Control system for a reluctance type motor

Claim 2

A control system including a polyphase alternating current reluctance motor which produces torque in accordance with applied load with the rotor of said motor at any angular position through its speed range from zero angular velocity to a rated running speed, said system also including a variable magnitude, variable frequency voltage generating means which in response to an excitation flux producing signaL and to a desired torque signal, which signifies the torque it is desired that the motor produce, applies an individual voltage to each phase winding of the motor stator to generate an excitation flux for said motor and to control it to produce said desired torque.

Claim 3

A control system according to claim 1, including transducing apparatus which operates in response to said desired torque signal and a signal signifying the instantaneous speed of the motor rotor to produce signals which are applied to the voltage generating means and control the magnitude, phase and frequency of the individual voltages applied to said stator phase windings.

Claim 4

A control system according to claim 2 wherein said transducing apparatus operates in response to said desired torque signal and said instantaneous speed signal to produce a pair of signals, the magnitude of each of said signals varying in accordance with the desired torque and the instantaneous speed of the rotor throughout its speed range, said apparatus utilizing said pair of signals to produce the signals signifying the individual voltages to be applied to said stator windings.

Claim 5

A control system according to claim 3, wherein said transducing apparatus includes a first summing amplifier and a multiplier, both receiving said desired torque signal and said instantaneous speed signal and each producing one of said pair of signals, the summing amplifier producing a signal signifying the sum of the magnitudes of the two signals it receives and the multiplier producing a signal signifying the product of the two signals it receives.

Claim 6

A control system according to claim 4 wherein said transducing apparatus includes a second summing amplifier which receives both the output signal from said multiplier and said excitation flux producing signal and produces an output characteristic of the sum of the magnitudes of the two signals it receives, said excitation flux producing signal being a bias signal which causes said voltage generating means to apply voltages to said stator windings which produce the rated excitation flux of said motor while it is at zero angular velocity so as to enable it to produce the maximum desired torque at that velocity.

Claim 7

A control system according to claim 5, wherein said transducing apparatus includes a rotor position transducer including a cylindrical stator yoke of magnetic material, a two pole permanent magnet rotor mounted for rotation in said cylindrical stator yoke and producing a sinusoidal flux distribution therethrough, said two pole permanent magnet rotor being mechanically connected to the rotor of said motor for rotation therewith and a plurality of Hall effect elements, two such elements for each phase winding of said motor, said elements being mounted at intervals around the interior surface of said yoke so that the physical location of a different first one of such elements corresponds with the physical location of the axis of a different one of the individual phase windings of a stator pole of said motor and a different second such element is in quadrature with each such first element.

Claim 8

A system according to claim 6 wherein the two pole permanent magnet rotor of said rotor position transducer is geared to the rotor of said motor so that one of the poles of said transducer rotor passes the second Hall effect element which is in quadrature with the first element corresponding to one of the phase windings of a stator pole of said motor each time one of the poles of the motor rotor passes the physical location of the axis of the corresponding stator pole phase winding.

Claim 9

A system according to claim 7, wherein each said first Hall effect element receives the output signal of said first summing amplifier and produces a signal signifying that component of the individual voltage for its associated phase winding which balances the counterelectromotive force which would be produced across said phase winding at no load at the speed at which the rotor is then rotating by the flux generated by the excitation current then flowing in each winding as well as the leakage reactance drop across each winding by the excitation current then flowing in the winding and the resistance voltage drop produced across said phase winding by the load current it is then conducting.

Claim 10

A system according to claim 8, wherein each said second Hall effect element receives the output signal of said second summing amplifier and produces a signal signifying both that component of the individual voltage for its associated phase winding which balances the leakage reactance voltage drop produced across said phase winding by the load current it is then conducting at the speed at which the rotor is then rotating as well as the counterelectromotive force produced at that speed in said phase winding by the flux generated by the load current then flowing in the winding and that component which produces the rated excitation flux of said motor while it is at zero angular velocity so as to enable it to produce the maximum desired torque.

Claim 11

A system according to claim 9, wherein said transducing apparatus includes signal summing amplifier circuitry for each phase winding of said motor, each said signal summing amplifier circuitry receiving the signal produced by the first and second Hall effect elements associated with its respective phase winding and producing an output signal signifying the vector sum of said signals.

Claim 12

A control system according to claim 10, including speed dictation apparatus generating a signal signifying a desired speed for said motor, a speed responsive generator generating a signal signifying the actual speed of said motor, and a summation circuit responsive to said desired and actual speed signals producing said desired torque signal.

Claim 13

A control system for a polyphase reluctance type motor operable to control said motor to produce torque in response to a continuously applied load with the rotor of said motor at any angular position and at any speed from zero angular velocity to a rated operating speed, said system including a first summing amplifier generating a signal whose magnitude is characteristic of the sum of the magnitudes of a signal signifying the instantaneous speed of said motor and a signal signifying the torque it is desired to have said motor produce, a multiplier generating a signal whose magnitude is characteristic of the product of the magnitude of said instantaneous speed signal and said desired torque signal, a second summing amplifier generating a signal whose magnitude is characteristic of the sum of the magnitudes of said multiplier output signal and a bias signal, said bias signal operating to produce the rated excitation flux of said motor while it is at zero angular velocity so as to enable it to produce the maximum desired torque, a rotor position transducer connected to the rotor of said motor for rotation thereby, said transducer receiving said first and second summing amplifier output signals and producing signals signifying the magnitude, frequency and phase of the individual voltages to be applied to each phase winding of said motor to cause it to produce said desired torque and signal translating apparatus receiving said transducer signals and generating said individual voltages.

Claim 14

A control system for a polyphase reluctance type motor operable to control said motor to produce torque in response to a continuously applied load with the rotor of said motor at any angular position and at any speed from zero angular velocity to a rated operating speed, said system including a first summing amplifier generating a signal whose magnitude is characteristic of the sum of the magnitudes of a signal signifying the instantaneous speed of said motor and a signal signifying the torque it is desired to have said motor produce, a multiplier generating a signal whose magnitude is characteristic of the product of the magnitude of said instantaneous speed signal and said desired torque signal, a second summing amplifier generating a signal whose magnitude is characteristic of the sum of the magnitudes of said multiplier output signal and a bias signal, said bias signal operating to produce the rated excitation flux of said motor while it is at zero angular velocity so as to enable it to produce the maximum desired torque, a rotor position transducer connected to the rotor of said motor for rotation thereby, said transducer receiving said first and second summing amplifier output signals and producing signals signifying the magnitude, frequency and phase of the individual voltages to be applied to each phase winding of said motor to cause it to produce said desired torque and signal translating apparatus receiving said transducer signals and generating said individual voltages.

Claim 15

A control system according to claim 12, wherein said rotor position transducer produces a first and second output signal for each phase winding in response to said first and second summing amplifier output signals, respectively, said first transducer output signal for each phase winding signifying that component of the voltage to be applied to its associated phase winding to balance the counterelectromotive force which would be generated at no load in said phase winding at the speed at which the rotor is then rotating by the flux produced by the excitation current then flowing in the winding as well as the leakage reactance drop across the winding produced by that excitation current and the resistance voltage drop therein owing to the load cuRrent then flowing in said phase winding, said second transducer output signal for each phase winding signifying both that component of the voltage to be applied to its associated phase winding to balance the leakage reactance voltage drop across said phase winding owing to the load current then flowing therein and to the speed at which the rotor is then rotating as well as to the counterelectromotive force produced at that speed in said winding by the flux generated by said load current and that component of the voltage applied to its associated phase winding which produces the rated excitation flux of the motor while it is at zero angular velocity so as to enable it to produce the maximum desired torque.

Claim 16

A control system according to claim 13, including speed dictation apparatus generating a signal signifying a desired speed for said motor, a speed responsive generator generating a signal signifying the actual speed of said motor, and a summation circuit responsive to said desired and actual speed signals producing said desired torque signal.