Calculation of motor-shaft conversion torque and effective torque
Calculate the acceleration torque from the motor-shaft conversion load inertia, the motor-rotor iner-
tia and the acceleration. Then, calculate the load torque from the external force (gravity and ten-
sion) and friction force applied to the load. Finally, combine these calculation results to calculate
the torque required for the motor
.
• Calculation of acceleration torque (T
A
)
JL
JM
η
N
tA
TA：Acceleration torque [N·m]
JL：Motor-shaft conversion load inertia [kg·m
2
]
JM：Motor-rotor inertia [kg·m
2
]
η：Efficiency of transfer part (η≦1)
tA：Acceleration time [s]
N：Motor rotation speed [r/min]
Motor
Speed (rotation speed)
Time
＋JM
60・tA
2π・N
η
JL
＝
TA[
N·m]
• Calculation of motor-shaft conversion load torque (T
L
)
F
D
TW
TW [N·m]=F· ×10
-3
D
2
(Generally, the friction force can be calculated as below:)
F=
μ
Mg [N]
μ: Coefficient of friction
M: Mass of motion part [kg]
g: Acceleration of gravity (g≈9.8 [m/s
2
])
TW: Load torque (Load-shaft conversion) [N·m]
F: External force [N]
D: Diameter of cylinder [mm]
T
: M
otor-shaft conversion load torque [N·m]
T
: Load torque (Load-shaft conversion) [N·m]
Z
: Number of motor-side gear teeth
Z
: Number of load-side gear teeth
G : Gear ratio (Speed reduction ratio) = Z / Z
G
η
T
[N·m] = T
·
Z
T
Z
Motor
T
• Calculation of combined torque and effective torque
Appendices
A-297
M1 Series EtherCAT Type User’s Manual (I670)
A-10 Overview of Inverter Selection
A
A-10-1 Motor Capacity Selection
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