AMCI SD4840EK, Руководство пользователя

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20 Gear Drive, Plymouth Ind. Park, Terryville, CT 06786
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Tel: (860) 585-1254 Fax: (860) 584-1973 http://www.amci.com
SD4840EK User Manual
I
NTRODUCTION TO THE
SD4840EK
15
Driver Functionality
This table summarizes the features of the stepper motor driver portion of the SD4840EK.
Table R1.3 Driver Functionality
Idle Current Reduction
Idle Current Reduction allows you to prolong the life of your motor by reducing its idling temperature. Values
for this parameter range from 0% (no holding torque when idle) to 100%.
Idle current reduction should be used whenever possible. By reducing the current, you are reducing the I
2
R
losses in the motor. Therefore, the temperature drop in the motor is exponential, not linear. This means that
even a small reduction in the idle current can have a large effect on the temperature of the motor.
Note that the reduction values are “to” values, not “by” values. Setting a motor current to
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4 Arms and the current reduction to 25% will result in an idle current of 1Apk. (The
SD4840EK always switch from RMS to peak current control when the motor is idle.)
Current Loop Gain
This feature gives you the ability to adjust the gain of the power amplifiers in the SD4840EK to match the
electrical characteristics of your motor. The value of this parameter can range from 1 to 80 with 80 represent-
ing the largest gain increase. In general, using a larger gain will increase high speed torque but the motor will
run louder. A lower gain will offer quieter low speed operation at the cost of some high speed torque.
The use of this feature is completely optional and you can leave the Current Loop Gain at its default setting of
“1” for standard motor performance.
For AMCI motors, use a value of “5” as a starting point.
High induction motors, often referred to as “tin can” steppers, need a higher Current Loop
Gain setting for normal operation. For these motors, start with a Current Loop Gain of “20”.
Feature Benefits
RMS Current Control
RMS current control give the SD4840EK the ability to drive the motor at its
fully rated power when microstepping. Peak current controllers typically
experience a 30% drop in power when microstepping a motor.
Programmable
Motor Current
RMS current supplied to the motor can be programmed from 0.1 to 4.0 amps
in 0.1 amp increments. This allows you to use the driver with the full line of
AMCI stepper motors.
Programmable Idle
Current Reduction
Extends motor life by reducing the motor current when not running. This
extends the life of the motor by reducing its operating temperature.
Programmable
Current Loop Gain
Allows you to tailor the driver circuitry to the motor’s impedance, thereby
maximizing your motor’s performance.
Programmable
Motor Steps/Turn
Allows you to scale your motor count to a real world value. (counts per inch,
counts per degree, etc.)
Anti-Resonance Circuitry
This circuitry gives the SD4840EK the ability to modify motor current
waveforms to compensate for mechanical resonance in your system. This
will give you smooth performance over the entire speed range of the motor.
Wiring Short Detection
Safety feature that removes power from the motor if a short is detected in
one of its windings.
Over Temperature
Detection
The SD4840EK sets a warning bit in the network data when the temperature
of the module approaches its safe operating threshold.
Over Temperature
Protection
Protects the SD4840EK from damage by removing power from the motor if
the internal temperature of the driver exceed a safe operating threshold.