EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: Surrend on September 29, 2017, 08:05:08 pm
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Hi :D
I have this motor (photos enclosed) it's a NIDEC 50M3089060 - DC 24V - 1500 min^-1
It would be great if I can find a way to operate it using a 16F84A chip, I've found this assembly
http://www.elektroniksforkids.com/projects/view/PRO128/PIC-Basic-DC-Motor-Direction-Controller-using-H-Bridge.php (http://www.elektroniksforkids.com/projects/view/PRO128/PIC-Basic-DC-Motor-Direction-Controller-using-H-Bridge.php)
I would be thankful if you can provide any help.
Thanks :)
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Where did the motor/board assembly come from? Without better view of the rest of the board, it is almost impossible to tell exactly what kind of motor that is. There appear to be four terminals into the motor. There are three possibilities (perhaps more?):
1) It could be a DC brushed motor. Two of the terminals may be the motor, and the other two may be a tachometer (or something like that)?
2) It could be a bipolar stepper motor with two windings.
3) It could be a 3-phase brushless DC motor with a (fourth) common pin (Y-connected).
You need to trace the connection between the motor terminals and the other components on the PC board. For example, is that big chip a motor driver? Can you look up the part number to see what kind of chip it is?
It seems suspicious that it has a gear on the motor output shaft. It makes one think it might be a stepper motor or a gear-motor. that runs at low(er) speed?
Nidec appear to make all sorts of motors, likely including all three of the possibilities enumerated above.
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On their website they say:
Q: Where do I find a wiring diagram for my motor?
A: Online wiring diagrams are only available for current catalog products in our eCatalog. For additional ratings, you will need to send us a request for the diagram. Be sure to include the id number off of the motor nameplate.
http://www.nidec-motor.com/FAQs#{D01A22C3-4F82-4351-8320-73C8B5459F4C} (http://www.nidec-motor.com/FAQs#{D01A22C3-4F82-4351-8320-73C8B5459F4C})
Note, however, that they appear to make mostly OEM custom (bespoke) products, so don't be surprised if they can't provide anything.
But there are various ways of identifying a mystery motor.
If you have the driving circuit for the mystery motor (as you seem to have) then you are far ahead because you can see (and analyze) the circuit that was designed to drive that motor.
But even if you have a raw motor with no clues, you can use a simple and inexpensive DMM to measure between all the terminals to try to figure out what the windings are, etc. But since you appear to have the driver circuit you don't need to start from such a basic position.
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Just a wild hunch but I think that's the main (paper transport) motor from a laser printer. If so, it's brushless, constant speed, with enable. [Edit: and speed pulse output]
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Thanks for your answers gentlemen,
It's a motor I salvaged from an old laser printer, is the printer type important ?
I've tested the 4 poles of the motor (photos enclosed) and here are the results I found
I used a chinese multimeter "DT9205A" set to 200 ohm
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Seeing that skew gear, I am even more sure that it is a laser printer motor. I've seen a similar one on an HP Laserjet.
I'm assuming that the grey metal disc, with the Nidec label on it, spins with the gear? If so it is a 3-phase 'outrunner' motor. The controller is self-contained, with the driver IC underneath the U shaped heatsink. If the heatsink is easy to remove then get the IC part number and look up the datasheet.
If you can't get the chip data then the first thing to do is work out what the connector pins do. The power supply will be easy to identify - look for the two pins that connect directly to the nearest electrolytic capacitor (possibly both - at least the negative). The capacitor will show you the correct polarity.
There should be a signal to enable the rotation, hopefully logic level. Once the 24V power is connected correctly, try bridging each pin in turn via a resistor of a few kilohms, first to ground and if that doesn't work then try the same to the positive supply.
If you can get the motor to run, then there is probably a rotation sensor on the motor. Try scoping the other pins on the connector and look for a waveform. With these pins you should be able to turn the motor on and off from a micro and sense its speed/ rotor positon. I don't think you will be able to control its direction though.
If you do want to take on the challenge of controlling the motor windings directly, it looks like there are three windings with a common connection (you may be able to see three wires soldered to one of the pads - number 4?). You would connect this common connection to a positive supply and switch each winding to ground using an NPN transistor. I can see three diodes on the PCB which probably block the back emf from the windings. Your micro would need to sequence the windings in order. To work properly you would use whatever position sensors are there to syncronise the driving of the windings. There are probably (hopefully three) Hall-effect sensors.
If I were you, I would try to get the motor running with its own electronics first. Then, if you have a scope, study the winding drive waveforms and sensor signals. before you think of direct control.
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I completely agree with @Gyro. You have an ideal solution already in your hands. You have the motor and the circuit that was designed to operate the motor together there on a single circuit board. Attempting to remove the board and drive the motor yourself will be much more difficult and may well be beyond your current capabilities.
Your measurements indicate that you have a 3-phase, brushless DC motor (#3 of my possibilities). This requires a complex circuit to drive properly. But that is what is you already have there on that circuit board.
That H-bridge circuit you cited will not work with that motor. In fact you need 3x of those circuits, one for each motor winding and a complex controller driving them. But that is what is already in that circuit on your board.