 |
High unsprung weight?
The unsprung weight has increased by less than 2 kg over the original standard Mini. This has been achieved in the first part by removal of the disc, brake caliper, half shafts and cv joints. Secondly we have designed a very light motor and electronics system. As a comparison the power electronics (included inside the wheel) is around 20 times lighter than the lightest currently available alternative! The motor is around 5 times lighter than the closest rival. So we have a 350v 400A continuously rated (0ver 600A peak rating for a few seconds, although this has so far not been used!) system which weighs less than 24kg total.
The fully laden weight of the standard Mini is 1300kg. The vehicle weight after modifications is less than 1500kg. The engine/generator mounted under the boot weighs less than 50kg.
Faster acceleration?
The original Mini with 4 passengers and some luggage is specified as 1300kg. The modified Mini QED weighs in at 1500kg with the same payload. We have been concerned with the mechanical ruggedness of original suspension arms etc. It is true we should be able to achieve faster times. We may push the limits when we have a good number of miles of testing under our belt!
Total energy transfer in less than a second?
It is sometimes a little misleading to consider power. Better to consider torque. As gravity, vehicle mass and tyre to road friction coefficient dictate the maximum torque transfer, it is this that dictates the maximum acceleration rate. So we obviously cannot get the full energy into the vehicle in less than a second. We could have some serious fun (and smoke) trying if the anti skid was disabled!!
Heavy batteries?
The batteries and super capacitors weigh in the same as the engine and gearbox which was removed. The location of this mass is also precisely the same as the original car, so handling is unaffected. The batteries and super caps weigh around 190kg.
Power at what speed?
The motors develop 750Nm each. This torque is relatively flat and drops off to around 600Nm at top speed! So the power is only 120kw at top speed. However, it is the torque which matters since power at lower speeds is low, but for good acceleration (and braking!) torque is what is important.
The Super capacitors are sized to hold the full energy of the vehicle kinetic energy at 70mph. This is around 700kj. So as the vehicle speed increases we maintain "space" in the capacitors to absorb the regenerated energy from braking to stop from this speed. Note that the regenerative braking captures about 85% of the available kinetic energy from the vehicle motion. This means that you no longer need feel guilty about the amount of fuel burned when accelerating fast from the traffic lights! Most of the energy used to perform this acceleration will be recovered when you stop!
Safety concerns?
The braking system is fully dual circuit and each wheel is independently connected to the brake system. Each wheel has several levels of redundancy so any single failure will never prevent the vehicle from operating safely.
Someone said, "Ah but there is only one battery and if this fails or if a main fuse blows the vehicle cannot stop!” In fact when the vehicle is moving, the battery is no longer needed for braking power since the wheels themselves generate all the power needed to stop. This is the basis of regenerative braking and PML system can regenerate down to stop.
|
|
Tel: +44 (0) 1420 594140, Fax: +44 (0) 1420 83930, enq07@pmlflightlink.com
Deutsch
Hi-Pa Drive™
