In order to achieve a zero-emissions future, the automotive industry must reinvent itself. Automakers must bring to
the
market new differentiated electric models fast. NXP and Wolfspeed collaborated to deliver a fully tested 800 V
Traction Inverter Reference Design that mitigates many of the hurdles facing an EV system architect.
Anatomy of the power inverter module.
To support their automotive partners and facilitate the race to vehicle electrification, NXP and Wolfspeed joined
delivering a fully tested 800 V Traction Inverter
Reference Design that mitigates many of the hurdles
facing an
EV system architect, including component selection to increase the system efficiency, meeting functional safety
certification standards and ensuring life-long reliability.
The EV Traction Inverter Reference Design is a full-system solution containing Arm® Cortex®-M7 based S32K39 MCU with
functional safety-compliant power management FS26 system basis chip and the latest generation of high
voltage-isolated
gate drivers GD3162. To complete the
system, the 1200 V six-pack YM SiC power modules from
Wolfspeed have been
associated.
This EV traction inverter reference design has been tested jointly with hardware in the loop (HIL) setup at Wolfspeed
Munich Laboratory. Under an 800-volt battery condition, a performance of over 300 kilowatts at peak power has been
reached.
Test results of HIL setup in laboratory.
Design for Maximum Efficiency: Dynamic Gate Strength Adapting to Varying Power Demands
Laboratory simulation has demonstrated a ~1 % efficiency gain due in part to NXP’s High-Voltage Gate Driver’s
dedicated
feature. This feature provides designers the ability to dynamically adjust the strength of the gate drive signal
based
on real-time operating conditions, achieving a balance between efficiency, switching speed and electromagnetic
compatibility
performance. According to some Worldwide Harmonized Light Vehicle Test Procedure (WLTP) models, this could translate
into a 14-mile increase in extended range compared to traditional EV solutions.
Designed With Functional Safety in Mind: Beyond Device Collateral, System Functional Safety Collateral
When it comes to functional safety (FuSA), compliant components prioritize high quality and reliability. The approach
to
safety is reflected in every step from design to manufacturing, to documentation and support. ASIL D components
compliant with the highest risk level, such as NXP’s S32K396 MCU, FS2633 system basis chip and GD3162 high-voltage
gate
driver, are used in the EV Traction Inverter Reference Design. To ease customer integration, some FuSa documentation
is
also proposed including the System Safety Concept which explains safety requirements from assumed safety goals to
the
hardware and software level.
Designed for Reliability and Life-Long Durability
800 V traction inverter requires a silicon carbide solution. Intrinsically SiC material is more reliable and durable
than traditional silicon IGBTs. Wolfspeed saw an opportunity to integrate advanced packaging technology into their
automotive qualified YM package to deliver further enhanced system durability.
The 1200 V six-pack YM SiC power module is designed with a direct-cooled copper
pin fin
baseplate, providing a
straightforward system assembly with enhanced thermal performance with pin fins directly submerged into the coolant.
System operating temperatures are lowered with a Silicon Nitride substrate, a robust ceramic with excellent thermal
shock and wear resistance, as heat is efficiently dissipated from the die. Another innovative packaging feature is
sintered die attach, a state-of-the-art die attach technique creating a robust bond between the die and silicon
nitride
substrate, once again ensuring excellent heat conductivity and mechanical durability to enable higher power and
superior
thermal cycling performance. Both direct-cooled copper pin fin and sintered die attach technology improve thermal
performance and system lifetime.
YM modules replaced traditional wire bonds with a copper top side clip to improve module ampacity, power cycling
lifetime, and enable an optimized terminal layout, minimizing package inductance to reduce voltage overshoot and
achieve
ultra-low switching loss. To reduce potential mechanical failures, the automotive grade YM module is equipped with
hard
epoxy encapsulation – Epoxy mold compounds are replacing gel-based encapsulants, providing superior moisture
resistance
and structural integrity. The combination of sintered die attach with copper clip and epoxy mold compound enables up
to
3× increase in lifetime compared to the closest competitor.
Wolfspeed’s six-pack YM SiC power modules.
These advanced packaging technologies help the AQG324 qualified YM3 power module alleviate concerns operating in a
harsh
automotive environment – enabling consistent performance with unmatched durability.
Our Offering
NXP and Wolfspeed’s 800 V Traction Inverter Reference Design marks
a pivotal advancement in the automotive industry’s
transition to electric vehicles. This reference design addresses key challenges facing EV designers including
improving
efficiency, functional safety and long-term reliability, ensuring that electric vehicles can match or exceed the
performance of internal combustion vehicles. With features like dynamic gate strength adjustment and advanced
silicon
carbide power modules, the reference design is an essential tool to designers committed to delivering high-quality,
efficient and safe electric vehicles, ensuring performance across the lifetime.
