Quote
frankvdh
I think the "rated" supply is relative to the reference voltage at the driver, which is typically 1.9V or thereabouts.
Torque is the critical spec for motors. Current determines torque. Rated voltage is simply coil current x coil resistance and has nothing to do with reference voltages in the driver which would vary from one driver to the next depending on the design.
All steppers behave better (reach spec'd torque faster) if driven from power supply voltage that is higher (up to 20X) the motor's rated voltage. When you switch a voltage across a resistor, the current changes instantly. In an inductor (a coil- i.e. a motor) when you switch the voltage, the current takes a while to rise to the maximum value determined by the coil's resistance. If the voltage pulse is short, the current may never reach the resistance limited value before the pulse ends and motor torque may not reach maximum possible value.
The driver ultimately regulates the operating current of the motor regardless of the power supply voltage. So if you set the driver for 1A it will deliver an average current of 1A whether the supply voltage is 12V or 40V (as long as the "rated voltage" of the motor is <12V). Using higher than rated voltage won't burn out the motor unless the driver fails.
See the rules of thumb for selecting power supply current here: [motion.schneider-electric.com]
It says the power supply current rating for microstepping drivers should be set to 1/2 the motor operating current + 1A. If you're going to power multiple motors from 1 supply, I'd use that formula on a per motor basis. You don't need a regulated supply, just a transformer, rectifier and filter cap (500uF per amp of total supply current). I use unregulated 32V supplies to power the X and Y axis motors/drivers to run 3.2V-3.6V rated motors in my printer. It works fine.