Why Is IGBT Fuse a Key Part of Circuit Protection?

IGBT (Insulated Gate Bipolar Transistor) is a semiconductor power switching device with high voltage, high current and high frequency characteristics. It plays an important role in the field of modern power electronics and is widely used in AC to DC power transmission, motor drive, power electronics regulation and other fields. The main function of IGBT fuse is to provide overcurrent or short-circuit protection for IGBT and related equipment in the circuit. The specific functions are as follows:

1. Overcurrent/short-circuit protection

Core function: When the current exceeds the safety threshold due to abnormal load (such as short circuit, overload) of IGBT, IGBT Fuse will quickly melt and cut off the current path to prevent IGBT from burning due to thermal breakdown or electrical stress. Response speed is key: IGBT failure may occur within microseconds, so fast-acting (semiconductor-specific) fuses are required. Their breaking speed is much faster than conventional fuses to ensure that the circuit is cut off before the device is damaged.

2. System-level protection

Protect peripheral circuits: prevent fault current from spreading to the power supply, drive circuit or other sensitive components, and reduce the risk of system-level damage. Cooperate with other protection mechanisms: provide redundant protection as a supplement to the built-in protection of IGBT (such as desaturation detection and overtemperature protection).

3. Selection points

Rated current: needs to be slightly higher than the normal working current of IGBT and lower than its maximum tolerance value.

Breaking capacity: needs to be higher than the maximum fault current that may occur in the system.

Voltage level: match the circuit working voltage to prevent continuous conduction due to unextinguished arc.

I2t value: the melting heat of IGBT Fuse needs to be lower than the tolerance limit of IGBT to ensure thermal protection priority.

4. Precautions

Cannot be relied on alone: ??it needs to be combined with absorption circuit (RC buffer, clamping diode), drive isolation, overvoltage protection and other designs.

Alternative solution: electronic insurance (such as fuse + current detection IC) may be used in some scenarios to achieve more accurate and fast shutdown.

Example scenario: In the inverter, if the motor stalls and causes IGBT overcurrent, the special fuse can be blown within milliseconds to protect the high-value IGBT module from replacement, while isolating the fault to avoid affecting the entire control system.

IGBT Fuse is a key line of defense to prevent power devices from being damaged under extreme currents, but it needs to be accurately selected and combined with a multi-level protection strategy to achieve reliable protection. Fuses can avoid more than 90% of the risk of overcurrent damage to motors at a cost lower than 1% of the circuit. Its simple and reliable physical characteristics make it always occupy an irreplaceable position in industrial electrical systems.