For a lot of electrical and mechanical machines, there are nominal and peak ratings for energy output or input. If you’re in marketing or advertising, you’ll typically look at the peak rating and move on with your day. But engineers need to know that most things can only operate long term at a fraction of this peak rating, whether it’s a power supply in a computer, a controller on an ebike, or the converter on a wind turbine. But this electric motor system has a unique cooling setup allowing it to function at nearly full peak rating for an unlimited amount of time.
The motor, called the Super Continuous Torque motor built by German automotive manufacturer Mahle is capable of 92% of its peak output power thanks to a unique oil cooling system which is able to remove heat and a rapid rate. Heat is the major limiter for machines like this; typically when operating at a peak rating a motor would need to reduce power output to cool down so that major components don’t start melting or otherwise failing. Given that the largest of these motors have output power ratings of around 700 horsepower, that’s quite an impressive benchmark.
The motor is meant for use in passenger vehicles but also tractor-trailer style trucks, where a motor able to operate at its peak rating would mean a smaller size motor or less weight or both, making them easier to fit into the space available as well as being more economically viable. Mahle is reporting that these motors are ready for production so we should be seeing them help ease the transportation industry into electrification. If you’re more concerned about range than output power, though, there’s a solution there as well so you don’t have to be stuck behind the times with fossil fuels forever.
Thanks to [john] for the tip!
So if it can run continuously at X watts, why can’t you push it a little further for a short period? Is the peak power limited by other (mechanical?) factors?
The article says it can run fulltime at 92% its peak power. It means you have a 8% margin where you can get more power for a short time, as I understand it.
You can, that’s the entire point. The max power is limited typically by voltage rating, but you usually can’t run at that due to heat dissipation. The max could also be a mechanical max.
For a drivetrain there are plenty of times you’d want to run at higher power for short bursts.
I wondered a similar thing. “Peak” is a vendor specified value. If you want to advertise “can run at peak 99% of the time”, just specify “peak” a little lower then usual.
“I wondered a similar thing. “Peak” is a vendor specified value. If you want to advertise “can run at peak 99% of the time”, just specify “peak” a little lower then usual.”
Having different ratings for different time periods is super-common. Modern computers have it, it’s why they thermal throttle. FETs have it, that’s why you have different curves on the SOA (safe operating area) plot. Fuses have it, that’s why you have to take into account surges as well.
This is just the difference between a FET with a SOA plot where the curves from DC to 100 us change quickly (you need to derate a lot more for continous operation) versus one where they change slowly (you barely need to derate at all).
Motors are usually spec’d at 5-10 seconds and continuous. Some give you more data points. If you’re a manufacturer and you specify the 5-10 second mark much lower, you’re a dope because you’re de-spec’ing the motor pointlessly.
Raise the voltage too high and the insolation in the coils will fail. There is a limit and that limit is not just heat. Just depends which of the many limits sets the lowest bounds.
Since these are electric motors, peak power may be limited by magnetic saturation of the iron field paths. Beyond a certain point you can push more current in, but the output torque doesn’t increase that much or at all.
Who would want to be stuck behind a truck going up a pass at 92% of it’s absolute maximum?
Me! If the pass is long enough for you to get annoyed being stuck behind it, it’ll be running at continuous rating anyway. I’d sooner that’s 92% maximum than 50%.
Peak is a 5-10s rating. That’s for acceleration – starting off and overtaking.
Take that Tesla!
The value of the “peak” is a fuzzy definition isn’t it?
For this article you could also state that with this new “unique cooling setup” the peak power value was underrated and therefore it could be used continuously, I’m pretty sure it still has a peak, it’s value just has shifted.
Peak power might be defined as the high point of the torque * rpm curve at the rated voltage.
I expect and hope that this is exactly what they mean: that you can operate this with 92% duty cycle at the peak power that the motor can produce.
As noted before, the “peak power that the motor can produce” depends on how quickly you want to degrade the insulation in the motor windings by applying more voltage.
Often electrical motors can be over-driven by 3-4x the rated power until they either overheat or the insulation breaks down and the motor shorts out.
No, peak isn’t that fuzzy.
There are several factors that limit peak power.
A, B, and C.
B and C are hard limits that do not effet duty cycle.
But A, the ability to remove heat, does effect it.
This hack doesn’t improve peak power.
It vastly improves the survivable duty cycle.
Prior to this, a 5hp pump rated for 100% duty cycle was likely a 25hp pump by electric standards, because heat was always the biggest limiter.
This method might allow an electrically limited 5.5hp pump to run at 5hp continuously.
Well, that’s not a “peak power” anymore but they designed a new motor (old + improved cooling) with a higher rated power. And the peak power of it is still 8% points higher …
This “peak power” talk is just stupid marketing BS
Question is: of what peak? Peak of your diesel engine? Hydraulik pump thingy? Pipes? Hydraulic motor thing? (Thinking of a conventional hydraulic driven farm/forst/work device.) Electric Motor thingy? Bearings? Wiring? Bearing fluid system? Control electronics?
All chained after ech other and all depending on each other… Peak is the limit that the weakest part can handle.
And they shiftet one limitation up to a higher level.
So marketing bullshit.
I think it is pretty clear what “peak power” (along with things like “duty cycle”) means when one talks about an electric motor. That is an established engineering term and has nothing to do with the rest of what you are mentioning.
Whether the rest of the assembly (one rarely uses a motor alone) will handle the increased power or whether even the motor itself will survive it long term due to the increased mechanical wear and tear (cooling is only one part of the equation) is a different problem. I am also rather skeptical there. We have seen this “downsizing” trend in the combustion engines for a long time. With the result the smaller engines being cheaper to manufacture and easier to make fulfill the emission standards – and dying left and right prematurely because they can’t handle the extra load long term. But that’s the customer’s problem …
“and dying left and right prematurely because they can’t handle the extra load long term.”
Yeah, I don’t buy this. The most common engine failures you hear about aren’t due to high load failures, they’re due to stuff like poor thermal management or the designer cheaping out on a critical part (rings, most specifically, but also stupid stuff like timing guides or pumps).
An engine truly failing due to high stress would be like throwing rods or something. Mostly it’s just cascading failures due to dumb design decisions that would happen on engines of any size.
Those things do happen. The turbocharged 3-cylinder 1.0 liter monsters tend to break a piston rod, or snap an axle in the transmission that is not sized to handle the torque vibration for too long.
No, I know they happen, I just don’t see it increasing recently. If anything it’s the other way around.
Do you want to know how I know there are no dealer mechanics in your friend/family group?
Answer: You aren’t hearing about extremely common engine failures.
Hint: From a Honda/Acura tech, nothing newer than 14 from them.
That’s when they stopped putting steel cylinder liners in their motors.
Just running the rings on Al.
Genius!..Lets copy Vega engines from the 70s.
Engines don’t just fail catastrophically due to high stress. They just wear out faster. Ask anybody who’s ever built a thumping V8. Double the power, halve the life. Good tradeoff IMHO.
Doubling the power is what the car manufactures have done to put turbo 4 bangers in full size trucks.
That and the torque converter stall RPM needed to make that kind of shit sandwich move at all.
Makes for a bad time.
But not worse than a 3 valve Ford V8. Those sucked too.
Nope. Very wrong.
Literally every car I’ve had for the past 15 years has an engine that’s been rebuilt. I know what goes wrong in them. For Toyota, for instance, 90% of their issues have been rings. It presents differently (Prius gen 3 head gaskets) but it’s the rings.
To be clear: there’s a difference between a design error and an engine being under designed for the load. Cylinder wear issues aren’t a load issue. It’d always suck.
The Prius G3 issue is a good example. They all blow head gaskets, and it’s always in the same area due to differential heating. So some people will say oh, the engine’s too small and always under heavy load. Except it’s not: the engine wears because the EGR clogs and starves a cylinder. And it’s not the EGR either: it clogs because the rings were cheaper out on (on tons of models) and the oil blowby clogs it.
It’s always dumb stuff.
The thing that’s wrong with a Pius?
Your car watches ‘The View’. (a burn I heard somewhere, but shoe fits)
Also:
You…’Every car I’ve had for the past 15 years has an engine that’s been rebuilt.’
and…’I just don’t see it increasing recently…’
Are you an AI?
Turing!
You don’t rebuild an engine that fails due to load, you throw them out. You rebuild engines that have stupid issues. Rebuilding an engine with a thrown rod would be insane, it’s destroyed.
Or literally every surface that can wear, wears out faster than you expect. There’s always an intended lifetime with such things, but sometimes you can’t hit that because it turns out your lubrication isn’t enough at idle and your lifters can begin to stick, wearing out your cams.
Huh? Peak power for an electric motor is just its max power at rated voltage. How is that fuzzy?
Sure, rated voltage is a bit fuzzy, but it isn’t marketing BS, it’s engineering safety margins.
OTOH, heat is one thing – but the motors aren’t rated as they are only because of heat but also because running 100% at peak power would put too much mechanical strain on the assembly and massively reduce the lifetime of the aggregate.
It reminds me of the Ford EcoBoost – a 1 liter engine that is brought up to usable power levels by turbochargers and what not. With the result that these engines are dying left and right after only few years of use, in some cases even while the cars are still in warranty.
Bigger motor is not only about better cooling but also bigger bearings, more “metal” in the critical parts, etc. So I would be rather skeptical over claims that one could use much smaller/cheaper motors, “they only need better cooling.” Some manufacturing savings can certainly be made – but probably running the motor non-stop at 92% of the peak power of the original one would do “wonder” to maintenance costs. Of course, those are born by the sucker err customer buying such vehicle …
EcoBoosts dying has nothing to do with power levels, and everything to do with Fords stupid decision to using a wet timing and oil pump belt
The Ford ecocrap dying is not just because of the horrible wet belt system. The engines (all of them not just the 1.0) have a floating cylinder configuration. The bottom of the cylinders are attached to the block but the tops are not. this causes the cylinders to move when in a high stress situation. They are known for blowing head gaskets and and having internal coolant leaks. If you design a robust engine and turbocharge it you won’t have problems. The ecocrap engine are also not rebuildable because the top deck can’t be machined due to the floating cylinders. https://www.youtube.com/watch?v=0yx1-50iqnA Shout out to I do cars!
Wet belts are only half the dumb under the timing cover.
Also timing belt/chain driven water pumps.
So when the water pump fails, it mixes coolant and oil and trashes the motor.
To manufactures 250K+ mile car lives were a problem.
Solved!
20 weight oil!
Hats off to Benz for perfecting the warranty timer…German precision indeed.
The mechanical strain on the motor bearings shouldn’t be that high if the assembly is designed correctly. Putting sideways or axial forces on the motor axis is a bad practice.
Coil heating is often the limiting factor for operation.
I’ll preface this with I am not an engineer. But, working in heavy industry I see motors rated at FLC, or full load current. That is what most consider 100%, in that the motor can run continuously at this value. Many motors are regularly run at 130% to 150% FLC because they have cooling systems to help and are only under that load for a short period of time. We even limit the drives to trip at 200% FLC after a period of time to protect the motor. This may sound cavilear but it is completely intentional and we are running 10 MEGAwatt motors for years without issue. So this article to me says they are basically moving what 100% FLC is capable of, but the motor will still have the same absolute torque limits.
This is all about making a tradeoff. This a smaller motor running at a higher load which needs a special cooling system. Obviously the cooling system is going to increase the mechanical complexity and thus the motor is more prone to failure. The real question is if the overall efficiency of the system is higher and the difference in weight from a comparable motor.