Hybrid Cars Open Doors for Electronic Component Makers

Toyota Motor Corp of Japan released its new sports utility vehicles (SUV), the Harrier Hybrid and Kluger Hybrid, on March 22, 2005, both mounting hybrid systems with high output (see Fig). The combination of the 3.3-liter V6 engine with the hybrid system delivers a high total system output of 200kW, with acceleration characteristics on a par with V8 engines.

Even better, 10-15 mode fuel mileage is 17.8km/l, 0.6km/l higher than the 1.5-liter Corolla.

The growth in the hybrid vehicle market represents a business opportunity for electronics manufacturers. For example, the rear motor in the new hybrid SUV uses key rotors and stators procured from Hitachi Ltd of Japan.

The new designs are also the first hybrid SUVs in the world to use 42V power steering. Most cars today use a 14V power supply, but the increased vehicle weight made it necessary to boost the voltage to 42V to provide the needed output with the smaller motors.

This will open the door to a new 42V electronics market, providing electronics manufacturers with a host of new opportunities.

Higher Output

The new hybrid SUVs have also had the voltage of the NiMH rechargeable batteries boosted to a maximum of 650V, 1.3x the level of Toyota's environment-focused Prius, to achieve higher output. The peak speed of the front motor is 12,400rpm, 1.9x the speed of the Prius, with a peak output of 123kW.

The new hybrid SUVs use a 4-wheel drive system, which means rear motors, too. The rear motors can be driven at the same 650V max as the front motors, with a high 50kW peak output. Toyota adopted a simple 4-wheel drive hybrid system in the Estima Hybrid released in June 2001, but because the voltage of the rechargeable batteries was not stepped up, rear motor output was only 18kW.

The module case for the NiMH rechargeable batteries, holding eight cells, has been switched from plastic to Ni-plated steel to improve heat radiation performance. The cells themselves are about the same as those used in the Prius, except that total rechargeable battery weight has been boosted to 69kg for 240 cells. The Prius was only 39kg for 168 cells, which works out to 13kg more when calculated for 240 cells. An engineer at Toyota commented, "The hybrid SUV outputs high currents from the rechargeable batteries more often than the Prius, for acceleration. Even with the increased weight we had to improve heat radiation performance."

by Koji Kariatsumari

(June 2005 Issue, Nikkei Electronics Asia)