Implementation of a DSP based active power filter for electric power distribution systems supplying nonlinear loads

The use of nonlinear loads, which inject undesired harmonic currents into low voltage distribution systems, is increasing rapidly. Active power filters are being considered as a potential candidate for solving harmonic problems in order to meet harmonic standards and guidelines. A new digital signal processor (DSP) based control method for a single phase active power filter (APF) is presented in this paper. Compared to conventional analog and microprocessor based methods the DSP based solution provides a flexible and cheaper method to control the APF. The proposed scheme employs a carrier based control that requires less feedback information compared to other reported solutions. Only one current sensor is used to sense the nonlinear load current and two voltage sensors to sense the input supply voltage and the DC bus voltage. It also reduces the total chip count of the system using on-chip power electronics peripherals of the DSP controller (TMS320F240). The proposed method provides both harmonic elimination and power factor correction. The PSpice simulation and experiments using the DSP controller are made to verify the feasibility of the method.