Active Capacitor Design Based on Differential Frequency Reactive Power Theory

In view of the problems of short life and poor environmental adaptability of electrolytic capacitors, which lead to limited life of the whole machine and high system failure rate,this paper presents an active capacitor converter(ACC) which can be widely used in high power applications. On basis of that the electrical tolerance and capacity of capacitor and inductor limit the further improvement of the active capacitance capacity under the condition of fixed operating frequency, a theory of improving the operating frequency of the system and using the high frequency power to synthesize low frequency power, realizing the conversion of different frequency power and greatly improving the reactive power absorption of passive devices was proposed. Based on this theory, the topology structure of active capacitor was designed. In order to verify the performance of the active capacitor, the active capacitor is parallelled to the input port of the single-phase inverter to suppress the double frequency voltage on the DC side. The working principle of the topology is analyzed with the differential frequency reactive power theory, and the control strategy is designed to accurately control the active capacitor. The simulation platform is built, and the test results show that the active capacitor can effectively buffer the double frequency voltage pulsation.