| 摘要 |
PURPOSE:To enable the improved operation which can further improve the effect of electric power-saving by performing the prescribed operation which alleviates the power consumed at a normal condition as much as possible. CONSTITUTION:The speed deviation between a speed instruction amount N and an actual speed detection signal omegan and hence a signal relative to a slip is temporarily amplified by an amplifier 7, the amplified signal is inputted as a current instruction amount representing the motor torque to a comparator 13 of a minor loop current controlling system, the current instruction amount is compared with a current detection signal from a diode 12, a signal obtained by amplifying the current deviation therebetween used to control the DC voltage of a power rectifier 1, and the amplitude of the primary current of the load motor 4 is thus controlled. Since the slip frequency omegas is so controlled as to be the reciprocal of the time constant of the secondary side, the maximum torque can be obtained at the minimum primary current at all times even under any output frequency. |
