Feature: Automotive
Figure 2: Onboard charger topology
Onboard DC/DC converters For an electric vehicle’s onboard DC/ DC converter, the efficiency and high power density of GaN and SiC can both make a good choice, depending on the application requirements. A BEV will typically have a high
voltage battery (400V or 800V) and a low voltage system (12V or 48V). To convert efficiently between high and low voltages, a bidirectional converter is usually required. A car using 48V as its main low voltage system may also use multiple 48V-to-12V DC/DC converters, enabling a 12V supply to be obtained locally, where needed for specific components, and therefore avoiding long, redundant cabling runs to carry 12V power.
Traction inverters Traction inverters convert DC power from the battery to AC to drive the vehicle’s electric motors. Although it offers excellent performance, GaN is typically only suited for applications up to around 650V. Where higher voltages are needed, such as in a typical EV traction inverter, then silicon or SiC is more suitable. SiC is oſten the preferred choice, due to its higher efficiency than silicon, as well as enabling smaller and lighter devices.
Moving to SiC raises some design
challenges that need addressing, including the extra engineering effort needed to adapt to a new technology. SiC devices’ high frequency switching can create problems with noise and electromagnetic interference (EMI), which require careful PCB layout, as well as parasitic inductances. Thermal management can also be difficult, with SiC’s high power density making heat dissipation tricky, particularly in compact spaces.
Traction motors and regenerative braking Smaller vehicles such as e-bikes need light, compact and efficient power systems, to provide the longest possible range from a battery, or to enable the use of a smaller battery while maintaining range at the same value. For example, e-bikes typically use a brushless DC (BLDC) motor, which is small enough to build directly into the wheel hub and often rated below 750W. To control the motor, an integrated chipset can be used, which includes a microcontroller, gate driver and multiple power MOSFETs.
24 October 2025
www.electronicsworld.co.uk Power semiconductors in traction
motors also play a vital role in regenerative braking systems. They need efficient, fast-switching semiconductors to capture and convert the vehicle’s kinetic energy into electrical energy, which is then stored in the battery for re-use. GaN-based devices can provide
the excellent efficiency and compact size needed for these applications, but do create new design challenges. Similarly to SiC, they can raise issues around noise and EMC, parasitic inductances and heat dissipation.
Expert advice across a broad portfolio Choosing the right components and the best semiconductor material for e-mobility applications depends on multiple considerations, including efficiency, power density, cost- effectiveness and reliability. Avnet Silica’s power semiconductor
portfolio supports e-mobility across a range of components, including DC-DC converters, power MOSFETs and IGBTs, power management ICs, WBG semiconductors (GaN and SiC), and battery management systems.
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