Abstract: A system is provided for sensing a motor current from a three phase inverter. A first resistor is coupled between a first transistor of the inverter and a supply voltage, and a second resistor is coupled between a second transistor of the inverter and ground. Circuitry coupled to the first and second resistors generates an upper and lower current. When the first transistor is active, the upper current is proportional to the sum of a reference voltage and a voltage across the first resistor, and the lower current is proportional to the reference voltage. When the second transistor is active, the upper current is proportional to the reference voltage, and the lower current is proportional to the sum of the reference voltage and a voltage across the second resistor. Based on the difference of the lower and upper currents, the circuitry provides an output current proportional to the motor current.

Abstract: A back EMF controlled, synchronous, permanent magnet motor capable of extremely high rotation speeds at high efficiency. The motor includes a permanent magnet flux source and excitation coils for producing a rotating magnetic field mounted on an iron free form to substantially eliminate core loss and resulting rotor drag. Back EMF is determined directly from the excitation and controls the excitation to produce a torque angle of substantially 90.degree. between the magnet and coil fluxes. Coil excitation is used at maximum efficiency and hunting is avoided. The permanent magnet provides a high flux density that also allows a low current in the motor coils and thus reduces coil copper losses to further improve efficiency.

Abstract: A system for generating substantially constant area pulses suitable for application to an inertial instrument torquer. The torquer current pulses are directly utilized to provide an averaging feedback loop wherein the variations in pulse width due to errors in switching pulse times are offset by amplitude control for the pulses. With this system, variations in width of the torquer current pulses are offset in a high speed, closed loop manner with compensation occurring within the pulse interval.

Abstract: A method of measuring induction motor parameters so that the speed and torque control of an induction motor controller may be optimized. While the motor is stopped, a test signal made up of a current pulse of a known amplitude is applied to one or more windings of the motor stator for a selected period of time, after which the current pulse is turned off. After a short delay, the instanteous voltage across the stator windings is measured, and also an integration of the stator voltage is started which continues long enough so that the stator voltage decays to substantially zero. The measured voltage and integrated voltage are respectively proportional to the rotor resistance and the motor magnetizing inductance.

Abstract: An AC motor drive includes a power converter which supplies current to a DC bus from three-phase power lines. An inverter drives the motor from power delivered to the DC bus and it regenerates power to the DC bus when the motor is decelerated. The power converter in turn regenerates the power to the power lines by controlling line current such that it is substantially in-phase with the applied line voltages. Current overload protection is provided for the transistor switches employed in the power converter bridge circuit.

Abstract: A microprocessor-based motor control system operates the rapid advance motor on a slide transfer machine to carry out rapid traverse motions in minimal time. A velocity profile is stored during the acceleration portion of the move and this data is employed to determine when deceleration should begin and to control velocity during the deceleration portion of the move. A position feedback circuit having programmable resolution is employed to develop the velocity profile.

Abstract: The present invention generates a motor slip frequency value and two current magnitude values representing quadrature components of the motor stator current to be generated. Closed-loop control of the motor operation is provided by feeding back a signal representative of the motor shaft speed or position calculate the torque required from the motor. The feedback signal is separated into high and low frequency components. Additional circuitry changes the value in response to detected variations in the high frequency components of the feedback signal. The addition of this circuitry causes the motor control circuit to no longer represent the inverse of the motor transfer function network.

Abstract: A current sensing circuit includes an impedance network having a capacitor which produces a voltage proportional to the steady-state component of current and an inductance which produces a voltage proportional to the transient component. The capacitor voltage modulates a carrier signal which conveys the steady-state component through an isolation transformer to a demodulator. The transient component is conveyed through a second isolation transformer and is summed with the demodulated steady-state component.

Abstract: A transducerless brushless permanent magnet motor in which a signal induced by the rotor in an unexcited winding is used to sense the rotor position. The sensed voltage, induced in the winding by the rotor, is integrated to provide a representation of the magnetic flux coupling the rotor and winding. Before start-up, both the rotor position and the integrator are initialized to align the circuit representation of the flux with the actual flux.In an additional embodiment of the invention, a self-initialization circuit is provided to automatically preset the rotor and flux integrator to pre-determined and corresponding values.

Abstract: An electric power generator system including a switched capacitor controlled induction generator adapted to provide power at a regulated voltage and frequency. The system is adapted for autonomous operation for delivery of power with unity power factor to an external power grid.

Abstract: A control system for an induction machine. The system includes a multiphase variable frequency oscillator adapted to provide at least one pair of signals having frequencies proportional to the sum of a desired slip frequency and the frequency of rotation of the induction motor shaft, where the signals are in phase quadrature. A weighting network amplitude-scales one of each pair of signals by a factor related to the desired slip frequency. A summing network then generates an excitation signal for each stator winding by summing the amplitude-scaled signal and its associated quadrature signal corresponding to that stator winding.

Abstract: A back EMF controlled, synchronous, permanent magnet motor capable of extremely high rotation speeds at high efficiency. The motor includes a permanent magnet flux source and excitation coils for producing a rotating magnetic field mounted on an iron free form to substantially eliminate core loss and resulting rotor drag. Back EMF is determined directly from the excitation and controls the excitation to produce a torque angle of substantially 90.degree. between the magnet and coil fluxes. Coil excitation is used at maximum efficiency and hunting is avoided. The permanent magnet provides a high flux density that also allows a low current in the motor coils and thus reduces coil copper losses to further improve efficiency.

Abstract: A slip frequency controller for an induction motor. The controller includes an oscillator for providing a high frequency (f.sub.o) pulse stream which is counted down by first counter having modulo M and a second counter with modulo M+K, where M is a positive integer, K is a positive or negative integer, and K is small compared with M. An incremental shaft encoder provides a relatively low frequency pulse stream having a pulse repetition frequency equal to M times the shaft rotation frequency for the motor times the number of pole pairs in the motor. Each pulse produced by the encoder represents an angular increment in position of the motor shaft. The output frequency of the first counter is slightly modified from the nominal f.sub.o /M by a pulse adder/subtracter network which either adds or subtracts a pulse from the input pulse stream applied to the first counter each time a pulse is received from the shaft encoder. The output frequency of the first counter is then f.sub.