| 摘要 |
PURPOSE:To permit operation of load to be stably continued and thus eliminate adverse effect supon the product by controlling the output voltage of a noise-free battery capable of ready maintenance to be substantially equal to the output voltage of an inverse converter. CONSTITUTION:A battery 6 having a lamination of battery cells is always charged to a constant voltage by a floating charger, and a power supply unit comprising the battery 6 and a voltage switch 10 can provide a variable voltage by changing the number of battery cells in the lamination. This DC voltage is coupled to a voltage detector 11. A power supply unit voltage signal V1 produced from a detector 11 and an inverse converter voltage feedback signal V2 obtained from a detector 12 connected to the output side of an inverse converter 4 are combined together to obtain an error signal, which is amplified by an error amplifier 13, the output of which is in turn used to rotate a drive motor 10B assembled in the switch 10. Thus, even in case of a momentary power stoppage or voltage drop it is possible to steadily continue the operation of the load. |
