Full power at all times - Siemens VDO develops energy managers for the automobile

In the early automobile development, six volt batteries were sufficient to ensure the engine ignition. Today, this limited stored energy resource would not meet the demands made on the modern automobile electric power supply network. Electric power requirement has nearly quadrupled over the past 30 years. In fact, simply starting a vehicle can demand as much as eight kilowatts of electric power.

To meet the modern vehicle's increasing energy requirements, Siemens VDO Automotive has developed the "Power Trader" software, which enables the automobile's electrical systems to mutually regulate power requirements in line with available supply and instant demand. The innovative software shifts power usage throughout the vehicle, from comfort and convenience features that consume large amounts of energy to safety and driving-relevant systems when even more electricity is needed. For example, the power requirements of a turbocharger and other electronic drivetrain components in passing or overtaking operating conditions can be met by decreasing the electrical consumption of the seat heating element for a few milliseconds. The Power Trader software solution can be implemented without having to make major modifications to the vehicle's electrical system or install additional controllers.

Siemens VDO Automotive estimates that by 2005, an average vehicle's power demand will rise to approximately 2.5 kilowatts. Consumers expect seats to heat up quickly, air conditioning to be cool and refreshing when parked and the stereo system to provide quality entertainment at all times. In addition to the growing number of standard comfort and convenience features, the onboard network also has to power fuel systems, power steering, airbag sensors and electronic stability control. A particularly high power supply is required during starting, enabling even the largest engines to be brought to life in all weather conditions.

While Power Trader is an immediate solution to vehicle electrical energy resource management, Siemens VDO Automotive's integrated starter-generator (ISG) is a mid-term solution to providing the necessary electricity to power new automotive engineering developments. The ISG provides more than six kilowatts of continuous electrical energy and increases the onboard network to 42 volts.

In addition to power supply improvement and augmentation, the ISG can boost internal combustion engine output during the acceleration phase or completely power the vehicle in stop-and-start situations. Siemens VDO Automotive plans to utilize high-performance capacitors, or supercaps, that can be highly charged with electrical energy during normal vehicle operation (such as when braking) to enable these advanced functions. Integrated starter-generators are expected to be introduced in conjunction with the 42-volt onboard network in 2010.

In the longer term, electrical power demand will be dictated by the automobile's powertrain, with the supply of other onboard network energy consumers playing a subordinate role. By approximately 2020, fuel cells will very likely be employed as primary vehicle drives or as a complement to the internal combustion engine as ancillary electric power packs. However, fuel cells attain their maximum power output after few minutes of operation, requiring energy management and high-capacity energy accumulators to continue to be needed in the future.

The performance levels of future automobiles will continue to increase and Siemens VDO Automotive will be providing innovative energy management solutions to ensure they have the necessary electrical power needed to meet ever-evolving consumer demands.