AC-to-DC voltage conversion and charging circuitry

• US 7,977,921 B2
• Filed: 08/15/2008
• Issued: 07/12/2011
• Est. Priority Date: 08/15/2008
• Status: Active Grant

• Current Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Original Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Liu, Qingguo, Bahai, Ahmad, Djabbari, Ali, Zhang, Jianhui
• Primary Examiner(s): Tso; Edward
• Assistant Examiner(s): WILLIAMS, ARUN C
• Application Number:
  US12/192,633
• Publication Number:
  US 20100039840A1
• Time in Patent Office: 1,061 Days
• Field of Search: 320/140, 320/166, 320/167
• US Class Current: 320/140
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices
• CPC Class Codes: H02M 1/0006 Arrangements for supplying an adequate voltage to the control circuit of converters
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 1/4208 Arrangements for improving power factor of AC input
• CPC Class Codes: H02M 3/1582 Buck-boost converters H02M3/1584 takes 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

Abstract

Voltage conversion and charging circuitry and method for converting an alternating current (AC) voltage to a direct current (DC) voltage for charging an energy storage element (e.g., battery or supercapacitor). An output capacitance, which is initially charged quickly for use in the slower charging of a battery, also maintains the charge on an input capacitance which provides power for the charging control circuitry during such charging process. In accordance with a preferred embodiment, the DC charging current is substantially constant during a first time interval following which the DC charging power is substantially constant during a second time interval.

Claims

1. An apparatus including voltage conversion and charging circuitry for converting an alternating current (AC) voltage to a direct current (DC) voltage for charging a battery, comprising:

first and second input electrodes to convey an AC voltage;

first and second output electrodes to convey a DC output voltage;

AC-to-DC voltage conversion circuitry coupled to said first and second input electrodes and responsive to said AC voltage by providing a first converted DC voltage;

a first capacitance coupled to said AC-to-DC voltage conversion circuitry and responsive to said first converted DC voltage by charging to a first charged DC voltage;

first DC-to-DC voltage conversion circuitry coupled to said first capacitance and responsive to said first charged DC voltage by providing a second converted DC voltage which is greater than said first charged DC voltage;

a second capacitance coupled to said first DC-to-DC voltage conversion circuitry and responsive to at least said second converted DC voltage by charging to a second charged DC voltage; and

second DC-to-DC voltage conversion circuitry coupled to said second capacitance and responsive to said second charged DC voltage by providing said DC output voltage which is less than said second charged DC voltage;

wherein, during an absence of said first converted DC voltage following said charging of said first capacitance to said first charged DC voltage, said first DC-to-DC voltage conversion circuitry is further responsive to said second charged DC voltage by substantially maintaining said first charged DC voltage on said first capacitance for at least a predetermined time interval.

2. The apparatus of claim 1, wherein:

said first DC-to-DC voltage conversion circuitry is responsive to said first charged DC voltage by providing a DC charging current;

said second charged DC voltage and said DC charging current together define a DC power;

said second capacitance is further responsive to said DC charging current by charging to said second charged DC voltage;

during a first time interval said DC charging current is substantially constant; and

during a second time interval following said first time interval said DC power is substantially constant.

3. The apparatus of claim 1, wherein:

said first and second input electrodes are further to convey an AC current;

said AC voltage and said AC current together define a power factor; and

said AC-to-DC voltage conversion circuitry comprises

power factor correction circuitry responsive to said AC voltage and one or more control signals by conducting said AC current in accordance with a predetermined power factor, and

control circuitry coupled to at least one of said first and second input electrodes and to said power factor correction circuitry, and responsive to said AC voltage and said AC current by providing said one or more control signals.

4. The apparatus of claim 3, wherein:

said AC voltage includes an associated signal phase;

said AC current includes an associated signal phase; and

said control circuitry comprises

comparison circuitry responsive to a comparison of said AC voltage signal phase and said AC current signal phase by providing a comparison result signal corresponding to said power factor, and

conversion circuitry coupled to said comparison circuitry and responsive to said comparison result signal by providing said one or more control signals.

5. The apparatus of claim 1, wherein said first DC-to-DC voltage conversion circuitry comprises bi-directional DC-to-DC voltage conversion circuitry.

6. The apparatus of claim 5, wherein said bi-directional DC-to-DC voltage conversion circuitry comprises bi-directional buck-boost DC-to-DC voltage conversion circuitry.

7. The apparatus of claim 1, wherein:

a first DC current is conveyed between said first capacitance and said first DC-to-DC voltage conversion circuitry;

a second DC current is conveyed between said first DC-to-DC voltage conversion circuitry and said second capacitance;

said first DC-to-DC voltage conversion circuitry is further responsive to said first and second charged DC voltages and one or more control signals by conveying said first and second DC currents; and

said apparatus further comprises control circuitry coupled to said first and second capacitances and said first DC-to-DC voltage conversion circuitry, and responsive to said first and second charged DC voltages and said first and second DC currents by providing said one or more control signals.

8. The apparatus of claim 7, wherein said control circuitry comprises:

first comparison circuitry responsive to a comparison of said second DC current to a reference current by providing a current comparison signal;

multiplication circuitry responsive to said second charged DC voltage and said second DC current by providing a power signal;

second comparison circuitry coupled to said multiplication circuitry and responsive to a comparison of said power signal to a reference power by providing a power comparison signal; and

one or more controllers coupled to said first and second comparison circuitries and responsive to said current and power comparison signals by providing said one or more control signals.

9. The apparatus of claim 8, wherein at least one of said one or more controllers comprises a proportional, integral, derivative (PID) controller.

10. The apparatus of claim 8, wherein said one or more control signals comprises a plurality of control signals, and said one or more controllers comprises:

a first controller coupled to said first comparison circuitry and responsive to said current comparison signal by providing a first one of said plurality of control signals; and

a second controller coupled to said second comparison circuitry and responsive to said power comparison signal by providing a second one of said plurality of control signals.

11. The apparatus of claim 10, wherein said first and second controllers comprise first and second proportional, integral, derivative (PID) controllers, respectively.

12. The apparatus of claim 1, wherein:

said first and second output electrodes are further to convey a DC output current;

said second DC-to-DC voltage conversion circuitry is further responsive to said second charged DC voltage and one or more control signals by providing said DC output current; and

said apparatus further comprises control circuitry coupled to said first capacitance, at least one of said first and second output electrodes, and said second DC-to-DC voltage conversion circuitry, and responsive to said first charged DC voltage, said DC output voltage and said DC output current by providing said one or more control signals.

13. The apparatus of claim 12, wherein said second DC-to-DC voltage conversion circuitry comprises DC-to-DC voltage buck conversion circuitry.

14. The apparatus of claim 12, wherein said control circuitry comprises:

first comparison circuitry responsive to a comparison of said DC output current to a reference current by providing a current comparison signal;

multiplication circuitry responsive to said DC output voltage and said DC output current by providing a power signal;

second comparison circuitry responsive to a comparison of said power signal to a reference power by providing a power comparison signal; and

one or more controllers coupled to said first and second comparison circuitries and responsive to said current and power comparison signals by providing said one or more control signals.

15. The apparatus of claim 14, wherein at least one of said one or more controllers comprises a proportional, integral, derivative (PID) controller.

16. The apparatus of claim 14, wherein said one or more control signals comprises a plurality of control signals, and said one or more controllers comprises:

a first controller coupled to said first comparison circuitry and responsive to said current comparison signal by providing a first one of said plurality of control signals; and

a second controller coupled to said second comparison circuitry and responsive to said power comparison signal by providing a second one of said plurality of control signals.

17. The apparatus of claim 16, wherein said first and second controllers comprise first and second proportional, integral, derivative (PID) controllers, respectively.

18. An apparatus including voltage conversion and charging circuitry for converting an alternating current (AC) voltage to a direct current (DC) voltage for charging a battery, comprising:

AC-to-DC voltage converter means for receiving and converting an AC voltage to a first converted DC voltage;

first capacitor means for receiving said first converted DC voltage and in response thereto charging to a first charged DC voltage;

first DC-to-DC voltage converter means for receiving and converting said first charged DC voltage to a second converted DC voltage which is greater than said first charged DC voltage;

second capacitor means for receiving at least said second converted DC voltage and in response thereto charging to a second charged DC voltage; and

second DC-to-DC voltage converter means for receiving and converting said second charged DC voltage to a DC output voltage which is less than said second charged DC voltage;

wherein, during an absence of said first converted DC voltage following said charging of said first capacitance to said first charged DC voltage, said first DC-to-DC voltage converter means is further for receiving said second charged DC voltage and in response thereto substantially maintaining said first charged DC voltage on said first capacitor means for at least a predetermined time interval.

19. A method for converting an alternating current (AC) voltage to a direct current (DC) voltage for charging a battery, comprising:

converting an AC voltage to a first converted DC voltage;

receiving said first converted DC voltage and in response thereto charging a first capacitance to a first charged DC voltage;

converting said first charged DC voltage to a second converted DC voltage which is greater than said first charged DC voltage;

receiving at least said second converted DC voltage and in response thereto charging a second capacitance to a second charged DC voltage;

converting said second charged DC voltage to a DC output voltage which is less than said second charged DC voltage; and

during an absence of said first converted DC voltage following said charging of said first capacitance to said first charged DC voltage, receiving said second charged DC voltage and in response thereto substantially maintaining said first charged DC voltage on said first capacitance for at least a predetermined time interval.