Hi everyone, I need to build a prototype for my thesis and I need to control a direct drive brushless motor from a washing machine (for example, from LG) in order to regulate the speed and achieve a maximum of 150rpm. I am asking for your help because I am not very experienced in controlling motors of this type. The motor must be purchased separately (rotor and stator) and I would like to ask if you could recommend a model to use. Also, I would like to understand what type of wiring needs to be done: what type of cables come out of the motor? I have seen that there are usually Hall sensors but they are controlled by the washing machine controller, while I need to find a controller to use (what voltage? 48V?), can you recommend one? In short, as you may have understood from all these questions, I need some clarification. Thank you so much to anyone who will help me with this project!

 

Hi Mario

Welcome to AAC.

Normally when a student asks for help ("Homework help") we expect them to have at least attempted to answer their question and show their working. Asking for this level of help for a thesis is unusual, but appreciate the mechanical and electronics side might not be your primary subject area. We're going to needa lot more detail to give useful answers.

What is the subect of your thesis? And what is the motor going to drive - what are your power, torque, time to accelerate to 150rpm, etc., etc., requirements? If you don't know, you'll need to describe what the whole thing does.

 

Hi everyone, I need to build a prototype for my thesis and I need to control a direct drive brushless motor from a washing machine (for example, from LG)

Are you referring to the Fischer-Paykel, out-runner style?
That is quite the motor for experimenting.
BLDC and AC PM rotor motors are virtually identical, just the means of commutation is different.
By purchase separately , I assume you mean in one unit?
BLDC is usually the simplest drive to implement and does require sensors for commutation.
The motor connections required are 3 for the power windings and usually L.V. for the sensors.

 

Hi Irving and Max, I apologize for being brief in describing the problem. Let's say that I know for sure that it will need to be powered by 48V DC and that power is not an issue for the application I need to create. In the practical application, the motor will need to reach a lower RPM (around 100) and from what I know, for a motor of this type powered by 48V, it shouldn't be a problem (with the inverter and in its typical use in a washing machine it should reach around 1300 RPM). What I am most interested in understanding is how to control it and how to actually connect it to a controller. The type of motor is the one described by Max, and I am attaching some photos to be more precise. Thank you very much for your prompt response.

 

A BLDC motor has 2 of the 3 windings connected at any one time, look up BLDC commutation circuits.
The sensors were traditionally hall sensors, most likely what the Fischer style motor uses, Servo motor use tracks on the incremental positioning encoder to do the same thing.

 

A BLDC motor has 2 of the 3 windings connected at any one time, look up BLDC commutation circuits.
The sensors were traditionally hall sensors, most likely what the Fischer style motor uses, Servo motor use tracks on the incremental positioning encoder to do the same thing.

By doing some research, I found this driver for brushless motors. Could it work? There are the 3 wires for the various coils of the motor, and you can control the motor both with Hall sensors and without.

https://www.amazon.it/dp/B082563ZJD...&s=kitchen&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWw

 

By doing some research, I found this driver for brushless motors. Could it work? There are the 3 wires for the various coils of the motor, and you can control the motor both with Hall sensors and without.

It would seem to do the trick.

 

For what concerns the Hall sensors, is it sufficient to insert the 3 cables into the sensor located on the motor and connect them to the driver in the correct order (relative to the coils connected to the driver itself, by trial and error)?

 

You can do it with a double beam scope if you have one.
Just need to back feed (rotate) the motor to generate the 3 phases.

 

Hi everyone, I need to build a prototype for my thesis and I need to control a direct drive brushless motor from a washing machine (for example, from LG) in order to regulate the speed and achieve a maximum of 150rpm. I am asking for your help because I am not very experienced in controlling motors of this type. The motor must be purchased separately (rotor and stator) and I would like to ask if you could recommend a model to use. Also, I would like to understand what type of wiring needs to be done: what type of cables come out of the motor? I have seen that there are usually Hall sensors but they are controlled by the washing machine controller, while I need to find a controller to use (what voltage? 48V?), can you recommend one? In short, as you may have understood from all these questions, I need some clarification. Thank you so much to anyone who will help me with this project!

The motor elements are often sold as "frameless motors", with the intention that rotor and stator will be included in a separate structure that supports them both. Those motor manufacturers are often willing to provide some application support, in anticipation of their motors being used in a successful product line. You will need to be able to provide torque requirements information at the different anticipated speeds. And for any power level, higher voltages will allow a more efficient control system.

 

By doing some research, I found this driver for brushless motors. Could it work? There are the 3 wires for the various coils of the motor, and you can control the motor both with Hall sensors and without.

BTW, that drive is rated for 15a max or 12a continuous, so if you want to use as just a demonstration with the out-runner motor, it should work for no load-Demo applications, but you would need to beware it may not support high loads.

 

BTW, that drive is rated for 15a max or 12a continuous, so if you want to use as just a demonstration with the out-runner motor, it should work for no load-Demo applications, but you would need to beware it may not support high loads.

But what is the current needed by this kind of motor? I don’t find any info about its power consumption

 

Why it needs to be a washing machine motor??
Buy an electric bike motor, they have 3 phases and hall sensors built in, works with 48Volts, they come with various power levels, can handle heavy loads etc.... Then you can use sine wave drivers to control them. They are silent and operate very low RPM. Google: "KT sine wave controller" and "bike electric motor". You find tons of resources how to operate with them.
Later you can build your own electric bike........

 

But what is the current needed by this kind of motor? I don’t find any info about its power consumption

The current required by a motor depends, first, on the power it is designed to deliver. Then it also is controlled by the power that the motor is actually delivering. At the rated output torque a motor will usually draw very close to the rated supply current.
So the very first step in knowing the current is knowing the power that the motor is to supply. Then select a motor able to deliver that power.

 

Why it needs to be a washing machine motor??
Buy an electric bike motor, they have 3 phases and hall sensors built in, works with 48Volts, they come with various power levels, can handle heavy loads etc.... Then you can use sine wave drivers to control them. They are silent and operate very low RPM. Google: "KT sine wave controller" and "bike electric motor". You find tons of resources how to operate with them.
Later you can build your own electric bike........

I have seen the motors you're talking about, and I too thought it would be the simplest way to get what I want. The problem with these hub motors is that for what I need to build, I would need to rotate a fairly large disk connected to the motor, and to do that, I would need to use a drive shaft. In the case of the washing machine motor I mentioned earlier, I would make the shaft with the gear that connects to the rotor, and then this shaft would be connected to the disk with a flange. With a hub motor, it's the entire motor hub that rotates, so it's more complicated to connect it to the disk because I wouldn't know how to attach a shaft to the hub of the motor itself.

 

Here we have the first hint of the mechanical aspect of the project: " The problem with these hub motors is that for what I need to build, I would need to rotate a fairly large disk connected to the motor ." Still we have no hint as to the required torque or the overhung load or how the load would be supported. So all is guessing, which I don't choose to do based on the very limited information provided so far.
In addition to that, the claim is that this is for "A Thesis", and as such it is not clear as to how much professional assistance is allowed. Certainly there are quite a few participants here who could produce an adequate design, but that would not be honest, and also the effort would be fairly large, worth a serious financial contribution, to say the least.

 

But what is the current needed by this kind of motor? I don’t find any info about its power consumption

The current is quite low off load and if the RPM's are brought up gradually, the total current depends on the load, I suspect that these out-runner versions, take less current due to their large diameter & mechanical advantage.
They are fairly expensive to purchase new, one source maybe scrapped washing machine,, free for PU?