Motor speed control system using controlled rectifiers

Claim 2

A motor control system wherein a first controlled rectifier is repeatedly fired to permit current flow from a source through the motor armature comprising: a second controlled rectifier and commutating capacitor coupled to said first controlled rectifier, means for controlled firing of said first and second controlled rectifiers, and switch means operable in response to means for generating a control signal, said control signal for synchronously applying current flow to said commutating capacitor and said second controlled rectifier and for subsequently positively terminating current flow through said capacitor and said second controlled rectifier.

Claim 3

A motor control system wherein a first controlled rectifier is repeatedly fired to permit current flow from a source through the motor armature comprising: a second controlled rectifier and commutating capacitor coupled to said first controlled rectifier, means for controlled firing of said first and second controlled rectifiers, and switch means operable in response to means for generating a control signal, said control signal for synchronously applying current flow to said commutating capacitor and said second controlled rectifier and for subsequently positively terminating current flow through said capacitor and said second controlled rectifier.

Claim 4

A motor control system wherein a first controlled rectifier is repeatedly fired to permit current flow from a source through the motor armature comprising: a second controlled rectifier and commutating capacitor coupled to said first controlled rectifier, means for controlled firing of said first and second controlled rectifiers, and switch means operable in response to means for generating a control signal, said control signal for synchronously applying current flow to said commutating capacitor and said second controlled rectifier and for subsequently positively terminating current flow through said capacitor and said second controlled rectifier.

Claim 5

The motor control system of claim 1 wherein said switch means comprises an electronic device having a control electrode for control of current flow through said devices.

Claim 6

The motor control system of claim 1 wherein said switch means comprises a transistor.

Claim 7

The motor control system of claim 1 and further comprising: circuit means responsive to the setting of a speed selection device for generating a pulse train having a frequency and pulse width proportional to the selected speed, pulse width generator circuitry for varying the width of said pulses for speeds exceeding a selected threshold, and means connecting the output of said generator circuitry for control of the operation of said controlled rectifiers and said switch means.

Claim 8

The motor control system of claim 1 and further comprising: torque limiting means for sensing current flow to said control system, means for comparing the sensed current flow to a preset reference value, and means responsive to said comparing means for decreasing the repetition rate and width of current pulses to the motor.

Claim 9

The motor control system of claim 5 and further comprising: means for increasing said reference value in response to increasing pulse duty cycles.

Claim 10

A DC motor control system comprising: a first controlled rectifier connected in series between a DC voltage source and said motor, a second controlled rectifier connected at one terminal to the like terminal of said first controlled rectifier, a capacitor connected between the second like terminals of said first and second controlled rectifiers, means for selectively firing said first and second controlled rectifiers by the application of control signals to the gates thereof, and switch means including at least one transistor having a control terminal, said switch means being connected between said DC voltage source and said second terminal of said second controlled rectifier and operable in response to the application of control signals to said control terminal for controlling the flow of current to said second controlled rectifier and capacitor and thereby preventing lockup of the motor control system.

Claim 11

A DC motor control system comprising: a first controlled rectifier connected in series between a DC voltage source and said motor, a second controlled rectifier connected at one terminal to the like terminal of said first controlled rectifier, a capacitor connected between the second like terminals of said first and second controlled rectifiers, means for selectively firing said first and second controlled rectifiers by the application of control signals to the gates thereof, and switch means including at least one transistor having a control terminal, said switch means being connected between said DC voltage source and said second terminal of said second controlled rectifier and operable in response to the application of control signals to said control terminal for controlling the flow of current to said second controlled rectifier and capacitor and thereby preventing lockup of the motor control system.

Claim 12

The motor control system of claim 7 wherein said first controlled rectifier and said switch means are energized to provide a power cycle to the motor.

Claim 13

The motor control system of claim 8 wherein said switch Means is deenergized and said second controlled rectifier is energized for termination of the motor power cycle.

Claim 14

A motor control system wherein a first controlled rectifier is repeatedly fired to permit current flow from a source through the motor armature comprising: a second controlled rectifier and commutating capacitor coupled to said first controlled rectifier, means for controlled firing of said second controlled rectifier, switch means operable in response to a control signal for synchronously applying and terminating current flow to said commutating capacitor and said second controlled rectifier, circuit means responsive to the setting of a speed selection device for generating a pulse train having a frequency and pulse width proportional to the selected speed, pulse width generator circuitry for varying the width of said pulses for speeds exceeding a selected threshold, said circuitry comprising: a variable period multivibrator, and circuit means for maintaining the period of said multivibrator at a predetermined minimum value for speeds under said selected threshold and for increasing the period of said multivibrator in response to increasing speeds over said selected threshold, and means connecting the output of said generator circuitry for control of the operation of said controlled rectifiers and said switch means.

Claim 15

A motor control system wherein a first controlled rectifier is repeatedly fired to permit current flow from a source through the motor armature comprising: a second controlled rectifier and commutating capacitor coupled to said first controlled rectifier, means for controlled firing of said second controlled rectifier, switch means operable in response to a control signal for synchronously applying and terminating current flow to said commutating capacitor and said second controlled rectifier, circuit means responsive to the setting of a speed selection device for generating a pulse train having a frequency and pulse width proportional to the selected speed, pulse width generator circuitry for varying the width of said pulses for speeds exceeding a selected threshold, said circuitry comprising: a variable period multivibrator, and circuit means for maintaining the period of said multivibrator at a predetermined minimum value for speeds under said selected threshold and for increasing the period of said multivibrator in response to increasing speeds over said selected threshold, and means connecting the output of said generator circuitry for control of the operation of said controlled rectifiers and said switch means.

Claim 16

A DC motor control system comprising: a first controlled rectifier connected in series between a DC voltage source and said motor, a second controlled rectifier connected at one terminal to the like terminal of said first controlled rectifier, a capacitor connected between the second like terminals of said first and second controlled rectifiers, means for selectively firing said first and second controlled rectifiers by the application of control signals to the gates thereof, switch means connected between said DC voltage source and said second terminal of said second controlled rectifier and operable in response to the application of control signals for applying and terminating the flow of current to said second controlled rectifier and capacitor, means responsive to a speed selection device for generating a pulse train having a frequency and pulse width proportional to the selected speed, pulse width generator circuitry for varying the width of said pulses for speeds over a selected threshold, and means connecting the output of said generator circuitry for control of the operation of said controlled rectifiers and said switch means.

Claim 17

A DC motor control system comprising: a first controlled rectifier connected in series between a DC voltage source and said motor, a second controlled rectifier connected at one terminal to the like terminal of said first controlled rectifier, a capacitor connected between the second like terminals of said first and second controlled rectifiers, means for selectively firing said first and second controlled rectifiers by the application of control signals to the gates thereof, switch means connected between said DC voltage source and said second terminal of said second controlled rectifier and operable in response to the application of control signals for applying and terminating the flow of current to said second controlled rectifier and capacitor, means responsive to a speed selection device for generating a pulse train having a frequency and pulse width proportional to the selected speed, pulse width generator circuitry for varying the width of said pulses for speeds over a selected threshold, and means connecting the output of said generator circuitry for control of the operation of said controlled rectifiers and said switch means.

Claim 18

A DC motor control system comprising: means for supplying current pulses to the motor for operation thereof, means for modulating the frequency of said pulses for control of the speed of the motor for duty cycles below a predetermined threshold, and means for modulating the width of said pulses for control of the speed of the motor for duty cycles over said predetermined threshold.

Claim 19

A DC motor control system comprising: means for supplying current pulses to the motor for operation thereof, means for modulating the frequency of said pulses for control of the speed of the motor for duty cycles below a predetermined threshold, and means for modulating the width of said pulses for control of the speed of the motor for duty cycles over said predetermined threshold.

Claim 20

The system of claim 12 wherein said width modulating means comprises: a variable pulse width multivibrator, and means for generating control signals for said multivibrator which vary the pulse width operation thereof for duty cycles over said predetermined threshold.