Resolver electrical zero position

Hi,

We are using a resolver for our axial type motor. 

Our customers requested for the following details

-position offset in degrees between the resolver's mechanical zero position and the machine's electrical zero position

- a specification of the procedure used to take the measurement.

Could you please guide me to get answers for the above questions. If there is any instrument to find the offset in degree that would also help us.

  • Hi,

    This is determined by the motor manufacturer when they attach the resolver to the motor, or by the system integrator. RDC ICs from Analog Devices, will only be able to determine the zero position as it is understood in the resolver. The rest is a mechanical alignment issue. Sometimes, if the motor has Hall effect sensors, these can be used to determine the electrical zero position, as they are always aligned with the electrical angle of the motor. Reading the resolver position at the electrical zero position (as indicated by the Hall sensors) will provide the offset value.

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  • This can be accomplished by applying a DC current into the motor phase A winding and out of the parallel B and C windings. Apply a fraction of the rated current to prevent damage to the motor. The motor will shift into alignment with the zero position, or phase A, and the reading from the resolver is the electrical zero position. In one line of your controller code, subtract off this offset and then use the result to generate the B and C references.