CONTACTLESS INDUCTIVELY COUPLED POWER TRANSFER SYSTEM

• US 20140092649A1
• Filed: 09/17/2013
• Published: 04/03/2014
• Est. Priority Date: 09/28/2012
• Status: Active Grant

• Current Assignee: PowerWoW Technology Inc.
• Original Assignee: PowerWoW Technology Inc.
• Inventors: Hsu, Jr-Uei
• Granted Patent: US 9,755,536 B2
• Time in Patent Office: Days
• US Class Current: 363/34
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/40 using two or more transmitting or receiving devices H02J50/50 takes precedence
• CPC Class Codes: H02M 5/42 by static converters

Abstract

A contactless inductively coupled power transfer system includes a power supply device and a power receiving device. The power supply device includes a primary winding for generating an electromagnetic field (EMF) in response to an AC current flow having an operating frequency. The power receiving device includes a resonant circuit outputting an output voltage to a load and including a secondary winding and a reactance element. The reactance element is capable of forming a parallel resonant LC circuit with the secondary winding that resonates at the operating frequency, and forming a series resonant LC circuit that resonates at the operating frequency, and that is to be connected in series to the load.

Claims

1. A contactless inductively coupled power transfer (ICPT) system comprising:

a power supply device including a primary winding which is for generating an electromagnetic field in response to an alternating current (AC) current flow having a variable operating frequency; and

a power receiving device including a resonant circuit which is adapted to output an output voltage to a load according to induction of the electromagnetic field, and which includes

a secondary winding that generates an open-circuit voltage according to induction of the electromagnetic field, the output voltage being associated with the open-circuit voltage, and

a reactance element coupled electrically to said secondary winding and capable of forming a parallel resonant LC circuit with the secondary winding, the parallel resonant LC circuit resonating at the operating frequency, said reactance element being configured to form a series resonant LC circuit that resonates at the operating frequency, and that is to be connected in series to the load.

2. The contactless ICPT system as claimed in claim 1, wherein said power receiving device includes:

a first control circuit coupled electrically to said resonant circuit, to be coupled electrically to the load, and including

a first controller which detects the output voltage of said resonant circuit, which receives a reference voltage representing the open-circuit voltage, and which calculates and outputs a first control signal based on the reference voltage and the output voltage for controlling said resonant circuit to maintain resonance, and

a second controller which is for detecting a load voltage across the load, which stores a preset voltage, and which calculates and outputs a second control signal based on the load voltage and the preset voltage for controlling said resonant circuit such that the load voltage is substantially equal to the preset voltage.

3. The contactless ICPT system as claimed in claim 2, wherein said first controller controls capacitances of the parallel resonant LC circuit and the series resonant LC circuit, and said second controller controls inductance of the series resonant LC circuit.

4. The contactless ICPT system as claimed in claim 2, wherein said first controller controls inductance of the series resonant LC circuit, and said second controller controls capacitances of the parallel resonant LC circuit and the series resonant LC circuit.

5. The contactless ICPT system as claimed in claim 2, wherein said first control circuit further includes a reference voltage generator, capacitance and inductance of the series resonant LC circuit being set to enable an initial state of the output voltage to turn on said first control circuit such that said reference voltage generator is activated, said reference voltage generator being configured to:

adjust one of the capacitance and the inductance of the series resonant LC circuit so as to vary the output voltage of said resonant circuit;

receive the output voltage when the output voltage reaches a peak value, the output voltage being at the peak value when a resonant frequency of said resonant circuit corresponds to the operating frequency; and

alter a phase of the output voltage by an angle so as to generate the reference voltage, the angle being a phase difference between the open-circuit voltage and the output voltage when the resonant circuit is resonating.

6. The contactless ICPT system as claimed in claim 5, wherein said first controller includes:

a comparing unit which is coupled electrically to said reference voltage generator for receiving the reference voltage and to said resonant circuit for detecting the output voltage, and generates a phase difference signal associated with a phase difference between the reference voltage and the output voltage; and

a control unit which is coupled electrically to said comparing unit for receiving the phase difference signal, which stores a reference phase signal representing the phase difference between the open-circuit voltage and the output voltage when said resonant circuit is resonating, and which compares the phase difference signal to the reference phase signal so as to calculate and output the first control signal.

7. The contactless ICPT system as claimed in claim 2, wherein said reactance element of said resonant circuit includes:

a fixed capacitor coupled electrically to two ends of said secondary winding and providing capacitance of the parallel resonant LC circuit;

a first adjustable capacitor coupled electrically to two ends of said fixed capacitor, and coupled electrically to said first control circuit to be controlled thereby for adjusting equivalent capacitance of said first adjustable capacitor that serves as capacitance of the series resonant LC circuit; and

an adjustable inductance member which has a first end coupled electrically to one of said two ends of said fixed capacitor and a second end to be coupled electrically to one end of the load, and which is coupled electrically to said first control circuit to be controlled thereby for adjusting equivalent inductance of said adjustable inductance member that serves as inductance of the series resonant LC circuit.

8. The contactless ICPT system as claimed in claim 2, wherein said reactance element of said resonant circuit includes:

a fixed capacitor coupled electrically to two ends of said secondary winding and providing capacitance of the parallel resonant LC circuit, and component capacitance;

a first adjustable inductor coupled electrically to two ends of said fixed capacitor, and coupled electrically to said first control circuit to be controlled thereby for adjusting equivalent inductance of said first adjustable inductor, the component capacitance in combination with the equivalent inductance of said first adjustable inductor serving as capacitance of the series resonant LC circuit; and

an adjustable inductance member which has a first end coupled electrically to one of said two ends of said fixed capacitor and a second end to be coupled electrically to one end of the load, and which is coupled electrically to said first control circuit to be controlled thereby for adjusting equivalent inductance of said adjustable inductance member that serves as inductance of the series resonant LC circuit.

9. The contactless ICPT system as claimed in claim 2, wherein said reactance element of said resonant circuit includes:

an adjustable capacitor coupled electrically to two ends of said secondary winding, and coupled electrically to said first control circuit to be controlled thereby for adjusting equivalent capacitance of said adjustable capacitor that serves as a capacitance of the parallel resonant LC circuit and a capacitance of the series resonant LC circuit; and

an adjustable inductance member which has a first end coupled electrically to one end of said adjustable capacitor, and a second end to be coupled electrically to one end of the load, and which is coupled electrically to said first control circuit to be controlled thereby for adjusting equivalent inductance of said adjustable inductance member that serves as inductance of the series resonant LC circuit.

10. The contactless ICPT system as claimed in claim 7, wherein said adjustable inductance member includes:

a fixed inductor; and

an adjustable inductor connected in parallel with said fixed inductor, and coupled electrically to said first control circuit to be controlled thereby for adjusting equivalent inductance of said adjustable inductor.

11. The contactless ICPT system as claimed in claim 8, wherein said adjustable inductance member includes:

a fixed inductor; and

a second adjustable inductor connected in parallel with said fixed inductor, and coupled electrically to said first control circuit to be controlled thereby for adjusting equivalent inductance of said second adjustable inductor.

12. The contactless ICPT system as claimed in claim 9, wherein said adjustable inductance member includes:

a fixed inductor; and

an adjustable inductor connected in parallel with said fixed inductor, and coupled electrically to said first control circuit to be controlled thereby for adjusting equivalent inductance of said adjustable inductor.

13. The contactless ICPT system as claimed in claim 7, wherein said adjustable inductance member includes:

a fixed inductor; and

a second adjustable capacitor connected in parallel with said fixed inductor, and coupled electrically to said first control circuit to be controlled thereby for adjusting equivalent capacitance of said second adjustable capacitor.

14. The contactless ICPT system as claimed in claim 8, wherein said adjustable inductance member includes:

a fixed inductor; and

an adjustable capacitor connected in parallel with said fixed inductor, and coupled electrically to said first control circuit to be controlled thereby for adjusting equivalent capacitance of said adjustable capacitor.

15. The contactless ICPT system as claimed in claim 9, wherein said adjustable inductance member includes:

a fixed inductor; and

a second adjustable capacitor connected in parallel with said fixed inductor, and coupled electrically to said first control circuit to be controlled thereby for adjusting equivalent capacitance of said second adjustable capacitor.

16. The contactless ICPT system as claimed in claim 1, wherein said power receiving device includes:

a first control circuit coupled electrically to said resonant circuit, to be coupled electrically to the load, and including

a first controller which detects the output voltage of said resonant circuit, which receives a reference voltage, and which calculates and outputs a first control signal based on the reference voltage and the output voltage for controlling said resonant circuit to maintain resonance, and

a second controller which is for detecting a load voltage across the load, which stores a preset voltage, and which calculates and outputs a second control signal based on the load voltage and the preset voltage for controlling said resonant circuit such that the load voltage is substantially equal to the preset voltage.

wherein said first control circuit further includes a reference voltage generator, capacitance and inductance of the series resonant LC circuit being set to enable an initial state of the output voltage to turn on said first control circuit such that said reference voltage generator is activated, said reference voltage generator being configured to;

adjust one of the capacitance and the inductance of the series resonant LC circuit so as to vary the output voltage of said resonant circuit;

receive the output voltage when the output voltage reaches a peak value, the output voltage being at the peak value when a resonant frequency of said resonant circuit corresponds to the operating frequency; and

generate the reference voltage based on the output voltage thus received when the output voltage reaches the peak value.

17. The contactless ICPT system as claimed in claim 1, wherein said power supply device further includes:

a rectifier circuit adapted for receiving an AC signal and converting the AC signal into a direct current (DC) signal;

a frequency converter circuit coupled electrically to said rectifier circuit for receiving the DC signal and converting the DC signal into the AC current flow that has the operating frequency;

an adjustment circuit coupled electrically between said frequency converter circuit and said primary winding, and including a first adjustable reactance member, said power receiving device having input impedance when observed from said primary winding, said first adjustable reactance member being connected in series with said primary winding and being controllable to adjust equivalent reactance of said first adjustable reactance member so as to cancel out reactance of the input impedance; and

a second control circuit coupled electrically to said first adjustable reactance member for adjusting the equivalent reactance thereof.

18. The contactless ICPT system as claimed in claim 17,

wherein said adjustment circuit further includes a first sensor provided for sensing a current flowing through said primary winding and for outputting a current sensing signal related to the current thus sensed;

and

wherein said second control circuit stores a preset current signal, is coupled electrically to said first sensor for receiving the current sensing signal, and controls said first adjustable reactance member based on the current sensing signal and the preset current signal, such that the current sensing signal is caused to be substantially equal to the preset current signal.

19. The contactless ICPT system as claimed in claim 17, wherein said adjustment circuit further includes:

a second adjustable reactance member connected in parallel with said primary winding and said first adjustable reactance member that are connected in series, and coupled electrically to said second control circuit to be controlled thereby for adjusting equivalent reactance of said second adjustable reactance member.

20. The contactless ICPT system as claimed in claim 19,

wherein said adjustment circuit further includes a second sensor provided for sensing a voltage across said second adjustable reactance member and for outputting a voltage sensing signal related to the voltage thus sensed;

and

wherein said second control circuit stores a resonant voltage signal that represents a voltage of said second adjustable reactance member when said adjustment circuit, said primary winding and the input impedance resonate at the operating frequency, said second control circuit being further coupled electrically to said second sensor for receiving the voltage sensing signal, and controlling said second adjustable reactance member based on the voltage sensing signal and the resonant voltage signal, such that the voltage sensing signal is caused to be substantially equal to the resonant voltage signal.

21. The contactless ICPT system as claimed in claim 19, wherein said adjustment circuit further includes:

a third adjustable reactance member connected between one end of said second adjustable reactance member and said frequency converter circuit, and coupled electrically to said second control circuit to be controlled thereby for adjusting equivalent reactance of said third adjustable reactance member.

22. The contactless ICPT system as claimed in claim 21,

wherein said adjustment circuit further includes

a third sensor coupled electrically between output terminals of said frequency converter circuit, and provided for sensing a voltage outputted from said frequency converter circuit, and

a fourth sensor coupled electrically to one of said output terminals of said frequency converter circuit, and provided for sensing a current outputted from said frequency converter circuit;

and

wherein said second control circuit is further coupled electrically to said third sensor and said fourth sensor for respectively obtaining the voltage and the current of said frequency converter circuit, and controls said third adjustable reactance member based on the voltage and the current of said frequency converter circuit, such that the voltage and the current of said frequency converter circuit are in phase.

23. A contactless inductively coupled power transfer (ICPT) system comprising:

a power supply device including

a rectifier circuit adapted for receiving an alternating current (AC) signal and converting the AC signal into a direct current (DC) signal,

a frequency converter circuit coupled electrically to said rectifier circuit for receiving the DC signal and converting the DC signal into an AC current flow that has an operating frequency,

a primary winding which is for generating an electromagnetic field in response to the AC current flow,

an adjustment circuit coupled electrically between said frequency converter circuit and said primary winding, and including a first adjustable reactance member which is connected in series with said primary winding and which is controllable to adjust equivalent reactance of said first adjustable reactance member, and

a control circuit coupled electrically to said first adjustable reactance member for adjusting the equivalent reactance thereof; and

a power receiving device including

a secondary winding that generates an open-circuit voltage according to induction of the electromagnetic field and that is adapted for supplying electric power associated with the open-circuit voltage to a load;

wherein said power receiving device has input impedance when observed from said primary winding, the equivalent reactance of said first adjustable reactance member being adjusted so as to cancel out reactance of the input impedance.

24. The contactless ICPT system as claimed in claim 23,

wherein said adjustment circuit further includes a first sensor provided for sensing a current flowing through said primary winding and for outputting a current sensing signal related to the current thus sensed;

and

wherein said control circuit stores a preset current signal, is coupled electrically to said first sensor for receiving the current sensing signal, and controls said first adjustable reactance member based on the current sensing signal and the preset current signal, such that the current sensing signal is caused to be substantially equal to the preset current signal.

25. The contactless ICPT system as claimed in claim 23, wherein said adjustment circuit further includes:

a second adjustable reactance member connected in parallel with said primary winding and said first adjustable reactance member that are connected in series, and coupled electrically to said control circuit to be controlled thereby for adjusting equivalent reactance of said second adjustable reactance member.

26. The contactless ICPT system as claimed in claim 25,

wherein said adjustment circuit further includes a second sensor provided for sensing a voltage across said second adjustable reactance member and for outputting a voltage sensing signal related to the voltage thus sensed;

and

wherein said control circuit stores a resonant voltage signal that represents a voltage of said second adjustable reactance member when said adjustment circuit, said primary winding and the input impedance resonate at the operating frequency, said control circuit being further coupled electrically to said second sensor for receiving the voltage sensing signal, and controlling said second adjustable reactance member based on the voltage sensing signal and the resonant voltage signal, such that the voltage sensing signal is caused to be substantially equal to the resonant voltage signal.

27. The contactless ICPT system as claimed in claim 25, wherein said adjustment circuit further includes:

a third adjustable reactance member connected between one end of said second adjustable reactance member and said frequency converter circuit, and coupled electrically to said control circuit to be controlled thereby for adjusting equivalent reactance of said third adjustable reactance member.

28. The contactless ICPT system as claimed in claim 27,

wherein said adjustment circuit further includes

a third sensor coupled electrically between output terminals of said frequency converter circuit, and provided for sensing a voltage outputted from said frequency converter circuit, and

a fourth sensor coupled electrically to one of said output terminals of said frequency converter circuit, and provided for sensing a current outputted from said frequency converter circuit;

and

wherein said control circuit is further coupled electrically to said third sensor and said fourth sensor for respectively obtaining the voltage and the current of said frequency converter circuit, and controls said third adjustable reactance member based on the voltage and the current of said frequency converter circuit, such that the voltage and the current of said frequency converter circuit are in phase.