Alternating current motor speed control circuit

Claim 2

In a control circuit for generating alternating current pulses at a sub-multiple frequency of an alternating current reference voltage: a full wave rectifying bridge network connectable to the alternating current reference voltage and operable to convert the sinusoidal current waveform of the source to a unidirectional current waveform in which the half cycles thereof are all of one polarity, a controlled rectifier having a gating terminal, sawtooth waveform generator circuit means coupled to the rectifying bridge network to receive the unidirectional current converted thereby and connected to the gating terminal of said controlled rectifier and being operable to generate and deliver successive sawtoothed shaped pulses of like polarity thereto, said waveform generator circuit means including one or more resistances each having a resistive value different from any other such resistance and being capable when coupled into the circuit of the waveform generator means to produce a sawtoothshaped pulse having a time span equal to the duration of three or higher odd numbers of consecutive half cycles of the reference voltage but differing from one another in the number of half cycles in the span thereof and further including means for selectively coupling each such resistance into the waveform generator circuit, and control means responsive to the zero crossings of the reference voltage for controlling the waveform generator circuit means and operable to superimpose voltage spikes on the sawtooth waveforms produced by the waveform generator which extend in the same direction of amplitude as the waveforms and which coincide in time to all of the zero crossings of the reference voltage for timing the start and termination of each such sawtooth waveform, whereby a selected odd numbered sequence of half cycles of the reference voltage may be supplied by the control circuit with an alternating frequency less than that of the referenced voltage.

Claim 3

The aparatus as defined in claim 1 wherein an additional resistance is provided which may be selectively coupled into the sawtooth waveform generator circuit, said resistance having a resistive value such as to produce a sawtooth-shaped pulse having a time span equal to the duration of an even number of consecutive half cycles of the reference voltage whereby when such resistance is coupled into the generator circuit it will cause the latter to supply half cycles of the reference voltage which are all of one poLarity.

Claim 4

A circuit for controlling the operation of an alternating current responsive motor from an alternating current reference voltage comprising: a full wave rectifying bridge network connectable with such a motor and operable to convert the sinusoidal current waveform of the reference voltage to a unidirectional current waveform in which the half cycles thereof are all of one polarity, controlled rectifier means coupled to the rectifying bridge network and having terminal means for gating the same, a wave generator circuit coupled to the rectifying bridge network to receive the unidirectional current converted thereby and connected to the gating terminal means of said controlled rectifier means and including a unijunction transistor and a capacitor coupled to the input of the unijunction transistor, and resistance means comprising one or more resistances and means for selectively coupling the same to the capacitor and to the input of the unijunction transistor, said one or more resistances each having such a resistive value as to cause the generator circuit to produce successive pulses of sawtooth wave-shape having a distinctive duration differing from that of any other such resistance but approximately equivalent to a distinctive odd multiple number of half cycles of the reference voltage, and control means for synchronizing the operation of the wave generator circuit with the reference voltage by producing voltage spikes similar in polarity to the sawtooth waveforms produced by said wave generator circuit and superimposing such voltage spikes on the sawtooth waveforms which extend in the same direction of amplitude as the waveforms and which coincide in time with all of the zero crossings of the reference voltage for timing the start and termination of each sawtooth pulse with zero crossings of the reference voltage, whereby selected odd numbered sequences of half cycles of the reference voltage may be supplied to the motor with an alternating frequency less than that of the reference voltage.

Claim 5

A circuit for controlling the operation of an alternating current responsive motor from an alternating current reference voltage comprising: a full wave rectifying bridge network connectable with such a motor and operable to convert the sinusoidal current waveform of the reference voltage to a unidirectional current waveform in which the half cycles thereof are all of one polarity, controlled rectifier means coupled to the rectifying bridge network and having terminal means for gating the same, a wave generator circuit coupled to the rectifying bridge network to receive the unidirectional current converted thereby and connected to the gating terminal means of said controlled rectifier means and including a unijunction transistor and a capacitor coupled to the input of the unijunction transistor, and resistance means comprising one or more resistances and means for selectively coupling the same to the capacitor and to the input of the unijunction transistor, said one or more resistances each having such a resistive value as to cause the generator circuit to produce successive pulses of sawtooth wave-shape having a distinctive duration differing from that of any other such resistance but approximately equivalent to a distinctive odd multiple number of half cycles of the reference voltage, and control means for synchronizing the operation of the wave generator circuit with the reference voltage by producing voltage spikes similar in polarity to the sawtooth waveforms produced by said wave generator circuit and superimposing such voltage spikes on the sawtooth waveforms which extend in the same direction of amplitude as the waveforms and which coincide in time with all of the zero crossings of the reference voltage for timing the start and termination of each sawtooth pulse with zero crossings of the reference voltage, whereby selected odd numbered sequences of half cycles of the reference voltage may be supplied to the motor with an alternating frequency less than that of the reference voltage.

Claim 6

Wave generating apparatus for controlling the speed of a motor responsive to alternating current powering means, comprising: a full wave rectifying bridge network connectable to such a motor and operable to convert the sinusoidal current waveform of the powering means to a unidirectional current waveform in which the half cycles thereof are all of one polarity. two sets of controlled rectifiers incorporated in said bridge circuit, the rectifiers in each set being disposed in diametrically opposite branches of the bridge circuit and each having a gating terminal, a sawtooth wave generator coupled to the rectifying bridge network to receive the unidirectional current converted thereby and including a unijunction transistor normally biased in a high impedance condition and capacitive means coupled to said unijunction transistor and operative periodically to discharge therethrough when its charge attains the peak-point voltage of the unijunction transistor, a pair of pulse transformers having their secondaries coupled individually to the two sets of controlled rectifiers, a trigger circuit coupled to said pair of pulse transformers and including gating means responsive to successive sawtooth pulses delivered by said unijunction transistor to said pair of transformers for alternately enabling the same for the duration of each of the sawtooth pulses, a control circuit coupled to said capacitive means and to said unijunction transistor and including means responsive to the alternating current powering means for producing relatively low voltage signals coinciding in time with the zero crossings of the alternating current and further including means for impressing such signals on the sawtooth waveforms produced by the wave generator and on the primaries of the pair of pulse transformers whereby as each transformer of said pair of transformers is enabled it will trigger the set of rectifiers to which it is coupled and permit the alternating current powering means to drive the motor, and means for selecting the duration of the waveform produced by the wave generator so that the peak-point voltage of each sawtooth waveform is reached when two or more of the voltage signals are impressed thereon by the control circuit.

Claim 7

Wave generating apparatus for controlling the speed of a motor responsive to alternating current powering means, comprising: a full wave rectifying bridge network connectable to such a motor and operable to convert the sinusoidal current waveform of the powering means to a unidirectional current waveform in which the half cycles thereof are all of one polarity. two sets of controlled rectifiers incorporated in said bridge circuit, the rectifiers in each set being disposed in diametrically opposite branches of the bridge circuit and each having a gating terminal, a sawtooth wave generator coupled to the rectifying bridge network to receive the unidirectional current converted thereby and including a unijunction transistor normally biased in a high impedance condition and capacitive means coupled to said unijunction transistor and operative periodically to discharge therethrough when its charge attains the peak-point voltage of the unijunction transistor, a pair of pulse transformers having their secondaries coupled individually to the two sets of controlled rectifiers, a trigger circuit coupled to said pair of pulse transformers and including gating means responsive to successive sawtooth pulses delivered by said unijunction transistor to said pair of transformers for alternately enabling the same for the duration of each of the sawtooth pulses, a control circuit coupled to said capacitive means and to said unijunction transistor and including means responsive to the alternating current powering means for producing relatively low voltage signals coinciding in time with the zero crossings of the alternating current and further including means for impressing such signals on the sawtooth waveforms produced by the wave generator and on the primaries of the pair of pulse transformers whereby as each transformer of said pair of transformers is enabled it will trigger the set of rectifiers to which it is coupled and permit the alternating current powering means to drive the motor, and means for selecting the duration of the waveform produced by the wave generator so that the peak-point voltage of each sawtooth waveform is reached when two or more of the voltage signals are impressed thereon by the control circuit.

Claim 8

The apparatus defined in claim 4 characterized in that the waveform duration selecting means includes a plurality of resistances of different resistive values each capable when coupled into the circuit of the wave generator to cause the latter to produce sawtooth wave-shaped pulses having a time span approximately equivalent to a multiple number of half cycles of the alternating current of the power means, and further includes switch means for selectively coupling any one of the plurality of resistances into the circuit of the wave generator.

Claim 9

Wave generating apparatus for controlling the speed of a motor responsive to alternating current powering means, comprising: a full wave rectifying bridge network connectable to such a motor and operable to convert the sinusoidal current waveform of the powering means to a unidirectional current waveform in which the half cycles thereof are all of one polarity, two sets of controlled rectifiers incorporated in said bridge circuit, the rectifiers in each set being disposed in diametrically opposite branches of the bridge circuit and each having a gating terminal, a pair of pulse energy converting means each having an input and output and each further having its output connected to the gating terminal of an individual one of two sets of controlled rectifiers, a wave generator for generating sawtooth-shaped pulses and coupled to said rectifying bridge network to receive the unidirectional current converted thereby, a switching circuit coupled to said wave generator and said pair of pulse energy converting means and including gating means responsive to successive ones of said sawtooth pulses generated by said wave generator for alternately enabling said pair of energy converting means for the duration of each of the sawtooth pulses, a control circuit including means responsive to the alternating current powering means for producing relatively low voltage signals coinciding in time with the zero crossings of the alternating current and further including means for impressing such voltage signals on the sawtooth waveforms produced by the wave generator and also for applying such voltage signals to the inputs of said pair of pulse energy converting means whereby as each one of the pair of energy converting means is enabled it will be pulsed by said voltage signals and trigger the firing of the set of rectifiers to which the enabled one is connected thereby permitting the alternating current power means to drive the motor, and means for selecting the duration of the waveform produced by the wave generator so that the peak-point voltage of each sawtooth waveform is reached at a time when one of the voltage signals is impressed thereon by the control circuit.

Claim 10

Wave generating apparatus for controlling the speed of a motor responsive to alternating current powering means, comprising: a full wave rectifying bridge network connectable to such a motor and operable to convert the sinusoidal current waveform of the powering means to a unidirectional current waveform in which the half cycles thereof are all of one polarity, two sets of controlled rectifiers incorporated in said bridge circuit, the rectifiers in each set being disposed in diametrically opposite branches of the bridge circuit and each having a gating terminal, a pair of pulse energy converting means each having an input and output and each further having its output connected to the gating terminal of an individual one of two sets of controlled rectifiers, a wave generator for generating sawtooth-shaped pulses and coupled to said rectifying bridge network to receive the unidirectional current converted thereby, a switching circuit coupled to said wave generator and said pair of pulse energy converting means and including gating means responsive to successive ones of said sawtooth pulses generated by said wave generator for alternately enabling said pair of energy converting means for the duration of each of the sawtooth pulses, a control circuit including means responsive to the alternating current powering means for producing relatively low voltage signals coinciding in time with the zero crossings of the alternating current and further including means for impressing such voltage signals on the sawtooth waveforms produced by the wave generator and also for applying such voltage signals to the inputs of said pair of pulse energy converting means whereby as each one of the pair of energy converting means is enabled it will be pulsed by said voltage signals and trigger the firing of the set of rectifiers to which the enabled one is connected thereby permitting the alternating current power means to drive the motor, and means for selecting the duration of the waveform produced by the wave generator so that the peak-point voltage of each sawtooth waveform is reached at a time when one of the voltage signals is impressed thereon by the control circuit.

Claim 11

Wave generating apparatus for controlling the speed of a motor responsive to alternating current powering means, comprising: bilateral network means connectable to such a motor and having two branches operable to convert the sinusoidal current waveform of the powering means to a unidirectional current waveform in which the half cycles thereof are all of one polarity, controlled rectifier means incorporated into the branches of said bilateral network means and being divided into two sets, the controlled rectifier means of each branch having an input terminal, wave generator means for generating sawtooth-shaped pulses of similar shape having a time span equal to the duration of two or more consecutive half cycles of the alternating current powering means, said generator means being coupled to said rectifying bridge network to receive the unidirectional current converted thereby, a switching circuit coupled to said wave generator Means and to the inputs of said controlled rectifier means and including means responsive to successive ones of said sawtooth pulses generated by said wave generator means for alternately enabling each of said controlled rectifier means for the time span of said sawtooth pulses, and a control circuit including means responsive to the alternating current powering means for producing voltage signals coinciding in time with the zero crossings of the alternating current and being effective at each such crossing to apply such voltage signals to the wave generator means thereby to drive the motor at a sub-multiple frequency of the alternating current powering means.

Claim 12

Wave generating apparatus for controlling the speed of a motor responsive to alternating current powering means, comprising: bilateral network means connectable to such a motor and having two branches operable to convert the sinusoidal current waveform of the powering means to a unidirectional current waveform in which the half cycles thereof are all of one polarity, controlled rectifier means incorporated into the branches of said bilateral network means and being divided into two sets, the controlled rectifier means of each branch having an input terminal, wave generator means for generating sawtooth-shaped pulses of similar shape having a time span equal to the duration of two or more consecutive half cycles of the alternating current powering means, said generator means being coupled to said rectifying bridge network to receive the unidirectional current converted thereby, a switching circuit coupled to said wave generator Means and to the inputs of said controlled rectifier means and including means responsive to successive ones of said sawtooth pulses generated by said wave generator means for alternately enabling each of said controlled rectifier means for the time span of said sawtooth pulses, and a control circuit including means responsive to the alternating current powering means for producing voltage signals coinciding in time with the zero crossings of the alternating current and being effective at each such crossing to apply such voltage signals to the wave generator means thereby to drive the motor at a sub-multiple frequency of the alternating current powering means.

Claim 13

The apparatus as defined in claim 7 wherein means is included in the control circuit for impressing said voltage signals on the sawtooth waveforms produced by the waveform generator so that the peak-point voltage of each sawtooth waveform is reached at a time when one of said voltage signals is impressed thereon.

Claim 14

Wave generating apparatus for controlling the speed of a motor responsive to alternating current powering means, comprising: bilateral network means connectable to such a motor and having two branches operable to convert the sinusoidal current waveform of the powering means to a unidirectional current waveform in which the half cycles thereof are all of one polarity, controlled rectifier means incorporated into the branches of said bilateral network means and being divided into two sets, the controlled rectifier means of each branch having an input terminal, a wave generator for generating sawtooth-shaped pulses of similar shape having a time span equal to the duration of two or more consecutive half cycles of the alternating current powering means, said generator being coupled to said rectifying bridge network to receive the unidirectional current converted thereby, a switching circuit coupled to said wave generator and to the inputs of said controlled rectifier means and including means responsive to successive ones of said sawtooth pulses generated by said wave generator for alternately enabling each of said controlled rectifier means for the time span of said sawtooth pulses, and a control circuit including means responsive to the alternating current powering means for producing voltage signals coinciding in time with the zero crossings of the alternating current and being effective at each such crossing to apply such voltage signals to the wave generator thereby to drive the motor at a sub-multiple frequency of the alternating current powering means, and means for varying the time span of the sawtooth-shaped pulses from two to a higher number of consecutive half cycles of the alternating current powering means.

Claim 15

Wave generating apparatus for controlling the speed of a motor responsive to alternating current powering means, comprising: bilateral network means connectable to such a motor and having two branches operable to convert the sinusoidal current waveform of the powering means to a unidirectional current waveform in which the half cycles thereof are all of one polarity, controlled rectifier means incorporated into the branches of said bilateral network means and being divided into two sets, the controlled rectifier means of each branch having an input terminal, a wave generator for generating sawtooth-shaped pulses of similar shape having a time span equal to the duration of two or more consecutive half cycles of the alternating current powering means, said generator being coupled to said rectifying bridge network to receive the unidirectional current converted thereby, a switching circuit coupled to said wave generator and to the inputs of said controlled rectifier means and including means responsive to successive ones of said sawtooth pulses generated by said wave generator for alternately enabling each of said controlled rectifier means for the time span of said sawtooth pulses, and a control circuit including means responsive to the alternating current powering means for producing voltage signals coinciding in time with the zero crossings of the alternating current and being effective at each such crossing to apply such voltage signals to the wave generator thereby to drive the motor at a sub-multiple frequency of the alternating current powering means, and means for varying the time span of the sawtooth-shaped pulses from two to a higher number of consecutive half cycles of the alternating current powering means.

Claim 16

The apparatus as defined in claim 9 wherein the means for varying the time span of the sawtooth pulses includes a plurality of impedances of different values each capable when coupled into the circuit of the wave generator to cause the latter to produce a sawtooth wave-shaped pulse of a time span differing from the pulse caused to be produced by any other of said impedances, and further includes switch means for selectively coupling any one of the plurality of impedances into the circuit of the wave generator.

Claim 17

A control circuit for generating alternating current pulses at a sub-multiple frequency of an alternating current reference voltage, comprising: bilateral network means connectable to an alternating current reference voltage and having two branch portions, controlled rectifier means incorporated into each of the branch portions of said bilateral network and each having an input terminal, means for generating pulses having a time span equal to the duration of a plural number of consecutive half cycles of the alternating current reference voltage, circuit means coupled to said generating means and to the inputs of said controlled rectifier means and including means responsive to successive ones of said pulseS for alternately enabling each of said controlled rectifier means for the time span of said pulses, and a control circuit including means responsive to the reference voltage for producing voltage signals coinciding in time with the zero crossings of the alternating current of the reference voltage and being effective at each such crossing to apply such voltage signals to the means for generating pulses thereby to supply alternating current at a sub-multiple frequency of the reference voltage.

Claim 18

A control circuit for generating alternating current pulses at a sub-multiple frequency of an alternating current reference voltage, comprising: bilateral network means connectable to an alternating current reference voltage and having two branch portions, controlled rectifier means incorporated into each of the branch portions of said bilateral network and each having an input terminal, means for generating pulses having a time span equal to the duration of a plural number of consecutive half cycles of the alternating current reference voltage, circuit means coupled to said generating means and to the inputs of said controlled rectifier means and including means responsive to successive ones of said pulseS for alternately enabling each of said controlled rectifier means for the time span of said pulses, and a control circuit including means responsive to the reference voltage for producing voltage signals coinciding in time with the zero crossings of the alternating current of the reference voltage and being effective at each such crossing to apply such voltage signals to the means for generating pulses thereby to supply alternating current at a sub-multiple frequency of the reference voltage.

Claim 19

The apparatus as defined in claim 11 wherein means is included for utilizing certain of said voltage signals for timing the start and termination of the pulses produced by said pulse generating means.

Claim 20

The apparatus as defined in claim 11 wherein the pulses produced by said pulse generating means are of the same sawtooth formation.

Claim 21

The apparatus as defined in claim 11 wherein the pulses produced by said pulse generating means are of the same sawtooth formation and wherein means is included in the control circuit for impressing a plural number of said voltage signals as voltage spikes on each of said sawtooth-shaped pulses and for utilizing certain of such spikes for controlling the start and termination of the sawtooth-shaped pulses.

Claim 22

A control circuit for generating alternating current pulses at a sub-multiple frequency of an alternating current reference voltage, comprising: bilateral network means connectable to an alternating current reference voltage and having two branch portions, controlled rectifier means incorporated into each of the branch portions of said bilateral network and each having an input terminal, means for generating pulses having a time span equal to the duration of a plural number of consecutive half cycles of the alternating current reference voltage, circuit means coupled to said generating means and to the inputs of said controlled rectifier means and including means responsive to successive ones of said pulses for alternately enabling each of said controlled rectifier means for the time span of said pulses, and a control circuit including means responsive to the reference voltage for producing voltage signals coinciding in time with the zero crossings of the alternating current of the reference voltage and being effective at each such crossing to apply such voltage signals to the means for generating pulses thereby to supply alternating current at a sub-multiple frequency of the reference voltage, and means for varying the time span of the pulses produced by said generating means from two consecutive half cycles of the alternating current of the reference voltage to a higher number of such consecutive half cycles.

Claim 23

A control circuit for generating alternating current pulses at a sub-multiple frequency of an alternating current reference voltage, comprising: bilateral network means connectable to an alternating current reference voltage and having two branch portions, controlled rectifier means incorporated into each of the branch portions of said bilateral network and each having an input terminal, means for generating pulses having a time span equal to the duration of a plural number of consecutive half cycles of the alternating current reference voltage, circuit means coupled to said generating means and to the inputs of said controlled rectifier means and including means responsive to successive ones of said pulses for alternately enabling each of said controlled rectifier means for the time span of said pulses, and a control circuit including means responsive to the reference voltage for producing voltage signals coinciding in time with the zero crossings of the alternating current of the reference voltage and being effective at each such crossing to apply such voltage signals to the means for generating pulses thereby to supply alternating current at a sub-multiple frequency of the reference voltage, and means for varying the time span of the pulses produced by said generating means from two consecutive half cycles of the alternating current of the reference voltage to a higher number of such consecutive half cycles.

Claim 24

In a control circuit for generating alternating current pulses at a sub-multiple frequency of an alternating current reference voltage: a full wave rectifying bridge network connectable to the alternating current reference voltage and operable to convert the sinusoidal current waveform of the source to an unidirectional current waveform in which the half cycles thereof are all of one polarity, controlled rectifier means coupled to the rectifying bridge network and having terminal means for gating the same, a sawtooth waveform generator circuit means coupled to the rectifying bridge network to receive the unidirectional current converted thereby and connected to the terminal means of said controlled rectifier means and being operable to generate and deliver successive sawtoothed shaped pulses of like polarity thereto, said waveform generator circuit means including one or more impedances each having an impedance value different from any other such impedance and being capable when coupled into the circuit of the waveform generator circuit means to produce a sawtooth-shaped pulse having a time span equal to the duration of two or more consecutive half cycles of the reference voltage but differing from one another in the number of half cycles in the span thereof and furtHer including means for selectively coupling each such impedance into the waveform generator circuit, and control means connectable to the alternating current reference voltage and responsive thereto for producing voltage signals coupled to said waveform generator circuit means for timing the start and termination of the sawtooth waveforms generated by said waveform generator circuit means, said voltage signals extending in the same direction of amplitude as the sawtooth waveforms and coinciding in time to all of the zero crossings of the reference voltage, whereby the coupling of any one of said impedances into the waveform generator circuit means will cause the control circuit to supply voltage at a sub-multiple frequency of that of the reference voltage.

Claim 25

In a control circuit for generating alternating current pulses at a sub-multiple frequency of an alternating current reference voltage: a full wave rectifying bridge network connectable to the alternating current reference voltage and operable to convert the sinusoidal current waveform of the source to an unidirectional current waveform in which the half cycles thereof are all of one polarity, controlled rectifier means coupled to the rectifying bridge network and having terminal means for gating the same, a sawtooth waveform generator circuit means coupled to the rectifying bridge network to receive the unidirectional current converted thereby and connected to the terminal means of said controlled rectifier means and being operable to generate and deliver successive sawtoothed shaped pulses of like polarity thereto, said waveform generator circuit means including one or more impedances each having an impedance value different from any other such impedance and being capable when coupled into the circuit of the waveform generator circuit means to produce a sawtooth-shaped pulse having a time span equal to the duration of two or more consecutive half cycles of the reference voltage but differing from one another in the number of half cycles in the span thereof and furtHer including means for selectively coupling each such impedance into the waveform generator circuit, and control means connectable to the alternating current reference voltage and responsive thereto for producing voltage signals coupled to said waveform generator circuit means for timing the start and termination of the sawtooth waveforms generated by said waveform generator circuit means, said voltage signals extending in the same direction of amplitude as the sawtooth waveforms and coinciding in time to all of the zero crossings of the reference voltage, whereby the coupling of any one of said impedances into the waveform generator circuit means will cause the control circuit to supply voltage at a sub-multiple frequency of that of the reference voltage.