Active Capacitors With Ripple Cancellation Control for AC-DC Converter Applications

Active capacitors with long lifetime film capacitors can be adopted to replace short lifetime electrolytic capacitors to improve the reliability of the power converter. However, the conventional active capacitor suffers from the complicated control method or the need for an expensive current sensor. Based on the derived mathematical equations, a novel Ripple Cancellation Control (RCC) method for the active capacitor is proposed. The proposed RCC method is simple and can be easily realized by using analog circuits. Also, it can be applied to active capacitors implemented by different circuit topologies. Besides, a new approach for developing the mathematical model of the active capacitors implemented by different circuit topologies are also proposed. The energy storage capability and the impedance analysis by using the developed mathematical model are presented to verify the performance of the active capacitors with the proposed RCC method. Computer simulations and the hardware results are presented to validate the accuracy of the mathematical model as well as the performance of the proposed RCC method.