| 摘要 |
An electrical power converter system having a power factor correction circuit and a switching power converter. The power factor correction circuit converts the AC line voltage into an unregulated DC voltage referred to as the PFC voltage, which supplies an unregulated DC input voltage to the switching power converter. The switching power converter converts the unregulated DC input voltage into one or more regulated DC output voltages. The PFC voltage automatically adjusts to an appropriate value for achieving the desired power factor correction, converter efficiency, and converter temperature. In a preferred embodiment, the value of the PFC voltage is adjustable in response to a control signal produced by a PFC control circuit. The PFC control circuit measures the peak value of the input line current to determine whether the power factor is acceptable. If the power factor is acceptable, the PFC voltage will be maintained at a relatively low value. If the peak current is too high, indicating a poor power factor, the PFC control circuit will raise the value of the PFC voltage so that the power factor is improved. If excessively high temperatures occur, the PFC control circuit will lower the value of the PFC voltage so that the converter operates more efficiently and lower power losses occur. If highest efficiency operation is required under certain load conditions, the PFC control circuit will also lower the PFC voltage so that the converter operates more efficiently. |
