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Switched reluctance motors will save the planet?

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coppice:

--- Quote from: Zero999 on July 27, 2020, 10:13:49 am ---
--- Quote from: wraper on July 27, 2020, 09:00:51 am ---I can add shaded-pole induction motors with 15-30% efficiency. Consume about half of max power without any load at all. Run hot as hell. Used in almost every convection oven fan, axial AC fans and in most of 120/230V AC water pumps in washing machines and dishwashers.

--- End quote ---
That's true. I forgot, there are applications where efficiency isn't the most important design goal.

--- End quote ---
With the temperature at which some small squirrel cage motors run, fire avoidance doesn't seem to be an important design goal, either.

coppice:
The nicest thing about switched reluctance motors is how quiet they can make a lot of currently noisy home appliances. There were prototype kitchen appliances, like food mixers, with switched reluctance motors around in the 80s that were super quiet. Sadly the market preferred cheaper over quieter.

Zero999:

--- Quote from: wraper on July 27, 2020, 11:06:16 am ---
--- Quote from: Zero999 on July 27, 2020, 10:13:49 am ---That's true. I forgot, there are applications where efficiency isn't the most important design goal.

--- End quote ---
Actually it is quite important in all applications I listed, maybe besides washing machine. Motor usually runs constantly during appliance operation, so quite a lot of power is wasted.

--- End quote ---
Not really, fan oven motors only use a tiny amount of power, compared to the oven itself and the same is probably true for dishwashers. A quick Google found this one only consumes 22W. Cut that in half and we have a power saving of only 11W. The efficiency of the appliance could be improved more by better thermal insulation, than changing the motor.
https://www.espares.co.uk/product/es1548541?utm_source=google+shopping&utm_medium=shopping&utm_campaign=google+shopping&gclid=EAIaIQobChMIxYSRpqnt6gIVb4BQBh2v6w9FEAQYAiABEgLU-_D_BwE


--- Quote from: coppice on July 27, 2020, 11:23:52 am ---
--- Quote from: Zero999 on July 27, 2020, 10:13:49 am ---
--- Quote from: wraper on July 27, 2020, 09:00:51 am ---I can add shaded-pole induction motors with 15-30% efficiency. Consume about half of max power without any load at all. Run hot as hell. Used in almost every convection oven fan, axial AC fans and in most of 120/230V AC water pumps in washing machines and dishwashers.

--- End quote ---
That's true. I forgot, there are applications where efficiency isn't the most important design goal.

--- End quote ---
With the temperature at which some small squirrel cage motors run, fire avoidance doesn't seem to be an important design goal, either.

--- End quote ---
I don't think I've ever seen one catch fire. They're normally fitted with a thermal cut-out, which is usually one-shot. No doubt power could be saved by changing them for switched reluctance motors, but they tend to be the smaller, cheaper motors which only use tens of Watts, so it's not worth it. Using more copper in the windings and a copper rotor, rather than aluminium would probably give more bang for buck, than changing to switched reluctance.

Anyway, this is off-topic. The manufacturer discussed in the original post is talking about motors which use 47% of the world's electrical energy i.e. large motors. The tiny motors used in fan ovens and dishwashers are a drop in the ocean. It's total BS that half of the energy used by the world's motors is wasted.

EEVblog:

--- Quote from: wraper on July 27, 2020, 09:00:51 am ---
--- Quote from: Zero999 on July 27, 2020, 08:31:14 am ---
--- Quote ---Over 47% of the world’s electricity is consumed by analog motors. These legacy motors haven’t fundamentally evolved since the 19th century, and they waste half the energy they consume.
--- End quote ---
The only motors less than 50% efficient are those really cheap and crappy ones found in toys and cost tens of pence. :palm:

Most decent sized motors have much higher efficiencies, often above 95%.

--- End quote ---
I can add shaded-pole induction motors with 15-30% efficiency. Consume about half of max power without any load at all. Run hot as hell. Used in almost every convection oven fan, axial AC fans and in most of 120/230V AC water pumps in washing machines and dishwashers.

--- End quote ---

Probably means diddly squat in the global scheme of things though?

wraper:

--- Quote from: EEVblog on July 27, 2020, 11:09:17 pm ---Probably means diddly squat in the global scheme of things though?

--- End quote ---
Considering they are in most of homes in somewhat developed countries, IMHO it matters. Say it makes 0.1% difference in overall home electricity consumption. Globally it means energy needed for powering a few small countries.
They are also used in microwave oven fans BTW.

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