| 摘要 |
A boost type power supply circuit for providing a DC output voltage comprising first and second semiconductor switches coupled between respective input lines and a common connection; an AC input voltage from an AC source being supplied across the input lines; first and second diodes coupled in series with respective ones of the switches; third and fourth diodes coupled across respective ones of the switches in a free-wheeling relationship with the switches; an inductance coupled in at least one of the input lines; a controller for controlling the conduction times of the switches by providing a pulse width control signal to each of the switches; wherein the controller turns on at least one of the switches during a positive half cycle of the AC voltage to allow energy storage in the inductance and turns off the at least one switch to allow the energy stored in the inductance to be supplied to an attached load through one of the first and second diodes and one of the third or fourth diodes; and the controller turns on at least one of the switches during a negative half cycle of the AC voltage to allow energy storage in the inductance and turns off at least one switch to allow the energy stored in the inductance to be supplied to the attached load through one of the first and second diodes and one of the third and fourth diodes. The controller determines an on-time and an off-time of a pulse of the pulse width modulated control signal during each half cycle of the AC voltage, the on-time and off-time of the pulse being controlled to regulate said output voltage and to provide power factor correction of said AC input voltage, based on either voltage sensing or current sensing.
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