Constant power dissipation control of a linear pass element used for battery charging
First Claim
1. A control system for maintaining constant power dissipation of a linear pass element of a battery charger for charging a battery, comprising:
- a current sensor coupled to sense the charge current of the battery;
a voltage sensor coupled to sense the voltage of the linear pass element; and
an amplifier coupled to said current sensor and said voltage sensor for controlling the linear pass element so that the power dissipation of the linear pass element remains relatively constant.
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Accused Products
Abstract
A battery charger including a control system for controlling a linear pass element to maintain relatively constant power dissipation of the linear pass element. In one embodiment, the charge current and the voltage across the linear pass element are provided to a constant dissipation amplifier, which increases the charge current as the voltage of the linear pass element decreases due to charging of the battery. The charge current is increased in such a manner to maintain the power dissipation of the linear pass element to a relatively constant level. In another embodiment, the battery voltage is provided to the amplifier, which increases charge current in response to rising battery voltage to maintain constant power dissipation of the linear pass element. The latter embodiment is in recognition that the voltage across the linear pass element is inversely proportional to the voltage across the linear pass element. Furthermore, the power dissipation may be decreased towards the end of the charge cycle if a particular maximum charging current is desired, such as, for example, to maintain a trickle charge.
41 Citations
18 Claims
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1. A control system for maintaining constant power dissipation of a linear pass element of a battery charger for charging a battery, comprising:
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a current sensor coupled to sense the charge current of the battery; a voltage sensor coupled to sense the voltage of the linear pass element; and an amplifier coupled to said current sensor and said voltage sensor for controlling the linear pass element so that the power dissipation of the linear pass element remains relatively constant. - View Dependent Claims (2, 3, 4, 5)
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6. A control system for maintaining maximum power dissipation of a linear pass element of a battery charger for charging a battery receiving charge power from a relatively constant voltage source, comprising:
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a current sensor coupled to sense the charge current of the battery; a voltage sensor coupled to sense the battery voltage; and an amplifier coupled to said current sensor and said voltage sensor for controlling the linear pass element to increase the charge current as the battery voltage increases so that the power dissipation of the linear pass element remains relatively constant. - View Dependent Claims (7, 8)
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9. A battery charger for charging a battery, comprising:
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a voltage source for providing a relatively constant supply voltage; a linear pass element coupled in series with said voltage source and the battery for controlling charge current; a current sensor coupled to measure said charge current; a voltage sensor coupled to measure the voltage of the battery; and a control amplifier coupled to said current and voltage sensors and said linear pass element for increasing said charge current while the battery voltage increases so that the power dissipation of said linear pass element is maintained at or below a predetermined maximum level. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification