It will control the turbo shaft speed, which controls the boost produced. Which is exactly what the wastegate does - in a different manner. It controls shaft speed by reducing the amount of power the turbine produces.ringo wrote:You have it for electric power generation. It cannot limit boost. It will only retard the time it takes to come up to max boost. This requires power.
The boost of the compressor is related to its rotational speed. Controlling its speed is what the MGUH does.ringo wrote:You may see this a boost limiting if you use it as a load on the turbine, but in truth it's really a turbine brake more than anything else. So you may interpret this as a limit, but it's not, it is retardation.
It is this retardation that will require a lot of research and testing and fine tuning. You can't instantly cut off boost with this thing. It will have to instantly resist the turbine and then easing up at exactly the right time, with the right level of retardation to maintain a steady turbine speed, all of this happening while back pressure and temperatures increase.
You can't instantly cut off boost with a wastegate either - there is a delay, though that may be small.
I'm not up to speed with electrics, but I believe that they could bring the turbine to a dead stop if they wanted - very bloody fast!
And a waste of precious energy.ringo wrote:A true boost limiter is a waste gate. It is not a load, it is a relief that reduces mass flow through the turbine. Quite simple and more direct. Very smooth and straight forward.
You are allowed ~4,600 MJ of energy per race, and you are going to throw away 100MJ+? Or 2%. Doesn't sound a lot. But when you are already throwing ~65% away in the ICE, you are losing 100MJ from ~1,600MJ of race energy usage. Or ~6%.
The MGUH only takes off the excess power not required for the compressor. That is, if the turbine is making 100hp, for argument's sake, and the compressor requires 80hp, the MGUH will only take off 20hp.ringo wrote:What we must realize is that the MGUH is no different than the compressor. All it does is compete for turbine power.
But what complicates things is that it shares a mechanical connection to the compressor, it is not a free power turbine like a helicopter engine, where different loads need not run at the same speed.
You will find that what you take off in power for the MGUH may not correspond to what you would like to take off in power for the compressor as these power draws give different outcomes at a certain shaft speed.
Using the controller this can be done very precisely and adjusted very quickly.
I'm not sure what you mean by load it with the battery or MGUK?ringo wrote:There is going to be a tricky balance if the MGUH is used to slow the turbine to control boost.
You can slow the turbine by loading it with the battery or the MGUK, or you can use the battery to drive the MGUH magnetic field in the opposite direction.
The MGUH will only see the controller. The controller will convert the current to DC for storage in the battery. Or it will convert it for use by the MGUK - I'm not sure if this will involve a rectifier and inverter (MGUH and MGUK frequencies will probably rarely be matched).
The amount of energy that can be transferred between the MGUH and MGUK is unlimited. The amount of energy that can be transferred to the batteries is between 2MJ (full MGUK braking recovery) and 4MJ (no MGUK braking recovery).ringo wrote:There is going to be a tricky balance if the MGUH is used to slow the turbine to control boost.
You can slow the turbine by loading it with the battery or the MGUK, or you can use the battery to drive the MGUH magnetic field in the opposite direction.
Load the turbine, with the MGUH behaving as a resistance. The power drawn must be sent through to the batteries. This easier for boost control because the power is unlimited, The batteries physical limitations for recharge rates will have to tie into your turbine boost control. Very tricky.. If the rate is higher than the power required the MG controller can meter the MGUH loading.
If it's going through the MGUK now, or to something to power a 12v dc load on the car, it must go through the MG control unit. Now this is unlimited, but the truth is it really isn't. The MGUK can give only 120kW to the drivetrain. The unlimited stuff goes back to the batteries. In the event you want control boost and your energy store is full. The MGUH must draw a specific amount of power, to create a specific amount of load on the turbine to give a specific turbine speed to limit boost. You have up to 120kW to do this. If the turbine needs more than 120kW to slow it down, your goose is cooked, you should have shed power off your batteries. Can you predict this? nope! lol
There isn't a size limitation to the MGUH. It can take all the load that the turbine can give.
Also, the controller is probably clever enough to be able to push 120kW to the MGUK and send any remainder to the battery. Personally I can't see the MGUH ever producing 120kW+.
The turbine will be sized to take into account the size and capability of the MGUH.
Electric machinery can be very precisely controlled. And it can be adjusted very quickly.
Like every system on an F1 car. There are feedback sensors to everything, though some aren't allowed to be actively used for control (thinking things like traction control), but can be sent back to the pits in a telemetry burst, or logged for review later.ringo wrote:Now using the loading method is quite difficult and i don't think teams will go that route as it's very dependent on what the car is doing on track and the ES state. It's basically playing an all knowing being, a lot of headache to figure out just to control a stupid little compressor. This loading method is less stressful and is more natural but really requires God like awareness of the whole energy system and car to control turbine shaft speeds. Closed looped system with speed sensor tied into the various loads; battery, ancillaries and engine load, will be required.
I don't think all these systems need to be "all knowing". They need to know what the throttle pedal is doing - already signals for that, they have been using electronic throttles for years. And they need to know what the ICE is doing. They have traditionally had sensors for everything, and will continue to do so.
When the power requirement (throttle) and current engine conditions are known, the values for boost, fuel flow rate, etc, come off a map. That map will tell the computer how much power will need to be drawn from the MGUH in order to maintain the correct boost.
Honestly, I think you are making it sound more complicated than they are. Of course the devil is in the detail - getting the systems working as intended will take some tuning and experimentation, working to define and refine the maps.
I have no idea what you said there!ringo wrote:The other method is attempting to reverse the turbine against exhaust flow.
What i mean like this is to drive the MGUH magnetic field in the opposite direction with the batteries with a certain power lesser than the shaft power. The net torque will be what determines your limited turbine shaft speed. This is most unnatural, as it's a counter action more than a load. However it's easier to do since the battery is isolated from the rest of the loads around the car. The engineer need only look at the unlimited battery to MGUH path as a boost control. Is it worth using battery power to limit boost? Why use your precious energy to control a turbine? Well if what is dumped through the wastegate, is less power than the battery energy required to brake a turbine, then i'd dump it.
If it's less power to use the battery, then i'd consider it but many other factors have to be looked at like temps. response time.
But, to reiterate, there is no pwer limit on the MGUH, but there is an energy limit to how much can be dumped in the battery pack.