JP2013121230A - Non-contact power transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power transmission system which is capable of supplying only necessary power to the power receiving side with a simple configuration.SOLUTION: The non-contact power transmission system comprises: a power supply device which is provided with an AC constant-voltage power supply unit; a power supply-side resonance capacitor; a power supply antenna coil; and a power receiving device which is provided with a power receiving antenna coil and a load and is movable relative to the power supply device. The power receiving device supplies the load with power transmitted from the power supply antenna coil to the power receiving antenna coil. The power supply-side resonance capacitor and the power supply antenna coil are connected in parallel to the AC constant-voltage power supply unit.

Description

  The present invention relates to a non-contact power transmission system that supplies electric power in a non-contact manner from a power feeding side to a power receiving side by electromagnetic waves.

  Patent Document 1 discloses a configuration in which a power transmission coil and a resonance capacitor of a power transmission side unit are connected in series, and a resonance capacitor of a power reception side unit is connected in parallel to the power reception coil. In addition, a Hall element is further arranged in the vicinity of the power transmission coil of the power transmission side unit, and the power is transmitted from the power transmission coil to the power reception coil when a magnetic flux is detected by a permanent magnet disposed in the vicinity of the power reception coil of the power reception side unit. Is also disclosed.

  On the other hand, in Patent Document 2, the resonance circuit of the input / output device including the inductance and the capacitor is electromagnetically coupled to the resonance circuit of the main body side, and power is supplied from the main body side resonance circuit to the resonance circuit of the input / output device by electromagnetic induction. The structure to be disclosed is disclosed.

  The values of the inductance and capacitance of the resonance circuit are set to values at which resonance occurs in the resonance circuit in accordance with the frequency of the current that the communication circuit of the device body passes through the inductance of the main body side resonance circuit. There is also a description that the resonance circuit may have a series resonance circuit configuration in which an inductance and a capacitor are connected in series.

JP 2011-130369 A JP 2011-130474 A

  In the configuration of Patent Document 1, even when the power receiving side unit does not require power, if the power transmitting coil and the power receiving coil are opposed to each other, power is supplied, and the power transmitting coil of the power transmitting side unit and the resonance capacitor are connected in series. Since the connected portion has low impedance, there is a problem that wasteful power is consumed.

  Further, even in the configuration of Patent Document 2, there is a problem that power is supplied even when the input / output device side to which power is supplied does not require power, and wasteful power is consumed on the main body side.

  Accordingly, an object of the present invention is to provide a power transmission system that can supply only necessary power to the power receiving side with a simple configuration.

  The present invention includes the above-described problem, including a power supply device including an AC constant voltage power supply unit, a power supply side resonance capacitor, and a power supply antenna coil, a power reception antenna coil, and a load, and moves relative to the power supply device. The power receiving device supplies the power transmitted from the power feeding antenna coil to the power receiving antenna coil to the load, and the power transmission side resonance capacitor and the power transmitting antenna coil are parallel to the AC constant voltage power supply unit. It is solved by a non-contact power transmission system connected to.

  The power receiving apparatus may further include a power receiving side matching capacitor, one end of the power receiving antenna coil may be connected to the load via the power receiving side matching capacitor, and the other end of the power receiving antenna coil may be directly connected to the load.

  The power receiving apparatus further includes a power receiving side boost capacitor, one end of the power receiving side boost capacitor is connected between the power receiving antenna coil and the power receiving side matching capacitor, and the other end of the power receiving side boost capacitor is between the power receiving antenna coil and the load. It may be connected.

  Further, a plurality of power supply antenna coils may be provided, and all of them may be connected in parallel with the power supply side resonance capacitor.

  According to the present invention, it is possible to provide a power transmission system that supplies only necessary power to the power receiving side with a simple configuration.

It is a circuit block diagram showing an example of an embodiment of the present invention. It is a circuit block diagram showing an example of an embodiment of the present invention. It is a circuit block diagram showing an example of an embodiment of the present invention. It is a circuit block diagram showing an example of an embodiment of the present invention. It is a circuit block diagram showing an example of an embodiment of the present invention. It is a graph which shows the power transmission efficiency with respect to the impedance of a pseudo load. It is a graph which shows the power transmission efficiency with respect to the frequency of transmission power. It is a graph which shows the relationship between antenna area ratio and electric power transmission efficiency.

(Embodiment 1)
The present invention includes, for example, a power supply device including an AC constant voltage power supply unit, a power supply side resonance capacitor, and a power supply antenna coil, a power reception antenna coil, and a load, and can move relative to the power supply device. The power receiving device supplies the power transmitted from the power feeding antenna coil to the power receiving antenna coil to the load, and the power transmission side resonance capacitor and the power transmission antenna coil are connected in parallel to the AC constant voltage power supply unit. Embodiments of connected contactless power transfer systems can be taken.

  Here, the AC constant voltage power supply unit has a function of providing an AC voltage having a constant voltage amplitude regardless of the impedance fluctuation of the load. Even if the voltage amplitude fluctuates due to the impedance fluctuation of the load, the load Any power source or circuit having a design philosophy that suppresses fluctuations in voltage amplitude with respect to impedance fluctuations is included.

  When a parallel resonant circuit is configured by the power supply side resonance capacitor and the power supply antenna coil, and AC constant voltage power with a frequency close to the resonance point of the parallel resonant circuit is supplied to the parallel resonant circuit, the parallel resonant circuit becomes high impedance. Power consumption in the circuit is minimized.

  Hereinafter, such a state in which the parallel resonant circuit has a high impedance is referred to as a standby state. In the standby state, a certain electromagnetic field energy is stored in the vicinity of the feeding antenna coil.

  When the power feeding antenna coil of the power feeding device and the power receiving antenna coil of the power receiving device are close to each other and face each other, when the load impedance of the power receiving device is low, the energy of the electromagnetic field stored near the power feeding antenna coil is transmitted to the power receiving antenna coil. Then, power transmission from the feeding antenna coil to the receiving antenna coil occurs.

  At this time, the parallel resonance circuit on the power feeding device side is out of the resonance point due to the mutual inductance with the power receiving antenna coil, and the impedance is lowered. A state where such a parallel resonant circuit has a low impedance is called a power transmission state.

  In such a power transmission state, power consumption occurs in the parallel resonance circuit on the power feeding apparatus side, but the consumed power is directly transmitted to the power receiving apparatus via the power receiving antenna coil.

  As described above, when it is not necessary to supply power to the power receiving apparatus, the power feeding apparatus is in a standby state. When it is necessary to supply power to the power receiving apparatus, the power feeding apparatus shifts to a power transmission state.

  That is, a complicated mechanism such as a magnetic switch using a Hall element and a permanent magnet described in Patent Document 1 is not required, and only power necessary for the power receiving device can be supplied from the power feeding device. A highly efficient contactless power transmission system can be obtained.

  Note that when the load of the power receiving device is a secondary battery via a rectifier circuit, for example, and the secondary battery is in a fully charged state, the impedance of the load becomes high.

  Furthermore, even if the feeding antenna coil and the receiving antenna coil are close to each other and facing each other, since the impedance of the load is high, the impedance of the receiving antenna coil is also high, and the impedance of the parallel resonance circuit in the feeding device is not reduced, Power transmission to the power receiving device hardly occurs.

  That is, even if the power feeding antenna coil and the power receiving antenna coil are close to each other and face each other, useless power transmission does not occur unless the power receiving apparatus requires power.

  In addition, when the power feeding antenna coil and the power receiving antenna coil are slightly separated from each other, or when the center positions of the coils are slightly shifted from each other, the amount of power that can be transmitted from the power feeding device to the power receiving device is reduced.

  In this case, since the impedance of the parallel resonance circuit of the power feeding device does not decrease much as in the power transmission state, the amount of transmission power supplied from the power feeding device to the power receiving device can be suppressed. Therefore, in this case, power transmission is not wasted.

  That is, by adopting this embodiment, even if the feeding antenna coil and the receiving antenna coil are slightly separated from each other or the center positions of the coils are slightly shifted from each other, the sizes of the feeding antenna coil and the receiving antenna coil And the same power transmission efficiency as when the center positions match each other can be maintained.

  A specific example of this embodiment will be described with reference to the drawings.

  FIG. 1 is a circuit block diagram showing an example of an embodiment of the present invention. The AC constant voltage power supply unit 10 includes a power supply side resonance capacitor 11 and a power supply antenna coil 12 connected in parallel to form a power supply device. The power reception antenna coil 20 is connected to a rectifier circuit 211, and the rectifier circuit 211 is connected to the secondary battery 212. Connected to form a power receiving device.

  The rectifier circuit 211 and the secondary battery 212 are loads on the power receiving antenna coil 20.

  Further, the secondary battery 212 may be an electronic circuit that is driven by a DC voltage. Furthermore, as long as it is a load such as an electric motor driven by an AC voltage or an ultrasonic vibrator, the load may be directly connected to the power receiving antenna coil 20 without using the rectifier circuit 211.

  FIG. 2 is a circuit block diagram showing an example of the embodiment of the present invention. FIG. 2 shows a configuration in which a power reception side resonance capacitor 22 is connected in parallel to the power reception antenna coil 20 in the configuration of FIG. 1, and the power reception side resonance capacitor 22 is connected to the rectifier circuit 211.

  The rectifier circuit 211 is obtained by combining the resonance point of the parallel resonance circuit including the power supply side resonance capacitor 11 and the power supply antenna coil 12 in the power supply device with the resonance point of the parallel resonance circuit including the power reception antenna coil 20 and the power reception side resonance capacitor 22 in the power reception device. It is possible to supply power with high efficiency.

  Since the electromagnetic field induced in the feeding antenna coil 12 is controlled by the AC constant voltage power supply unit 10, an excessive voltage is induced in the parallel resonant circuit including the power receiving antenna coil 20 and the power receiving side resonance capacitor 22. Can be prevented.

(Embodiment 2)
In addition to the first embodiment, the power receiving device further includes a power receiving side matching capacitor, and one end of the power receiving antenna coil is connected to the load via the power receiving side matching capacitor, and the other end of the power receiving antenna coil is connected to the load. Directly connected embodiments are possible.

  By adjusting the reactance of the power-receiving-side matching capacitor, the combined impedance of the power-receiving antenna coil, the power-receiving-side matching capacitor, and the load can be minimized, thereby increasing the amount of power transmitted from the power feeding device to the power receiving device. be able to.

  In addition, since the absolute value of the reactance component in the combined impedance of the power receiving antenna coil and the power receiving side and the load can be minimized, preferably zero, power reflection from the power receiving antenna coil to the power feeding antenna coil is minimized, The power transmission efficiency can be further improved.

  A specific example of this embodiment will be described with reference to the drawings.

  FIG. 3 is a circuit block diagram showing an example of the embodiment of the present invention. FIG. 3 shows a configuration in which a power receiving side matching capacitor 23 is connected between one end of the power receiving antenna coil 20 and the rectifier circuit 211 in the configuration of FIG.

(Embodiment 3)
In addition to the second embodiment, the power receiving device further includes a power receiving side boost capacitor, and one end of the power receiving side boost capacitor is connected between the power receiving antenna coil and the power receiving side matching capacitor. Embodiments in which the end is connected between the power receiving antenna coil and the load can be taken.

  If the receiving side step-up capacitor is connected in parallel with the receiving antenna coil and the resonance point is brought close to the frequency of the AC magnetic field generated from the feeding antenna coil, the amplitude of the AC voltage supplied to the load is increased and the distance from the resonance point is increased. Thus, the AC voltage amplitude supplied to the load can be reduced.

  Therefore, for example, when the load is an electronic circuit, by adjusting the impedance of the power receiving side step-up capacitor, it is possible to supply power having an optimal AC voltage amplitude to the electronic circuit as a load for driving.

  Further, for example, even when the load is a secondary battery via a rectifier circuit, a voltage sufficient to charge the secondary battery is ensured by adjusting the voltage amplitude applied to the rectifier circuit by the power receiving side boost capacitor. be able to.

  That is, it is possible to adjust the AC current amplitude applied to the load by the power receiving side series resonance capacitor in the second embodiment, and the AC voltage amplitude applied to the load by the power receiving side boost capacitor in the present embodiment.

  A specific example of this embodiment will be described with reference to the drawings.

  FIG. 4 is a circuit block diagram showing an example of the embodiment of the present invention. 4, one end of the power receiving side boost capacitor 24 is connected between one end of the power receiving antenna coil 20 and the power receiving side matching capacitor 23 in the configuration of FIG. 3, and power is received between the other end of the power receiving antenna coil 20 and the rectifier circuit 211. The other end of the side boost capacitor 24 is connected.

(Embodiment 4)
In addition to the first embodiment, the present invention may further include an embodiment in which a plurality of feeding antenna coils are provided and all are connected in parallel with the feeding-side resonance capacitor.

  According to the first embodiment, even if the feeding antenna coil and the receiving antenna coil are slightly separated from each other or the center positions of the coils are slightly shifted from each other, the sizes of the feeding antenna coil and the receiving antenna coil are equal, However, in this embodiment, by providing a plurality of feeding antenna coils, an area where power can be transmitted to the power receiving apparatus is expanded.

  In this embodiment, it is desirable that the mutual inductance, that is, the coupling coefficient, of the feeding antenna coils adjacent to each other be a minimum value.

  If the coupling coefficient of adjacent feeding antenna coils is zero, the electromagnetic fields generated by the respective feeding antenna coils do not cancel each other, so that the area of the electromagnetic field generated by the plurality of feeding antenna coils can be maximized. .

  Adjustment to make the coupling coefficient between adjacent feeding antenna coils to be zero can be made by short-circuiting both ends of one feeding antenna coil and finding the distance between the feeding antenna coil centers where the inductance of the other feeding antenna coil is maximum. good.

  A specific example of this embodiment will be described with reference to the drawings.

  FIG. 5 is a circuit block diagram showing an example of the embodiment of the present invention. FIG. 5 shows a configuration in which the power supply side resonance capacitor 11 and the power supply antenna coils 12 and 121 in the configuration of FIG. 1 are connected in parallel.

  Examples of the present invention will be described.

Example 1
In this example, the circuit configuration shown in FIG. 3 in the second embodiment was used, and each component was configured as follows.

  An AC voltage having a constant voltage amplitude of 13.56 MHz is supplied from the AC constant voltage power supply unit 10.

  The feeding antenna coil 12 is a pattern coil having a diameter of 30 mm, a width of 1.5 mm and a distance of 1.0 mm formed on a double-sided flexible substrate, and a soft coil having an outer diameter of 30 mm and a thickness of 0.2 mm attached to the pattern coil. It comprised with the soft-magnetic sheet | seat which is a sheet | seat comprised with the magnetic powder and the binder.

  The power supply side resonance capacitor 11 was adjusted so that the resonance point coincided with the frequency 13.56 MHz of the AC voltage supplied from the AC constant voltage power supply unit 10.

  The power receiving antenna coil 20 has a pattern coil having an outer diameter of 20 mm, a width of 1.5 mm and a distance of 1.0 mm formed on a double-sided flexible substrate, and a soft magnetism having a diameter of 20 mm and a thickness of 0.2 mm attached to the pattern coil. A sheet was used.

  Note that the soft magnetic sheet was disposed on the back side of the surface on which the feeding antenna coil 12 and the power receiving antenna coil 20 face each other.

  The power receiving side matching capacitor 23 was adjusted so that the series resonance frequency with the power receiving antenna coil 20 was 11.86 MHz.

  The rectifier circuit 211 is a diode bridge circuit.

  The secondary battery 212 was replaced with a pseudo load having an impedance of 10Ω.

  When the power supply antenna coil 12 and the power receiving antenna coil 20 are charged and separated with the above configuration, the impedance of the resonance circuit by the power supply antenna coil 12 and the power supply side resonance capacitor 11 is 1 kΩ, and is determined by the resonance circuit on the power supply device side. Power consumption was suppressed.

  When the power feeding antenna coil 12 and the power receiving antenna coil 20 are close to each other and face each other, the impedance of the resonance circuit formed by the power feeding antenna coil 12 and the power feeding side resonance capacitor 11 becomes 11Ω, and the power from the power feeding device to the power receiving device is 2.7 W. Could be transmitted.

  At this time, the power transmission efficiency, which is the ratio of the power received by the power receiving device to the power consumed on the power feeding device side, was 90%.

  When an IC card with a built-in loop antenna is placed close to and opposed to the feeding antenna coil 12, the impedance of the resonance circuit by the feeding antenna coil 12 and the feeding-side resonance capacitor 11 becomes 700Ω, and the feeding device to the IC card. The transmitted power was 29 mW, and no excessive power was supplied.

(Example 2)
In this example, the circuit configuration of FIG.

  The AC constant voltage power supply unit 10, the power supply side resonance capacitor 11, the power supply antenna coil 12, the power reception antenna coil 20, and the rectifier circuit 211 have the same configuration as in the first embodiment.

  In this embodiment, the power receiving side matching capacitor 23 and the power receiving side step-up capacitor 24 are adjusted so that the power transmission efficiency is maximized.

  FIG. 6 is a graph showing the power transmission efficiency with respect to the impedance of the pseudo load. FIG. 6 shows the power transmission efficiency in the configuration of this example and the power transmission efficiency in the comparative example configuration in which the power supply side resonance capacitor 11 is removed from this example.

  In particular, when the pseudo load is in the range of 10Ω to 30Ω, this example maintains the power transmission efficiency, while the comparative example shows that the power transmission efficiency is greatly reduced.

  FIG. 7 is a graph showing the power transmission efficiency with respect to the frequency of the power supplied from the AC constant voltage power supply unit when the pseudo load is 10Ω, that is, the frequency of the transmission power.

  The configuration of the comparative example is the same as that shown in FIG. From FIG. 7, at a frequency of 5 MHz or higher, the power transmission efficiency of this example is as high as 90%, whereas the power transmission efficiency of the comparative example is only 80%.

  FIG. 8 is a graph showing the relationship between the antenna area ratio, which is the area ratio of the power receiving antenna coil 20 to the power feeding antenna coil 12, and the power transmission efficiency when the pseudo load is 10Ω. The configuration of the comparative example is the same as that shown in FIG.

  FIG. 8 shows that the power transmission efficiency is maintained even when the antenna area ratio is 0.2 to 0.7 in the present embodiment, whereas the power transmission efficiency is greatly reduced in the comparative example.

DESCRIPTION OF SYMBOLS 10 AC constant voltage electric power supply part 11 Power supply side resonance capacitor 12, 121 Power supply antenna coil 20 Power reception antenna coil 22 Power reception side resonance capacitor 23 Power reception side matching capacitor 24 Power reception side boost capacitor 211 Rectifier circuit 212 Secondary battery

Claims (4)

AC constant voltage power supply unit,
Resonant capacitor on the power supply side,
And a power feeding device including a power feeding antenna coil,
Power receiving antenna coil,
And with load,
A power receiving device capable of moving relative to the power supply device;
The power receiving device supplies the power transmitted from the power feeding antenna coil to the power receiving antenna coil to the load;
The contactless power transmission system, wherein the power transmission side resonance capacitor and the power transmission antenna coil are connected in parallel to the AC constant voltage power supply unit. The power receiving device is:
In addition, a receiving side matching capacitor is provided,
One end of the power receiving antenna coil is connected to the load via the power receiving side matching capacitor,
The contactless power transmission system according to claim 1, wherein the other end of the power receiving antenna coil is directly connected to the load. The power receiving device further includes a power receiving side step-up capacitor,
One end of the power receiving side boost capacitor is connected between the power receiving antenna coil and the power receiving side matching capacitor,
The contactless power transmission system according to claim 2, wherein the other end of the power receiving side step-up capacitor is connected between the power receiving antenna coil and the load. 4. The non-contact power transmission system according to claim 1, wherein a plurality of the feeding antenna coils are provided, and all of the feeding antenna coils are connected in parallel with the feeding-side resonance capacitor.

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