Efficiency is increased in power semiconductors by using SiC, a wide bandgap technology.

Electric vehicles are being launched one after another worldwide due to environmental concerns. Driving range, a major drawback of electric vehicles, is also increasing. As a result, they have become competitive against internal combustion engine (ICE) vehicles.

An important measure of the success of electric vehicles is consumer acceptance. Given that the price of lithium-ion batteries is decreasing and regulatory support is available in various countries, consumers are more interested in increasing charging speed and reducing charging time than in the price of electric vehicles.

It takes less than five minutes to fill the fuel tank of an ICE vehicle. Electric vehicles take a long time to charge their battery packs, and there are also problems finding charging stations.

Then, what other methods can be used to increase electric vehicle charging speed? Efficient power delivery and increasing power levels are among the ways to speed up charging. Batteries are charged using a constant current method to prevent damage, but due to varying regulations across countries, increasing the current may be ineffective or even impossible. Furthermore, increasing the current can lead to wiring harness issues and increase the vehicle's weight.

Therefore, a realistically feasible solution is to increase the voltage to 400V or higher. By using silicon carbide (SiC), a wide bandgap technology, in power semiconductors, power can be efficiently transmitted at high voltages.

SiC is a broadband bandgap semiconductor that has emerged as a disruptive material capable of replacing silicon-based power switches (MOSFETs and IGBTs). Many automotive companies and charging system manufacturers are already adopting SiC. SiC has low losses, high efficiency, and can withstand high voltages. Therefore, as battery voltages in electric vehicles (over 400V) increase and power levels rise with onboard chargers (over 10kW) and offboard DC chargers (over 50kW), the use of SiC as a power semiconductor switch is increasing.

Due to its superior material properties, SiC has low losses and can operate at high voltages. As shown in Table 1, compared to silicon, it has lower on-resistance, higher thermal conductivity, enables high breakdown voltage, and has a faster saturation rate.

To fully utilize these characteristics, it is also important to understand how SiC power devices are driven. Controllers control switching on and off, enabling efficient power transfer across the entire power electronic circuit. A gate driver acts as the interface between the controller and the power device. The gate driver functions like an amplifier, taking the controller signal, amplifying it, and driving the power device.

Selecting a suitable gate driver is very important to utilize the outstanding characteristics of SiC FETs. This is because the requirements are different from when driving silicon MOSFETs or IGBTs.

At the APEC 2018 exhibition held in San Antonio, TI showcased a complete ecosystem using SiC solutions ranging from solar power to automotive charging. It presented a 6.6kW totem pole PFC reference design with 98.5% efficiency for HEV/EV onboard chargers, an automotive dual-channel SiC MOSFET gate driver reference design with 2-level turn-off protection, and a 10kW 3-phase 3-level grid-connected inverter reference design for solar string inverters.