Power factor improvement of a diode rectifier circuit by dither signals

A power factor improvement to a diode rectifier having a high-frequency inverter on the load is described. The principle of the improvement is based on dither signal effects for linearization of the nonlinear system. A diode rectifier circuit, which can be regarded as a dead-zone element, is linearized based on this principle by adding a high-frequency dither signal to the input voltage. The output voltage of the high-frequency inverter is applied to the dither, which makes the input current of the rectifier sinusoidal. The dither rectifier circuit is composed of a diode voltage-doubler rectifier and a high frequency inverter that consists of only two switching elements. Its power factor is shown to be 99.2%, and the third and fifth harmonics are 10% and 0.4%, respectively. Uses of the high-frequency inverter in fluorescent lamp and switching power supply applications are discussed.<
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