With the increase of energy conservation and environmental protection, as the most direct product of energy saving, the application of frequency converter has encountered a rare good opportunity. As time went by, the frequency converter also entered a period of high failure. When a fault occurs, first refer to the instruction manual of the inverter for judgment and processing. We have accumulated some experience in troubleshooting, maintenance and repair during the maintenance process.
Inverter common troubleshooting experience sharing
1 Introduction
With the increase of energy conservation and environmental protection, as the most direct product of energy saving, the application of frequency converter has encountered a rare good opportunity. As time went by, the frequency converter also entered a period of high failure. When a fault occurs, first refer to the instruction manual of the inverter for judgment and processing. We have accumulated some experience in troubleshooting, maintenance and repair during the maintenance process.
2The keyboard has no display after power-on.
(1) Check if the input power is normal. If it is normal, measure whether the voltage of the DC bus p and n terminals is normal: if there is no voltage, you can cut off the power to check whether the charging resistor is broken or not;
(2) After checking the voltage of p and n terminals is normal, the keyboard and keyboard line can be replaced. If there is still no display, it is necessary to check whether the 26p cable connected to the main control board and the power supply board is loose or broken when the power is off;
(3) If the switching power supply works normally after power-on, the relay has a sound of suction, the fan is running normally, and there is still no display, then it can be judged that the crystal oscillator or resonant capacitor of the keyboard is bad. At this time, the keyboard can be replaced or the keyboard can be repaired;
(4) If everything else is normal after power-on, but there is still no display, the switching power supply may not work. At this time, the power supply of p and n should be removed after power failure, check whether the static of ic3845 is normal (check by experience), if ic3845 Static normal, at this time after the p, n plus DC voltage 18v / 1w Zener diode about 8v voltage, but the switching power supply does not work, power off check whether the rectifier diode on the secondary side of the switch transformer has a breakdown short circuit;
(5) After power-on, the 18v/1w Zener diode has voltage, and there is still no display. It can remove some external plug-in lines, including relay line plug and fan line plug, and check whether the fan and relay have short circuit.
(6) After the p and n terminals are powered on, the voltage across the 18v/1w Zener diode is about 8v. Use an oscilloscope to check whether the input pin 4 of the ic3845 has a sawtooth wave, and whether the output pin 6 has an output.
(7) Check the output terminals of the switching power supply +5v, ±15v, +24v and whether each drive power supply has a short circuit to the ground and between the poles.
3 keyboard display is normal, but can not operate
(1) If the keyboard display is normal, but each function key cannot be operated, check whether the keyboard used and the main control board match (whether or not it contains ic75179). For machines with internal and external keyboard operations, check the settings you have set. Is the position of the DIP switch correct?
(2) If the display is normal, only some of the buttons cannot be operated, you can check if the button micro switch is defective.
4 potentiometer can not speed
(1) First check if the control mode is correct;
(2) Check whether the given signal selection and analog input mode parameter settings are valid;
(3) Whether the setting of the DIP switch of the main control board is correct;
(4) If all of the above are correct, the potentiometer may be defective. Check whether the resistance is normal.
5 overcurrent protection (oc)
(1) When “fooc†is displayed on the keypad of the inverter, “oc†flashes. At this time, press “∧†to enter the fault inquiry status, and the running frequency, output current, running status, etc. at fault can be found, according to the running status. And the magnitude of the output current, determine whether its "oc" protection is overload protection or vce protection (output short circuit, drive circuit failure and interference, etc.);
(2) If it is determined at the time of inquiry that the current is too large due to the heavy load, the acceleration time and the appropriate v/f characteristic curve are appropriately adjusted;
(3) If the Motor is not connected, the inverter will skip “oc†protection. It should be powered off to check if igbt is damaged. Check if the junction capacitance between igbt's freewheeling diode and ge is normal. If it is normal, check the drive circuit: check if the drive line is in the correct position, whether there is offset, whether it is virtual insertion; check whether it is caused by hall and line fault "oc"; check the drive circuit amplification component (such as ic33153, etc.) Or whether the optocoupler has a short circuit; check whether the drive resistor has open circuit, short circuit and resistance variable phenomenon;
(4) If “oc†is skipped during operation, it should be checked whether the motor is blocked (mechanical jam), causing overcurrent due to sudden change of load current;
(5) When “oc†is skipped during deceleration, the deceleration time and deceleration mode should be adjusted according to the type and weight of the load.
6 overload protection (ol)
(1) When “fool†is displayed on the keypad of the inverter, “ol†flashes. At this time, press “∧†to enter the fault inquiry status, and the running frequency, output current, running status, etc. can be found according to the running status. And the output current, if the output current is too large, the load may be too heavy. At this time, the acceleration and deceleration time and v/f curve, torque boost, etc. should be adjusted. If it is still overloaded, it should be considered to reduce the load or replace it. Large capacity inverter
(2) If the output current is not large when the fault is queried, check whether the parameters of the electronic thermal overload relay are appropriate.
(3) Check if the hall and the line are bad.
7 overheat protection (oh)
(1) Check if the temperature switch wire plug is plugged in, use a multimeter to check if the temperature switch wire is disconnected, if it is disconnected, it can be concluded that the temperature switch wire is open or the temperature switch is damaged;
(2) Bad fan causes overheating protection;
(3) The ambient temperature is too high, the heat dissipation effect is poor, and the internal temperature of the inverter is high, resulting in overheat protection;
(4) For the seven-unit igbt inverter with rectifier bridge, the temperature detection is based on the resistance change of the thermistor inside igbt for temperature detection. If “oh†overheat protection occurs, there are the following reasons: comparator Bad, the output is high; the comparator compares the resistance value, the comparison voltage is lower; the internal resistance of the igbt is abnormal.
8 overvoltage protection (ou)
(1) Over-voltage protection occurs during the deceleration of the inverter, which is caused by the large inertia of the load. At this time, the deceleration time should be extended. If it is still invalid, the brake unit and the braking resistor can be added to consume energy.
(2) The overvoltage protection caused by replacing the power supply board or the main control board needs to adjust the vpn parameter resistance;
(3) If the input power supply voltage is higher than the rated voltage of the inverter, overvoltage may occur.
9 undervoltage protection (lu)
(1) First check whether the input power supply voltage is normal, whether the wiring is good, and whether there is a lack of phase;
(2) Is the "04" value parameter resistance appropriate?|
(3) The undervoltage protection caused by replacing the power supply board or the main control board needs to adjust the vpn parameter resistance;
(4) Voltage detection loop, poor device such as op amp can also cause undervoltage.
10 relay does not pull in
(1) First check whether the input power is abnormal (if it is equal);
(2) Check if the connection between the power supply board and the capacitor board is correct and there is looseness;
(3) Check if the 26p cable between the main control board and the power board has poor contact or disconnection, which causes the rec control signal to be invalid and the relay to not pick up;
(4) The components of the relay pull-in loop also cause the relay to not pick up;
(5) The internal of the relay is bad (such as coil disconnection, etc.).
11 has frequency display, but no voltage output
(1) After the inverter runs, there is a running frequency, but there is no voltage output between u, v, w. At this time, it is necessary to check whether the carrier frequency parameter is lost;
(2) If the carrier frequency parameter is normal, run the inverter and check whether the drive waveform is normal with an oscilloscope;
(3) If the driving waveform is not normal, check whether the spwm waveform sent by the cpu of the main control board is normal. If it is abnormal, the cpu is faulty. If the spwm waveform of the main control board is normal, you need to replace the 26p cable and try again. If the drive board drive waveform is still abnormal, the drive circuit part is faulty and needs to be repaired or replaced.
12 Conclusion
After the fault occurs, it is necessary to have a preliminary diagnosis of the cause of the fault based on the fault phenomenon. Don't worry, calm down and slowly check the cause and carefully check the device for malfunction.
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