Just a comment for people running out to get free motors, every appliance motor (larger than a drill or wood router) I've seen here in the USA for a very long time has been a brushless motor of some type. Mostly simple induction motors with a run and maybe start capacitor. More recent ones may be 3 phase with a VFD controller like in my LG washing machine above. Here's a random example of a modern USA washing machine motor.
https://www.amazon.com/Frigidaire-13.../dp/B00M25OKO8
Attachment 29960
Pancake motor. F&P smartdrive motor. Invented in NZ 20 odd years ago for an electric lawnmower and now made under license and used in all sorts of things. A lot get used as generators for wind and water but have been used with an inverter and VFD for Paraplanes and rewired six ways to Sunday for all sorts of projects.
Not a full history but one mans take: https://www.youtube.com/watch?v=KLzHr0Qntgo
Great description you found NortonDommi. Those large diameters would clearly generate better than smaller. Most of the home-size wind units are barely alternator size; the real ground-breaker seems being the Honeywell, essentially magnets carried at tips of propeller, many many additional segments. A stack of smart drive pancake units would be serious potential indeed.
To you and jdurand alike, what is the attraction or features of washer motors sought in powering small machines? Treadmills are obvious being compact and variable by DC. I'd surmise washers to be single speed, varied by transmissions or sheave; is that not the case? Clue I haven't unraveled is the extensive wire harness, apparently more than just timing of cycles.
I think it's like computer power supplies, people see them and figure it's something like I need so I'll just use it. Sometimes it's a reasonable fit, sometimes not. When it's not I've seen people go through a lot of trouble to make it fit.Quote:
Originally Posted by Toolmaker51
Here in the US I haven't seen brushed motors on anything bigger than a circular saw, drill, or vacuum cleaner. Washing machines, refrigerators, pumps all have induction motors of some sort on them. So, if the motor is the speed you can use and you have the right circuit to drive it (probably just capacitors but may need a start timer), go for it.
Are brush type motors common in 220V/50Hz land? I could see where they might, induction motors start getting big on 50Hz.
example of getting carried away using the wrong thing:
One of the 3D printers our company had was a big delta printer, what did it use? A PC power supply. The company that made these printers had all sorts of issues (PC power supplies are quasi-regulated, they generally only work right if there's a heavy load on the 5V output). They kept going to better and more expensive PC power supplies. When we got one of the printers I tossed the PC power supply before plugging it in and replaced it with a cheap, industrial 12V power supply. Not the slightest problem from that and I could buy 3 of those industrial supplies for one quality PC power supply. Smaller, too.
If you can grab an induction motor great! As you guess, in 240v land, or at least here in the UK, the brushed universal motors are very popular in washing machines. They are NOT the perfect choice for machine tools like a small lathe, as they generate max torque at about 8,000 RPM... For the sake of a quiet life most that do use them, will tend to limit this to about 4k RPM, and use pulley reduction as well. They are still powerful enough for a 13mm chuck pillar drill or smallish lathe at that speed.Quote:
Originally Posted by jdurand
On the plus side, and the biggest reason for using such a motor in the shop is that it is a ready 3/4 HP motor that you already have laying about, or can source it for free - easy in the UK at least! Electronic speed control is a must, to limit no-load speed. Hence the video on simple speed control circuits machine.construction/motor_control.
DC Treadmill motors are great, especially if you can get the controller working too - but these motors are much harder to salvage for free. I nabbed one once when a local gym were clearing out, but every other time I have tried people have asked for quite a bit of monies, even for used ones.
I have a name brand blender that controls the series-wound motor with a low budget controller. A sensor counts the fan blades going by and gates a TRIAC on/off for the motor. Doesn't appear to have any attempt at PWM, just bang-bang.
A food mixer by the same company also uses simple triac gating. They have a centrifugal weight arrangement like used for the start winding on a motor. Only by sliding a lever on the side of the motor spring tension on the centrifugal weight is adjusted, changing the RPM for the cut-out.
For VERY smooth control of series-wound motors you actually ignore zero crossing entirely. You put a bridge rectifier (AC terminals) in series with the motor. Across the DC terminals you put an appropriately sized MOSFET. Now, simply put a 100kHz PWM wave onto the MOSFET gate with an opto-isolator and you have smooth power control. Add a tachometer to that and you now have full speed control. Add current control and now you have safe trip on overload.
I was maintaining industrial production equipment back in the 1980s and I remember the rotary tables that positioned parts under a laser used flat motors. Very good at fast starts/stops with low RPM. Not so good when you're testing a live motor and the pointy haired boss sneaks up behind us and yells "IS IT WORKING YET!" The cloud of smoke that came out of the motor would have been comical if we didn't now have to fix that in addition to the original adjustment.Quote:
Originally Posted by NortonDommi
Our Samsung washer has the same type of motor. I’ve watched it turn the drum slowly backwards after adding clothes. I believe it does this to ‘weigh’ the load so that more water can be added if necessary.
Our Samsung washer has the same type of motor. I’ve watched it turn the drum slowly backwards after adding clothes. I believe it does this to ‘weigh’ the load so that more water can be added if necessary.
The link is dead.
