Inverter designs gain traction

ON Semiconductor has launched a family of power modules and two reference designs aimed at high-voltage automotive traction inverters (writes Nick Flaherty).

The first two VE-Trac modules are intended for main traction inverters of all types of electrically powered vehicles including battery-electric vehicles, plugin hybrids and full hybrids.

There are two inverter design platforms for the modules, the VE Trac Dual and the VE-Trac Direct. The VE-Trac Dual uses dual-sided cooling (DSC) half-bridge modules that are stackable and scalable for traction designs from 80-300 kW with minimum mechanical redesign. Both can operate continuously at junction temperatures of up to 175 C.

Double-sided cooling boosts the performance of a new module for traction inverters

The first device for the VE-Trac Dual reference design device is the NVG800A75L4DSC. It is rated to 750 V at 800 A, or twice the capacity of current modules. This is achieved through the double-sided cooling of the IGBT silicon switches in the module, giving it the dual name.

The NVG800A75L4DSC is qualified to the AQG-324 European Qualification Guideline for Power Modules for Use in Power Electronics Converter Units in Motor Vehicles for silicon-based modules.

It uses an embedded IGBT with additional processing that provides a faster reaction time for the integrated overcurrent and over-temperature protection. Avoiding the use of wire bonds in the module doubles its rated lifetime.

By contrast, the VE-Trac Direct uses single-sided cooling. The first module for this is the AQG-324-qualified 750 V, 820 A NVH820S75L4SPB. It uses the more conventional six-pack configuration that is widely adopted by automotive OEMs and Tier 1 systems providers, and so allows multi-sourcing to be achieved with minimal layout changes.

Six Field Stop 4 750 V Narrow Mesa IGBTs in the module have lower power losses during lighter loads, which helps to improve overall system efficiency in automotive applications. The module also uses an improved design of pressfit pins on the signal terminals to make it easier to assemble an inverter.

Future devices in the VE-Trac family will include discrete power devices, isolated gate drivers and a wider range of current and voltages for modules, as well as wide-bandgap silicon carbide for higher temperature operation and higher performance