Patent ID: 7301787

Claim:
An active type harmonic suppression apparatus comprising: a dc power capacitor providing a regulated dc voltage; a power converter including a power electronic device set, the power converter electrically connected with the dc capacitor, and being switched for generating a compensation voltage; a filter inductor electrically connected with the power converter for filtering a ripple current generated from switching the power converter; a reactive power compensation capacitor connected in series with the filter inductor for acting as a reactive power generator, the reactive power compensation capacitor lowering the dc voltage of the power converter; a combined capacitor/resistor filtering set electrically connected between the reactive power compensation capacitor and a power line of a power source such that the combined capacitor/resistor filtering set is used for further filtering ripple current generated from switching the power converter; and a control circuit for calculating a reference signal for the compensation voltage, and controlling the power electronic device set of the power converter, said control circuit using a load current, a utility current, an output current of the power converter, a voltage of the dc power capacitor and a power source voltage to calculate said reference signal for controlling the power converter; wherein the filter inductor, the reactive power compensation capacitor and the combined capacitor/resistor filtering set converts the compensation voltage into a compensation current for injecting into a power feeder, and thereby a utility current supplied from a power source is approximated as a sinusoidal waveform such that the active type harmonic suppression apparatus is provided with a fixed reactive power.