SiC MOSFETs have attracted a lot of attention due to their unique advantages such as high voltage tolerance, high frequency tolerance, and high temperature tolerance. Short circuits are a common issue in electronic applications, so today, VBsemi will delve into the short circuit detection of SiC MOSFETs.

There are two common types of short circuits in SiC MOSFETs: soft-switching short circuits and load short circuit faults.

1. Soft-switching short circuit: During the switching operation, the switching device may fail to disconnect the current in time due to various reasons, leading to continuous current flow in the switching device, causing a short circuit.

2. Load short circuit fault: A short circuit suddenly occurs at the load end. This can be caused by load device damage, wiring errors, or external environmental factors. When a load short circuit occurs, the current will increase rapidly, causing the SiC MOSFET to overload and possibly damage it.

Causes of Short Circuits in SiC MOSFETs:

1. Overvoltage: Long-term exposure to voltages exceeding its rated voltage can cause insulation breakdown or oxide layer rupture.

2. Overcurrent: The SiC MOSFET is broken down by a current larger than its rated current, causing damage to the internal structure of the power transmission channel and causing a short circuit.

3. High temperature: When the SiC MOSFET operates at a temperature exceeding its allowed range, the high temperature can cause thermal expansion of materials and electron migration, leading to a short circuit.

4. Design issues: Improper material selection, excessive voltage and current, and inappropriate electrode gaps can all cause short circuits.

Short Circuit Detection and Protection for SiC MOSFETs:

1. Short circuit detection method: Current detection technology can be used to achieve short circuit detection.

For example, using a Hall sensor or current transformer to detect current changes.

When the current exceeds a set threshold, a short circuit fault can be determined.

2. Short circuit protection technology: After detecting a short circuit fault, take protective measures:

• Use overcurrent protection circuits to cut off the current to prevent damage to the device due to excessive current.

• Use temperature protection circuits to monitor the chip temperature and automatically cut off the current when the temperature exceeds a set value.

• Use short circuit protection circuits to monitor the rate of current rise. When the current rise rate is too fast, it can be judged as a short circuit fault and protected.

3. Short circuit shutdown strategy: When a short circuit fault occurs, choosing to quickly shut down the SiC MOSFET can avoid damage. By using the appropriate shutdown circuit, a fast shutdown time can be achieved to improve the effectiveness of short circuit protection.

4. Other protective measures: Use current limiting technology to limit the current to prevent damage from excessive current. When designing the circuit, consider the layout and heat dissipation design of the circuit to improve the short circuit tolerance of the SiC MOSFET. Of course, choosing SiC MOSFET products with better performance is also very important.

SiC MOSFETs use silicon and wide bandgap technology, offering advantages such as greater power efficiency, smaller size, lighter weight, and lower overall cost. They are suitable for high voltage scenarios above 600V, including photovoltaics, new energy vehicles, charging stations, wind power, rail transit, and other power electronics fields.