NON-CONTACT POWER FEEDER

• US 20100033156A1
• Filed: 08/07/2006
• Published: 02/11/2010
• Est. Priority Date: 09/01/2005
• Status: Active Grant

• Current Assignee: National University Corporation Saitama University
• Original Assignee: National University Corporation Saitama University
• Inventors: Abe, Shigeru, Kaneko, Hiroyoshi
• Granted Patent: US 8,164,925 B2
• Time in Patent Office: Days
• US Class Current: 323/305
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/20 using microwaves or radio frequency waves
• CPC Class Codes: H02M 3/3378 in a push-pull configuration of the parallel type H02M3/3374 takes precedence

Abstract

[Problems] To provide a non-contact power feeder that is high efficient and high power factor and has no load dependence.

[Means for Solving Problems] A series capacitor Cs1 is connected to a primary winding 1 driven by an AC power supply 3 and a parallel capacitor Cp2 is connected to a secondary winding 2. The capacitance Cp is set to Cp≈1/{2πf0×(x0+x2)} and the capacitance Cs converted to the primary side is set to Cs≈(x0+x2)/{2πf0×(x0×x1+x1×x2+x2×x0)}, where f0 is the frequency of the power supply, x1 is a primary leakage reactance of the primary winding 1, x2 is a secondary leakage reactance of the secondary winding 2 converted to the primary side and x0 is an excitation reactance converted to the primary side. By setting Cp and Cs to the above values, the transformer of the non-contact power feeder is substantially equivalent to an ideal transformer. If it is driven by a voltage type converter, the output voltage (=load voltage) becomes substantially constant voltage regardless of the load. In case of a resistive load (ZL=R), the power factor of the power supply output always remains 1 even if the load may vary.

Claims

1. A non-contact power feeder for supplying power by electromagnetic induction from a primary winding driven by an AC power supply to a secondary winding disposed with an air gap between the primary winding, further comprising:

a series capacitor connected in series with one of the primary winding and the secondary winding and a parallel capacitor connected in parallel with the other one of the primary winding and the secondary winding; and

the capacitance value Cp of the parallel capacitor converted to the primary side is set to;

Cp≈

1/{2π

f0×

(xo+X)}

and the capacitance value Cs of the series capacitor converted to the primary side is set to;

Cs≈

(x0+X)/{2π

f0×

(x0×

x1+x1×

x2+x2×

x0)}

where, f0 is the frequency of the AC power supply, x1 is the primary leakage reactance at the frequency F0 of the transformer comprising the primary winding and the secondary winding, x2 is the secondary leakage reactance converted to the primary side, x0 is the excitation reactance and X is x1 in case of connecting the parallel capacitor in parallel with the primary winding or x2 in case of connecting in parallel with the secondary winding.

2. A non-contact power feeder of claim 1, wherein if

Cs0=(x0+X)/{2π

f0×

(x0×

x1+x1×

x2+x2×

x0)},

the capacitance value Cs of the series capacitor is set within the following range;

(1−

0.4)Cs0≦

Cs≦

(1+0.4)Cs0.

3. A non-contact power feeder of claim 2, wherein if

Cp0=1/{2π

f0×

(x0+X)},

the capacitance value Cp of the parallel capacitor is set within the following range;

(1−

0.4)Cp0≦

Cp≦

(1+0.4)Cp0.

7. A non-contact power feeder of claim 1, wherein at least one of the primary winding and the secondary winding is wound around a core.

9. A non-contact power feeder of claim 1, wherein a self-exciting converter is disposed through an inductor between the parallel capacitor Cp connected to the secondary winding and the load to which a DC power is supplied, and the power factor of the secondary side AC output that is outputted to the load through the parallel capacitor Cp is controlled by the self-exciting converter.

10. A non-contact power feeder of claim 9, wherein the amplitude and the phase of the AC voltage on the AC input terminal of the self-exciting converter are controlled based on the amplitude and the phase of the secondary side AC output voltage as well as the current flowing through the inductor.

11. A non-contact power feeder of claim 9, wherein the self-exciting converter is a PWM (Pulse Width Modulation) converter.

12. A non-contact power feeder of claim 9, wherein the self-exciting converter is a voltage type pulse width control converter.

13. A non-contact power feeder of claim 1, wherein a PFC (Power Factor Correction) converter is disposed between the parallel capacitor Cp connected to the secondary winding and a load to which a DC power is supplied, and the power factor of the secondary side AC output that is outputted to the load through the parallel capacitor Cp is controlled by the PFC converter.

14. A non-contact power feeder of claim 13, wherein a circuit comprising a diode bridge and a step-up chopper is employed as the PFC converter.

4. A non-contact power feeder for feeding power by electromagnetic induction from a primary winding driven by an AC power supply to a secondary winding disposed with an air gap between the primary winding, further comprising:

a series capacitor connected in series with the primary winding, a parallel capacitor connected in parallel with the secondary winding, an inductor connected in series between the secondary winding and the parallel capacitor and a load connected in parallel with the parallel capacitor; and

when frequency of the AC power supply is f0, primary leakage reactance, secondary leakage reactance converted to the primary side, exciting reactance converted to the primary side of a transformer comprising the primary winding and the secondary winding are respectively x1, x2 and x0 and reactance of the inductor converted to the primary side is Xa,

the capacitance value Cs of the series capacitor is set to;

Cs(x0+Y)/{2π

f0×

(x0×

x1+x1×

Y+Y×

x0)}

and the capacitance value Cp of the parallel capacitor is set to form a resonance circuit together with the secondary winding and the inductor,

where, f0 is the frequency of the AC power supply, x1 is the primary leakage reactance at the frequency f0 of the transformer comprising the primary winding and the secondary winding, x2 is the secondary leakage reactance converted to the primary side, x0 is the excitation reactance converted to the primary side, xa is the reactance of the inductor converted to the primary side and Y=x2+xa.

6. A non-contact power feeder of claim 4, when

Cs0=(x0+Y)/{2π

f0×

(x0×

x1+x1×

Y+Y×

x0)},

the capacitance Cs of the series capacitor is set within the following range;

(1−

0.4)Cs0≦

Cs≦

(1+0.4)Cs

5. A non-contact power feeder for feeding power by electromagnetic induction from a primary winding driven by an AC power supply to a secondary winding disposed with an air gap between the primary winding, further comprising:

a series capacitor connected in series with the primary winding, a parallel capacitor connected in parallel with the secondary winding, a secondary side series capacitor connected between the secondary winding and the parallel capacitor, and a load connected in parallel with the parallel capacitor,

wherein the capacitance Cs of the series capacitor is set to;

Cs≈

(x+Y)/{2π

f0×

(x0×

x1+x1×

Y+Y×

x0)},

And the capacitances of the parallel capacitor and the secondary side series capacitor are set so that the overall capacitance Cp of the series connection of the parallel capacitor and the secondary side series capacitor constitutes a resonance circuit together with the secondary winding,

where, f0 is the frequency of the AC power source, x1 is the primary leakage reactance of the transformer comprising the primary winding and the secondary winding, x2 is the secondary leakage reactance converted to the primary side, x0 is the excitation reactance converted to the primary side, and Y is x2.

8. A non-contact power feeder for feeding power by electromagnetic induction from a primary winding driven by an AC power supply to m (m>

1) secondary windings of identical shape disposed with an air gap between the primary winding, further comprising;

a series capacitor Cs connected in series with the primary winding and m parallel capacitors connected respectively in parallel with the secondary windings,

wherein the capacitance Cp of each of the parallel capacitors connected to the respective secondary winding and converted to the primary side is set to;

Cp≈

1/{2π

f0×

(x0+x2)}

and the capacitance Cs of the series capacitor is set to;

Cs≈

(x0+x2)/{m×

2π

f0×

(x0×

x1/m+x1×

x2/m+x2×

x0)},

where, f0 is the frequency of the AC power supply, x1 is the primary leakage reactance at the frequency f0 of each of the m transformers comprising the primary winding and the secondary windings, x2 is the secondary leakage reactance converted to the primary side and x0 is the excitation reactance converted to the primary side.