Battery charger
First Claim
1. A battery charger comprising:
- voltage converter means for converting a first-frequency alternating source voltage into a second-frequency alternating voltage and converting the second-frequency alternating voltage into a direct current voltage which appears at an output of the voltage converter means;
voltage controlled solid-state variable impedance means for connection between the output of the voltage converter means and a battery to be charged for controlling the flow of direct current from the output of the voltage converter means to the battery to effect charging thereof;
control means responsive to the battery voltage to provide a control voltage to said variable impedance means to charge the battery at a selected rate and to cease charging at a predetermined charge level;
the control means controls said variable impedance means to its OFF state when the voltage of the battery is below a selected value; and
wherein the variable impedance means includes a saturated region and a linear operating region in which the impedance thereof is controlled as a proportional function of the control voltage and further includes an OFF state in which the impedance is sufficiently high to cease the charging of the battery through the variable impedance means.
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Accused Products
Abstract
An isolated battery charger suitable for charging lead-acid batteries includes a high-frequency power conditioner that rectifies source current to a DC value and chops the current at a comparatively high frequency, e.g., 25 KHz, using a pair of MOSFET switches (138 and 140) to provide power pulses to the primary of a step-down transformer (T1). The output of the step-down transformer (T1) is presented to an enhancement mode MOSFET (206) in series circuit with the battery (B) to be charged with the gate bias of the MOSFET controlled in response to the sensed voltage of the battery to provide current to the battery as a function of its charge. Control circuitry is provided to limit charging to a small `trickle` level in the event the battery (B) is fully discharged to increase its charge level prior to initiating the full charge current. The provision of a voltage converter (100) operating at a relatively high frequency allows use of a lightweight and compact transformer (T1) that nonetheless provides a high current for charging.
97 Citations
28 Claims
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1. A battery charger comprising:
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voltage converter means for converting a first-frequency alternating source voltage into a second-frequency alternating voltage and converting the second-frequency alternating voltage into a direct current voltage which appears at an output of the voltage converter means; voltage controlled solid-state variable impedance means for connection between the output of the voltage converter means and a battery to be charged for controlling the flow of direct current from the output of the voltage converter means to the battery to effect charging thereof; control means responsive to the battery voltage to provide a control voltage to said variable impedance means to charge the battery at a selected rate and to cease charging at a predetermined charge level; the control means controls said variable impedance means to its OFF state when the voltage of the battery is below a selected value; and wherein the variable impedance means includes a saturated region and a linear operating region in which the impedance thereof is controlled as a proportional function of the control voltage and further includes an OFF state in which the impedance is sufficiently high to cease the charging of the battery through the variable impedance means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A battery charger comprising:
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means for providing a direct current voltage for charging a battery; voltage controlled solid-state variable impedance means for connection between the providing means and the battery to be charged for controlling the flow of current from the providing means to the battery to effect charging thereof; control means responsive to the battery voltage to provide a control voltage to said variable impedance to charge the battery at a selected rate and to cease charging at a predetermined charge level; wherein said variable impedance means is in series circuit with said battery and includes a saturated region and a linear operating region in which the impedance thereof is controlled as a proportional function of the control voltage and further includes an OFF state in which the impedance is sufficiently high to cease the charging of the battery, and wherein said control means controls said variable impedance means to its OFF state when the voltage of the battery is below a selected value. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25)
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26. A battery charger comprising:
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means for providing a direct current voltage for charging a battery; voltage controlled solid-state variable impedance means for connection between the providing means and the battery to be charged for controlling the flow of current from the providing means to the battery to effect charging thereof; control means responsive to the battery voltage to provide a control voltage to said variable impedance to charge the battery at a selected rate and to cease charging at a predetermined charge level, and a trickle current charge path for charging the battery when the variable impedance means is in its OFF state and the voltage of the battery is below a selected value. - View Dependent Claims (27, 28)
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Specification