To calculate the power input needed for a rotary motor use the following equation. Note you must do this for continuous and peak for servo motors (See graph below).
To calculate the power input needed for a linear motor use the following equation. Note you must do this for continuous and peak for servo motors (See graph below).
If you are sizing a DC power supply for your application, your work is nearly done. You have calculated the amount of continuous and peak power that your drive will require. If you plan to use a power supply for more than one axis, you must perform the previous steps for each axis, and you must select a power supply that will satisfy the total continuous and peak wattage for all of your axes. If you are sizing a transformer or a power supply that uses rating units of volt-amps (VA), you must now convert your requirements (in units of watts) into units of volt-amps by dividing the value in watts by a power factor of 0.66. Again, you need to consider both continuous and peak requirements for all of your axes.
IT IS IMPORTANT TO SELECT A TRANSFORMER OR POWER SUPPLY WITH A WATTAGE OR VOLT-AMP RATING THAT IS GREATER THAN THE TOTAL PEAK POWER REQUIREMENTS OF ALL YOUR AXES. IF THE RATING IS NOT GREATER, THEN YOU MUST CONSIDER USING A POWER DEVICE WITH A GREATER RATING OR YOU MUST CONSIDER USING MORE THAN ONE POWER DEVICE.
Note: The points of the torque/speed curve that are circled are the maximum power points for a servo.