BLDC motor : 12V, 7W, 1A, 2400rpm, Torque 0.25kgf-cm, built in driver
Although this motor is three phased, it has only two wires which is + and -.
Clock wise rotation is good. But, I want this motor to be rotated in counter clock wise as well.
How can I acheive this?
Specifically, I want to control the rotation by changing the polarity of DC12V to this motor.
This motor's pictures are shown through this link. mingkimingkimingki | Flickr
If it's brushless with only 2 power wires then the 3-phase (if it's 3) are generated on-board so, unless you are handy with a soldering iron you're stuck. If it hasn't any speed or rotational feedback sensors (hall devices) and you can access at least 2 of the 3-phase cable terminations on the control board then simply reversing these two wires should do the trick. From the photos you provided it appears that such wires are readily accessible, so you may well be able to swap two of them over by adding short lengths of connecting wire to reach the new termination points
Hi jackrae
Thank you so much for your advice.
Then, for example, should I connect it like this?
Connecting one of those three phase wires to VIN?
I am sorry. I don't know which wires should be swaped.
Could you please specifically instruct me which wires should be swaped or connected?
You linked to a folder but used the img tag. So it just showed as a broken image.
If there really are only 3 wires on the board, not 6, then you should be able to just swap any two and it will run in the opposite direction.
However, it may not run as well in reverse. It depends on how they are detecting position of the rotor. If it is via current feedback on the windings, great. If it is by hall effect and the detector is set symmetrically, great.
If you have a power supply with adjustable current limit, I suggest setting it at a point that allows it to start and run normally before you modify this.
If you are wanting to flip a switch and reverse it at any time, you really should connect this up so it first cuts power. Otherwise, you may blow the driver just like connecting or disconnecting a stepper motor from a powered up driver.
Hi polymorph
Thank you very much for your valuable advice on my project.
Yes, there are only 3 wires on the board.
I should be able to control the rotation only by changing the polarity of power to this motor.
As you advised, I will swap two wires like this by soldering.
Even after this modification, if I don't get cw & ccw rotation by changing the polarity of power then please advise me what should I do next to acheive this type of control.
Because, I really need to control the rotation of this motor only by changing the power polarity.
Originally, I was using this type of DC motor(brushed).
My intention is to change this brushed motor into brushless motor.
This DC motor's rotation is changed by changing power polarity. I need to have the same control on this brushless motor.
No, no, no. This will reverse rotation with power applied in the same polarity. It will NOT make it change direction by reversing polarity of power to the motor.
I am picturing something involving a relay or two and diodes so one relay is energized at a time, depending on the incoming polarity. Connected so that when voltage is applied in one polarity, the coils are connected as they were originally and voltage to the motor circuit is positive to positive.
If the voltage is applied in the other direction, the other relay is energized, swapping those two wires, but still applying voltage to the motor circuit as positive to positive.
Kind of dicey... if power is applied to the circuit before the coils are connected, or if the coils are disconnected while power is still applied to the motor circuit, it could blow the driver IC.
Because, I really need to control the rotation of this motor only by changing the power polarity.
Then you will not be able to do that. Try finding a bidirectional ESC (electronic speed controller, as used in model cars) that is compatible with your brushless motor and you will be able to control both speed and direction of rotation.
You CANNOT reverse direction by reversing the power supply (the red and black wires on your photos). The on-board electronics will die if you try that. If you really need to have the ability to reverse direction at will then you need to bring out the two phase wires you circled in your last photo and the two solder pads they were originally connected to. Then via relays, manual switch, or whatever, you arrange for a double-pole-double-throw (DPDT) configuration of these four tails.
For some reason, to me this doesn't look like a brushless motor, but rather some kind of series or shunt (or something)-wound motor.
My argument (that it isn't brushless) is based on the following:
The first picture is of the rotor; we see two terminals where the output shaft and pinion gear are located.
Near the the front-plate in that first picture of the rotor (we can leads from those terminals as well) you can see what clearly looks like a commutator; there is also a spring (that appears for a brush - likely carbon).
I also find the rotor curiously constructed; twisted, as it is - likely to prevent or lower "cogging" effects - interesting, but not germane to my argument here.
In the second picture, we can more clearly see the terminals. I posit that these terminals are for the rotor. They would be connected up just like any other DC motor.
Pictures 3-7 show what appears to be the external field magnets; common electromagnetic arrangement. What is curious, though, are all the other surface mount parts; I am not sure what they are for at all.
Note in picture 4, the empty pads "RS" and "FR" - perhaps the extra electronics are for those pads (maybe a different model motor uses those) - though what those markings stand for, I am at a loss to guess ("Reverse" and "Forward" would be my first guess - but that's all it is - and shouldn't be relied upon).
I also notice in some of those images, the connections for the field coils seem like they are cold solder joints.
Image 8 shows a views down the field coils, where we can see one of the bearings clearly; though I am not sure why we see that here, when it is clear that in picture 1 the bearing was on the end of the motor shaft?
The remaining images show more of the same; I wouldn't mind seeing what is on the backside of the end-plate of the field coils.
This isn't a brushless motor in my opinion - again, it looks like a series-wound or shunt-wound motor; actually, since the field coils and rotor coils are seemingly powered separately, you could wire it in either configuration (and/or compound).
Take a look at this, near the end of the section, where is lists the "five types of brushed DC motor":
Note the one labelled (but not shown) named "separately excited" - I believe that is what kind of motor this motor shown is; not a brushless motor, but a form of brushed DC motor.
I don't think the first two photos relate to the rest. The OP has changed the photo shots from when he first started this thread. Perhaps he can confirm what belongs to what. Judging by the stator shape I'd surmise the motor is maybe an "out-runner" with an external magnetic rotor.
Thank you very much for your advice.
I am sorry for any confusion.
This is the images of my brushless motor.
BLDC motor : 12V, 7W, 1A, 2400rpm, Torque 0.25kgf-cm, built in driver
jackrae:
If you really need to have the ability to reverse direction at will then you need to bring out the two phase wires you circled in your last photo and the two solder pads they were originally connected to. Then via relays, manual switch, or whatever, you arrange for a double-pole-double-throw (DPDT) configuration of these four tails.
I can not use a manual switch in my application. In my application, the only control element available for motor rotation and direction is input power. This motor has to be controlled according to the variable input power.
The input power to the motor is DC12V which switches the polarity of power supply to this motor to control the direction of rotation. The original DC brushed motor's rotational direction is controlled like that.
My brushless motor should be able to cope with current input power mechanism.
polymorph:
If you are wanting to flip a switch and reverse it at any time, you really should connect this up so it first cuts power. Otherwise, you may blow the driver just like connecting or disconnecting a stepper motor from a powered up driver.
In this case, can I use some type of transistor as a switch between these two wire connection on the board?
If I do this, how can I set up a pre-power off mechanism for this connection and how can I set it up so that the motor's board could cope with the switching input power?(Polarity switching)
My requirement is, I only need cw or ccw rotation for just few seconds because my application of this motor is to open and close a small door. (Clockwise : Max 3. seconds, Counter clockwise : Max. 3 seconds) Considering this motor's rpm(2400), 3 seconds of rotation is enough for my application to open and close. But, it should be variable. Rotation is not always for 100% opening or closing.(Sometimes, a little bit opening like 50% which 1.5 seconds and closed and etc., so that the door moves like an airplane wing flaps for lift and drag according to the input power to this motor.
jackrae:
I don't think the first two photos relate to the rest. The OP has changed the photo shots from when he first started this thread. Perhaps he can confirm what belongs to what. Judging by the stator shape I'd surmise the motor is maybe an "out-runner" with an external magnetic rotor.
When I posted my answer, what are -now- the first three images weren't there! What the !@&*^$# mingki?
I now agree that the -current- first three images belong together, and the following two images are of a completely different motor (why the heck are they even in this series?!), and the remainder belong to the same motor.
Given that, my earlier diagnosis is obviously incorrect, but can one fault me given what I was presented with? Though I did have questions about all the extra electronics on what I thought was a stator winding system, and I was also confused by the seemingly extra bearing on the rotor.
mingki - let this be a lesson to you: if you want a potentially accurate solution to a problem from outside sources, you need to present your information completely and without extras that could leads others astray or confuse them.
I'll give you the benefit of the doubt here, and assume you didn't mean to confuse the issue.
That said - I don't think you can easily (or at all) reverse this motor; as jackrae has noted, it is nothing more than a similar "outrunner" style motor (though encased inside a motor can). It is very similar to a PC fan motor, in that all the timing signals and such are generated by that PCB under the stator coils, and short of modifying that PCB, you won't be able to alter directions (unless of course those two extra pads on the PCB, that I noted before, marked "RS" and "FR" - are for some kind of control signal application to change direction of the motor?).
Sorry, but CANNOT be done by simply switching the power line. A BLDC is not the same as a conventional commutator motor. You need access to the winding connections (2 out of any 3) and do the switching there.
michinyon:
It seems to me, to be an unsuitable motor for your application.
Then, could you tell me what will be the most suitable BLDC motor for my application?
I really need to pull this off. It must brushless motor and rotational direction should be controlled by switching of DC power polarity.
mingki:
can I use some type of transistor as a switch between these two wire connection on the board? Swap | mingkimingkimingki | Flickr
If I do this, how can I set up a pre-power off mechanism for this connection and how can I set it up so that the motor's board could cope with the switching input power?(Polarity switching)
My requirement is, I only need cw or ccw rotation for just few seconds because my application of this motor is to open and close a small door. (Clockwise : Max 3. seconds, Counter clockwise : Max. 3 seconds) Considering this motor's rpm(2400), 3 seconds of rotation is enough for my application to open and close. But, it should be variable. Rotation is not always for 100% opening or closing.(Sometimes, a little bit opening like 50% which 1.5 seconds and closed and etc., so that the door moves like an airplane wing flaps for lift and drag according to the input power to this motor.
mingki:
It must brushless motor and rotational direction should be controlled by switching of DC power polarity.
Hmm, you're going to have to design and build such a motor controller yourself then,
that's not how brushless motors are commutated to the best of my knowledge.
Have you worked out what those two extra connections labelled RS and FR are for ?