| 摘要 |
PURPOSE:To improve the response of an AC-side power factor improving circuit consisting of a switching element and a reactor, by detecting an average value of the AC-side current to determine the conduction mode of the switching element. CONSTITUTION:The voltage from an AC power source 1 is inputted to a voltage multiplying rectifier 3 through a power-factor improving circuit 2 and is rectified by the circuit 3 and is smoothed in a smoothing circuit 4 and is supplied to a load 5. The circuit 2 consists of diodes D1 and D2, transistors TRs T1 and T2, and a reactor Ls, and a shunt RS2 for current detection is inserted. An average value in the AC-side current is detected by the shunt RS2, and on the basis of the detected result, conduction rates and switching operation times in one cycle of the AC current of TRs T1 and T2 are determined to obtain a maximum power-factor. Thus, a load can be selected in the same potential, a means such as a photocoupler for information transmission between different potentials is unneccessery, and the time delay of information or the like is eliminated. |
