Electricity: electrical systems and devices – Safety and protection of systems and devices – Voltage regulator protective circuits
Reexamination Certificate
2002-01-30
2004-08-17
Jackson, Stephen W. (Department: 2836)
Electricity: electrical systems and devices
Safety and protection of systems and devices
Voltage regulator protective circuits
C361S086000, C361S088000
Reexamination Certificate
active
06778365
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a charging circuit. More specifically, the present invention relates to a charging circuit, and method of implementing the same, that can be used in a defibrillator with a more efficient charge time.
2. Description of the Related Art
FIG. 1
illustrates a conventional charging system having a step-up voltage capability using two linked inductive windings, e.g., a transformer, primary winding
10
and secondary winding
12
, between a charging voltage source
20
and a utilization device
40
. This arrangement was disclosed in FIG. 1 of U.S. Pat. No. 4,070,699, to Einbinder. As set forth in U.S. Pat. No. 4,070,699, to charge capacitor
30
, switching circuit
14
is closed and voltage is applied across primary winding
10
. Switching circuit
14
is then opened and the energy accumulated in primary winding
10
is transferred to secondary winding
12
, charges capacitor
30
, which ultimately supplies voltage to utilization device
40
. Likewise, upon a closing of switching circuit
14
, energy transfers back from secondary winding
12
to primary winding
10
. Energy is basically in one winding at a time. U.S. Pat. No. 4,070,699 also notes that it is beneficial to prevent current in the circuit containing secondary winding
12
, diode
18
, and capacitor
30
from reaching a zero level, which would result in the flux density for primary and secondary windings
10
and
12
going to zero. The benefit of keeping the flux density between primary and secondary windings
10
and
12
sufficiently high is that greater power can be transferred between inductors
10
and
12
. To accomplish this, U.S. Pat. No. 4,070,699 recommends closing switching circuit
14
when current in the secondary winding
12
circuit drops to a predetermined level. Usually this level corresponds to the flux density for the primary and secondary windings dropping to two thirds of the saturation level.
Some recent charging systems allow the flux density between primary and secondary windings
10
and
12
to drop to zero by waiting a predetermined time before closing the switching circuit, this predetermined time is meant to correspond to a period of time at which the current flow in secondary winding
12
would typically have extinguished. Thus, though less efficient, recent charging systems typically allow current flow in secondary winding
12
to be extinguished since it is difficult to determine the current flow in secondary winding
12
without permeating noise into circuits connected to secondary winding
12
. Utilization device
40
could include delicate sensors for measuring vital health statistics of a patient, for example, when the charging system is for a defibrillator. Thus, recently it has become more important to have secondary winding
12
mostly isolated from primary winding
10
, rather than have a more efficient transfer of power between primary and secondary windings
10
and
12
. Magnetic field sensing circuit
16
, illustrated in
FIG. 1
, does not allow for such recently necessitated isolation between primary and secondary windings
10
and
12
. In addition, although isolation between primary and secondary windings
10
and
12
is important, most recent charging circuits do not have truly isolated primary and secondary windings
10
and
12
since they attempt to sample the voltage in the secondary winding circuitry using a resistor bridge between the circuits connected to primary and secondary windings
10
and
12
, which in actuality is not an isolation of primary and secondary windings
10
and
12
, though the resistor bridge is designed to minimize cross talk between the circuits connected to primary and secondary windings
10
and
12
as much as possible.
Thus, what is needed is an improved charging system that has a more efficient transfer of power and a truly isolated primary and secondary sides.
SUMMARY OF THE INVENTION
To solve the above and other aspects, it is an object of the present invention to provide an improved charging circuit, and method for implementing the same, including a primary switching circuit that controls the transfer of energy between windings in a transformer based upon a reconstruction of a secondary winding current, using a voltage across a primary winding of the transformer, without directly sampling the secondary winding current.
A further object of the present invention is to provide a charging circuit having a transformer having at least primary and secondary windings and a switch to cease an energy transfer between the primary and secondary windings based upon a reconstruction of an unsampled energy level in the secondary winding.
Another object of the present invention is to provide a charging circuit having a transformer having at least primary and secondary windings and a switch to cease an energy transfer between the primary and secondary windings based upon a reconstruction of an unsampled energy level in the secondary winding, wherein the switch ceases the energy transfer when the reconstructed energy level in the secondary winding is a current indicating that a flux density in the transformer has lowered to a predetermined flux density level.
An additional object of the present invention is to provide a charging circuit having a transformer including at least primary and secondary windings and a switch to control a charging of the primary winding until an energy level in the primary winding reaches a predetermined charging level and to control a transfer of energy between the primary and secondary winding until a reconstructed energy level, of an unsampled energy level in the secondary winding, indicates that that a flux density of the transformer has lowered to a predetermined flux density level.
An additional object of the present invention is to provide a charging circuit having a transformer including at least primary and secondary windings and a switch to control a charging of the primary winding until an energy level in the primary winding reaches a predetermined charging level and to control a transfer of energy between the primary and secondary winding until a reconstructed energy level, of an unsampled energy level in the secondary winding, indicates that that a flux density of the transformer has lowered to a predetermined flux density level, wherein the reconstructed energy level is generated by sampling a voltage representative of a voltage across the primary winding and integrating the sampled voltage.
Another object of the present invention is to provide a charging method, including charging a primary winding of a transformer until an energy level of the primary winding reaches a predetermined charge level, and transferring energy between the primary winding and a secondary winding of the transformer until a reconstructed energy level, of an unsampled energy level of the secondary winding, reaches a predetermined energy level.
Another object of the present invention is to provide a charging method, including charging a primary winding of a transformer until an energy level of the primary winding reaches a predetermined charge level, transferring energy between the primary winding and a secondary winding of the transformer until a reconstructed energy level, of an unsampled energy level of the secondary winding, reaches a predetermined energy level, initiating the charging of the primary winding after the transferring of energy between the primary winding and the secondary winding has ceased, and repeating the charging of the primary winding, the transferring of the energy between the primary winding and the secondary winding, and the initiating of the charging of the primary winding until a total charge amount is accumulated in a circuit connected to the secondary winding.
These together with other aspects and advantages which will be subsequently apparent, reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein l
Jackson Stephen W.
Nguyen Danny
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