The detection and analysis of fault circuit of inverter is the key step to ensure the stable operation of inverter. The following is a detailed guide to the detection and analysis of inverter fault circuits:
1. Static testing
Static test is to detect the inverter circuit without power, mainly including rectifier circuit test and inverter circuit test.
Rectifier circuit test:
Locate the P and N terminals of the DC power supply inside the inverter.
Use the multimeter resistance X10 to test, the red pen is connected to the P end, and the black pen is respectively measured at the R, S, and T inlet ends. Under normal circumstances, there should be a resistance value of about tens of ohm, and the resistance value of the three phases is basically balanced.
If the resistance value is unbalanced or the resistance is infinite when the red pen is connected to the P end, it indicates that the rectifier bridge or the starting resistance is faulty.
Inverter circuit test:
The red watch pen is connected to the P end, and the black watch pen is respectively connected to the frequency converter outlet U, V, and W. Under normal circumstances, there should be a resistance value of tens of ohm, and the resistance values are basically the same. In the inverse test, the resistance value should be infinite.
If the test result does not meet the preceding standards, the inverter module is faulty.
2. Dynamic test
Dynamic test is a power-on test carried out after the static test is normal, mainly including input voltage /confirm/iation, interface connection check, no-load test and on-load test.
Input voltage /confirm/iation:
Ensure that the input voltage is correct. Avoid connecting 380V power to 220V inverter, otherwise it may cause explosion.
Interface connection check:
Check whether the connection of each interface of the inverter is correct and tight. Abnormal connection may lead to failure or explosion.
No-load test:
If no fault is displayed, check whether the parameters are abnormal. Restore the parameters and perform no-load test.
Observe the U, V, and W three-phase output voltage. If there is a lack of phase or a three-phase imbalance, the module or driver board is faulty.
On-load test:
When the output voltage is normal and the three phases are balanced, the load test is carried out, and the full load test is best.
3. Fault diagnosis and handling
based on the dynamic test results, you can determine and handle the following faults:
Rectifier module damage:
Cause: Generally caused by grid voltage or internal short circuit.
Treatment: After removing the internal short circuit, replace the rectifier bridge. When on-site processing, it should focus on checking the user's power grid, such as the power grid voltage, whether there are welding machines and other equipment that pollute the power grid.
Inverter module damage:
Cause: Usually caused by motor, cable damage or drive circuit failure.
Solution: After repairing the drive circuit, replace the module. After replacing the drive board, you must also pay attention to check the motor and the connecting cable, and run the inverter when there is no fault.
Power-on None:
Cause: The switching power supply may be damaged or the soft charging circuit is damaged.
Action: Inspect and replace damaged parts.
Overvoltage or undervoltage:
Cause: Generally caused by input phase deficiency, circuit aging or circuit board moisture.
Solution: Check the input power supply, circuit aging and circuit board moisture, and take appropriate measures.
Overcurrent or ground short circuit:
Cause: Usually caused by damage to the current detection circuit, such as Hall components, operational amplifiers, etc.
Action: Check and replace damaged current detection circuit components.
Startup display overcurrent:
Cause: It is generally caused by damage to the drive circuit or inverter module.
Solution: Check and repair the drive circuit or replace the inverter module.
On-load display overload or overcurrent:
Cause: May be caused by improper parameter setting, driver circuit aging or module damage.
Solution: Adjust the parameters and replace the corresponding parts.