated Measurement of the Frequency-Dependent Winding Impedance of Electric Machines

Abstract:
This paper deals with resonance effects in windings of electrical machines, which can be excited by harmonic components of voltage source inverters. With increasing switching frequencies, the topic becomes more and more relevant. For standard automation drives, a method is presented that allows the frequency-dependent impedance to be measured with the inverter-integrated Σ Δ-based current measurement. The frequency-dependent impedance can be measured up to about 200 kHz, even if the PWM of the inverter switches the power transistors at a lower frequency. No additional measurement equipment is required.