An IGBT (insulated-gate bipolar transistor) is a power semiconductor switch that turns large currents on and off thousands of times per second. In power electronics it is used to convert electricity from one form to another, for example AC to DC or one DC voltage to another. In EV charging, IGBTs mainly sit inside DC fast chargers and the car’s own power electronics. A typical AC wallbox does not convert power, so it relies on relays rather than IGBTs.
Key Takeaways
- An IGBT is a high-power semiconductor switch used to convert electricity.
- In EV charging, IGBTs mainly appear in DC fast chargers and vehicle power electronics.
- AC wallboxes use relays; the car’s onboard charger converts AC to DC.
- For DC chargers, ask about module efficiency, cooling and field replacement.
What Is an IGBT?
An IGBT combines two transistor types. Its gate works like a MOSFET’s: a small voltage controls it, so it is easy to drive. Its main current path works like a bipolar transistor’s, which lets it carry high current at high voltage with modest conduction losses. The result is a switch that handles hundreds of volts and many amps while being controlled by a low-power signal from a microcontroller.
IGBTs are usually packaged as discrete parts or as modules that hold several switches and diodes on one base plate, mounted on a heat sink.
What Is an IGBT Used For in Power Electronics?
Power electronics is the field of converting and controlling electrical power with semiconductor switches. IGBTs appear wherever medium to high power must be converted efficiently:
- Motor drives and inverters in industrial equipment and vehicles.
- Solar and storage inverters that turn DC into grid AC.
- Power supplies and rectifier stages in DC fast chargers.
- Uninterruptible power supplies and welding equipment.
According to the U.S. Department of Energy, vehicle power electronics include inverters, DC/DC converters and chargers, and today’s designs are largely silicon-based, with wide bandgap materials such as silicon carbide under active development.
IGBTs in DC Fast Chargers vs AC Wallboxes
The role of power semiconductors depends on where AC is turned into DC. Our explainer on whether EV chargers are AC or DC covers this in more depth.
| Charger type | Where AC becomes DC | Main switching parts | Typical power (DOT) |
|---|---|---|---|
| AC wallbox (Level 2) | Inside the car’s onboard charger | Relays or contactors, control board, residual current sensing | 7–19 kW |
| DC fast charger | Inside the charger cabinet | Power modules using IGBTs or MOSFETs (silicon or silicon carbide) | 50–350 kW |
In a DC fast charger, power modules rectify grid AC, correct the power factor and then use a DC/DC stage to match the battery’s voltage. The switches in those stages may be IGBTs or MOSFETs; the choice depends on voltage, switching frequency, cost and efficiency targets. Read how DC fast chargers work for the full chain.
What It Means for Buyers
For an AC charger buyer, IGBTs are not a spec to compare, because the unit does not contain a power converter. Focus on relay quality, protection and certification instead. For DC charger buyers and distributors, the power module design affects efficiency, heat, noise from fans and long-term reliability. Ask suppliers about module efficiency, thermal design, rated operating temperature and how modules are replaced in the field. These items also drive OEM unit cost.
EVDANCE builds both types. The EV-RHDC30K-L compact DC fast charger delivers 22 kW DC with OCPP 1.6J, while the EV-ACT3204PE 22 kW wallbox is an AC unit for homes and businesses.
Frequently Asked Questions
Is an IGBT the same as a MOSFET?
No. Both are voltage-controlled switches, but an IGBT conducts like a bipolar transistor and suits high voltage and current at moderate switching speeds. MOSFETs generally switch faster.
Does my home wallbox contain IGBTs?
Generally not in the power path. An AC wallbox passes grid AC to the car through relays; the car’s onboard charger does the conversion.
Why do IGBTs need heat sinks?
Every switch loses some energy as heat when it conducts and switches. Heat sinks, fans or liquid cooling keep the device within its rated temperature.
Related Reading
- How Do Home EV Chargers Work?
- Why Is DC Fast Charging So Expensive?
- How Fast Is a DC Fast Charger?
- Level 1 vs Level 2 vs DC Fast Charging
