Because IGBTs are bipolar switching devices that use conductivity modulation, they exhibit slower switching speed, particularly longer turn-off time at high temperature, than unipolar MOSFETs. Therefore, IGBTs cause higher switching losses.
In contrast, IGBTs have advantages in that they can easily achieve high withstand voltage and have relatively low on-state voltage even at high current and high temperature.
Therefore, IGBTs and MOSFETs fabricated using silicon material have the following application areas:
- MOSFETs: Low-voltage applications (below 200 to 300 V)
- IGBTs: High-voltage applications (above 1200 V)
- IGBTs and MOSFETs are used for different purposes for 400- to 1200-V applications:
(1) IGBTs are used for inverter applications with a switching frequency of less than 20 kHz requiring high overload endurance.
(2) MOSFETs are used for inverter applications with a switching frequency exceeding 20 kHz.
(3) MOSFETs are used for some low-capacity inverter applications whereas IGBTs are used for soft-switching and high-current-density applications. IGBTs and MOSFETs should be used properly according to their characteristics.