Commutation Search
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 Commutation Search method of commutation initialization, it is possible that less axis movement will occur when you enable the axis for the first time after a controller reset than if you use the Auto-MSET method. But depending on the specifications of your motor and parameter settings, the Commutation Search method can cause more axis movement than the Auto-MSET method.
To use the
The Commutation Search 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 tries to identify the motor angle by outputting current at different electrical angles. It starts with a known electrical angle. For each angle, the drive outputs the quantity of current that is specified by the CommutationSearchCurrent Parameter for the quantity of time that is specified by the CommutationSearchTime Parameter.
- The drive initializes motor commutation based on the acceleration of the motor during the search period. The quantity of current that the drive outputs must be high enough so that loading, friction, and other opposing forces have a minimum effect on the axis. This makes sure that the search is successful.
- Motor commutation continues normally. The drive uses the feedback device specified by the FeedbackInput1 Parameter.
