Parker EX Series - Page 42

42 – Pvd3665_Gb_Ex_August 2022
Illustration :
Acceleration-deceleration torque: 10 Nm for 0,1 s.
Resistant torque: 1 Nm during all the movement.
Max-min speed:  2800 rpm during 0,2 s.
Max torque provided by the motor: 11 Nm.
rms torque: 6 Nm.
The maximal torque M
i
delivered by the motor at each segment i of movement is obtained
by the algebric sum of the acceleration-deceleration torque and the resistant torque.
Therefore, M
max
corresponds to the maximal value of M
i
.
Selection of the motor :
The motor adapted to the duty cycle has to provide the rms torque M
rms
at the rms speed(*)
without extra heating. This means that the permanent torque M
n
available at the average
speed presents a sufficient margin regarding the rms torque M
rms.
(*) rms speed is calculated thanks to the same formula as that used for the rms torque. The
mean speed cannot be used (in general mean speed is equal to zero).
Only use the rms speed.
-20
-15
-10
-5
0
5
10
15
20
0.0 0.2 0.4 0.6 0.8 1.0 1.2
Time [s]
Torque [Nm]
-4000
-3000
-2000
-1000
0
1000
2000
3000
4000
Speed [rpm]
motor torque [Nm] rms average torque [Nm]
speed [rpm] rms average speed [rpm]

=
=
n
i
iirms
t
T
1
2
*
1