| 摘要 |
PROBLEM TO BE SOLVED: To improve a power factor by a method wherein switching devices which are operated in a positive side half cycle period and in a negative side half cycle period are combined to compose a switching circuit. SOLUTION: If driving signals are supplied to switching devices 12 and 13 when a commercial power supply voltage is in a positive side half cycle period, an operation current route is as follows: A commercial power supply 1 and a capacitor 3→a reactor 4→a switching device 12→from the source to drain of a switching device 13 and the parasitic diode 13' of the switching device 13→the commercial power supply 1 and the capacitor 3. An energy is stored in the reactor 4. Then, if the driving signals are turned off, the energy stored in the reactor 4 is discharged through a route as follows: The reactor 4→a diode 14→a capacitor 7→the parasitic diode 13' of the switching device 13→the capacitor 3→the reactor 4. Thus, the capacitor 7 is charged by the energy and a stable DC voltage can be supplied to a load 0. Further, in the negative side half cycle period, the same procedure is repeated. As a result, a power factor can be improved significantly.
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