The European Union remains committed to its 2035 zero-emission target, effectively banning the sale of new petrol and diesel internal combustion engine vehicles. This accelerates the transition from fossil fuels to electric vehicles (EVs). However, driving range remains a key concern for consumers. To attract buyers, EVs must offer sufficient range, support fast charging, and be affordable. Consequently, automotive semiconductor technology needs continuous advancement to meet demands for higher efficiency, power density, and reliability. Silicon Carbide (SiC) semiconductors, particularly MOSFET devices used in core components like electric drive systems, are pivotal technologies for significantly enhancing power electronics performance and are becoming a major focus for semiconductor manufacturers.
In high-voltage applications, SiC MOSFETs outperform traditional silicon devices, offering higher efficiency, faster switching speeds, and lower thermal losses. This technology enables traction inverters and onboard chargers (OBCs) to achieve more compact module designs while maintaining high efficiency and peak power, thereby reducing overall vehicle weight and improving space utilization.
Onsemi EliteSiC MOSFET Technology Evolution
Onsemi SiC MOSFET with High-Performance Gate Driver
SiC MOSFETs are demonstrating strong technical advantages in critical EV power electronics applications, gradually replacing traditional silicon (Si) MOSFETs, diodes, and Insulated Gate Bipolar Transistors (IGBTs). While IGBT technology remains widely used in mid-to-low-end EVs due to its cost-effectiveness, SiC devices offer significant performance gains, primarily through their much higher switching frequency. Compared to traditional devices, SiC MOSFETs effectively reduce conduction and switching losses, substantially boosting overall system efficiency. Their superior material properties also enable higher power density and current density, providing better solutions for EV powertrain design.
Using Onsemi's EliteSiC MOSFET technology, developers can build 22 kW OBC power stages supporting 800 V high-voltage battery platforms. The technology is equally suitable for High-Voltage to Low-Voltage (HV-LV) DC-DC converters, whose core function is efficiently and stably converting high-voltage DC from 400 V or 800 V traction batteries to the 12 V DC required by the vehicle's low-voltage network. Crucially, to fully unleash the inherent performance potential of SiC MOSFETs, other key system components—especially the gate driver—must be specifically matched and optimized for SiC's high switching speed and high-frequency operation, a critical step for achieving optimal system performance.
Traction Inverter: The Core of Power Conversion & Market Outlook
As a core component of the EV powertrain, the traction inverter performs the critical task of converting DC from the battery to AC for the traction motor. It is precisely in this vital area that SiC devices are steadily displacing the long-dominant IGBT technology. Market research firm IDTechEx clearly outlines this trend: by 2035, SiC MOSFETs will become the absolute mainstream technology in the EV traction inverter market. These high-performance inverters demand components rated for high voltages (600 V to 1200 V) and capable of peak phase currents up to 200 A to support broad power requirements ranging from 50 kW to 250 kW and beyond.
IDTechEx projections further reveal the immense growth potential of the entire EV power electronics market. By 2035, the global market size is expected to climb to a staggering $36 billion. Between 2025 and 2035, the market is forecasted to achieve a Compound Annual Growth Rate (CAGR) of 17%, highlighting the EV industry's strong demand and continuous investment in efficient power electronics, particularly SiC solutions.
Gate Drivers: Key to Unleashing SiC Performance
In high-performance power electronics systems using SiC MOSFETs, achieving optimal efficiency requires isolated gate drivers with high peak source/sink current capabilities. The gate driver acts as the "commander" of the power transistor, directly controlling the switching speed of the SiC MOSFET by providing the fast, precise gate drive voltage (VGS) and instantaneous high current needed for turn-on and turn-off. This precise, fast driving capability is decisive for effectively reducing switching and conduction losses during high-frequency operation, forming the core element for enhancing overall system efficiency.
Dedicated gate drivers not only supply the necessary driving energy but also integrate the essential electrical isolation barrier between the low-voltage control side and the high-voltage power stage. By providing robust electrical isolation, independent Undervoltage Lockout (UVLO), and multiple fault protection mechanisms (such as overcurrent, short-circuit, and overtemperature protection), these drivers significantly enhance system reliability, circuit robustness, and operational safety, providing solid protection for the complex and demanding EV operating environment.
Onsemi NCV51752 Solution: Integrated Negative Bias Control
Onsemi's NCV51752 is a single-channel isolated gate driver specifically designed for driving SiC MOSFETs, with the core mission of ensuring fast and extremely reliable switching. It features outstanding performance parameters, including an ultra-short 36 ns propagation delay and high dV/dt immunity of up to 200 V/ns. These characteristics enable it to effectively handle the high-frequency, high-voltage challenges of SiC systems, significantly boosting performance. Notably, the NCV51752 integrates negative bias control and offers high isolation voltage, enhancing reliability and safety.
As high-speed switching devices, SiC MOSFETs generate extremely high voltage slew rates (high dV/dt) during switching transitions. This high dV/dt can induce unintended parasitic turn-on (also known as "Miller turn-on") through the MOSFET's inherent Miller capacitance (C_GD), leading to spurious conduction, losses, and potential damage. The NCV51752's integrated negative bias mechanism pulls the SiC MOSFET's gate-source voltage (V_GS) below 0V (i.e., applies a negative voltage) during the off-state. This negative voltage effectively raises the gate turn-on threshold, fundamentally eliminating the possibility of parasitic conduction due to the Miller effect and ensuring stable off-state operation. A significant advantage is that this negative bias function is internally integrated, eliminating the need for an external negative power rail, thus simplifying design and effectively reducing overall system costs.
Conclusion
Combining SiC MOSFET technology and high-performance, intelligent gate drivers (such as the NCV51752 with integrated negative bias control) profoundly revolutionizes EV power electronics system architecture. Together, they deliver unprecedented high efficiency, faster switching speeds, and superior overall system performance. As the global EV market continues its rapid expansion, these advanced power electronics technologies will play an indispensable role in meeting consumer expectations for longer range, faster charging, and stronger power, while complying with increasingly stringent efficiency and emission regulations. They are not only the focus of current technological competition but also the core driving force propelling us towards a cleaner, more efficient, and sustainable future of transportation.