Inverter fault phenomenon and solution
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(1) Fault P.OFF
Kang Volt inverter power-on display P.OFF delay 1 ~ 2s shows 0, indicating that the inverter is in standby mode. In applications, if P.OFF and not 0 are displayed after the inverter is powered on, the main reasons are: input voltage is too low, input power is missing, and the inverter voltage detection circuit is faulty. The three-phase input of the power supply should be measured before processing. Voltage, R, S, and T terminals The normal voltage is three-phase 380V. If the input voltage is lower than 320V or the input power supply is out of phase, the external power supply should be removed. If the input power is normal, it can be judged as the internal voltage detection circuit or phase failure protection fault of the inverter. For the Conv G1/P1 series inverter of 90kW and above, the main cause of the fault is the internal phase missing detection circuit abnormality. The phase loss detection circuit consists of Two single-phase 380V/18.5V transformers and rectifier circuits constitute the majority of faults for the detection of transformer faults. The output voltage of the transformer can be measured during processing.
(2) Fault ER08
The ER08 fault code in Convo invertor indicates that the inverter is in undervoltage fault condition. The main reason is that the input power supply is too low or the phase is missing, the internal voltage detection circuit of the inverter is abnormal, and the inverter main circuit is abnormal. The universal inverter voltage input range is 320V~460V. Under the full load operation of the inverter in practical applications, undervoltage protection may occur when the input voltage is lower than 340V. At this time, the input voltage of the grid or the derating of the inverter should be used; If the input voltage is normal and the inverter has ER08 fault during operation, it can be judged as an internal fault of the inverter. As shown in Figure 1, the KS contactor in the main loop may trip open, so that the current limiting resistor is connected in series to the main circuit when the inverter is running. At this time, if the inverter runs with load, it will appear ER08 fault. At this time, it can be excluded whether the contactor is damaged or the contactor control circuit is abnormal. If the main circuit of the inverter is normal, the cause of the ER08 alarm is mostly the fault of the voltage detection circuit. Generally, the voltage detection circuit of the inverter is a set of outputs of the switching power supply. After the sampling and comparison circuit is given to the CPU processor, when the set value is exceeded, the CPU outputs a fault blocking signal according to the comparison signal to block the IGBT and display the fault code at the same time. .
(3) Fault ER02/ER05
Fault code ER02/ER05 indicates that the inverter has overcurrent or overvoltage fault during deceleration. The main reason is that the deceleration time is too short and the load feedback energy is too large to be released in time. If the motor drives a large inertia load, when the frequency of the inverter (that is, the synchronous speed of the motor) decreases, the actual speed of the motor may be greater than the synchronous speed. At this time, the motor is in a state of power generation. This part of the energy will pass through the inverter circuit of the inverter. Return to the DC loop so that the inverter has overvoltage or overcurrent protection. During the on-site treatment, the deceleration time of the inverter can be prolonged without affecting the production process. If the inertia of the load is large and it is required to stop within a certain period of time, an external braking resistor and a braking unit must be installed. /P2 series inverters with 22kW or less have built-in braking units. Only external braking resistors can be added. Resistance selection can be selected according to the standard in the product description. For models with power 22kW or more, an additional braking unit is required. And braking resistors.
ER02/ER05 fault usually occurs only during the inverter deceleration stop. If the inverter has other faults in the operating state, it may be the internal switching power supply part of the inverter, such as voltage detection circuit or current detection circuit is abnormal. caused.
(4) Fault ER17
Code ER17 indicates current detection failure. Current detection of general-purpose inverters generally uses a current sensor to detect, display, and protect the inverter's operating current by detecting the two-phase output current of the inverter. The output current is passed through a current sensor (as shown in Figure 2). H1, H2 are current sensors) output a linear voltage signal, which is sent to the CPU processor by the amplified comparison circuit. The CPU processor judges whether the inverter is in an over-current state according to different signals. If the output current exceeds the protection value, the fault blockade protection circuit operates. , block IGBT pulse signal to achieve protection function.
The main cause of ER17 fault in Convo invertor is current sensor fault or current detection amplification and comparison circuit abnormality. The former can be solved by replacing the sensor. The latter is mostly related to the current detection IC circuit or IC chip operating power supply abnormality, which can be replaced by the relevant IC or Repair related power supply solution.
(5) Fault ER15
The code ER15 indicates that the inverter module IPM or IGBT is faulty. The main reason is that the output is shorted to ground, the cable from the inverter to the motor is too long (more than 50m), and the inverter module or its protection circuit is faulty. Remove the motor cable at the site, measure the inverter inverter module, observe the output for short circuit, and check whether the motor is short-circuited to the ground and whether the motor line exceeds the allowable range. If the above conditions are normal, it may be the internal IGBT module of the inverter. Drive or protection circuit is abnormal. The general IGBT over-current protection is operated by detecting the voltage drop of the tube when the IGBT is turned on. When the IGBT is normally turned on, its saturation voltage drop is very low. When the IGBT is overcurrent, the tube voltage drop VCE will increase with the increase of the short-circuit current. When the IGBT is increased to a certain value, the detection diode DB will conduct reverse conduction. The reverse current signal is sent to the CPU processor via the IGBT drive protection circuit, and the CPU blocks the IGBT output for protection. If the detection diode DB is damaged, Cornwall inverter will appear ER15 fault, and the detection diode can be replaced to eliminate the fault.
(6) Fault ER11
The ER11 fault of Convo invertor indicates that the inverter is overheated. Possible causes are: air duct obstruction, high ambient temperature, damage to the cooling fan, and abnormal temperature detection circuit. When processing on-site, first judge whether the inverter is actually overheated. If the temperature is too high, you can first solve the fault according to the above reasons. If the inverter temperature is normal and there is an ER11 alarm, the cause of the fault is the fault of the temperature detection circuit. The seven-unit inverter module adopted by Comvo 22kW and below has internal temperature components. If this part of the circuit inside the module fails, ER11 alarm will also appear. On the other hand, the same fault phenomenon will occur when the temperature detection operation circuit is abnormal.