Dc electric motor control systems

Claim 2

An electric motor speed control system having increased torque at its upper speed range, comprising, in combination: an electric motor having an armature circuit and a field winding circuit; first means for applying a variable-magnitude input voltage to said armature circuit to control the speed of said motor; second means for deriving a direct second voltage commensurate in magnitude with said input voltage; third means for deriving a direct feedback voltage proportional to the instantaneous speed of said motor; and summing circuit means responsive to said second voltage and said feedback voltage for providing a further voltage proportional to the difference between said second voltage and said feedback voltage to control said field winding circuit of said motor, said summing circuit means including a summing circuit and a direct-current time-lag circuit having a predetermined timeconstant, said second voltage being connected directly to said summing circuit and said feedback voltage being connected to said summing circuit through said time-lag circuit means.

Claim 3

A system according to claim 1 wherein said time-constant of said time-lag circuit exceeds one-tenth second.

Claim 4

A system according to claim 1 having switching means responsive to said input voltage for bypassing said time-lag circuit means to connect said feedback voltage directly to said summing circuit.

Claim 5

An electric motor speed control system having increased torque at its upper speed range, comprising, in combination: an electric motor having an armature circuit and a field winding circuit; means for deriving a command voltage commensurate with a desired speed of said motor; amplifier means responsive to said command voltage and to a feedback voltage proportional to the speed of said motor for providing an input voltage to said armature circuit; second means for deriving a second voltage commensurate with said input voltage; third means for deriving said feedback voltage; and summing circuit means responsive to said second voltage and said feedback voltage for exciting said field winding circuit of said motor in proportion to the difference between said second voltage and said feedback voltage.

Claim 6

An electric motor speed control system having increased torque at its upper speed range, comprising, in combination: an electric motor having an armature circuit and a field winding circuit; means for deriving a command voltage commensurate with a desired speed of said motor; amplifier means responsive to said command voltage and to a feedback voltage proportional to the speed of said motor for providing an input voltage to said armature circuit; second means for deriving a second voltage commensurate with said input voltage; third means for deriving said feedback voltage; and summing circuit means responsive to said second voltage and said feedback voltage for exciting said field winding circuit of said motor in proportion to the difference between said second voltage and said feedback voltage.

Claim 7

A system according to claim 4 having means for modulating a direct supply voltage with a duty cycle commensurate with the output voltage of said amplifier means to provide said input voltage to said armature circuit.

Claim 8

A system according to claim 4 having means responsive to the polarity of output signal of said amplifier means relative to a reference level for connecting a load device in parallel with said armature circuit when said output signal has one polarity and for not connecting said load device when said output signal has the opposite polarity.

Claim 9

A system according to claim 6 in which said load device comprises a first storage battery.

Claim 10

A system according to claim 7 in which said first means includes a second storage battery and in which said system includes means connecting said first storage battery to charge said second storage battery.

Claim 11

A system according to claim 6 in which said load dEvice comprises a dynamo-electric machine.

Claim 12

A system according to claim 6 in which said load device comprises resistor means.

Claim 13

A system according to claim 4 in which said summing circuit means is operative to excite said field winding circuit with a current which varies in proportion to the absolute value of the difference between said second voltage and said feedback voltage.

Claim 14

A system according to claim 11 in which said summing circuit means comprises a first summing device connected to receive said second voltage and said feedback voltage, first and second unidirectional conducting means and polarity-inverting voltage, said first unidirectional conducting means and said polarity-inverting means being connected to receive the output signal of said first summing device, said second unidirectional conducting means being connected to receive the output signal of said polarity-inverting means, and means for applying the output signals from said first and second unidirectional conducting means to excite said field winding circuit.

Claim 15

An electric motor speed control system having increased torque at its upper speed range, comprising, in combination: an electric motor having an armature circuit and a field winding circuit; first means for applying a variable input voltage commensurate with a desired speed to said armature circuit; second means for deriving a second voltage proportional to said input voltage; means for sensing the current through said armature circuit to provide a fourth voltage; means responsive to said input voltage and said fourth voltage for deriving a feedback voltage commensurate with the instantaneous speed of said motor; and summing circuit means responsive to said second voltage and said feedback voltage for exciting said field winding circuit of said motor in proportion to the difference between said second voltage and said feedback voltage.

Claim 16

An electric motor speed control system having increased torque at its upper speed range, comprising, in combination: an electric motor having an armature circuit and a field winding circuit; first means for applying a variable input voltage commensurate with a desired speed to said armature circuit; second means for deriving a second voltage proportional to said input voltage; means for sensing the current through said armature circuit to provide a fourth voltage; means responsive to said input voltage and said fourth voltage for deriving a feedback voltage commensurate with the instantaneous speed of said motor; and summing circuit means responsive to said second voltage and said feedback voltage for exciting said field winding circuit of said motor in proportion to the difference between said second voltage and said feedback voltage.

Claim 17

An electrical motor control system, comprising, in combination: an electric motor having an armature circuit and a field winding circuit; means for deriving a command voltage commensurate with a desired speed of said motor; means for deriving a feedback voltage commensurate with the instantaneous speed of said motor; amplifier means responsive to said command voltage and said feedback voltage for deriving a control voltage commensurate with the difference between said command voltage and said feedback voltage; a first storage battery; means responsive to said control voltage for applying voltage from said first storage battery to said armature circuit with a duty cycle commensurate with said control voltage when said control voltage has one polarity; a second storage battery; switching means responsive to the polarity of said control voltage for connecting said armature circuit to said second storage battery when said control voltage has a polarity opposite to said one polarity; and means connecting said second storage battery to charge said first storage battery.

Claim 18

An electrical motor control system, comprising, in combination: an electric motor having an armature circuit and a field winding circuit; means for deriving a command voltage commensurate with a desired speed of said motor; means for deriving a feedback voltage commensurate with the instantaneous speed of said motor; amplifier means responsive to said command voltage and said feedback voltage for deriving a control voltage commensurate with the difference between said command voltage and said feedback voltage; a first storage battery; means responsive to said control voltage for applying voltage from said first storage battery to said armature circuit with a duty cycle commensurate with said control voltage when said control voltage has one polarity; a second storage battery; switching means responsive to the polarity of said control voltage for connecting said armature circuit to said second storage battery when said control voltage has a polarity opposite to said one polarity; and means connecting said second storage battery to charge said first storage battery.

Claim 19

A system according to claim 14 in which said means connecting said second storage battery to charge said first storage battery comprises means for modulating the voltage of said second storage battery to provide an alternating voltage, means for voltage-amplifying said alternating voltage, and means for rectifying the amplified alternating voltage.

Claim 20

A system according to claim 14 having means responsive to said control voltage and said feedback voltage for exciting said field winding circuit in accordance with the absolute magnitude of the difference between said control voltage and said feedback voltage.

Claim 21

A system according to claim 3 in which said switching means is polarity-sensitive and operative to bypass said time-lag circuit when said input voltage has a selected polarity.

Claim 22

A system according to claim 1 in which said summing circuit comprises direct-coupled amplifier means.

Claim 23

A closed-loop electric motor speed control systeM for continuously controlling the speed of a motor over a speed range between zero speed and a maximum speed, comprising, in combination: an electric motor having an armature circuit and a field winding circuit; means for deriving a variable command voltage having a magnitude commensurate with a desired speed of said motor; first amplifier means connected to receive and algebraically sum said command voltage and a feedback voltage, said first amplifier means being operable to provide an input voltage commensurate with the algebraic sum of said command voltage and a feedback voltage, said first amplifier means being operable to provide an input voltage commensurate with the algebraic sum of said command voltage and said feedback voltage to said armature circuit when and only when said algebraic sum has a predetermined sign; second means for deriving said feedback voltage, said feedback voltage varying in proportion to the speed of said motor over said speed range; second amplifier means connected to receive and algebraically sum said feedback voltage and a voltage commensurate with said input voltage to provide an output voltage commensurate with the absolute magnitude of the algebraic sum of the voltages received by said second amplifier means, said output voltage being connected to excite said filed winding circuit of said motor.

Claim 24

A closed-loop electric motor speed control systeM for continuously controlling the speed of a motor over a speed range between zero speed and a maximum speed, comprising, in combination: an electric motor having an armature circuit and a field winding circuit; means for deriving a variable command voltage having a magnitude commensurate with a desired speed of said motor; first amplifier means connected to receive and algebraically sum said command voltage and a feedback voltage, said first amplifier means being operable to provide an input voltage commensurate with the algebraic sum of said command voltage and a feedback voltage, said first amplifier means being operable to provide an input voltage commensurate with the algebraic sum of said command voltage and said feedback voltage to said armature circuit when and only when said algebraic sum has a predetermined sign; second means for deriving said feedback voltage, said feedback voltage varying in proportion to the speed of said motor over said speed range; second amplifier means connected to receive and algebraically sum said feedback voltage and a voltage commensurate with said input voltage to provide an output voltage commensurate with the absolute magnitude of the algebraic sum of the voltages received by said second amplifier means, said output voltage being connected to excite said filed winding circuit of said motor.

Claim 25

A system according to claim 19 having switching means responsive to said input voltage for connecting a load device in parallel with said armature circuit when the algebraic sum of said command voltage and said feedback voltage has a sign opposite to said predetermined sign.