| 摘要 |
The switching power supplies convert AC or DC input voltage into a DC output voltage. Conventional topologies are implemented, wherein power factor correction and/or square-wave switching at resonant transition is accomplished. In a front-end, rectified line voltage is applied to an inductor that attains line current. A diode limits voltage at a front-end output to a holdup voltage stored in a capacitor. A switch selectively applies the holdup voltage to the front-end output. In a DC/DC power supply, a switch selectively applies the input voltage to an inductor that attains a current. A transformer provides primary and secondary voltages in response to the current. A voltage across the inductor is limited to the primary voltage that is stored in a capacitor. The secondary voltage is rectified and applied to another capacitor that provides the DC output voltage. No output inductor is required. Furthermore, a forward power supply employs a single output diode. A transformer-less version requires a single switch. The front-end and the DC/DC power supply can be combined for a parallel operation, wherein only two switches are required. Zero voltage/current switching is accomplished. PWM can be used.
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