JP7087941B2 - Energy harvesting equipment - Google Patents

Description

The present invention relates to an energy harvesting device that recovers electromagnetic energy in the environment and uses it as electric power.

"Energy harvesting" is also called energy harvesting, and one of them is a technology that recovers and uses weak electric power from electromagnetic wave energy that is thin and widely present in the environment. An energy harvesting device that performs such energy harvesting is an independent power supply separated from the grid power supply, but does not require regular battery replacement like a primary battery, so it can be applied as a high-value-added power supply device. Is expected.

As an example of an environmental power generation device, Patent Document 1 includes a first antenna element that receives electromagnetic waves of horizontally polarized waves and a second antenna element that receives electromagnetic waves of vertically polarized waves, and receives electromagnetic waves of different polarizations. A device for recovering energy is shown. Further, Patent Document 1 includes an antenna corresponding to the frequency of electromagnetic waves transmitted by horizontally polarized waves and an antenna corresponding to the frequency of electromagnetic waves transmitted by vertically polarized waves, and recovers the energy of each electromagnetic wave. The device is disclosed.

Japanese Unexamined Patent Publication No. 2015-43526

In the electromagnetic wave energy recovery device described in Patent Document 1, power is synthesized by connecting the outputs of a plurality of rectifying units in series or in parallel, but the number of antennas that can be configured in a limited area is not large, and the above Even if the outputs of multiple rectifiers are connected in series, the obtained DC voltage is not high. Therefore, it is difficult to operate a load that requires a relatively high voltage.

Therefore, an object of the present invention is to provide an energy harvesting device capable of operating a load requiring a relatively high voltage while suppressing an increase in size.

The energy harvesting device as an example of the present disclosure is
Multiple antennas, each receiving electromagnetic energy,
A plurality of rectifier circuits connected to the plurality of antennas, converted between AC and DC of induced power, and connected in series to the output unit, and a plurality of rectifier circuits.
A plurality of booster circuits that boost the voltage of the series output section of the plurality of rectifier circuits, respectively.
A plurality of storage batteries or capacitors that are charged by the outputs of the plurality of booster circuits, respectively.
A connection state switching circuit for connecting the plurality of storage batteries or capacitors in series to a load is provided.

With the above configuration, the voltage of the series output section of the plurality of rectifier circuits is boosted by the booster circuit, and the power supply voltage is supplied to the load by connecting multiple storage batteries or capacitors in series while supplying the power supply voltage to the load. Will be done.

According to the energy harvesting device of the present invention, it is possible to operate a load that requires a relatively high voltage while suppressing the increase in size.

FIG. 1 is a block diagram showing a configuration of an energy harvesting device and a sensor according to the first embodiment. FIG. 2 is a front view of the environment sensor 201 according to the first embodiment. FIG. 3 is a cross-sectional view of the environment sensor 201. FIG. 4 is a circuit diagram of the environment sensor 201. FIG. 5 is a diagram showing a rectifier circuit according to the second embodiment. FIG. 6 is a diagram showing another rectifier circuit according to the second embodiment. FIG. 7 is a front view of the environment sensor 203A according to the third embodiment. FIG. 8 is a front view of another environment sensor 203B according to the third embodiment.

First, some aspects of the energy harvesting apparatus according to the present invention will be listed.

The environmental power generation device according to the first aspect of the present invention is connected to a plurality of antennas, each of which receives electromagnetic energy, and a plurality of antennas, the induced power is converted into AC / DC, and the output units are connected in series. A rectifier circuit, a plurality of booster circuits for boosting the voltage of the series output units of the plurality of rectifier circuits, a plurality of storage batteries or capacitors charged by the outputs of the plurality of booster circuits, and the plurality of storage batteries or capacitors. It is equipped with a connection state switching circuit that connects in series and connects to a load. With this configuration, the storage battery or capacitor is charged with the voltage boosted by the plurality of booster circuits, and the power supply voltage is supplied to the load by connecting the plurality of storage batteries or capacitors in series while supplying the power supply voltage to the load. Therefore, a load requiring a relatively high voltage can be operated with a relatively small number of antennas.

In the energy harvesting device according to the second aspect of the present invention, the plurality of antennas include antennas that receive electromagnetic waves having a plurality of transport frequencies having different transport frequencies. According to this structure, the energy of a plurality of electromagnetic waves having different purposes such as broadcasting and communication can be recovered at the same time.

In the energy harvesting device of the third aspect according to the present invention, each of the plurality of antennas is a loop antenna connected to a common planar conductor composed of a conductor film or a conductor layer. According to this structure, the placement space of the plurality of antennas is reduced.

In the energy harvesting device of the fourth aspect according to the present invention, each of the plurality of antennas is a loop antenna formed of a common planar conductor composed of a conductor film or a conductor layer. According to this structure, the placement space of the plurality of antennas is reduced. Further, even if a plurality of antennas are close to each other, interference between the antennas can be suppressed.

In the environmental power generation device according to the fifth aspect of the present invention, the planar conductor is a ground conductor of the plurality of rectifier circuits or a ground conductor of the plurality of booster circuits, or a ground conductor of the plurality of rectifier circuits and the plurality of ground conductors. It is the ground conductor of the booster circuit of. According to this structure, a plurality of antennas can be integrated together with a plurality of rectifier circuits or a plurality of booster circuits, and the arrangement space of the plurality of antennas can be reduced. In addition, interference between a plurality of antennas can be suppressed.

Hereinafter, a plurality of embodiments for carrying out the present invention will be shown with reference to the drawings with reference to some specific examples. The same reference numerals are given to the same parts in each figure. Although the embodiments are shown separately for convenience of explanation in consideration of the explanation of the main points or the ease of understanding, partial replacement or combination of the configurations shown in different embodiments is possible. In the second and subsequent embodiments, the description of matters common to the first embodiment will be omitted, and only the differences will be described. In particular, the same action and effect due to the same configuration will not be mentioned sequentially for each embodiment.

<< First Embodiment >>
FIG. 1 is a block diagram showing a configuration of an energy harvesting device and an environment sensor according to the first embodiment. The environment sensor 201 is composed of an energy harvesting device 101 and a load 50. The energy harvesting device 101 includes antennas 11 to 14, rectifier circuits 21 to 24, booster circuits 31 and 32, and storage batteries 41 and 42. A load 50 is connected to the energy harvesting device 101.

The antennas 11 to 14 are, for example, loop antennas, as illustrated later, and each receives electromagnetic energy. For example, the antenna 11 receives a terrestrial digital broadcast wave in a predetermined frequency band having a center frequency of 550 MHz. The antenna 12 receives the communication wave of the 2.4 GHz band wireless LAN. The antenna 13 receives a transmission wave of a mobile phone base station in a predetermined frequency band having a center frequency of 920 MHz. Further, the antenna 14 receives the communication wave of the wireless LAN in the 5 GHz band.

The rectifying circuits 21 to 24 are connected to the antennas 11 to 14, respectively, and rectify (AC-DC conversion) the induced power (voltage) of the antennas 11 to 14, respectively. The output units of these rectifier circuits 21 to 24 are connected in series.

The booster circuits 31 and 32 boost the voltage of the series output section of the rectifier circuits 21 to 24, respectively. The storage battery is, for example, a lithium ion secondary battery, and is charged by the booster circuits 31 and 32, respectively.

As will be shown later, the energy harvesting device 101 further includes a connection state switching circuit for connecting the storage batteries 41 and 42 in series to the load when supplying the outputs of the storage batteries 41 and 42 to the load 50.

The load 50 is a circuit including, for example, sensors for temperature, humidity, etc., and wirelessly transmits measurement data under predetermined conditions.

FIG. 2 is a front view of the environment sensor 201 according to the first embodiment. FIG. 3 is a cross-sectional view of the environment sensor 201.

The environment sensor 201 is a device in which the energy harvesting device 101 shown in FIG. 1 and the load 50 are integrated. As shown in FIG. 2, the environment sensor 201 includes a substrate 9, and antenna conductor patterns 11a, 11b, 12a, 12b, 13a, 13b, 14a, 14b and a planar conductor 10 are provided on the first surface of the substrate 9. It is formed. These antenna conductor patterns 11a, 11b, 12a, 12b, 13a, 13b, 14a, 14b and the planar conductor 10 are, for example, patterns made of Cu foil. Further, rectifier circuit modules 21M, 22M, 23M, 24M are mounted on the first surface of the substrate 9. In FIG. 2, the rectifier circuit modules 21M, 22M, 23M, and 24M are represented by broken lines.

The antenna conductor patterns 11a and 11b and the planar conductor 10 form one loop antenna (antenna 11 in FIG. 1). Further, one loop antenna (antenna 12 in FIG. 1) is composed of the antenna conductor patterns 12a and 12b and the planar conductor 10. Similarly, one loop antenna (antenna 13 in FIG. 1) is composed of the antenna conductor patterns 13a and 13b and the planar conductor 10. Further, one loop antenna (antenna 14 in FIG. 1) is composed of the antenna conductor patterns 14a and 14b and the planar conductor 10.

As shown in FIG. 3, a booster circuit 31, a storage battery 41, and the like are provided on the second surface of the substrate 9. The booster circuit 31 is composed of a DC-DC converter module. Although not shown in the cross section of FIG. 3, the booster circuit 32 and the storage battery 42 are also provided on the second surface of the substrate 9. The planar conductor 10 formed on the first surface of the substrate 9 is a ground conductor of the rectifier circuits 21 to 24 and a ground conductor of the booster circuits 31 and 32.

A resist film or a coverlay may be provided on the first surface of the substrate 9. Further, the antenna conductor patterns 11a, 11b, 12a, 12b, 13a, 13b, 14a, 14b and the planar conductor 10 may be formed by the conductor layer of the inner layer of the multilayer substrate.

In the present embodiment, since each of the antennas 11 to 14 is a loop antenna connected to a common planar conductor composed of a conductor film or a conductor layer, the arrangement space of a plurality of antennas is reduced. Further, since the planar conductor 10 is also a ground conductor of the rectifying circuits 21 to 24 and a ground conductor of the booster circuits 31 and 32, mutual interference between the antennas 11 to 14 is suppressed. Further, even if the antennas 11 to 14 are close to each other, the antennas are separated from each other via the planar conductor 10, so that mutual interference between the antennas 11 to 14 is suppressed at that point as well.

FIG. 4 is a circuit diagram of the environment sensor 201. In FIG. 4, the antennas 11 to 14 are represented by symbols of AC voltage sources, respectively. Each of the rectifier circuits 21 to 24 is a voltage doubler rectifier circuit composed of rectifier diodes D1 and D2 and capacitors C1 and C2. The outputs of these rectifier circuits 21 to 24 are connected in series.

Each of the booster circuits 31 and 32 is a boost converter composed of an input capacitor Ci, an output capacitor Co, an inductor L1, a switch element Q1, a diode D3, and a control circuit CNT. A storage battery 41 is connected to the output of the booster circuit 31, and a storage battery 42 is connected to the output of the booster circuit 32. The control circuit CNT operates using the input voltage as the power supply voltage, and controls ON / OFF of the switch element Q1 at a predetermined switching frequency.

The input units of the booster circuits 31 and 32 are connected to the series output units of the rectifier circuits 21 to 24, respectively. That is, the input portions of the booster circuits 31 and 32 are connected in parallel. However, in this example, the backflow prevention diode D14 is inserted between the ground G1 of the booster circuit 31 and the ground G2 of the booster circuit 32.

The storage batteries 41 and 42 are connected in series via the switch circuit SW. The switch circuit SW is, for example, a MOS-FET. This switch circuit SW corresponds to the "connection state switching circuit" according to the present invention. That is, in the conductive state of the switch circuit SW, the storage batteries 41 and 42 are connected in series, and the added voltage of the storage batteries 41 and 42 is supplied to the load 50 as a power supply voltage. A capacitor Cout is connected in parallel to the power supply voltage application portion of the load 50.

The load 50 includes a circuit that outputs a control signal to the switch circuit SW. In this example, when the voltage of the storage battery 42 exceeds a predetermined threshold value, the switch circuit SW is made conductive and the measured values such as temperature and humidity are wirelessly transmitted. The amount of electric power required for this wireless transmission is supplied from the storage batteries 41 and 42. One wireless transmission is completed in a very short time, and then charging of the storage batteries 41 and 42 is started again.

For example, the voltage of the series output section of the rectifying circuits 21 to 24 is 0.38V to 3.3V, the rated voltage of the storage batteries 41 and 42 is 2.3V, the upper limit charging voltage is 2.7V, and the lower limit discharging voltage is 1.8V. The rated power supply voltage of the load 50 is 3V, 200μA. The amount of power required for the wireless transmission is, for example, 5 μWh / time and 30 μW / day.

The circuit may be configured so that the voltage of the storage batteries 41 and 42 is supplied to the control circuit CNT of the booster circuits 31 and 32 as the power supply voltage. Further, the load 50 may be configured to conduct the switch circuit SW when the voltage of the capacitor Cout exceeds a predetermined threshold value.

Further, instead of the backflow prevention diode D14, a switch circuit using a MOS-FET or the like may be provided, and this switch circuit may be configured to be controlled by a control signal output from the load 50.

<< Second Embodiment >>
The second embodiment shows a rectifier circuit having a configuration different from that of the rectifier circuit shown in the first embodiment.

FIG. 5 is a diagram showing a rectifier circuit according to the second embodiment. Each of the rectifier circuits 21 and 22 is a voltage doubler rectifier circuit composed of rectifier diodes D1 and D2 and capacitors C1 and C2. The outputs of these rectifier circuits 21 and 22 are connected in series.

Similarly, an N-fold voltage rectifier circuit may be configured by comprising three or more diodes and three or more capacitors to form a Cockcroft-Walton circuit.

FIG. 6 is a diagram showing another rectifier circuit according to the second embodiment. In FIG. 6, the antennas 11 and 12 are represented as loop antennas. The rectifier circuits 21 and 22 are composed of capacitors Ca and Cb, a diode Da and a line SL. The capacitor Ca constitutes a low-pass filter. The line SL is a 1/4 wavelength line, and the line SL and the capacitor Cb form an output filter circuit. The fundamental wave input to the rectifier circuits 21 and 22 is totally reflected by the capacitor Cb, and the standing wave becomes antinode at the cathode end of the diode Da. Further, the impedance when the output filter circuit is viewed from the diode Da seems to be open for the odd harmonics of 3f, 5f, ..., And short-circuited for the even harmonics of 2f, 4f, ... A half-wave harmonic current flows through the diode Da, and the circuit as a whole is double-voltage rectified.

<< Third Embodiment >>
In the third embodiment, an antenna having a configuration different from that of the antenna shown in the first embodiment is exemplified.

FIG. 7 is a front view of the environment sensor 203A according to the third embodiment. The environment sensor 203A includes a substrate 9, and a planar conductor 10 is formed on the first surface of the substrate 9. Rectangular conductor openings H1, H2, H3, and H4 are formed in the planar conductor 10, respectively. The planar conductor 10 is, for example, a Cu foil patterned. Four loop antennas are configured by these conductor openings H1, H2, H3, and H4. That is, the inner circumferences of the conductor openings H1, H2, H3, and H4 each act as a loop antenna. The conductor opening H1 constitutes an antenna having a center frequency of 550 MHz, the conductor opening H2 constitutes an antenna having a center frequency of 920 MHz, the conductor opening H3 constitutes an antenna having a center frequency of 2.4 GHz, and the conductor opening H4 constitutes an antenna. Constructs an antenna with a center frequency of 5 GHz.

The parts marked with “+” and “-” symbols in FIG. 7 are drawn out from the second surface of the substrate 9 via a via conductor and are connected to the rectifier circuit formed on the second surface of the substrate 9, respectively. ..

A resist film or a coverlay may be provided on the first surface of the substrate 9. Further, the planar conductor 10 may be formed of a conductor layer which is an inner layer of a multilayer substrate.

In addition to the rectifier circuit, a booster circuit and a storage battery are also provided on the second surface of the substrate 9. The overall configuration of the environment sensor 203A is as shown in FIG.

For example, the output voltage of the rectifying circuit connected to the antenna by the conductor opening H1 shown in FIG. 7 is 0.1V, the output voltage of the rectifying circuit connected to the antenna by the conductor opening H2 is 0.2V, and the output voltage of the rectifying circuit by the conductor opening H3 is 0.2V. If the output voltage of the rectifying circuit connected to the antenna is 0.1V and the output voltage of the rectifying circuit connected to the antenna by the conductor opening H4 is 0.1V, 0.5V, which is the added voltage, is input to the booster circuit. Will be.

FIG. 8 is a front view of another environment sensor 203B according to the third embodiment. The environment sensor 203B includes a substrate 9, and a planar conductor 10 is formed on the first surface of the substrate 9. Rectangular conductor openings H1 to H8 are formed on the planar conductors 10, respectively. Eight loop antennas are configured by these conductor openings H1 to H8. That is, the inner circumferences of the conductor openings H1 to H8 each act as a loop antenna. All of these loop antennas act as antennas with a center frequency of 2.4 GHz.

The parts marked with “+” and “-” symbols in FIG. 8 are drawn out from the second surface of the substrate 9 via a via conductor and are connected to the rectifier circuit formed on the second surface of the substrate 9, respectively. ..

In addition to the rectifier circuit, a booster circuit and a storage battery are also provided on the second surface of the substrate 9. The overall configuration of the environment sensor 203B is as shown in FIG.

If the output voltage of the rectifier circuit connected to the antenna by the conductor openings H1 to H8 shown in FIG. 8 is, for example, 0.1V, 0.8V, which is the added voltage thereof, is input to the booster circuit.

According to the third embodiment, since the plurality of antennas can be integrated together with the plurality of rectifier circuits or the plurality of booster circuits, the arrangement space of the plurality of antennas is reduced. Further, since the planar conductor 10 is also a ground conductor of the rectifier circuit and the booster circuit, mutual interference of the antennas is suppressed. Further, even if the openings H1 to H4 and H1 to H8 are close to each other, the antennas are separated from each other via the planar conductor 10, so that mutual interference between the antennas is suppressed at that point as well.

Finally, the description of the embodiments described above is exemplary in all respects and not restrictive. Modifications and changes can be made as appropriate for those skilled in the art. The scope of the invention is indicated by the claims, not by the embodiments described above. Further, the scope of the present invention includes modifications from the embodiments within the scope of the claims and within the scope of the claims.

For example, the element charged by the booster circuit is not limited to the secondary battery, and may be a large-capacity capacitor such as an electric double layer capacitor.

In addition to the loop antenna, the antenna may be a dipole antenna or a slot antenna.

Further, the set of the booster circuit and the storage battery is not limited to two sets, and three or more sets may be provided, and the voltage of the series output unit of the plurality of rectifier circuits may be applied to the booster circuit.

Further, the planar conductor 10 may be a ground conductor of one of a plurality of rectifier circuits or a plurality of booster circuits.

In addition to the environment sensor, the energy harvesting device is a device that stores the electromagnetic wave energy of the environment at normal times and consumes it in a short time at the required time, such as a display whose display contents can be rewritten by external operation at a predetermined timing. It can be applied in the same way.

C1, C2 ... Capacitors Ca, Cb ... Capacitors Ci ... Input capacitors CNT ... Control circuit Co ... Output capacitors Cout ... Capacitors D1, D2 ... Rectifying diodes D3 ... Diodes D14 ... Backflow prevention diodes Da ... Diodes H1, H2, H3, H4 ... Conductor opening L1 ... Capacitor Q1 ... Switch element SL ... 1/4 wavelength line SW ... Switch circuit 9 ... Substrate 10 ... Planar conductors 11-14 ... Antennas 11a, 11b, 12a, 12b, 13a, 13b, 14a, 14b ... Antenna conductor patterns 21 to 24 ... rectifying circuits 21M, 22M, 23M, 24M ... rectifying circuit modules 31, 32 ... boosting circuits 41, 42 ... storage battery 50 ... load 101 ... environmental power generation device 201, 203A, 203B ... environmental sensor

Claims (5)

Multiple antennas, each receiving electromagnetic energy,
A plurality of rectifier circuits connected to the plurality of antennas, converted between AC and DC of induced power, and connected in series to the output unit, and a plurality of rectifier circuits.
A plurality of booster circuits that boost the voltage of the series output section of the plurality of rectifier circuits, respectively.
A plurality of storage batteries or capacitors that are charged by the outputs of the plurality of booster circuits, respectively.
A connection state switching circuit that connects a plurality of storage batteries or capacitors in series and connects to a load,
Energy harvesting device equipped with. The plurality of antennas include antennas that receive electromagnetic waves having a plurality of carrier frequencies having different carrier frequencies.
The energy harvesting device according to claim 1. Each of the plurality of antennas is a loop antenna connected to a common planar conductor composed of a conductor film or a conductor layer.
The energy harvesting device according to claim 1 or 2. Each of the plurality of antennas is a loop antenna formed of a common planar conductor composed of a conductor film or a conductor layer.
The energy harvesting device according to claim 1 or 2. The planar conductor is a ground conductor of the plurality of rectifier circuits or a ground conductor of the plurality of booster circuits, or a ground conductor of the plurality of rectifier circuits and a ground conductor of the plurality of booster circuits.
The energy harvesting device according to claim 3 or 4.

Images