Problems that should be paid attention to when the inverter is running abnormally during maintenance work - Database & Sql Blog Articles

Brand AVX TPSE226M035R0125 Low impedance tantalum capacitor AVX 22

Filter 18.432M

From the six PWM output terminals of the CPU to the intermediate buffer circuit, it is called the inverter pulse pre-stage circuit, and the drive circuit is called the inverter pulse post-stage circuit, collectively called the inverter pulse circuit.

Fault status:

1. The starting operation is normal, the operation display panel has a normal output frequency indication, but there is no three-phase output voltage;

2. The starting operation is normal, the operation display panel has a normal output frequency indication, and the output three-phase voltage is unbalanced;

3. When the start button is pressed, the OC fault is skipped;

4. Occurrence of OC failure during operation;

5, light load operation is normal, the load motor jumps or jumps OC fault.

The essence of the fault and the maintenance idea (corresponding to the five states of the fault state):

1. There are several factors: a, the +5V power supply on the input side of the driver circuit optocoupler is lost; b, the buffer of the pre-stage pulse circuit is damaged; c, the relevant control signal of the CPU is uncertain or the relevant control pin is damaged; d. The fault protection circuit is malfunctioned, so that the pulse pre-stage circuit is locked by the fault signal.

It is important to note here that the pre-stage circuit of the inverter pulse signal, such as the tri-state flip-flop, the buffer circuit, etc., may be directly controlled by the voltage and current detection and protection circuit. When the protection circuit is malfunctioned, the clamp is clamped. And blocked the transmission of six pulse signals. There is a concept that the fault protection circuit is solely involved in the pulse transmission control. Although the failure rate caused by a and b is better, the causes caused by c and d often constitute difficult faults. The maintenance ideas can't be here, and the repairs can be detoured.

2. There are the following three factors: a. The optocoupler of the drive circuit is damaged, and the inverter pulse signal cannot be transmitted normally; b, the internal resistance of the inverter module becomes large, and the three upper arm IGBT modules have poor conduction, so The three-way drive circuit may not have an IGBT tube voltage drop detection circuit, so it cannot report an OC fault; c, the pulse pre-stage circuit or the CPU inverter pulse output pin is defective, resulting in one or two inverter pulses missing.

Do not focus on the rear drive circuit, or the inverter pulse of the previous stage is not added to the drive circuit. In particular, it is necessary to have a concept that the module is defective and the internal resistance of the inverter module becomes large. Without considering the factors of c, it constitutes a difficult fault.

3, have the following factors: a, the latter drive circuit itself is poor; b, the drive circuit power supply, with load capacity is insufficient, such as filter capacitor loss of capacity, rectifier diode is inefficient (forward resistance becomes larger, reverse resistance becomes smaller) ); etc., the inverter module is defective.

The dynamic and static detection (voltage detection) of the drive circuit may be normal, and the current output capability of the drive circuit should be tested. Pay attention to the factors of b and c.

4. There are several factors: a, the load capacity of the drive circuit, the conduction internal resistance detection of the inverter module; b, the three-phase output current detection circuit; c, the reference voltage circuit in the fault detection circuit. d, the reasons for user load.

Pay attention to the factors affecting b, c, and d. The three-phase detection circuit itself is bad, the working point shifts, and the OC fault may be falsely reported; the reference voltage offset in the fault detection circuit causes the current detection to be inaccurate, and the OC fault is falsely reported; the inspection is no problem, and the production site is found. It does not rule out the problem of load. b, c factors, may enter the scope of difficult faults.

5, there are three factors: a, the drive circuit's current (power) output capacity is insufficient; b, the inverter module is poor, the conduction internal resistance is too large; c, the load circuit has problems, the motor is broken, not the inverter problem .

The inverter is not working properly. It is not necessarily the problem of the inverter. It is recommended that the user try another motor. Factors such as b and c should be considered, and sometimes factors other than the inverter should be considered.