featured is a controller for a motor that is ultra - compact , with a power density of at least about 20 watts per cubic cm . the controller utilizes a common ground for power circuitry , which energizes the windings of the motor , and the signal circuitry , which controls this energization responsive to signals from one or more sensors . also , the ground is held at a stable potential without galvanic isolation . the circuits , their components and connectors are sized and located to minimize their inductance and heat is dissipated by conduction to the controller &# 39 ; s exterior such as by a thermally conductive and electrically insulating material . the controller uses a single current sensor for plural windings and preferably a single heat sensor within the controller . the body of the controller can also function as the sole plug connector .