| 摘要 |
PURPOSE:To enable DC braking control on a loaded motor even when a part of switching elements is faulty, by selecting sequentially the switching elements combined differently every time when an overcurrent flows through an inverter. CONSTITUTION:When a control power source is closed under the condition that all transistors constituting an inverter circuit are in a normal state, an initial reset circuit 6 resets a flip-flop circuit 7 and thereby a switching circuit 28 is switched onto the side of a waveform composing circuit 11. An induction motor 3 is driven based on a set value of an inverter frequency setting unit 8. When any fault occurs in the inverter circuit, the transistors constituting the inverter circuit are all put in the OFF state. After a prescribed time, a shift register 25 selects a different transistor pair circuit in the inverter circuit through a time delay circuit 24 and makes it perform an operation of DC braking of the motor. |
