Alliedsignal Inc.

Allied Corporation

Other

Jerome Sears

Walter Parfomak

Walter J Kluss

William H Ficken

Arieh J Neuwirth

Michael Germinario

The speed of a rotor in a two-winding, permanent magnet motor can be accurately controlled with a dual-polarity pulse width modulation drive signal. The phase back emf signal generated in the non-excited winding is compared against the phase of a command signal and the results of the comparison are used to vary the duty cycle of the drive signal.

Control system for a permanent magnet motor

During the initialization phase, the rotor (or wheel) of a gyroscope is aligned by application of an alignment pulse to insure that it rotates in a known direction upon start up. However, without some means for damping the rotor, the rotor will oscillate about the null position for an excessive period of time. The back emf signal induced in the non-excited winding can be used to generate a feedback signal for modifying the alignment pulse to minimize oscillation. In one variation, the back emf signal is frequency multiplied and inverted, and then combined with the alignment pulse. The combined signal is applied to the winding to rapidly align the wheel.

Initialization damping for a permanent magnet motor

A two-phase motor includes two orthogonally disposed stator windings and a permanent magnet rotor. One of the stator windings is energized with a maximum energizing input for a narrow time period, whereupon the rotor is driven to a position intermediate the two stator windings. At the end of the narrow time period, the other of the stator windings remains energized whereupon the rotor is driven to align with the magnetic flux generated by the other winding. A switching arrangement is actuated to prevent loading on the one phase winding while the back EMF from the one winding is conditioned and interrogated for magnitude and for rotor direction. When the proper magnitude and direction are sensed the switching arrangement renders the motor in a run mode while closing the drive loop for the one phase winding which is now driven with a maximum input. As the rotor accelerates toward the one phase winding the back EMF from the undriven phase winding is converted from an angular rotor rate signal to an angular rotor position feedback signal, and which back EMF is used to determine if the motor is actually running so as to prevent restart, or to repeat the starting sequence, as the case may be.

Dynamic rate feedback PM motor starting technique

A two degree of freedom gyroscope having a drive motor (20), with a permanent magnet rotor (22), which includes an optical sensor (11) for providing an X-axis signal and a Y-axis signal which are indicative of the displacement of the actual rotor (22) spin axis from the null spin axis (28), a torquer coil (26) looped around the permanent magnet rotor (22) and disposed in a plane orthogonal to the null spin axis, and torquer drive elements (52, 54, 56) responsive to the X-axis and Y-axis signals induced in the sensor when the actual rotor (22) spin axis is displaced form the null spin axis (28) for providing current to said torquer coil (26) to urge the axes to coincide. A voltage induced in an open phase of a two phase motor stator is used to provide the instantaneous position of the rotor poles to obtain correct phasing information for commutation of the single polar torquer.

Electronically commutated two-axis gyro control system

A two degree of freedom gyroscope having a drive motor (20), with a permanent magnet rotor (22), which comprises a sensing coil (32) looped around the permanent magnet rotor (22) and disposed in a plane orthogonal to a null spin axis, a torquer coil looped around the permanent magnet rotor (22) and disposed in a plane orthogonal to the null spin axis, and torque drive elements (62, 64, 65) responsive to the signal induced in the sensing coil (32) when the actual rotor (22) spin axis is displaced from the null spin axis (28) for providing current to said torquer coil (34) to urge the axes to coincide. Demodulators (70, 72) can be provided for providing output information in an X-Y coordinate format which is indicative of the actual input angular rates about corresponding axes.

Polar loop implementation for a two degree of freedom gyro

A system (10) for controlling stabilization of a synchro (26), which is driven from a digital to synchro converter (12), which utilizes a current sensor (14) to detect the magnitude of the synchro current drive signal and through a compare and hold circuit (20) compares the magnitude of the current with a predetermined maximum current and if exceeded provides a signal to a logic control (22) which controls a current limiter (16), disposed in series with the conductors providing load current to synchro (26). Current limiter (16) operates in a non-current limiting mode, wherein load current is passed unhindered to synchro (26), and a current limiting mode wherein current limiting resistors are inserted in series with the conductors carrying drive current to synchro (26). When the commanded drive current exceeds the reference current, compare and hold circuit (20) initiates a signal to cause current limiter (16) to operate in the current limiting mode. Compare and hold circuit (20) also includes a delay circuit which keeps current limiter (16) in the current limiting mode for a short period of time after the commanded drive current falls below the reference current level. A pulse width oscillator (24) provides an input to logic control (22) which causes logic control (22) to periodically switch current limiter (16) to the unlimited current condition for short periods of time even when the compare and hold circuit (20) is providing a signal requesting the current limiting mode.

Synchro drive stabilization system

A two degree of freedom gyroscope having a drive motor (20), with a permanent magnet rotor (22), which includes an optical sensor (11) for providing an X-axis signal and a Y-axis signal which are indicative of the displacement of the actual rotor (22) spin axis from the null spin axis (28), a torquer coil (26) looped around the permanent magnet rotor (22) and disposed in a plane orthogonal to the null spin axis, and torquer drive elements (52, 54, 56) responsive to the X-axis and Y-axis signals induced in the sensor when the actual rotor (22) spin axis is displaced from the null spin axis (28) for providing current to said torquer coil (26) to urge the axes to coincide.

A permanent magnet two degree of freedom gyroscope (10) utilizing a single rotor (12) having a trapezoidal shaped pattern formed thereon. The trapezoidal pattern consists of a reflective segment (11) and a non reflective segment (13). Two optical sensors (14, 18) fixed with respect to the stator, obtain angular displacement information about the two axes perpendicular to the spin axis, rotor pole location information, which is used for commutation, and, rotor speed information. The present invention deals with an apparatus and method for starting, running and torquing the two degree of freedom permanent magnet gyro motor (10) based on position and displacement information obtained from the two optical detectors (14, 18). The angular displacement information is obtained by sensing differences in the optical pattern as the rotor (12) spins and is displaced about cross-axes, perpendicular to the spin axis.

Optical commutation and tilt sensing for a permanent magnet gyro

The present invention deals with an apparatus and method for starting and running permanent magnet motors based on angular position information using an optical commutation technique. The optical commutation technique provides rotor position information at rest and while rotating for two-phase driving of a motor having a permanent magnet rotor. The angular position information is extracted by optical detectors, consisting of a light source and an optical sensor for detecting an optical pattern formed on the gyro rotor. The optical pick off associated with one phase is used to commutate the other phase. The optically detected signal output is converted to a frequency signal which is proportional to wheel speed. The frequency signal is converted to a voltage signal which is compared to a speed command signal in a feedback loop to generate the required drive. Alternately the frequency can be inputted to a phase lock loop circuit and compared with a speed reference clock frequency to generate the required drive signal level.

Optical commutation for permanent magnet motors

A closed loop drive system for a permanent magnet motor (12) operable in a two-phase drive mode during a start cycle and a single phase drive mode thereafter during which the start cycle is reinitiated if the back EMF generated in a sensing winding (18) falls below a reference value. The permanent magnet motor (12) is driven as a two-phase motor with an increasing frequency input during the starting cycle and after initial starting is driven as a single phase motor as long as the back EMF induced in a stator sensing winding (18) remains above a predetermined value. A restart decision circuit (20) is provided which samples the back EMF induced into the stator winding (18) not being driven during single phase operation and initiates a restart cycle if the induced back EMF during single phase operation falls below a selected reference.

Permanent magnet motor closed loop restarting system

A motor for an inertial sensing instrument includes a permanent magnet rotor and a stator having a driving winding inductively coupled to a sensing winding, with both windings connected to a common impedance. A feedback arrangement is provided which compensates for noise inducted by the common impedance in a sensing signal provided by the sensing winding.

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Wyckoff, NJ, United States of America

Jerome Sears