Sundstrand Corporation

Sunstrand Corporation

Bernard A Raad

Clarence F Dolan

Alexander Cook

Tyrone A Johnsen

Alexander Krinickas, Jr

Barry J Parker

Jeffrey D Baldwin

Loren Rademacher

Edmund A Schott

John W Oller, Jr

The problem of providing field power to a stationary main generator field winding (22) is addressed such that it can be used as a motor. A dynamoelectric machine (12) is operated as both a generator and a motor. An AC-AC exciter (14) is controlled by an exciter inverter (42) to operate as an exciter generator in a generate mode, and as a rotary transformer in a start mode. The exciter inverter (42) supplies low frequency power to an exciter field winding (28) in a generate mode of operation, and supplies high frequency AC power to the generator field winding (28) in the start mode of operation.

AC exciter for VSCF starter/generator

The problem of providing field power to a stationary main generator rotor is addressed such that it can be used as a synchronous or brushless dc motor. To that end, a dynamoelectric machine performs the dual-functions of an exciter generator and a rotating transformer integrated into a single unit (14). The heads (64) of the stator salient poles (60) include pole slots (68) for a primary transformer winding (34) for the rotating transformer, while the rotating armature winding (36) serves as the transformer secondary. To assist in starting the engine (10), external ac power (42) is applied to the primary transformer windings (34), coupled to armature windings (36), and rectified (44) to develop dc field power for the main generator (12).

Integrated exciter generator and rotating transformer

A starting system for an aircraft propulsion engine. An electrical motor (62 or 122) is mounted within a case (14) in which first and second hydraulic units (102, 104) are operated as part of a constant speed drive transmission. The electric motor accelerates a motor-generator set (24) to a velocity near the synchronous speed. The motor-generator set is coupled to the drive shaft (20) by operation of the hydraulic units as a variable torque link. The electric motor functions both as a heat source of hydraulic fluid contained within the hydraulic pump and motor case during extreme low temperature conditions at which point the starting torque of the motor is initially insufficient to cause rotation of the output shaft and to further accelerate the motor-generator set up to a rotational velocity at which the motor-generator set may be operated synchronously at which the motor-generator set is coupled to the drive shaft (120) by operation of the hydraulic units as a variable torque link to rotate the engine. When the temperaature of the hydraulic fluid within the case is below the stall temperature so that the electric motor has insufficient starting torque to initiate rotation, the heat generated by the windings heats the hydraulic oil to lower its viscosity to a point at which rotation may be initiated to permit the motor-generator set to be rapidly accelerated to operate as a synchronous motor during starting.

Integrated starting system

A starting system and method for starting a prime mover connected to a generator by an actuable torque link utilizes a hybrid permanent magnet/induction machine having a rotor coupled to a rotor of the main generator and a stator having windings therein. The method includes the step of applying AC power to the hybrid machine stator windings so that the hybrid machine initially acts as an induction motor to accelerate the hybrid machine rotor, following which the hybrid machine acts as a synchronous motor to rotate the main generator rotor at a particular speed DC power is then applied to a main generator field winding and AC power is supplied to a set of main generator armature windings so that the main generator operates as a synchronous motor to develop motive power the torque link is activated once the main generator is operating as a synchronous motor to bring the prime mover up to self-sustaining speed. Inasmuch as the hybrid machine may comprise part of a brushless synchronous generator, the present system and method does not require additional components and reduces transients in the AC power applied to the hybrid machine and generator.

Starting system and method using a hybrid permanent magnet/induction

An undesirably long brushless generator including a permanent magnet generator 114, 116, 118, an exciter 64 and a main generator 22, 24, 42, 44 may have its axial length reduced by locating both the permanent magnet generator 114, 116, 118 and the exciter 64 adjacent one end of the main generator 22, 24, 42, 44 in an essentially coplanar relation with the permanent magnet generator 114, 116, 118 radially inward of the exciter 64.

Brushless generator with minimal axial length

An electromagnetic clutch assembly for engaging and disengaging a rotatable prime mover with a rotatable load. A first clutch element is attached to the load and mounted for rotation about an axis. A second clutch element forms part of a one-piece torque component with an armature portion remote from the second clutch element, attached to the prime mover, and mounted for axial movement and rotation about the axis. An electromagnetic device is mounted adjacent the armature portion to effect disengagement of the unitary second clutch element relative to the first clutch element.

Electromagnetic clutch

A starting system for starting a prime mover connected to a generator by a torque link includes an induction motor having a torque rating substantially equal to the minimum torque required to rotate the rotor of the generator from rest to a particular speed within a predetermined time period while the torque link is deactuated, a source of electrical power, contactors for connecting the source of electrical power to the induction motor when the torque link is deactuated to accelerate the generator rotor to the particular speed, a second set of contactors for connecting the source of electrical power to the generator windings once the generator rotor has reached a particular speed to cause the generator to operate as a synchronous motor and a torque link actuator for actuating the torque link once the generators operating as a synchronous motor to bring the prime mover up to starting speed. The usual large magnitude transient developed in the source of electrical power is thus broken down into three transients of lesser magnitude.

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Rockford, IL, United States of America

Bernard A Raad