EV業界におけるSiCのメリット

As a wide-bandgap (WBG) semiconductor material, SiC's wider energy difference gives it higher thermal and electronic properties compared to traditional Si. This feature enables power devices to operate at higher temperatures, frequencies and voltages.

SiC's energy efficiency in electric vehicle applications and other electronic and electrical products is largely due to the material itself. Compared with Si, SiC has the following characteristics:

1. 10 times the dielectric breakdown field strength;

2. 2 times the electron saturation speed;

3. 3 times the energy band gap;

4. 3 times higher thermal conductivity;

In short, as the operating voltage increases, the advantages of SiC become more obvious. Compared with Si, 1200V SiC switches are more advantageous than 600V switches. This characteristic has led to the widespread application of SiC power switching devices, thereby significantly improving the efficiency of electric vehicles, their charging equipment and energy infrastructure, making SiC the first choice for car manufacturers and first-tier suppliers.

But in low-voltage environments of 300V and below, SiC’ s advantages are relatively small. In this case, another wide-bandgap semiconductor, Gallium Nitride (GaN), may have greater application potential.

Range and efficiency

A key difference of SiC compared to Si is its higher system-level efficiency, which is due to SiC' s greater power density, lower power losses, higher operating frequency and higher operating temperature. This means higher driving range on a single charge, smaller battery sizes and faster on-board charger (OBC) charging times.

In the world of electric vehicles, one of the biggest opportunities lies in traction inverters for electric drivetrains that are alternatives to gasoline engines. When direct current (DC) flows into the inverter, the converted alternating current (AC) helps the motor run, powering the wheels and other electronic components. Replacing existing Si switch technology with advanced SiC chips reduces energy losses in the inverter and enables vehicles to provide additional range.

Therefore, SiC MOSFET become a compelling commercial factor when characteristics such as form factor, size of the inverter or DC-DC module, efficiency and reliability become key considerations. Design engineers now have smaller, lighter, and more energy-efficient power solutions for a variety of end applications. Take Tesla for example. While the company's previous generations of electric vehicles used Si IGBT, the rise of the standard sedan market prompted them to adopt SiC MOSFET in the Model 3, an industry first.

Power is the key factor

SiC' s material properties make it a first choice for high-power applications with high temperatures, high currents and high thermal conductivity. Because SiC devices can operate at higher power densities, it can enable smaller form factors for electric vehicle electronic and electrical systems. According to Goldman Sachs, SiC’ s extraordinary efficiency can reduce the manufacturing and ownership costs of electric vehicles by nearly $2,000 per vehicle.

With battery capacity already reaching nearly 100kWh in some electric vehicles, and plans for continued increases to achieve higher ranges, future generations are expected to rely heavily on SiC for its added efficiency and ability to handle higher power. On the other hand, for lower-power vehicles such as two-door entry-level electric vehicles, PHEV, or light-duty electric vehicles using 20kWh or smaller battery sizes, Si IGBT are a more economical solution.

To minimize power losses and carbon emissions in high-voltage operating environments, the industry is increasingly favoring the use of SiC over other materials. In fact, many electric vehicle users have replaced their original Si solutions with new SiC switches, which further validates the obvious advantages of SiC technology at the system level.