Efficient power transfer system

• US 5,396,165 A
• Filed: 02/02/1993
• Issued: 03/07/1995
• Est. Priority Date: 02/02/1993
• Status: Expired due to Fees

• Current Assignee: Microchip Technology Incorporated
• Original Assignee: Teledyne Industries Incorporated (Teledyne Technologies Incorporated)
• Inventors: Yu, Wen H., Chen, George C., Lin, Gary J., Reischl, Peter, Bhatt, Kartik, Hwang, Jeffrey H.
• Primary Examiner(s): Sterrett, Jeffrey L.
• Application Number:
  US08/013,809
• Time in Patent Office: 763 Days
• Field of Search: 323/205, 323/207, 323/210, 323/222, 323/266, 323/267, 323/282, 323/299, 363/39, 363/44, 363/62, 363/84, 363/89, 363/125, 363/126
• US Class Current: 323/210
• CPC Class Codes: G05F 1/70 Regulating power factor; Regulating reactive current or power
• CPC Class Codes: H02J 7/00308 Overvoltage protection
• CPC Class Codes: H02J 7/0047 with monitoring or indicating devices or circuits
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters
• CPC Class Codes: H02M 3/005 using Cuk converters

Abstract

A power transfer method and apparatus for efficient transfer of power are disclosed. Input power is converted in an essentially lossless manner to an intermediate form having a voltage or current in excess of that desired at the load. The intermediate power form is split into first and second parts, where the first part of the intermediate power form approximately matches an output power form desired at an output of the power transfer apparatus and the second part represents an excess power form. The first part of the intermediate power form is transferred to the output of the power transfer apparatus and the excess part is stored. Part or all of the stored excess energy is recycled in an essentially lossless manner, converted into a form that approximately matches the output power form desired at the output of the power transfer apparatus and transferred to the output of the power transfer apparatus.

Claims

1. A power transfer system for transferring power from a power source having predefined voltage parameters or predefined current parameters to a load across which it is desirable to develop a predefined load voltage or through which it is desirable to develop a predefined load current, said power transfer system comprising:

input power-form converting means for receiving input power from the power source and for converting the received input power into an intermediate power form having an intermediate voltage and an intermediate current, where at least one of the intermediate voltage and the intermediate current exceeds a corresponding one of the predefined load voltage and predefined load current that are to be desirably produced at the load;

intermediate power-form splitting means, coupled to the input power-form converting means, for splitting at least one of the intermediate voltage and the intermediate current in an essentially lossless manner into a first split part and a second split part, where the first split part substantially matches at least a corresponding one of the predefined load voltage and predefined load current that are to be desirably produced at the load and the second split part represents excess energy;

transfer means, coupled to the intermediate power-form splitting means, for transferring the first split part to the load; and

excess power storage means, coupled to the input power-form converting means, for storing the excess-representing second split part.

2. The power transfer system of claim 1 further comprising:

excess energy recycling means, coupled to the excess power storage means, for converting part or all of the second split part into a recycled power form and for directing the recycled power form to the load.

3. The power transfer system of claim 2 wherein the excess-representing, second split part includes an excess voltage and the excess energy recycling means includes:

voltage-to-current converting means for converting part or all of the excess voltage into an excess-representing current; and

current directing means, coupled to the voltage-to-current converting means, for directing the excess-representing current to the load.

4. The power transfer system of claim 1 wherein the power source includes an AC power source that supplies an alternating current form of power having a power factor and the input power-form converting means includes:

rectifier means, coupled to the AC power source, for converting the alternating current form to a unipolar power form;

intermediate current range defining means, coupled to the rectifier means, for drawing a first current from the rectifier means and for defining a steady-state range of magnitudes for the drawn first current, where the drawn first current determines the magnitude of AC current drawn from the AC power source; and

power-factor correcting means, responsive to the voltage and current of the AC power source and operatively coupled to control the intermediate current range defining means, for urging the current portion of the unipolar power form to have a magnitude or envelope that substantially tracks the voltage portion of the unipolar power form.

5. The power transfer system of claim 1 further comprising:

isolation means, interposed between the power source and the load, for providing DC or low frequency isolation between the power source and the load.

6. The power transfer system of claim 5 wherein the isolation means includes one or more DC blocking capacitors interposed between the power source and the load.

7. The power transfer system of claim 5 wherein the isolation means includes an isolation transformer interposed between the power source and the load for providing DC isolation between the power source and the load.

8. A power transfer system for transferring power from a power source having predefined voltage parameters or predefined current parameters to a load across which it is desirable to develop a predefined load voltage or through which it is desirable to develop a predefined load current, said power transfer system comprising:

power input means for receiving input power of a form having a unipolar input voltage and a unidirectional input current;

first current switching means, coupled to the power input means, for selectively directing the unidirectional input current into a first current loop that carries a first current or into a second current loop that carries a second current;

first power-form converting means, coupled to the first current switching means, for receiving the second current of the second current loop, for converting the second current into an intermediate voltage in an essentially lossless manner, and for splitting the intermediate voltage in an essentially lossless manner into a first part voltage and a second part voltage; and

second power-form converting means, coupled to the first power-form converting means, for converting part or all of the second part voltage into a power recycling current and for directing the power recycling current to the load.

9. The power transfer system of claim 8 wherein said first power-form converting means includes first storage means for storing the second part voltage.

10. The power transfer system of claim 8 wherein said first power-form convercing means includes second storage means for storing the first part voltage.

11. A power transfer system for transferring power to a load having a load voltage thereacross, said power transfer system comprising:

power input means for receiving input power of a form having a unipolar voltage;

voltage converting means for converting the input unipolar voltage into an intermediate voltage in an essentially lossless manner, where the intermediate voltage is greater than the load voltage; and

voltage splitting and storing means for splitting the intermediate voltage in an essentially lossless manner into a first part voltage matching the load voltage and a second part voltage representing a difference between the intermediate voltage and the load voltage, and for storing the second part voltage.

12. A power transfer system according to claim 11 further comprising:

excess power recycling means for converting part or all of the stored second part voltage into a power recycling current and for directing the power recycling current to the load.

13. A power transfer system according to claim 12 wherein the load includes self-regulating means for maintaining the load voltage at a predefined level.

14. A power transfer system according to claim 13 wherein the self-regulating means includes a battery.

15. A power transfer system according to claim 14 wherein the battery of the self-regulating means is a chargeable battery.

16. A power transfer system comprising:

a set of first through sixth circuit nodes, where the second and first nodes are adapted to receive a unipolar input voltage thereacross and the sixth and first nodes are adapted to output a load current to a load;

a first inductor having ends coupled respectively to the second and third nodes;

a first capacitor having ends coupled respectively to the third and fourth nodes;

a second inductor;

a controllable switch having ends coupled respectively to the first and third nodes;

a first unidirectional current directing means coupled to the first capacitor for directing current from the first capacitor by way of the fourth node unidirectionally into the sixth node;

a second unidirectional current directing means coupled in series with said second inductor, the series combination formed by the second inductor and the second unidirectional current directing means including said fifth node, said series combination being coupled between the first and fourth nodes for directing current unidirectionally from the first node through the second inductor to the fourth node; and

a switch control unit operatively coupled to the controllable switch for alternatingly opening and closing the controllable switch.

17. A power transfer system according to claim 16 wherein:

the second inductor has a first end connected to the fourth node and a second end connected to the fifth node; and

the second unidirectional current directing means has a first end connected to the fifth node and a second end connected to the first node.

18. A power transfer system according to claim 16 further comprising charge storage means connected to the first and sixth nodes for storing charge.

19. A power transfer system according to claim 18 wherein said charge storage means includes a chargeable battery.

20. A power transfer system according to claim 16 wherein said unipolar input voltage is pulsed.

21. A power transfer method for transferring power from a power source having given voltage parameters or given current parameters to an output port across which it is desirable to develop a predefined output voltage or through which it is desirable to develop a predefined output current, said power transfer method comprising the steps of:

developing or obtaining an intermediate power form having an intermediate voltage and an intermediate current, where at least one of the intermediate voltage and the intermediate current exceeds a corresponding one of the predefined output voltage and predefined output current that are to be desirably produced at the output port;

splitting at least one of the intermediate voltage and the intermediate current in an essentially lossless manner into a first split part and a second split part, where the first split part substantially matches at least a corresponding one of the predefined load voltage and predefined 10ad current that are to be desirably produced at the output port and the second split part represents excess energy;

transferring the first split part to the output port; and

storing the excess-representing second split part.

22. A power transfer method according to claim 21 further comprising the step of limiting the magnitude of at least one of the intermediate voltage and the intermediate current to a predefined maximum value.

23. An interconnected plurality of power transfer systems where each power transfer system comprises:

input current receiving means for receiving input current surges representing surges of input power;

form converting and splitting means, operatively coupled to the input current receiving means, for converting the received input current surges into a split voltage, the split voltage having a first part representing excess power and a second part representing a portion of one or more of the received surges of input power that is to be output from the power transfer system, where the form converting and splitting means includes excess power storage means for storing the first part of the split voltage; and

power output means, operatively coupled to the form converting and splitting means, for outputting power derived from said second part of the split voltage out of the power transfer system.

24. An interconnected plurality of power transfer systems according to claim 23 where the power output means of a first of said plurality of power transfer systems is operatively coupled to the input current receiving means of a second of said plurality of power transfer systems for transferring power from the first power transfer system to the second power transfer system.

25. An interconnected plurality of power transfer systems according to claim 23 where the power output means of a first of said plurality of power transfer systems is operatively coupled to the power output means of a second of said plurality of power transfer systems for merging the power output of the first power transfer system with the power output of the second power transfer system.

26. An interconnected plurality of power transfer systems according to claim 23 where the input current receiving means of a first of said plurality of power transfer systems operatively coupled to the input current receiving means of a second of said plurality of power transfer systems for splitting input power between the first power transfer system and the second power transfer system.

27. An interconnected plurality of power transfer systems according to claim 26 further comprising:

a shared current surge generating means, operatively coupled to the input current receiving means of the first and second power transfer systems, for supplying said input current surges either in parallel or multiplexed over time to the first and second power transfer systems.

28. An interconnected plurality of power transfer systems according to claim 27 where the shared current surge generating means comprises:

a shared inductor; and

a shared switching means for alternatingly applying a unipolar voltage across the shared inductor to develop a magnetic field-replenishing current in the shared inductor and for directing field-depleting surges of current from the shared inductor to the first and second power transfer systems.

29. An interconnected plurality of power transfer systems according to claim 23 further comprising:

current distributing means, operatively coupled to the input current receiving means of at least a first of said plurality of power transfer systems and of at least second of said plurality of power transfer systems, for splitting input power on a time-multiplexed basis between the first power transfer system and the second power transfer system.

30. A multi-input power transfer system for transferring power to a load from a plurality of unipolar voltage sources, the multi-input power transfer system comprising:

input current receiving means for receiving input current surges representing surges of input power;

form converting and splitting means, operatively coupled to the input current receiving means, for converting the received input current surges into a split voltage, the split voltage having a first part representing excess power and a second part representing a portion of one or more of the received surges of input power that is to be output from the power transfer system, where the form converting and splitting means includes excess power storage means for storing the first part of the split voltage;

power output means, operatively coupled to the form converting and splitting means, for outputting power derived from said second part of the split voltage out of the power transfer system; and

a current surge generating means, operatively coupled to receive power from the plurality of unipolar voltage sources and operatively coupled to the input current receiving means, for converting the voltage of at least one of said unipolar voltage sources into the input current surges and for supplying said input current surges to the input current receiving means.

31. A multi-input power transfer system according to claim 30 wherein the current surge generating means comprises:

a plurality of inductors each coupled to receive power from a corresponding one of said plurality of unipolar voltage sources;

a plurality of current directing means, operatively coupled to respective ones of the inductors, for directing current flow from the respective inductors to the input current receiving means; and

switching means, operatively coupled to the plurality of inductors, for alternatingly applying a unipolar voltage of at least one of said unipolar voltage sources across a respective one of said inductors to develop a magnetic field-replenishing current in the respective one inductor and for directing field-depleting surges of current from the respective one inductor to the input current receiving means.

32. A cyclical power transfer system for transferring power over successive cycles from a power source to a load, the cyclical power transfer system comprising:

power receiving means for receiving in alternating ones of the cycles first quantums of charge per cycle from the power source, where one or more of the first quantums of charge per cycle exceeds a second quantum of charge per cycle that is to be absorbed by the load;

charge splitting and storing means, operatively coupled to the power source, for subdividing the quantum of charge supplied by the power source during each of said alternating ones of the cycles in an essentially lossless manner into first and second parts, where the first part of the subdivided source quantum of charge approximately matches the second quantum of charge that is to be absorbed by the load and the second part of the subdivided source quantum of charge represents excess charge on a per cycle basis, and for storing the excess-representing second part of the subdivided source quantum of charge; and

excess charge recycling means, operatively coupled to the charge splitting and storing means, for recycling part or all of the stored excess charge in an essentially lossless manner in other ones of said cycles to the load, said recycling including converting the recycled excess charge into a form that approximately matches a power form desired at the load.

33. A current drawing method for drawing current from a unipolar power source having a given voltage waveform and causing the drawn current to have a waveform which has a prescribed relation to the waveform of the given voltage;

said method being for supplying power to a load at which it is desirable to develop a load voltage or load current different from the that of the unipolar power source, said method comprising the steps of;

alternatingly applying the given voltage across a first inductor so as to establish a first current flowing through the first inductor and removing a second current from the first inductor such that the magnitude of the drawn current is alternatingly defined by the values for the first and second currents; and

controlling the timings of said alternating application of the given voltage and removal of the second current independently of the establishment at the load of said load voltage or load current so as to establish a range of minimum and maximum values for the first and second currents thereby causing the drawn current to have a waveform which has a prescribed relation to the waveform of the given voltage.

35. A current drawing method according to claim 33 wherein said unipolar power source is driven by an alternating current power source and the step of controlling the timings of said alternating application of the given voltage and removal of the second current maintains at least a prescribed minimum power factor for the power delivered from the alternating current power source to the unipolar power source.

34. A current drawing method for drawing current from a unipolar power source having a given voltage waveform and for causing the drawn current to have a waveform which has a prescribed relation to the waveform of the given voltage, said method comprising the steps of:

alternatingly applying the given voltage across a first inductor so as to establish a first current flowing through the first inductor and removing a second current from the first inductor such that the magnitude of the drawn current is alternatingly defined by the values for the first and second currents; and

controlling the timings of said alternating application of the given voltage and removal of the second current so as to establish a range of minimum and maximum values for the first and second currents thereby causing the drawn current to have a waveform which has a prescribed relation to the waveform of the given voltage;

wherein said step of controlling the timings of said alternating application of the given voltage and removal of the second current produces an intermediate voltage and an intermediate current;

wherein at least one of the intermediate voltage and the intermediate current exceeds a corresponding one of a predefined output voltage and predefined output current that are to be desirably produced at an output port; and

wherein said method further comprises the steps of;

splitting at least one of the intermediate voltage and the intermediate current in an essentially lossless manner into a first split part and a second split part, where the first split part substantially matches at least a corresponding one of the predefined load voltage and predefined load current that are to be desirably produced at the output port and the second split part represents excess energy; and

storing the excess-representing second split part.

36. A power factor correcting and power transfer system for transferring power from a power source having a source voltage and a source current, wherein one of the source voltage and source current has a predefined magnitude versus time waveform, to a load at which it is desirable to develop a different load voltage or load current, where an over-time relationship between the source voltage and source current defines a source power factor and an amount of power drawn per unit of time from the power source, said power factor correcting and power transfer system comprising:

current drawing means, operatively coupled to the power source, for drawing first and second currents from the power source, where the first and second currents flow alternatingly in successive and respective time periods, the first current increases in magnitude during its respective time periods, the second current decreases in magnitude over its corresponding time periods, and the magnitude of the first current at the end of its respective time periods defines the magnitude of the second current at the beginning of its corresponding time periods;

control means, operatively coupled to the current drawing means, for controlling the magnitudes of the first and second currents drawn from the power source such that an envelope defined by at least peak values of the first and second currents substantially tracks the source voltage oven time; and

power transfer means, operatively coupled to the current drawing means, for transferring part or essentially all of the power drawn per unit of time from the power source to the load, said power transfer means including output parameter defining means for defining independently of the control means the different load voltage or load current.

37. A power factor correcting and power transfer system according to claim 36 wherein the envelope that substantially tracks the source voltage is defined by peak and minimum values of the first and second currents.

38. A power factor correcting and power transfer system according to claim 36 wherein minimum values of the first and second currents are at or substantially close to zero.

39. A power factor correcting and power transfer system according to claim 36 wherein the output parameter defining means includes:

excess power storage means, operatively coupled to the current drawing means, for storing excess power defined by a difference between the power drawn per unit of time from the power source and power absorbed per unit of time by the load.

40. A power factor correcting and power transfer system according to claim 39 further comprising:

excess power recycling means, operatively coupled to the excess power storage means and the load, for transferring pre-stored excess power to the load.

41. A power factor correcting and power transfer system according to claim 36 wherein an envelope defined by minimum values of the first and second currents does not substantially track the source voltage over time.