The dual carbon goal is accelerating the development of electric vehicles. The innovation of semiconductor technology helps the transition of vehicles from fuel vehicles to electric vehicles. The new generation of semiconductor material silicon carbide (SiC) will change the future of electric vehicles due to its unique advantages. The use of SiC in the drive inverter can meet higher power and lower energy efficiency, longer battery life, lower losses and lower weight, and its advantages can be more fully utilized in the trend of migrating to 800 V, but it is faced with cost, Packaging and technology maturity and other challenges. ON Semiconductor provides leading smart power solutions and has a deep history in the SiC field. It is one of the few suppliers in the world that can provide end-to-end SiC solutions from substrates to modules. Its innovative VE TracTM Direct SiC The VE-TracTM B2 SiC solution uses stable and reliable planar SiC technology, combined with sintering technology and die-casting mold packaging, to help designers solve the above challenges, and cooperate with the company’s other advanced smart power semiconductors to accelerate market adoption of electric vehicles and help future transportation. Towards sustainable development.

The development trend of electric vehicle main drive

Regardless of the configuration of the electric vehicle, whether it is fully battery driven or a series plug-in or parallel hybrid drivetrain, vehicle electrification has several key elements: First, the power is stored in the battery, and then the direct current is converted by the inverter to The AC output is converted into mechanical energy for the motor to drive the car. Therefore, the energy efficiency and performance of the main drive inverter is the key, which will directly affect the performance of the electric vehicle and the achievable driving range per charging cycle.

The main driver of electric vehicles pursues higher power, higher energy efficiency, higher bus voltage, lighter weight and smaller size. More power means greater continuous torque output and better acceleration performance. Higher energy efficiency enables longer battery life and lower losses. 400 V batteries are the current mainstream and are about to develop to 800 V. The 800 V architecture reduces charging time and losses and reduces weight, resulting in longer range. Whether the motor is on the front or rear axle, the smaller motor size makes more trunk and passenger space available. These trends have driven the transition from IGBTs to SiC power devices in the main drive of electric vehicles.

SiC is the future of main drive inverters

One of the most important properties of SiC is that its band gap is wider than that of Si, and its electron mobility is three times that of Si, resulting in lower losses. The breakdown voltage of SiC is 8 times that of Si, the high breakdown voltage and thinner drift layer are more suitable for high voltage architectures such as 800 V. The Mohs hardness of SiC is 9.5, which is only slightly softer than diamond, the hardest material, and 3.5 harder than Si. It is more suitable for sintering. After sintering, the reliability of the device is improved and the thermal conductivity is enhanced. The thermal conductivity of SiC is 4 times that of silicon, making it easier to dissipate heat, thereby reducing heat dissipation costs.

At the inverter level or at the vehicle level, SiC MOSFETs can achieve lower overall system-level cost, better performance and quality than IGBTs. The key design advantages of SiC MOSFETs over IGBTs in main drive inverter applications are:

• SiC enables higher power density per unit area, especially at higher voltages (eg 1200 volt breakdown)

• Lower conduction losses at low currents, resulting in higher energy efficiency at low loads

• Unipolar behavior for higher temperature operation and lower switching losses