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Due to the environment, age and some factors of human operation, the inverter's service life is greatly reduced, and various faults occur in use.
1. The static test result of the inverter to judge the fault Firstly, a static test can be done on the inverter. The general-purpose inverter mainly includes the following parts: (1) rectifier circuit; (2) DC intermediate circuit; (3) inverse Variable circuit; (4) control circuit.
The static test is mainly a test of the high-power transistor (power module) of the rectifier circuit, the DC intermediate circuit and the inverter circuit part, and the tool is mainly a multimeter. The rectifier circuit mainly tests the forward and reverse of the rectifier diode to judge whether it is good or bad. Of course, we can also test it with a withstand voltage gauge. The DC intermediate circuit is mainly for measuring the capacity and withstand voltage of the filter capacitor. We can also observe whether the safety valve on the capacitor is popped open or not, whether it is leaking or not, to judge whether it is good or bad. The quality of the power module is mainly judged. Judgment of the freewheeling diode in the power module. For the IGBT module, we also need to judge whether it can be turned on and off in the presence of a trigger voltage.
2. Determine the location of the fault by the display of the inverter
(1) OC. Overcurrent fault This may be the most common fault in the inverter. First, troubleshoot due to parameter problems should be eliminated. For example, current limitation, too short acceleration time may lead to overcurrent. Then we have to judge whether the current detection circuit is faulty. Take the FVR075G7S-4EX as an example: We sometimes see that the FVR075G7S-4EX will have a current display when the motor is not connected. Where does the current come from? At this time, we must test its three Hall sensors. In order to determine the damage of the phase sensor, we can open the machine once every phase sensor is removed to see if there is an overcurrent display. After this test, it can basically be eliminated. OC failure.
(2) OV. Overvoltage faults must first eliminate faults caused by parameter problems. For example, the deceleration time is too short, and the overvoltage caused by the regenerative load, etc., then we can look at whether there is a problem with the input side voltage. Finally, we can look at whether the voltage detection circuit has a fault, the voltage sampling of the general voltage detection circuit. Points are the voltages of the intermediate DC link. Let's take Sanken SVF303 as an example. It is sampled by DC loop (DC of about 530V) and is stepped down by a large resistor. It is isolated by optocoupler. When the voltage exceeds a certain value, it shows “5” overvoltage ( This machine is a digital tube display.) We can see if the resistance is oxidized and the optocoupler has a short circuit.
(3) UV. Undervoltage We can first look at the input side voltage for a problem, then look at the voltage detection circuit, fault diagnosis and overvoltage are the same.
4) FU. Fast-Fuse Faults Most of the currently available inverters have introduced the fast-fuse fault detection function. (especially high-power inverters) Take the LG030IH-4 inverter as an example. It mainly samples and detects the voltage behind the fast-melting front. When the fast-melting damage is inevitable, there will be no voltage at the fast-melting end. At this time, the isolated optocoupler acts and a FU alarm occurs. Replacing the fast melt can solve the problem. In particular, it should be noted that it is necessary to judge whether there is a problem with the main circuit before replacing the fast melt.
(5) OH. Main cause of overheating The internal heat dissipation of the inverter is not good. We can check the cooling fan and ventilation channel.
(6) SC. Short circuit fault We can check if there is a short circuit inside the inverter. Detecting the internal circuit may not necessarily have a short circuit. At this time, we can detect that the power module may be faulty. If the drive circuit is normal, replace the power module and it should be able to repair the machine.
There are many kinds of faults in the inverter. The maintenance workers in the first steelmaking workshop have a late contact, and little is known about the basic knowledge of the inverter. We can only sum up in practice and find a set of fast and effective treatment of the fault of the inverter. Method.