Motor Speed Constraints - Curtis 1239E Manual

Curtis 1239E-1269E Manual, os 37.0 RevA – May 2021

MOTOR SPEED CONSTRAINTS

The maximum motor speed is a programmable parameter in each control mode. Regardless of which
control mode is used, the maximum motor speed the controller will allow is constrained by the
number of motor poles, the encoder pulses per motor revolution, and the maximum speed constraint
imposed by the firmware. The maximum allowed speed is displayed in the Monitor » Motor » Max
Speed Controller limit variable.
NOTE: The overall maximum motor speed* allowed is the least of the following three constraints:
Quick Link:
Max Speed Controller
Limit p.80
* This maximum allowed speed is displayed in the Monitor » Motor » Max Speed Controller Limit variable
Note: In the case where the Max Speed parameter is the prevailing constraint, greater RPM may be possible.
Contact the Curtis distributor or support engineer to discuss the application.
pg. 26
1. Electrical Frequency Constraint
The controller is designed to output fundamental electrical frequencies up to 450 Hz. It
accomplishes this by clamping the Max Speed allowed, using the equation:
Max Speed Frequency Limit = 54000 / Number of Motor Poles
Thus, for example, an 8-pole motor running synchronously at 450 Hz would rotate at 54000/8 =
6730 rpm. Therefore the internal control software will limit the max speed to 6750 rpm for an
8-pole motor. Limited over-speed is allowed, for example if the motor were to go over this speed
going down a hill, the controller will still attempt to produce the correct frequency for maximized
torque and proper control; it will not simply clamp to 450 Hz.
2. Encoder Pulses/Revolution Constraint (quadrature encoder)
The maximum encoder frequency the controller will accept is 10 kHz. To determine how fast this
constraint will allow the motor to spin, use the equation:
Max Speed Encoder Limit = 600000 / Encoder Size
(e.g., a motor with a 128-pulse encoder can run up to 4687 rpm).
3. Firmware Max Speed Constraint
The maximum motor speed the controller will allow is 10,000 rpm.
Max Speed RPM Limit = 10,000*
3 — APPLICATION-SPECIFIC FEATURES
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