UK-based hybrid & electric vehicle powertrain specialist Hyperdrive Innovation Ltd. has developed and built a technical demonstration electric vehicle using its range-extender engine. The range extender is based on a single-cylinder, water-cooled four-stroke engine that builds on proven, low-cost technologies in a design optimized for this application.
|Hyperdrive’s new range extender engine. Click to enlarge.
Based on a standard D-segment family car, the Hyperdrive CUE-V uses the range extender to reduce powertrain weight by 50 kg (110 lbs) while also eliminating range anxiety. The vehicle also demonstrates Hyperdrive’s latest battery pack and battery management system (BMS). In the CUE-V, the 60 kg unit delivers 15 kW at 5,000 rpm—sufficient to allow the vehicle to cruise at 60 mph without depleting the batteries.
This allows a substantial reduction in the size and weight of the battery pack and of associated systems such as cooling and power electronics. Further improvements in power density are expected and the system is designed to allow an efficient design path to future generations.
The new range extender engine is the result of a detailed review of the many technologies available for this application; its development was supported by supported by the Newcastle University Centre for Advanced Electrical Drives.
We started with an open mind and considered many quite radical ideas—including two-strokes, rotaries and gas turbine—as well as more traditional solutions. Each one was evaluated against a pragmatic list of requirements that include cost, refinement, weight, emissions and risk. It became clear that the most attractive solution for the coming generation of range-extender EVs is to build on established expertise.
The cleverness is in the combination of proven and bespoke components that allow the system to exceed the design targets with minimal cost and risk. This approach, combined with our proprietary electronic control system, allows us to fully exploit the potential of near constant-speed operation to deliver greatly improved power density without the cost and risk of significant new technologies.—Hyperdrive director Chris Baylis
The rationale for range-extension. Hyperdrive managing director Stephen Irish suggests that most electric vehicles are fitted with too many batteries, simply to reduce the driver’s range anxiety.
Research has shown that 80 percent of journeys in Europe are less than 30km. Our experience of city trials in the UK shows average journeys as low as 20km. If batteries could be sized for the majority of journeys, the cost and weight of electric vehicles would fall sharply. Batteries also have other issues, such as the environmental impact of mining some of their constituent materials, the challenges of end-of-life recycling and the cooling and control systems that add packaging volume and weight.—Hyperdrive managing director Stephen Irish
Liquid fuels have an energy density around 100 times that of today’s automotive traction batteries. Even the most optimistic projections suggest that this ratio will not improve much beyond 30 times within the next five years, notes Irish.
That means that the most convenient way of travelling long distances remains an internal combustion engine, while the most environmentally responsible way of travelling average distances is using low-emission, night-time generated electricity. With a range extender electric vehicle, you can do both.—Stephen Irish