IGBT Module Routine Maintenance and Repair Tutorial

The application of the IGBT module rectifier in the frequency conversion circuit can not only realize the "controllable" rectification goal in the frequency conversion circuit, but also realize the energy feedback of the circuit. Therefore, the rectifier application based on the IGBT module has become the main form of the new "four-quadrant" frequency conversion circuit rectifier. However, in the actual use of the rectifier, the problem of IGBT module failure is also the main problem affecting the use of the circuit. Common IGBT module types are shown in Figure 1.

Figure 1 : Common IGBT Module Types

1. IGBT module overcurrent damage repair

Avoid lock-in effect

When the IGBT is damaged by the locking effect, in addition to replacing the damaged parts, the technicians should timely maintain and repair the parts of the drain current in the circuit design. First, moderately increase the driving resistance RG in the circuit to reduce di/dt of the IGBT component. Second, in order to avoid the locking effect caused by low driving voltage during operation, negative bias voltage can be used in the module design to improve the safety of the rectifier.

Setting of current limiting circuit

In order to avoid overcurrent damage to the module, designers should configure a current limiting circuit (RTC circuit) for the rectifier to avoid overcurrent damage. The process is shown in Figure 2.

D5 is a low temperature drift voltage comparator LM2903. By adjusting the resistance of R1 and R2, the required threshold voltage Vth can be obtained at the pin 2 of D5. When the IGBT is working normally, the voltage of pin 3 of D5 is lower than Vth, and the output of the comparator is low level. Since the output of the comparator is the output of the OC gate of the triode, the voltage of the DESAT terminal is clamped at a low level of about 0 V, and there is no overcurrent A fault occurs; when the VCE of the IGBT rises due to over-current and the voltage of pin 3 of D5 is higher than Vth, the comparator flips and outputs a high level, the OC gate is turned off, and the voltage of the DESAT terminal rises to + 15 V, exceeding the 6. 5 V compare threshold, overcurrent fault occurs.

2. IGBT module overvoltage and electrostatic damage

Module overvoltage damage fault repair method

In addition to replacing damaged parts during system overvoltage fault maintenance, voltage clamping technology should also be used on vulnerable parts to avoid damage to modules caused by overvoltage shocks.

IGBT rated voltage = US*K1*K2*K3

Formula 1: Calculation formula of module rated voltage

Where US is the peak voltage of the AC power supply; K1 is the grid voltage fluctuation coefficient K1, 1.15; K2: the pumping voltage K2 when

the DC intermediate circuit has feedback, 1.2; K3: the necessary voltage safety factor K3, 1.3~1.5.

Preventive measures for module electrostatic damage

The main preventive measures include the following main contents:

(1) During rectifier testing or installation and removal of IGBT modules, technicians should try to avoid touching the IGBT drive terminals with their hands. If it is necessary to touch, the electrostatic discharge should be completed before touching the module terminals.

(2) Before the anti-static wiring is completed, do not use conductive materials to touch the drive terminals of the IGBT module.

(3) During module testing, installation and other operations, try to operate under the condition that the bottom plate is well grounded.

3. The IGBT module is overheated and damaged

In the use of the rectifier, the equipment is often in a high temperature state. In order to prevent the rectifier IGBT module from overheating, derating should be used in the design to improve the heat dissipation capacity of the module. These methods mainly include the following measures: enlarging the heat sink of the module and ensuring that the heat sink is tightly connected to the module; applying heat-conducting glue between the heat sink and the module; Over-temperature protection should be set during installation, and the module circuit will be stopped directly when the temperature is too high, and a high-temperature alarm will be issued.

4. Maintenance of IGBT modules

Regular inspection: Regularly check the appearance and connection of the IGBT module to check for damage, looseness or corrosion. Make sure the heat sink and other cooling components are clean and free of dust to maintain good cooling performance.

Temperature monitoring: During use, pay close attention to the operating temperature of the IGBT module to ensure that it operates within a safe temperature range. Excessive temperature may lead to module overheating, performance degradation or even damage. Installing temperature sensors and over-temperature protection can help prevent such problems.

Electrical parameter detection: Regularly check the electrical parameters of the IGBT module, such as voltage, current, switching frequency, etc., to ensure that it operates within the normal range. If abnormal parameters are found, stop using it immediately and carry out fault diagnosis.

Fault diagnosis: When a fault occurs, determine the cause of the fault by analyzing the fault phenomenon and detecting relevant electrical parameters. Possible causes of failure include damaged components, improper circuit design, and control system failure. Take corresponding maintenance measures according to the cause of the failure.

Replacement of damaged parts: If the components in the IGBT module are found to be damaged, the corresponding components should be replaced according to the equipment manufacturer's recommendation. Be sure to use original or certified replacement parts to avoid further damage to the device.

Moisture-proof and dust-proof: ensure that the IGBT module operates in a dry and dust-free environment. Moisture and dust can cause problems with the electrical connections inside the module, affecting performance and longevity.

Regular maintenance: Perform regular maintenance according to the equipment manufacturer's recommendations to ensure the stable operation of the IGBT module. Regular maintenance may include cleaning, inspection, tuning, and firmware upgrades.

ESD protection: IGBT modules may be sensitive to electrostatic discharge (ESD), so appropriate anti-static measures should be taken during operation and maintenance. This includes using antistatic gloves, antistatic floor mats, and antistatic tools to reduce the risk of damage to modules from electrostatic discharge.

Safe operation: When performing IGBT module maintenance work, be sure to follow relevant safety regulations to ensure the safety of operators and equipment. Avoid performing repairs while the power is on, and make sure to operate after disconnecting the power supply. Also, use insulated tools and wear protective equipment.

Keep records: In order to better track the operation status and repair history of IGBT modules, it is recommended to establish detailed maintenance and repair records. This helps to discover potential problems in time, improves maintenance efficiency, and provides a reference for future fault diagnosis.

Training and Support: Ensure that operating and maintenance personnel are properly trained to properly handle issues related to IGBT modules. When encountering complex or unfamiliar faults, seek support from equipment manufacturers or professional maintenance service providers in time.

Follow manufacturer recommendations: Always follow the equipment manufacturer's recommendations and regulations when performing maintenance and repairs on IGBT modules. This helps ensure that equipment is functioning as designed and avoids unnecessary damage and accidents.