Design and fully digital control of parallel active filters for thyristor rectifiers to comply with IEC-1000-3-2 standards

This paper presents the implementation of a digitally controlled parallel active filter for a thyristor rectifier with inductive load. Using a state-of-the-art digital signal processor (DSP) platform (ADSP21020 and ADMC200), a fully digital control of the system, based on the dead-beat control of inverter currents and space vector modulation, is implemented. The intrinsic calculation delay of the dead-beat algorithm is shown to represent a serious hurdle for the achievement of a satisfactory compensation quality. In particular, meeting the IEC 1000-3-2 standards for class A equipment appears to be quite difficult, especially in the high-frequency range. This paper investigates the effects of the input passive filters and power converter design on the system's performance and describes the implementation of the digital control by means of the specified hardware. Experimental results are finally given to evaluate the achieved performance.