Kaman Electromagnetics Corp.

Newport News Shipbuilding and Dry Dock Company

Eml Research, Inc.

Peter P Mongeau

Thomas B Dade

Thomas A Keim

Kenneth W Leiding

Alan Millner

Mark S Piercey

Zaher Daboussi

A motor drive system for selectively supplying a drive current to a multiple phase motor having each phase winding divided into a plurality of discrete windings includes a plurality of H-bridge drives to control the polarity and magnitude of the drive current. Each H-bridge drive include a pair of half bridge drives interconnected to the terminals of each of the discrete windings. Each of the half bridges have an upper bridge switching element and a lower bridge switching element for coupling the positive and negative potential, respectively, of a DC power source to each discrete winding. The discrete windings of each phase winding are coupled in series by a plurality relays which are selectively actuated by a controller to interconnect the discrete windings in predetermined groups dependent upon the shaft speed of the motor. The controller also controls the excitation of the bridge switching elements whereby the bridge switching elements disposed at the end terminals of each group of discrete windings are actuated and the other bridge switching elements are turned off to provide the desired current to the phase windings of the motor.

Motor drive system having a plurality of series connected H-bridges

A magnet carrier assembly for holding and carrying a high-energy-product permanent magnet is arranged for releasable attachment to a rotor of an axial disc or drum type rotor in an electric machine. The permanent magnet placed in a container which then receives a cover. The magnet carrier assembly includes a mounting flange at one end and a locating and mounting tab at an opposite end for attaching the assembly to the rotor. In certain applications, the rotor has recesses which have a size and shape complementary to the size and shape of the magnet carrier assembly. The recesses are circumaxially located around the radial periphery of the rotor at the poles of the rotor. In other embodiments, the magnet carrier assembly includes a key which is received in a mating groove in a rotor surface and is used to transfer to the rotor the electromagnetic shear force developed by the high-energy-product permanent magnet. The present magnet carrier assembly can be used with both axial field disc or radial field drum rotors. The present invention also contemplates a method and apparatus for removing and installing magnet carrier assemblies in electric machines.

Detachable magnet carrier for permanent magnet motor

A four quadrant unipolar pulse width modulated (PWM) power conversion circuit for supplying a desired current to an inductive load uses an H-bridge circuit topology with an upper and lower pair of switching elements including a diode in parallel with each of the switching elements to provide a current path from the load to the power source when its respective switching element is non-conductive. A control algorithm generates switching element control signals to cause the instantaneous voltage across the load to alternate between a single polarity voltage and zero for a portion of the output load waveform to cause the average value of the load current to correspond generally with the desired average load current.

Four quadrant unipolar pulse width modulated inverter

An improved electric propulsion motor for marine vehicles. The motor has an axial gap design with a disk-shaped rotor and two disk-shaped stators. Within the large, open diameter of the motor a sound isolation coupling is disposed between two annular plates that connect the rotor to the propeller shaft. Circumferential thrust bearings counter and distribute electrical and mechanical forces in the motor to maintain the position of the rotor relative to the stators. A journal bearing supports the rotor. Noise reduction is greatly enhanced by the implementation of staggered stators, skewed stator slots, skewed field poles and a current control system that compensates for torque pertubations that are a repeatable function of shaft angle.

Electric propulsion motor for marine vehicles

An input control current command signal is modified in accordance with a number of compensation factors stored in a memory and corresponding to each of a number of angular shaft positions to provide a control signal to cause an inverter to drive each of the number of phases of a permanent magnet axial-field motor to cause the motor to produce a ripple-free torque output. The compensation values stored in the memory are identified and determined in accordance with the source of the torque ripple such as vibration, load operation, noise and variations within the motor construction.

Apparatus and related method to compensate for torque ripple in a

An electric power system for large marine vehicles in which one or more AC generators are shared as the ship's propulsion power source and the ship's electrical service power source. The voltage from the AC generator(s) is rectified to a reduced DC voltage such that voltage transients in the propulsor motor do not reflect into the ship service power system. Silicon controlled rectifier (SCR) bridges are utilized to convert the generator's AC voltage into a reduced DC voltage. As a supplement for emergency power, a rechargeable battery is included to provide power for propulsion and ship service.

Growing community of inventors

Hopkinton, MA, United States of America

Peter P Mongeau