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Zytek develops revolutionary diesel hybrid with MCC smart - October 2001 |
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Zytek Electric Vehicles, in partnership with MCC smart and DaimlerChrysler AG, has developed a unique diesel hybrid powertrain for the smart City-Coup. The vehicle, first exhibited at IAA in Frankfurt in September, uses a custom-designed electric motor to accelerate it quickly to almost 60km/h.
At greater speeds the diesel engine cuts in to take the car to 100km/h in just 17.8 seconds, two seconds faster than the standard diesel configuration. Comparative tests on both the diesel hybrid and the standard diesel revealed an improvement in fuel consumption of more than 13%, with the hybrid consuming less than three litres per 100 kilometres.
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The Zytek electric motor used in the revolutionary smart hyper (hybrid and performance) has been designed to fit neatly into the space between the engine, the exhaust and the driveshaft and weighs only 19kg yet produces a power of 25kW and a torque of 55Nm from 0 to 4000rpm. The permanent magnet, dc brushless motor, developed by Zytek, helps reduce CO2 emissions to less than 80 grammes per kilometre. “We have been very impressed by the performance of the hybrid powertrain produced by Zytek,” comments Dr. Tilo Schweers, manager, special vehicle engineering at MCC smart. “It is lightweight and very compact, allowing it to be installed in the vehicle without the need for major modifications. The Zytek, DaimlerChrysler and MCC partnership has allowed us to develop this concept which we hope to take further in the future.”
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The decision over which power source to use is made automatically by a central electronic control unit which selects the optimum source for the best system performance. The controller, designed by Zytek, incorporates an Infineon C167CR processor and uses a dual CAN communications protocol. The unit also allows the electric motor to provide ‘fill-in torque’ to facilitate smooth gear changes by providing propulsion for a few tenths of a second in between gearshifts. “The fill-in torque evens out any lag between gears to make gear changes almost imperceptible to the occupants,” says Jon Horsley, the Zytek project manager responsible for the diesel hyper smart.
To further improve efficiency, the controller allows energy to be recovered on braking and deceleration by using the motor as a generator to recharge the batteries. The electronic controller regulates the regenerative charging based on the battery charge level. This recuperative braking allows a further fuel saving of around five to six percent.
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Zytek has worked closely with DaimlerChrysler AG Research and Advanced Engineering to develop the powertrain for the vehicle, which has already undergone successful initial testing. At this stage the drive presented serves to demonstrate the technology; a decision about series production has not yet been made. “We are confident that the combination of diesel engine with the unique Zytek electric motor and electronic control unit will be a real competitive advantage to MCC smart in the future as emissions levels and corresponding fuel consumption targets continue to decrease, “concludes Horsley.
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GM introduced its Light Hybrid System in 2004 on the Chevrolet Silverado and GMC Sierra extended cab pickup trucks. These trucks deliver 10 percent improved fuel economy over the conventional models and the highest city fuel economy of any V6 or V8 full-size truck.
The conventional starter motor and alternator is replaced by a Continental ISAD electric motor integrated between the engine and transmission, known as a flywheel alternator starter system. The electric motor provides fast, quiet starting power, and the ability to generate up to 14,000 watts of continuous electric power. This mild hybrid application increases fuel economy, mainly due to the engine start/stop function and regenerative braking that turns the motor into a generator as the truck decelerates. For additional fuel savings, the flow of fuel is shut off instantly any time the truck is coasting or braking, even during a transmission gear change. These features operate completely seamlessly, giving the driver extra functionality whilst saving fuel, a win-win situation. |
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The electricity generated by the system also has many uses. It may be stored temporarily in a 42-volt lead-acid battery pack and used later to enable engine auto starts and other hybrid functions.
It can also be used to support on-board electric accessories. It even can provide unique accessory power through four 120-volt AC mains outlets, two in the cab and two in the pickup bed, to operate power tools at a construction site or to run essential home appliances during power outages.
These outlets can even operate with the ignition key removed and the truck locked, turning the vehicle into a mobile yet secure generator.
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Zytek were responsible for all the hybrid engineering undertaken on the program with up to 50 engineers working on the program from 2000-2004. A small team continues to support the year on year legislative developments, necessary to keep the vehicle in production.
Zytek’s responsibilities for the program were:
- Initial architecture study defining the optimum hybridisation solution– Hardware, Software and Calibration
- Powertrain Control module –Engine and transmission control software modification
- Battery control -SOC, SOH, energy management
- Diagnostics and safety analysis
- Transmission. Engine and Hybrid Control Module calibration
- Driveability calibration to GM worldwide standards
- Full environmental certification. Durability, validation and sign off
- Total program management, $30M program delivered on time and to budget
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