Perhaps you have other figures about MBHPE Ltd. system. I have 25 kg total weight for the whole KERS system including battery (14.7 kg) which provides 60 kW for a boost time of 6.7 s. source for KERS figuresriff_raff wrote:9Kg for a 60KW PM electric motor would not be possible if the motor is designed to turn at wheel speeds. To get a 60KW output from a 9Kg PM motor, the motor would need to be rated at very high RPM's, thus necessitating the use of a speed reduction gearbox. The best you could hope for with a wheel speed samarium-cobalt or neodymium-iron PM motor is about 4 KW/Kg, or about 15 Kg per motor. And they would also need to be liquid cooled at the charge/discharge rates needed for your F1 KERS.
If you take away the weight of the battery and allow for a water cooled inverter you cannot fail to arrive at a weight very close to 9 kg for the motor. Of course it will be water cooled as all very high power asynchronous servo motors are. I have previously pointed out that those motors can be 100% overloaded in a peak application that involves less than 20 seconds operation out of 75 s lap time. So realistically the motor size will be for a 30 kW nominal load. I see no problem to run the motor at 14,000-18,000 rpm crank speed. Why should the motor not be directly attached to the ICE?
As I have already shown you do not need more than 125 kW nominally to harvest at 250 kW peak power. We would obviously begin at the maximum speed and recover at peak rate of 250 kW although the potential at this point is much higher. We would obviously miss some of the potential but stay with 250 kW rate until the required breaking power drops below 250 kW. I believe you proposed five representative breaking actions in 15 s. This would put us at an average break time of 3 s and a harvest energy target of 460 kJ per breaking. The total budget of breaking energy available in one event is 1.4 MJ. I have plotted the kinetic energy of a 700 kg car between 108 and 252 kph with the blue line. The other lines are for higher or lower weight.xpensive wrote:Again, to charge a battery with 2.3 MJ over 11-12 seconds you will need an average of 200 kW and an awful lot more initially, probably as much as 400, when kinetic energy goes with the square of the speed and power is force times speed.
I fail to see the feasibility of neither such an MGU nor battery.
However, if you include 4WD-KERS (4 * 100 kW), with one MGU at each wheel and 90 kg of batteries (6 * 15) for 2.3 MJ,
it would be technically possible, but such an F1 car would not look or behave like anything we ever seen on track.
If we assume that the deceleration is linear we can easily find from this graph how much energy needs to be absorbed in the first , second and third second.
1. second: 1715 - 1124 = 591 kJ
2. second: 1124 - 657 = 467 kJ
3. second: 657 - 315= 342 kJ
total...............................1400 kJ
We see from this simple example that at all times we can harvest in excess of 250 kW. This means that our peak 250 kW generator needs to be assisted by the friction breaks and the drag to do the job. We are on a pretty safe side and we actually could drop our MGU nominal power to 96 kW to harvest with the peak power rate of 192 kW.
