An Improved Active Damping Strategy based on DOB for SiC-based Motor Drives with Sinusoidal LC Filter

Wide-bandgap power devices represented by silicon carbide (SiC) have the advantages of high resistance voltage, fast switching process, and strong high-temperature resistance. But the fast switching process will generate very large dv/dt and di/dt, which poses a major threat to the stable operation of the motor drive system. In general, the introduction of a sinusoidal LC filter can effectively solve the problem of excessive voltage and current stress. But lower cutoff frequencies can also cause the system to resonate. In this paper, a disturbance observer (DOB) based resonance suppression strategy is proposed. The capacitor voltage can be observed by sampling the inverter side current. The observed voltage is superimposed on the current loop output. In this way, the resonance of the system can be effectively suppressed. Experimental results demonstrate the effectiveness of the proposed method.