Fundamental torque equation •Motor drives a load through a transmission system. •Motor always rotate, load may rotate or undergo a translational motion. •Load speed may be different from that of motor.
•The basic equation of the motor-load system is LTT)(JdtddtdJdtdJ)(•Drives with constant inertia, (dJ/dt)=0 •Industrial robots-variable inertia Fundamental torque equation )(dtdJTTL
•where Tand TLis motor and load torque respectively in N-m, Jis the moment of inertia and ωis the angular velocity in rad/sec. •Motor torque is the applied torque and load torque is the resisting torque. •Different states at which an electric drive causing rotational motion are (i) T > TL(dω/dt >0):- The drive will be accelerating, in particular, picking up speed to reach rated speed. Dynamic torque and it is present only during transient operations
(ii) TM< TL(dω/dt <0):- The drive will be decelerating and particularly, coming to rest. (iii) TM=TL(dω/dt =0