Commutating circuit for electrical vehicle

Claim 2

An electrical power control system for an electrically powered vehicle having a motor for driving the vehicle along the earth''s surface, manual control means for varying the speed of the vehicle, electrical energy storage means having terminals for producing a direct current output voltage and for receiving electrical energy to recharge said storage menas and means for receiving energy from an external voltage source comprising: chopper circuit means for receiving at one terminal an input direct current voltage and producing at a second terminal a direct current voltage output including means for controlling the magnitude of said direct current output voltage, and switch means for connecting said chopper circuit in a first configuration between said terminals of electrical energy storage means and said motor for supplying electrical energy to said motor to drive said vehicle along the earth''s surface, in a second configuration between said terminals of energy storage means and said motor for recharging said storage means during regenerative braking and in a third configuration between said terminals of energy storage means and said energy receiving means for recharging said storage means from an external voltage source.

Claim 3

A system as in claim 1 wherein said first configuration includes a first mode for causing said vehicle to move forward, a second mode to cause said vehicle to move backward, a third mode to cause said vehicle to move forward and in which said storage means is connected directly to said motor and a fourth mode to cause said vehicle to move backward and in which said storage means is connected directly to said motor and wherein said second configuration includes a first mode in which said vehicle is moving forward and a second mode in which said vehicle is moving backwards.

Claim 4

A system as in claim 2 wherein said storage means is a battery having first and second terminals and said motor includes a field winding and an armature winding and wherein said switch means includes a first switch connecting one terminal of said battery to said one terminal of said chopper circuit means, a second switch connecting said one terminal of said chopper circuit to said second terminal of said chopper circuit, a third switch having a first position connecting one end of said series winding to one side of said armature winding and a second position, a fourth switch having a first position connecting the other end of said series winding to said one end of said armature winding and a second position and a fifth switch having a first position connecting said one terminal of said chopper circuit to said other end of said series winding when said fourth switch is in said second position and to said one end of said series winding when said third switch is in said second position, and a second position connecting the other terminal of said battery to said other end of said series winding when said fourth switch is in said second position and to said one end of said series winding when said third switch is in said second position.

Claim 5

A system as in claim 1 wherein said chopper circuit includes: first electronic switching means having first and second switch terminals and a gate terminal so that a current path is completed between said first and second terminals when a given voltage signal is applied to said gate terminal and is interrupted when a given back bias voltage is applied between said first and second terminals, second electronic switching means having first and second switch terminals and a gate terminal so that a current path is completed between said first and second terminals when a given voltage signal is applied to said gate terminal and is interrupted when a given back bias voltage is applied between said first and second terminals, third electronic switching means having first and second switch terminals and a gate terminal so that a current path is completed between said first and second terminals when a given voltage signal is applied to said gate terminal, means for connecting said first terminal of said first switching means to said first terminal of said third switching means, fourth electronic switching means having first and second switch terminals and a gate terminal so that a current path is completed between said first and second terminals when a given voltage signal is applied to said gate terminal, means for connecting said second terminal of said fourth switching means to said second terminal of said first switching means, fifth electronic switching means having first and second switch terminals and a gate terminal so that a current path is completed between said first and second terminals when a given voltage signal is applied to said gate terminals, means for connecting said first terminal of said second switching means to said first terminal of said fifth switching means, sixth electronic switching means having first and second switch terminals and a gate terminal so that a current path is completed between said first and second terminals when a given voltage signal is applied to said gate terminal, means for connecting said second terminal of said second switching means to said second terminal of said sixth switching means.

Claim 6

A system as in claim 4 wherein each of said switching means is a silicon controlled rectifier.

Claim 7

A system as in claim 4 further including: means for connecting together said first terminals of said first, second, fifth and sixth switching means to define a first circuit terminal, a first inductor having first and second terminals, means for connecting said first terminal of said first inductor to said second terminals of said first and fourth switching means, a second inductor having first and second terminals, means for connecting said first terminal of said second inductor to said second terminals of said second and sixth switching means, means for connecting together said second terminals of said first and second inductors to define a second circuit terminal, a capacitor having a first and second terminals, means for connecting said first terminal of said capacitor to said first terminal of said fourth switching means and said second terminal of said third switching means, and means for connecting said second terminal of said capacitor to said first terminal of said sixth switching means and said second terminal of said fifth switching means a first diode having first and second terminals, means for connecting said first terminal of said first diode to said first terminal of said first inductor, a second diode having first and second terminals, means for connecting said first terminal of said second diode to said first terminal of said second inductor, and means for connecting said second terminals of said first and second diodes to define a third circuit terminal.

Claim 8

A circuit as in claim 6 wherein said means for connecting said first terminal of said second inductor to said second terminals of said second and sixth switching means includes a third inductor and wherein said means for connecting said first terminal of said first inductor to said second terminals of said first and fourth switching means includes a fourth inductor.

Claim 9

A circuit as in claim 7 wherein the values of said first and second inductors are approximately 1,000 microhenrys and the values of said third and fourth inductors are approximately 50 microhenrys.

Claim 10

A circuit as in claim 6 further including a snubbing circuit connected between the first and second terminals of said first, second, fourth and sixth switching means each snubbing circuit including a resistor having first and second terminals, a snubbing diode having a first terminal connected to said first terminal of said resistor, and a second terminal connected to said second terminal of said resistor, and a snubbing capacitor connected to said first terminals of said resistor and snubbing diode.

Claim 11

A circuit as in claim 6 further including a further capacitor connected between said first and third circuit terminals and a serially connected capacitor and resistor also connected between said first and third circuit terminals.

Claim 12

A circuit as in claim 6 further including a voltage source connected between said first and third circuit terminals and a load connected between said second and third circuit terminals.

Claim 13

A circuit as in claim 6 further including means for alternately applying a signal to the gate terminals of said first and second switching means to complete said current path so that said first and second switching means alternately conduct current for applying signals to the gate terminals of said fourth and fifth switching means following application of a signal to the gate terminal of said first switching means to back bias said first switching means and interrupt the current path through said first switching means and for applying signals to the gate terminals of said third and sixth switching means following application of a signal to the gate terminal of said second switching means to back bias said second switching means and interrupt the current path through said second switching means.

Claim 14

A circuit as in claim 6 further including: a multivibrator producing at an output thereof, a signal alternately shifting between a first and second electical condition, a delay circuit connected to the output of said multivibrator for receiving signal and producing a further signal alternately shifting between first and second electrical condition delayed in time with respect to the received signal, logic means connected to said delay circuit for receiving further signal, and producing a first enable signal when said further signal shifts from said first to second condition and a second enable signal when said further signal shifts from said second to said first condition, means connected to said logic means for receiving said second enable signal and for causing said second electronic switch means to be rendered conductive when said second enable signal is received, first flip-flop means connected to said delay circuit for receiving said further signal and for shifting from a first to second output condition when said further signal shifts from said first to said second condition, second flip-flop means connected to said delay circuit for receiving said further signal and for shifting from a first to second output condition when said further signal shifts from said second to said first condition, means connected to said first flip-flop means for causing said first flip-flop means to shift from said second to said first output condition a given time following shift of said first flip-flop means from said first to said second condition, and means connected to said second flip-flop means for causing said second flip-flop means to shift from said second to said first output condition a given time following shift of said second flip-flop means from said first to said second condition.

Claim 15

A circuit as in claim 13 further including means connected to said first flip-flop means for causing said first electronic switching means to be rendered non-conductive when said first flip-flop means shifts from said second to said first output condition and means connected to said second flip-flop means for causing said second electronic switching means to be rendered non-conductive when said second flip-flop means shifts from said second to said first output condition.

Claim 16

A cirvuit as in claim 14 further including: means for receiving an enable signal, delay circuit means for receiving said enable signal and producing a delayed enable signal, futher delay circuit means for receiving said delayed enable signal and produced a further delayed enable signal, logic means connecting said further delay circuit means to said means for causing said first switching means to be rendered conductive and to said means for causing said second switching means to be rendered conductive for preventing said first and second switching means from being rendered conductive until said further delay circuit means produces said further delayed signal, and logic means connecting said delay circuit means to said means for causing said first switching means to be rendered non-conductive and to said means for causing said second switching means to be rendered non-conductive for preventing said first and second switching means from being rendered non-conductive.

Claim 17

A circuit as in claim 13 further including logic means connected to said first flip-flop means and to the output of said multivibrator for receiving said signal at the output thereof and for causing said first flip-flop means to shift from said second to said first output condition when said signal received from said multivibrator shifts from said first to said second condition if said first flip-flop means has not previously been shifted from said first to second output condition and logic means connecting said second flip-flop means to the output of said multivibrator for receiving said signal at the output thereof and for causing said second flip-flop means to shift from said second to said first output condition when said signal received from said multivibrator shifts from said second to said first output condition if said second flip-flop means has not previously been shifted from said first to second output condition.

Claim 18

A circuit as in claim 13 wherein each said means shift from a second to first condition and includes means for comparing first and second electrical signals and producing a signal to cause said flip-flop connected to that causing means to shift from said second to said first output condition when the compared signals differ by a predetermined amount.

Claim 19

A circuit as in claim 17 wherein each said means for causing a flip-flop means to shift from a second to first condition includes an operational amplifier.

Claim 20

A system as in claim 1 further includes means for preveNting said switch means from connecting said chopper circuit means in any configuration except said second configuration so long as said terminals of said storage means are connected to said external source.

Claim 21

A system as in claim 19 wherein said preventing means includes a switch having a first position when said terminals are connected to said source and a second position when said terminals are not connected to said source.

Claim 22

A system as in claim 20 wherein said switch means includes a plurality of relays each having at least a single controlled switch, logic means for controlling said relays to connect said chopper in said first, second and third configurations and a logic voltage source for supplying energy to said relays and logic means connected to said switch of said preventing means and wherein said preventing means further includes means for connecting at least some relays to said switch of said preventing means so that those relays are disconnected from said logic voltage source when said switch of said preventing means is in said first position.

Claim 23

Apparatus as in claim 1 further includes means for controlling the charging rate when said chopper circuit means is in said second configuration.

Claim 24

Apparatus as in claim 22 wherein said controlling means includes means for providing a signal which varies as a function of the gas pressure in said storage menas and means for controlling the rate of charging as a function of said signal.

Claim 25

Apparatus as in claim 23 wherein said controlling means further includes means for preventing further charging after said storage means is completely charged.

Claim 26

A system as in claim 1 further including means for producing a first signal which varies as a function of the position of said manual control means, means for producing a second signal which varies as a function of motor current, means for comparing said first and second signals and producing a further signal which varies as a function of the difference between said first and second signal, further switch means having a first position connecting said storage means directly to said motor and a second position not connecting said storage means to said motor and means for causing said further switch means to shift from said second to first position when said further signal reaches a given value.

Claim 27

A system as in claim 2 further including: first switch means having a first output condition when said manual control means is being operated and a second output condition when said manual control means is not being operated, second switch means having a first output condition when a brake is being manually operated and a second output condition when that brake is not being manually operated, third switch means having a first output condition when said storage means is receiving electrical energy from an external source and a second output condition when said storage means is not receiving electrical energy from an external source, and logic means connected to said first, second and third switch means and to said switch means connecting said switch means in said configuration for controlling the configuration and mode in which said chopper circuit is connected.

Claim 28

A system as in claim 26 further including fourth switch means having a first output condition when said vehicle is moving forward and a second output condition when said vehicle is moving backwards.

Claim 31

An electrical power control system for an electrically powered vehicle having a motor for driving the vehicle along the earth''s surface, manual control means for varying the speed of the vehicle, electrical energy storage means having terminals for producing a direct current output voltage and for receiving electrical energy to recharge said storage means and means for receiving energy from an external voltage source comprising: chopper circuit means for receiving at one terminal an input direct current voltage and producing at a second terminal a direct current voltage output including means for controlling the magnitude of said direct current output voltage, switch means for connecting said chopper circuit between said terminals of electrical energy storage means and said motor for supplying electrical energy to said motor to drive said vehicle along the earth''s surface, further switch means having a first position connecting said storage means directly to said motor and a second position not connecting said storage means to said motor, and logic means for causing said further switch means to shift from said second to first position when the speed called for by said manual control means exceeds the actual speed of said vehicle by a predetermined amount.

Claim 32

An electrical power control system for an electrically powered vehicle having a motor for driving the vehicle along the earth''s surface, manual control means for varying the speed of the vehicle, electrical energy storage means having terminals for producing a direct current output voltage and for receiving electrical energy to recharge said storage means and means for receiving energy from an external voltage source comprising: chopper circuit means for receiving at one terminal an input direct current voltage and producing at a second terminal a direct current voltage output including means for controlling the magnitude of said direct current output voltage, switch means for connecting said chopper circuit between said terminals of electrical energy storage means and said motor for supplying electrical energy to said motor to drive said vehicle along the earth''s surface, further switch means having a first position connecting said storage means directly to said motor and a second position not connecting said storage means to said motor, and logic means for causing said further switch means to shift from said second to first position when the speed called for by said manual control means exceeds the actual speed of said vehicle by a predetermined amount.

Claim 33

A system as in claim 29 wherein said chopper circuit includes: first electronic switching means having first and second switch terminals and a gate terminal so that a current path is completed between said first and second terminals when a given voltage signal is applied to said gate terminal and is interruped when a given back bias voltage is applied between said first and second terminals, second electronic switching means having first and second switch terminals and a gate terminal so that a current path is completed between said first and second terminals when a given voltage signal is applied to said gate terminal and is interrupted when a given back bias voltage is applied between said first and second terminals, third electronic switching means having first and second switch terminals and a gate terminal so that a current path is completed between said first and second terminals when a given voltage signal is applied to said gate terminal, means for connecting said first terminal of said first switching means to said first terminal of said third switching means, fourth electronic switching means having first and second switch terminals and a gate terminal so that a current path is completed between said first and second terminals when a given voltage signal is applied to said gate terminal, means for connecting said second terminal of said fourth switching means to said second terminal of said first switching means, fifth electronic switching means having first and second switch terminals and a gate terminal so that a current path is completed between said first and second terminals when a given voltage signal is applied to said gate terminals, means for connecting said first terminal of said second switching means to said first terminal of said fifth switching means, sixth electronic switching means having first and second switch terminals and a gate terminal so that a current path is completEd between said first and second terminals when a given voltage signal is applied to said gate terminal, and means for connecting said second terminal of said second switching means to said second terminal of said sixth switching means,

Claim 34

A system as in claim 30 further including: means for connecting together said first terminals of said first, second, fifth and sixth switching means to define a first, second, fifth and sixth switching means to define a first circuit terminal, a first inductor having first and second terminals, means for connecting said first terminal of said first inductor to said second terminals of said first and fourth switching means, a second inductor having first and second terminals, means for connecting said first terminal of said second inductor to said second terminals of said second and sixth switching means, means for connecting together said second terminals of said first and second inductors to define a second circuit terminal, a capacitor having first and second terminals, means for connecting said first terminal of said capacitor to said first terminal of said fourth switching means and said second terminal of said third switching means, and means for connecting said second terminal of said capacitor to said first terminal of said sixth switching means and said second terminal of said fifth switching means, a first diode having first and second terminals, means for connecting said first terminal of said first diode to said first terminal of said first inductor, a second diode having first and second terminals, means for connecting said first terminal of said second diode to said first terminal of said second inductor, and means for connecting said second terminals of said first and second diodes to define a third circuit terminal.

Claim 35

A system as in claim 31 wherein said means for connecting said first terminal of said second inductor to said second terminals of said second and sixth switching means includes a third inductor and wherein said means for connecting said first terminal of said first inductor to said second terminals of said first and fourth switching means includes a fourth inductor.

Claim 36

A system as in claim 31 further including a snubbing circuit connected between the first and second terminals of said first, second, fourth and sixth switching means each snubbing circuit including a resistor having first and second terminals, a snubbing diode having a first terminal connected to said first terminal of said resistor and a second terminal connected to said second terminal of said resistor, and a snubbing capacitor connected to said first terminals of said resistor and snubbing diode.

Claim 37

A system as in claim 31 further including a further capacitor connected between said first and third circuit terminals and a serially connected capacitor and resistor also connected between said first and third circuit terminals.

Claim 38

A system as in claim 34 further including means ofr alternately applying a signal to the gate terminals of said first and second switching means to complete said current path so that said first and second switching means alternately conduct current for applying signals to the gate terminals of said fourth and fifth switching means following application of a signal to the gate terminal of said switching means to back bias said first switching means and interrupt the current path through said first switching means and for applying signals to the gate terminals of said third and sixth switching means following application of a signal to the gate terminal of said second switching means to back bias said second switching means and interrupt the current path through said second switching means.

Claim 39

A system as in claim 31 comprising: a multivibrator producing at an output thereof, a signal alternately shifting between a first and second electrical condition. a delay circuit connected to the output of said multivibrator for receiving signal and producing a further signal alternately shifting between first and second electrical condition delayed in time with respect to the received signal, logic means connected to said delay circuit for receiving further signal, and producing a first enable signal when said further signal shifts from said first to second condition and a second enable signal when said further signal shifts from said second to said first condition, means connected to said logic means for receiving said second enable signal and for causing said second electronic switch means to be rendered conductive when said second enable signal is received, first flip-flop means connected to said delay circuit for receiving said further signal and for shifting from a first to second output condition when said further signal shifts from said first to said second condition, second flip-flop means connected to said delay circuit for receiving said further signal and for shifting from a first to second output condition when said further signal shifts from said second to said first condition, means connected to said first flip-flop means for causing said first flip-flop means to shift from said second to said first output condition a given time following shift of said first flip-flop means from said second condition, and means connected to said second flip-flop means for causing said second flip-flop means to shift from said second to said first output condition a given time following shift of said second flip-flop means from said first to said second condition.

Claim 40

A system as in claim 36 further including means connected to said first flip-flop means for causing said first electronic switch means to be rendered non-conductive when said first flip-flop means shifts from said second to said first output condition and means connected to said second flip-flop means for causing said second electronic switch to be rendered non-conductive when said second flip-flop means shifts from said second to said first output condition.

Claim 41

A circuit as in claim 37 further including: means for receiving an enable signal, delay circuit means for receiving said enable signal and producing a delayed enable signal, further delay circuit means for receiving said delayed enable signal and produced a further delayed enable signal, and logic means connecting said delay circuit means to said means for causing said first switch to be rendered non-conductive and to said means for causing said second switch to be rendered non-conductive for preventing said first and second switches from being rendered non-conductive.

Claim 42

A circuit as in claim 36 further including logic means connected to said first flip-flop means and to the output of said multivibrator for receiving said signal at the output thereof and for causing said first flip-flop means to shift from said second to said first output condition when said signal received from said multivibrator shifts from said first to said second condition if said first flip-flop means has not previously been shifted from said first to second output condition and logic means connecting said second flip-flop means to the output of said multivibrator for receiving said signal at the output thereof and for causing said second flip-flop means to shift from said second to said first output condition when said signal received from said multivibrator shifts from said second to said first output condition if said second flip-flop means has not previously been shifted from said first to second output condition.

Claim 43

An electrical power control system for an electrically powered vehicle having a motor for driving the vehicle along the earth''s surface, manual control means for varying the speed of the vehicle, electrical energy storage means having terminals for producing a direct current output voltage and for receiving electrical energy to recharge said storage means and means for receiving energy from an external voltage source comprisinG: chopper circuit means for receiving at one terminal an imput direct current voltage and producing at a second terminal a direct current voltage output including means for controlling the magnitude of said direct current output voltage, switch means for connecting said chopper circuit between said terminals of said electrical energy storage means and said motor for supplying electrical energy to said motor to drive said vehicle along the earth''s surface, means for producing a first signal which varies as a function of the position of said manual control means, means for producing a second signal which varies as a function of motor current, means for comparing said first and second signals and producing a further signal which varies as a function of the difference between said first and second signals, and means for controlling said chopper circuit, to control energy transfer, as a function of said further signal.

Claim 44

An electrical power control system for an electrically powered vehicle having a motor for driving the vehicle along the earth''s surface, manual control means for varying the speed of the vehicle, electrical energy storage means having terminals for producing a direct current output voltage and for receiving electrical energy to recharge said storage means and means for receiving energy from an external voltage source comprisinG: chopper circuit means for receiving at one terminal an imput direct current voltage and producing at a second terminal a direct current voltage output including means for controlling the magnitude of said direct current output voltage, switch means for connecting said chopper circuit between said terminals of said electrical energy storage means and said motor for supplying electrical energy to said motor to drive said vehicle along the earth''s surface, means for producing a first signal which varies as a function of the position of said manual control means, means for producing a second signal which varies as a function of motor current, means for comparing said first and second signals and producing a further signal which varies as a function of the difference between said first and second signals, and means for controlling said chopper circuit, to control energy transfer, as a function of said further signal.

Claim 45

A system as in claim 40 wherein said chopper circuit includes: first electronic switching means having first and second switch terminals and a gate terminal so that a current path is completed between said first and second terminals when a given voltage signal is applied to said gate terminal and is interrupted when a given back bias voltage is applied between said first and second terminals, second electronic switching means having first and second switch terminals and a gate terminal so that a current path is completed between said first and second terminals when a given voltage signal is applied to said gate terminal and is interrupted when a given back bias voltage is applied between said first and second terminals, third electronic switching means having first and second switch terminals and a gate terminal so that a current path is completed between said first and second terminals when a given voltage signal is applied to said gate terminal, means for connecting together said first terminal of said first switching means to said first terminal of said third switching means, fourth electronic switching means having first and second switch terminals and a gate terminal so that a current path is completed between said first and second terminals when a given voltage signal is applied to said gate terminal, means for connecting said second terminal of said fourth switching means to said second terminal of said first switching means, fifth electronic switching means having first and second switch terminals and a gate terminal so that a current path is completed between said first and second terminals when a given voltage signal is applied to said gate terminals, means for connecting said first terminal of said second switching means to said first terminal of said fifth switching means, sixth electronic switching means having first and second switch terminals and a gate terminal so that a current path is completed between said first and second terminals when a given voltage signal is applied to said gate terminal, means for connecting said second terminal of said second switching means.

Claim 46

A system as in claim 41 further including: means for connecting together said first terminals of said first, second, fifth and sixth switching means to define a first circuit terminal, a first inductor having first and second terminals, means for connecting said first terminal of said first inductor to said second terminals of said first and fourth switching means, a second inductor having first and second terminals, means for connecting said first terminal of said second inductor to said second terminals of said second and sixth switching means, means for connecting said second terminals of said first and second inductors to define a second circuit terminal, a capacitor having a first and second terminals means for connecting said first terminal of said capacitor to said first terminal of said fourth switching means and said second terminal of said third switching means, and means for connecting said second terminal of said capacitor to said first terminal of said sixth switching means and said second terminal of said fifth switching means, a first diode having first and second terminals, means for connecting said first terminal of said first diode to said first terminal of said first inductor, a second diode having first and second terminals, means for connecting said first terminal of said second diode to said first terminal of said second inductor, and means for connecting said second terminals of said first and second diodes to define a third circuit terminal.

Claim 47

A system as in claim 42 wherein said means for connecting said first terminal of said second inductor to said second terminals of said second and sixth switching means includes a third inductor and wherein said means for connecting said first terminal of said first inductor to said second terminals of said first and fourth switching means includes a fourth inductor.

Claim 48

A system as in claim 42 further including a snubbing circuit connected between the first and second terminals of said first, second, fourth and sixth switching means each snubbing circuit including a resistor having first and second terminals, a snubbing diode having a first terminal connected to said first terminal of said resistor and a second terminal connected to said second terminal of said resistor and a second terminal connected to said second terminal of said resistor, and a snubbing capacitor connected to said first terminals of said resistor and snubbing diode.

Claim 49

A system as in claim 42 further including a further capacitor connected between said first and third circuit terminals and a serially connected capacitor and resistor also connected between said first and third circuit terminals.

Claim 50

A system as in claim 42 further including a voltage source connected between said first and third circuit terminals and a load connected between said second and third circuit terminals.

Claim 51

A system as in claim 42 further including means for alternately applying a signal to the gate terminals of said first and second switching means to complete said current path so that said first and second switching means alternately conduct current for applying signals to the gate terminals of said fourth and fifth switching means following application of a signal to the gate terminal of said first switching means to back bias said first switching means and interrupt the current path through said first switching means and for applying signals to the gate terminals of said third and sixth switching means following application of a signal to the gate terminal of said second switching means to back bias said second switching means and interrupt the current path through said second switching means.

Claim 52

A system as in claim 42 further including: a multivibrator producing at an output thereof, a signal alternately shifting between a first and second electrical condition, a delay circuit connected to the output of said multivibrator for receiving signals and producing a further signal alternately shifting between first and second electrical condition delayed in time with respect to the received signal, logic means connected to said delay circuit for receiving further signal, and producing a first enable signal when said further signal shifts from said first to second condition and second enable signal when said further signal shifts from said second to said first condition, means connected to said logic means for receiving said second enable signal and for causing said second electronic switch means to be rendered conductive when said second enable signal is received, first flip-flop means connected to said delay circuit for receiving said further signal and for shifting from a first to second output condition when said further signal shifts from said first to said second condition, second flip-flop means connected to said delay circuit fOr receiving said further signal and for shifting fromma first to second output condition when said further signal shifts from said second to said first condition, means connected to said first flip-flop means for causing said first flip-flop means to shift from said second to said first output condition a given time following shift of said first flip-flop means from said first to said second condition, and means connected to said second flip-flop means for causing said second flip-flop means to shift from said second to said first output condition a given time following shift of said second flip-flop means from said first to said second condition.

Claim 53

A system as in claim 48 further including means connected to said first flip-flop means for causing said first electronic switching means to be rendered non-conductive when said first flip-flop means shifts from said second to said first output condition and means connected to said second flip-flop means for causing said second electronic switching means to be rendered non-conductive when said second flip-flop means shifts from said second to said first output condition.

Claim 54

A circuit as in claim 49 further including: means for receiving an enable signal, delay circuit means for receiving said enable signal and producing a delayed enable signal, futher delay circuit means for receiving said delayed enable signal and produced a further delayed enable signal, logic means connecting said further delay circuit means to said means for causing said first switching means to be rendered conductive and to said means for causing said second switching means to be rendered conductive for preventing said first and second switching means from being rendered conductive until said further delay circuit means produces said further delayed signal, and logic means connecting said delay circuit means to said means for causing said first switching means to be rendered non-conductive and to said means for causing said second switching means to be rendered non-conductive for preventing said first and second switching means from being rendered non-conductive.