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The novice can solve the frequency converter common fault diagnosis and processing.(1)
- May 02, 2018 -

1.1 damage to the inverter power module.

1.1.1 judgment

The inverter power module mainly includes IGBT, IPM, etc., to check whether the appearance has been blown up, and whether the terminal and the attached printed board have ablation marks.Using a multimeter to check the C - E, G, C, G - E is general, or use the multimeter to measure P for U, V, W and N for U, V, W resistor is inconsistent, and the driving power device control of U, V, W, P, N the resistance of the inconsistent, which is to determine the damage to the devices.

1.1.2 cause of damage.

(1) the device itself is of poor quality.

(2) the external loads are severe over current, imbalance, a motor phase winding of short circuit, a phase winding internal short circuit, mechanical load gets stuck, breakdown, and have a short circuit or to ground short circuit output wire.

(3) the capacitance is connected to the load, or the capacitance is too large due to improper wiring, so that the power tube has an impact current.

(4) the user network voltage is too high, or there is a strong transient overvoltage, causing overvoltage damage.

(5) the over-voltage absorption circuit of the power switch tube in the machine is damaged, resulting in the failure to effectively absorb the overvoltage and damage the IGBT, as shown in figure 1.

(6) the filter capacitance is aging, the capacity is reduced or the internal inductance becomes larger, and the over-voltage absorption capacity of the bus is decreased, causing too high voltage on the bus to damage IGBT.When the overvoltage on the bus is switched off by the inverter switch, the inductive energy storage of the bus circuit changes.

(7) or IGBT IPM power device of the front-end photoelectric isolating device power device breakdown, caused by breakdown or in PCB isolation device has a spark breakdown caused by dust, moisture, cause the damage of IGBT, IPM.

(8) improper operation or defects in the product design software, which can lead to the instantaneous simultaneous conduction of the upper and lower power switch devices under the unstable conditions such as interference, startup and shutdown.

(9) lightning strikes, leakage of houses, entry of foreign bodies, accidental collision of inspectors, etc.

(10) the filter capacitor is replaced by maintenance, because of the poor quality of the capacitor, or the line with the capacitance is longer than before, which increases the inductance, causing a significant increase in the overvoltage of the bus.

(11) the front grade rectifier bridge was damaged due to the incoming alternating current at the front stage of main power supply, which caused damage to IGBT and IPM.

(12) repair and replace the power module, because there is no electrostatic protection, IGBT is damaged during welding operation.Or because of the heat dissipation, fastening, insulation and so on in the repair is not good, resulting in short-term use and damage.

(13) using IGBT in parallel, the consistency of the model and batch number is not considered in the replacement, resulting in the current unevenness and damage of each parallel element.

(14) a component of the inverter's internal protection circuit (overvoltage, overcurrent protection) is damaged and the protection function is lost.

(15) a set of power supply in the inverter, especially IGBT drive level + and - power failure, change the output value or the insulation between the two sets of power supply is broken.