| 摘要 |
The present invention is equipped with a transformer (13), which has a primary coil wherein a coil between coil terminals a-b and a coil between coil terminals b-c are connected in series; and switching circuit units (18), which select any of the coils of the primary coil and apply a power supply voltage. In addition, a control unit (15) switches the coil of the primary coil supplying the electricity two or more times during one cycle of voltage deviation of an alternating current power supply (1), thereby causing the alternating current power supply to operate as a power supply which uses the transformer (13) with an appropriate turn ratio corresponding to the changing power supply voltage. By lowering the turn ratio and performing an appropriate switching operation when the power supply voltage is high the efficiency can be increased, and by increasing the turn ratio when the power supply voltage is low, it is possible to output prescribed power even with a low power supply voltage. |
