Abstract: A system and method are provided for controlling a stepper motor having a rotor and a multi-phase stator. Sinusoidal command signals define a commanded position of the motor's rotor. An actual position of the rotor is sensed as a function of an electrical angle between the actual position and the commanded position. The actual position is defined by sinusoidal position signals. An adjustment signal is generated using the sinusoidal command signals and sinusoidal position signals. The adjustment signal is defined as a function of the cosine of the electrical angle. The adjustment signal is multiplied by each sinusoidal command signal to generate a corresponding set of excitation signals, each of which is applied to a corresponding phase of the multi-phase stator.

Abstract: An energy storage system for a spacecraft is provided which employs a solar powered flywheel arrangement including a motor-generator which, in different operating modes, drives the flywheel and is driven thereby. A control circuit, including a threshold comparator, senses the output of a solar energy converter, and when a threshold voltage is exceeded thereby indicating the availability of solar power for the spacecraft loads, activates a speed control loop including the motor-generator so as to accelerate the flywheel to a constant speed and thereby store mechanical energy, while also supplying energy from the solar converter to the loads. Under circumstances where solar energy is not available and thus the threshold voltage is not exceeded, the control circuit deactivates the speed control loop and activates a voltage control loop that provides for operation of the motor as a generator so that mechanical energy from the flywheel is converted into electrical energy for supply to the spacecraft loads.

Abstract: A control circuit is provided for a brushless three-phase d.c. motor which affords four quadrant control from a single command. The control circuit provides acceleration of the motor in both clockwise and counterclockwise directions and braking and generation in both clockwise and counterclockwise directions. In addition to turning on individual transistors of the transistor pairs connected to the phase windings of the motor for 120.degree. periods while the other transistor of that pair is off, the control circuit also provides, in a further mode of operation, turning the two transistors of each pair on and off alternately at a phase modulation frequency during such a 120.degree. period. A feedback signal is derived which is proportional to the motor current and which has a polarity consistent with the command signal, such that negative feedback results.

Abstract: A solar powered system wherein a load such as a compressor (16) is driven by a main induction motor (14) powered by a solar array (10), and an auxiliary motor (18) shares the load with the solar powered motor in proportion to the amount of sunlight available, is provided with a power factor controller (20) for controlling voltage applied to the auxiliary motor in accordance with the loading on that motor. In one embodiment, when sufficient power is available from the solar cell array the auxiliary motor is driven as a generator by excess power from the main motor so as to return electrical energy to the power company utility lines.

Abstract: A coupling system for an induction motor type generator (10) to an A.C. power line (18) wherein an electronic switch means (28) which is controlled by a control system (30) is regulated to turn "on" at a relatively late point in each half cycle of its operation whereby the energizing power supplied by the line (18) to the induction motor type generator (10) is decreased and the net power delivered to the line is increased.

Abstract: A power factor controller for an A.C. induction motor (10) is provided which is of the type comprising thryistor switches (110), (111) and (112) connected in series with the motor, phase detectors (122), (124) and (126) for sensing the motor current and voltage and providing an output proportional to the phase difference between the motor voltage and current, and a control circuit, responsive to the output of the phase detector and to a power factor command signal, for controlling switching of the thyristor. The invention involves sensing the induced emf produced by the motor during the time interval when the thryistor is "off" and for producing a corresponding feedback signal for controlling switching of the thyristor. The sensed emf is also used to enhance "soft" starting of the motor.

Abstract: A phase-detector (16, 18, 20) is provided for use in a power factor controller for a three-phase induction motor. The power factor controller includes switching thyristors (10, 12 14) for each motor phase winding and the phase detector for each phase includes an operational amplifier (36) which senses the current phase angle for that phase by sensing the voltage across the phase thyristor. Common mode rejection is achieved by providing positive feedback between the input and output of the voltage sensing operational amplifier.

Abstract: A motor power control of the type which functions by controlling the power factor wherein one of the parameters of power factor current "on" time is determined by the "on" time of a triac through which current is supplied to the motor, and wherein, by means of a positive feedback circuit, a wider range of control is effected.

Abstract: A power control circuit for a three phase induction motor wherein power factors for the three phases are summed to provide a control signal, and this control signal is particularly filtered and then employed to control the duty cycle of each phase of input power to the motor.

Abstract: A trigger control circuit is provided for producing firing pulses for the thyristor of thyristor control system such as a power factor controller. The control circuit overcomes thyristor triggering problems involved with the current lag associated with controlling inductive loads and utilizes a phase difference signal, already present in the power factor controller, in deriving a signal for inhibiting generation of a firing pulse until no load current is flowing from the preceding half cycle and thereby ensuring that the thyristor is triggered on during each half cycle.

Abstract: A control circuit for an induction motor powered system wherein a power factor controlled servo loop is used to control, via the phase angle of firing of a triac (16), the power input to the motor (14) as a function of load placed on the motor (14) by machinery of the powered system. Then, upon application of torque by this machinery to the motor (14), which tends to overspeed the motor, the firing angle of the triac (16) is automatically set to a fixed, and relatively short, firing angle.

Abstract: A power factor type motor controller in which the conventional power factor constant voltage command signal is replaced during a starting interval with a graduated control voltage. The present invention adds to the three-phase system of pending application Ser. No. 199,765, filed Oct. 23, 1980, means for modifying the operation of the system for a motor start-up interval of 5 to 30 seconds. The modification is that of providing via ramp generator 174 an initial ramp-like signal which replaces a constant power factor signal supplied by potentiometer 70. The ramp-like signal is applied to terminal 40 where it is summed with an operating power factor signal from phase detectors 32, 34, and 36 to thereby obtain a control signal for ultimately controlling SCR devices 12, 14, and 16 to effect a gradual turn-on of motor 10.

Abstract: A failure detector is provided for detecting unidirectional failures in triacs, particularly as used in power factor controllers for induction motors. In a first embodiment, the triac voltage waveform is sensed and upon detection of an unbalanced signal, corresponding to failure of the triac in either the positive or negative direction, the triac is turned full on in both directions. In a second embodiment, a pair of pulsed signals are derived, the pulse durations of which are proportional to the phase difference between the load current and voltage for each half cycle, and the triac is turned full on responsive to a difference in pulse duration between the half cycle signals. An unidirectional open circuit detector is adapted to use a signal from either of the first and second embodiments to turn the triac off in response to an open circuit failure in either direction.

Abstract: A power generating system for adjustably coupling an induction motor, as a generator, to an A.C. power line wherein the motor and power line are connected through a triac. The triac is regulated to normally turn "on" at a relatively late point in each half cycle of its operation, whereby at less than operating speed, and thus when the induction motor functions as a motor rather than as a generator, power consumption from the line is substantially reduced.

Abstract: A power control circuit for an induction motor wherein a servo loop is used to control power input by controlling the power factor of motor operation, and wherein the power factor is measured by summing the voltage and current derived square wave signals.

Abstract: A power factor control system for use with AC induction motors which samples line voltage and current through the motor and decreases power input to the motor proportional to the detected phase displacement between current and voltage to thereby provide less power to the motor, as it is less loaded.

Abstract: A tachometer in which sine and cosine signals responsive to the angular position of a shaft as it rotates are each multiplied by like, sine or cosine, functions of a carrier signal, the products summed, and the resulting frequency signal converted to fixed height, fixed width pulses of a like frequency. These pulses are then integrated, and the resulting DC output is an indication of shaft speed.