Internal combustion engine used to ‘hybridise’ EVs and remove range anxiety
Electric vehicles (EVs) are increasingly being used, but at the moment they remain restrictd to niche applications on inner city roads. In part, this is because EVs have two main barriers to entry: cost and range. As far as cost is concerned, it is hoped that, with higher volumes, purchase cost will come down. This in turn will help to introduce EVs in to the second hand market, which will be when they really start to hit the mainstream.
However, none of this can happen if EVs do not address the fundamental problem of range. Admittedly, research shows that most roundtrips cover under 100 miles, which is just about within the range of most of today's EVs. However, some journeys are longer. And most people will not pay more to get less. People want more and that means a range in the region of most internal combustion engine cars.
Northumberland-based Hyperdrive has come up with an interesting take on the problem, flipping the notion of a hybrid on its head. It has introduced a small internal combustion petrol engine that plugs in to the battery system of an existing electric vehicle. Known as the Range Extender, the system is designed to turn on during longer journeys, to charge the batteries. However, for the shorter journeys that make up 99% of most trips, the vehicle will be driven by its electric system. It has already been installed on a demonstration electric vehicle, the Avid CUE-V, with promising initial results.
"We started with an open mind and considered many quite radical ideas," says Chris Baylis, managing director of Hyperdrive. "These included two-strokes, rotaries and gas turbines as well as more traditional solutions. Each one was evaluated against a pragmatic list of requirements that included cost, refinement, weight, emissions and risk."
There is no link between the engine and the electric motors that drives the wheels. The engine is purely there to act as a generator for the battery system. The fuel tank is also significantly smaller than normal cars as well, likely to be around 15-20 litres on a D-segment family car. The result, it is hoped, will be a car that should have a range of about 300 miles and an equivalent g/km of CO2 of between 73 and 99.
"The engine has been carefully selected for this application," says Baylis. "What we are trying to do is to bring proven bits of technology together and do all the clever stuff with the electrical control and electronics so we can get the device to market ASAP. Our proprietary electronic control system allows us to fully exploit the potential of near constant-speed operation to deliver greatly improved power density."
Hyperdrive's Range Extender is based on a single-cylinder, water-cooled four-stroke engine that has been selected for its low cost and optimisation for the unique usage pattern of this application. The 60kg unit delivers 15kW at 5,000rpm, sufficient to allow the vehicle to cruise at 60mph without depleting the batteries.
Baylis believes this system offers the highest energy density of any comparable system on the market today and further development will allow for a substantial reduction in the size and weight of the battery pack and of associated systems such as cooling and power electronics. The cable-free design integrates LiMnCo Pouch Cells with Hyperdrive's Battery Management System in a scalable, modular design that can also be supplied for other chemistries.
"If you commuted to central London, you could drive in with Range Extender and then switch to total EV mode for the Emissions Zone and Congestion Charge," says Baylis, "so there are different ways you can use it. It can scale up and down, so has potential to be used on all sizes and types of vehicles."
