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Calculation for the allowable operation cycles per minute by motor speed and inertia.<br />
The formula below should be used to to calculate the permitted number of cycles/min<br />
in regenerative mode in accordance with the actual loading and the running speed of the motor.<br />
No load operation cycles<br />
Allowable operation cycle/min. =<br />
×<br />
Rated Speed<br />
(<br />
)<br />
(1+<br />
α )<br />
MaxRunningSpeed<br />
2<br />
α= Load Inertia / Motor Inertia<br />
If the required number of cycles /min is higher than the calculated value then an external<br />
regeneration resistor must be installed.<br />
Calculation of the external regeneration resistor power (Watts).<br />
Calculate the resistor watts according to the information and formulas below:<br />
(Energy consumed by the motor internally is ignored).<br />
Speed<br />
Running<br />
Speed<br />
Torque<br />
t D<br />
Time(s)<br />
T L<br />
T<br />
Cycle<br />
Time(s)<br />
Step Item Formula Description<br />
E<br />
M<br />
: Working Energy of Servo system (J)<br />
1<br />
Calculate the working Energy of<br />
J<br />
2<br />
T<br />
: Inertia applied to the motor shaft<br />
E = /182<br />
the servo system.<br />
M<br />
J<br />
T<br />
ωrm<br />
(<br />
2<br />
3<br />
4<br />
5<br />
Calculate the Energy<br />
consumption by the load during<br />
deceleration.<br />
Calculate the Energy absorbed by<br />
internal main capacitor.<br />
Calculate the Energy which<br />
regeneration resistor consumes<br />
Calculate the Power for<br />
regeneration resistor<br />
E = ( π / 60)<br />
ω<br />
L<br />
rm<br />
T<br />
EC<br />
Check the diagram above<br />
L<br />
t<br />
D<br />
2<br />
kg • m )<br />
ω<br />
rm<br />
: Motor running Speed(rpm)<br />
E<br />
L<br />
: The Energy during deceleration (J)<br />
T<br />
L<br />
: Loading Torque(Nm)<br />
t : The Time from deceleration to stopping(s)<br />
D<br />
E<br />
E E - ( E + E ) R<br />
P<br />
R<br />
=<br />
M L C<br />
= ( E / T ) / 0.4<br />
R<br />
R R<br />
C<br />
: The Energy absorbed by the main<br />
capacitor (J)<br />
E : The Energy which Regeneration Resistor<br />
consumes (J)<br />
P : Regeneration Resistor Power(W)<br />
T : Operating cycle for servo system(s)<br />
Note 1 : 0.4 in the formula for P<br />
R<br />
corresponds to 40% regeneration duty cycle.<br />
Note 2: If the E<br />
L<br />
can not be calculated, then let E<br />
L<br />
= 0 , then calculate ER .<br />
In applications with regenerative loads, which cause reverse torque, a large amount of energy will flow back to<br />
the driver.<br />
5-72
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