5-73
Calculation for the allowable operation cycles per minute by motor speed and inertia.
The formula below should be used to to calculate the permitted number of cycles/min in regenerative mode
in accordance with the actual loading and the running speed of the motor.
2
)(
)(1
SpeedMaxRunning
Speed Ratedcycles operation load No
cycle/min. operation Allowable
α= Load Inertia / Motor Inertia
If the required number of cycles /min is higher than the calculated value then an external
regeneration resistor must be installed.
Calculation of the external regeneration resistor power (Watts).
Calculate the resistor watts according to the information and formulas below:
(Energy consumed by the motor internally is ignored).
Speed
Time(s)
Running
Speed
Cycle
Torque
D
t
T
L
T
Time(s)
Step Item Formula Description
1
Calculate the working Energy of
the servo system.
182/=
2
rmTM
ωJE
M
E : Working Energy of Servo system (J)
T
J : Inertia applied to the motor shaft
(
2
• mkg )
rm
ω : Motor running Speed(rpm)
2
Calculate the Energy
consumption by the load during
deceleration.
DLrmL
tTωπE )60/(=
L
E : The Energy during deceleration (J)
L
T : Loading Torque(Nm)
D
t : The Time from deceleration to stopping(s)
3
Calculate the Energy absorbed by
internal main capacitor.
C
E Check the diagram above
C
E : The Energy absorbed by the main
capacitor (J)
4
Calculate the Energy which
regeneration resistor consumes
)+(-=
CLMR
EEEE
R
E : The Energy which Regeneration Resistor
consumes (J)
5
Calculate the Power for
regeneration resistor
4.0/)/(= TEP
RR
R
P : Regeneration Resistor Power(W)
: Operating cycle for servo system(s)
Note 1: 0.4 in the formula for
R
P corresponds to 40% regeneration duty cycle.
Note 2: If the
L
E can not be calculated, then let 0=
L
E , then calculate ER .
In applications with regenerative loads, which cause reverse torque, a large amount of energy will flow back to
the driver.
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