The method of calculating microstepping currents for variable reluctance stepping motor with equal microstep angle was described when motor torque characteristics were sinusoidal shapes.
Software subdivision and "virtual frequency conversion" technology were adopted in this solution, which realized multigrade, adaptive subdivided drive in operation of stepping motor.
To control stepping motors, the balance bridge power drive circuit is made up by TDA1521 integrated audio power amplifier, the pulse allotter is made up by the parallel ports of computer and latches.