You can use any voltage that, when resistance and inductance are taken into consideration allow a current of 1.5 A to flow. You want that current to be established as fast as possible, so you need constant current drivers, or I suppose more accurately voltage controlled current sources.

Try and measure the winding inductance as a beginning. Then calculate how long you have to get the current to that value. That depends on your step rate.

Look at Allegro semiconductors for lots of information on drivers and motor construction.

Steve