| 摘要 |
PURPOSE:To decrease the loss of a motor by a method wherein a detecting means for power in which the product of an instantaneous value of voltage and an instantaneous value of currents becomes positive and power in which the product becomes negative is mounted, and input voltage is adjusted so that proportional relationship is formed between both power. CONSTITUTION:A power controller 3 is installed between an AC power source 1 and an induction motor 2, and the controller 3 has a detecting means 11 for winding voltage and a detecting means 12 for winding currents, inputs the output of both means to a power detecting means 13 and detects power in which the product of these instantaneous values becomes positive and power in which the product becomes negative. Both power is computed by means of a computing element 17 so that proportional relationship is formed between both power, and the voltage of the AC power source 1 is adjusted through a voltage adjusting means 19. Thus, the relationship of service power and feedback power is proportioned, and voltage applied to the winding of the motor 2 is adjusted to the variation of AC line voltage and the change of a load condition. Consequently, input can be minimized to the output of the motor 2. |
