I would like to know how to synchronize two (nearly)-identical DC motors (approx. 1 Amp/12 VDC each) with permanent magnet, while they are driving on the same surface (railroad Track). The problem is that 2 motors of the same brand and type always have somewhat different characteristics at different speeds, resulting in (unnecessary) heating of one of the engines and its bearings. I'd like to sync them in an elect(ron)ic way as simple as possible. Thanks for help. A.

  • $\begingroup$ I am not sure what you mean by "synchronize". Are you saying you need them to run at the same speed? Could you explain what you mean by "unnecessary heating" and why you think this is happening? What are you using to power these motors? Are you running them open-loop (apply voltage and they go) or closed loop (with some kind of velocity/position feedback)? $\endgroup$ – ConjuringFrictionForces Feb 14 '17 at 20:49

Answer to: How to synchronize the motor

For a precise synchronization of the two motors (electronically), a closed loop is required:

  • The rotation is captured by a sensor
  • The sensor input a microcontroller
  • The MCU drive the motor

The typical mechanism consists of a few permanent magnets on the motor rotor, which field is detected by a hall-effect sensor.
An MCU with a Analogic-to-digital converter would sample this input at high frequency (at very least twice the maximum RPS of the motors).
The MCU drive the motors, this depends on the type of motors: for a simple DC engine, the electric circuit is pulsed (PWM) to achieve the correct speed without reducing power.

Answer to: What seem the problem

The rail contact against the wheels naturally synchronize their rotation, trying to synchronize front and rear wheels electronically would just be useless.

If any of the two motors overheat compare to the other, it is probably a malfunction of some component (motor or driver circuit). I suggest swapping the motors and see if it's the motor or the driver. In any case, replace the part if needed.
In most of the cases, a little difference is acceptable.


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