Circuits to reuse washing machine motors to drive workshop tools

[Bongodrummer]

The 3/4 horse power universal motors used in washing machines are an abundant source of power for all kinds of workshop tools, from a small lathe to a disc sander The problem is we can't just hook them up to their rated voltage without some kind of control circuit. At no-load speeds the motor goes so fast it damages itself.

In the past I have used a few different control circuits to control these motors. The most recent is used in the multi purpose rotary tool I have been making http://machine.construction/rotary_tool In this I use a closed loop Arduino based circuit that uses a PID algorithm to try and match your desired set speed, with the actual measured rpm of the washing machine motor. This was a relatively complicated circuit, and in the video I show how to make it and compare it to the more simple triac based circuits.

[jdurand]

My washing machine (LG brand) has a multi-phase motor with the armature bolted right to the drum (no belts or gears). I think it's driven as a stepper from the sound and the low speed torque.

Be an interesting motor to salvage for things like rotary tables. I wonder if the drive electronics are separable from the processor?

[Bongodrummer]

My washing machine (LG brand) has a multi-phase motor with the armature bolted right to the drum (no belts or gears). I think it's driven as a stepper from the sound and the low speed torque.

Be an interesting motor to salvage for things like rotary tables. I wonder if the drive electronics are separable from the processor?

That is really interesting. Sounds like it would make a reasonable motor for some kind of CNC application if you could untangle it from the drum, and get a handle on the control board?

[jdurand]

At the moment it's doing our laundry, so I may have to wait a while for spousal approval of an autopsy.

[DIYer]

Thanks bongodrummer! We've added your Electric Motor Control Circuit to our Electronics category,
as well as to your builder page: bongodrummer's Homemade Tools. Your receipt:

Electric Motor Control Circuit by bongodrummer

tags: motor, controller

[Toolmaker51]

At the moment it's doing our laundry, so I may have to wait a while for spousal approval of an autopsy.

Yep. A motordectomy is sure to be noticed.

[jdurand]

I found a picture of the motor from a repair parts place


link to the repair place
https://www.huoltopalvelu.com/LG-was...ct-drive-motor

[jdurand]

Looks like it's only 3 phase so they're using a VFD to drive it.

[Christophe Mineau]

Hi, thanks a lot for that very clear video, this is really valuable stuff, and I think you are one of the first across the World Wide Web to fully document and explain the close loop circuit.
Driving a washing machine motor is one of the most massive technical meme and one could read hundreds of forum pages dealing with this question, (and I have read many of them).
There are only a few solutions that can be workable with universal motors, and most of the time, the proposed solutions keep open loop and cannot offer a proper regulated speed control. For closed loop solution, the principle is often explained, but no practical solution is ever showed, except this guy, you probably visited his page, who makes home brewery, and started an equivalent project, but I don't think his page is as well documented and explained as yours.
Just to mention that there is also an alternative using a tda1085 circuit, there is a Russian guy selling the PCB on eBay, even a wired version, but it's not as easy and maybe there is a parametering issue as you mentioned at the end.

So , congratulations and many thanks for this so valuable post ! And keep posting!
Cheers,
Christophe

[Bongodrummer]

Hi Christophe. I really appreciate the encouragement, thanks!
As you say it is quite the technical challenge to do closed loop control on a universal motor, and I think it's just on the limit of what the Arduino is capable of...