Battery voltage equalizer circuit
First Claim
1. A battery equalizer for equalizing the voltage of series connected batteries, the equalizer having a pair of distally opposite equalizer terminals for connection to the distally opposite battery terminals of the series batteries and an intermediate equalizer terminal for connection to an intermediate battery terminal of the series batteries, the equalizer comprising:
- (a) a full bridge having a first pair of opposite bridge nodes connected to the distally opposite equalizer terminals and having four legs defining a second pair of opposite, intermediate bridge nodes, each leg including an interposed power switching transistor connected for switching current through its leg, each transistor also having a switching control terminal;
(b) an autotransformer having opposite end terminals connected between said second pair of nodes and having a tap connected to said intermediate equalizer terminal; and
(c) a switching control circuit having outputs connected to the control terminal of each switching transistor and adapted to synchronously and alternatingly turn on the switching transistors of opposite legs of the bridge to connect said opposite end terminals of the autotransformer to said distally opposite equalizer terminals in alternating polarities.
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Accused Products
Abstract
A battery equalizer for equalizing the voltage on series connected batteries synchronously switches the opposite ends of a tapped autotransformer in alternately reversing connection to the distally opposite terminals of the battery by alternately turning transistor switches on and off in alternate pairs while maintaining a center tap of the autotransformer connected to an intermediate terminal of the series batteries. Switching is accomplished by power field effect transistors and a voltage converter converts the upper battery voltage to a floating voltage so that the voltages of the two batteries can be differenced. The differenced voltage provides an error signal for driving a pulse width modulator which switches the transistors. Two protective power switching field effect transistors are interposed in the circuit and connected to prevent damage to the circuitry in the event of misconnection.
61 Citations
20 Claims
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1. A battery equalizer for equalizing the voltage of series connected batteries, the equalizer having a pair of distally opposite equalizer terminals for connection to the distally opposite battery terminals of the series batteries and an intermediate equalizer terminal for connection to an intermediate battery terminal of the series batteries, the equalizer comprising:
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(a) a full bridge having a first pair of opposite bridge nodes connected to the distally opposite equalizer terminals and having four legs defining a second pair of opposite, intermediate bridge nodes, each leg including an interposed power switching transistor connected for switching current through its leg, each transistor also having a switching control terminal; (b) an autotransformer having opposite end terminals connected between said second pair of nodes and having a tap connected to said intermediate equalizer terminal; and (c) a switching control circuit having outputs connected to the control terminal of each switching transistor and adapted to synchronously and alternatingly turn on the switching transistors of opposite legs of the bridge to connect said opposite end terminals of the autotransformer to said distally opposite equalizer terminals in alternating polarities. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method for equalizing the voltages of storage batteries connected in series to have distally opposite battery terminals and at least one intermediate battery terminal, the method comprising:
synchronously switching the opposite ends of a tapped autotransformer in alternately reversing connection to the distally opposite terminals of the batteries by alternately turning transistor switches on and off in alternate pairs while maintaining a tap of the autotransformer connected to an intermediate terminal of the series batteries. - View Dependent Claims (19, 20)
Specification