Curtis Instruments AC F4-A User Manual

3 — APPLICATION-SPECIFIC FEATURES
pg. 25
Return to TOC Curtis AC F4-A Motor Controller – August 2020
3 — APPLICATION-SPECIFIC FEATURES
Some of the controller features aect more than the electrical connections or the parameter settings.
is chapter provides background information on application-specic features, to assist the vehicle
designer in the design and vehicle-development process.
MOTOR SPEED CONSTRAINTS
e maximum motor speed (RPM) 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
Max Speed parameter.
e overall maximum motor speed* allowed is the least of the following three constraints:
1. Electrical Frequency Constraint
e controller’s (fundamental) electrical frequency goes to 500 Hz. It accomplishes this by clamping
the Max Speed allowed, using the equation:
Max Speed Frequency Limit = 60000/Number of Motor Poles
For example, an 8-pole motor running synchronously at 500 Hz can rotate to a maximum rpm
of 60000/8 = 7500 rpm (max). In this case, the control soware will limit the max speed to 7500
rpm for an 8-pole motor. ere is a limited over-speed, should the motor exceed this speed (e.g.,
going down a hill). e controller will still attempt to produce the correct frequency for maximized
torque and proper control; it will not simply clamp to 500 Hz.
2. Encoder Pulses/Revolution Constraint (quadrature encoder)
e maximum encoder frequency the controller will accept is 30 kHz. To determine how fast this
constraint will allow the motor to spin, use the equation:
Max Speed Encoder Limit = 1800000/Encoder Steps
Due to the high encoder frequency ability, encoders with lower pulses per revolution (ppr) will not
be the limiting factor in motor rpm (e.g., a motor with a 128-pulse encoder can run up to 14,062
rpm, which is greater than the rmware limit, yet a 256-pulse encoder will be limited to 7,031 rpm).
3. Max Speed Parameter Constraint
e maximum motor speed the controller will allow is 8000 rpm.
Max Speed RPM Limit = 8000*
*The variable, Max Speed Controller Limit (0x30AF 0x00) displays this maximum limit. See the AC Motor Setup parameter
menu.
Note: In the case where the Max Speed parameter is the prevailing constraint, greater RPM is possible. Contact the Curtis
distributor or support engineer to discuss the particular application.

Curtis Instruments AC F4-A Specifications

General

Brand	Curtis Instruments
Model	AC F4-A
Category	Controller
Language	English