| 摘要 |
PURPOSE:To reduce the loss in low speed operation and keep off heat generation to perform stable operation, by thinning out the ignition of thyristers in a specified low speed operating mode. CONSTITUTION:When an operating mode command circuit 10 assigns a normal mode, a gate control circuit 9 performs feedback control so as to operate in rated speed in controlling thyristers T1-T10 corresponding to the firing angle set out in an operation control circuit 8 in proportion to the deviation between the speed command and the speed signal. When the operating mode command circuit 10 assigns a specified low speed mode, the gate control circuit 9 is separated from the operation control circuit 8 and comes up with thinning out the ignition of thyristers. On this account, as the rotating speed is slowed down at 1/2 of the rotating speed of the rotating flux generated inside an induction motor, the slip in low speed operation gets smaller, the loss inside the induction motor is reduced and the generation of heat is kept off. |
