42 Volts Here Before You Know It COLUMN BY RANDY RUNDLE A recent Ford Motor Company press release pro- vides a timeline of things to come. “In 2003, Ford will introduce the world’s first hybrid electric sport utility vehicle, based on the Ford Escape. That will be followed a few years later by an Explorer that will achieve breakthrough levels of fuel economy and offer more high-tech comfort and convenience features. “Tt will use a new higher voltage electrical system that enables several fuel saving functions, including the ability to shut off the engine when the vehicle is stopped and to start it instantly on demand. This start-stop engine tech- nology is known in the industry as an integrated starter-generator, or ISG. “The integrated starter-generator, as its name implies, replaces both the conventional starter and alternator in a single electric device. A vehicle equipped with the ISG system could be consid- ered a mild hybrid because it is capable of most of the functions of a hybrid electric vehicle. “There are three functions common to both a full hybrid electric vehicle and ISG, or mild hybrid, and a fourth func- tion unique only to a full HEV: Start/Stop. When the engine is not needed, such as at a stoplight, it auto- matically turns off. It restarts smoothly and instantly when any demand for power is detected. This “stop/start” function provides fuel savings and reduced emissions. “Regenerative Braking: This feature collects energy created from braking and uses it to recharge the vehicle’s batteries. This allows items such as the headlights, stereo, and climate control system to con- tinue to operate when the engine shuts off. By greatly reducing the amount of electric power that must be generated by the engine, regenerative braking signifi- cantly reduces fuel consumption. “Electrical Assist: Internal combus- tion engines on both types of systems receive assistance from an electric motor, but in vastly different ways. The electrical assist ISG system helps the engine at startup and during hard accel- eration, providing short bursts of added power. Because the ISG system uses a 42-volt battery and the hybrid electric vehicle uses a 300-volt battery with a much larger energy capacity, the HEV electrical assist is capable of providing much more power, more frequently and for a longer duration. “Electric Drive: Only full hybrids have the ability to drive in electric-only mode. In the Escape HEV, this means the SUV’s electric motor can drive the vehicle at low speeds, under 30 mph (km), while the engine is off. The capac- ity for electric-only drive clearly sepa- rates a full hybrid electric vehicle from a mild hybrid vehicle using an ISG sys- tem. This start-stop feature debuted in Ford Motor Company’s P2000 HEV concept car, which was delivered to the Department of Energy in October 1999. How it Works “Tn addition to the 42-volt battery and integrated starter generator, the system is comprised of three major components: a slightly modified V-6 engine, new auto- matic transmission, and an invertor/ motor controller. When restarting, DC power from the battery is processed by the invertor/motor controller and supplied as adjustable frequency AC power to the ISG. The frequency of the AC power is controlled to bring the engine up to idle speed in a small fraction of a second. “Regenerative braking captures energy normally lost as heat energy during brak- ing. The ISG absorbs power during vehi- cle deceleration, converts it to DC power, and recharges the battery. Electro- hydraulic brakes replace the vacuum booster, and microprocessors control the operation of front and rear brakes to maintain vehicle stability while braking. The vehicle’s mechanical brakes are coordinated with the ISG, so the differ- ence between mechanical and regenera- tive brakes is transparent to the driver. “The ISG also provides added power and performance. The ISG delivers bat- tery power to the wheels to assist the engine during vehicle launch. The 42- volt battery system coupled with the ISG system on the Explorer will be a more powerful electrical system that delivers 42 volts rather than today’s existing 12-volt system. A smaller 12- volt battery, roughly the size of a motor- cycle battery, will be used to operate standby items such as emergency flash- ers and the radio. “Every year, automobiles require more electrical power for new vehicle features. Items such as electronically heated seats, entertainment and naviga- tion systems are already reaching the upper capacity limits of current 12-volt systems. The 42-volt systems provide the extra power needed and also reduce the size of the electrical wiring, making a car lighter and more fuel-efficient. “About one mile of wiring will go into the electronic intensive car of the near future. With a 42-volt system, wiring bulk is reduced because higher voltage lowers the electrical current, enabling narrower gauge wiring. The 42-volt electrical system allows the company to more quickl