1. Overcurrent
Overcurrent is the most frequent alarm phenomenon of the inverter.
(1) When restarting, the inverter trips as soon as the speed increases. This is a very serious phenomenon of overcurrent. The main reasons are: load short circuit, mechanical parts are stuck; inverter module is damaged; motor torque is too small, etc.
(2) It trips when powered on. This phenomenon generally cannot be reset. The main reasons are: module is bad, drive circuit is bad, current detection circuit is bad. When restarting, it does not trip immediately but during acceleration. The main reasons are: acceleration time is set too short, current upper limit is set too small, torque compensation (V/F) is set too high.
2. Overvoltage
Overvoltage alarm usually occurs when the machine is shut down. The main reason is that the deceleration time is too short or there is a problem with the brake resistor and brake unit.
3. Undervoltage
Undervoltage is also a problem we often encounter during use. It is mainly because the main circuit voltage is too low (220V series is lower than 200V, 380V series is lower than 400V). The main reasons are: damage to one of the rectifier bridges or abnormal operation of the three thyristors may cause undervoltage faults. Secondly, damage to the main circuit contactor may cause DC bus voltage loss on the charging resistor, which may cause undervoltage. Another problem is that the voltage detection circuit fails and causes undervoltage.
4. Overheating
Overheating is also a common fault. The main reasons are: the ambient temperature is too high, the fan is blocked, the temperature sensor performance is poor, and the motor is overheated.
5. Output imbalance
Output imbalance is generally manifested as motor shaking and unstable speed. The main reasons are: module failure, drive circuit failure, reactor failure, etc.
6. Overload
Overload is also one of the faults that the inverter frequently beats. When we see overload phenomenon, we should first analyze whether it is the motor overload or the inverter itself overload. Generally speaking, the motor has a strong overload capacity. As long as the motor parameters in the inverter parameter table are properly set, the motor overload will not occur. However, the inverter itself is prone to overload alarm due to its poor overload capacity. We can detect the output voltage of the inverter.
7. Switching power supply damage
This is the most common fault of many inverters, usually caused by a short circuit in the load of the switching power supply. Some inverters use a new pulse width integrated controller UC2844 to adjust the output of the switching power supply. At the same time, UC2844 also has current detection, voltage feedback and other functions. When there is no display, no voltage at the control terminal, DC12V, 24V fan does not run, etc., we should first consider whether the switching power supply is damaged.
8. SC Failure
SC failure is a common fault in some inverters. IGBT module damage is one of the reasons for SC fault alarm. In addition, damage to the drive circuit can also easily lead to SC fault alarm. In the design of the drive circuit, the upper bridge uses the drive optocoupler PC923, which is an optocoupler with an amplifier circuit dedicated to driving the IGBT module. The lower bridge drive circuit uses the optocoupler PC929, which is an optocoupler with an internal amplifier circuit and detection circuit. In addition, motor jitter, three-phase current, voltage imbalance, frequency display but no voltage output, these phenomena may be IGBT module damage. There are many reasons for IGBT module damage. First, the external load fails and causes the IGBT module to be damaged, such as load short circuit, stall, etc. Secondly, the aging of the drive circuit may also cause the drive waveform to be distorted, or the drive voltage fluctuates too much, causing IGBT damage, thereby causing SC fault alarm.
9. GF—ground fault
Ground fault is also a common fault. In addition to eliminating the cause of the motor grounding problem, the most likely part to fail is the Hall sensor. Due to the influence of environmental factors such as temperature and humidity, the working point of the Hall sensor is easy to drift, resulting in GF alarm.
10. Current Limitation Operation
During normal operation, we may encounter the inverter prompting the current limit. For general inverters that cannot work normally and smoothly when the current limit alarm appears, the voltage (frequency) must be lowered first until the current drops to the allowable range. Once the current is lower than the allowable value, the voltage (frequency) will rise again, causing system instability.
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