Automatic rate control for defibrillator capacitor charging
First Claim
1. A control circuit for altering a voltage measure of current flow in a circuit line, said voltage measure being used by a current regulating circuit that controls the current flow from a battery through said circuit line in response to said voltage measure, said control circuit comprising:
- (a) a first summing circuit having an additive input and a subtractive input, wherein a reference voltage is present at said additive input and the voltage of said battery is present at said subtractive input, said first summing circuit thereby producing a difference voltage of the battery voltage subtracted from the reference voltage;
(b) a diode having an anode terminal and a cathode terminal, wherein said difference voltage is present at the anode terminal of the diode; and
(c) a second summing circuit having a first additive input and a second additive input wherein the voltage at the cathode terminal of said diode is present at the first additive input, and said voltage measure of current flow in said circuit line is present at the second additive input, said second summing circuit thereby producing an altered voltage measure that includes said voltage measure of current flow and said voltage present at the cathode terminal of said diode, said altered voltage measure being provided to the current regulating circuit for controlling the current flow from the battery.
10 Assignments
0 Petitions
Accused Products
Abstract
A control circuit ideally suited for a capacitor charging circuit (100) that uses an apparent measure of current flow through a circuit line to regulate current drawn from a battery through the circuit line is disclosed. A summing circuit (136) produces a difference voltage (138) of the battery voltage (152) subtracted from a threshold reference voltage (151). The difference voltage (138) is subsequently amplified by an amplifier (140), rectified by a diode (142), and added to a voltage measure (130) from a current-sense resistor (117) by a summing circuit (128). The resulting voltage measure (126) is an apparent measure of current flow and is provided to a charge controller (122) which regulates current flow through a transformer (107) by controlling the operation of a switch (108). As the voltage on the battery (102) decreases below the reference voltage set by voltage source (150), the increasing difference voltage (138) adds bias to the actual measure of current flow (130), thus providing the charge controller (122) with an apparent measure of current flow through the transformer (107) that is higher than the actual level of current flow. The charge controller is thereby deceived and reduces the current drawn from the battery through the transformer.
-
Citations
12 Claims
-
1. A control circuit for altering a voltage measure of current flow in a circuit line, said voltage measure being used by a current regulating circuit that controls the current flow from a battery through said circuit line in response to said voltage measure, said control circuit comprising:
-
(a) a first summing circuit having an additive input and a subtractive input, wherein a reference voltage is present at said additive input and the voltage of said battery is present at said subtractive input, said first summing circuit thereby producing a difference voltage of the battery voltage subtracted from the reference voltage; (b) a diode having an anode terminal and a cathode terminal, wherein said difference voltage is present at the anode terminal of the diode; and (c) a second summing circuit having a first additive input and a second additive input wherein the voltage at the cathode terminal of said diode is present at the first additive input, and said voltage measure of current flow in said circuit line is present at the second additive input, said second summing circuit thereby producing an altered voltage measure that includes said voltage measure of current flow and said voltage present at the cathode terminal of said diode, said altered voltage measure being provided to the current regulating circuit for controlling the current flow from the battery. - View Dependent Claims (2, 3, 4, 5)
-
-
6. A capacitor charger comprising:
-
(a) a battery; (b) a step-up transformer having a primary winding and a secondary winding, wherein said primary winding is connected to said battery; (c) a diode connected to said secondary winding; (d) a capacitor connected to said diode; (e) a current sensor for sensing current flowing through said primary winding; (f) a switch connected in series between said primary winding and said current sensor; and (g) control circuitry including; (i) a charge controller having an input to receive a voltage measure of current flow and an output connected to said switch, wherein said charge controller causes said switch to periodically conduct and interrupt current flow through said primary winding in response to the voltage measure of current flow received at said input; (ii) a first summing circuit having an additive input and a subtractive input wherein a reference voltage is present at the additive input and the voltage of said battery is present at the subtractive input, said first summing circuit thereby producing a difference voltage equal to the battery voltage subtracted from the reference voltage; (iii) a diode having an input and an output, wherein said difference voltage is present at the input of said diode; and (iv) a second summing circuit having a first and second additive input, wherein the voltage at the output of said diode is present at the first additive input, and a voltage produced by said current sensor is present at the second additive input, said second summing circuit combining the voltages present at the first and second additive inputs and producing the voltage measure of current flow received at said input of said charge controller. - View Dependent Claims (7, 8)
-
-
9. A method of controlling the rate of charge of a capacitor in a capacitor charging circuit, wherein said capacitor charging circuit includes a charge controller for controlling current flow from a battery through a transformer connected to the capacitor, said charge controller controlling current flow in response to an apparent measure of current flow through the transformer, said method comprising:
-
(a) producing a difference voltage by subtracting the voltage of the battery from a reference voltage; (b) producing said apparent measure of current flow by adding said difference voltage to a voltage representative of current flow through the transformer; and (c) providing said apparent measure of current flow to said charge controller for controlling current flow through the transformer. - View Dependent Claims (10)
-
-
11. A circuit for controlling a rate at which an energy storage capacitor is charged from a battery, comprising:
-
(a) a step-up transformer having a primary winding coupled to the battery and a secondary winding coupled to the energy storage capacitor; (b) a switch that is selectively closed to draw current from the battery through the primary winding of the step-up transformer; (c) a current sensor that produces a signal indicative of a level of current flowing through the primary winding when the switch is closed; (d) a charging circuit that monitors a voltage on the energy storage capacitor and selectively opens and closes the switch until a predetermined voltage on the energy storage capacitor is reached; and (e) a comparison circuit that compares a voltage on the battery with a reference voltage, the comparison circuit producing an output that is coupled to the charging circuit to cause the charging circuit to adjust the rate at which the energy storage capacitor is charged. - View Dependent Claims (12)
-
Specification