| 摘要 |
PURPOSE:To prevent the abnormal overheat of a damping resistor positively by detecting the abnormal conduction of a switching element connected in series with the damping resistor and stopping the operation of an inverter. CONSTITUTION:An inverter has a smoothing capacitor 3 smoothing an output from a rectifier circuit 2 and an inversion circuit 4, and supplies a motor 5 as load with an AC output. A damping resistor 6, a switching element 7 connected in series with the damping resistor and a damping control circuit 8 are mounted, and a voltage over-rise by regenerative energy on the deceleration of the motor is inhibited. A photo-coupler 9, a limiting resistor 10 for primary side currents and a load resistor 11 are fitted as conduction detection means to the damping resistor 6 at that time. Accordingly, when regenerative energy is consumed by the control resistor 6, the actual conduction of the switching element 7 and the state of the actual load of the damping resistor 6 are monitored by the damping control circuit 8, and the conduction of the switching element 7 is inhibited when conduction more than a specified value continues.
|
