Brushless Motor ( ESC BLDC) Controller

Thread Starter

I like to build

Joined Mar 1, 2022
4
I wish to find information on motor controllers for Brushless Direct Current (BLDC) motors. There was a discussion thread on this forum, “Find or Make a Motor Controller for the Fisher & Paykel Washing Machine Smart Drive Motor”, which was started in June 2019. A number of responses in that thread contain helpful information, but none seem to have provided a definitive answer.

The motor I would like to repurpose is from a Fisher and Paykel Aquasmart washing machine model WL80T65CW1, using 240 volt AC single phase power. I would particularly like to use it as a variable speed motor (rather than fixed speed), to operate a honey extractor which operates a bit like the spin dryer of a washing machine, but at a much lower speed.

There seems to be an abundance of information about BLDC motors, which explains the general principles of how they work, and I am thankful to those contributors who gave information in that discussion thread.

Likewise there seem to be many different ESC BLDC motor controllers available for very small motors, or very low power motors, and which are powered by batteries, or by low voltages. I have not found anything yet which is clearly identified as suitable for a more powerful motor such as a washing machine motor, and powered by 240 volt mains electric power.

I have found some circuit diagrams for BLDC motor controllers, but these seem to be designed for lower power / lower voltage applications – and also for fixed speed rather than variable speed. Does anyone have information which may be helpful in modifying such a circuit, to accommodate higher voltage and higher power?

It is obvious that the motor control unit from a washing machine is capable of operating the motor, but that controller has a lot of functional capability that does not apply for a honey extractor (for example water level sensing in a washing machine).

I have a motor control module (from the washing machine), which has an intermittent fault in one of its sensing circuits (the lid-lock mechanism), but it is still capable of running the motor. If it is possible to somehow inactivate those circuits which are separate from just running the motor, then I would regard this as a very helpful option.

Other than that, I hope that it may be possible to obtain a general-purpose variable-speed controller which can enable the motor to deliver its full power capability from 240 volt AC input power.
 

MisterBill2

Joined Jan 23, 2018
11,900
One option is to trace out the circuit of the motor control module that you have, starting from the motor drive circuit and going back toward the control circuits. At some point it will become apparent where the interlocks come in, and at that point they can be bypassed.
OR, tracing the portion with the intermittent fault should reveal the path needing to be bypassed.
 

KeithWalker

Joined Jul 10, 2017
2,354
You will not be able to use the washing machine control circuit as a variable speed control. It contains a pre-determined program that can only be varied by the control settings and interlocks in the washing machine. Any combination of those inputs will not give variable speed control.
 

Ya’akov

Joined Jan 27, 2019
5,666
You will not be able to use the washing machine control circuit as a variable speed control. It contains a pre-determined program that can only be varied by the control settings and interlocks in the washing machine. Any combination of those inputs will not give variable speed control.
The F&P machines vary the speed dynamically so somewhere there is a PWM signal being used to determine the speed. Even if the MCU is generating it, it’s very possible it is not directly driving the motor, so there may be an opportunity to take over the operation of an ESC circuit on the board.
 

KeithWalker

Joined Jul 10, 2017
2,354
The F&P machines vary the speed dynamically so somewhere there is a PWM signal being used to determine the speed. Even if the MCU is generating it, it’s very possible it is not directly driving the motor, so there may be an opportunity to take over the operation of an ESC circuit on the board.
Then how do you plan on finding out what inputs determine the speed of the motor? It sounds rather like a closed loop feedback system.
 

Ya’akov

Joined Jan 27, 2019
5,666
Then how do you plan on finding out what inputs determine the speed of the motor? It sounds rather like a closed loop feedback system.
My idea, which is only a possibility, is to check the board to see if the speed control circuitry is sufficiently independent to hijack it. It doesn't depend on the existing MCU at all, The question is whether the speed control is done by the MCU directly controlling the MOSFETs or by a separate circuit, to which the MCU provides a PWM signal.

I do know the motor is MOSFET driven and that there is a rotation sensor involved. Looking at the board is the only way to know if what I am thinking might be possible is possible.
 

Thread Starter

I like to build

Joined Mar 1, 2022
4
I appreciate very much that the comments made so far are trying to offer helpful advice. It would seem that I am not the only one who would like to be able to utilize a BLDC motor which has been salvaged from a washing machine. These motors seem to be attractive for a number of reasons: they are efficient in operation, can operate from low speed to high speed, can operate in forward or reverse rotation, and more. The problem for hobbyists like me is that they require controllers which have a different level of sophistication.

I think that it would be wonderful – even exciting – if the controller from a washing machine could easily be adapted for hobbyist use. I have looked closely at the printed circuitry, and complex component layout, including the microprocessor, on the washing machine controller, and recognise immediately that I do not have the skill or knowledge to analyse or perform any type of reverse engineering. Perhaps it is something of a forlorn hope to ask any of the members of this forum to undertake such a research project just for me. Never-the-less I would be extremely grateful to receive advice from someone who has actually undertaken such a project.

In reality, I hope that advice could be given about the use of some existing BLDC general purpose controller. For example, I have seen various controllers advertised on ebay for electric bikes, such as “36V/48V 350W Brushless DC Motor Speed Controller For Electric Scooter E-Bike”.

I have not been able to check the actual voltage supplied by the washing machine controller to the washing machine BLDC motor. The washing machine operates on 240 volt AC single phase power and it would seem that the motor actually runs at this kind of voltage (DC), as it seems to have a rectifier, but no transformer to reduce the voltage. Does anyone know how this motor might perform if it was powered by means of an E-Bike controller?
 

MisterBill2

Joined Jan 23, 2018
11,900
Switching power supplies cost much less than transformers and so you will seldom find large transformers any more. Try searching for the motor part number instead.
 

Ya’akov

Joined Jan 27, 2019
5,666
The DC in BLDC motor can lead you to believe the motor speed is controlled by sending vary voltages of DC, like you might for a brushed motor. The brushless part is much more important to understanding how the motor operates.

A BLDC motor is also called an EC (Electronically Commutated) motor. It has much more in common with a 3-phase AC motor than with a brushed DC motor. The motor controller sends DC to one of three coils in the motor depending on it’s position which is sensed by something like hall effect sensors which can detect magnetic fields, or by a rotary encoder that mechanically track the position by rotating with it. By using the position information the controller can do what the brushed motor’s commutator does but electronically rather than mechanically, deliver current to the winding in a position to move the motor’s rotor along.

See this post here for one scheme powering an F&P motor, and the thread it is in for more information. Unfortunately, it appears you are not in for an easy time whatever you do.
 

MaxHeadRoom

Joined Jul 18, 2013
25,214
A BLDC motor is also called an EC (Electronically Commutated) motor. It has much more in common with a 3-phase AC motor than with a brushed DC motor.
The BLDC is named as it simulates a DC brushed motor, turned inside-out, as only two of the three stator windings are powered at any one time.
The 3ph PM motor is identical in construction, but typically the windings are 3 phase fed.
I have converted the 3phase CNC Fanuc style to BLDC by fitting a 3pulse commutating encoder.
If you back feed (rotate) them, they both generate a 3phase waveform.
 

shortbus

Joined Sep 30, 2009
9,375
Yes, it seems that driving F&P motors is widely desired but rarely done well.
That partly is because many doing it want to run them on battery power, instead of mains. That means they have to have the stator coils reconfigured, not rewound just changed from series to parallel connections.

since it seems the F&P motors use Hall sensors for the commutation method, it maybe easier to skip a micro controller altogether, and go old school. Use the original IC to do it, the MC33035. That was in the beginning of BLDC motors what was used. They have even come up with a break out board now that makes using one easier - https://www.electronics-lab.com/project/mc33035-brushless-motor-driver-breakout-board/
 

MisterBill2

Joined Jan 23, 2018
11,900
I think that I have seen schemes for operation that involve more than a singe winding being excited at any given time. Certainly emulating the regular 3-phase drive scheme should be able to work, and provide more torque and smoother operation. also it should be possible to run the motor open loop, without position feedback. Synchronous motors do it, I know.
 

MaxHeadRoom

Joined Jul 18, 2013
25,214
. Certainly emulating the regular 3-phase drive scheme should be able to work, and provide more torque and smoother operation.
Typically BLDC motors have proved to be higher torque than 3ph versions for a given motor size.
The problem seen with both however, is cogging at low rpm's unless PID feedback is implemented.
 

MisterBill2

Joined Jan 23, 2018
11,900
Typically BLDC motors have proved to be higher torque than 3ph versions for a given motor size.
The problem seen with both however, is cogging at low rpm's unless PID feedback is implemented.
Low speed cogging has always been an issue with stepper motors as well, especially at low speeds. Muti-winding excitation has provided a bit of reduction in some instances but the complication is significant. For a lathe application the solution is a heavy flywheel. and an elastic drive belt.
 
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MisterBill2

Joined Jan 23, 2018
11,900
One more possible choice would be to use one of the variable-speed drives intended to run a 3-phase motor from single phase mains. As the motor is certainly less than one HP the drive should be reasonable. Check Automation Direct for the best price. Those drives can be set up for a variety of motor types and ratings. I am likely to be challenged by somebody who thinks the brushless DC motors actually run with DC in the coils. The brushless part of the name means that the commutation is done by electronics instead of brushes.
 
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shortbus

Joined Sep 30, 2009
9,375
One more possible choice would be to use one of the variable-speed drives intended to run a 3-phase motor from single phase mains.
Yet again. You do know that the letters "BLDC" stand for brush less DC don't you? So if you do how will one work with a VFD made for 3PH motors, that out puts AC? Explain that to me.
 

nsaspook

Joined Aug 27, 2009
9,740
Yet again. You do know that the letters "BLDC" stand for brush less DC don't you? So if you do how will one work with a VFD made for 3PH motors, that out puts AC? Explain that to me.
It might seem strange but BLDC and your 'normal' brushed DC motors are actually AC (not necessarily sinusoidal) at the coils during the spin cycle. The difference is where the commutation happens, at mechanical shaft brushes or at a external controller using electronic switches.
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https://www.monolithicpower.com/en/brushless-vs-brushed-dc-motors#:~:text=There are two types of,commutation function with electronic control.

Yes, BLDC motors are driven with a 3PH AC motor controller with PM magnetic field considerations for not being an induction motor
 
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