1. Switching power supply is damaged
Switching power supply damage is the most common fault of many inverters, usually caused by short circuit of the switching power supply. In the design of switching power supply lines of many inverters, Yaskawa inverter is quite successful. The 616G3 uses a two-stage switching power supply, which is similar to the Fuji G5. The first-stage switching power supply converts the DC voltage of more than 500 volts on the DC bus side into a DC voltage of more than 300 volts. Then, through the secondary coil of the high-frequency pulse transformer, output lower voltages such as 5V, 12V, and 24V for the inverter's control board, drive circuit, and detection circuit to be used for power supply. In the design of the second-stage switching power supply, the Yaskawa inverter uses a controllable voltage regulator called TL431 to adjust the duty cycle of the switching tube to achieve stable output voltage. The LG inverters we talked about in previous issues also used similar control methods. The QM5HL-24 and TL431 used as switching tubes are all devices that are more susceptible to damage. In addition, if we hear a harsh scream in the use, this is caused by the pulse transformer, it is likely that there is a short circuit on the output side of the switching power supply. We can find the fault from the output side. In addition, when there is no display, no voltage at the control terminal, DC12V, 24V fan does not work, etc., we should first consider whether the switching power supply is damaged.
2. SC failure
The SC fault is a common fault of Yaskawa inverters. The IGBT module is damaged, which is one of the causes of the SC fault alarm. In addition, damage to the drive circuit can easily lead to SC failure alarms. Yaskawa 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, Yaskawa's lower bridge drive circuit uses the optocoupler PC929, which It is an optocoupler with an internal amplifier circuit and a 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 the damage of the IGBT module. The first is the failure of the external load, which causes damage to the IGBT module, such as short-circuit of the load, stalling, and the like. Secondly, the aging of the driving circuit may also cause the driving waveform to be distorted, or the driving voltage fluctuates too much and the IGBT is damaged, thereby causing the SC fault alarm.
3. OH - overheating
Overheating is a malfunction that you usually encounter. When this happens, first think about whether the cooling fan is running. Observe the outside of the machine to see if the fan is running. In addition, for the machine above 30kW, there is also a cooling fan inside the machine. The damage of this fan will also cause OH alarm.
4. UV - undervoltage fault
When an undervoltage fault occurs, first check if the input power supply is out of phase. If there is no problem with the input power supply, then we should check if there is a problem with the rectifier circuit. If there is no problem, then it depends on whether there is a problem on the DC detection circuit. For a 200V class machine, when the DC bus voltage is lower than 190VDC, a UV alarm will appear; for a 400V class machine, a fault alarm will occur when the DC voltage is lower than 380VDC. Mainly check if the step-down resistor is open circuit.
5. GF-ground fault
The ground fault is also a fault that will normally be encountered. In addition to the cause of the problem of grounding of the motor, the most likely part of the fault is the Hall sensor. The Hall sensor is easily affected by environmental factors such as temperature and humidity. A drift occurred, causing the GF to alarm.
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