Talking about the common fault of frequency converter

In recent years, driven by the rapid development of electronic technology, computer technology and automatic control technology, the continuously updated equipment has brought unlimited convenience to the production and management of enterprises, and has created tremendous wealth. Under the call of global energy exhaustion, the development of energy-saving and low-consumption countries, and the fierce market competition, motor AC variable frequency speed control technology has become a major means of improving product quality, improving the environment, and saving energy. The frequency converter meets the saving theme and has been widely used in factories. However, due to the structural characteristics of the inverter, not only the fundamental wave is generated in the process of use, but also a large part of the higher harmonics will cause adverse reactions. Causes the frequency converter to malfunction. By analyzing the faults, the analysis can be promptly discovered and the problems can be solved effectively.

1 External Causes of Inverter Faults and Countermeasures There are many causes of inverter faults, which are summarized as internal and external.

1.1 Impact and Treatment of Installation Environment Since the inverter is an electronic device device, the environmental requirements are more stringent, and the environmental impact on the inverter can also be seen from the product specification. For example, vibration can cause damage to electronic components. Wet environments, corrosive gases, and dust can cause device corrosion, poor contact, and reduced insulation. Temperature is another major “cause” of inverter performance because the inverter is in operation. The temperature will continue to rise, if the outside temperature is also high, poor heat dissipation will affect the function of the inverter.

Treatment countermeasures: When installing the inverter, it is necessary to maintain the stability of the inverter. For the occasions with large vibration impact, precautions should be taken, such as the use of rubber shock absorbers; the installation environment should be kept dry to prevent corrosive gases from invading the inverter. For the hazard of dust, the frequency converter should be cleaned periodically to keep it clean. The temperature of the installation environment should also be reasonably controlled. When there is sunlight, curtains must be used to cover the air conditioner. If the temperature is still relatively high, air conditioners may be properly installed.

1.2 Abnormal effects of power supply and countermeasures Because the power lines are exposed outdoors for a long time, they often suffer from wind, rain, snow, and frost, which leads to the aging of the lines, and the phenomenon of phase loss, low voltage, power failure, etc. during the power supply. The changing voltage waves are easy. Influencing the frequency converter, resulting in abnormal operation, affecting its performance. Over time, failure will certainly occur.

Handling countermeasures: When the power supply is installed, try to separate the power supply of the transformer from other electrical appliances. When the power is too high, the normal voltage required by the inverter cannot be satisfied. For the equipment that can still operate for a little time after the power failure, after the voltage loss is restored, the over-current during acceleration can be prevented by the speed-measuring motor speed measurement, and the damage to the inverter can be reduced at least. For equipment requiring continuous operation after a power outage, an automatic switching non-discharge device shall be installed at the time of installation, such as a diode-input frequency converter. However, in the event of a power outage, excessive currents often occur in the rectifiers. Operation in the long term will affect the life and performance of the inverter and should be checked as soon as possible.

1.3 External electromagnetic induction interference and countermeasures If there is electromagnetic interference around the inverter, it will invade the inverter through radiation, causing the control loop to malfunction, which causes abnormal operation, shutdown, and destruction. Treatment countermeasures: To solve the external electromagnetic interference, it is necessary to reduce the generation of interference, such as relays and contactor control coils around the inverter, plus shock wave voltage receiving devices, such as RC surge absorbers; for the use of shielded cables The loop must be operated as required. If the line is long, a reasonable relay method can be adopted according to the actual situation; install a radio noise filter at the input and output terminals of the inverter to reduce the input higher harmonics and reduce the power line to the electronic device. The impact of noise, while reducing the impact of the output line noise on the drive.

2 Intrinsic Causes of Inverter Failure and Countermeasures The inverter is faulty, not only due to external influences, but also due to internal causes. 2.1 Unreasonable parameter setting of inverter and countermeasures In order to make the inverter run normally, in addition to the normal installation, the parameter setting is also very important. If the parameters are not set properly, it will not be able to meet the running demand conditions, but will result in starting and braking. Failed, so parameters must be set correctly when used.

Treatment countermeasures: In order to avoid unreasonable parameter setting, the inverter will fail. Set it strictly in accordance with the instructions or relevant regulations. For example, in the speed control setting, final determination shall be made through static or dynamic identification; The instruction manual is generally set to start the panel. However, in practice, the user can set the parameters according to the actual conditions required by the work, and by properly setting the parameters, the normal operation of the inverter can be ensured.

2.2 Overvoltage faults and countermeasures The overvoltage of the inverter is mainly on the DC bus. Under normal conditions, the inverter has a normal operating voltage range. In this range, the inverter can operate normally. Once the voltage exceeds this range, the inverter Overvoltage faults are likely to cause damage to the inverter, such as overvoltage faults caused by high power supply voltage; overvoltage faults caused by DC link voltage exceeding trip voltage, etc., regardless of overvoltage faults caused by such causes, It will have an adverse effect.

Remedy: Make sure that the power supply voltage is within the normal operating voltage range of the inverter and perform periodic inspections. Also check that the deceleration time of the inverter frequency is correct. If any settings are found.