Battery-powered vehicles have been with us for many years, as golf carts, for example, and in many other niche or specialist applications.
Lately the impact of two major drivers has focused greater attention on the acceptability and benefits of electric vehicles -- the skyrocketing price of hydrocarbons and air pollution.
Leading-edge UK manufacturer Zytek saw the need for electric vehicles in 1994 when co-founder Bill Gibson, a long-time proponent of lightweight, very high performance electric vehicles, began developing what would become the highest power/density ratio, electric vehicle drivetrain to date.
Gibson realized that two of the major challenges -- precision engineering and control systems -- were areas where Zytek had exceptional expertise, gained from work with Chrysler on hybrid street vehicles and from Zytek’s own F1 racing engine management experience.
Initial development and test work centred on a Lotus Elise, followed by the ultra compact smart car chassis, the EV10-15. Following successful completion of this project, brand owner Mercedes-Benz commissioned Zytek to convert 100 "smart fortwo" cars to electric propulsion at their production facilities in Fradley, Staffordshire. The vehicles are being delivered in a market trial to selected British customers as lease vehicles.
The drivetrain installed in the smart electric vehicle uses state-of-the art brushless dc motor technology, designed and manufactured in-house by Zytek. This innovative drivetrain integrates the electric motor, power and control electronics into one compact assembly with only three connections: water, high voltage (300 V), and low voltage (12 V).
Finding the Right Tester
With each motor assembled by Zytek prior to fitting, a test instrument was needed to run a number of tests on the wound stator prior to shrinking it into its aluminum case and fitting a brushless rotor, and then again after the motor was potted and assembled prior to fitting into the vehicle. A subsequent high-volt test on the whole electronics loom completed the sequence.
Using accumulated data from the tests, feedback was initiated between Zytek and the UK motor windings manufacturer, resulting in a virtually nil rejection rate as the build continued.
A visit by Zytek engineering staff to the Berlin Coil Winding Show led to selection of Whitelegg Machines Baker AWA-4 tester for this purpose. The AWA was chosen because it had the versatility to test short production runs, was easily portable, and had the flexibility and capacity to run resistance, Hi Pot, Meg Ohm, peak-to-peak tests, and more. The software delivered reports in MS™ Access, easily downloadable on a Windows platform.
“Other testers were designed for long production runs,” said Neil Heslington, managing director, commenting on the utility of the AWA. “The AWA is a flexible instrument equally at home in the factory’s various test situations as well as on our much shorter batch runs. The software is particularly straightforward and good for PC interpretation.”