Extended-resolution pulse-width modulation servomotor drive

Drivers (24, 26, and 28) in the controller for a motor (14) drive the motor in accordance with a pulse-width-modulation scheme in which each pulse-width-modulation cycle includes a positive interval and a negative interval so that the value of the filtered output is proportional to the difference in duration between the positive and negative intervals. The pulse-width-modulator cycle also includes dead times between the positive and negative intervals, and these dead times are varied so that a change in a positive interval's duration in a fixed-duration pulse-width-modulation cycle does not necessarily result in an opposite change in the negative interval's duration. Consequently, the value resolution for a system in which the pulse-width-modulation cycle is a given number of system clock periods can be finer than it would be if the dead-time interval's duration were fixed.