A smart PWM switched power filter for single phase nonlinear loads

The paper presents a novel single smart filter and energy miser for single phase motorized and inrush type cyclical loads such as air-conditioning blowers, refrigerator and water-pumping applications. The smart filter is a tuned-arm single-phase filter equipped with a pulse width modulation (PWM) triggering circuit and a novel dynamic RMS current tracking controller. The smart filter/energy miser ensures supply power quality enhancement, less source current/load voltage waveform modulation as well as enhanced electric energy efficiency for cyclical, inrush type nonlinear motorized loads. The PWM switching scheme establishes a dynamic on-line varying duty cycle ratio α that modulates the apparent smart filter impedance to provide an effective compensating filter current level to cope with load current waveform distortion