A Noninverse Internal Plant Model-Based Cascade Loop Control Structure for Compressor Drive With Small Film Capacitor

On the account of limited current controller bandwidth for small film capacitor-based compressor drive, which seriously deteriorates the reference tracking and disturbance attenuation of the inverter power loop. A noninverse internal plant model (IPM)-based cascade loop control structure is proposed, and the multiloop power-current control characteristics are fully investigated. The plant model is reconstructed, and an independent controller is induced, which decouples the disturbance issue from the reference tracking, and an extra freedom degree is provided for disturbance attenuation. The inherent drawbacks of conventional internal model controllers, such as the feasibility of the control system, high-frequency noise rejection, and robustness for model mismatches can be improved. In addition, the essence of the system instability is revealed when the compressor operates within a high-frequency range. The phase lag is precisely derived and improved with the phase-compensated resonant-type power controller. Experimental results considering grid voltage sag, background harmonics, and model mismatch are presented. The enhanced inverter power control performance and grid-side power quality can be ensured.