Abstract: A motor powered by a dc power source has a stator having a single phase winding. A power switching circuit of the motor has power switches for selectively connecting the dc power source to the single phase winding. A permanent magnet rotor in magnetic coupling relation to the stator drives a fan. A position sensor on the stator detects the position of the rotor and provides a position signal indicating the detected position. A control circuit including a microprocessor responsive to the position signal and connected to the power switching circuit selectively commutates the power switches to commutate the single phase winding as a function of the position signal. The microprocessor controlled motor is programmed to reduce operation at speeds at which resonance occurs and provides an alarm in the event that the static pressure of the air driven by the fan is unacceptable.

Abstract: The invention detects vibrations of a motor by a vibration detection means, compares the detected vibration detection value with a reference value using control means, and changes the voltage to be applied to each of coils of the respective excitation phases until the vibration detection value reaches the reference value, thereby controlling the excitation currents that flow through the coils of the respective excitation phases to reduce the vibrations of the motor.

Abstract: The invention is a host-based stepper motor controller that reduces velocity overshoot and settling time. A typical embodiment of the invention will include a stepper motor, a carrier mechanically coupled to the stepper motor, a processor for controlling the stepper motor and a driver circuit allowing communication between the processor and the stepper motor. The processor control reduces velocity overshoot and settling time by guaranteeing that each move begins on the stepper motor phase that optimally reduces velocity overshoot and settling time. The processor generates an initial value indicative of the extent of a current move of a carrier mechanically coupled to a stepper motor. Next, the start phase of the current move is determined along with the direction of the next move.

Abstract: A control circuit for a motor having at least two windings is used to optimize noise reduction by controlling the deenergization of each winding in a two-stage decay. The duration of the two-stage decay and particularly the first decaying current portion is controlled by a controller operatively coupled to a switch device. The duration of the first decaying current portion is varied between the various phases of the motor to provide optimum noise reduction.

Abstract: In a synchronous machine, an armature structure has n (n being a positive integer) salient poles provided at predetermined circumferential distances around a rotary shaft and coils wound on the salient poles respectively, and a field system is constituted by (n-1) permanent magnet pieces arranged like a ring as a whole around the rotary shaft closely to radially outer ends of the salient poles of the armature structure, the respective permanent magnet pieces being magnetized radially so that north and south poles are alternately arranged respectively on inner circumferential surfaces of the permanent magnet pieces, and each of boundary lines between adjacent ones of the permanent magnet pieces is inclined at a predetermined angle relative to a direction parallel to the rotary shaft in such a manner that when the radially outer ends of the salient poles opposite to the inner circumferential surfaces of the permanent magnet pieces are circumferentially developed and projected onto a development where the inner

Abstract: A switched reluctance machine run as a servo-motor has its torque ripple reduced by shaping the chopping current by which the rotor is rotated relative to the stator. The shaping includes reducing the rate of change of torque with respect to time such that the magnitude of the torque ripple is reduced and therefore more easily rejected by the control function of the machine controller.

Abstract: The present invention is directed to the design of a low cost variable speed single phase AC induction motor by eliminating the capacitor, and running the motor as a two phase motor.

Abstract: Methods and apparatuses are provided to identify and extract a torque ripple signal found in the back-emf signal from an electric motor. The torque ripple signal is used in a feedback control loop to reduce the amount and effects of torque ripple in the motor and the motor system. A motor controller is provided to reduce torque ripple in an electric motor. The motor controller is suitable for controlling the speed or torque or other related parameters associated with the electric motor. A disc drive apparatus for use in information storage and retrieval systems is provided. The disc drive apparatus includes an electric motor, an information storage disc, and a motor controller. A method is provided for reducing the effects of torque ripple in an electric motor by sampling the back-emf signal generated by the electric motor, extracting the torque ripple signal from the back-emf signal, and generating an AC component signal proportional to the torque ripple signal.

Abstract: A control device for a switched reluctance motor which includes a target current determination device for determining a target value of a current which is supplied to each of a plurality of coil phases of a motor, a current supply timing determination device for determining timings at which the current begins to be supplied to each of the coil phases and at which the supply of the current is ended, a pulse width modulating device for generating a pulse width modulating signal so that the current which is supplied to each of the coil phases is modulated so as to correspond to the target value and a synchronization device for synchronizing a starting time of the pulse width modulating signal with the timing at which the current begins to be supplied to each of the coil phases.

Abstract: A control circuit for a motor having at least two windings is used to optimize noise reduction by controlling the deenergization of each winding in a two-stage decay. The duration of the two-stage decay and particularly the first decaying current portion is controlled by a controller operatively coupled to a switch device. The duration of the first decaying current portion is varied between the various phases of the motor to provide optimum noise reduction.

Abstract: The disclosed hunting suppressor is for use with n-phase electric motors including a stator having n windings and a rotor. The hunting suppressor is responsive to a reference clock signal characterized by a frequency f.sub.c and an associated phase angle .phi..sub.c.A controlled frequency oscillator generates n drive signals, where the drive signals are mutually shifted in phase by 180/n degrees. The drive signals are each coupled to drive a respective one of the n windings of the motor. A phase locked loop network locks the frequency and phase of one of the drive signals to that of an applied clock reference signal. With that configuration, the rotor is controlled to rotate at the frequency of the clock reference signal with substantially no hunting.

Abstract: A method for minimizing torque ripple in a permanent magnet brushless DC motor includes the steps of energizing a first winding of the motor to generate a first current, energizing a second winding of the motor to generate a second current, and overlapping the first and second currents in time by a preselected time to reduce torque ripple. The structure for performing the method includes conventional brushless DC motor drive circuitry responsive to a motor rotor position signal, and a speed control signal, to sequentially generate a gate drive signal for driving a respective semiconductor switch to energize each winding of the motor. The structure further includes a phase overlapping circuit interposed between the conventional brushless DC motor control circuitry output and the semiconductor switches used to energize each winding of the motor. The phase current overlap circuit includes a monostable multi-vibrator for generating a "one-shot.

Abstract: Electromagnetic damping techniques for use in slowing down the shaft to a gas turbine based on various electrical machine concepts. A rotor may be mounted on an outer race of a bearing through which the shaft extends. The damper may use a permanent magnet (PM) design with permanent magnets mounted to the rotor. Alternately, the rotor and stator may be designed to operate upon a switched reluctance motor (SRM) design. Instead of having the rotor mounted to the outer race, an alternate arrangement may use a rotor mounted directly to the gas turbine shaft in which case the rotor and a corresponding stator serve both as a damper and as an electrical generator for providing the usual electrical generation functions from the gas turbine shaft.

Abstract: In an electric motor with a damping device incorporating a disc-shaped damping mass which is freely rotatable and axially movable in relation to the driven element and consists at least partially of a mangetizable material, the damping mass is located within the range of a stray magnetic field (31) of the motor (11) and is pressed against a friction plate (28) located between the rotor (14) of the motor and the damping mass and rotating with the driven element as a result of the magnetic force of the stray field acting upon the mass.

Abstract: A method and apparatus for damping oscillations in the rotor load angle of a synchronous motor to provide stable rotational alignment in high precision applications. The damping method includes sensing the angular position of the rotor and utilizing the position signal to generate an error signal in response to changes in the period of rotation of the rotor. The error signal is coupled to phase shift amplifiers which shift the phase of the motor drive signal in a direction to damp out the oscillations in the rotor load angle.

Abstract: This disclosure relates to a system for stabilizing a permanent magnet synchronous motor that does not have a rotor starting cage or windings. The system includes a dc source, an inverter connected to the dc source for converting the dc to a multi-phase ac, and an ac synchronous motor connected to receive the multi-phase ac, the motor being constructed without a starting cage or winding. The system further includes means for sensing variations in the motor power angle, and a control circuit connected to respond to the variations and to cause the inverter output to vary such as to generate an ac component of torque that leads in phase the power angle variations at the natural frequency of the rotor of the motor. The inverter output may be varied by modulating the applied frequency, the dc bus current to the inverter, or the inverter phase angle.

Abstract: A method and apparatus for automatically adjusting an operation time of a servosystem into a predetermined allowable range, either from the outside or from the inside. An average operation time of the servosystem is calculated and then an amount of level shift is calculated from the resulting average operation time. Based on the resulting level shift, the operation time of the servosystem is stepwisely shifted at a given time interval. After the shift, an average operation time of the servosystem is calculated again. This is repeated until the average operation time enters the allowable range.

Abstract: A method and apparatus for controlling the rotational speed and phase of a synchronous motor is provided by sensing the motion of the poles with respect to the stator to provide sensor signals. The sensor signals are converted to sensor pulses and compared to constant pulses. Driving pulses are generated so that if the poles run ahead, a braking moment is generated, and if the poles lag behind, an accelerating moment is generated.

Abstract: A gyro motor supply provides an alternating signal to a gyro hysterisis motor. A detector senses the passage of a reference point on the gyro flywheel during each revolution thereof. A logic circuit is driven by the detector output and controls the phase of the alternating signal thereby ensuring a repeatable gyro start-up condition wherein the phasing is fixed between the reference point on the flywheel and a vector of the rotating field of the motor.

Abstract: For forming an electric voltage signal which is proportional to a flux component of a rotating-field machine, a voltage associated with the flux component is fed to the input of an integrator, and a voltage signal proportional to the flux component is taken off of the integrator. The input of a zero-controller for suppressing the DC component of this voltage signal is connected to the output of the integrator and the output of the zero-controller is connected to a summing point at the input of the integrator. This integrator circuit can be used to determine the position of the flux of a rotating field machine, with the correct phase and amplitude, and independently of frequency, while the zero-controller remains engaged at speeds from the beginning of localization of standing rotor position up to the nominal frequency of the machine. The zero-controller has a P-controller and an I-controller whose output signals are fed to the summing point.

Abstract: A stepping motor driver is adjusted to minimize resonance by adjusting a variable frequency source to adjust the fundamental frequency of the drive to the frequency of a filter, driving the driver and motor with the adjusted frequency source, sensing the motion of the motor and providing the sensed motion to an indicator through the filter. The driver is adjusted to minimize the indication. Adjustment at various harmonics are performed by using 1/N the adjusted frequency, where N is the harmonic of interest.The improved driver includes a plurality of voltage sources adjustable for resonance compensation at the fundamental frequency and 1/N thereof. DC offset, relative gain and orthogonality of the motor driver signal adjustments are provided.

Abstract: A circuit arrangement, for deriving, from sensed power variations in a network, a signal for supplying the exciter of at least one synchronous machine coupled to the network, includes first and second vector identifiers, each providing a direct and phase-shifted output with each of the outputs coupled through an impedance matching amplifier to a summing junction. The direct signal from the first vector identifier and phase-shifted signal from the second vector identifier are conducted to one summing junction and the phase-shifted output of the first vector identifier and direct output of the second vector identifier to a second summing junction, with the outputs of the two summing junctions summed at a further summing junction after being coupled through additional impedance matching amplifiers to result in a total signal at the output of the third summing junction which varies in a mathematically positive sense with increasing oscillation frequency.

Abstract: A system for controlling the amplitude of a drive signal applied to a stepping motor in a manner minimizing the effects of resonance on the resultant angular velocity of the motor shaft. Means are provided for comparing a desired motor drive frequency against one or more known resonant frequencies and, responsive to such comparison, for producing a motor drive signal at an amplitude predetermined to minimize oscillatory fluctuations in the motor shaft velocity.

Abstract: A servo control system for maintaining a direct current motor in operation at a constant speed is provided with two velocity feedback control loops. One feedback control loop is a rate damping loop which responds quickly to minor variations in motor speed to hold the motor at a predetermined command speed. The other loop is a steady state error loop through which a command speed is fed and which responds much more slowly to variations in command speed. The utilization of dual velocity control loops allows the servo system to adjust motor speed quickly in response to deviations in actual motor speed from commanded speed, yet is sensitive to low frequency variations in velocity feedback such as result from disturbances in motor loading.