RESEARCH
Energy Storage Capacitor Reduction for Single Phase PWM Rectifier
Year: 2009
Fig. 1. System topology for the active ripple energy storage method.
A bidirectional buck-boost converter is connected at the output of the typical single phase PWM rectifier. An auxiliary capacitor with capacitance Cs is used as an energy storage element. We control the bidirectional converter as a buck mode when ripple energy needs to be stored in the Cs. It is controlled as a boost mode when ripple energy needs to be released back to the dc link. A dc link capacitor with capacitance Cd is still needed at the output of the PWM rectifier. Cd can be considerably smaller than the capacitance required in the conventional method, since it needs only to filter the switching ripple energy and the residual second-order harmonic ripple energy not fully absorbed by the auxiliary capacitor Cs. The switching ripple energy, results from both the PWM rectifier and the bidirectional buck boost converter.
Finally, the simulation and experimental results are shown for verification purposes.
Fig. 2. Main components volume comparison.
Fig. 3. 15kW single phase rectifier prototype.
Fig. 4. Experiment waveforms when the auxiliary circuit is active (15kW).
