This Vivaro through-the-road hybrid vehicle demonstrates a practical, cost-effective and efficient way to retrofit a commercial vehicle into a plug-in parallel hybrid by simply adding two in-wheel motors and a battery. Our technology is uniquely designed for high-output, high-efficiency operations. Our in-wheel motors are unique in that they have the rotor on the outside and each motor’s electronics on the inside. That simplicity of design creates more power density per motor and much simpler vehicle integration. It’s the closest thing to a bolt-on hybrid system.

—Protean Chairman and CEO Bob Purcell

Protean Electric outfitted the front-wheel-drive Vivaro with a through-the-road hybrid conversion kit of two Protean Electric PD-18 motors attached to the rear axle. The two motors together provide torque assist of up to 1,180 lb-ft (1,650 N·m) peak and 740 lb-ft (1,000 N·m) continuous at the rear wheels.

Each motor has a built-in inverter, control electronics and software. Protean’s in-wheel motors are based on a modular redundant architecture, in which individual autonomous submotors are controlled by associated micro-inverters and work cooperatively to deliver the total power and torque or the motor as a whole.

In addition, Protean added a 21 kWh battery pack, giving the vehicle more than 55 miles (90 km) of electric propulsion range and plug-in hybrid and electric vehicle capabilities. While operating in hybrid mode, the Vivaro measured 114 mpg (2.4 liters/100 km) operating over the NEDC, more than three times the fuel economy of the conventional vehicle, Protean said.

The system can also deliver regenerative braking on the rear wheels with no

modifications needed to the existing front brakes while retaining the vehicle’s original engine and drive system. This high level of regenerative braking allows manufacturers to use a smaller battery size or extend the range with the same battery size.

The Vivaro retrofit also allows the driver the advantage of being able to switch between multiple operating modes: two- or four-wheel drive operation, IC engine-only drive, electric-only drive, or an electric torque assist Through-The-Road-Hybrid.

The vehicle underwent a testing regime jointly conducted by Millbrook and Protean Electric. Work is now underway to build a Vivaro Plug-In Parallel Through-The-Road-Hybrid test fleet for select fleet customers.

Fleet operators should be lining up for a vehicle such as this that will provide more than a 65 percent reduction in fuel usage and CO₂ emissions in a typical urban drive-cycle, while enabling electric-only operation for in-city low-emission zones such as London.

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Bob Purcell