How SiC Is Enabling Next Generation Automotive Power Electronics
Key Highlights
- Silicon carbide (SiC) wide bandgap semiconductors enable higher switching frequencies and lower power losses in EV power electronics, improving overall system efficiency.
- SiC devices support the design of smaller, lighter, and more thermally efficient on-board chargers, helping manufacturers meet space and weight constraints.
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By Vladimir Halaj, Technical Marketing Analyst, onsemi, for Mouser Electronics
EV Power Electronics Challenges and the Role of SiC
Electric vehicles (EVs) impose strict and often competing constraints on power electronics design. Limited installation space, weight targets, efficiency requirements, thermal limits, safety standards, and cost-reduction pressure must all be addressed simultaneously within a vehicle platform expected to operate reliably for many years. As EV architectures evolve toward higher battery voltages and increased onboard power, managing these trade-offs becomes one of the central challenges for OEMs and Tier-1 suppliers.
Silicon carbide (SiC) has emerged as an important wide bandgap (WBG) enabler for addressing these challenges in high-voltage (HV) power electronics. While conventional Si super-junction MOSFETs and IGBTs have served automotive applications well for decades, they show limitations in some applications as power levels rise. These trade-offs affect modern EV performance targets, and they include higher switching losses and constraints on switching frequency set by semiconductor physics, as well as increased cooling overhead and the resulting penalties in size and weight.
These challenges are most visible in the vehicle’s HV power conversion stages, where energy must be converted efficiently between AC and DC or between different DC voltage levels. One such subsystem is the On-Board Charger (OBC), an essential component in every battery electric vehicle. The OBC converts AC power from the grid into DC power suitable for charging the HV battery pack, while operating under tight constraints on efficiency, power density, thermal performance, and electromagnetic compatibility.
OBC requirements vary by vehicle class and regional infrastructure. Premium EVs target onboard charging power of up to 22kW to reduce charging time, driving higher design stress and more complex thermal solutions. EVs in the mid‑price range typically target 11kW, offering more flexibility in power conversion topologies and electronic components selection, thus providing more options between cost and performance. By enabling higher switching frequencies, significantly lowering power losses, providing a low reverse recovery body diode, and improving thermal performance, SiC devices expand the OBC design space. This allows designers to reduce the size of magnetics and passive components, simplify thermal management, and improve overall system efficiency. To support EV performance targets, onsemi offers a broad portfolio of automotive-qualified SiC solutions for OBCs and other high-power EV subsystems. These solutions include discrete SiC MOSFETs, diodes, and integrated power modules that allow designers to scale performance, optimize layout, and meet automotive reliability targets.
OBC Architectures: Power Stage Topologies and Semiconductors
Conventional OBCs are typically implemented as two-stage power converters, consisting of a bridgeless PFC stage followed by an isolated DC-DC stage, commonly based on LLC or CLLC resonant topologies. As EV platforms transition to 800V battery architectures and higher onboard charging power, these stages require SiC devices rated up to 1200V and capable of higher frequency operation.
To support OBC designs in the 11kW to 22kW range, onsemi offers SiC APM32 power modules optimized for both PFC and DC-DC stages. For example, 3‑phase bridge modules, such as the NVXK2VR40WXT2 (1200V, 40mΩ), are well suited for bridgeless PFC implementation, while full-bridge and dual half-bridge modules like the NVXK2TR40WXT address the demands of faster DC-DC conversion (Figure 1). These modules are automotive qualified under AEC-Q101, AQG-324, and meet creepage, clearance, and reliability IEC standards, supporting robust OBC designs in demanding vehicle environments.
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Author Bio
Vladimir is a technical marketer at onsemi specializing in automotive and power electronics solutions. He brings a background in electronics and hardware design and holds a university degree in electrical engineering, specializing in electronics and photonics.
