General Electric Company

Synektron Corporation

Allan B Plunkett

John D D'Atre

Fred G Turnbull

Robert Louis Steigerwald

Gerald Burt Kliman

Allen Michael Ritter

Luis Jose Garces

Thomas Anthony Lipo

Timothy J Miller

Joseph Phillip Franz

Robert J Griffith

A sensorless control for DC permanent magnet brushless motor includes a feedback loop connected between the motor stator windings and the inverter which controls the timer at which current is provided to the various windings in sequence. The control of the invention includes a voltage sensing network for sensing the back EMF on each motor winding when it is unenergized and comparing this voltage with a null point. For maximum torque this voltage has an optimum value and variation from this value produces an error signal which is integrated to produce a VCO drive signal. This signal controls the frequency of a VCO which in turn controls the switching times of the inverter.

Back EMF sampling circuit for phase locked loop motor control

A field orientation control system for an interior permanent magnet synchronous motor includes function generating means responsive to a torque command signal for producing direct and quadrature axis direct current signals which are converted to synchronously-varying two-phase signals for coupling to power control means, for effecting sinusoidal energization of the permanent magnet motor. The function generators modify the torque command signal as a predetermined function of the motor parameters. Rotor position information is derived from measured stator voltages and currents without the use of a separate rotor position sensor. The control system includes means for establishing a preselected amplitude of a stator .alpha.-axis current in the motor at start-up prior to establishing orthogonal .beta.-axis current such that the motor rotor is caused to become initially aligned with the selected .alpha.-axis.

Field orientation control of a permanent magnet motor

In a converter for a switched reluctance motor, a dump capacitor receives freewheeling current from each phase and resupplies the charge to the dc supply. In this manner, residual magnetic energy is recovered and phase current quickly reduced while the converter requires only one main switching device and one freewheeling device per phase and the converter allows a unipolar source to be used.

Regenerative unipolar converter for switched reluctance motors using one

An electric machine has a stator body formed of a coil of concentric layers of amorphous metal tape and slots are formed in one end of the coil for receiving a stator winding. A rotor structure having permanent magnet poles embedded therein is placed adjacent the end surface of the stator and is coupled thereto through the axial gap between the stator and rotor. The magnets are held in place in a nonmagnetic matrix which consists of an epoxy fiber laminate material. By enlarging the outer diameter of the rotor with the epoxy fiber laminate material, the rotor serves as an integral flywheel structure.

Synchronous disk motor with amorphous metal stator and permanent magnet

A variable speed a-c drive motor is controlled by a current feedback pulse width modulation scheme which effectively isolates the controlled motor current from variations in the input d-c voltage. An additional control loop is provided to superimpose a control signal on the amplitude command input circuit of the pulse width modulation control scheme. The additional loop responds to line current and particularly line current resonance between the input d-c filter and the line inductance. Instantaneous line current is then maintained at the minimum required to support instantaneous power flow to the a-c motor so that resonance current is suppressed.

Control circuit for suppression of line resonances in current feedback

Improved operation of a pulse width modulated inverter machine drive system is obtained by a control apparatus which regulates inverter switching device conduction by modifying switching signal waveforms transmitted to the inverter to eliminate switching pulses narrower than the minimum inverter switching device pulse width. By dropping the narrow inverter switching pulses in sequence during the exact interval which the pulses would otherwise occur and boosting the amplitude of remaining pulses, the control apparatus permits the inverter to smoothly transition from pulse width modulation operation to square wave operation without objectionable jumps in inverter output voltage.

Pulse width modulated inverter machine drive

Apparatus for controlling a permanent magnet AC synchronous motor supplied by a forced commutated inverter that does not use a mechanical shaft position sensor. A control loop regulates an inverter frequency and maintains inverter synchronism with the motor using electrical angle feedback signals developed from measured flux signals that have been phase shifted.

Apparatus for controlling a PWM inverter-permanent magnet synchronous

Alternating current is supplied to an auxiliary load on a transit car from a power supply comprised of a DC-energized inverter and a synchronous machine coupled to the inverter. The inverter supplies the alternating current requirements of the load up to the normal steady state load current magnitude. The synchronous machine stores kinetic energy when the load current load does not exceed its normal steady state magnitude, and converts kinetic energy into electrical energy to supply the load current requirements in excess of its normal steady-state load magnitude and to supply load current whenever the DC source-inverter connection is interrupted. Frequency and amplitude of load voltage are regulated by operator commands through control apparatus coupled to the inverter and the synchronous machine.

Auxiliary power supply with kinetic energy storage

An alternating current machine drive system, comprised of an alternating current machine and an inverter configured of a plurality of pairs of transistors with the transistors of each pair coupled in series-aiding fashion and each of the pairs of serially coupled transistors connected across a direct current source, is controlled in accordance with inverter current. The transistors of each inverter transistor pair are alternately rendered conductive to supply alternating current at the inverter output in accordance with a current error signal, proportional to the difference in magnitude between actual inverter phase current and a sinusoidal reference signal, with the conduction state of the transistors of each pair reversing each time the current error signal exceeds an upper and lower hysteresis limit, which limits vary in accordance with actual inverter phase current. Conditioning of inverter output voltage to control machine speed and torque is achieved by varying the sinusoidal reference signal frequency and amplitude, respectively, in accordance with operator commands. Optimum inverter machine drive performance is achieved by regulating the sinusoidal reference signal amplitude and frequency in accordance with a feedback machine torque signal and a feedback machine flux signal, respectively.

Transistorized current controlled pulse width modulated inverter machine

To achieve synchronization of an inverter-synchronous machine drive system, feedback of a phase angle signal, derived in part from stator current drawn by, and voltage supplied to, the synchronous machine, is provided to control the frequency of inverter thyristor conduction. At light or zero synchronous machine load conditions, machine stator current may be of insufficient magnitude to permit derivation of the phase angle feedback signal; therefore, substitute simulated stator current signals, proportional to a preselected combination of inverter thyristor gating pulses, are utilized to derive the phase angle feedback signal, thereby allowing inverter-synchronous machine drive synchronism to be maintained.

Apparatus for maintaining synchronism of an inverter-synchronous machine

In an inverter-synchronous machine drive system subject to operator control, feedback control is employed to synchronize machine-inverter operation. A phase angle command signal, responsive to a fixed value phase angle signal during initial machine excitation and alternately responsive to machine load variation as controlled by an operator command, is generated and compared against the actual machine phase angle difference between machine phase current and air gap flux. A frequency command signal, responsive to the angle difference therebetween, is impressed on the inverter to vary machine excitation responsive to the magnitude of the phase angle difference.

Method and apparatus for control of inverter synchronous machine drive

A substantially smooth, continuous and sinusoidal air gap flux signal for an AC machine is provided from machine terminal voltages and line currents. A voltage representative of the machine stator voltage is combined with a voltage representative of the resistive voltage drop component across the stator to yield an intermediate voltage. This intermediate voltage is integrated and combined with a voltage representative of the stator flux leakage reactance to yield an air gap flux signal proportional to the difference between the integral of the intermediate voltage and the stator flux leakage reactance voltage.

Method and apparatus for generating an air gap flux signal for an AC

An a-c electric induction motor control system having apparatus for balancing motor air-gap flux against motor stator current in a manner to derive a motor excitation command signal which tends to cause the control system to force the motor to operate on a predetermined torque versus slip frequency characteristic. The motor excitation command signal is utilized to regulate the magnitude of excitation supplied to the motor such that the air-gap flux level assumes a predetermined magnitude as a function of the motor slip frequency. Above motor corner point velocity, the balancing is modified in favor of flux such that the motor is operated in a constant horsepower mode.

Excitation commanding for current fed motor drives

The stator terminals of an adjustable speed a-c induction motor are connected to a source of d-c electric power by means of an inverter, and a system is provided for blending both dynamic and regenerative electrical braking of the motor whenever it decelerates. The brake blending system comprises a plurality of braking resistors respectively coupled by a corresponding switch in parallel with the power source. The switches are controlled by a control circuit which responds to motor terminal voltage, motor angular velocity and the difference between the commanded and actual motor torques to determine the additional current which the motor could regenerate without exceeding commanded parameters. When the additional current corresponds to that current which can be absorbed by adding an additional stage of braking resistance, the control circuit actuates a switch to add a stage of dynamic brake resistance. The control circuit also monitors the voltage of the source and removes braking resistance in steps to maintain source voltage within selected limits in order to maximize the current fed to the power source and thus maximize regenerated energy. In an alternate embodiment the control circuit determines the admittance of the source and utilizes the admittance to maintain source voltage substantially constant by removal of dynamic brake resistance in order to force more regenerative current to the source.

Dynamic brake blending for an inverter propulsion system

Apparatus for electronically simulating the response of a direct current traction motor to predetermined operating states whereby there is provided a resultant signal representative of the torque that would be produced by an actual motor operating in the prescribed states. The apparatus calculates E per RPM for the simulated motor from measured values of available armature voltage and armature velocity. A function generator thereafter converts the E per RPM signal to a signal representative of the motor field current based upon known values for the simulated motor. The field current signal is converted to an armature current signal by a circuit which responds to the motor commanded state of field weakening to compute the instantaneous ratio of armature current to field current under the commanded conditions and thereafter multiplies the field current signal by that ratio to obtain a signal representative of armature current. Multiplication of the armature current signal by the E per RPM signal then yields a signal representative of the torque which would be developed by the simulated motor.

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Scotia, NY, United States of America

Allan B Plunkett