The 640 bhp MINI QED plug-in EV
September 4, 2006 Q.E.D. is an abbreviation of the Latin phrase "quod erat demonstrandum" which means, "which was to be demonstrated". In simple terms, it indicates that something has been definitively proven. Accordingly, the MINI QED electric hybrid is aptly named as it dispels any doubts about the validity of in-hub electric motors playing their part in the future of the automobile. PML FlightLink designs and manufacture electric motors, EV drive systems, joystick controls and controllers and bespoke motors for specialist applications and the MINI QED was built to showcase their expertise in wheelmotors, with a view to supplying what we expect will be a booming market in electric vehicle applications over coming decades.
The result is a MINI with four times the horsepower of a Cooper S, supercar performance and the prospects of some very serious EVs in the near future. The QED is a ripper, using four 120kW (160bhp) wheel motors complete with invertors to convert momentum back into stored energy under brakes. With one on each corner you have Ferrari-like power and very controllable independent drive on all four wheels.
In the MINI QED, this package offers a 0-60mph time of 3.7 seconds and a 150mph top speed – supercar territory. An on-board petrol engined generator offers enough electrons to run continuously at motorway speeds without depleting the battery, and you can plug it in at night and commute in full electric mode if you wish.
As the invertor can exert more retardation than brakes, the conventional disc brakes have been discarded altogether.
The inwheel motors and magnesium alloy wheels, and tyres, have a total mass of 24kg. The original assembly mass on the MINI One was 22.5kg. With so little difference in unsprung mass (the brake hubs and discs have been removed), and full regenerative braking, the ride is claimed to be no different.
More importantly, it means dynamic management of up to 750Nm torque at each wheel, (3000Nm total) in either direction, to ensure optimum use of available power. The system can also use steering (driver intent and wheel alignment) and vehicle attitude (gyroscopic sensors read pitch, roll and yaw) as inputs to the traction control and vehicle stability systems. Put simply, the vehicle stability system will be the key, and it will ultimately be the software that determines what the optimum tractive distribution will be at each instant - how the energy stored in the 300V 70Amp Hour (700Amp peak) Lithium Polymer battery is most effectively distributed.
The management system dynamically monitors each wheel to detect skid onset and manages this state to obtain maximum non-skid torque from wheel in both acceleration or braking modes – this is ABS and traction control and more because the power distribution can be altered every thousandth of a second – infinitely more control than we currently have with conventional petrol engines and power trains
Another of the tricks employed by PML is the use of a 350V, 11 Farad ultracapacitor. Capacitors are used to store electrical energy and can release/absorb their energy 10 times faster than a battery. Using an ultracapacitor means that acceleration or power boost at higher speeds can get energy twice as fast at peak draw, offering “nitro-like performance.”
Similarly, so that the car can drive a significant distance, PML has used a very small, lightweight 250cc four stroke motor to power a highly-efficient electrical generator. The engine is run at a continuous speed and load, which results in optimum efficiency fuel conversion. After delivering the energy to the battery system the mileage translates to around 80mpg and gives the QED a range of 1000 miles (1500 kilometres) between recharges or visits to the petrol station. Driving it without the generator offers a still healthy (by EV standards) range of 200-250 miles (350 to 420 km depending on how much of a leadfoot the driver is).
Three driving modes are available to the QED driver via the touch-screen in-car display. Imagine starting your journey in the city in Eco mode then selecting normal mode as you reach the suburbs, and finally Sport mode as you hit the open road. The all-electric Eco mode sees the four-stroke generator engine dormant unless directed by the operator. In normal mode, the generator starts when the battery drops below 50% charge and sport mode offers enhanced performance.
The MINI was chosen as the platform for the QED because of its broad appeal and iconic styling. Also, despite its diminutive stance, it is not a light vehicle and has limited space to integrate the substantial component set required for a top performance electric vehicle – in successfully converting this vehicle then most others should be easy by comparison!
It’s a shame they didn’t pick a lightweight automobile because the same 4 x 160 bhp motors in cars much lighter than the MINI would produce perhaps record setting performance. The availability of PML Flightlink’s high efficiency brushless permanent magnet sine wave Hi-Pa drive 24 phase water-cooled motors in the near future on a commercial scale could ignite a new industry in electric vehicles.
The vehicle development will continue for some time, especially in the area of engine/fuel options and GPRS services and features. Some of the features envisaged via the GPRS ink include:
- Journey / energy reserve matching
Prediction of journey radius available
Automatic speed limit control (optional!)
Driving license optimised speed constraints
Remote diagnosis of any system fault conditions
Auto reporting of breakdowns
Auto location for attending engineer