Switch mode battery charger with improved battery charging time

• US 9,559,538 B1
• Filed: 06/24/2013
• Issued: 01/31/2017
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Maxim Integrated Products, Inc. (Analog Devices, Inc.)
• Original Assignee: Maxim Integrated Products, Inc. (Analog Devices, Inc.)
• Inventors: Bonte, Olivier, Belch, Mark
• Primary Examiner(s): Dunn, Drew A
• Assistant Examiner(s): Zhou, Zixuan
• Application Number:
  US13/925,700
• Time in Patent Office: 1,317 Days
• Field of Search: 320/115, 320/134, 320/136, 320/137
• US Class Current: 1/1
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 2207/40 adapted for charging from various sources, e.g. AC, DC or multivoltage
• CPC Class Codes: H02J 50/001 Energy harvesting or scavenging
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/007 Regulation of charging or discharging current or voltage
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage

Abstract

Various embodiments of the invention relate to a battery charging system that enhances the charge rate and reduces the charge time for a battery applied in a mobile device. The battery charging system is provided with an adapter output voltage, and generates a battery charging current to drive the battery. This adapter output voltage is controlled to vary within a reference voltage range which is narrowly controlled to include and track a preferred adapter voltage. The battery is therefore driven by the battery charging current that is associated with a preferred charging current under a preferred charging condition. The battery charging process may be completed under a condition that is substantially close to the preferred charging condition, allowing an enhanced battery charge rate and a reduced battery charge time.

Claims

1. A battery charging system for a mobile device, comprising:

an adapter that receives power from a power source and generates an adapter output voltage, the adapter output voltage being outputted to vary within a reference voltage range that is substantially narrow and includes a preferred adapter voltage, the preferred adapter voltage being associated with a preferred battery charging condition under which the battery is driven and charged up with a preferred charging power;

a battery charger, coupled to the adapter, the battery charger generating a battery charging current that is monitored to allow the reference voltage range to track a variation of load condition at the output of the adapter; and

a battery, coupled to the battery charger, the battery being driven and charged up by the battery charging current when the mobile device is coupled to the power source, power stored in the battery being further used to drive normal operation of the mobile device when the mobile device is decoupled from the power source;

wherein the preferred battery charging condition is determined when a variation of the battery charging current is sensed to drop during a course of gradually reducing the adapter output voltage from an initial voltage based on a constant voltage step.

2. The battery charging system according to claim 1, wherein the power source is the conventional main electricity, and the adapter is an AC-DC voltage regulator that converts an AC supply voltage to a DC supply voltage, i.e., the adapter output voltage.

3. The battery charging system according to claim 1, wherein the battery charger is implemented as a switching mode battery charger that includes alternative active and inactive periods and further comprises:

a switching regulator that generates at least one converter control; and

a buck converter, coupled to the switching regulator, the buck converter comprising at least one inductor for temporary energy storage and being controlled by the at least one converter control to convert the adapter output voltage to the battery charging current.

4. The battery charging system according to claim 3, wherein the switching regulator monitors the output condition of the adapter and adjusts the reference voltage range.

5. The battery charging system according to claim 1, wherein the reference voltage range comprises the voltage step when the preferred battery charging condition is determined and two additional voltage steps that are precedent to the voltage step.

6. A battery charging system that charges up a battery for a mobile device, comprising:

an adapter that receives power from a power source and generates an adapter output voltage, the adapter output voltage being outputted to vary within a reference voltage range, the reference voltage range being substantially narrow and tracking a variation of load condition at the output of the adapter to include a preferred adapter voltage;

a battery charger, coupled to the adapter, the battery charger generating a battery charging current to drive and charge up the battery when the mobile device is coupled to the power source, power stored in the battery being further used to drive normal operation of the mobile device when the mobile device is decoupled from the power source; and

wherein under a preferred battery charging condition, the battery is driven with a preferred charging power that is associated with the preferred adapter voltage in order to achieve a quick battery charge, and

wherein the preferred battery charging condition is determined when a variation of the battery charging current is sensed to drop during a course of gradually reducing the adapter output voltage from an initial voltage based on a constant voltage step.

7. The battery charging system according to claim 6, wherein the battery charging current is monitored to determine the preferred battery charging condition that changes with the variation of load condition at the output of the adapter, allowing the reference voltage range to track the variation accordingly.

8. The battery charging system according to claim 6, wherein the adapter is a standalone device, while the battery charger is integrated in the mobile device.

9. The battery charging system according to claim 6, wherein the power source provides one form of energy selected from electromagnetic, solar, kinetic and thermal energy, and an interface is included in the adapter to harvest energy based on the selected form of energy.

10. The battery charging system according to claim 6, wherein the battery charger is implemented as a switching mode battery charger that includes alternative active and inactive periods and further comprises:

a switching regulator that generates at least one converter control; and

a buck converter, coupled to the switching regulator, the buck converter comprising at least one inductor for temporary energy storage and being controlled by the at least one converter control to convert the adapter output voltage to the battery charging current.

11. The battery charging system according to claim 10, wherein the switching regulator monitors the output condition of the adapter and adjusts the reference voltage range.

12. The battery charging system according to claim 6, wherein the reference voltage range comprises the voltage step when the preferred battery charging condition is determined and two additional voltage steps that are precedent to the voltage step.

13. A method of efficiently charging a battery in a mobile device, comprising the steps of:

determining a reference voltage range that includes a preferred adapter voltage, the preferred adapter voltage being associated with a preferred battery charging condition under which an adapter receives power from a power source to drive and charges up the battery with a preferred charging power, the reference voltage range being substantially narrow and tracking a variation of load condition at the output of the adapter;

generating an adapter output voltage within the reference voltage range, the adapter output voltage varying within the reference voltage range; and

generating a battery charging current to drive and charge up the battery when the mobile device is coupled to the power source;

power stored in the battery being further used to drive normal operation of the mobile device when the mobile device is decoupled from the power source;

wherein the preferred battery charging condition is determined when a variation of the battery charging current is sensed to drop during a course of gradually reducing the adapter output voltage from an initial voltage by a constant voltage step.

14. The method according to claim 13, wherein the battery charging current is monitored to determine the preferred battery charging condition that changes with the variation of load condition at the output of the adapter, allowing the reference voltage range to track the variation accordingly.

15. The method according to 13, wherein the power source is the conventional main electricity, and the adapter is an AC-DC voltage regulator that converts an AC supply voltage to a DC supply voltage, i.e., the adapter output voltage.

16. The method according to 13, wherein the power source provides one form of energy selected from electromagnetic, solar, kinetic and thermal energy, and an interface is included in the adapter to harvest energy from the selected form of energy.

17. The method according to 13, wherein the reference voltage range comprises the voltage step when the preferred battery charging condition is determined and two additional voltage steps that are precedent to the voltage step.