Abstract: An economical digital voltage sag compensator for overcoming sags in distributed electrical power. The voltage sag compensator employs an inexpensive micro-controller, a full wave bridge rectifier, a DC power supply, a voltage divider and an output switch. The micro-controller continuously monitors and evaluates, with respect to a setpoint measured in volt-seconds, the rectified DC voltage. At regularly spaced trigger events, as determined by the micro-controller, the micro-controller concurrently monitors the rectified DC voltage, evaluates the monitored voltage with respect to the setpoint, produces an output signal and sends that output signal to the output switch. The output switch supplies an electrical device, connected electrically in series with the full wave bridge rectifier and the output switch, with a constant average current of sufficient level to maintain the electrical device in a desired operating condition.

Abstract: Power of three-phase AC mains is directly converted to DC power by a DC matrix converter employing insulated gate bipolar power transistors to directly connect the AC mains to an elevator DC motor for periods of time which are short compared with the period of the AC voltage, so as to continuously synthesize the desired AC voltage to the elevator motor. Filters are provided at the input and output of the DC matrix converters. Separate DC matrix converters may supply both the armature current and the field current to an elevator motor. Signals for selectively gating the power transistors are provided by converter control logic in response to a conventional phased locked loop, an elevator motion controller, and position speed and current control logic.

Abstract: A magnetic bearing with reduced control-flux-induced rotor loss includes a rotor 14, and a stator 12 having a plurality of slots S1-S16 around which coils 150-156 of a first Phase A and coils 160-166 of a second Phase B are wound. The winding configuration provides a two pole magnetic field around a rotor/stator gap 15 which is sinusoidal and which can be directed to any location along the gap 15. The configuration minimizes discontinuities or sharp changes in control flux in the gap which thereby reduces rotor losses. Also, the stator tooth gap g1 is minimized to provide smooth flux distribution along the rotor/stator gap 15. More phases and more or less stator slots may be used.

Abstract: The invention provides an elevator system for controlling movement of an elevator car with respect to guide rails in an elevator hoistway, having a force-estimation or position-scheduled current command controller and a magnet driver circuit without the need for a flux sensor. The force-estimation or position-scheduled current command controller responds to a force command signal, and further responds to a sensed gap signal, for providing a force-estimation or position-scheduled current command controller signal as a current command to the magnet driver circuit. The magnet driver circuit responds to the force-estimation or position-scheduled current command controller signal, for providing a magnet driver circuit signal to control said horizontal movement of the elevator car with respect to the guide rail in the elevator hoistway, whereby the horizontal movement of the elevator car is controlled without sensing magnetic flux.

Abstract: An electromagnet actuator has an E-shaped core for coupling magnetic flux between the core and a blade of a hoistway rail. A pair of coils wound on the core provide the flux in such a way as to produce both side-to-side and front-to-back forces that can be controlled by varying the current to the pair of coils in each actuator on opposite sides of the car.