Efficiency and Motor-Performance Improvement Using WBG-Inverters with Observer-based Actively Damped LC-Sine Wave Filters

Abstract:
The paper demonstrates the improvement of drive system efficiency and motor performance using wide band gap semiconductor (WBG) motor inverters with sinusoidal output voltages. The presented results are based on a simple method for comparing the efficiency of different motor inverter types omitting expensive measuring equipment. Here, a WBG-inverter with an observer-based actively damped LC filter providing sinusoidal output voltages in comparison to a standard IGBT inverter with PWM output voltages are used. To avoid LC filter damping losses, the motor currents of the WBG-inverter are controlled using conventional PI-type controllers with additional feedback of the estimated filter capacitor currents gained by an adaptively tuned observer. The paper furthermore shows, that the sine-wave output inverter reduces the motor losses due to the elimination of high frequency motor currents such, that the additional switching and LC filter losses are over compensated. This results in even improved overall system efficiency despite the fact, that the acoustic noise is reduced substantially and the inver-ter-to-motor wiring is simplified by avoiding shielded cables.