Automatic Motor Set (Auto-MSET)
You can use the
The Auto-MSET method typically has more accurate and repeatable commutation than the Commutation Search method. When you use the Auto-MSET method, the motor typically moves less than 0.5 electrical cycles. But, it can move a maximum of 1.5 electrical cycles. When you use the Commutation Search method, it is possible that much less axis movement occurs, but this is not always how it works. Depending on the specifications of your motor and your parameter settings, the Commutation Search method can have greater axis movement than the Auto-MSET method.
For AC brushless motors that do not have Hall-effect switches, Aerotech recommends that you use the Auto-MSET method of commutation initialization unless your process cannot tolerate the motor moving a maximum of 1.5 electrical cycles when you enable the axis for the first time after a controller reset.
You can use the CommutationInitializationAngle Parameter to make sure that your motor commutation behaves identically after the first time that you home the axis after every controller reset. To learn how to use this parameter to compensate for the variability in commutation initialization that occurs with the Auto-MSET and Commutation Search methods, refer to the CommutationInitializationAngle Parameter.
IMPORTANT: When you use the Automatic Motor Set (Auto-MSET) method of commutation initialization, the motor typically moves less than 0.5 electrical cycles when you enable the axis for the first time after a controller reset. But, it can move a maximum of 1.5 electrical cycles.
To use the
The Automatic Motor Set (Auto-MSET) Method:
- The process starts when you enable the axis for the first time after a controller reset. You can enable axes in the Axis Dashboard Module or use the
Enable()function. - The drive outputs current to the motor at a known, fixed, electrical angle that you specify for the AutoMsetAngle Parameter. During the time that is specified in the AutoMsetRampTime Parameter, the current ramps up from zero to the specified value of the AutoMsetCurrent Parameter.
- Some conditions can cause Auto-MSET to automatically restart and specify a new electrical angle. If this occurs, it can cause the motor to initialize to an electrical angle that is different from the AutoMsetAngle Parameter.
These conditions are as follows:
- No motion is detected on the axis.
- Motion is detected into a limit.
- The drive holds the level of current specified by the AutoMsetCurrent parameter for the quantity of time specified by the AutoMsetTime Parameter. This makes sure that the motor moves to the specified angle. The level of current that the drive holds must be high enough so that loading, friction, and other opposing forces have a minimum effect on the motor angle.
- If the drive does not detect enough motion on the axis after it tries many different electrical angles, it will give a CommutationFault. If a CommutationFault does not occur, the drive initializes motor commutation by assuming that the motor is now at the angle specified by the AutoMsetAngle parameter. Then motor commutation continues normally. The drive uses the feedback device specified by the FeedbackInput1 Parameter.
