Single-phase motor controls using unitary signal-controlled bi-directional semiconductor gate devices

Claim 2

A control circuit for a single-phase electric motor of the split-phase or capacitor-start kinds, including a main winding and a starting winding angularly displaced from each other in a stator core and inductively coupled to a rotor, comprising: power circuit means for connecting said main winding to a single-phase power supply; sensing means, coupled to said power circuit means, for developing a control signal proportional to the load current to the main winding of the motor; starting circuit means, for connecting said starting winding to the power supply; a unitary signal-controlled bidirectionally conductive semiconductor gate device, having input and output electrodes connected in series in said starting circuit means, and having a gate electrode directly conductively connected to said sensing means, without substantial impedance, for closing said starting circuit means in response to said control signal whenever the load current to said main winding exceeds a first threshold amplitude and for opening said starting circuit means whenever the motor load current falls below a second threshold amplitude; and said sensing means comprising an air core inductance coil connected in series in said power circuit means and having its terminals connected to the input and gate electrodes, respectively, of said gate device.

Claim 3

A control circuit for a single-phase electric motor according to claim 1, and further comprising a magnetic core adjustably movable into and out of said inductance coil to vary said threshold amplitudes.

Claim 4

A control circuit for a single-phase electric motor of the split-phase or capacitor-start kinds, including a main winding and a starting winding angularly displaced from each other in a stator core and inductively coupled to a rotor, comprising: power circuit means for connecting said main winding to a single-phase power supply; sensing means, coupled to said power circuit means, for developing a control signal proportional to the load current to the main winding of the motor; starting circuit means, for connecting said starting winding to the power supply; a unitary signal-controlled bidirectionally conductive semiconductor gate device, having input and output electrodes connected in series in said starting circuit means, and having a gate electrode directly conductively connected to said sensing means, without substantial impedance, for closing said starting circuit means in response to said control signal whenever the load current to said main winding exceeds a first threshold amplitude and for opening said starting circuit means whenever the motor load current falls below a second threshold amplitude; and a pair of Zener diodes connected back to back in series with said gate electrode to determine said threshold amplitudes independently of the operating characteristics of said gate device.

Claim 5

A control circuit for a single-phase electric motor of the split-phase or capacitor-start kinds, including a main winding and a starting winding angularly displaced from each other in a stator core and inductively coupled to a rotor, comprising: power circuit means for connecting said main winding to a single-phase power supply; sensing means, coupled to said power circuit means, for developing a control signal proportional to the load current to the main winding of the motor; starting circuit means, for connecting said starting winding to the power supply; a unitary signal-controlled bidirectionally conductive semiconductor gate device, having input and output electrodes connected in series in said starting circuit means, and having a gate electrode directly conductively connected to said sensing means, without substantial impedance, for closing said starting circuit means in response to said control signal whenever the load current to said main winding exceeds a first threshold amplitude and for opening said starting circuit means whenever the motor load current falls below a second threshold amplitude; and a pair of Zener diodes connected back to back in series with said gate electrode to determine said threshold amplitudes independently of the operating characteristics of said gate device.

Claim 6

A control circuit for a single-phase electric motor of the split-phase or capacitor-start kinds, including a main winding and a starting winding angularly displaced from each other in a stator core and inductively coupled to a rotor, comprising: power circuit means for connecting said main winding to a single-phase power supply; sensing means, coupled to said power circuit means, for developing a control signal proportional to the load current to the main winding of the motor; starting circuit means, for connecting said starting winding to the power supply; a unitary signal-controlled bidirectionally conductive semiconductor gate device, having input and output electrodes connected in series in said starting circuit means, and having a gate electrode directly conductively connected to said sensing means, without substantial impedance, for closing said starting circuit means in response to said control signal whenever the load current to said main winding exceeds a first threshold amplitude and for opening said starting circuit means whenever the motor load current falls below a second threshold amplitude; said sensing means comprising an air core transformer including a primary winding connected in series in one line of said power circuit and a secondary winding having one terminal connected to said input electrode and to said one line of said power circuit and having another terminal connected to said gate electrode; and a magnetic core adjustably movable into and out of said transformer to vary said threshold amplitudes.

Claim 7

A control circuit for a single-phase electric motor of the split-phase or capacitor-start kinds, including a main winding and a starting winding angularly displaced from each other in a stator core and inductively coupled to a rotor, comprising: power circuit means for connecting said main winding to a single-phase power supply; sensing means, coupled to said power circuit means, for developing a control signal proportional to the load current to the main winding of the motor; starting circuit means, for connecting said starting winding to the power supply; a unitary signal-controlled bidirectionally conductive semiconductor gate device, having input and output electrodes connected in series in said starting circuit means, and having a gate electrode directly conductively connected to said sensing means, without substantial impedance, for closing said starting circuit means in response to said control signal whenever the load current to said main winding exceeds a first threshold amplitude and for opening said starting circuit means whenever the motor load current falls below a second threshold amplitude; said sensing means comprising an air core transformer including a primary winding connected in series in one line of said power circuit and a secondary winding having one terminal connected to said input electrode and to said one line of said power circuit and having another terminal connected to said gate electrode; and a magnetic core adjustably movable into and out of said transformer to vary said threshold amplitudes.

Claim 8

A control circuit for a single-pHase electric motor of the split-phase or capacitor-start kinds, including a main winding and a starting winding angularly displaced from each other in a stator core and inductively coupled to a rotor, comprising: power circuit means for connecting said main winding to a single-phase power supply; sensing means, coupled to said power circuit means, for developing a control signal proportional to the load current to the main winding of the motor; starting circuit means, for connecting said starting winding to the power supply; a pair of unitary signal-controlled bidirectionally conductive semiconductor gate devices, each having input and output electrodes connected in series in said starting circuit means, and each having a gate electrode directly conductively connected to said sensing means, without substantial impedance, for closing said starting circuit means in response to said control signal whenever the load current to said main winding exceeds a first threshold amplitude and for opening said starting circuit means whenever the motor load current falls below a second threshold amplitude; said sensing means comprising an air core transformer including a primary winding connected in series in one line of said power circuit and a secondary winding connected at its opposite ends to the respective gate electrodes of said gate devices; and a magnetic core adjustably movable into and out of said transformer to vary said threshold amplitudes.

Claim 9

A control circuit for a single-pHase electric motor of the split-phase or capacitor-start kinds, including a main winding and a starting winding angularly displaced from each other in a stator core and inductively coupled to a rotor, comprising: power circuit means for connecting said main winding to a single-phase power supply; sensing means, coupled to said power circuit means, for developing a control signal proportional to the load current to the main winding of the motor; starting circuit means, for connecting said starting winding to the power supply; a pair of unitary signal-controlled bidirectionally conductive semiconductor gate devices, each having input and output electrodes connected in series in said starting circuit means, and each having a gate electrode directly conductively connected to said sensing means, without substantial impedance, for closing said starting circuit means in response to said control signal whenever the load current to said main winding exceeds a first threshold amplitude and for opening said starting circuit means whenever the motor load current falls below a second threshold amplitude; said sensing means comprising an air core transformer including a primary winding connected in series in one line of said power circuit and a secondary winding connected at its opposite ends to the respective gate electrodes of said gate devices; and a magnetic core adjustably movable into and out of said transformer to vary said threshold amplitudes.

Claim 10

A control circuit for a single-phase electric motor according to claim 5 in which said gate devices are connected in parallel with each other for use with a large low-voltage motor.

Claim 11

A control circuit for a single-phase electric motor according to claim 5 in which said gate devices are connected in series with each other for use with a large high-voltage motor.

Claim 12

A control circuit for a single-phase electric motor of the split-phase or capacitor-start kinds, including a main winding and a starting winding angularly displaced from each other in a stator core and inductively coupled to a rotor, comprising: power circuit means for connecting said main winding to a single-phase power supply; sensing means, coupled to said power circuit means, for developing a control signal proportional to the load current to the main winding of the motor; starting circuit means, for connecting said starting winding to the power supply; a pair of unitary signal-controlled bidirectionally conductive semiconductor gate devices, each having input and output electrodes connected in series in said starting circuit means, said devices being in series with each other, and each having a gate electrode directly conductively connected to said sensing means, without substantial impedance, for closing said starting circuit means in response to said control signal whenever the load current to said main winding exceeds a first threshold amplitude and for opening said starting circuit means whenever the motor load current falls below a second threshold amplitude; said sensing means comprising an air core transformer including a primary winding connected in series in one line of said power circuit and two secondary windings, each secondary winding having one terminal connected to the input electrode and the opposite terminal connected to the gate electrode of a respective one of said gate devices; and a magnetic core adjustably movable into and out of said transformer to vary said threshold amplitudes.

Claim 13

A control circuit for a single-phase electric motor of the split-phase or capacitor-start kinds, including a main winding and a starting winding angularly displaced from each other in a stator core and inductively coupled to a rotor, comprising: power circuit means for connecting said main winding to a single-phase power supply; sensing means, coupled to said power circuit means, for developing a control signal proportional to the load current to the main winding of the motor; starting circuit means, for connecting said starting winding to the power supply; a pair of unitary signal-controlled bidirectionally conductive semiconductor gate devices, each having input and output electrodes connected in series in said starting circuit means, said devices being in series with each other, and each having a gate electrode directly conductively connected to said sensing means, without substantial impedance, for closing said starting circuit means in response to said control signal whenever the load current to said main winding exceeds a first threshold amplitude and for opening said starting circuit means whenever the motor load current falls below a second threshold amplitude; said sensing means comprising an air core transformer including a primary winding connected in series in one line of said power circuit and two secondary windings, each secondary winding having one terminal connected to the input electrode and the opposite terminal connected to the gate electrode of a respective one of said gate devices; and a magnetic core adjustably movable into and out of said transformer to vary said threshold amplitudes.

Claim 14

A control circuit for a single-phase electric motor of the split-phase or capacitor-start kinds, including a main winding and a starting winding angularly displaced from each other in a stator core and inductively coupled to a rotor, comprising: power circuit means for connecting said main winding to a single-phase power supply; sensing means, coupled to said power circuit means, for developing a control signal proportional to the load current to the main winding of the motor; staRting circuit means, for connecting said starting winding to the power supply; a unitary signal-controlled bidirectionally conductive semiconductor gate device, having input and output electrodes connected in series in said starting circuit means, and having a gate electrode directly conductively connected to said sensing means, without substantial impedance, for closing said starting circuit means in response to said control signal whenever the load current to said main winding exceeds a first threshold amplitude and for opening said starting circuit means whenever the motor load current falls below a second threshold amplitude; and said sensing means comprising a resistor having two end terminals connected to said gate device input electrode and to said main winding, respectively, and having a movable tap terminal connected to said gate electrode.

Claim 15

A control circuit for a single-phase electric motor of the split-phase or capacitor-start kinds, including a main winding and a starting winding angularly displaced from each other in a stator core and inductively coupled to a rotor, comprising: power circuit means for connecting said main winding to a single-phase power supply; sensing means, coupled to said power circuit means, for developing a control signal proportional to the load current to the main winding of the motor; staRting circuit means, for connecting said starting winding to the power supply; a unitary signal-controlled bidirectionally conductive semiconductor gate device, having input and output electrodes connected in series in said starting circuit means, and having a gate electrode directly conductively connected to said sensing means, without substantial impedance, for closing said starting circuit means in response to said control signal whenever the load current to said main winding exceeds a first threshold amplitude and for opening said starting circuit means whenever the motor load current falls below a second threshold amplitude; and said sensing means comprising a resistor having two end terminals connected to said gate device input electrode and to said main winding, respectively, and having a movable tap terminal connected to said gate electrode.

Claim 16

A control circuit for a single-phase electric motor according to claim 9 in which said resistor has a low-temperature coefficient of resistivity.

Claim 17

A control circuit for a single-phase electric motor of the split-phase or capacitor-start kinds, including a main winding and a starting winding angularly displaced from each other in a stator core and inductively coupled to a rotor, comprising: power circuit means for connecting said main winding to a single-phase power supply; sensing means, coupled to said power circuit means, for developing a control signal proportional to the load current to the main winding of the motor; starting circuit means, for connecting said starting winding to the power supply; a unitary signal-controlled bidirectionally conductive semiconductor gate device, having input and output electrodes connected in series in said starting circuit means, and having a gate electrode directly conductively connected to said sensing means, without substantial impedance, for closing said starting circuit means in response to said control signal whenever the load current to said main winding exceeds a first threshold amplitude and for opening said starting circuit means whenever the motor load current falls below a second threshold amplitude; and said sensing means consisting essentially of a resistance connected in series with said power circuit means and said main winding, the value of said resistance being selected to establish said threshold amplitudes.

Claim 18

A control circuit for a single-phase electric motor of the split-phase or capacitor-start kinds, including a main winding and a starting winding angularly displaced from each other in a stator core and inductively coupled to a rotor, comprising: power circuit means for connecting said main winding to a single-phase power supply; sensing means, coupled to said power circuit means, for developing a control signal proportional to the load current to the main winding of the motor; starting circuit means, for connecting said starting winding to the power supply; a unitary signal-controlled bidirectionally conductive semiconductor gate device, having input and output electrodes connected in series in said starting circuit means, and having a gate electrode directly conductively connected to said sensing means, without substantial impedance, for closing said starting circuit means in response to said control signal whenever the load current to said main winding exceeds a first threshold amplitude and for opening said starting circuit means whenever the motor load current falls below a second threshold amplitude; and said sensing means consisting essentially of a resistance connected in series with said power circuit means and said main winding, the value of said resistance being selected to establish said threshold amplitudes.

Claim 19

A control circuit for a single-phase electric motor according to claim 11 in which said resistance comprises a single effective loop of resistance material bridged by an adjustable conductive connector, and the terminal of said resistance connected to said gate electrode is also connected to said main winding.

Claim 20

A control circuit for a single-phase electric motor according to claim 11 in which said resistance comprises a resistor element having a tap terminal adjustably movable therealong, and said tap terminal is connected both to said gate electrode and to said main winding.

Claim 21

A control circuit for a single-phase electric motor according to claim 13 in which said resistance is of tapered construction from the low-impedance end to the high-impedance end thereof.

Claim 22

A control circuit for a single-phase electric motor according to claim 10 in which said resistance is formed from a material having a low-temperature coefficient of resistivity.