Starter Current Module, DC/DC converter stabilize power in Mild Hybrids

July 10, 2013 // By Christoph Hammerschmidt
The operation of start-stop systems in vehicles poses challenging conditions to the electronics installed in that vehicle: It generates high transient voltages and currents that cannot be covered by the normal battery. Automotive electronics supplier Eberspaecher Controls therefore has developed a SCC (starter Current Control) Module that protects the starter battery during engine restart.

The SCC is based on power semiconductor technology and limits current variations occurring during the engine start procedure. It can be attached directly to the battery terminal and prevents under-voltage in the car's internal power grid, and ECU resets that might occur as a consequence of such under voltage conditions. Thanks to its concept it is reusable, doing away with the one-time usable pyrofuse that in the case of a crash separates the battery from the vehicle's electrical system.

For plug-in hybrids with a multi-voltage power supply (12V and 48V) and thus with multiple energy storage systems, Eberspaecher also has developed a DC/DC converter. The 3kW device supplies 48V high-power loads such as electrical turbos, power brakes or power steering systems. It reduces the current across the power lines while maintaining the power level, effectively offloading the 12V system and stabilizing the voltage at both levels. The batteries used to buffer the recuperation energy are spared.

Fig. 1: Eberspaecher's 3kW DC/DC converter connects the 12V and 48V levels in hybrid vehicles.

This is particularly relevant for the operation of start-stop and coasting systems: When the engine is off in start-stop operation, generator and vacuum pumps are deactivated too. The vacuum required for the operation of the brake then is created by the electric power brake which gets its energy from the 48V level through the DC/DC converter.

Eberspaecher will display these systems at the upcoming IAA International Motor Show in Frankfurt (September 12 to 22).