Curtis 1238SE - Motor Speed Constraints

3 — APPLICATION-SPECIFIC FEATURES
Curtis 1232E/34E/36E/38E & 1232SE/34SE/36SE/38SE Manual, os 31 – May 2017 Return to TOC
pg. 24
MOTOR SPEED CONSTRAINTS
e 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 rmware.
NOTE: e overall maximum motor speed* allowed is the least of the following three constraints:
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
us, for example, an 8-pole motor running synchronously at 450 Hz would rotate at 54000/8 =
6730 rpm (max). erefore the internal control soware 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)
e maximum encoder frequency the controller will accept is 10 kHz. To determine how fast this
constraint will allow your 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
e maximum motor speed the controller will allow is 8000 rpm.
Max Speed RPM Limit = 8000*
* 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 your Curtis distributor or support engineer to discuss your particular application.
Quick Links:
Max Speed Controller
Limit p.73