Tevva Motors develops electric range extender for trucks

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A new electric range extender powertrain, which can be retrofitted to any 7.5-metric ton truck, is currently being put through its paces on roads across the UK

Development of a new environmentally friendly, low-emission solution for back-to-base fleets is well underway. Currently being tested on UK roads with three vehicles – one of which is in daily use with logistics operator UPS – the electric range extended drivetrain has the ability to reduce and avoid producing emissions completely thanks to Tevva’s intelligent predictive software. It can be fitted into an existing 7.5-metric ton truck, either as a retrofit package or on the production line during the build process.

Richard Lidstone-Scott, business project manager, Tevva, says, “We have completed the proof of concept and we are now in the process of re-designing the system so we can manufacture it in large volume and at a cost effective price.”

The drivetrain consists of a single 120kW electric motor, capable of producing 1800Nm from zero rpm, powered by 66kWh batteries located on the chassis. The drivetrain also has a range extender unit, which uses a small capacity diesel engine to generate additional charge while on the move.

It is controlled by Tevva’s patented Predictive Range Extender Management System, which enables the best, most efficient use of electric range extended drivetrain without input from the driver. With real-time access to NOx, air quality data and GPS navigation, the vehicle knows when to use the range extender and when to avoid use.

Development for the system began in October 2014 when initial designs took shape. An extensive amount of modeling was required to establish how much energy a typical vehicle needs for a set amount of mileage, how much range extender would be needed, and how to use that in the right place.

Not only did Tevva have to model the amount of power needed to drive a truck, to ensure it performed as well as a normal diesel, Tevva also had to model the amount of energy needed in a worst case scenario – to drive the truck with a flat battery. This gave the starting point for specifying the traction motor, internal combustion engine and generator.

Tevva then developed proprietary algorithms that model the energy usage of the truck on a defined route, which calculates the optimum time to run the Range Extender, if necessary.

“We also put the range extender diesel engine on the dyno at Revolve Technologies in Essex, UK – which we are working with in building the components – to map out where the most efficient points to run this engine are,”says Lidstone-Scott.

“A normal Diesel engine has a power and torque curve and an engine is usually operated across the full range. We had to find out the best points to operate the engine to generate maximum efficiency for the engine and max power. This meant running unit at multiple set points to define the ideal operating points for our needs.

“This investigation gave us three operating points; one for low noise, for use at standstill and low speed, one for high efficiency, for minimum fuel used versus power output, and a final point for high power, when you have a fully laden vehicle with a flat battery and need to drive a long distance.

Real road testing was conducted at Millbrook Proving Ground in Bedford, in the UK with a focus on speed, braking, load carrying and incline performance. In one particular test for example, the vehicle was driven up the 26° hill incline at Millbrook fully laden. Vehicles have also been driven on public roads across the UK and to Rotterdam in the Netherlands.

“During the design phase, we thought it would be difficult to get everything packaged and put into place. But looking back, that wasn’t the difficult bit – the challenge was actually integrating the different technologies into one solution, ensuring that all the components interact together,” Lidstone-Scott explains.

“Also, ensuring interaction between charging the battery with the range extender and balancing the power going to the battery pack from the regenerative braking – testing and validating that from a safety point of view has been incredibly time consuming.”

This week (commencing February 3), one truck is being driven to Leyland in Lancashire. A suite of production tests are also planned once the next set of designs are finalized. Vehicles equipped with the technology should be in full scale production within the next three years.

February 3, 2016

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John joined UKi Media & Events in 2012 and has worked across a range of B2B titles within the company's automotive, marine and entertainment divisions. Currently editor of Automotive Testing Technology International, Crash Test Technology International and Electric & Hybrid Marine Technology International, John co-ordinates the day-the-day operations of each magazine, from commissioning and writing to editing and signing-off, as well managing web content. Aside from the magazines, John also serves as co-chairman of the annual Electric & Hybrid Marine Awards and can be found sniffing out stories throughout the halls of several of UKI's industry-leading expo events.

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