Optimum design consideration and implementation of a parallel hybrid active power filter integrated into a three-phase capacitive diode rectifier

This paper describes the design and performance of a parallel hybrid active power filter integrated into a three-phase diode rectifier with a capacitive load. The hybrid filter is composed by a three-phase LC filter and a small rated active filter based on a three-phase voltage-source PWM converter. The passive filter is designed with focus on characteristic impedance, resonant frequency, influence on DC-bus voltage and filtering characteristics. In addition, a repetitive control algorithm with differential compensator is proposed to eliminate steady-state error in the control loop, and the design method is given in detail. The optimum design of circuit and control parameters including passive filter and repetitive controller allows the hybrid filter to minimize current THD drawn from the utility while minimizing the size and cost of the filter. The validity of the system design is confirmed by experimental results obtained from a 380 V, 20 kVA experimental prototype made in the Lab.