Abstract
The instantaneous output power of the two-stage inverter pulsates at twice the output frequency, resulting in the second harmonic current (SHC) in the front-end dc-dc converter. To reduce the SHC in the inductance branch while maintaining good dynamic performance, this paper proposes a control scheme based on a new inductor current feedback path in the front-end buck converter. In the scheme, through the equivalent gain, the virtual resistor, and the bandpass filter, the inductor current is fed to the front of the voltage regulator. The feedback function simplification is studied and the implementation of the proposed scheme is illustrated. With considerations of both reducing the SHC and improving the dynamic performance, the parameter design approach for the feedback function is also presented for the proposed SHC reduction control scheme, and the performance analysis and comparison from the viewpoint of output impedance are provided. The simulation model and the prototype of a 10 kW two-stage inverter are constructed. The simulation and experimental results about the low SHC in the front-end buck converter and the fast dynamic response during the load transient verify the effectiveness of the proposed scheme.