Integrated inductors, capacitors, and damping in bus bars for dv/dt filter applications

A dv/dt filter is useful to mitigate the deleterious effects of voltage pulses with high edge rates, such as voltage overshoot in motor drive systems, which can cause premature motor failure. With the introduction of wide-bandgap semiconductor drives, these issues will become more pronounced. This paper introduces a new type of dv/dt filter where the inductor, capacitor, and damping resistor are integrated into the output bus bar or cable of the inverter. This integrated filter may be smaller, lighter, and cheaper to construct than filters built from discrete components. An analytical model of the integrated dv/dt filter is developed, and this model is used to design output filters for a 460 V AC, 3-phase silicon carbide motor drive that meet the NEMA MG 1 Part 31 requirements for inverter-rated motors. Prototype filters are constructed and tested with a silicon carbide inverter connected to a 460 Vrms induction motor, and experimental results demonstrate output waveforms that match the analytical model and meet the NEMA requirements.