Hi,
i was thinking about how to create a simulation to model a basic electrical KERS (i won't do it right now, just thinking ), and i don't know how to model the mechanical part of the system. From the electric motor/generator side we have the electrical torque (function of the input current and machine characteristics) and output shaft speed. Then, this electric motor could be connected to the engine crankshaft (it seems that most F1 KERS are done in this way). How could this complex mechanical part could be modelled?. I don't need a complex model, a simple one should be sufficient. From what i can imagine the inputs of the mechanical system could be the accelerator, brakes, and ??? hahaha, don't know . And the outputs could be shaft torque, speed. Any reference you can recommend?. Yes, i'm crazy if you are wondering hahaha.
The motor/generator part of an electrical KERS is the easy part. The difficult part is designing the circuitry and electrical energy storage system capable of the charging/discharging rates necessary in a reliable F1 KERS system.
You can model the mechanical portion of the KERS like any other gear-motor driven mechanical system. You just need to get the polar inertias right.
As for the electrical portion, designing solid state circuitry that can handle the thermal loads of an electrical F1 KERS is no small feat.
Good luck,
Terry
"Q: How do you make a small fortune in racing?
A: Start with a large one!"
Pipex, When I did a control systems course.. I did something similar.. but with just controlling the speed of a simple motor.
I am not the electronic kind of person, so I don't know all the terms. but I would try approach it something like this: (WARNING...I think all over the place)..
The acceleration of the engine I think might not be as critical as when the car is braking.. just make the out put torque from the motor shape similar in output to that of the engine.
The battery..
Some regulator/system that puts in the current.. when the KERS button is not pressed.
Some sensor that tells how much charge is in the battery.
Some regulator/system that discharges the battery when the the KERS button is pressed.
Basically something that controls how fast the battery takes in and releases the energy..
The DC machine (motor)
You have all the equations for Torque, speed, slip etc.
Make the control systems model.. block diagram etc..
A Closed loop system..For when it is a motor, Inputs would be like (i don't remember too well) Input Voltage, Current.. the feedback would be like the back emf, torque..
When it is a generator; Input would be for example the torque, speed, load from charging the battery.. I think** there might be more..
There might be a transformer in there too.
The engine itself.. the worst thing I can think of is the shape of the torque Vs engine rotation graph as the engine is decelerating.. Because the KERS is acting like a flywheel absorbing this energy.. and you have to have some idea of how the input torque curve can be shaped.. Like whether the torque is coming in steady, or if there is a spike.
Hmm.. You have brakes too.. you can find out how much energy from the car is to be left to be taken by the system.. since the brakes are still dissipating some of it.
hmmm..basically how much braking torque the system has compared to the brakes them self. I am not sure of how to make a block diagram for this part. Maybe the input is ring gear speed.
The gearbox inertia is sorta easier.. because it is mostly dependent on the gear that is selected and the speed. So I guess an Input for this would be speed and gear selected.
Then again if you have a proper control system designed.. the system can take car of any variations.. no matter what the engine is doing. All you would have is a basic:
Input torque, motor shaft speed, battery charge, Gear selected, When you are braking. This will tell the system how much energy to take, so the car brakes predictably. When you want power.. The input is the same but you can throw in wheel spin (rpm spikes).
In the end you are supposed to have a system of different equations in a block diagram in a program like matlab or simulink(?) and you feed in the input graphs of how the torque from the engine is behaving etc. and see how it the battery charges.
THis is just me Brainstorming.. rudimentary Ideas.. I am no expert on control systems that's for sure.
Of course if you have a gearbox of my design that is also an integral Kers generator motor, it becomes far easier.
A complete range of over run braking is available with no ratio steps and the effects of the ICE can be taken out, to be simulated by gearbox control through the electronic system.
Rear wheel braking is then a simple matter to balance and to also maintain front to rear adjustment.
), and i don't know how to model the mechanical part of the system. From the electric motor/generator side we have the electrical torque (function of the input current and machine characteristics) and output shaft speed. Then, this electric motor could be connected to the engine crankshaft (it seems that most F1 KERS are done in this way). How could this complex mechanical part could be modelled?. I don't need a complex model, a simple one should be sufficient. From what i can imagine the inputs of the mechanical system could be the accelerator, brakes, and ??? hahaha, don't know 
. And the outputs could be shaft torque, speed. Any reference you can recommend?. Yes, i'm crazy if you are wondering hahaha.