IGBTs (Insulated-Gate Bipolar Transistors) and MOSFETs (Metal-Oxide-Semiconductor Field Effect Transistor) are used in many different types of power applications, including renewable energy, aerospace, automotive and transportation, test and measurement, and telecommunications. At the design phase, these widely-used power transistors are often interchangeable, although MOSFETs generally work well for lower voltages and power, while IGBTs are well adapted to higher voltages and power. With the introduction of silicon carbide, MOSFETs are more effective than ever before, offering unique benefits compared to traditional silicon components.
MOSFETs have been around for many years and include designs that are silicon and silicon carbide-based. In general, MOSFETs are used with designs involving relatively lower voltage and power requirements. However, that is not always true when it comes to silicon carbide MOSFETs.
Silicon carbide MOSFETs have a critical breakdown strength that is 10x of silicon, and silicon carbide MOSFETs can operate at much higher temperatures, provide higher current density, experience reduced switching losses, and support higher switching frequencies. This also means that silicon carbide MOSFETs are more similar to silicon IGBTs, and in many designs, can replace silicon IGBTs while offering additional benefits to the design overall.
Silicon carbide MOSFETs outperform their silicon counterparts in other ways, including the ability to handle higher voltage and power requirements while still saving space. The use of silicon carbide makes these MOSFETs extremely rugged and durable.
IGBTs are used where there is a need for well-controlled, medium-speed switching, and they can be cheaper than comparable silicon MOSFETs. In addition, IGBTs can handle higher voltages than traditional MOSFETs, but that comes with high switching losses when silicon is used. Those losses generate heat, resulting in a need for costly and large thermal management solutions and a limitation on power-conversion system efficiency.
In fact, just the thermal management components required when a silicon IGBT is used will significantly increase both the size and weight of the system, which can be a serious issue for designs involving electric vehicles or aerospace applications. However, for lower switching speeds, IGBTs offer good efficiency and energy savings, which is why for many years they were preferred over comparable MOSFETs.
The excellent thermal conductivity of silicon carbide MOSFETs allows for better thermal conductivity and lower switching losses. The reduced switching losses alone (even at high voltages) mean far less heat generation, thus reducing the thermal management requirements of systems using silicon carbide MOSFETs as opposed to silicon IGBTs.
This, in turn, leads to lower overall costs as well as a far more compact, weight-saving design compared. In addition, silicon carbide MOSFETs are more rugged than silicon IGBTs, making them ideal for harsh environment applications that IGBTs would find challenging, such as onboard chargers for electric vehicles or solar power systems.
Overall, a wise approach would be to consider the use of silicon carbide MOSFETs when deciding what type of component to use for a design. Taking into consideration the high switching speeds, reduced switching losses, higher efficiency, and ruggedness of silicon carbide MOSFETs compared to their silicon IGBT counterparts, it is easy to see why more and more engineers are opting for silicon carbide power components. Silicon carbide offers more reliable, sustainable designs with better overall efficiency, a smaller footprint, and less weight.
