Lighter, more efficient and space-saving drive systems are needed to boost the number of xEVs and to meet climate goals, such as carbon neutrality. The efficiency of the inverter in particular has an impact on the range and size of the battery. Developers are under pressure to come up with systems that are lightweight, highly efficient and simple to integrate.
SiC power electronics enables compact drives
Silicon carbide (SiC) has emerged as a key material for the next generation of power electronics. Modern SiC MOSFETs offer higher switching frequencies with lower losses and serve as a key enabler for more compact, efficient and easier-to-cool traction systems in vehicles.
Electric drives especially require high power density and reliable, yet simple heat dissipation. Although SiC is fundamentally efficient, power loss and thermal coupling must be specifically controlled to enable a compact design without any thermal limitations.
An example of this type of optimized solution is the TRCDrive pack module series from ROHM (Fig. 1). Two complete SiC half-bridges are combined in a 2-in-1 principle within a single module and enable particularly compact, powerful inverter systems.
Overview of the technical highlights:
- Fourth generation SiC MOSFETs (up to 1200 V/600 ARms per module)
- 2-in-1 half-bridges for particularly compact inverters
- Single-sided, highly efficient heat dissipation
- Top-side press fit pins that leave the underside completely free for thermal connections
- Low parasitic two-layer busbar structure (only 5.7 nH)
- Temperature range from -40 °C to +175 °C
Module variants are available in two package sizes (for various outputs and installation sizes) and with either a sintered silver surface or a pre-applied thermal conductive film. Both variants support single-sided heat dissipation and facilitate integration into the cooling system.
The available versions cover both 750 V and 1,200 V rated systems, making them ideal for integration into an array of vehicle architectures, from compact electric vehicles to powerful SUVs or light commercial vehicles.
Integrated drive with SiC module
A current example of the use of this module technology is the eAxle module from Valeo: The electric motor, inverter and reducer are combined in a shared packaging.
Thanks to the TRCDrive pack modules, single-sided, highly efficient heat dissipation is sufficient, and complex cooling architectures or double-sided contacting are no longer required.
The top-side press fit pins additionally facilitate system integration: All essential electrical signals are top-side connected, thereby leaving the heat-dissipating underside free for the cooling system. This results in a lower overall height, reduced weight and simplified interfaces for installation and servicing.
Due to the low parasitic inductance and high current density, the modules are ideal for modern platform architectures and flexible vehicle concepts. The high degree of modularity enables individual adaptation to various vehicle segments, ranging from compact electric cars to powerful SUVs or commercial vehicles.
The demonstrated system was designed for rear axle applications, among others. The compact integration of motor, inverter and reducer places increased demands on the EMC behavior and heat management. Exactly these requirements can be met efficiently with the selected module concept.
From evaluation to full-scale production
Two coordinated evaluation kits are available for practical development and rapid system integration (Fig. 2). The double-pulse testing kit can be used to characterize individual modules under realistic conditions, for example to analyze switching losses and dynamic behavior. It includes an optimized printed circuit board layout with gate driver, power routing and thermal interface.
The 3-phase full bridge kit maps a complete traction inverter topology. It supports applications with multiple modules and is designed for laboratory setups and early vehicle testing. Suitable gate drivers, DC link connections and mechanical interfaces for installation and cooling are integrated.
Both kits facilitate commissioning, system tuning and thermal evaluation, making them practical tools for transferring developments from the laboratory to full-scale production.
Summary
The combination of modular hardware and available development equipment helps to reduce development times, standardize variants and implement new vehicle concepts efficiently. This supports the development of modular architectures for electric drive trains.