Dynamically-switched power converter

• US 6,646,415 B1
• Filed: 04/12/2002
• Issued: 11/11/2003
• Est. Priority Date: 06/25/1999
• Status: Expired due to Fees

• Current Assignee: Board of Trustees of The University of Illinois
• Original Assignee: Board of Trustees of The University of Illinois
• Inventors: Gartstein, Vladimir, Nebrigic, Dragan Danilo
• Primary Examiner(s): TIBBITS, PIA FLORENCE
• Application Number:
  US10/009,872
• Time in Patent Office: 578 Days
• Field of Search: 320/104, 320/107, 320/108, 320/148, 320/157, 320/166, 320/167, 363/49, 363/59, 363/60
• US Class Current: 320/107
• CPC Class Codes: H01M 10/488 Cells or batteries combined with indicating means for external visualization of the condition, e.g. by change of colour or of light density
• CPC Class Codes: H01M 6/5044 Cells or batteries structurally combined with cell condition indicating means
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02M 3/07 using capacitors charged and discharged alternately by semiconductor devices with control electrode , e.g. charge pumps
• CPC Class Codes: H02M 3/1588 comprising at least one synchronous rectifier element H02M3/1582, H02M3/1584 take precedence
• CPC Class Codes: Y02B 40/00 Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A DC/DC power converter is efficiently switched to produce a predetermined output voltage across a load capacitor as required by a load device. In particular, a capacitive and/or inductive element is switched between a charge and discharge state as required to maintain the output voltage. For a capacitive-only power converter, or charge pump, comparison of the output voltage to a reference voltage efficiently switches a fly capacitor between charging and discharging states. Also, power converter based on switching of an inductive element with a synchronous rectifier and switch to charge the load capacitor is made more efficient by a hysteretic comparison of the output voltage to predetermined thresholds for stopping the Pulse Width Modulation (PWM) modulation when the predetermined output voltage is achieved. The power converters illustrated are suitable for integrated circuit implementation and may be combined with other elements of a battery to produce a more efficient battery, achieving longer service life and output voltage stability.

Claims

1. A battery comprising:

a voltaic cell including a positive electrode and a negative electrode, the cell storing electrical charge resulting in an electrode voltage across the positive and negative electrodes;

a container substantially encompassing the voltaic cell, the container including a positive terminal and a negative terminal; and

characterized in that

a dynamically-switched capacitive charge pump electrically interposed between the electrodes and the terminals, the charge pump substantially encompassed by the container, preferably wherein the dynamically-switched capacitive charge pump includes an integrated circuit.

2. The battery of claim 1 wherein the capacitive charge pump includes an output capacitor electrically coupled across the positive and negative terminals and wherein the capacitive charge pump includes a fly capacitor alternately electrically coupled across the electrodes to charge in a charge mode and in additive series combination with the voltaic cell to discharge into the output capacitor in a discharge mode, preferably wherein one of the fly capacitor and the output capacitor is a high efficiency capacitor.

3. The battery of any of the preceding claims wherein the charge pump further includes:

a switching matrix electrically switchably coupling the fly capacitor, the output capacitor, and the voltaic cell between the charge mode and the discharge mode; and

a switching matrix controller operatively coupled to the switching matrix to command the switching between charge and discharge modes, preferably wherein the switching matrix controller includes a comparator responsive to the output voltage falling below a predetermined threshold to command the switching matrix to the discharge mode and responsive to the output voltage rising above the predetermined threshold to command the switching matrix to the charge mode, even more preferably wherein the comparator includes a hysteresis circuit to prevent rapid oscillation when the output voltage approaches the predetermined threshold and/or the comparator includes an output stage including an amplifier and hysteresis device.

4. The battery of any of the preceding claims further including one or more of the following:

(a) an internal power supply electrically coupled to the voltaic cell as a voltage source, the internal power supply electrically biasing the switching matrix controller; and

(b) a voltage reference circuit providing a voltage reference to the switching matrix controller, preferably including a temperature compensation circuit for the voltage reference circuit.

5. The battery of any of the preceding claims wherein the switching matrix comprises a first switch electrically switchably coupling the positive electrode to a first end of the fly capacitor, a second switch electrically switchably coupling the first end of the fly capacitor to the positive terminal of the battery, a third switch electrically switchably coupling the negative electrode to a second end of the fly capacitor, and a fourth switch electrically switchably coupling the second end of the fly capacitor to the positive electrode, preferably wherein the first switch, second switch, third switch, and fourth switch are comprised respectively of integrated circuit field effect, and wherein the first and third switches are closed with the second and fourth switches open to affect the charge mode and inversely for the discharge mode, even more preferably wherein the switching matrix further includes an initial condition wherein a portion of the power converter is deactivated.

6. The battery of any of the preceding claims wherein the voltaic cell comprises a selected one of a lithium electrochemical cell and an alkaline electrochemical cell.

7. A power management circuit configured to adjust an output voltage across positive and negative terminals of a battery, the battery further including a voltaic cell having a positive electrode and a negative electrode, a fly capacitor, and a load capacitor electrically coupled across the terminals, the power management circuit comprising:

a switching matrix being electrically switchable between a charge mode and a discharge mode, wherein the switching matrix in charge mode comprises being configured to electrically couple the fly capacitor across the electrodes of the voltaic cell, and wherein the switching matrix in discharge mode comprises being configured to electrically couple across the load capacitor the series combination of the voltaic cell and the fly capacitor; and

a switching matrix controller operatively coupled to the switching matrix to select the charge and discharge modes.

8. The power management circuit of claim 7 wherein the switching matrix comprises one of the following:

a noninverting switched capacitive device, an inverting switched capacitive device and an inductive power converter.

9. A power converter with input terminals for coupling to an energy source and output terminals for coupling to a load device, the power converter comprising:

an output stage for selectively coupling the input terminals to the output terminals to deliver energy from an energy source to a load device;

a start-stop controller operably coupled to the output stage for pulse width modulation controlling said selective coupling of the input and output terminals;

the output stage comprising an inductive element coupled to the input terminals, a capacitive element coupled to the output terminals, a rectifying element closingly responsive to a first state and openly responsive to a second state, and a switch responsive to a control signal S2 from the controller, the rectifying element and the switch being operably coupled with respect to said inductive and capacitive elements for causing the inductive element to be coupled to the capacitive element to discharge energy therefrom into the capacitive element during the first state and causing the inductive element to be energized during the second state;

the start-stop controller being hysteretically responsive to input signals from the output stage indicating a charged capacitive element for discontinuing coupling of the input and output terminals.