New 2-In-1 EV Motor Is Genius Or Maybe Not

NOV 7 2014 BY MARK KANE 20

Promising new engine undergoing further improvements for eventual commercialisation

Promising new engine undergoing further improvements for eventual commercialisation

2-in-1 motor which integrates the traditional electric motor with the air-con compressor

2-in-1 motor which integrates the traditional electric motor with the air-con compressor

Who wouldn’t like to get 2 for 1? That’s probably what scientists from Nanyang Technological University (NTU) and German Aerospace Centre (DLR) thought while developing a new 2-in-1 electric motor for electric cars.

It integrates electric motor with A/C compressor and the compressor drive motor in a single housing. The compressor drive motor is engaged via clutch during braking event, which according to the team will improve overall efficiency, increasing range in hot climates by up to 15-20%.

“The new 2-in-1 design allows the electric motor to be more efficient in powering the car’s wheels, while its integrated air-con compressor uses less power due to synergy between the engine and the compressor, which can also tap on energy regenerated directly from the car’s brakes.”

Well, electric cars are typically recovering most energy from braking, so using kinetic energy to propel an A/C compressor will only be slightly more efficient (less energy conversions). We don’t think 15-20% range gain is really possible.  Maybe 5%?

Moreover, we believe this device has some drawbacks.  How will the A/C operate efficiently if we are not braking much?

“Based on simulations and analysis, the team expects the system to reduce battery consumption by at least 3% compared to existing mechanisms while improving the regenerative energy capturing capacity of the system by 8%.”

Prof Subodh Mhaisalkar, Executive Director of the Energy Research Institute @ NTU (ERI@N), stated:

“The biggest challenge with electric cars in tropical megacities is the range that they can travel on a full-charge, because their batteries are needed to power both the engine and the air-conditioning. In tropical countries like Singapore, up to half the battery’s capacity is used to power the air-conditioning system.”

“With the global population of electric vehicles set grow rapidly to 20 million in 2020, a more efficient electric motor cum air-con compressor, will enable cars to travel further on a single charge. This energy efficiency will in turn reduce overall greenhouse emissions and promote sustainable transportation solutions.”

“This integrated design solution for air conditioning will go a long way in reducing the range anxiety of drivers, reduce maintenance costs, and will save time and money for the driver.”

This work won the Best Originality Award in the TECO Green Tech International Contest held in Taiwan. German Aerospace Centre will conduct further tests and improvements before of eventual commercialization.

Dr Michael Schier, from DLR’s Institute of Vehicle Concepts, remarked:

“For electric vehicles, the air conditioning uses a lot of electrical energy, thereby cutting down the range of electric cars by up to 50 per cent. To increase the energy efficiency and therefore the range of electric cars, the thermal management and the integration of additional functions into existing powertrain components play a major role.”

“By integrating the refrigerant compressor directly into the electric motor, we save components, weight and cost. Simultaneously, the more regenerative braking part of the kinetic energy is passed directly to the refrigerant compressor and thus the efficiency is further increased.”

Research scholar Mr. Satheesh Kumar from the Energy Research Institute @ NTU said his award-winning, integrated electric motor challenges conventional design that goes way back to the 1960s when air-conditioning first became popular:

“Back then, air-conditioning was something new that was an add-on feature to a car’s combustion engine,” said the 29-year-old Singaporean.

“Since we are now designing electric vehicles from scratch, I see no reason why we should keep both units separate. As we have proven, combining the two gives us synergy – a more efficient use of electricity and it also improves engine braking, which stops the car faster with lesser wear on the brake pads.”​

Source: NTU via Green Car Congress

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20 Comments on "New 2-In-1 EV Motor Is Genius Or Maybe Not"

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This is how AC compressors work on normal cars. The compressor is driven by a belt attached to the motor.

Color me skeptical too.

I’d think that whatever little this system might gain during regen braking would be offset by the lower average efficiency of the compressor forced to run at whatever speed the motor is… wouldn’t it?

WOW 50% reduction in range for an EV when the A/C is switched on. Really? If the A/C compressor is integrated into the drive motor how do you get A/C when the vehicle is not moving like when you are sitting at a traffic light.

False, on all count1
The a/c might be a big load for combustion car because they are externaly engine driven at a pace that is not optimal for a/c.
On an electric car it’s driven by it’s own fully variable speed completly sealed cooling loop motor that adjust it’s output to the need.
In fact, it need between 500 watts to 1 Kw maximum.
So much, that I don’t turned it off on summer because it has insignificant impact on range.

AC cuts EV range by “up to 50%”? Really? What the heck EV are they talking about? On my Leaf it’s about 8%.

There’s nothing like a little funny accounting/overblown claims to instill confidence in people when you’re announcing a “breakthrough”…

Um…if this article was about electric heaters using 50% of the energy on a drive…I’d almost believe it.

I crank my AC all summer long, and while I do notice a slight range drop, it’s not nearly as significant as using the heater, and no where near 50%. I’ve had the AC set to it’s lowest setting on 115 degree days, and noticed *maybe* a 10% range drop on my Volt. Even then, I still got 40 miles, not my usual 45-50.

My sense from the post is that the A/C compressor supplements its draw on the battery with kinetic energy from breaking. This makes sense to me, because regenerative breaking only recovers a percentage of total kinetic energy (no matter what my ford break coach display tells me). If more of the kinetic energy can go directly to the compressor, this would be more efficient. Even if the gain to range is slight, there’s still no reason to not have it.

The reason to not have it is complexity. One of the major reasons older cars needed so much maintenance was that everything was connected to the engine. This required complicated belt systems to connect everything, meant that most things were being run all the time, and meant that everything ran at the engine’s speed instead of at its own optimal speed. Micro-hybrids get around all of this by having a larger alternator and running everything except the wheels off of motors. This ends up reducing the complexity considerably, which leads to higher efficiency and lower maintenance. It is unlikely that a minor efficiency gain is possible by directly linking things to the motor of an electric car without substantially increasing the cost, reducing the effectiveness of whatever is driven by the motor, or making the whole car less reliable. If you want to be able to control the A/C output, then this might even reduce efficiency. Also, a car A/C should use less than 400W. I can cool an entire room in my house (about 1000 ft^3) with a 500W A/C. The only time you would need much power is when the car is at 120F and you want to… Read more »

Seems to me that the simplest solution is to just shunt regen energy to the AC compressor instead of charging battery (and then excess not used there then carries on to battery)

Then it can stay a separate (reliable) module and still get the slightly more efficient AC use.
Integrating everything into the drive motor is just a step backwards towards the ICE era.

Agreed, but just to keep things in perspective: regen can be in the tens of kW, whereas an electric A/C compressor would be at least an order lower at maybe 1~2 kW.

I’m not even sure that purposely pushing more power into the A/C during braking, effectively reducing battery charging current by only ~5%, would even compensate for the higher losses (not to mention wear) in the compressor now rapidly ramping up then down…

As this is clearly only an issue in hot climates, the AC could be oversized to be able to make this system worth while (or, you know, just don’t bother for such miniscule returns ;))

E.g. similarly to how volt stores heat in coolant instead of heating air directly, a large AC could be cooling a pool of liquid, which is when tapped into for regular cooling at a lower level.

I’d just go the ‘why bother’ route, personally. AC just isn’t a huge draw. But maybe it’s perspective in terms of mild summers here.
In some hot parts of the world, AC running full blast and slow moving traffic, I could see how it’s an issue.

I can see where using regen for a/c would reduce conversion losses. But only where a/c is the main use of power. Like above 100F ambient. All other scenarios are potentially less efficient than a dedicated a/c drive motor.

The only potensial i see is to scale it up and use it for a future electric aircraft. That might save a bitt of weight, and you could use the bleed air for de-icing and running the packs. Having the compresor in the same housing might save some weight

Man oh man Mark Kane you are easily impressed! This technology ‘advance’ happened around 80 years ago. Ever hear of a ‘Frigidaire’? – That’s the so – called ‘Full Hermetic’.

There is also the so-called “Semi-Hermetic” which all hybrids use, the ‘hermetic’ part being the motor runs in, and is cooled by the suction gas, which also cools the compressor cylinder head, and is actually a big loss, since this heat must be removed by the refrigeration system.

An “open” motor arrangement could have water cooled heads, and an air cooled motor, thereby reducing the load on the refrigeration system, but this ‘loss of efficiency’ is tolerated since it eliminates a shaft seal. A good mechanical shaft seal (to keep the refrigerant in) is expensive, so automotive manufacturers don’t use them, and thats why it leaks out the shaft after a few years since the seal isn’t good enough.

Specifically, hybrids and BEV’s all use 3 phase semi-hermetic air conditioning compressor units, since the motor runs in the refrigerant so no shaft seal is necessary.

Must be a slow news week.

+1 Actually now that you mention it YES all friges and home A/C units are built that way.

The only problem with this AC compressor is that I don’t see much detail on the compressor.

Maybe he hasn’t gotten that far, but as my post above shows, its not a trivial design problem.

If this dude hasn’t even considered how you seal off the refrigerant, he’s a few bottles short of a six-pack.

Or, worry about all the motor heat which if the motor is also to drive the car, the motor heat may be a considerable air conditioning load.

My Tesla Roadster eliminates this problem since the motor is air cooled.

This guy’s ‘invention’ shows absolutely NO compressor detail, just a chamber an unsealed shaft runs through, therefore, as illustrated he must work for DuPont since you’ll have to recharge the system every day since all the refrigerant will leak out. You kinda have to have a shaft on a traction motor, if only to drive a hub.

Sounds like another Great Brain.

Maybe this would be good if you were going down hill 100% of the time. But in that case you could just divert some of the regen energy to power the electric compressor. And the what happens when the ac compressor goes bad, just have to replace the whole drive motor assembly? Much more work for the technician. Kind of like the Tesla motor going bad… They have to replace the whole inverter/motor assembly because it is too hard to remove them separately.

I don’t know if that is so interesting but it sure is original. It could be valid in tropical climates.

There is another combination that could actually be better. If you use a thermoacoustic airco, you can then have a thermoacoustic generator at the same time. This means that you have airco but now also a Rex, so for a BMW i3 like car that is double gain. You get rid of the compressor for the airco by replacing it with a thermoacoustic system with no CFC or alike, and you replace the old fashion, maintenance intensive and mechanically complicate, ICE with a thermoacoustic generator.

Seems like NTU’s recent slew of EV related research news is probably intended to garner world attention to its R&D capabilities.

I work for a big tech firm and Singapore is indeed trying to move up the tech food chain from production to design. We mostly use them now for production, supply chain and minor low end design activities.

Their Economic Development Board is throwing a lot of carrots our way to boost R&D. Examples:
1) Singapore pays for half our R&D equipment.
2) Singapore pays 1st year salary for all R&D engineers we hire there.

Kudos to Singapore for trying. They realize being tiny, they cannot compete with China. However, this particular piece of “news” smells more like hot smoke than real forward progress as the more engineering astute readers here have noticed.

I would hope people don’t lose any sleep over this, since the only way they’d lose money is if they actually BOUGHT anything and that means this dude has to make it work first, which, if you read my posts above, it CAN’T. Money losing articles would be, say, if I purchased an AEROVIRONMENT round CDSC/EVSE (the standard 30 amp thingy at the Nissan Dealers) because I read the GLOWING review on PLUGINCARS.COM on ‘charging made EASY’, and there have a GUSHING review of how the Aerovironment is so heavy duty that the only thing similiarly substantial is a Clipper Creek, and lets say that put me back $1000 for the unit, and $200 to have it ‘officially installed’ on wires already hanging out of the wall, so say – $1200. And I’m thinking, this article HAS to be right because all the Nissan Dealerships use them, and Carlos Ghosn wouldn’t buy anything that is junk, and TRILLIONS of Leaf owners already have just this and they are working fine. So I go to plug in my Tesla, it won’t work, so I call Tesla and they say “OH, the AV units won’t work with Teslas (they only made Roadsters… Read more »