Stall Torque Vs Starting Torque Vs Zero Velocity Torque

[antoronson]

I am interested in modelling an analytical model for PMSM Motor. I am interested in measuring the torque at zero velocity. When the motor is loaded with an external load and the motor is made to hold on to that position for a certain period of time, a certain amount of load acts on the armature where the velocity is zero. Is there a way to estimate the power from this torque. Further when we reduce the time step, at the start of a motor, we have zero velocity at the very initial time step. Does this velocity match with that of the stall torque(torque for holding) ?

 

[LionelHutz]

There is no power output from the motor when there is no movement. Any power input would be due to the motor losses.

I expect you asked the second question wrong. Velocity and torque measure different things so no reason for them to match. If you're asking about the torque when first accelerating, the load always has a static torque requirement which you have to match to hold the speed. So, to accelerate the load you have to apply more torque than this (or less for deceleration).

 

[antoronson]

Thank You for your reply.
Consider the case of Robot Arm, radial movement. When the arm is to be holded at 40degree, where the velocity is zero, we have zero velocity torque acting. How come there is no power in motor in this case.

 

[LionelHutz]

Power is the rate of doing work. No movement means no work done so no power output from motor.

 

[antoronson]

I got the technical term. I would like to estimate the holding torque of a Permanent Magnet Synchronous Machine.