Slow start-stop motor control system

Claim 2

In a motor control system including an alternating current (AC) voltage and current source, an AC motor means and an AC power control means, said power control means comprising: a power switching network having an input end and an output end, said output end being coupled to said motor means, said power switching network transferring electrical power from the input end to the output end; a voltage switch means for connecting AC voltage from the source to the input of said switching network; an operational control means connected to said switching network, said operational control means after said voltage is connected to the input end of the switching network causing current conduction from said input end to the motor means to increase progressively from an initial time period during the first conducting cycle to a greater time period per cycle of said AC source current and thereby provide respectively an initial motor torque and a greater motor torque; reference means for generating a reference signal during each cycle of said AC voltage when said current conduction is being progressively increased; means for generating a voltage decaying function signal, the cooperation of said function signal with said reference signal causing said period of current conduction per cycle of AC source current to increase from the initial to the greater period per cycle; means for delaying the generation of said function signal during a delay or first time interval after said voltage switch means connects said voltage from the source to the network, said current increasing from said initial to said greater period of current conduction during a second time interval; and means for resetting said function signal to an initial voltage level during said delay interval.

Claim 3

In a motor control system including an alternating current (AC) voltage and current source, an AC motor means and an AC power control means, said power control means comprising: a power switching network having an input end and an output end, said output end being coupled to said motor means, said power switching network transferring electrical power from the input end to the output end; a voltage switch means for connecting AC voltage from the source to the input of said switching network; an operational control means connected to said switching network, said operational control means after said voltage is connected to the input end of the switching network causing current conduction from said input end to the motor means to increase progressively from an initial time period during the first conducting cycle to a greater time period per cycle of said AC source current and thereby provide respectively an initial motor torque and a greater motor torque; reference means for generating a reference signal during each cycle of said AC voltage when said current conduction is being progressively increased; means for generating a voltage decaying function signal, the cooperation of said function signal with said reference signal causing said period of current conduction per cycle of AC source current to increase from the initial to the greater period per cycle; means for delaying the generation of said function signal during a delay or first time interval after said voltage switch means connects said voltage from the source to the network, said current increasing from said initial to said greater period of current conduction during a second time interval; and means for resetting said function signal to an initial voltage level during said delay interval.

Claim 4

In a motor control system including an alternating current (AC) voltage and current source, an AC motor means and an AC power control means, said power control means comprising: a power switching network having an input end and an output end, said output end being coupled to said motor means, said power switching network transferring electrical power from the input end to the output end; a voltage switch means for connecting AC voltage from the source to the input of said switching network; an operational control means connected to said switching network, said operational control means after said voltage is connected to the input end of the switching network causing current conduction from said input end to the motor means to increase progressively from an initial time period during the first conducting cycle to a greater time period per cycle of said AC source current and thereby provide respectively an initial motor torque and a greater motor torque; reference means for generating a reference signal during each cycle of said AC voltage when said current conduction is being progressively increased; means for generating a voltage decaying function signal, the cooperation of said function signal with said reference signal causing said period of current conduction per cycle of AC source current to increase from the initial to the greater period per cycle; means for delaying the generation of said function signal during a delay or first time interval after said voltage switch means connects said voltage from the source to the network, said current increasing from said initial to said greater period of current conduction during a second time interval; and means for resetting said function signal to an initial voltage level during said delay interval.

Claim 5

The control means of claim 1, wherein said operational control means includes means for decaying said function signal at a first rate during said second time interval and means for decaying said function signal at a second rate during a third time interval, said rate of decay during said third time interval being substantially greater than during said second time interval and thereby enabling the current conduction period per AC current cycle to more rapidly increase until said greater torque is reached.

Claim 6

In an alternating current (AC) energy switching system including an AC current and voltage source, a load means to receive energy from said source and an AC power control means, said power control means comprising: a power switching network having an input end and an output end, said output end being operatively coupled to said load, said power switching network transferring power from the input end to the output end; a voltage switch means having an input coupled to said AC source and an output for connecting said AC voltage from the source to the input of said switching network; an operational control means connected to said switching network, said operational control means after said voltage is connected to the input end of the switching network, causing current conduction through the switching network to increase from an initial time period to a greater time period per cycle of said AC source current; and a direct current (DC) power supply having an AC input and a DC output, said AC input of the supply being coupled to the output of said voltage switch means and the DC output of the supply being connected to the operational control means.

Claim 7

In an alternating current (AC) energy switching system including an AC current and voltage source, a load means to receive energy from said source and an AC power control means, said power control means comprising: a power switching network having an input end and an output end, said output end being operatively coupled to said load, said power switching network transferring power from the input end to the output end; a voltage switch means having an input coupled to said AC source and an output for connecting said AC voltage from the source to the input of said switching network; an operational control means connected to said switching network, said operational control means after said voltage is connected to the input end of the switching network, causing current conduction through the switching network to increase from an initial time period to a greater time period per cycle of said AC source current; and a direct current (DC) power supply having an AC input and a DC output, said AC input of the supply being coupled to the output of said voltage switch means and the DC output of the supply being connected to the operational control means.

Claim 8

An energy switching system for switching alternating current (AC) and voltage from an AC source to a load, comprising: a power switching network including a plurality of solid state switches, each of the switches having an input and an output; an electro-mechanical switch means including a line switch controlled by a manual switch having an on-position and an off-position, said line switch connecting and disconnecting the AC source from the input of said solid state switches when said manual switch is respectively in the on and off-positions; a make-arc suppressor means for causing a first disabling signal to be generated for preventing current conduction through said switching network for a time delay interval after the electro-mechanical switch means connects said AC voltage to the input of the solid state switches; and a break-arc suppressor means for causing a second disabling signal to be generated for preventing current conduction through said solid state switch means prior to said line switch disconnecting said voltage after said manual switch is switched from the on to the off-position.

Claim 9

An energy switching system for switching alternating current (AC) and voltage from an AC source to a load, comprising: a power switching network including a plurality of solid state switches, each of the switches having an input and an output; an electro-mechanical switch means including a line switch controlled by a manual switch having an on-position and an off-position, said line switch connecting and disconnecting the AC source from the input of said solid state switches when said manual switch is respectively in the on and off-positions; a make-arc suppressor means for causing a first disabling signal to be generated for preventing current conduction through said switching network for a time delay interval after the electro-mechanical switch means connects said AC voltage to the input of the solid state switches; and a break-arc suppressor means for causing a second disabling signal to be generated for preventing current conduction through said solid state switch means prior to said line switch disconnecting said voltage after said manual switch is switched from the on to the off-position.

Claim 10

In a motor control system including a three-phase alternating current (AC) voltage and current source, said three-phase voltage including phase A voltage, phase B voltage and phase C voltage, an AC three-phase motor means and an AC three-phase power control means, said three-phase power control means comprising: a power switching network including at least a first, a second and a third switch, each of said switches having an input and an output, said output being operatively connected to the motor means, said switches each having an on-condition and an off-condition; a voltage switch means for connecting phase A voltage to the input of said first switch, phase B voltage to the input of said second switch, and phase C voltage to the input of said third switch; and an operational control means connected to said switching network, said operational control means after said phase A, phase B and phase C voltages are connected to the inputs of the switches causing the corresponding phase A, phase B and phase C current conduction to the motor means per cycle to increase from an initial time period to a greater time period, and thereby provide respectively an initial motor torque and a greater motor torque.

Claim 11

In a motor control system including a three-phase alternating current (AC) voltage and current source, said three-phase voltage including phase A voltage, phase B voltage and phase C voltage, an AC three-phase motor means and an AC three-phase power control means, said three-phase power control means comprising: a power switching network including at least a first, a second and a third switch, each of said switches having an input and an output, said output being operatively connected to the motor means, said switches each having an on-condition and an off-condition; a voltage switch means for connecting phase A voltage to the input of said first switch, phase B voltage to the input of said second switch, and phase C voltage to the input of said third switch; and an operational control means connected to said switching network, said operational control means after said phase A, phase B and phase C voltages are connected to the inputs of the switches causing the corresponding phase A, phase B and phase C current conduction to the motor means per cycle to increase from an initial time period to a greater time period, and thereby provide respectively an initial motor torque and a greater motor torque.

Claim 12

The three-phase power control means of claim 5, wherein said operational control means comprises: reference means for generating a first reference signal, a second reference signal and a third reference signal; and function generating means for generating a function signal, the cooperation of said function signal with said first, second and third reference signals causing said period of current conduction per cycle of the AC phase A, phase B and phase C current to increase from the initial to the greater period.

Claim 13

The three-phase power control means of claim 6, wherein; said voltage switch means is an electro-mechanical switch means having an on-condition and an off-condition for respectively connecting and disconnecting said phase A, B and C voltages respectively to said first, second and third switch means; and said first, second and third switches being solid state static switches, said operational control means including a ''''make'''' arc suppressor mean to cause a disabling signal to be generated for preventing current conduction through said static switch members for a predetermined time period after said electro-mechanical switch means has connected said phase A, B and C voltages to the inputs of said static switches.

Claim 14

The three-phase power control means of claim 7, wherein: said electro-mechanical switch means includes a plurality of line switches controlled by a manual switch having an on-position and an off-position, said line switches connecting and disconnecting phase A, phase B and phase C voltages to the corresponding inputs of the static switches when said manual switch is respectively in the on-position and the off-position; and said operational control means includes a break-arc suppressor means for causing a disabling signal to be generated prior to said line switches disconnecting said phase A, B and C voltages after said manual switch is switched from the on to the off-position, to prevent conduction of phase A, B and C current at the instant said line switch disconnects said phase voltages.

Claim 15

The power control means of claim 8, wherein said function generator means comprises: a delay circuit to prevent phase A, B and C current conduction for a delay time interval after phase A, B and C voltages are connected to the corresponding static switches; and a timing circuit including reset means for setting said function signal at an initial voltage level during said delay time interval and a first varying means for varying the voltage of said function signal from said initial level during the second predetermined time period, whereby the current conduction period through the first, second and third static switches increases with time per corresponding input phase A, phase B and phase C current cycle.

Claim 16

The power control means of claim 9 wherein said timing circuit includes second varying means for varying the voltage of said function signal during a third time interval, the rate of variation during said third interval being substantially greater than said second rate and thereby enabling the current conduction period for the first, second and third static switches to accelerate its rate of increase per corresponding input phase A, phase B and phase C current cycle until said greater torque is reached.

Claim 17

The power control means of claim 9 wherein each of the AC phase voltages is 120* out of phase from each other and said operational control means includes: a phasing network having a first, second and third input for connecting respectively said phase A, B and C voltages, said phasing network generating square wave outputs corresponding respectively to the positive portions of the phase A, B and C voltages and square wave outputs corresponding to the negative portions of the phase A, B and C voltages; a ramp network connected to the outputs of the phasing network to provide a ramp A signal generated during the phase A voltage cycle, a ramp B signal generated during the phase B voltage cycle, and a ramp C signal generated during the phase C voltage cycle; and a comparator network including a comparator A having a first input coupled to the output for said ramp A signal, a comparator B coupled to said ramp B signal and a comparator C coupled to said ramp C signal, each of said comparators including a second input connected to said function generator signal, each of said comparators A, B and C providing respectively an output drive signal A, B and C when the corresponding ramp signal A, B and C is greater than the function signal, whereby said output drive signals A, B and C causing respectively said first, second and third switches to switch from an off-condition to an on-condition to permit electrical power to be transferred from the input of the corresponding switch of the switching network to the motor means.

Claim 18

The power control means of claim 11 wherein: the cooperation of said phasing network and ramp network causing each of said ramp signals A, B and C to begin at substantially the 60* point of the corresponding phase voltages A, B and C.

Claim 19

The power control means of claim 11 wherein the current in each of said phases lags the voltage by substantially 60*, and the cooperation of said phasing network and ramp network causing each of said ramp signals A, B and C to begin at substantially the 60* point and end at the 180* point of the corresponding phase voltages A, B and C, said thyristors being triggered into the on-condition between 60* and 180* of the corresponding phase voltage, so that the conduction period of each phase to said motor means is at least 60*.

Claim 20

The power control means of claim 11 wherein: said first, second and third switches include respectively a first, second and third thyristor, each of said thyristors having an emitter, gate and collector whereby the output signals of comparators A, B and C cause a firing voltage to be applied to the gates respectively of said first, second and third thyristors, so that said thyristors fire into said on-conditioning, said thyristors switching from the on to the off-condition when the corresponding phase A, B and C phase currents reverse their polarities.

Claim 21

The power control means of claim 5, wherein said first, second and third switches each includes an on-condition and an off-condition, said operational control means includes: a phase A means having an input connected to said phase A voltage, said phase A means having a first output for providing square wave signals corresponding to the positive polarity portions of the phase A voltage (A) and a second output for providing square wave signals corresponding to the negative polarity portions of the phase A voltage (A); a phase B means having an input connected to said phase B voltage, said phase B means having a first output for providing square wave signals corresponding to the positive polarity portions of the phase B voltage (B) and a second output for providing square wave outputs corresponding to the negative polarity portions of the phase B voltage (B); a phase C means having an input connected to said phase C voltage, said phase C means having a first output for providing square wave signals corresponding to the positive polarity portions Of the phase C voltages (C) and a second output for providing square wave signals corresponding to the negative polarity portions of the phase C voltage (C); a ramp A gate means having a first input, a second input and an output, said first input being coupled to one of the outputs of the phase A means and said second input being coupled to one of the outputs of the phase C means, whereby one of said input signals to ramp A gate is representative of positive polarity portions and the other input is representative of negative polarity portions, said ramp gate means including means for converting said inputs to the A gate means to a ramp A signal at said ramp A output having a substantially 120* period per phase A voltage cycle; a ramp B gate means having a first input, a second input and an output, said first input being coupled to one of the outputs of the phase B means and a second input coupled to the other of the outputs of the phase A means, whereby one of said input signals to ramp B gate is representative of positive polarity portions, said ramp B gate means including means for converting said inputs to the B gate means to a ramp B signal at the ramp B output having a substantially 120* period per phase B voltage cycle; a ramp C gate means having a first input, a second input and an output, said first input being coupled to the other of the outputs of the phase C means and a second input being coupled to the other of the outputs of the phase B means whereby one of said input signals to ramp C gate is representative of positive polarity portions and the other input is representative of negative polarity portions, said ramp C gate means including means for converting said inputs to the ramp C gate means to a ramp C signal at the ramp C output having a substantially 120* period per phase C voltage cycle, said ramp A, B and C signals being reference signals for determining the point along the corresponding phase A, B and C voltage cycle said first, second and third switches respectively switch from the off to the on-condition.

Claim 22

The power control means of claim 15, wherein said operational control means includes: function generator comprising means for generating a function signal decaying with time, said function signal appearing at an output of the generator; a comparator A means having a first input coupled to the output of said ramp A gate means; a comparator B means having a first input coupled to the output of the ramp B gate means; a comparator C means having a first input coupled to the output of the ramp C gate means, the second inputs of each of said comparators being coupled to said output of the function generator means, said comparator A, B and C providing respectively an output signal A, B and C when the corresponding input ramp A, B and C signals exceed said function signal; AND gate A having one input connected to the output of the comparator A; AND gate B having one input connected to the output of comparator B; AND gate C having one input connected to the output of comparator C; an oscillator means for generating pulses at a substantially greater frequency than the frequency of the phase A, B and C voltage, said oscillator means having an output connected to a second input to said AND gates A, B and C, said AND gates A, B and C coupling said input oscillator pulses to the corresponding AND gate outputs when the corresponding said A, B and C signals from the comparators appear at said one input of the AND gates; and coupling means for connecting the pulses at the output of AND gates A, B and C respectively to the first, second and third switches causing these switches to switch from an off to an on-condition.

Claim 23

The motor control system of claim 16 wherein lines A, B and C are connected respectively to said first, secoNd and third switch, said phase A, B and C voltages being respectively the voltages between lines A and B, B and C, and C and A, said first and second inputs to ramp A gate being respectively A and C square waves, said first and second inputs to ramp B gate being respectively B and A, said first and second inputs to ramp C gate being respectively C and B.

Claim 24

The motor control system of claim 17 wherein the current corresponding to each of said phase voltages lags the voltage by substantially 60*, said ramp signals A, B and C beginning at substantially the 60* point and ending at substantially the 180* point of the corresponding phase voltages A, B and C, said first, second and third switches each including at least one thyristor, said ramp signal causing said thyristors to trigger into the on-condition between 60* and 120* of the corresponding phase voltage, so that the conduction period of each phase to said motor means is at least 60*.

Claim 25

The motor control system of claim 18 includes a break-arc suppressor means comprising means for generating a break-arc signal at its output prior to said voltage connecting means severing said AC voltages from said lines A, B and C, and said function generator means comprises: a delay circuit including means for generating a delay signal for a delay time interval after said voltage connecting means connects AC voltage to lines A, B and C, said delay signal appearing at an output of said delay circuit; a timing circuit including reset means for setting said function signal at an initial voltage level during said delay time interval, said function signal varying from said initial level during the second predetermined time period, whereby the current conduction period through the first, second and third static switches increases with time per corresponding input phase A, phase B and phase C current cycle; and an OR gate including a first input, a second input and an output, said first input being connected to the output of the delay circuit, said second input being connected to the output of the break-arc suppressor means, said output of the OR gate being connected to an input of said oscillator means, said OR gate generating an inhibit signal at its output in response to either said delay signal or said break-arc signal, said inhibit signal preventing operation of said oscillator and thereby preventing said thyristors from firing from the off-condition to the on-condition.

Claim 26

The power control means of claim 19 includes a comparator means having a first input connected to a reference voltage, a second input connected to said function generator, and an output also connected to said function generator, the signal at said second input varying in magnitude in response to the voltage variation of said function signal, said comparator means providing an output when the signal at said second input reaches a predetermined level in comparison with said reference voltage to cause an increase in the rate of decay of said function signal.

Claim 27

The power control means of claim 5, wherein said first, second and third switches of the switching network each includes a thyristor having a cathode, gate and anode, whereby the phase A current flows through the thyristor of the first switch from the source to the motor means and return to the source via a diode of at least one of the other switches.

Claim 28

The motor control system of claim 5, wherein said motor means includes: a first stator winding to provide a first ''''full'''' speed and a second stator winding to provide a second ''''full'''' speed greater than said first full speed; static switch means for switching either said first and second stator windings into the stator circuit of the motor means; and means cooperating with the stator switch means to activate said operational control means whereby the phase A, B and C current conduction to the motor means per cycle increases from said initial time period to said greater time period after the stator switch means switches from said first to the second winding, said greater period of conduction enabling said motor to operate at said second full speed.

Claim 29

The motor control system of claim 5 wherein said greater torque is full torque of the motor means and includes a contactor means for switching said first, second and third switches out of the circuit and connecting said phase A, B and C voltages to said motor means, when said motor means reaches full torque.

Claim 30

In a motor control system including an alternating current (AC) voltage and current source, an AC motor means and an AC power control means, said power control means comprising: a power switching network having an input end and an output end, said output end being coupled to said motor means, said power switching network transferring electrical power from the input end to the output end; an electro-mechanical switch means including a line switch controlled by a manual switch, said manual switch having an on-position and an off-position, said line switch connecting and disconnecting said AC voltage when said manual switch is respectively in the on and off-position; an operational control means connected to said switching network, said operational control means after said voltage is connected to the input end of the switching network causing current conduction from said input end to the motor means to increase from an initial time period to a maximum time period per cycle of said AC current and thereby provide respectively an initial motor torque and a full motor torque; and a break-arc suppressor means to cause a disabling signal to be generated after said manual switch is switched from the on-position to the off-position, for preventing said switching network from transferring said electrical power prior to said line switch disconnecting said AC voltage.

Claim 31

In a motor control system including an alternating current (AC) voltage and current source, an AC motor means and an AC power control means, said power control means comprising: a power switching network having an input end and an output end, said output end being coupled to said motor means, said power switching network transferring electrical power from the input end to the output end; an electro-mechanical switch means including a line switch controlled by a manual switch, said manual switch having an on-position and an off-position, said line switch connecting and disconnecting said AC voltage when said manual switch is respectively in the on and off-position; an operational control means connected to said switching network, said operational control means after said voltage is connected to the input end of the switching network causing current conduction from said input end to the motor means to increase from an initial time period to a maximum time period per cycle of said AC current and thereby provide respectively an initial motor torque and a full motor torque; and a break-arc suppressor means to cause a disabling signal to be generated after said manual switch is switched from the on-position to the off-position, for preventing said switching network from transferring said electrical power prior to said line switch disconnecting said AC voltage.

Claim 32

In a motor control system including an alternating current (AC) voltage and current source, an AC motor means and an AC power control means, said power control means comprising: a power switching network having an input end and an output end, said output end being coupled to said motor means, said network including a plurality of static switches, each of the static switches having an off-condition and an on-condition, said static switching transfering electrical power from the input end to the output end when in said on-condition; a voltage switch means for connecting AC voltage from the source to the input of the switching network in a first direction and in a second direction; a phasing network having a plurality of input voltages corresponding to the voltages in a loop of a source AC voltages, said phasing network being connected to the input end of the switching network, the output of said phasing network being a plurality of square wave voltages, one set of square wave outputs corresponding to the positive portions of said input AC voltages and a second set of square wave outputs corresponding to the negative portions of the said input AC voltages; and a ramp gate network connected to the output of the phasing network to provide a plurality of ramp signals of like number as the input voltages to the phasing network, whereby only one of the ramp signals is being generated at any one instant, when said voltage switch means is connected in either of said directions, each ramp signal corresponding to a different one of said static switches and cooperating with other signal means to switch said static switches into conduction.

Claim 33

In a motor control system including an alternating current (AC) voltage and current source, an AC motor means and an AC power control means, said power control means comprising: a power switching network having an input end and an output end, said output end being coupled to said motor means, said network including a plurality of static switches, each of the static switches having an off-condition and an on-condition, said static switching transfering electrical power from the input end to the output end when in said on-condition; a voltage switch means for connecting AC voltage from the source to the input of the switching network in a first direction and in a second direction; a phasing network having a plurality of input voltages corresponding to the voltages in a loop of a source AC voltages, said phasing network being connected to the input end of the switching network, the output of said phasing network being a plurality of square wave voltages, one set of square wave outputs corresponding to the positive portions of said input AC voltages and a second set of square wave outputs corresponding to the negative portions of the said input AC voltages; and a ramp gate network connected to the output of the phasing network to provide a plurality of ramp signals of like number as the input voltages to the phasing network, whereby only one of the ramp signals is being generated at any one instant, when said voltage switch means is connected in either of said directions, each ramp signal corresponding to a different one of said static switches and cooperating with other signal means to switch said static switches into conduction.

Claim 34

In an alternating current (AC) energy switching system including an AC current and voltage source, a load means to receive energy from said source, a power control means for controlling the energy transferred from the source to the load and a voltage switching means for connecting the voltage from the source to the poWer control means in one polarity or in a reverse polarity, said power control means comprising: a power switching network having an input end for coupling said voltage switching means thereto and an output end for coupling said load thereto, said switching network including at least two switch means for providing current flow from the input end to the output end in one direction or in a reverse direction, each of said switch means including an on-condition and an off-condition; means for cooperating with said voltage switching means to enable said voltage switching means to switch the voltage to the switching network from said one polarity to said reverse polarity and thereby cause said current flowing in said one direction to flow in the reverse direction; and an operational means connected to the switching network, said operational means including turn-on means for switching one of said switch means to the on-condition from the off-condition during each cycle of said AC current when the other of said switch means is in the off-condition, said turn-on means including means for increasing the period of current conduction through said one and said other switch means for each said cycle of AC current from an initial period to a maximum period.

Claim 35

In an alternating current (AC) energy switching system including an AC current and voltage source, a load means to receive energy from said source, a power control means for controlling the energy transferred from the source to the load and a voltage switching means for connecting the voltage from the source to the poWer control means in one polarity or in a reverse polarity, said power control means comprising: a power switching network having an input end for coupling said voltage switching means thereto and an output end for coupling said load thereto, said switching network including at least two switch means for providing current flow from the input end to the output end in one direction or in a reverse direction, each of said switch means including an on-condition and an off-condition; means for cooperating with said voltage switching means to enable said voltage switching means to switch the voltage to the switching network from said one polarity to said reverse polarity and thereby cause said current flowing in said one direction to flow in the reverse direction; and an operational means connected to the switching network, said operational means including turn-on means for switching one of said switch means to the on-condition from the off-condition during each cycle of said AC current when the other of said switch means is in the off-condition, said turn-on means including means for increasing the period of current conduction through said one and said other switch means for each said cycle of AC current from an initial period to a maximum period.

Claim 42

In a power control system for controlling the transfer of alternating current (AC) voltage and current from an AC source to a load, said control system comprising: a power switcHing network having an input end and an output end for coupling the load thereto, said switching network including at least a first switch means and a second switch means for providing current conduction from the input end to the output end, each of said switch means having an on-condition and an off-condition; an operational means to progressively increase said current conduction per cycle of AC current from an initial time period to a greater time period and thereby provide respectively an initial current conduction and a greater current conduction per AC current cycle; and voltage switch means having an on-position and an off-position for respectively connecting and disconnecting said AC voltage from the input of the power switching network, said voltage switch means including means for generating a turn-on signal when switched from the off to the on-position to cause the starting of said current conduction.

Claim 43

In a power control system for controlling the transfer of alternating current (AC) voltage and current from an AC source to a load, said control system comprising: a power switcHing network having an input end and an output end for coupling the load thereto, said switching network including at least a first switch means and a second switch means for providing current conduction from the input end to the output end, each of said switch means having an on-condition and an off-condition; an operational means to progressively increase said current conduction per cycle of AC current from an initial time period to a greater time period and thereby provide respectively an initial current conduction and a greater current conduction per AC current cycle; and voltage switch means having an on-position and an off-position for respectively connecting and disconnecting said AC voltage from the input of the power switching network, said voltage switch means including means for generating a turn-on signal when switched from the off to the on-position to cause the starting of said current conduction.

Claim 44

The control system of claim 30, wherein each of said switch means includes a unidirectional device, said unidirectional device of one of said switch means providing a return path to said AC source for said current when the other of said switch means is in the on-condition, said voltage switch means including means for generating a turn-off signal when switched from on to the off-position to stop current flow through said power switching network.

Claim 45

The control system of claim 31 wherein each of said switch means includes a thyristor means in parallel with a diode means, each said thyristor means having said on-condition and said off-condition, the thyristor of one of said switch means when in the on-condition enabling said current to flow from said source to said load and the diode of the other of said switch means providing a return path for said current from the load to the source.

Claim 46

The control means of claim 30 wherein said voltage switch means includes: a forward switch means and a reverse switch means for connecting said AC voltage respectively in the forward and reverse directions, said forward and reverse switches each including an on-position and an off-position, said turn-on signal being generated when either said forward and reverse switches are switched from the off to the on-position.

Claim 47

In a power control system for controlling the transfer of alternating current (AC) voltage and current from an AC source to a load, said control system comprising: a power switching network having an input end for coupling said AC source thereto and an output end for coupling said load thereto, said switching network including at least two switch means for providing current flow from the input end to the output end, each of said switch means having an on-condition and an off-condition; turn-on means for switching one of said switch means to the on-condition from the off-condition during each cycle of said AC current when the other of said switch means is in the off-condition; reference means for generating a reference signal during each cycle of said AC voltage; and function generator means for generating a voltage decaying function signal, the cooperation of said function signal with said reference signal causing said period of current conduction to increase per cycle from an initial period of current conduction to a greater period of current conduction.

Claim 48

In a power control system for controlling the transfer of alternating current (AC) voltage and current from an AC source to a load, said control system comprising: a power switching network having an input end for coupling said AC source thereto and an output end for coupling said load thereto, said switching network including at least two switch means for providing current flow from the input end to the output end, each of said switch means having an on-condition and an off-condition; turn-on means for switching one of said switch means to the on-condition from the off-condition during each cycle of said AC current when the other of said switch means is in the off-condition; reference means for generating a reference signal during each cycle of said AC voltage; and function generator means for generating a voltage decaying function signal, the cooperation of said function signal with said reference signal causing said period of current conduction to increase per cycle from an initial period of current conduction to a greater period of current conduction.