JP2012105503A - Non-contact power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-contact power supply device suppressing a change of input impedance viewed from an output side of an AC power supply side even under a condition that a coupling state changes.SOLUTION: The non-contact power supply device includes secondary winding 201 to which power is supplied from primary winding 101 with an AC power supply. A characteristic of an absolute value of the impedance to a frequency of Z1 has a frequency of a fundamental wave component between a frequency which is the nearest to a frequency of the fundamental wave component of the AC power supply and takes a maximum value and a frequency which is the nearest to the frequency of the fundamental wave component and takes a minimum value, and the characteristic of the absolute value of the impedance to the frequency of Z2 has the maximum value near the frequency of the fundamental wave component. Provided that Z1 shows the impedance of only a primary side viewed from the output side of the AC power supply, and Z2 shows the impedance of only a secondary side viewed from a load side connected to the secondary winding.

Description

  The present invention relates to a non-contact power feeding device.

  A non-contact power feeding device that supplies electric power from a primary side to a secondary side provided on a moving body based on a mutual induction action of electromagnetic induction, with an air gap and in a non-contact proximity corresponding position. As the next-side power feeding circuit, one in which a series capacitor for resonance tuning is arranged in each parallel coil and the capacitor is connected in parallel to each coil is known. (Patent Document 1)

JP 2010-40699 A

  However, in the conventional non-contact power supply apparatus, since the capacitor is set on the assumption that the coupling coefficient between the primary side coil and the secondary side coil is constant, the coupling coefficient changes. In such a case, there has been a problem that the input impedance as viewed from the AC power supply side changes greatly.

  Therefore, the present invention provides a non-contact power feeding device that suppresses a change in input impedance viewed from the output side on the AC power source side even under a condition where the coupling state changes.

  In the characteristics of the absolute value of the impedance only on the primary side viewed from the output side of the AC power supply, the present invention is closest to the frequency of the fundamental wave component of the AC power supply, and has the highest frequency and the frequency of the fundamental wave component. In the characteristic of the absolute value of the impedance only on the secondary side viewed from the load side connected to the secondary winding, the fundamental wave component is set so that the frequency of the fundamental wave component is close to the frequency that takes the minimum value. The above-mentioned problem is solved by having a maximum value in the vicinity of the frequency.

  According to the present invention, when the coupling coefficient changes within a predetermined range, the characteristic of the absolute value of the input impedance with respect to the frequency of the fundamental wave component becomes a characteristic that changes in the vicinity of the predetermined impedance value. Even under the condition that changes, the change in the input impedance viewed from the output side on the AC power supply side can be suppressed.

It is an electric circuit diagram of the non-contact electric power feeder of this example. It is the top view and perspective view which show the state which the primary winding and secondary winding of FIG. 1 opposed. It is the top view and perspective view which show the state which the primary winding and secondary winding of FIG. 1 opposed, and is a figure which shows the case where it shift | deviates to the X-axis direction. 3 is a graph showing a change in coupling coefficient for the secondary winding 201 in the X-axis direction (Y-axis direction) and the Z-axis direction shown in FIGS. 2a and 2b. It is a graph which shows the characteristic of the coupling coefficient with respect to the distance of the primary winding and secondary winding of FIG. It is a graph which shows the input impedance characteristic with respect to a coupling coefficient in the conventional non-contact electric power feeder. It is a graph which shows the characteristic of the absolute value of input impedance with respect to equivalent load resistance in the conventional non-contact electric power feeder. FIG. 2 is a circuit diagram showing an equivalent circuit on the primary side of FIG. 1. It is a circuit diagram of the circuit of the primary side among the circuit diagrams of the non-contact electric power feeding part of FIG. FIG. 2 is a circuit diagram of a secondary circuit in the circuit diagram of the non-contact power feeding unit of FIG. 1. It is a graph which shows the characteristic of the absolute value of the impedance with respect to the frequency in the circuit of FIG. 7a. It is a graph which shows the characteristic of the absolute value of the impedance with respect to the frequency in the circuit of FIG. 7b. 2 is a graph illustrating input impedance characteristics with respect to a coupling coefficient in the non-contact power feeding apparatus of FIG. 1. It is a circuit diagram which shows the equivalent circuit of the non-contact electric power feeding part and load part of FIG. In the complex plane diagrams showing the poles and zeros of the input impedance of the non-contact power supply unit of FIG. 1 (Z _in). In the complex plane diagrams showing the poles and zeros of the input impedance of the non-contact power supply unit of FIG. 1 (Z _in). It is a graph which shows the characteristic of the absolute value of the impedance with respect to the frequency in the circuit of FIG. 7a. It is a graph which shows the characteristic of the impedance absolute value with respect to the frequency in the circuit of FIG. 7a. 2 is a graph showing characteristics of an absolute value of input impedance with respect to a coupling coefficient in the non-contact power feeding unit of FIG. 1. 2 is a graph showing characteristics of output voltage with respect to output current in the high-frequency AC power supply unit of FIG. 1. 2 is a graph showing characteristics of output voltage with respect to output current in the high-frequency AC power supply unit of FIG. 1. 2 is a graph showing characteristics of an absolute value of input impedance with respect to a coupling coefficient in the non-contact power feeding unit of FIG. 1. 2 is a graph showing characteristics of an absolute value of input impedance with respect to an equivalent load resistance in the non-contact power feeding unit of FIG. 1. In the non-contact power feeding device of FIG. 1 (a), in the non-contact power feeding device of the output power graph illustrating the properties of a (P _{out) (b)} Figure 1 for the coupling coefficient (kappa), a predetermined power condition is satisfied, the coupling coefficient Graph showing the range of (κ) It is a circuit diagram of the non-contact electric power feeding part of the non-contact electric power feeder which concerns on other embodiment of invention. It is a graph which shows the characteristic of the absolute value of the input impedance with respect to the frequency in the circuit of the primary side among the circuits of FIG. It is a circuit diagram of the non-contact electric power feeding part of the non-contact electric power feeder which concerns on other embodiment of invention. It is a graph which shows the characteristic of the absolute value of the input impedance with respect to the frequency in the circuit of the primary side among the circuits of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<< First Embodiment >>
As an example of a non-contact power supply circuit device according to an embodiment of the invention, a non-contact power supply device used together with a battery for a vehicle such as an electric vehicle and a power load will be described.

  FIG. 1 shows an electric circuit diagram of the non-contact power feeding device. The non-contact power feeding device according to the present embodiment has a high-frequency AC power supply unit 6, a non-contact power feeding unit 5 that performs non-contact power feeding of power output from the high-frequency AC power circuit 6, and the non-contact power feeding unit 5. And a load section 7 to be supplied.

  The high-frequency AC power supply unit 6 is connected to the three-phase AC power supply 64, the three-phase AC power supply 64, the rectifier 61 that rectifies the three-phase AC to DC, and the rectifier 61 via the smoothing capacitor 62 to be rectified. And a voltage type inverter 63 that reversely converts the current into high frequency power. The rectifier 61 connects the diode 61a and the diode 61b, the diode 61c and the diode 61d, and the diode 61e and the diode 61f in parallel, and connects the output of the three-phase AC power supply 64 to each intermediate connection point. The voltage type inverter 63 connects in parallel a series circuit of a switching element 63b similar to a switching element 63a that connects a diode to a MOSFET power transistor or the like in antiparallel, and a series circuit of a similar switching element 63c and switching element 63d. Then, it is connected to the rectifier 61 through the smoothing capacitor 62. Then, an intermediate connection point between the switching element 63a and the switching element 63b and an intermediate connection point between the switching element 63c and the switching element 63d are connected to the power transmission circuit unit 3 that is the primary side of the non-contact power feeding unit 5, respectively. The voltage type inverter 63 supplies AC power of about several k to 100 kHz to the non-contact power feeding unit 50.

Here, the output waveform output from the high-frequency AC power supply unit 6 to the non-contact power supply unit 5 is a waveform that changes periodically, and the frequency of the output waveform is f ₀ . When the output waveform includes distortion (or when the output waveform is, for example, a rectangular wave), the frequency of the basic sine wave included in the periodic function of the waveform including distortion is the frequency (f ₀ ). Become. Hereinafter, in the present invention, these frequencies are collectively referred to as the frequency (f ₀ ) of the fundamental wave component of the high-frequency AC power supply unit 6. The high-frequency AC power supply unit 6 does not necessarily have to be the circuit shown in FIG. 1 and may be another circuit.

  The non-contact power feeding unit 5 includes a power transmission circuit unit 3 that is an input side of the transformer and a power receiving circuit unit 4 that is an output side of the transformer. The power transmission circuit unit 3 includes a primary winding 101, a capacitor 102 connected in series to the primary winding 101, and a capacitor 103 connected in parallel to the primary winding 101. A secondary winding 201 and a capacitor 202 connected in parallel to the secondary winding 201 are included.

  The load unit 7 includes a rectification unit 71 that rectifies AC power supplied from the non-contact power supply unit 5 into a direct current, and a load 72 that is connected to the rectification unit 71. The rectifying unit 71 connects the diode 71a and the diode 71b, and the diode 71c and the diode 71d in parallel, and connects the output of the power receiving circuit unit 4 to each intermediate connection point. Then, the output of the rectifying unit 71 is connected to the load 72.

  Next, when the non-contact power supply circuit device shown in FIG. 1 is provided in a vehicle and a parking lot using FIGS. 2 a, 2 b, 3, and 4, the coupling coefficient of the primary winding 101 and the secondary winding 201 ( κ) will be described.

  In this example, the power receiving circuit unit 4 and the load unit 7 including the secondary winding 201 are provided in a vehicle, for example, and the power transmission circuit unit 3 including the primary winding 101 and the high-frequency AC power supply 6 are provided on the ground side, for example, in a parking lot. In the case of an electric vehicle, the load 72 corresponds to, for example, a secondary battery. The secondary winding 201 is provided, for example, in a vehicle chassis. Then, the driver of the vehicle parks in the parking lot so that the secondary winding 201 is above the primary winding 101, and electric power is supplied from the primary winding 101 to the secondary winding 201, and the load 72 The included secondary battery is charged.

  2a and 2b are a plan view a) showing a state in which the primary winding 101 and the secondary winding 201 face each other, and perspective views b) and c). 2a and 2b, the X axis and the Y axis indicate the planar directions of the primary winding 101 and the secondary winding 201, and the Z axis indicates the height direction. For the purpose of this description, the primary winding 101 and the secondary winding 201 are both of the same circular shape, but this example does not necessarily need to be circular, and the primary winding 101 and the secondary winding. It is not necessary to make 201 the same shape.

  Now, as shown in FIG. 2a, the vehicle may be parked in the parking lot so that the secondary winding 201 matches the primary winding 101 in the X-axis and Y-axis directions, which are planar directions. 2b, the relative positions of the primary winding 101 and the secondary winding 201 may be shifted in the plane direction. Further, since the height of the vehicle varies depending on the type of vehicle and the load, the distance in the height direction Z between the primary winding 101 and the secondary winding 201 also varies depending on the vehicle height.

  When the power supplied from the high frequency AC power supply 6 to the primary winding 101 is constant, the efficiency of the power received by the secondary winding 201 is such that the secondary winding 201 matches the primary winding 101 ( (Corresponding to the state of FIG. 2 a) is the highest and becomes lower when the center point of the secondary winding 201 is farther from the center point of the primary winding 101.

  FIG. 3 shows a change in the coupling coefficient for the secondary winding 201 in the X-axis direction (Y-axis direction) and the Z-axis direction shown in FIGS. 2a and 2b. As shown in FIG. 3, when the center of the primary winding 1 and the center of the secondary winding 2 coincide, the leakage magnetic flux between the primary winding 1 and the secondary winding 2 is small, and the X axis of FIG. Corresponds to zero, and the coupling coefficient κ increases. On the other hand, as shown in FIG. 2b with respect to FIG. 2a, when the positions of the primary winding 1 and the secondary winding 2 are shifted in the X-axis direction, the leakage flux increases, and as shown in FIG. κ becomes smaller. Further, when the deviation in the Z-axis (height) direction between the primary winding 1 and the secondary winding 2 increases, the coupling coefficient κ decreases.

  FIG. 4 is a graph showing the characteristic of the coupling coefficient with respect to the distance (L) between the primary winding 101 and the secondary winding 201. However, the distance (L) is expressed by equation (1).

図４に示すように、距離（Ｌ）が大きくなると、漏れ磁束が多くなるため、結合係数（κ）は小さくなる。

As shown in FIG. 4, as the distance (L) increases, the leakage flux increases, so the coupling coefficient (κ) decreases.

  By the way, in the conventional non-contact electric power feeder, the circuit design of the non-contact electric power feeding part is performed by making a coupling coefficient into a fixed value. Therefore, as described above, when the relative position between the coils of the power feeding part is shifted and the coupling coefficient (κ) is changed, the input of the power feeding circuit including the non-contact coil viewed from the output side of the AC power supply Impedance changes greatly. Here, the change of the impedance characteristic with respect to the coupling coefficient (κ) in the conventional non-contact power feeding apparatus will be described with reference to FIG. FIG. 5a is a graph showing the characteristics of the absolute value of the input impedance with respect to the coupling coefficient (κ) in the conventional non-contact power feeding device. The input impedance is an impedance viewed from the output side of the AC power supply, and is an impedance at the frequency of the fundamental wave component of the AC power supply. Graph a shows characteristics of a circuit (hereinafter referred to as conventional circuit a) in which a capacitor is designed to be tuned with a predetermined coupling coefficient in the circuit disclosed in Japanese Patent Application Laid-Open No. 2010-40669. Shows characteristics of a circuit (hereinafter referred to as a conventional circuit b) in which a capacitor is designed to be tuned with a predetermined coupling coefficient in the circuit disclosed in Japanese Patent Application Laid-Open No. 2007-534289.

  As shown in graph a of FIG. 5a, in the conventional circuit a, when the coupling coefficient is small, the absolute value of the input impedance increases, and as the coupling coefficient increases, the absolute value of the input impedance decreases. Further, as shown in the graph b, in the conventional circuit b, when the coupling coefficient is small, the absolute value of the input impedance increases, and as the coupling coefficient increases, the absolute value of the input impedance decreases. That is, since the conventional circuit a and the conventional circuit b are designed on the assumption that the coupling coefficient of the coil which is a non-contact power feeding part is constant, if the coupling coefficient changes, the input impedance of the power feeding circuit increases. Change. The graph c indicates the absolute value of the impedance of the AC power supply, and details will be described later.

  Next, changes in the input impedance of the power feeding circuit accompanying changes in the equivalent load resistance (R) in the conventional circuit a and the conventional circuit b will be described using FIG. 5B. FIG. 5b shows the characteristics of the absolute value of the input impedance with respect to the equivalent load resistance (R) in the conventional circuits a and b. The input impedance is an impedance viewed from the output side of the AC power supply, and is an impedance at the frequency of the fundamental wave component of the AC power supply. The equivalent load resistance (R) is a resistance of a load electrically connected to the secondary coil in the non-contact power supply apparatus, and the load includes a battery. When the remaining capacity of the battery is small, the equivalent load resistance (R) is small, and when the remaining capacity of the battery is large, the equivalent load resistance (R) is high.

  As shown in graph a of FIG. 5b, in the conventional circuit a, when the equivalent load resistance is small, the absolute value of the input impedance increases, and as the equivalent load resistance increases, the absolute value of the input impedance decreases. Further, as shown in the graph b, in the conventional circuit b, when the equivalent load resistance is small, the absolute value of the impedance increases, and as the equivalent load resistance increases, the absolute value of the impedance decreases. That is, in the conventional circuit a and the conventional circuit b, when the equivalent load resistance changes, the input impedance of the power feeding circuit greatly changes. The graph c indicates the absolute value of the impedance of the AC power supply, and details will be described later.

Next, the relationship between the impedance (Zc) of the AC power supply and the input impedance (Z in — _c ) of the power feeding circuit including a non-contact coil will be described with reference to FIG. FIG. 6 is a circuit diagram of an equivalent circuit on the primary side of the non-contact power feeding device. The AC power source 601 is an AC power source provided on the primary side of the non-contact power feeding device, and supplies AC power to the primary side coil. Vc indicates an AC voltage of the AC power supply 601, and Ic indicates an AC current output from the AC power supply 601. The impedance 602 is an input impedance (Z in — _c ) of a power feeding circuit including a non-contact coil. The rated value of the AC power supply 601 is determined in advance. For example, it is assumed that the maximum voltage of the AC power supply 601 is 300 [V], the maximum current is 30 [A], and the maximum power is 9 [kW]. .

A case where the input impedance (Z in — _c ) of the impedance 602 is 1 [Ω] will be described. When 300 [V], which is the maximum voltage of the AC power supply, is applied to the impedance 602, a current of 300 [A] flows through the power supply circuit having the impedance 602. However, since the maximum current of the AC power supply 601 is 30 [A], the current flowing through the power supply circuit is 30 [A], and the voltage of the power supply circuit is 30 [V]. For this reason, the power supplied to the power supply circuit having the impedance 602 is 900 [W], and the maximum power of the AC power supply 601 cannot be supplied to the power supply circuit.

A case where the input impedance (Z in — _c ) of the impedance 602 is 100 [Ω] will be described. When 300 [V], which is the maximum voltage of the AC power supply, is applied to the impedance 602, a current of 3 [A] flows through the power supply circuit having the impedance 602. Although the maximum current of the AC power supply 601 is 30 A, since the input impedance (Z in — _c ) is high, the current flowing through the power feeding circuit is 3 [A]. The voltage of the power feeding circuit is 300 [V]. For this reason, the power supplied to the power supply circuit having the impedance 602 is 900 [W], and the maximum power of the AC power supply 601 cannot be supplied to the power supply circuit.

A case where the input impedance (Z in — _c ) of the impedance 602 is 10 [Ω] will be described. When 300 [V], which is the maximum voltage of the AC power supply, is applied to the impedance 602, a current of 30 [A] flows through the power supply circuit having the impedance 602, and the maximum current of the AC power supply 601 flows. Therefore, the power supplied to the power supply circuit having the impedance 602 is 900 [W], and the maximum power of the AC power supply 601 can be supplied to the power supply circuit.

That is, when the input impedance (Z in — _c ) of the impedance 602 changes with respect to the impedance of the AC power supply 601, the maximum power of the AC power supply 601 cannot be efficiently supplied to the power feeding circuit. As shown in FIGS. 5a and 5b, the input impedances of the conventional circuits a and b greatly change with respect to the impedance of the AC power supply (see graph c), and therefore the maximum power of the AC power supply 601 is efficiently fed. It cannot be supplied to the circuit.

  Therefore, in the non-contact power feeding device of this example, only the primary side impedance characteristic seen from the output side of the high-frequency AC power supply circuit 6 and the secondary side seen from the load 7 side connected to the secondary winding 201 are used. By setting the conditions for the inductances of the primary winding 101 and the secondary winding 201 and the capacitances of the capacitors 102, 103, and 202 so that the impedance characteristics are as shown below, The change of the input impedance viewed from the output side of the high-frequency AC power supply circuit 6 is suppressed under the condition that the coupling state changes.

First, impedance (Z ₁ ) and impedance (Z ₂ ) in the non-contact power feeding device of this example will be described. As shown in FIG. 7a, the impedance (Z ₁ ) is the impedance of only the primary side viewed from the high-frequency AC power supply 6 side (power transmission side) with the coupling coefficient set to zero in the circuit shown in FIG. Further, as shown in FIG. 6b, the impedance (Z ₂ ) is an impedance on the secondary side only when viewed from the load unit 7 side (power receiving side) with the coupling coefficient being zero in the circuit shown in FIG. FIG. 7A is a circuit diagram for explaining the impedance (Z ₁ ), showing a circuit only on the primary side of the non-contact power feeding section 5, and FIG. 7B is a circuit diagram for explaining the impedance (Z ₂ ). The circuit on the secondary side of the non-contact power feeding unit 5 is shown.

7a and 7b, the electric capacity of the capacitor 102 is C _1s , the electric capacity of the capacitor 103 is C _1p , the inductance of the primary winding 101 is L _1, and the electric capacity of the capacitor 202 is C 1 and _2p, the inductance of the secondary winding 201 and _{L 2.}

In the contactless power supply device of this example, the absolute value characteristics of the impedance (Z ₁ ) and the impedance (Z ₂ ) have the characteristics shown in FIGS. 8a and 8b, respectively. That is, as shown in FIG. 8a, the absolute value characteristic of the impedance (Z ₁ ) has a frequency (f ₁ ) that takes a minimum value (Z _MIN ) and a frequency (f ₂ ) that takes a maximum value (Z _MAX ). In between, it has the frequency (f ₀ ) of the fundamental wave component of the high-frequency AC power supply circuit 6. The frequency (f ₁ ) is the frequency closest to the frequency (f ₀ ) among the resonance frequencies of the impedance (Z ₁ ), and the frequency (f ₂ ) is the highest frequency among the resonance frequencies of the impedance (Z ₁ ). The frequency is close to (f ₀ ). The frequency (f ₂ ) is higher than the frequency (f ₁ ). In other words, the impedance characteristics of the _{(Z 1),} the frequency _{(f 1)} a maximum value of the minimum value _{(Z MIN)} the frequency of the _{(Z MAX) (f 2)} , a property that sandwich the frequency _{(f 0).}

Further, as shown in FIG. 8b, the characteristic of the absolute value of the impedance (Z ₂ ) has a maximum value (Z _MAX ) in the vicinity of the frequency (f ₀ ) of the fundamental wave component of the high-frequency AC power supply circuit 6. The frequency (f ₃ ) corresponding to the maximum value (Z _MAX ) is set near the frequency (f ₀ ). Note that the frequency (f ₃ ) is not necessarily equal to the frequency (f ₀ ). For example, a deviation between the frequency (f ₃ ) and the frequency (f ₀ ) due to an error in circuit design is allowed. At least, in the characteristic of the absolute value of the impedance (Z _2), at a low frequency band than the frequency (f _0), as the frequency increases, the absolute value of the impedance (Z ₂₎ rises towards the frequency (f ₀₎ In the frequency band higher than the frequency (f ₀ ), the absolute value of the impedance (Z ₂ ) only needs to decrease as the frequency decreases.

  Next, the electric capacities of the capacitors 102, 103, and 202 and the inductances of the primary winding 101 and the secondary winding 201 in this example will be described.

With the circuit shown in FIG. 7b, the resonance frequency (f ₃ ) of the impedance (Z ₂ ) is expressed by equation (2).

そして、共振周波数（ｆ_３）は、交流電源回路６の基本波成分の周波数（ｆ_０）の付近に設定されるため、ｆ_３＝ｆ_０とすると、コンデンサ２０２の電気容量（Ｃ_２ｐ）は、式（３）により表される。

Since the resonance frequency (f ₃ ) is set in the vicinity of the frequency (f ₀ ) of the fundamental wave component of the AC power supply circuit 6, when f ₃ = f ₀ , the electric capacity (C _2p ) of the capacitor 202 is , Represented by equation (3).

すなわち、交流電源回路６の基本波成分の周波数（ｆ_０）に対して、インダクタンス（Ｌ_２）及び電気容量（Ｃ_２ｐ）を式（３）に満たすように設定することで、図８ｂに示すような特性を得ることができる。また、共振周波数（ｆ_３）を交流電源回路６の基本波成分の周波数（ｆ_０）の付近に設定することで、非接触給電部５の二次側で受電するために必要な電流を抑えることができる。

That is, by setting the inductance (L ₂ ) and the electric capacity (C _2p ) to satisfy the expression (3) with respect to the frequency (f ₀ ) of the fundamental wave component of the AC power supply circuit 6, FIG. Such characteristics can be obtained. Further, by setting the resonance frequency (f ₃ ) in the vicinity of the frequency (f ₀ ) of the fundamental wave component of the AC power supply circuit 6, a current necessary for receiving power on the secondary side of the non-contact power feeding unit 5 is suppressed. be able to.

With the circuit shown in FIG. 7a, the resonance frequency (f ₁ ) and the resonance frequency (f ₂ ) of the impedance (Z ₁ ) are expressed by the equations (4) and (5), respectively.

上記の通り、基本波成分の周波数（ｆ_０）は共振周波数（ｆ_１）より高く、基本波成分の周波数（ｆ_０）は共振周波数（ｆ_２）より低いため、ｆ_１＜ｆ_０＜ｆ_２が成り立ち、各周波数に式（３）〜式（５）を代入し展開すると、式（６）が得られる。

As described above, since the frequency (f ₀ ) of the fundamental wave component is higher than the resonance frequency (f ₁ ) and the frequency (f ₀ ) of the fundamental wave component is lower than the resonance frequency (f ₂ ), f ₁ <f ₀ <f _When Formula ₂ is established and Formulas (3) to (5) are assigned to each frequency and expanded, Formula (6) is obtained.

そして、式（６）を展開することで、式（７）が得られる。

Then, expression (7) is obtained by expanding expression (6).

すなわち、式（３）を満たすように設定された、インダクタンス（Ｌ_２）及び電気容量（Ｃ_２ｐ）を用いて、式（６）又は式（７）を満たすように、インダクタンス（Ｌ_１）、電気容量（Ｃ_１ｐ）及び電気容量（Ｃ_１ｓ）を設定することで、図８ａに示すような特性を得ることができる。

That is, using the inductance (L ₂ ) and the capacitance (C _2p ) set to satisfy the expression (3), the inductance (L ₁ ), so as to satisfy the expression (6) or the expression (7), By setting the electric capacity (C _1p ) and the electric capacity (C _1s ), characteristics as shown in FIG. 8a can be obtained.

Therefore, the electric capacity (C _1s ), the electric capacity (C _1p ), the inductance (L ₁ ), the inductance (L) so as to satisfy the expressions (3) and (6) or the expressions (3) and (7). By setting L ₂ ) and capacitance (C _2p ), the impedance (Z ₁ ) characteristic and the impedance (Z ₂ ) characteristic shown in FIG. 8 can be obtained.

Next, the characteristics of the input impedance (Z _in ) of the contactless power feeding device of this example will be described with reference to FIG. FIG. 9 shows the characteristics of the absolute value of the input impedance (Z _in ) with respect to frequency. κ _{1 to} κ ₄ indicate coupling coefficients, where κ ₁ is the smallest coupling coefficient and κ ₄ is the largest coupling coefficient. The input impedance (Z _in ) indicates the input impedance of the non-contact power feeding unit 5 viewed from the output side of the high-frequency AC power supply circuit 6.

As shown in FIG. 9, when the coupling coefficient (κ) changes within the range of κ ₁ to κ ₄ , the input impedance (Z _in ) with respect to the frequency (f ₀ ) of the fundamental wave component of the high-frequency AC power supply circuit 6. Is an absolute value (| Z in _{— s} |). That is, by the secondary winding 201 the relative position of the to the primary winding 101 is shifted, when the coupling coefficient (kappa) is varied in the range of kappa ₄ from kappa _1, the absolute value of the input impedance (| Z _{in_s} |) takes a constant value, or the input impedance absolute value _{(| Z in_s |)} is to vary within a small range of change, the change of the input impedance _{(Z in)} for a frequency _{(f 0)} is suppressed . Thereby, in this example, when the coupling coefficient changes due to the impedance (Z ₁ ) and the impedance (Z ₂ ) having the characteristics shown in FIGS. 7a and 7b, the input impedance (f ₀ ) with respect to the frequency (f ₀ ) A change _in the absolute value of Z _in ) can be suppressed. When the coupling coefficient (κ) changes within the range of κ ₁ to κ ₄ , the absolute value of the input impedance (Z _in ) with respect to the frequency (f ₀ ) is the absolute value (| Z _{in_s} |) does not have to be a constant value, and may be changed by a value in the vicinity of the absolute value (| Z _{in_s} |).

Next, the locus of the poles and zeros of the input impedance (Z _in ) will be described with reference to FIGS. 10a to 10c. FIG. 10a shows an equivalent circuit of the non-contact power feeding unit 5 and the load unit 7, and FIG. 10b shows the locus of the poles and zeros of the input impedance (Z _in ) when the coupling coefficient (κ) is changed. 10c is in the case of changing the equivalent load resistance (R), indicating the locus of the poles and zeros of the input impedance (Z _in).

When the load unit 7 is replaced with an equivalent load resistance 701 (R), an equivalent circuit of the non-contact power feeding unit 5 and the load unit 7 is represented by the circuit of FIG. The equivalent load resistance 701 (R) includes the resistance of a battery (not shown) included in the load 72, and the resistance value of the battery changes depending on the state of charge (SOC) of the battery. Therefore, the resistance value of the equivalent load resistance 701 (R) is not always a constant value, but changes according to the state of the battery or the like. Based on the equivalent circuit shown in FIG. 10a, the input impedance characteristic (Z _in ) viewed from the output side of the high-frequency AC power supply circuit 6 is expressed by the equation (8) when expressed using the Laplace operator (s).

式（８）に示すＺ_ｉｎを、回路特性に影響が大きい代表根近似を行うことで、式（９）により示される。

Z _in shown _in Expression (8) is represented by Expression (9) by performing representative root approximation that has a large influence on circuit characteristics.

ただし、Ａは回路パラメータからなる係数を、λは極を、γは零点を示す。

A is a coefficient composed of circuit parameters, λ is a pole, and γ is a zero point.

When the coupling coefficient (κ) is increased from near zero, the poles and zeros draw a locus as shown in FIG. 10b. However, the pole 1 shown in FIG. 10b is a pole (not including zero) having a value closest to the imaginary axis among the poles of the formula (9), and the zero is the zero of the formula (9). Indicates the zero point closest to the imaginary axis. The dotted arrows indicate the directions of the trajectories of the pole 1 and the zero point when the coupling coefficient (κ) is increased discretely. As shown in FIG. 10b, the pole 1 and the zero point draw a symmetrical trajectory with the dotted line as a boundary while moving away from the imaginary axis as the coupling coefficient (κ) increases. The dotted line indicates a straight line that takes the drive point as an imaginary value, and the drive point (imaginary value of the point) is a value (2πf ₀ ) corresponding to the frequency of the fundamental wave component. That is, the pole 1 and the zero point take a locus symmetrical with respect to the imaginary value (2πf ₀ ) on the imaginary axis as the coupling coefficient (κ) increases. As a result, when the coupling coefficient (κ) is changed, the distance from the driving point to each pole 1 is equal to the distance from the driving point to the zero corresponding to each pole 1, so that the coupling coefficient (κ) The change of the input impedance characteristic (Z _in ) accompanying the change of can be suppressed.

Further, when the equivalent load resistance (R) is increased from near zero, the pole and zero point draw a locus as shown in FIG. 10c. However, the pole 1 shown in FIG. 10c shows a pole (but not including zero) having a value closest to the imaginary axis among the poles of the formula (9), and the zero is the zero of the formula (10). Indicates the zero point closest to the imaginary axis. The dotted arrows indicate the directions of the locus of the pole 1 and zero when the equivalent load resistance (R) is increased discretely. As shown in FIG. 10c, the pole 1 and the zero point draw a symmetrical locus with the dotted line as a boundary while moving away from the imaginary axis as the equivalent load resistance (R) increases. The dotted line indicates a straight line that takes the drive point as an imaginary value, and the drive point (imaginary value of the point) is a value (2πf ₀ ) corresponding to the frequency of the fundamental wave component. That is, the pole 1 and the zero point take a symmetric locus with respect to the imaginary value (2πf ₀ ) on the imaginary axis as the equivalent load resistance (R) increases. Thus, when the equivalent load resistance (R) is changed, the distance from the driving point to each pole 1 becomes equal to the distance from the driving point to the zero corresponding to each pole 1, so that the equivalent load resistance ( The change in the input impedance characteristic (Z _in ) accompanying the change in R) can be suppressed.

Next, a method for setting the absolute value (| Z in _{— s} |) of the input impedance will be described. First, the relationship between the absolute value characteristic of the impedance (Z ₁ ) and the absolute value (| Z in _{— s} |) will be described with reference to FIGS. 11a to 11c. 11a and 11b show the characteristics of impedance (Z ₁ ) with respect to frequency. FIG. 11 c shows the characteristic of the absolute value (| Z in _{— s} |) of the input impedance with respect to the coupling coefficient.

As shown in FIG. 11a, the minimum value maximum value from the frequency _{(f 1)} of the _{(Z MIN)} the frequency band up to a frequency _{(f 2)} of the _{(Z MAX) F 1 (=} f 2 -f 1), FIG. as shown in 11b, when a minimum value maximum value from the frequency _{(f 1)} of the _{(Z MIN)} frequency of _{(Z MAX) (f 2)} frequency band up to _{F 2 (= f 2 -f 1} ), the frequency The band (F ₁ ) is narrower than the frequency band (F ₂ ). Note that the frequency (f ₁ ) and the frequency (f ₂ ) are respectively expressed by Expression (4) and Expression (5). When the frequency band is set to F ₁ and the coupling coefficient (κ) is changed, the absolute value (| Z in _{— s} |) of the input impedance has characteristics as shown in the graph x in FIG. 11c. Further, when the frequency band is set to F ₂ and the coupling coefficient (κ) is changed, the absolute value (| Z in _{— s} |) of the input impedance has characteristics as shown in the graph y of FIG. 11c. That is, if the frequency band between the maximum value frequency and the minimum value frequency of Z _in is narrowed, the absolute value (| Z in _{— s} |) of the input impedance is increased, and if the frequency band is widened, the absolute value of the input impedance is increased. The value (| Z in _{— s} |) is low. Therefore, the present example, in accordance with the frequency band between the frequency of the frequency and the minimum value of the maximum value of Z _in, the input impedance to the frequency (f ₀₎ can be set _(| | Z _{in_s).}

The relationship between the absolute value of input impedance (| Z in _{— s} |) and the impedance of the high-frequency AC power supply unit 6 will be described with reference to FIGS. 12a and 12b. 12a and 12b show the output current-output voltage characteristics of the high-frequency AC power supply unit 6. As an example, FIG. 12a shows the characteristics when the output voltage is constant with respect to the output current, and FIG. The characteristics when the output voltage changes with respect to the output current are shown. The output current-output voltage characteristic of the high-frequency AC power supply unit 6 is determined according to the characteristics of an inverter, a cooler (not shown), etc. included in the high-frequency AC power supply unit 6. Moreover, the curve shown with the dotted line of FIG. 12a and 12b has shown the constant power line, and becomes the same electric power value on the said constant power line.

As shown in FIG. 12a, when the output voltage is constant with respect to the output current, the maximum power that can be supplied by the high-frequency AC power supply unit 6 is the product of the maximum voltage (V _MAX ) and the maximum current (I _MAX ). It is the electric power obtained by. As described with reference to FIG. 6, in order to supply the maximum power from the high frequency AC power supply unit 6, it is necessary to adjust the input impedance of the high frequency AC power supply circuit 6 with respect to the impedance of the AC power supply 601. In the example of FIG. 12a, the impedance (Z _M ) of the high-frequency AC power supply unit 6 is V _MAX / I _MAX from the maximum voltage (V _MAX ) and the maximum current (I _MAX ). The input impedance (| Z in _{— s} |) with respect to the frequency (f ₀ ) of the fundamental wave component of the high-frequency AC power supply circuit 6 is made equal to the impedance (Z _M ) of the high-frequency AC power supply unit 6. The maximum power can be supplied to the non-contact power feeding unit 5.

As shown in FIG. 12b, when the output voltage changes with respect to the output current, the maximum power that can be supplied by the high-frequency AC power supply unit 6 corresponds to the intersection of the highest constant power line and the current-voltage characteristics. Electric power. The impedance (Z _p ) of the high-frequency AC power supply unit 6 is V _p / I _p from the voltage (V _p ) and current (I _p ) corresponding to the intersection. Then, by making the input impedance (| Z in _{— s} |) with respect to the frequency (f ₀ ) of the fundamental wave component of the high-frequency AC power supply circuit 6 equal to the impedance (Z _p ) of the high-frequency AC power supply unit 6, The maximum power can be supplied to the non-contact power feeding unit 5.

That is, in this example, the maximum value frequency and the minimum value frequency of Z _in are set so that the absolute value (| Z in _{— s} |) of the input impedance is equal to the impedance value corresponding to the maximum power of the high-frequency AC power supply unit 6. Set the frequency band between and. Thereby, the power that can be supplied from the high-frequency AC power supply unit 6 can be efficiently supplied to the non-contact power supply unit 5, and the power loss between the high-frequency AC power supply unit 6 and the non-contact power supply unit 5 can be suppressed. it can.

Then, by setting the circuit of the non-contact power feeding unit 5 as described above, the characteristic of the absolute value (| Z in _{— s} |) of the input impedance of the non-contact power feeding unit 5 of this example is shown in FIGS. 13a and 13b. It has the following characteristics. FIG. 13a shows the characteristic of the absolute value (| Z in _{— s} |) of the input impedance with respect to the coupling coefficient (κ), and FIG. 13 b shows the characteristic of the absolute value of the input impedance (| Z in _{— s} |) with respect to the equivalent load resistance (R). . A graph a in FIGS. 13 a and 13 b shows the absolute value (| Z in _{— s} |) of the input impedance, and a graph b shows the absolute value of the impedance of the high-frequency AC power supply unit 6. Note that the impedance of the high-frequency AC power supply unit 6 corresponds to the impedance (Z _M ) in FIG. 12A and the impedance (Z _p ) in FIG. 12B. In FIG. 13a, the coupling coefficient (κ) varies within a range from 0.01 to 0.8, including at least 0.01 to 0.5.

As shown in FIG. 13 a, the absolute value of the input impedance (Z _in ) is substantially constant with respect to the change of the coupling coefficient (κ), and is the same value as the impedance of the high-frequency AC power supply unit 6. That is, even in a situation where the coupling coefficient (κ) changes, the absolute value of the input impedance (Z _in ) with respect to the frequency (f ₀ ) does not change significantly from the absolute value (| Z in _{— s} |) of the input impedance, and the frequency (f the absolute value of the input impedance (Z _in) for ₀₎ to become equal to the absolute value of the impedance of the high frequency AC power supply unit 6, to suppress the loss of the power supplied from the high-frequency AC power source unit 6 to the non-contact power supply unit 5 Can do.

Further, as shown in FIG. 13b, the absolute value of the input impedance (Z _in ) is substantially constant with respect to the change of the equivalent load resistance (R), and is the same value as the impedance of the high-frequency AC power supply unit 6. That is, even in a situation where the equivalent load resistance (R) changes, the absolute value of the input impedance (Z _in ) with respect to the frequency (f ₀ ) does not change greatly from the absolute value of the input impedance (| Z in _{— s} |). Since the absolute value of the input impedance (Z _in ) with respect to f ₀ ) is equal to the absolute value of the impedance of the high-frequency AC power supply unit 6, the loss of power supplied from the high-frequency AC power supply unit 6 to the non-contact power supply unit 5 is suppressed. be able to.

In addition, by setting the circuit of the non-contact power feeding unit 5 as described above, it is possible to prevent a decrease in the power (P _out ) output from the non-contact power feeding unit 5 to the load unit 7 when the coupling coefficient changes. it can. Here, the output power (P _out ) output to the load unit 7 will be described below. In the non-contact power supply device shown in FIG. 1, the output power (P _out ) to the load unit 7 is the supply power (P _out ) supplied from the high-frequency AC power supply unit 6 to the non-contact power supply unit 5 as shown in Expression (10). P _in ) and power lost in the non-contact power feeding unit 5 (P _Loss ).

非接触給電部５において損失される電力（Ｐ_Ｌｏｓｓ）は、供給電力（Ｐ_ｉｎ）に比べて十分小さく、Ｐ_ｉｎ≫Ｐ_Ｌｏｓｓと仮定すると、出力電力（Ｐ_ｏｕｔ）は供給電力（Ｐ_ｉｎ）とほぼ等しいと近似される。また、高周波交流電源部６から非接触給電部５に入力される入力電圧及び入力電流をＶ_ｉｎ及びＩ_ｉｎとすると、供給電力（Ｐ_ｉｎ）は、高周波交流電源部６の出力側からみた非接触給電部５の入力インピーダンス（Ｚ_ｉｎ）と、入力電圧（Ｖ_ｉｎ）と入力電流（Ｉ_ｉｎ）との位相差（θ）により表される。そのため、式（１０）は、式（１１）により近似される。

The power (P _Loss ) lost in the non-contact power supply unit 5 is sufficiently smaller than the supplied power (P _in ), and assuming that P _in >> P _Loss , the output power (P _out ) is the supplied power (P _in ). Is approximately equal. Further, when the input voltage and the input current input from the high-frequency AC power supply unit 6 to the non-contact power supply unit 5 are V _in and I _in , the supplied power (P _in ) is not viewed from the output side of the high-frequency AC power supply unit 6. It is represented by the input impedance (Z _in ) of the contact power supply unit 5 and the phase difference (θ) between the input voltage (V _in ) and the input current (I _in ). Therefore, equation (10) is approximated by equation (11).

すなわち、入力電圧（Ｖ_ｉｎ）を一定として場合には、結合係数の変化に対して、出力電力係数（ｃｏｓθ_ｉｎ／｜Ｚ_ｉｎ｜）を高い値で維持することで、負荷部７への出力電力（Ｐ_ｏｕｔ）を高くすることができる。

That is, when the input voltage (V _in ) is constant, the output power coefficient (cos θ _in / | Z _in |) is maintained at a high value with respect to the change in the coupling coefficient, so that the output to the load unit 7 is maintained. The power (P _out ) can be increased.

The characteristics of the power (P _out ) output to the load unit 7 as the coupling coefficient (κ) changes are described with reference to FIG. FIG. 14A is a graph showing the characteristic of the output power (P _out ) with respect to the coupling coefficient (κ), the graph a is the characteristic when the conventional circuit a is used for the non-contact power feeding unit 5, and the graph b is This is a characteristic when the conventional circuit b is used for the non-contact power feeding unit 5, and a graph c is a characteristic of this example. As shown in FIG. 14a, the non-contact power feeding device of this example takes higher output power than the output power of the conventional circuit a and the conventional circuit b in a wide range of the coupling coefficient with respect to the change of the coupling coefficient (κ). be able to.

Here, when the output power (P _out ) to the load unit 7 is equal to or higher than the threshold power (Pc), the power condition is set assuming that sufficient charging power can be supplied to the battery included in the load 72. To do. FIG. 14 b is a schematic diagram for explaining the range of the coupling coefficient (κ) that satisfies the power condition. In FIG. 14b, a graph a represents a range that satisfies the power condition in the conventional circuit a, a graph b represents a range that satisfies the power condition in the conventional circuit b, and a graph c represents a range that satisfies the power condition in this example. Note that even when power less than the threshold power (Pc) is supplied to the load 72, the battery can be charged. However, since the charging time may be longer, the power condition of this example is less than the threshold power (Pc). The power is the power that does not satisfy the condition.

As shown in FIG. 14b, in this example, the range of the coupling coefficient (κ) that satisfies the power condition is wider than those of the conventional circuit a and the conventional circuit b. In the conventional circuit a and the conventional circuit b, the impedance of the frequency (f ₀ ) changes greatly with respect to the change of the coupling coefficient. When the difference between the impedance value of the frequency (f ₀ ) and the impedance value of the high-frequency AC power supply unit 6 increases, the maximum voltage (rated voltage) or maximum current (rated current) of the high-frequency AC power supply unit 6 is limited. The Therefore, in the conventional circuit a and the conventional circuit b, the range of the coupling coefficient (κ) that satisfies the power condition is narrowed. On the other hand, in this embodiment, the absolute value of the impedance of the frequency _{(f 0)} with respect to the change of the coupling coefficient _{(| Z in_s |)} to suppress a change in the absolute value of the impedance of the frequency _{(f 0) (| Z in_s} | ) Is made equal to the absolute value of the impedance of the high-frequency AC power supply unit 6. Therefore, in this example, the output power (P _out ) can be made larger than in the conventional circuit a and the conventional circuit b, and the range of the coupling coefficient (κ) that satisfies the power condition can be widened.

As described above, in this example, the characteristic of the absolute value of the impedance with respect to the frequency of the impedance (Z ₁ ) is closest to the frequency (f ₀ ) of the fundamental wave component of the high-frequency AC power supply unit 6, and the maximum value (Z _MAX ) the frequency _{(f 2)} to take, closest to the fundamental wave component of the high-frequency AC power source unit 6 frequency _{(f 0),} between the frequency taking the minimum value _{(Z MIN) (f 1)} , the frequency _{(f 0} ), And the characteristic of the absolute value of the impedance with respect to the frequency of the impedance (Z ₂ ) has a maximum value in the vicinity of the frequency (f ₀ ). Thereby, when the coupling coefficient changes, it is possible to suppress a change _in the input impedance (Z _in ) viewed from the high-frequency AC power supply unit 6 side, so that the power supplied from the high-frequency AC power supply unit 6 to the non-contact power supply unit 5 Can prevent loss. Further, in this example, even if a relative displacement between the primary winding 101 and the secondary winding 201 occurs and the coupling coefficient changes, loss of power supplied to the non-contact power feeding unit 5 can be prevented. Therefore, the power transmission distance corresponding to the distance between the primary winding 101 and the secondary winding 201 can be extended.

Further, in this example, the electric capacity (C _1s ), the electric capacity (C _1p ), the inductance (L ₁ ), the inductance (L ₂ ), and the electric capacity (C _2p ) are satisfied so as to satisfy the expressions (3) and (7). ) Is set. Thereby, when the coupling coefficient changes, it is possible to suppress a change _in the input impedance (Z _in ) viewed from the high-frequency AC power supply unit 6 side, so that the power supplied from the high-frequency AC power supply unit 6 to the non-contact power supply unit 5 Can prevent loss. Further, in this example, even if a relative displacement between the primary winding 101 and the secondary winding 201 occurs and the coupling coefficient changes, loss of power supplied to the non-contact power feeding unit 5 can be prevented. Therefore, the power transmission distance corresponding to the distance between the primary winding 101 and the secondary winding 201 can be extended.

The present embodiment, the absolute value of the input impedance with respect to the frequency of the fundamental wave component of the high-frequency AC power source unit _{6 (f 0) (| Z} in_s |) is set according to the value of the impedance of the high frequency AC power supply unit 6. Thus, the absolute value of the input impedance with respect to the frequency _{(f 0) (| Z in_s} |) it is possible to be equal to the value of the impedance of the high frequency AC power supply unit 6, also the coupling coefficient is changed, the high-frequency AC power supply unit 6 can be supplied to the non-contact power supply unit 5.

Further, in this example, when the coupling coefficient between the primary winding 101 and the secondary winding 201 changes within a range of 0.01 to 0.5, the absolute value of the input impedance with respect to the frequency (f ₀ ) ( | Z in _{— s} |) changes in the vicinity of the impedance value of the high-frequency AC power supply unit 6. Thereby, even if a coupling coefficient changes by this example, the maximum electric power which the high frequency alternating current power supply part 6 can output can be supplied to the non-contact electric power feeding part 5. FIG.

Further, in this example, when the characteristics of the input impedance (Z _in ) of the non-contact power feeding unit 5 viewed from the high frequency AC power supply unit 6 side are shown in a complex plane, the pole and zero closest to the imaginary axis are on the imaginary axis, A locus symmetric with respect to a value (2πf ₀ ) corresponding to the frequency (f ₀ ) is taken. Thus, in the case of varying the coupling coefficient (kappa), the imaginary value of the imaginary axis distance from the point indicating the (2 [pi] f ₀₎ to pole, the imaginary value of the imaginary axis zero point from the point indicating the (2 [pi] f ₀₎ Therefore, the change in the input impedance characteristic (Z _in ) accompanying the change in the coupling coefficient (κ) can be suppressed. As a result, the high-frequency AC power supply unit 6 supplies the contactless power supply unit 5 to the contactless power supply unit 5. It is possible to prevent loss of electric power.

In this example, the frequency difference between the frequency (f ₁ ) and the frequency (f ₂ ) represented by the equations (4) and (5) is set according to the impedance of the high-frequency AC power supply unit 6. That is, the absolute value of the input impedance with respect to the frequency _{(f 0) (| Z in_s} |) as is equal to the impedance of the high frequency AC power supply unit 6, the frequency and _{(f 1)} the difference in frequency between the frequency _{(f 2)} Therefore, even if the coupling coefficient changes, the maximum power that can be output from the high-frequency AC power supply unit 6 can be supplied to the non-contact power supply unit 5.

Note that the absolute value (| Z in _{— s} |) of the input impedance is not necessarily equal to the fixed value with respect to the change of the coupling coefficient (κ), and may be changed within a predetermined range including the fixed value. . That is, as shown in FIG. 9, when the characteristic of the absolute value of the impedance is shown with respect to the change of the coupling coefficient (κ), the frequency (in comparison with other frequency bands other than the frequency (f ₀ ) It is only necessary to suppress the change in the absolute value of the impedance at f ₀ ).

The absolute value of the input impedance to the frequency _{(f 0) (| Z in_s} |) in all the range of the coupling coefficient varying need not be equal to the value of the impedance of the high frequency AC power supply unit 6, in Figure 13a As shown, it is only necessary to show such a characteristic that the absolute value (Z in _{— s} ) of the input impedance is close to the impedance value of the high-frequency AC power supply unit 6 within the range of the coupling coefficient to be changed.

  Note that the capacitor 102 of this example corresponds to the “first capacitor” of the present invention, the capacitor 103 is the “second capacitor” of the present invention, the capacitor 202 is the “third capacitor” of the present invention, The contact power supply unit 4 corresponds to a “power supply circuit”, and the high-frequency AC power supply unit 6 corresponds to an “AC power supply”.

<< Second Embodiment >>
FIG. 15 is a circuit diagram of a power feeding circuit unit 5 of a contactless power feeding device according to another embodiment of the invention. In this example, the position to which the capacitor 102 is connected on the power transmission circuit of the power feeding circuit unit 5 is different from the first embodiment described above. Since the other configuration is the same as that of the first embodiment described above, the description thereof is incorporated.

  As illustrated in FIG. 15, the power feeding circuit unit 5 includes, as a power transmission circuit, a primary winding 101, a capacitor 102 connected in series to the primary winding 101, and a capacitor 103 connected in parallel to the primary winding 101. The capacitor 102 is connected between the capacitor 103 and the primary winding 101. The power feeding circuit unit 5 includes a secondary winding 201 and a capacitor 202 connected in parallel to the secondary winding 201 as a power receiving circuit.

Next, in the circuit shown in FIG. 15, the impedance (Z ₁ ) on the primary side as viewed from the high-frequency AC power supply 6 side (power transmission side) is described with reference to FIG. FIG. 16 shows a characteristic of an absolute value of impedance (Z ₁ ) with respect to frequency.

The characteristic of the impedance (Z ₁ ) according to the first embodiment takes a minimum value (Z _MIN ) for a low frequency (f ₁ ) and a maximum for a high frequency (f ₂ ), as shown in FIG. 8a. Takes the value (Z _MAX ). On the other hand, as shown in FIG. 16, the impedance (Z ₁ ) characteristic of this example takes a maximum value (Z _MAX ) for a low frequency (f ₁ ) and a minimum value for a high frequency (f ₂ ). Take (Z _MIN ).

The characteristic of the absolute value of the impedance (Z ₁ ) is a high-frequency AC power supply between a frequency (f ₁ ) that takes a maximum value (Z _MAX ) and a frequency (f ₂ ) that takes a minimum value (Z _MIN ). It has the frequency (f ₀ ) of the fundamental wave component of the circuit 6.

As described above, the power transmission side of the contactless power supply unit 5 of the present example may connect one end of the capacitor 103 to the connection point between the capacitor 102 and the primary winding 101 as shown in the first embodiment. As shown in the second embodiment, a capacitor 102 may be connected between the capacitor 103 and the primary winding 101. Accordingly, in this example, when the coupling coefficient changes, the change in input impedance (Z _in ) viewed from the high-frequency AC power supply unit 6 side can be suppressed, so that the high-frequency AC power supply unit 6 transfers to the non-contact power supply unit 5. Loss of power to be supplied can be prevented. Further, in this example, even if a relative displacement between the primary winding 101 and the secondary winding 201 occurs and the coupling coefficient changes, loss of power supplied to the non-contact power feeding unit 5 can be prevented. Therefore, the power transmission distance corresponding to the distance between the primary winding 101 and the secondary winding 201 can be extended.

<< Third Embodiment >>
FIG. 17 is a circuit diagram of the power feeding circuit unit 5 of the non-contact power feeding device according to another embodiment of the invention. In this example, the point which has the coil 104 in the power transmission circuit of the electric power feeding circuit part 5 differs with respect to 1st Embodiment mentioned above. Since the other configuration is the same as that of the first embodiment described above, the description thereof is incorporated.

  As shown in FIG. 17, the power feeding circuit unit 5 includes, as a power transmission circuit, a primary winding 101, a capacitor 102 connected in series to the primary winding 101, and a capacitor 103 connected in parallel to the primary winding 101. , The connecting point between the primary winding 101 and the capacitor 103 is connected to one end of the capacitor 102, and the coil 104 is connected to the other end of the capacitor 102. The coil 104 is inserted as a choke coil for suppressing harmonics of the output of the high-frequency AC power supply unit 6, or is inserted for short circuit prevention or the like.

Next, in the circuit shown in FIG. 17, the impedance (Z ₁ ) on the primary side as viewed from the high frequency AC power supply 6 side (power transmission side) is described with reference to FIG. FIG. 18 shows a characteristic of an absolute value of impedance (Z ₁ ) with respect to frequency. In this example, since the coil 104 is connected to the non-contact power supply unit 5, a resonance system composed of L ₁ and C _1s + C _1p + L _1s is formed. _Therefore , the non-contact power supply unit 5 of the first embodiment is resonant. The frequency (f ₄ ) increases by one. As shown in FIG. 18, the characteristic of the absolute value of the impedance (Z ₁ ) is between the frequency (f ₁ ) that takes the minimum value (Z _{MIN — 1} ) and the frequency (f ₂ ) that takes the maximum value (Z _MAX ). And the frequency (f ₀ ) of the fundamental wave component of the high-frequency AC power supply circuit 6. The frequency (f ₁ ) is a frequency with respect to the minimum value closest to the frequency (f ₀ ) among the resonance frequencies of the impedance (Z ₁ ), and the frequency (f ₂ ) is the frequency of the resonance frequency of the impedance (Z ₁ ). , The frequency with respect to the maximum value closest to the frequency (f ₀ ). The characteristic of the absolute value of the impedance (Z ₁ ) has a resonance frequency (f ₄ ) having a minimum value (Z _{MIN — 2} ) in a band other than the frequency band from the frequency (f ₁ ) to the frequency (f ₂ ). In other words, the characteristic of the absolute value of the impedance (Z ₁ ) is a resonance having a frequency (f ₀ ) in the frequency band from the frequency (f ₁ ) to the frequency (f ₂ ) and having a minimum value (Z _{MIN — 2} ). Does not have a frequency (f ₄ ).

As described above, the coil 104 may be connected to the capacitor 102 on the power transmission side of the non-contact power feeding unit 5 of this example, and at least the characteristic of the absolute value of the impedance (Z ₁ ) is the minimum value (Z _{MIN — 1} ). The frequency (f ₀ ) of the fundamental wave component of the high-frequency AC power supply circuit 6 may be between the frequency (f ₁ ) taking the maximum value (Z ₁ ) and the frequency (f ₂ ) taking the maximum value (Z _MAX ). Accordingly, in this example, when the coupling coefficient changes, the change in input impedance (Z _in ) viewed from the high-frequency AC power supply unit 6 side can be suppressed, so that the high-frequency AC power supply unit 6 transfers to the non-contact power supply unit 5. Loss of power to be supplied can be prevented. Further, in this example, even if a relative displacement between the primary winding 101 and the secondary winding 201 occurs and the coupling coefficient changes, loss of power supplied to the non-contact power feeding unit 5 can be prevented. Therefore, the power transmission distance corresponding to the distance between the primary winding 101 and the secondary winding 201 can be extended.

In this example, a circuit element other than the coil 104 may be connected to the power transmission side of the non-contact power feeding unit 5 or a plurality of circuit elements may be connected, and at least the impedance (Z ₁ ) is absolute. Between the frequency (f ₁ ) where the characteristic of the value takes the minimum value (Z _{MIN — 1} ) and the frequency (f ₂ ) where the maximum value (Z _MAX ) takes, the frequency of the fundamental wave component ( f ₀ ).

In this example, another circuit element may be connected to the circuit shown in FIG. 15 on the power transmission side of the non-contact power feeding unit 5, and at least the absolute value characteristic of the impedance (Z ₁ ) is minimal. Between the frequency (f ₁ ) taking the value (Z _{MIN — 1} ) and the frequency (f ₂ ) taking the maximum value (Z _MAX ), the frequency (f ₀ ) of the fundamental wave component of the high-frequency AC power supply circuit 6 is included. That's fine.

In this example, another circuit element may be connected to the power receiving side of the non-contact power feeding unit 5, and at least the characteristic of the absolute value of impedance (Z ₂ ) is the fundamental wave component of the high-frequency AC power supply circuit 6. or if it has a maximum value _{(Z MAX)} in the vicinity of the frequency _{(f 0).}

6 ... High-frequency AC power supply 61 ... Rectifier 61a-61f ... Diode 62 ... Smoothing capacitor 63 ... Voltage type inverter 63a-63d ... Transistor 64 ... Three-phase AC power supply 7 ... Load part 71 ... Rectifier 71a-71d ... Diode 72 ... Load 5 ... Non-contact power feeding part 3 ... Power transmission circuit part 101 ... Primary winding 102, 103 ... Capacitor 104 ... Coil 4 ... Power receiving circuit part 201 ... Secondary winding 202 ... Capacitor 701 ... Equivalent load resistance

Claims (6)

It has a secondary winding that is supplied with power from the primary winding by an AC power source,
The characteristic of the absolute value of the impedance with respect to the frequency of Z1 is between the frequency that is closest to the frequency of the fundamental wave component of the AC power supply and has a maximum value, and the frequency that is closest to the frequency of the fundamental wave component and has a minimum value. Having the frequency of the fundamental component,
The contactless power feeding device according to claim 1, wherein the characteristic of the absolute value of the impedance with respect to the frequency of Z2 has a maximum value in the vicinity of the frequency of the fundamental wave component.
However,
Z1 represents the impedance of only the primary side viewed from the output side of the AC power supply,
Z2 indicates the impedance of only the secondary side viewed from the load side connected to the secondary winding. A first capacitor connected in series to the primary winding, a second capacitor connected in parallel to the primary winding, and a third capacitor connected in parallel to the secondary winding;
_{C 1p <(L 2 / L} 1) C 2p <(C 1s + C 1p) and _{C 2p = 1 / (L 2} (2πf 0) ^ 2) non-contact power supply of claim 1, wherein a satisfying apparatus.
However,
C _1s indicates the electric capacity of the first capacitor;
C _1p represents the capacitance of the second capacitor,
L ₁ represents the inductance of the primary winding,
C _2p represents the capacitance of the third capacitor,
f ₀ represents the frequency of the fundamental wave component of the AC power supply,
L ₂ represents the inductance of the secondary winding. 3. The contactless power supply device according to claim 1, wherein an absolute value of Z _in with respect to a frequency of the fundamental wave component is set according to an impedance value of the AC power supply.
However,
Z _in represents the input impedance of the power feeding circuit including the primary winding and the secondary winding, as viewed from the output side of the AC power supply. When the coupling coefficient between the primary winding and the secondary winding changes within a range of 0.01 to 0.5, the absolute value of Z _in with respect to the frequency of the fundamental component is the AC The contactless power feeding device according to claim 1, wherein the contactless power feeding device changes in the vicinity of the impedance value of the power source.
However,
Z _in represents the input impedance of the power feeding circuit including the primary winding and the secondary winding, as viewed from the output side of the AC power supply. A first capacitor connected in series to the primary winding, a second capacitor connected in parallel to the primary winding, and a third capacitor connected in parallel to the secondary winding;
When the characteristics of the input impedance of the feeder circuit including the primary winding and the secondary winding as seen from the output side of the AC power source are shown in a complex plane,
The poles and zeros closest to the imaginary axis are values corresponding to the frequency (f ₀ ) of the fundamental wave component on the imaginary axis as the coupling coefficient between the primary winding and the secondary winding increases. The non-contact power feeding device according to claim 1, wherein the trajectory is symmetrical with respect to 2πf ₀ ). A first capacitor connected in series to the primary winding, a second capacitor connected in parallel to the primary winding, and a third capacitor connected in parallel to the secondary winding;
a frequency difference between f ₁ and f ₂ is the non-contact power feeding device according to any one of claims 1 to 5, characterized in that it is set in accordance with the impedance of the AC power supply.
However,

C _1s indicates the electric capacity of the first capacitor;
C _1p represents the capacitance of the second capacitor,
L ₁ represents the inductance of the primary winding,
f ₀ represents the frequency of the fundamental wave component of the AC power supply.

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