Abstract: A direct drive roller motor for use in a belt drive system includes a brushless DC motor that has an external rotor that functions as a direct drive roller. The motor has stator coils mounted on a stator shaft that is physically and thermally coupled at both ends thereof to a support structure which provides in addition to support, a function of dissipating thermal energy generated by the i2R losses of the stator coils and the magnetic core losses of the stator.

Abstract: A current sensing circuit includes an impedance network having a capacitor which produces a voltage proportional to the steady-state component of current and an inductance which produces a voltage proportional to the transient component. The capacitor voltage modulates a carrier signal which conveys the steady-state component through an isolation transformer to a demodulator. The transient component is conveyed through a second isolation transformer and is summed with the demodulated steady-state component.

Abstract: A transducerless brushless permanent magnet motor in which a signal induced by the rotor in an unexcited winding is used to sense the rotor position. The sensed voltage, induced in the winding by the rotor, is integrated to provide a representation of the magnetic flux coupling the rotor and winding. Before start-up, both the rotor position and the integrator are initialized to align the circuit representation of the flux with the actual flux.In an additional embodiment of the invention, a self-initialization circuit is provided to automatically preset the rotor and flux integrator to pre-determined and corresponding values.