(1) Overcurrent in operation means that the drag system has an overcurrent during the working process. The reason is mainly from the following aspects: 1 The motor encounters an impact load, or the transmission mechanism is “stuck”, causing a sudden increase in the motor current.
2 The output side of the inverter is short-circuited, such as a short circuit between the output terminals and the motor, or a short circuit inside the motor.
3 The inverter itself is not working properly. For example, two inverter devices of the same bridge arm in the inverter bridge are abnormal during the alternate work. For example, due to the high ambient temperature or the aging of the inverter device itself, the parameters of the inverter device are changed, resulting in one device being turned on during the alternation process, and the other device is still turned off in the future, causing the same The “straight through” of the upper and lower devices of one bridge arm makes the short circuit between the positive and negative terminals of the DC voltage.
(2) Over-current when the speed is increased When the inertia of the load is large and the speed-up time is set too short, it means that during the speed-up process, the working efficiency of the inverter rises too fast, and the synchronous speed of the motor rises rapidly. However, the rotation speed of the motor rotor cannot be kept up due to the large inertia of the load, and as a result, the speed increase current is too large.
(3) Overcurrent in the deceleration When the inertia of the load is large and the deceleration time is set too short, it will cause overcurrent. Because the speed reduction time is too short, the synchronous speed decreases rapidly, and the rotor of the motor maintains a high speed due to the inertia of the load. At this time, the speed at which the rotor winding cuts the magnetic line is too large to generate an overcurrent.
Inverter overcurrent processing method
(1) Tripping at a speed up at start-up, this is a very serious over-current phenomenon. The main check: whether the working machine is stuck; whether there is a short circuit on the load side, check whether there is a short circuit to the ground with a megohmmeter; The module is not damaged; the starting torque of the motor is too small, and the drag system cannot be turned.
(2) Do not trip immediately when starting, but trip during operation, the main check: the speed increase time setting is too short, lengthen the acceleration time; the deceleration time setting is too short, lengthening the deceleration time; torque compensation (U/f ratio The setting is too large, causing too much no-load current at low frequencies: the electronic thermal relay is improperly set, and the operating current is set too small, causing the inverter to malfunction.