Method and apparatus for low power, regulated output in battery powered electrotherapy devices
A device for controlling the discharge of a battery supplying an intermittent load, such as a nerve stimulation device. The device includes a controller which operates a switched inductor to feed a capacitor with numerous small pulses from the battery, thereby building up the charge and voltage on the capacitor, and occasionally discharging the capacitor to a load. The capacitor discharge is at higher current than the small pulses from the battery, so the battery is drained at small instantaneous discharge rates compared the too high instantaneous discharge current from the capacitor.
1. A circuit for maintaining consistent pulse output of a battery-powered apparatus to a load, said circuit comprising:
a battery having an electrical output;
an inductor, connected to the battery, for receiving the electrical output of the battery;
a capacitor, connected to the output of the inductor, for receiving and storing the electrical output of the inductor, the capacitor having an electrical output;
an electrode, connected to the capacitor, for delivering the electrical output to the load; and
a controller programmed to periodically connect and disconnect the inductor to the battery such that a plurality of current pulses are generated charging the capacitor, the controller is also programmed to intermittently connect and disconnect the capacitor to the load causing the capacitor to discharge the electrical output of the capacitor to the load, wherein the controller limits the pulses generated by the battery and the time between the pulses generated by the battery such that the resulting average electrical current draw from the battery is within the battery's optimal discharge rate.
2. The circuit of claim 1 further comprising a transformer, connected to the capacitor, for increasing the electrical output of the capacitor.
3. A device for providing a pulsed electrical stimulus to a nerve in the body of a patient, wherein said device is battery operated, said device comprising:
a battery having an electrical output;
an electrode, adapted for electrically contacting the body in the vicinity of such nerve to be stimulated, for delivering the electrical output to such nerve;
a capacitor, connected to the battery and the electrode, for storing the electrical output and delivering a electrical stimulus to such nerve;
a first switch, located between the capacitor and the electrode, for periodically connecting the capacitor to the electrode when the capacitor is sufficiently charged;
a second switch for periodically connecting and disconnecting the battery to and from the capacitor to incrementally charge the capacitor with a plurality of current pulses;
a controller programmed to operate the second switch to periodically connect and disconnect the battery to the capacitor, thereby incrementally transferring charge from the battery to the capacitor by supplying a plurality of current pulses to the capacitor, said controller being further programmed to periodically connect the capacitor to the electrode after a desired charge has been accumulated on the capacitor, to apply a pulsed electrical stimulus to the nerve, wherein the controller limits the pulses generated by the battery and the time between the pulses generated by the battery such that the resulting average electrical current draw from the battery is within the battery's optimal discharge rate.
4. The device of claim 3 further comprising a transformer, interposed between the capacitor and the electrodes, for increasing the electrical output of the capacitor.
5. A device for providing pulsed output from a battery, said device comprising:
a battery;
an electrical output terminal;
an electrical storage component operably and intermittently connected to the output terminal through a first switch means;
a second switch means, located between the battery and the electrical storage component, for connecting and disconnecting the battery to and from the electrical storage component;
control means programmed to intermittently operate the second switch thus transferring charge from the battery to the electrical storage component with a plurality of current pulses generated by the intermittent operation of the second switch, the control means is also programmed to intermittently connect the electrical storage component to the output terminal after a desired charge has been accumulated on the electrical storage component, wherein the control means limits the pulses generated by the battery and the time between the pulses generated by the battery such that the resulting average electrical current draw from the battery is within the battery's optimal discharge rate.
6. An apparatus for regulating the output of a battery to supply a load in a battery powered device comprising:
a switch;
an inductor having an output;
a capacitor being connected to the inductor and connected to the load through the switch, the conductor stores the output from the inductor and delivers the output to the load;
a controller programmed to operate the inductor by intermittently connecting and disconnecting the inductor to the battery such that the battery outputs a battery discharge pulse to the inductor, and the inductor transmitting a plurality of current pulses to the capacitor to build a charge of current on the capacitor, the controller intermittently connecting the capacitor to the load causing the capacitor to discharge the current pulse to the load, wherein the controller limits the pulses generated by the battery and the time between the pulses generated by the battery such that the resulting average electrical current draw from the battery is within the battery's optimal discharge rate.
7. A method for controlling the discharge of a battery to a load, said method comprising:
providing a switched inductor, said switched inductor having an inductor input switch with an input adapted to be connected to the battery, said switched inductor having a current output;
providing a capacitor adapted to be placed in circuit with the output of the inductor and collect the current output from the inductor;
providing a capacitor output switch in circuit with the capacitor, said capacitor output switch adapted to be connected to the load; and
providing a control module to control the operation of the inductor input switch and the capacitor output switch;
programming the control module to:
monitor the voltage on the capacitor;
periodically operate the inductor input switch to generate a plurality of current pulses from the battery to the capacitor;
allow the current pulses to generate a build-up of voltage on the capacitor to a predetermined voltage; and
operate the capacitor output switch to connect the capacitor to the load thereby discharging the voltage on the capacitor, wherein the control module limits the pulses generated by the battery and the time between the pulses generated by the battery such that the resulting average electrical current draw from the battery is within the battery's optimal discharge rate.