Stability Analysis of the Series-In Series Hybrid Active Power Filter

For the important characteristic of the system stability, a state-space averaging model of the series-in series hybrid active power filter (SHAPF) is constructed to analyze its system stability by traditional control strategy taking into account the effect of the time delay in the digital control system, inverter, low pass filter and second-order carrier-wave filter. Based on the analysis of the close-loop control model, the traditional control strategy of the series-in SHAPF is an unstable system. A new control strategy is proposed to reduce the impact of the high frequency current interference and improve its stability and filter performance of the series-in SHAPF. Validity and practicality of the proposed control strategy are proved by simulation analytical and experiment results from a 10-kW laboratory system.