Pulsed electric machine control

An electric machine controller arranged to direct a power converter to cause pulsed operation of an electric machine in selected operational ranges to deliver a desired output, wherein the pulsed operation of the electric machine causes the output of the electric machine to alternate between a first output level and a second output level that is lower than the first output level, wherein the first and second output levels are selected such that the electric machine has a higher energy conversion efficiency during the pulsed operation of the electric machine than the electric machine would have when operated at a third output level that would be required to drive the electric machine in a continuous manner to deliver the desired output, wherein:

• the electric machine controller includes a pulse controller that directs timing of the pulsing of the electric machine;
• and
• the pulse controller utilizes a sigma delta converter that dynamically determines at least one of durations, timing or frequency of the first output level pulses.