Circuit arrangement for charging rechargeable batteries
First Claim
1. A circuit arrangement for charging rechargeable batteries, comprising:
- a first terminal and a second terminal to which at least one battery is connectable in order to be charged, a charging current source connected to both terminals and adapted to supply thereto charging current pulse trains, said current source having a control input to which a pulse-shaped control signal can be applied to enable and to inhibit the supply of a charging current pulse train, and wherein the current source, in accordance with the pulse-shaped control signal applied to its control input, supplies to the at least one battery the charging current pulse train of charging current pulses which occur during successive charging periods which are spaced from one another by charging pauses, whereinthe first terminal of the circuit arrangement is coupled to an input of a first detection device which receives a voltage which is proportional to a sum voltage at the first terminal and comprising the battery no-load voltage and a pulse-shaped charging voltage which is superposed on said battery no-load voltage and which is proportional to the charging current pulses via the internal resistance of the battery, and to derive an actual voltage proportional to an average sum voltage, which comprises the battery no-load voltage and the average-value voltage superposed on said battery no-load voltage and resulting from the pulse-shaped charging voltage, wherein the first detection device detects the actual voltage dependent upon a variable reference voltage available in the first detection device, and generates at its output a detection signal which corresponds to the detection result and depends on the actual voltage and on the reference voltage,means coupling the output of the first detection device to an input of a control pulse generator for generating the pulse-shaped control signal, the detection signal enabling said control pulse generator to control the duty cycle of the pulse-shaped control signal generated by said control pulse generator at an output thereof,second means coupling the output of the control pulse generator to the control input of the charging current source to enable or inhibit the supply of a charging current pulse train, andfor an increasing actual voltage or a decreasing reference voltage in the first detection device the control pulse generator, dependent on the detection signal applied to its input, varies the duty cycle the pulse-shaped control signal which it can generate such that the charging current source reduces the ratio between the charging period and the charging pause in the charging current pulse train, andmeans for varying the reference voltage available in the first detection device in the same sense as the duty cycle of the pulse-shaped control signal at the output of the control pulse generator dependent on said duty cycle.
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Abstract
A circuit arrangement for charging batteries comprises a charging current source for supplying charging current pulse trains. The circuit arrangement comprises a first detection device for determining an actual voltage dependent upon a variable reference voltage, which actual voltage is proportional to the average sum voltage of a battery. The first detection device supplies a detection signal corresponding to the detection result and which controls the duty cycle of the pulse-shaped control signal which can be generated by a control pulse generator. The control pulse generator varies the duty cycle dependent on the detection signal when the actual voltage increases or the reference voltage decreases, in a manner such that the ratio between the charging period and the charging pause in a charging pulse train is reduced. A device is provided which enable the reference voltage to be varied in the same sense as the duty cycle depending on this duty cycle.
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Citations
14 Claims
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1. A circuit arrangement for charging rechargeable batteries, comprising:
- a first terminal and a second terminal to which at least one battery is connectable in order to be charged, a charging current source connected to both terminals and adapted to supply thereto charging current pulse trains, said current source having a control input to which a pulse-shaped control signal can be applied to enable and to inhibit the supply of a charging current pulse train, and wherein the current source, in accordance with the pulse-shaped control signal applied to its control input, supplies to the at least one battery the charging current pulse train of charging current pulses which occur during successive charging periods which are spaced from one another by charging pauses, wherein
the first terminal of the circuit arrangement is coupled to an input of a first detection device which receives a voltage which is proportional to a sum voltage at the first terminal and comprising the battery no-load voltage and a pulse-shaped charging voltage which is superposed on said battery no-load voltage and which is proportional to the charging current pulses via the internal resistance of the battery, and to derive an actual voltage proportional to an average sum voltage, which comprises the battery no-load voltage and the average-value voltage superposed on said battery no-load voltage and resulting from the pulse-shaped charging voltage, wherein the first detection device detects the actual voltage dependent upon a variable reference voltage available in the first detection device, and generates at its output a detection signal which corresponds to the detection result and depends on the actual voltage and on the reference voltage, means coupling the output of the first detection device to an input of a control pulse generator for generating the pulse-shaped control signal, the detection signal enabling said control pulse generator to control the duty cycle of the pulse-shaped control signal generated by said control pulse generator at an output thereof, second means coupling the output of the control pulse generator to the control input of the charging current source to enable or inhibit the supply of a charging current pulse train, and for an increasing actual voltage or a decreasing reference voltage in the first detection device the control pulse generator, dependent on the detection signal applied to its input, varies the duty cycle the pulse-shaped control signal which it can generate such that the charging current source reduces the ratio between the charging period and the charging pause in the charging current pulse train, and means for varying the reference voltage available in the first detection device in the same sense as the duty cycle of the pulse-shaped control signal at the output of the control pulse generator dependent on said duty cycle. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- a first terminal and a second terminal to which at least one battery is connectable in order to be charged, a charging current source connected to both terminals and adapted to supply thereto charging current pulse trains, said current source having a control input to which a pulse-shaped control signal can be applied to enable and to inhibit the supply of a charging current pulse train, and wherein the current source, in accordance with the pulse-shaped control signal applied to its control input, supplies to the at least one battery the charging current pulse train of charging current pulses which occur during successive charging periods which are spaced from one another by charging pauses, wherein
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8. A battery charge circuit comprising:
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first and second terminals for connection to a battery to be charged, a charge current source coupled to said first and second terminals to supply a charge current pulse train thereto, said charge current source having a control input for receipt of a pulse-shaped control signal to enable and inhibit the supply of the charge current pulse train, a first detection device having an input coupled to said first terminal to receive a sum voltage determined by the no-load voltage of a connected battery and a pulse-shaped charge voltage superimposed on said no-load voltage and determined by charge current pulses flowing through the battery internal resistance, wherein said first detection device derives an actual voltage dependent upon a variable reference voltage and an average sum voltage of the battery to produce at an output thereof a detection signal which depends on the actual voltage and the reference voltage, first means coupling the output of the first detection device to an input of a control pulse generator which generates a pulse-shaped control signal having a duty cycle determined by said detection signal, second means coupling said pulse-shaped control signal to the control input of the charge current source, and means responsive to said pulse-shaped control signal for varying said reference voltage in the same sense that the duty cycle of the pulse-shaped control signal is varied, and wherein the control pulse generator, dependent on the detection signal, varies the duty cycle of the pulse-shaped signal it generates so that, for an increase of the actual voltage or a decrease in the reference voltage, the charge current source in response thereto reduces the ratio of the charge period to a charge interruption interval of the charge current pulse train. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification