DC-Link Auxiliary Circuit Implementation to Improve Transient Response of Grid Connected Power Converters

Auxiliary circuits are commonly used to decouple the pulsating power from DC-link in single phase power factor correctors (PFC). Those circuits consist on a bi-directional DC-DC converter, terminated by an auxiliary capacitor. Those auxiliary modules are commonly implemented to reduce the utilized capacitance. This, in conjunction with the power factor corrector slow response, results in a large voltage drop during heavy transient. In this paper the auxiliary converter is used to improve the system response during transients even when is compared to the original system response. A mathematical expression to calculate the capacitance needed to achieve the desire response is suggested. The analytical findings are fully supported by experimental and simulations results.