Thermal Energy Recovery System Generator Motor (MGUH)

[ringo]

This thread is about the MGUH generator motor.
We can look at:

[*]motor types, and how they work
[*]the advantages of those motors
[*]the operating environment
[*]torque and speed characteristics, or even frequency/ voltage
[*]AC or DC

It will serve to be informative to those of us who may be familiar with motors, but to go even more in depth on the uses and real world problems associated with selecting the right motor for the job. I think the 2014 MGUH is challenge, especially at the temperatures and speeds that the motor will operate in.
Also the requirements to have some level of control.
So i guess anyone on F1 who has a lot of knowledge on motors and motor control can kick it off.

[Andres125sx]

A basic explanation of the system will aid the thread


Does the turbine spin continuously? Or there´s a by-pass?

[WhiteBlue]

A basic explanation of the system will aid the thread.
Does the turbine spin continuously? Or there´s a by-pass?

There are two options which in reality will not be used IMO. You can have a clutch which disengages the MGU-H from the turbo shaft. And you can have a waste gate that takes some flow off the turbine and bypasses it into the exhaust.

Both solutions will not be used regularly if it is your intention to win a race. You cannot afford the loss of energy from the MGU-H. So the trick will be to control it properly to make it maximize the available surplus energy from the turbine.

The basic layout will be an AC motor/generator with permanent magnets that will be controlled by an AC/DC inverter that can work in each direction. The primary sensoric control will be a rotary encoder that tells the control electronics exactly the position of the magnets with regard to the position of the coils. This enables the induction control for motor or generator mode.

According to my latest estimates I expect the MGU-H to be rated for at least 45 kW and no more than 100 kW in overload mode. So the standard rating could be 30% lower like 32 kW - 70 kW. The reason is that those water cooled units can be overloaded if they are not utilized by 100%. The standard rating is always for 100% thermal load. If you do only 70% peak thermal load you can overload 30%.

[dren]

Do we know the speeds the motor will see? (I assume the MGUK will be close to 1:1 engine rpm, but not sure what the MGUH will be)

[dren]

http://www.greencarcongress.com/2010/11 ... -7-kg.html

Proposed Honda Set-up for 2009 KERS:

106 cell Lithium-Ion pack

KERS Motor speed range 13,000 to 21,000 (18,000 ICE redline)
Stator Core: AC three-phase, four-pole, twelve-tooth design with a double lap-wound stator
Rotor: permanent magnet
Liquid cooled with oil from engine

PCU cooled with deadicated loop

Motor achieved 7.8kW/kg. Total weight was 6.9kg.

Peak motor efficiency was 99% and peak generator efficiency during regen was 93%.

[flynfrog]

The basic layout will be an AC motor/generator with permanent magnets that will be controlled by an AC/DC inverter that can work in each direction. The primary sensoric control will be a rotary encoder that tells the control electronics exactly the position of the magnets with regard to the position of the coils. This enables the induction control for motor or generator mode.
.

I disagree I would guess its a multiphase DC motor.

[WhiteBlue]

The basic layout will be an AC motor/generator with permanent magnets that will be controlled by an AC/DC inverter that can work in each direction. The primary sensoric control will be a rotary encoder that tells the control electronics exactly the position of the magnets with regard to the position of the coils. This enables the induction control for motor or generator mode.
.

I disagree I would guess its a multiphase DC motor.

And what you are going to use as the generator? AC servo machines with bi directional inverters (using IGBTs) can function as motor and generator. Those are commonly used in robotics, elevator direct drives and automotive applications. In all these applications kinetic energy needs to be regenerated and the motors therefore need to also work as generators.

[flynfrog]

A DC motor can also act as a generator. And wont require the AC to DC conversion twice. Ultra effeceient Solar EVs all use DC motors and have regenerative braking.

[dren]

The Honda used an AC motor, as does the Tesla roadster. What benefits does the DC have over AC? The Honda motor was quite efficient.

[wuzak]

The Honda used an AC motor, as does the Tesla roadster. What benefits does the DC have over AC? The Honda motor was quite efficient.

I would think an AC motor could be physically smaller.

[WhiteBlue]

A DC motor can also act as a generator. And wont require the AC to DC conversion twice. Ultra effeceient Solar EVs all use DC motors and have regenerative braking.

Those systems use tiny power levels compared to F1. Weight and electric efficiency of the machine in Solar EV is of relatively low priority compared to aero efficiency and chassis weight. Electric machines in F1 use typically 100 times the power of a solar EV. If I'm not mistaken electric efficiency of small brushless DC machines is 80% compared to 98% of big AC machines.

AC is used in all high power applications where efficiency is essential. The list is endless: Elevators, robotics, machine tools, automotive, presses, metal and plastic casting machines and even in construction equipment AC machines are starting to replace hydraulics. You do not find any DC in those high power apps. Why should F1 be different?

Brushless DC electric motor (BLDC motors, BL motors) also known as electronically commutated motors (ECMs, EC motors) are synchronous motors that are powered by a DC electric source via an integrated inverter/switching power supply, which produces an AC electric signal to drive the motor. In this context, AC, alternating current, does not imply a sinusoidal waveform, but rather a bi-directional current with no restriction on waveform.

I also consider that we have a misunderstanding. By AC I'm always referring to the type of current the machine is using not to the power supply. The AC machines we are speaking off in F1 all use DC power supply but AC in the machine. Hence the need to use an inverter.
http://en.wikipedia.org/wiki/Brushless_ ... tric_motor

A Brushless AC electric motor is an electric motor driven by an AC electrical input, which lacks any form of commutator or slip ring. Generally the term 'brushless AC motor' will refer to a permanent-magnet synchronous motor (PMSM) or permanent-magnet motor (PMM), a synchronous motor which uses permanent magnets rather than windings in the rotor. PMSMs are either axial flux, radial flux, transverse flux, or flux switching depending on the arrangement of components, with each topology having different tradeoffs among efficiency, size, weight, and operating speed.

Alternative designs may use reluctance rather than magnets. Asynchronous induction motors are also brushless AC motors.

The brushless DC motor is a brushless AC motor with integrated inverter and rectifier, sensor, and inverter control electronics.

The bolded sentence could indicate that we are talking about the same thing here. We may be using different definitions in the US and EU.

[flynfrog]

I think you maybe correct WB I think we are confused on terms talking about the same thing. The "DC" motors we used could be driven with a sine wave in 3 phases. They pushed into 98% efficient across a pretty good usage range. The controllers were made up of 3 pretty large H bridges to move the energy around the coils. The magnets were mounted to the rotor coils on the stator side.

[WhiteBlue]

I'm happy we have cleared that up. I usually take it for granted that once you use a universally capable inverter it makes no difference if your power source is DC or AC. The inverter will take it all and chop it up to the right AC form that is needed to drive the machine in motor or generator mode. Inverters that use DC links are generally used in the automotive and robotic industry because you can feed the regen from one machine to another one or store it in a battery or supercapacitor. F1 will not be any different in that regard.

The biggest difference I see is the weight optimization. These guys are seriously overloading the KERS machines they use today, because the relative thermal load is so low. It will be relatively much higher in 2014 particularly in qualifying when the MGU-K is loaded by regen braking, ES maximum feed and the HGU-H feed.

[ringo]

Why the clutch or waste gate will be necessary is that the energy stored is not allowed to be charged in the pit lane.
If your engine is running or you are acceleration out of the pit lane, you will need to disconnect the generator from the turbine shaft. Or you may also consider opening up a waste gate.

As for the encoders, i see a potential issue with the temperature. Encoders are usually axially located. If the motor is between the turbine that will pose an issue.
Due to this concern i feel that Renault's solution is very smart. Keep the generator out of the high temperature area by the turbine. They have the generator ahead of the compressor, and it's quite likely that the encoder is on the opposite end of the compressor; even further from the heat of the turbine.
The motors may be 3 phase for sure, very similar to the KERS motor in fact.

Now because it is spinning at over 100,000 rpm. I would like us to investigate how the speed impacts on the size of the generator and also physical characteristics.

[wuzak]

Why the clutch or waste gate will be necessary is that the energy stored is not allowed to be charged in the pit lane.
If your engine is running or you are acceleration out of the pit lane, you will need to disconnect the generator from the turbine shaft. Or you may also consider opening up a waste gate.

Running in the pit lane the engine will be at low rpm and/or at idle. The MGUH will not be connected, as you say, but not because it isn't allowed to store energy in the pit lane. At those engine speeds the turbine is unlikely to be making power in excess of that required for the compressor. Having the MGUH would just be a drag on the turbine. No waste gate would be required in that situation.

The rules don't allow energy to be added to the ES during the race or qualifying by external sources. I suppose that the MGUH and MGUK could still generate energy to store, but it is unlikely that either will be able to produce any significant amount of energy.

As for the encoders, i see a potential issue with the temperature. Encoders are usually axially located. If the motor is between the turbine that will pose an issue.
Due to this concern i feel that Renault's solution is very smart. Keep the generator out of the high temperature area by the turbine. They have the generator ahead of the compressor, and it's quite likely that the encoder is on the opposite end of the compressor; even further from the heat of the turbine.
The motors may be 3 phase for sure, very similar to the KERS motor in fact.

The point is quite valid. Heat will be a significant problem to deal with in 2014. Having the MGUH ahead of the compressor, as in the Renault's layout, makes sense from a cooling and packaging standpoint.

On the other hand, the required position of the exhaust outlet is a long way behind the turbo outlet. So having the MGUH between the turbine and the compressor will push the turbine further back and shorten the exhaust pipe from the turbo outlet. Whether this makes any difference to engine performance is unknown to me.

The problem with that solution is that the sizeable turbine housing may cause problems for aerodynamics.