Design and evaluation of an active ripple filter using voltage injection

Active ripple filters can affect substantial reductions in power converter input and output ripple components, allowing considerable reduction in passive component size. This paper investigates a hybrid passive/active filter topology that achieves ripple reduction by injecting a compensating voltage ripple across a series filter element. Both ripple feedforward and feedback are employed. The design of sensor, amplifier, and injector circuitry suitable for the application are investigated. The experimental results demonstrate the feasibility and high performance of the new approach, and illustrate its potential benefits. It is demonstrated that the proposed approach is most effective in cases where it is desirable to minimize the amount of capacitance in the filter