Ferrari Power Unit Hardware & Software

[Nonserviam85]

At what times other than under braking does the mgu-k acts as a generator?

Any instance the Counter Electromotive Force produced by the MGU-K is higher than the incoming Voltage from the battery.

well yes ....
the 'incoming' voltage wave magnitude will be ideally varied so that the K can supply/draw any torque at any rpm (within limits)
not just +- 120 kW amountsworth of torque
this will be a waveform in shape ideally matched to the field flux
there will be generated current output to the DC line when the 'CU' onboard capacitor voltage exceeds the ES voltage

the K is a PM 'electronically commutated' machine or a PM synchronous machine - the H is a PM synchronous machine
the machines are under continuous closed-loop(s) velocity (or velocity + ano) control between the machine and its CU
the demand signal to the CU is continuously produced by the PU torque demand : torque output map
(btw what the FIA calls the CU is in the real usually called something else)

I was just trying to explain in simple terms the fundamental principle of regen from a motor/generator unit.

Obviously it is more than that but you are generally right, however some of your terminology is wrong.

[henry]

You're better off lifting later and harvesting as well in that case, energy lost to drag is wasted.

But you don’t have the fuel to lift off later, and consequently you can’t input the energy to harvest.

[PhillipM]

You'd use more fuel lifting off earlier and not recovering than you would lifting off later, recovering, and then using that energy out of the next corner with the engine in a lower mode.

[saviour stivala]

Any instance the Counter Electromotive Force produced by the MGU-K is higher than the incoming Voltage from the battery.

well yes ....
the 'incoming' voltage wave magnitude will be ideally varied so that the K can supply/draw any torque at any rpm (within limits)
not just +- 120 kW amountsworth of torque
this will be a waveform in shape ideally matched to the field flux
there will be generated current output to the DC line when the 'CU' onboard capacitor voltage exceeds the ES voltage

the K is a PM 'electronically commutated' machine or a PM synchronous machine - the H is a PM synchronous machine
the machines are under continuous closed-loop(s) velocity (or velocity + ano) control between the machine and its CU
the demand signal to the CU is continuously produced by the PU torque demand : torque output map
(btw what the FIA calls the CU is in the real usually called something else)

I was just trying to explain in simple terms the fundamental principle of regen from a motor/generator unit.

Obviously it is more than that but you are generally right, however some of your terminology is wrong.

Thank you, appreciated. admits that some of my terminology might be wrong.

[subcritical71]

I should have said the 'lift and coast' scenario causes the lights to flash at the beginning of a possible generating scenario (as the MGU-K is going from 120kW deployment to neutral, or no deployment).

IMO K should never be neutral. In order to minimise a lap time, it should always either deploy or harvest.

Yes, I agree. But the wording of lift and coast is only a reduction of 120kW. It was hard to convey my sentiment, but what I was thinking was if you back off the MGU-K by 120kW you are essentially going to be generating a short time after that. As Henry mentioned also, the output + or - of the MGU-K would be proportional to the torque demand and not on or off.

[henry]

You'd use more fuel lifting off earlier and not recovering than you would lifting off later, recovering, and then using that energy out of the next corner with the engine in a lower mode.

If you don’t have enough fuel you can’t use the K to slow you because you would need to keep the throttle open a little longer to arrive at the end of the straight, braking point, at the same time as lift and coast. On the next straight you might well be able to use the K a little longer, but you still have a deficit.

The K allows you to save energy in one place and deploy it later. But if you don’t have the energy to save you don’t have it to deploy later.

[PhillipM]

If you were that low on fuel you'd be even more wanting to recover what you can instead of wasting the energy in drag. That boost of acceleration at the start of the next straight would more than make up for deliberately running the engine in a lower mode for the rest of it.

[saviour stivala]

You'd use more fuel lifting off earlier and not recovering than you would lifting off later, recovering, and then using that energy out of the next corner with the engine in a lower mode.

If you don’t have enough fuel you can’t use the K to slow you because you would need to keep the throttle open a little longer to arrive at the end of the straight, braking point, at the same time as lift and coast. On the next straight you might well be able to use the K a little longer, but you still have a deficit.

The K allows you to save energy in one place and deploy it later. But if you don’t have the energy to save you don’t have it to deploy later.

Producing energy by burning fuel so as to be able to harvest it is legal and still done under braking (using the brake pedal and throttle together) it is mostly resorted too by those whose MGU-H/TURBO combination is incapable of harvesting at least 50% of ES needs. From what was being said by people that matters, the top/best MGU-H/TURBO combinations can harvest at least a minimum of 60% of ES needs over a lap.

[hurril]

You'd use more fuel lifting off earlier and not recovering than you would lifting off later, recovering, and then using that energy out of the next corner with the engine in a lower mode.

If you don’t have enough fuel you can’t use the K to slow you because you would need to keep the throttle open a little longer to arrive at the end of the straight, braking point, at the same time as lift and coast. On the next straight you might well be able to use the K a little longer, but you still have a deficit.

The K allows you to save energy in one place and deploy it later. But if you don’t have the energy to save you don’t have it to deploy later.

You are conflating two things here. Lifting and coasting does not even have to engage the K to save fuel. You are cutting time under WOT and that will save fuel. Even engaging the K during the coasting is just compensated for by not having to throw away as much energy using the brakes.

[saviour stivala]

When the K harvests energy under braking, energy which otherwise would have gone to waste, that energy harvested will contribute to power unit efficiency. When the K harvests energy under braking by burning fuel (which is legal) because the H/TURBO combination cannot satisfy at least 50% of ES requirements, that energy harvested will contribute nothing to power unit efficiency. Ditto for any other mode of harvesting by the K.

[henry]

You'd use more fuel lifting off earlier and not recovering than you would lifting off later, recovering, and then using that energy out of the next corner with the engine in a lower mode.

If you don’t have enough fuel you can’t use the K to slow you because you would need to keep the throttle open a little longer to arrive at the end of the straight, braking point, at the same time as lift and coast. On the next straight you might well be able to use the K a little longer, but you still have a deficit.

The K allows you to save energy in one place and deploy it later. But if you don’t have the energy to save you don’t have it to deploy later.

You are conflating two things here. Lifting and coasting does not even have to engage the K to save fuel. You are cutting time under WOT and that will save fuel. Even engaging the K during the coasting is just compensated for by not having to throw away as much energy using the brakes.

That’s mostly the point I was trying to make. I obviously did a poor job.

[saviour stivala]

You'd use more fuel lifting off earlier and not recovering than you would lifting off later, recovering, and then using that energy out of the next corner with the engine in a lower mode.

If you don’t have enough fuel you can’t use the K to slow you because you would need to keep the throttle open a little longer to arrive at the end of the straight, braking point, at the same time as lift and coast. On the next straight you might well be able to use the K a little longer, but you still have a deficit.

The K allows you to save energy in one place and deploy it later. But if you don’t have the energy to save you don’t have it to deploy later.

You are conflating two things here. Lifting and coasting does not even have to engage the K to save fuel. You are cutting time under WOT and that will save fuel. Even engaging the K during the coasting is just compensated for by not having to throw away as much energy using the brakes.

"Throw away as much energy using the brakes?"

[hurril]

If you don’t have enough fuel you can’t use the K to slow you because you would need to keep the throttle open a little longer to arrive at the end of the straight, braking point, at the same time as lift and coast. On the next straight you might well be able to use the K a little longer, but you still have a deficit.

The K allows you to save energy in one place and deploy it later. But if you don’t have the energy to save you don’t have it to deploy later.

You are conflating two things here. Lifting and coasting does not even have to engage the K to save fuel. You are cutting time under WOT and that will save fuel. Even engaging the K during the coasting is just compensated for by not having to throw away as much energy using the brakes.

"Throw away as much energy using the brakes?"

Yes. Braked away energy is wasted energy and that matters in an energy limited formula.

[saviour stivala]

You are conflating two things here. Lifting and coasting does not even have to engage the K to save fuel. You are cutting time under WOT and that will save fuel. Even engaging the K during the coasting is just compensated for by not having to throw away as much energy using the brakes.

"Throw away as much energy using the brakes?"

Yes. Braked away energy is wasted energy and that matters in an energy limited formula.

Yes it is when harvested by burning fuel, but not when harvested under braking alone, and ditto when the K harvests in any other mode other than when braking.

[Dr. Acula]

"Throw away as much energy using the brakes?"

Yes. Braked away energy is wasted energy and that matters in an energy limited formula.

Yes it is when harvested by burning fuel, but not when harvested under braking alone, and ditto when the K harvests in any other mode other than when braking.

Well, if you lift and coast, you aren't on the throttle but you're also not on the brake. So you don't burn fuel but you also don't slow down the car significantly. You basically just let the car roll. And you can already harvest energy during the lift and coast period and it doesn't do that much to the speed of the car.

Let's say the car has mass of 850kg and a speed of 80m/s (288km/h) when you start to lift and coast. The car at this point has a kinetic energy of 2.72MJ. If we don't look at the drag and the engine braking effect of the ICE and other loses, how much speed would you lose if you apply the full 120kW of the MGU-H for 1 second to harvest this kinetic energy?
well, you would only lose about 1.8m/s or about 5km/h, but it gives you 120kW extra for 1 second more on the next straight.