Regenerative systems (KERS)

[galien]

hi safeaschuck
just a little explaination of using MHD
http://ataraxie.free.fr/fr_mhdindex.htm
so it's in french but there is pictures

[Ciro Pabón]

Welcome, galien. We speculated on how the airflow could be redirected by ionizing the air, here.

The air wing

Tomislav posted this, in page 4 of that thread, that I think resumes the idea:



Is that what you are thinking of?

[DaveKillens]

Ionizing the airflow would have an influence on the direction of airflow. But it takes energy to generate this ionization, and in the end, that power would be tapped off the engine, in one form or another.

[tomislavp4]

If it gives a bigger advantage than those 80hp the kers provides over a few seconds, you can use the energy from braking to ionize the air instead. Off course the regulations wouldn´t permit that but, we can keep on dreaming right

[galien]

Excactly CIRON
I'had not see this previous topic,
it was just speculation about the renault big noze.
Sure the reglementation does not allow that!
Just for speculation again, does the reglementation allow 400kj only for mechanical work, can the KERS consume more that 400KJ for others uses?
Bye.

[Professor]

The 400 kJ refers to the storage limits, i.e. the batteries or super capacitors. That is all the energy that can be stored. The 60kW limit defines how it can be used, at max, to propel the car.

The voltage of the Kers storage battery system, about 300v, makes it impossible to use for other systems. They ar not 300v.

The ouboard starter used to start F1 cars is a 24v motor. The systems onboard are 12v. That is my understanding. I hope others can confirm or correct my understanding.

[xpensive]

There is no limit to how much energy can be stored. There is a 60 kW limit to the storage rate, as well as a 400 kJ/60kW limit to the release per lap. And yes, it's all monitored by the FIA.
This could be difficult to know unless one has studied this thread over the past week.

[Ciro Pabón]

Is there a reason why you cannot connect a 300V source to a 24 or 12 volt circuit using a transformer? Maybe Professor is the ideal person to explain if a CVT (constant voltage transformer, not a continuously variable transmission) could be used as both a transformer and a regulator.

Yes, yes, I know they're used for AC, but I think that, in this way, the KERS could be used as generator/regulator/isolator/shortcircuit protector (the CVT allows you to do all that, I think), perhaps saving some weight. A DSC rectifier and presto! ...altough something in the back of my mind tells me that regulations forbid it and/or it has been discussed and discarded in this thread. I have not the slightest idea of how an F1 car electric circuit works, except for the ECU (but that's electronic). My ideas about how to put all this together are rather vague, btw, I have only notions.

[tomislavp4]

I think have read some text about the Chevrolet Volt and it said that they try to make all the systems run on the same voltage because using transformers leads to lower efficiency. That may be one of the drawbacks, I guess...

[axle]

Leading on from one of the other comments...

Could a driver bump start an F1 car with a charged KERS device? If KERS mechanically attaches to the engine I'd say definately, if it's attached to the gearbox it would depend on the scenario and which side of the clutch it was for that scenario.

So you stall on the grid, but charged KERS on the warm-up, can you then get away...will teams have thought of that or are they not allowed by the rules?

[xpensive]

I have amused myself with cracking some numbers on how much energy an F1 car consumes around the track, as well pondering opportunities to make it "greener".
Nice even values are used in order to simplify things.

At racing speed, most of a car's losses are to overcome air-resistance, where an F1 car with a Cv-value of more than 1.00 should need some 220 kW at 220 km/h, which with a 90% drivetrain efficiency including rolling resistance means 250 kW. If you took that car around the track for one minute and 20s, the energy used would be 20 000 kJ.

Important note: When the power needed to propel an object through the air increases with the cube of the speed, the above is very much a rough estimation.

Other than that, we need to accellerate the 700 kg car from 100 to 250 km/h FIVE times over that one lap, which is another 7000 kJ for a 700 kg object. A total of 27 000 kJ of energy equals roughly 0.75 liter of gasoline, but with an estimated 20% mechanical efficiency of the engine, we would need 3.75 liters for that one lap.

The end result seems reasonable to me, though greatly simplified of course, but how would you go about it to make F1 "greener"? Anyone?

[ISLAMATRON]

I have amused myself with cracking some numbers on how much energy an F1 car consumes around the track, as well pondering opportunities to make it "greener".
Nice even values are used in order to simplify things.

At racing speed, most of a car's losses are to overcome air-resistance, where an F1 car with a Cv-value of more than 1.00 should need some 220 kW at 220 km/h, which with a 90% drivetrain efficiency including rolling resistance means 250 kW. If you took that car around the track for one minute and 20s, the energy used would be 20 000 kJ.

Important note: When the power needed to propel an object through the air increases with the cube of the speed, the above is very much a rough estimation.

Other than that, we need to accellerate the 700 kg car from 100 to 250 km/h FIVE times over that one lap, which is another 7000 kJ for a 700 kg object. A total of 27 000 kJ of energy equals roughly 0.75 liter of gasoline, but with an estimated 20% mechanical efficiency of the engine, we would need 3.75 liters for that one lap.

The end result seems reasonable to me, though greatly simplified of course, but how would you go about it to make F1 "greener"? Anyone?

Stipulate a maximum downforce, thus every team will try to make that downforce with the lowest amount of drag. Alow for ground effects which are much more aerodynamically efficient than wings. Moveable aerodynamics like variable cooling inlets... let the inlets get smaller as speed increases. Higher efficiency engines(Turbo + DI). Stipulate a max fuel flow and fuel volume. Finally HERS & KERS.

But those are just the cars... the whole circus is rediculously wasteful... but how green can transporting all that crap all over the world be.

[WhiteBlue]

The obvious route to higher efficiency is to maximise mechanical grip and reduce downforce and the associated drag. The rules should heavily penalise fuel consumption. A good step is to make them carry all the fuel and stop refuelling. The other thing is to gradually reduce fuel flow rates which again will favour those wth lower consumption.

[xpensive]

Welcome back WB, as usual we are in total agreement. 4000cc over 80s should mean 50cc per second on average and reduce it from there?
But I guess full bodywork to reduce air-resistance would be heresy though?

[pipex]

Is there a reason why you cannot connect a 300V source to a 24 or 12 volt circuit using a transformer? Maybe Professor is the ideal person to explain if a CVT (constant voltage transformer, not a continuously variable transmission) could be used as both a transformer and a regulator.

Yup, transformers are only for AC. To convert from DC you need a type of static converter called a chopper (sort of a "Ideal DC Transformer"). They are used for example in motherboard voltage regulators (12V, 5V output) or in compact power supplies (a part of a laptop AC adaptor).
You take DC and chop (switching transistor on and off) in a sucession. Next, this is filtered with a low pass filter, to get the DC component. Depending of the amount of time the switches are on, is the voltage you get. In a simple buck converter (used to reduce voltage) the duty cycle (the amount of on time in terms of switching period) is given by:

So, in the example you need a buck regulator using a duty cycle of:

This type of converters are ultra small, at least for providing reasonable outputs 100-200W for small electronic devices.
To get voltage regulation for ample variations of loads and disturbance rejection you use some kind of closed loop control.