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I have a stepper motor and I've noticed that when I turn the spindle with the motor lead wires touching each other, that the motor strongly resists my efforts to turn it. When the wires are not touching each other the motor turns more freely. I have inferred from this that the current that is induced from my attempts to turn it is so strong that once it is feed back into the motor, it resists the turning motion.

Now that I have connected the motor to a driver, it is my expectation that turning the spindle would not cause damaging current to be feedback into the driver to destroy it. I am concerned that turning the spindle would damage the driver because the driver's documentation states that disconnecting the motor while the system is on will damage the driver IC.

My question is: Can turning the spindle while connected to the driver cause damage to the driver?

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  • \$\begingroup\$ Controllers usually incorporate diodes to protect the FET's and provide a path for the induced currents. \$\endgroup\$ Commented Feb 21, 2011 at 0:19

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Turning the system while energized will cause high currents to flow, but disconnecting it while operating will cause high voltage as the motor's magnetic field collapses. The high voltage is probably what will damage the driver. It is designed to handle high currents.

But turning a stepper like that is generally a bad idea. From Jones on Steppers:

It is also worth noting that the best way to demagnetize something is to expose it to a high frequency-high amplitude magnetic field. Running the control system to spin the rotor at high speed when the rotor is actually stalled, or spinning the rotor at high speed against a control system trying to hold the rotor in a fixed position will both expose the rotor to a high amplitude high-frequency field.

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  • \$\begingroup\$ Thahks for the advice. I'll be sure to read that enter "Jones on Steppers" blog. \$\endgroup\$
    – user3045
    Commented Feb 21, 2011 at 0:34

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