Adaptive Modified Minimally Switched Hysteresis Controlled Shunt Active Power Filter for Harmonic Mitigation

The main focus of this article is to investigate the effects of Adaptive control on the switching frequency and Total Harmonic Distortion of a modified, minimally switched hysteresis controlled shunt active power filter. Reference current generation was done using Instantaneous real and reactive power algorithm. Pulses to the minimally switched grid interactive inverter in which only two switches are controlled at a time, had been generated using a modified hysteresis current controller. Use of Modified Hysteresis controller results in reducing the switching loses to one-third but results in increase in current THD than the conventional hysteresis controller. To overcome this, pulses to the modified hysteresis controller were generated employing adaptive control by modifying pulses from a conventional hysteresis controller. Using adaptive control instantaneous switching frequency was reduced and maintained nearly constant and THD was brought to the limits specified by the standards, thus overcoming the disadvantage of conventional and modified hysteresis controller which has variable switching frequency. A comparison of Modified Hysteresis controller with and without Adaptive control has been made, to show the reduction in THD. The system was simulated using MATLABSIMULINK.