Battery charger using a controlled scr to provide tapering charging characteristics

Claim 2

A circuit for charging a battery comprising: a source of current, a control circuit including a controlled electronic rectifier having at least an anode, a cathode, and a gate electrode, said anode being connected to said source of current, said cathode being adapted for connection in circuit with a battery, a sensing circuit for sensing the potential on a battery and providing a sensing signal when said potential is below a predetermined level, means coupled to said sensing circuit for providing a predetermined constant reference voltage thereto, said sensing signal being produced when said reference voltage is greater than said predetermined level, control means in circuit with said sensing circuit and with said controlled electronic rectifier for triggering the conduction of said controlled electronic rectifier in response to said sensing signal to cause charging of a battery at a rate inversely proportional to the amount of charge on the battery, and current-limiting means in circuit with said controlled electronic rectifier for limiting the charging rate to a battery, said current limiting means comprising: a transformer comprising a primary and a secondary, said primary being in circuit with the cathode of said controlled electronic rectifier; a potentiometer in circuit with the secondary of said transformer and comprising a load therefor, said potentiometer determining the maximum permissible current flow to a battery; and transistor means in circuit with said potentiometer and said control means for providing a signal to said control means to affect the conduction of said controlled electronic rectifier in such a manner that the charging rate is reduced when the charging rate to a battery in response to said sensing signal would otherwise be greater than said maximum permissible current flow.

Claim 3

In a control circuit of the type which comprises a first source of DC voltage, a controlled rectifier including an anode electrode and a cathode electrode which define a current path therebetween, said current path being in circuit with said first source, and a gate electrode for controlling the current flow in said path, and a battery in circuit with said current path, the improvement which comprises control means for controlling the current flow in said current path to a rate which causes charging of the battery at a rate inversely proportional to the charge on said battery, said control means including: sensing means in circuit with said battery for sensing the charge on said battery and providing a sensing signal indicative thereof, said sensing means including first transistor means capable of being rendered conductive to provide said sensing signal when the charge on said battery is below a predetermined level, conduction control means for causing said first transistor means to conduct when the charge on said battery is below said a a predetermined level, said conduction control means comprising a source of reference potential and variable resistance means in circuit with said source of reference potential and said first transistor means, gate control means in circuit with said first transistor means and said gate electrode for controlling the average current flow in said current path in response to the magnitude of the sensing signal from said transistor means, said gate control means including second transistor means in circuit with said first transistor means, charge storage means in circuit with said second transistor means, wherein said second transistor partially determines the rate of charge and discharge of said charge storage means, and unijunction transistor means in circuit with said charge storage means, said resistive means and said gate electrode of said controlled rectifier, said unijunction transistor means providing a control signal to said gate electrode in response to the rate of charge and discharge of said charge storage means, and current-limiting means in said current path for limiting the charging rate to said battery, said current-limiting means comprising transformer means in circuit with said controlled rectifier and fourth transistor means in circuit with said transformer means and said unijunction transistor means for partially controlling the rate of charge and discharge of said charge storage means to limit the charging rate to said battery.

Claim 4

In a control circuit of the type which comprises a first source of DC voltage, a controlled rectifier including an anode electrode and a cathode electrode which define a current path therebetween, said current path being in circuit with said first source, and a gate electrode for controlling the current flow in said path, and a battery in circuit with said current path, the improvement which comprises control means for controlling the current flow in said current path to a rate which causes charging of the battery at a rate inversely proportional to the charge on said battery, said control means including: sensing means in circuit with said battery for sensing the charge on said battery and providing a sensing signal indicative thereof, said sensing means including first transistor means capable of being rendered conductive to provide said sensing signal when the charge on said battery is below a predetermined level, conduction control means for causing said first transistor means to conduct when the charge on said battery is below said a a predetermined level, said conduction control means comprising a source of reference potential and variable resistance means in circuit with said source of reference potential and said first transistor means, gate control means in circuit with said first transistor means and said gate electrode for controlling the average current flow in said current path in response to the magnitude of the sensing signal from said transistor means, said gate control means including second transistor means in circuit with said first transistor means, charge storage means in circuit with said second transistor means, wherein said second transistor partially determines the rate of charge and discharge of said charge storage means, and unijunction transistor means in circuit with said charge storage means, said resistive means and said gate electrode of said controlled rectifier, said unijunction transistor means providing a control signal to said gate electrode in response to the rate of charge and discharge of said charge storage means, and current-limiting means in said current path for limiting the charging rate to said battery, said current-limiting means comprising transformer means in circuit with said controlled rectifier and fourth transistor means in circuit with said transformer means and said unijunction transistor means for partially controlling the rate of charge and discharge of said charge storage means to limit the charging rate to said battery.

Claim 5

A control circuit comprising the combination of: a first source of DC potential which includes a first terminal and a second terminal, a controlled rectifier including an anode electrode and a cathode electrode which define a current path therebetween said current path being in circuit with said first terminal of said first source of DC potential and a gate electrode for controlling the current flow in said path, and a battery including a first terminal in circuit with said current path and a second terminal in circuit with said second terminal of said first source of DC potential, and control meanS for controlling the current flow in said current path to a rate which causes charging of the battery at a rate inversely proportional to the charge on said battery, said control means including: sensing means in circuit with said battery for sensing the charge on said battery, said sensing means including a first transistor which is biased to be normally nonconductive and which is caused to conduct to provide a sensing signal when the charge on said battery is below a predetermined level, means for causing said first transistor to conduct at a predetermined level comprising a first source of reference potential, and variable resistance means in circuit with said first source of reference potential and the base of said first transistor means so that adjustment of said variable resistance means varies said predetermined level, gate control means in circuit with said first transistor means and said gate electrode for controlling the average current flow in said current path in response to the conduction of said transistor means, said gate control means including a second transistor in circuit with said first transistor for receiving said sensing signal and providing an output signal in response thereto, charge storage means in circuit with said second transistor for receiving said output signal, resistive means in circuit with said charge storage means and said second transistor for partially determining the rate of charge and discharge of said charge storage means, and unijunction transistor means in circuit with said charge storage means, said resistive means and said gate electrode of said controlled rectifier for providing a control signal to said gate electrode which is responsive to the rate of charge and discharge of said charge storage means, a first transformer coupling said first transistor to said second transistor, and a second source of DC potential isolated from said first source of DC potential, said first source of DC potential and said second source of DC potential being derived from a common source of AC potential.

Claim 6

A control circuit comprising the combination of: a first source of DC potential which includes a first terminal and a second terminal, a controlled rectifier including an anode electrode and a cathode electrode which define a current path therebetween said current path being in circuit with said first terminal of said first source of DC potential and a gate electrode for controlling the current flow in said path, and a battery including a first terminal in circuit with said current path and a second terminal in circuit with said second terminal of said first source of DC potential, and control meanS for controlling the current flow in said current path to a rate which causes charging of the battery at a rate inversely proportional to the charge on said battery, said control means including: sensing means in circuit with said battery for sensing the charge on said battery, said sensing means including a first transistor which is biased to be normally nonconductive and which is caused to conduct to provide a sensing signal when the charge on said battery is below a predetermined level, means for causing said first transistor to conduct at a predetermined level comprising a first source of reference potential, and variable resistance means in circuit with said first source of reference potential and the base of said first transistor means so that adjustment of said variable resistance means varies said predetermined level, gate control means in circuit with said first transistor means and said gate electrode for controlling the average current flow in said current path in response to the conduction of said transistor means, said gate control means including a second transistor in circuit with said first transistor for receiving said sensing signal and providing an output signal in response thereto, charge storage means in circuit with said second transistor for receiving said output signal, resistive means in circuit with said charge storage means and said second transistor for partially determining the rate of charge and discharge of said charge storage means, and unijunction transistor means in circuit with said charge storage means, said resistive means and said gate electrode of said controlled rectifier for providing a control signal to said gate electrode which is responsive to the rate of charge and discharge of said charge storage means, a first transformer coupling said first transistor to said second transistor, and a second source of DC potential isolated from said first source of DC potential, said first source of DC potential and said second source of DC potential being derived from a common source of AC potential.

Claim 7

The circuit as defined in claim 3 further including second transformer means for coupling said unijunction transistor means to said gate electrode.

Claim 8

A circuit for charging a battery comprising: a source of current including a source of AC potential, a first transformer in circuit with said source of AC potential, and a full-wave rectifier in circuit with said first transformer, a control circuit including an electronic rectifier having an anode, a cathode, and a gate electrode, said anode being in circuit with said full-wave rectifier, said cathode being adapted for connection in circuit with a battery wherein said sensing circuit for sensing the charge on a battery wherein said sensing means includes a first transistor which is normally biased to be nonconductive, and which is caused to conduct when the potential on a battery falls below a predetermined level, the level of conduction of said first transistor being proportional to the amount by which the potential on a battery is below the predetermined potential, said sensing circuit further including a second transformer means in circuit with said source of AC potential, and rectifier means for providing full-wave rectification of the signal at the output of the second transformer, means coupled to said sensing circuit for providing a predetermined constant reference voltage, third transformer means for coupling a control signal to said gate electrode, and control means in circuit with said sensing circuit and with said rectifier through said third transformer means for automatically controlling the conduction of said electronic rectifier to cause charging of a battery at a rate inversely proportional to the amount of charge on the battery.

Claim 9

A circuit for charging a battery comprising: a source of current including a source of AC potential, a first transformer in circuit with said source of AC potential, and a full-wave rectifier in circuit with said first transformer, a control circuit including an electronic rectifier having an anode, a cathode, and a gate electrode, said anode being in circuit with said full-wave rectifier, said cathode being adapted for connection in circuit with a battery wherein said sensing circuit for sensing the charge on a battery wherein said sensing means includes a first transistor which is normally biased to be nonconductive, and which is caused to conduct when the potential on a battery falls below a predetermined level, the level of conduction of said first transistor being proportional to the amount by which the potential on a battery is below the predetermined potential, said sensing circuit further including a second transformer means in circuit with said source of AC potential, and rectifier means for providing full-wave rectification of the signal at the output of the second transformer, means coupled to said sensing circuit for providing a predetermined constant reference voltage, third transformer means for coupling a control signal to said gate electrode, and control means in circuit with said sensing circuit and with said rectifier through said third transformer means for automatically controlling the conduction of said electronic rectifier to cause charging of a battery at a rate inversely proportional to the amount of charge on the battery.

Claim 10

The circuit as defined in claim 5 wherein said sensing circuit further comprises a voltage divider including a potentiometer in circuit with said first transistor, said potentiometer being adapTed for setting at a predetermined full-charge battery voltage so that said first transistor is nonconductive, and so that said first transistor conducts when the reference voltage is higher than the battery voltage.

Claim 11

The circuit as defined in claim 5 further including current-limiting means in circuit with said rectifier for limiting the charging rate to a battery.

Claim 12

The circuit as defined in claim 5 wherein said control means includes a phase shift circuit including a capacitor which controls the signal applied to the gate electrode of said rectifier.

Claim 13

The circuit as defined in claim 8 wherein said control means further includes a unijunction transistor in circuit with said capacitor and said gate electrode of said rectifier.

Claim 14

The circuit as defined in claim 5 wherein said sensing circuit further includes voltage divider means including spaced resistances and a potentiometer, said potentiometer being coupled to the base of said first transistor and to said source of reference potential.

Claim 15

The circuit as defined in claim 5 including means in said sensing circuit for protecting the sensing circuit from damage due to reversing the polarity of a battery applied to said sensing means.

Claim 16

The circuit as defined in claim 5 wherein said control means includes a second transistor, phase shift means comprising a capacitor in circuit with said second transistor to provide a pulse for triggering the gate of said rectifier upon energization by said sensing circuit.

Claim 17

The circuit in accordance with claim 5 wherein said reference voltage is maintained at a constant level by a Zener diode.