US Ceiling Fan Efficiency Rule Proposal

[wraper]

I can't say I've ever noticed any whine from a BLDC motor, even when I was much younger and could hear over 20kHz.

Nevertheless, it is a well known phenomenon.  Microchip even made an appnote (AN771: Suppressing Acoustic Noise in PWM Fan Speed Control Systems) about it in 2002.  Feel free to ignore me (many do, and that's okay), but please do read that appnote to understand the issue I'm trying to bring up.  It affects slow high-current/high-load (large fan assembly) fans in particular, so therefore definitely does apply to BLDC ceiling fan motors also (or rather, their control circuitry, which is basically the only part manufacturers can cost-cut anymore, with just about everything else being basically standard).

Idiot engineer phenomenon. Appnote about of how to make ridiculous garbage a little bit less of garbage. You cannot safely PWM power of 99% of brusheless fans to begin with. Brusheless fan speed must be controlled through its PWM wire (if present) or by adjusting DC voltage, not PWMing it's power. Yet some engineers think it's fine despite fans generally having an electrolytic capacitor across their power and driver IC which are not supposed to be abused this way. Heck, Sunon even explicitly forbids it in their datasheets, I guess because there are enough idiots who think otherwise.

[Nominal Animal]

I can't say I've ever noticed any whine from a BLDC motor, even when I was much younger and could hear over 20kHz.

Nevertheless, it is a well known phenomenon.  Microchip even made an appnote (AN771: Suppressing Acoustic Noise in PWM Fan Speed Control Systems) about it in 2002.  Feel free to ignore me (many do, and that's okay), but please do read that appnote to understand the issue I'm trying to bring up.  It affects slow high-current/high-load (large fan assembly) fans in particular, so therefore definitely does apply to BLDC ceiling fan motors also (or rather, their control circuitry, which is basically the only part manufacturers can cost-cut anymore, with just about everything else being basically standard).

Idiot engineer phenomenon. Appnote about of how to make ridiculous garbage a little bit less of garbage. You cannot safely PWM power of 99% of brusheless fans to begin with. Brusheless fan speed must be controlled through its PWM wire (if present) or by adjusting DC voltage, not PWMing it's power. Yet some engineers think it's fine despite fans generally having an electrolytic capacitor across their power and driver IC which are not supposed to be abused this way. Heck, Sunnon even explicitly forbids it in their datasheets, I guess because there are enough idiots who think otherwise.

Agreed; and those engineers get paid to do that only because it is cheaper than doing it properly.

On the PC fan side, those motor designs got kicked in the teeth as users basically rejected them, and even the cheapest mass producers have shifted to more sensible driving schemes.

Ten to twenty years ago, there were only very minor differences between fan blade designs, with quiet fans just having blade geometry well matched to their motor.  Nexus was the bees knees back then for general use.  Gentle Typhoon had optimal geometry for intake fans, as they could deal with filters' airflow impedance without becoming noisy.  3-pin (voltage controlled, no PWM) fans were quieter and with nicer noise spectrum than 4-pin PWM-controlled fans, as you can find out yourself by looking at fan noise comparisons back then (by SPCR for example).  Noctua started with good CPU heatsink designs, with well matched fans; and then went on to optimize their fans for low noise and good airflow by both working on the motor designs (their sinusoidal BLDC drive ICs, bearing designs) and later even on the blade geometry.  Now several manufacturers design their own blade geometries with both noise and airflow in mind.

Since this already happened with PC fans, taking a decade from the arrival of PWM-controlled fans to actually good motor and blade designs to be available, I'm just afraid something similar will happen with ceiling fans.  The current ceiling fan AC motors may not be as efficient as possible, but they for sure are reliable and quiet; the two things that matter to me personally more than the exact power usage.  To me, it would be a HUGE step backwards to replace a perfectly good, reliable, quiet ceiling fan with one that has a one-year warranty, a high-pitch squeal I can hear when trying to sleep in the summer, much higher price (due to the more complex construction and electronics), but with lower energy consumption.

Sure, I could be wrong.  But when something similar has already happened in the past, history tells us things tend to repeat the same way.

[bdunham7]

Instead, we should demand reliable electronics, because the 99% of cases show that this is entirely possible.

In fact, to the extent that the government causes the issue by mandating levels of efficiency that sometimes results in less reliable products, they should mitigate the problem by requiring very long warranty periods.  After all, if their goal is to save energy and the environment, surely long-lived appliances results in less manufacturing (consumption of energy and raw materials) and less waste.  Recycling is a poor substitute for long product life.

By long warranty periods I mean refrigerators/dehumidifiers/AC units - 20 years, clothes washers/dryers/dishwashers - 10 years.  Ceiling fans - 50 years. 

[wraper]

Agreed; and those engineers get paid to do that only because it is cheaper than doing it properly.

And then you have failing fans, whiny noise and rattling sound during fan start. The problem is that I've seen this not only in cheapest devices but where such economy makes not economical sense. I'm pretty sure it's more of incompetency rather than saving $0.05 BOM cost.

[wraper]

To me, it would be a HUGE step backwards to replace a perfectly good, reliable, quiet ceiling fan with one that has a one-year warranty, a high-pitch squeal I can hear when trying to sleep in the summer, much higher price (due to the more complex construction and electronics), but with lower energy consumption.

Sure, I could be wrong.  But when something similar has already happened in the past, history tells us things tend to repeat the same way.

BLDC is more reliable in general because there is no run capacitor that degrades and they do not heat nearly as much due to high efficiency. Shaded pole motor that is most common in AC fans on other hand is cheap but super inefficient, heats like hell and that heat kills bearings. Not surprising due to ~25% efficiency.

[RJSV]

Thanks PwrElectronics:
   First of all, nothing personal, I'm a very criticism filled EE.

   (We gonna learn and hear about a myriad of Engineering issues, from the mouths of the barely educated.  Now, if you think I'm out of line, bringing in the racial diversity dynamics, try figuring out who (may) be pushing for a DC fan style, (ignorant of engineering issues brought up here).  Odds are, that person came out of school with a degree in 'Multi-ethnic Studies', and would reply with:
  "AC, DC, smeecy"....you WILL comply.

   Were you surprised, when that 'Gas Oven ban' wasn't a one-off thing?  A glitch, never to happen again ?

   In a real situation, (climate change disasters) we are going to need ENGINEERS doing the science.  The whole 'diversity thing likely will get plugged in, with any large technology change (shoved down our throats).

thanks, there.
- - Rick

[RJSV]

Yes, A DISMISSAL, quite a tired taktic being used these days, to avoid any substantive debate.
   It's, 'too ridiculous' to even touch....next you should maybe say: (and again, a tired, dismissive phrase), SAY:
   "You people seem to see a conspiracy behind every tree..."
   
   But that would be baiting, after you stepped in the poo.
   Sometimes you've got to wait, for the consequences to manifest.

   What other 'delusion' accusing talking points do you have, because (we) can't just sit here calling each other a 'Ninny',
No, you're a ninny...back and forth.   Why don't you, uh, hit us critical thinkers with some good attacks, rather than repeating same old dismissals.

   Do you have a gas stove ?  Try some effective 'gas lighting' so we can respect your dismissals as being valid.

Rejected yours.

[gnuarm]

Now, if you think I'm out of line, bringing in the racial diversity dynamics, try figuring out who (may) be pushing for a DC fan style, (ignorant of engineering issues brought up here).

Yes, I think that is way out of line and quite ridiculous.

I was going to say there's no way to show you don't consider a post appropriate to the forum... but there is a link to report the post to the moderator, which I have done.  I hope others do as well.

[Siwastaja]

BLDC is more reliable in general because there is no run capacitor that degrades and they do not heat nearly as much due to high efficiency. Shaded pole motor that is most common in AC fans on other hand is cheap but super inefficient, heats like hell and that heat kills bearings. Not surprising due to ~25% efficiency.

This matches with my experience. "Good old" cheap inefficient AC motors have failure modes such as destruction of run capacitor or destruction of bearings (oil) due to too high operating temperature. BLDC fan has all the chances to be much more reliable. Those that fail fast are outliers; I also strongly agree with bdunham7 that if and when governments apply laws mandating better efficiency, they should be coupled with better lifetime requirements, too.

[Nominal Animal]

if and when governments apply laws mandating better efficiency, they should be coupled with better lifetime requirements, too.

True; that should ensure the quality.

Yet... When was the last time you remember lifetime requirements being extended?

Here in Finland, the climate is quite challenging for house builders, swinging from an occasional -40°C in coldest winters to +30°C during hottest summers.
Yet, the typical warranty period is only 5 years, and most houses are designed for only a 30 - 50 year lifetime.
Now that EU will require much, much higher energy efficiency for houses, they have not and will not address the warranty period or manufacturer/builder responsibility at all.  Funny thing is, you could achieve the energy efficiencies easily, simply by making thicker walls.  Apartment buildings built 100-150 years ago in Helsinki still fulfill even the strictest energy efficiency requirements, simply because they have walls half a meter thick of stone and concrete.  That will not happen, because new is always better and "we can achieve the same energy efficiency with these layered plastic and insulator structures" (which will be first-rate grow zones for mold as the sharp temperature differences will cause water to condensate there, and there is no mechanism to dry it out).  The apartment I'm renting right now, for example, has such an outer wall structure that if you were to screw anything into the outer wall, you'd compromise the vapourtight barriers and the outer wall, and possibly compromise the long-term stability of that outer wall altogether.  This is relatively common in new buildings, too.

Thus, while longer lifetime requirement would obviously make the primary worries go away, I do not see such requirements happening at all.

[SiliconWizard]

Thus, while longer lifetime requirement would obviously make the primary worries go away, I do not see such requirements happening at all.

I don't either. And actually, if you set no lifetime requirement, efficiency requirements are possibly going to lead to shorter lifetimes in practice.