JP2014121135A - Storage battery charging system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a storage battery charging system capable of improving battery life while achieving space saving and cost reduction.SOLUTION: A storage battery charging system includes: a vibration power generating element 10 that outputs a first AC power; a power receiving unit 20 that outputs a second AC power as a wireless power supply; a first switch SW10 for selecting either of outputs of the vibration power generating element 10 and the power receiving unit 20; a rectifier circuit 30 that converts the first AC power or the second AC power supplied through the first switch SW10 into DC power; a storage battery 50 that stores DC power; and an authentication circuit 60 that authenticates whether the wireless power supply can be performed, and switches the first switch SW10 such that power is supplied from the power receiving unit 20 when the wireless power supply can be performed and such that power is supplied from the vibration power generating element 10 when the wireless power supply cannot be performed.

Description

  The present invention relates to a storage battery charging system.

  2. Description of the Related Art Conventionally, a technique for collecting power such as sunlight, illumination light, vibration generated by a machine, or heat to obtain electric power is known (see, for example, Patent Document 1). According to such an energy harvest, a slight amount of energy around us can be converted into electric power and utilized.

Special table 2009-528209

  By the way, when energy harvesting is added as a power supply means for the storage battery in addition to normal charging, the battery life can be improved. However, when the power supply means is increased, there is a problem that the number of parts increases and the cost and space increase.

  An object of the present invention is to provide a storage battery charging system capable of improving battery life while saving space and reducing costs.

  According to an aspect of the present invention, the energy harvester element that outputs the first AC power, the wireless power receiving unit that outputs the second AC power, and the output of the energy harvester element and the power receiving unit are selected. A rectifier circuit that converts the first AC power or the second AC power supplied through the first switch into DC power, a storage battery that stores the DC power, and the wireless Authenticates whether or not power supply is possible. When the wireless power supply is possible, the first switch is switched so that power is supplied from the power receiving unit, and when the wireless power supply is not possible, the energy harvester element A storage battery charging system is provided that includes an authentication circuit that switches the first switch so that power is supplied.

  ADVANTAGE OF THE INVENTION According to this invention, the storage battery charging system which can improve battery life can be provided, aiming at space saving and cost reduction.

It is a typical circuit block diagram of the storage battery charging system which concerns on embodiment, Comprising: (a) The structural example of a storage battery charging system, (b) The example of arrangement | positioning of a feed part and a power receiving part. The specific circuit block diagram of the storage battery charging system which concerns on embodiment. The flowchart which shows operation | movement of the storage battery charging system which concerns on embodiment. The specific circuit block diagram of another storage battery charging system which concerns on embodiment. The typical circuit block diagram of the energy harvester system used with the storage battery charging system which concerns on embodiment. Waveform example of time variation of the capacitor voltages V ₁ caused by the power generation of the energy harvester system for use in battery charging system according to an embodiment. In the energy harvester system used in the storage battery charging system according to the embodiment, (a) a waveform example of time variation of the generated energy E, (b) a capacitor having values R ₁ , R ₂ and R ₃ of the load resistance R _L as parameters waveform example of time variation of the voltage V _1. The specific circuit block diagram of the energy harvester system used with the storage battery charging system which concerns on embodiment. The typical circuit block diagram of another energy harvester system used with the storage battery charging system which concerns on embodiment. The typical circuit block diagram of the energy harvester apparatus applicable to another energy harvester system used with the storage battery charging system which concerns on embodiment. In an energy harvester device applicable to another energy harvester system used in the storage battery charging system according to the embodiment, (a) operation waveform examples of the capacitor voltage V ₁ and the gate voltage V ₂ , (b) operation of the drain voltage V ₃ waveform example, (c) an operation waveform example of the supply current I ₁ to the load. In an energy harvester device applicable to another energy harvester system used in the storage battery charging system according to the embodiment, (a) ON / OFF operation waveform examples of the capacitor voltage V ₁ and the gate voltage V ₂ , (b) the drain voltage V ₃ ON / OFF operation waveform example, (c) ON / OFF operation waveform example of supply current I ₁ to the load. In another energy harvester system used in the storage battery charging system according to the embodiment, (a) a continuous operation waveform example of the gate voltage V ₂ , (b) a continuous operation waveform example of the energy E ₁ stored in the capacitor, (c) Example of continuous operation waveform of supply current I ₁ to load, (d) Example of continuous operation waveform of supply energy E _L to load. The typical circuit block diagram of another energy harvester system used with the storage battery charging system which concerns on embodiment. The typical bird's-eye view structure figure which shows a mode that the mobile telephone to which the storage battery charging system which concerns on embodiment is applied is charged by wireless electric power feeding. The figure for demonstrating the electric power transmission of the wireless electric power feeding performed with the storage battery charging system which concerns on embodiment. The storage battery charging system which concerns on embodiment, The graph which shows the relationship between a coil parameter and maximum transmission efficiency.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness of each component and the planar dimensions is different from the actual one. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  Further, the embodiments described below exemplify apparatuses and methods for embodying the technical idea of the present invention, and the embodiments of the present invention include the material, shape, and structure of each component. The arrangement is not specified below. Various modifications can be made to the embodiment of the present invention within the scope of the claims.

<< Embodiment >>
[Configuration of storage battery charging system]
A schematic circuit configuration of the storage battery charging system according to the embodiment is expressed as shown in FIG. The storage battery charging system includes an energy harvester element (vibration power generation element) 10 that outputs first AC power, a wireless power receiving unit 20 that outputs second AC power, and one of the energy harvester element 10 and the power receiving unit 20. A first switch SW10 for selecting the output, a rectifier circuit 30 for converting the first AC power or the second AC power supplied via the first switch SW10 to DC power, and a storage battery 50 for storing DC power. Whether the wireless power supply is possible or not. When the wireless power supply is possible, the first switch SW10 is switched so that power is supplied from the power receiving unit 20. When the wireless power supply is not possible, the energy harvester element 10 is switched. And an authentication circuit 60 that switches the first switch SW10 so as to be fed with power.

  Moreover, the power supply circuit 40 connected between the rectifier circuit 30 and the storage battery 50 and stabilizing DC power may be provided, and the stabilized DC power may be supplied to the storage battery 50.

  Further, the first AC power and the second AC power may have different frequencies.

  The energy harvester element 10 may be a vibration power generation element 10 that converts vibrations into first AC power and outputs the first AC power.

  Further, the vibration power generation element 10 may be any one of an electromagnetic induction type, an electret type, a piezoelectric type, and a magnetostrictive type.

  The rectifier circuit 30 may operate as a synchronous rectifier circuit when wireless power feeding is possible.

  The rectifier circuit 30 may operate as a diode bridge rectifier circuit when wireless power feeding is not possible.

  The rectifier circuit 30 may operate in a low input mode when wireless power feeding is not possible.

  The rectifier circuit 30 may include MOSFETs 31a, 31b, 31c, and 31d having a bridge structure.

  Moreover, you may provide the load which is the supply destination of the electric power stored in the storage battery 50. FIG.

  The load may be a mobile phone, an audio device, a game device, a tablet terminal, a pedometer (registered trademark), an electric vehicle, or a component of those devices.

  As shown in FIG. 1A, the storage battery charging system according to the embodiment includes a vibration power generation element 10, a power receiving unit 20, a first switch SW10, a rectifier circuit 30, a power supply circuit 40, and a storage battery 50. And an authentication circuit 60. The vibration power generation element 10 converts the vibration into first AC power and outputs it. The vibration power generation methods include an electromagnetic induction type, an electret type, a piezoelectric type, and a magnetostrictive type. The power receiving unit 20 is a power receiving unit for wireless power feeding, and outputs second AC power. For example, as illustrated in FIG. 1B, when the power receiving unit 20 is disposed in the vicinity of the power feeding unit 21 included in the wireless charger, the power feeding coil 14 on the power feeding unit 21 side and the power receiving coil 16 on the power receiving unit 20 side are arranged. Electric power transmission by power feeding is performed by electromagnetic coupling (described later). The first AC power and the second AC power may have different frequencies. For example, the frequency of the first AC power can be selected from various frequency bands. On the other hand, if a high frequency band such as a megahertz band is used as the frequency of the second AC power, the inductance can be reduced. The first switch SW10 is a switch for selecting one of the outputs from the vibration power generation element 10 and the power receiving unit 20. The rectifier circuit 30 converts the first AC power or the second AC power supplied via the first switch SW10 into DC power. The power supply circuit 40 is a circuit that stabilizes DC power, and includes a step-down regulator, a battery monitoring / protection circuit, and the like. The storage battery 50 is a lithium ion battery or the like that stores stabilized DC power. The authentication circuit 60 communicates with a power supply side device such as a wireless charger, and exchanges information such as coil positioning and power supply wattage to authenticate whether wireless power supply is possible. When wireless power feeding is possible, the first switch SW10 is switched so that power is supplied from the power receiving unit 20, and when wireless power feeding is not possible, the first switch SW10 is switched so that power is supplied from the vibration power generation element 10. Although not shown, a load that is a power supply destination is connected to the subsequent stage of the storage battery 50. This load is, for example, a mobile phone, an audio device, a game device, a tablet terminal, a pedometer (registered trademark), an electric vehicle, or a component of those devices.

A specific circuit configuration of the storage battery charging system according to the embodiment is expressed as shown in FIG. As shown in FIG. 2, the contacts (A) of the first switches SW11 and SW12 are connected to the power receiving coil 16, and the contacts (B) of the first switches SW11 and SW12 are connected to the vibration power generation element 10. The first switches SW11 and SW12 are connected to bridge-structure MOSFETs 31a, 31b, 31c and 31d (hereinafter sometimes referred to as “converter 31”). The gates of the MOSFETs 31a, 31b, 31c, and 31d are connected to the synchronous rectification controller 32, and are on / off controlled by the synchronous rectification controller 32. A rectifier circuit 30 is formed by the converter 31 and the synchronous rectifier controller 32. When the MOSFETs 31a, 31b, 31c, and 31d are off, the rectifier circuit 30 operates as a diode bridge rectifier circuit. Converter 31 is connected to storage battery 50 via bypass capacitor C ₁₂ and power supply circuit 40. The power receiving coil 16 and the resonant capacitor C ₁₁ form a parallel resonant circuit, and the authentication circuit 60 is connected to the parallel resonant circuit. The authentication circuit 60 authenticates whether or not wireless power feeding is possible, and controls the first switches SW11 and SW12 and the synchronous rectification controller 32 based on the authentication result. That is, at the time of wireless power feeding, for example, relatively large power of about 5 W to 10 W can be handled, so the rectifier circuit 30 is operated as a synchronous rectifier circuit. On the other hand, at the time of vibration power generation, only relatively small power of, for example, several tens of μW to 1 mW can be handled, so that synchronous rectification is stopped and the rectifier circuit 30 is operated as a diode bridge rectifier circuit. During vibration power generation, the operation mode of the rectifier circuit 30 may be switched to operate in the low input mode.

  Here, the converter 31 is configured using four MOSFETs 31a, 31b, 31c, and 31d, but the number of MOSFETs 31a, 31b, 31c, and 31d can be changed as appropriate. Further, instead of the MOSFETs 31a, 31b, 31c, and 31d, for example, transistors such as silicon carbide (silicon carbide: SiC) and nitride semiconductor (gallium nitride: GaN) can be used.

[Operation of storage battery charging system]
The operation of the storage battery charging system according to the embodiment is expressed as shown in FIG.

  First, the authentication circuit 60 communicates with a power supply side device such as a wireless charger, and authenticates whether wireless power supply is possible (step S1). If wireless power feeding is possible (step S1: Yes), the contact (A) of the first switches SW11 and SW12 is turned on (step S2), and an enable signal is transferred to the synchronous rectification controller 32 (step S3). ). On the other hand, when wireless power feeding is not possible (step S1: No), the contact (B) of the first switches SW11 and SW12 is turned on (step S5), and a disable signal is transferred to the synchronous rectification controller 32 (step S6). ).

  Next, when receiving the enable signal from the authentication circuit 60, the synchronous rectification controller 32 controls the gates of the MOSFETs 31a, 31b, 31c, and 31d to operate on the synchronous rectification method at a necessary timing. In this state, since the contact (A) of the first switches SW11 and SW12 is turned on, the second AC power output from the power receiving coil 16 is input to the MOSFETs 31a, 31b, 31c, and 31d, and is synchronously rectified. It is converted into DC power (step S4).

  On the other hand, when the synchronous rectification controller 32 receives the disable signal from the authentication circuit 60, the synchronous rectification controller 32 turns off the switching of the MOSFETs 31a, 31b, 31c, and 31d and operates the diode rectification method. In this state, since the contact (B) of the first switches SW11 and SW12 is turned on, the first AC power output from the vibration power generation element 10 is input to the MOSFETs 31a, 31b, 31c, and 31d, and the diode rectification method Is converted into DC power (step S7).

MOSFET31a, 31b, 31c, DC power output from 31d is stabilized in the bypass capacitor C ₁₂ and the power supply circuit 40, are accumulated in the accumulator 50. When such a storage battery charging system is applied to a mobile phone, not only can the storage battery 50 be charged by wireless power feeding, but the storage battery 50 is supplementarily charged by vibration caused by walking while carrying the mobile phone. Is possible.

[Modification of storage battery charging system]
A specific circuit configuration of another storage battery charging system according to the embodiment is expressed as shown in FIG. As shown in FIG. 4, Schottky barrier diodes BD1, BD2, BD3, and BD4 may be connected between the sources and drains of MOSFETs 31a, 31b, 31c, and 31d. In this way, the voltage drop can be reduced compared to the case where the Schottky barrier diodes BD1, BD2, BD3, and BD4 are not connected. Since other points are the same as those in FIG. 2, detailed description thereof is omitted here.

  As described above, in the storage battery charging system according to the embodiment, focusing on the fact that the output of vibration power generation and wireless power feeding are both AC power, the rectification circuit / power circuit of vibration power generation and the rectifier circuit / power supply of wireless power feeding The circuit is shared. Therefore, it is possible to improve the battery life while switching between vibration power generation and wireless power feeding to save space and reduce costs.

[Energy Harvest]
1 to 4 exemplify the vibration power generation element 10 as the energy harvester element, the same effect can be obtained if the energy harvester element outputs AC power. It is also possible to construct energy harvester systems with various configurations using such energy harvester elements. Hereinafter, the energy harvester system used in the storage battery charging system according to the embodiment will be described in detail.

(Energy harvester system)
As shown in FIG. 5, the energy harvester system 10 a used in the storage battery charging system according to the embodiment is charged with energy generated by the energy harvester element 4 and the energy harvester element 4 connected in parallel to the energy harvester element 4. And a load R _L connected in parallel to the capacitor 3. Here, C ₁ and the value of the capacitor 3, when the charging voltage and V _1, the energy charged in the capacitor C ₁ is represented by CV ₁ ^2/2.

In the energy harvester system 10a, a waveform example of the time variation of the capacitor voltages V ₁ caused by the power generation of the load values of _{R L R 1, R 2,} R 3 (R 1 <R 2 <R 3) and parameter 6 It is expressed as shown in

6, the capacitor voltages V ₁ at time tp, the load R value R ₁ of the _{L, R 2, R 3 (} R 1 <R 2 <R 3) relative to each peak value V _p1, V _p2, V _p3 is shown. Here, in the example shown in FIG. 6, the time at which the peak value of the capacitor voltage V ₁ is obtained is set to the same time tp, but the time at which the peak value is obtained may not necessarily match. .

In the energy harvester system 10a, as shown in FIG. 6, the smaller the impedance of the load R _L , the more the peak value of the capacitor voltage V ₁ changes as V _p1 <V _p2 <V _{p3. The} energy stored in ₁ is reduced. As a result, the amount of energy supplied from the energy harvester element 4 to the load R _L1 is also reduced. That is, in the energy harvester element 4, the power generation efficiency varies depending on the impedance of the target to which the generated energy is supplied.

Moreover, in the energy harvester system 10a, the waveform example of the time change of the generated energy E is represented as a vibration waveform having a peak value E _p at the time tp as shown in FIG. 7A, for example.

Further, a waveform example of the time change of the capacitor voltage V _{1 using} the load resistance R _L as a parameter is expressed as shown in FIG. In the energy harvester system 10a, the RC time constant changes according to the value of the load resistance R _L , and the relationship R ₁ C ₁ <R ₂ C ₁ <R ₃ C ₁ is established. For this reason, when the value of the load resistance R _L is large, it takes time to charge the capacitor C ₁ .

As shown in FIG. 8, a specific circuit configuration example of the energy harvester system 10a includes an energy harvester element 4 and a capacitor connected in parallel to the energy harvester element 4 for charging energy generated by the energy harvester element 4. 3, a power supply 5 connected in parallel to the capacitor 3, and a system load 6 connected to the power supply 5. Here, the impedance on the power source 5 side including the system load 6 viewed from the capacitor 3 is represented by R _L1 , and the impedance of the system load 6 is represented by R _L2 .

In order to properly drive such a load R _L (impedance on the power source 5 side is R _L1 and impedance of the system load 6 is R _L2 ), it is necessary to supply necessary energy to the load R _L. However, when the impedance of the load R _L is high, it takes time to charge the capacitor C ₁ as shown in FIG. For this reason, it is necessary to switch the impedance of the load R _L appropriately to shorten the time constant. That is, in order to supply sufficient energy to the electronic device, while ensuring shorter charging time of the capacitor C _1, effectively needs to be supplied to the power generation energy of the energy harvester device 4 charged in the capacitor C ₁ to the load R _L There is.

(Variation 1 of energy harvester system)
As shown in FIG. 9, another energy harvester system 10 b used in the storage battery charging system according to the embodiment includes an energy harvester element 4, an energy harvester apparatus 1 connected to the energy harvester element 4, and an energy harvester apparatus 1. And a load 7 that is a connected energy supply destination.

  Here, the load 7 includes a power source 5 and a system load 6 connected to the power source 5 and consuming power. The power supply 5 has a function of stabilizing the supply voltage to the system load. The power source 5 is a supply voltage stabilized power source such as a DC-DC converter, LDO (Low Drop Out), or the like. The system load 6 is a mobile device such as a mobile phone, a smartphone, a PDA, an optical disk device, a digital camera, and a wireless communication device, an automobile, an industrial device, a medical device, and a component part of those devices, and consumes energy. Equipment.

(Energy harvester device)
A schematic circuit configuration of the energy harvester apparatus 1 applicable to the energy harvester system 10b is expressed as shown in FIG.

As shown in FIGS. 9 and 10, the energy harvester device 1 applicable to the energy harvester system 10 b is connected to the energy harvester element 4, and includes a capacitor 3 that stores energy generated by the energy harvester element 4, and a capacitor 3. And a second switch 2 that switches the energy supply from the capacitor 3 to the seven loads based on the capacitor voltage V ₁ charged in the capacitor 3.

The second switch 2 is connected between the capacitor 3 and the load 7 and switches power supply from the capacitor 3 to the load 7 based on the capacitor voltage V ₁ .

Here, as shown in FIG. 10, the second switch 2 includes resistors R ₁ and R ₂ connected in parallel to the capacitor 3.

As shown in FIG. 10, the second switch includes a p-channel first insulated gate field effect transistor (MOSFET: Metal-Oxide Semiconductor Field) having a first source connected to the capacitor 3 and a first drain connected to the load 7. The second drain is connected to the first transistor R ₁ and the second resistor R ₂ that are connected in parallel to the Effect Transistor) Q ₁ and the capacitor 3 and divide the capacitor voltage V ₁ , and the first gate of the first MOSFET Q ₁ , An n-channel second MOSFET Q ₂ whose _second gate is connected to the divided voltage of the capacitor voltage V _{1 and} whose second source is the ground potential, and a third connected between the first gate and the first source of the first MOSFET Q ₁ . A resistor R ₃ may be provided. Here, the gate voltage V ₂ which is divided by a first resistor R ₁ and a second resistor R ₂ is represented by _{R 2 · V 1 / (R} 1 + R 2). The voltage of the first gate of the first MOSFET Q ₁ and the second drain of the second MOSFET Q ₂ is represented by the drain voltage V ₃ . In FIG. 10, BD ₁ represents the back gate body diode of the p-channel first MOSFET Q ₁ . In a state where a predetermined capacitor voltages V ₁ to the capacitor 3 is charged, in the first 1MOSFETQ ₁ is turned off, between the gate and source of 1MOSFETQ ₁ reverse bias is applied, between the first 1MOSFETQ ₁ of the drain-source and back A reverse bias is also applied to the gate body diode BD ₁ .

The resistors R ₁ and R ₂ have a resistance value equal to or higher than a predetermined impedance. That is, the resistance value is equal to or higher than a predetermined impedance depending on the values of the resistance R ₁ and the resistance R ₂ .

In the second switch 2, the gate voltage V ₂ = R ₂ · V ₁ / (R ₁ + R ₂ ) of the divided voltage and the threshold voltage V _th2 of the n-channel second MOSFET Q ₂ are set according to the magnitude relationship of the second MOSFET Q ₂ . The on / off state can be adjusted.

In the energy harvester device 1 applicable to the energy harvester system 10b, the operation waveform examples of the capacitor voltage V ₁ and the gate voltage V ₂ are expressed as shown in FIG. 11A, and the operation waveform example of the drain voltage V ₃ is 11 (b), and an example of the operation waveform of the supply current I ₁ to the load 7 is represented as shown in FIG. 11 (c).

In the energy harvester system 10b, in a high impedance state, since it started the capacitor voltage V _1, it can be efficiently launch later stage.

First, until time t1, as shown in FIGS. 11A and 11B, the gate voltage V ₂ is not generated with a voltage equal to or higher than the threshold voltage V _{th2 of the second} MOSFET Q ₂ . For this reason, the second MOSFET Q ₂ is turned off.

Next, as shown in FIG. 11 (a) and FIG. 11 (b), the capacitor voltage V ₁ increases with the passage of time t, and the gate voltage V ₂ = R ₂ · V ₁ / (R ₁ + R ₂ ) at time t1, it becomes higher than the threshold voltage V _th2 of the 2MOSFETQ _2, the 2MOSFETQ ₂ is turned on. As a result, the drain voltage V ₃ becomes the ground potential, and the gate potential of the first gate of the first MOSFET Q ₁ becomes equal to the drain voltage V _{3 of the second} MOSFET Q ₂ , so that the p-channel first MOSFET Q ₁ is turned on. As a result, the energy charged in the capacitor 3 is supplied to the load 7 via the _first MOSFET Q1. Here, as shown in FIG. 11C, the supply current I ₁ to the load 7 that conducts the _first MOSFET Q ₁ is represented by the on-current I _ON in the on-state.

In the energy harvester device 1 applicable to the energy harvester system 10b, an on / off operation waveform example of the capacitor voltage V ₁ and the gate voltage V ₂ is represented as shown in FIG. 12A, and an on / off operation waveform of the drain voltage V _3. An example is represented as shown in FIG. 12B, and an example of an on / off operation waveform of the supply current I ₁ to the load 7 is represented as shown in FIG. Since the on operation is the same as that in FIG. 11, the description is omitted, and the off operation will be described.

As shown in FIGS. 12A and 12B, the value of the capacitor voltage V ₁ charged in the capacitor 3 decreases with the passage of time t, and the gate voltage V ₂ becomes the threshold voltage V _{th2 of the second} MOSFET Q _2. becomes lower than, the 2MOSFETQ ₂ is turned off, becomes higher high-level potential than the drain voltage V ₃ is the threshold voltage V _th2, the 1MOSFETQ ₁ of p-channel is turned off. As a result, as shown in FIG. 12C, the supply current I ₁ to the load 7 that conducts the _first MOSFET Q ₁ is cut off, and the current supply to the load 7 is stopped. Since the waveform of the drain voltage V ₃ after time t2 is equal to the waveform of the capacitor voltage V ₁ , it converges to 0V as shown in FIG. At time t2, the gate-source voltage V _GS to 0V of the 1MOSFETQ _1, first 1MOSFETQ ₁ is because off.

In the energy harvester system 10b, a continuous waveform example of the gate voltage V ₂ is represented as shown in FIG. 13A, and a continuous operation waveform example of the energy E ₁ stored in the capacitor 3 is shown in FIG. 13B. The continuous operation waveform example of the supply current I ₁ to the load 7 is expressed as shown in FIG. 13C, and the continuous operation waveform example of the supply energy E _L to the load 7 is shown in FIG. It is expressed as shown in d).

With the continuous operation capacitor voltage V _1, a continuous waveform of the gate voltage V ₂ is changed as shown in FIG. 13 (a), the value of the gate voltage V ₂ is higher than the threshold voltage V _th2 of the 2MOSFETQ _2, the 2MOSFETQ ₂ is turned on, the 1MOSFETQ ₁ also turned on, the supply current I ₁ to the load 7, the oN current I _oN or oN current I _oN more current conduction. As a result, the supply energy E _L to the load 7 is represented by a continuous waveform example as shown in FIG.

  According to the energy harvester system 10b, since the energy can be supplied to the load 7 in a high impedance state after being sufficiently stored in the capacitor 3, the energy generated by the energy harvester element 4 is efficiently supplied to the load 7. can do.

  According to the energy harvester system 10b, an energy harvester device and an energy harvester system that can efficiently supply energy generated by the energy harvester element can be provided.

(Variation 2 of energy harvester system)
Schematic circuit configuration of still another energy harvester system 10c used in battery charging system according to the embodiment, as shown in FIG. 14, a plurality of energy harvester device 4 _1, 4 _2, ..., and 4 _n, a plurality of energy harvester device 4 _1, 4 _2, ..., 4 are connected to the _n, a plurality of energy harvester device 4 _1, 4 _2, ..., 4 energy harvester device provided corresponding to the _n 1 _11, 1 _12, ... , 1 _1n and loads 7 (5 ₁ , 5 ₂ ,..., 5 _n , 6) that are energy supply destinations connected to the energy harvester devices 1 ₁₁ , 1 _{12 ,.}

Here, as shown in FIG. 14, the load 7 includes a plurality of power supplies 5 ₁ , 5 ₂ ,... 5 _n connected to a plurality of energy harvester devices 1 ₁₁ , 1 _{12 ,.} power 5 _1, 5 _2, ..., are connected in common to 5 _n, and a system load 6 consumes power.

  The power supply 5 has a function of stabilizing the supply voltage to the system load 6. The power source 5 is a supply voltage stabilized power source such as a DC-DC converter, LDO (Low Drop Out), or the like.

  The system load 6 is a mobile device such as a mobile phone, a smartphone, a PDA, an optical disk device, a digital camera, and a wireless communication device, an automobile, an industrial device, a medical device, and a component part of those devices, and consumes energy. Equipment.

Further, a plurality of energy harvester device _{1 11, 1 12, ...,} 1 1n is provided with a capacitor C _1, respectively, the second switch SW1, SW2 connected to the capacitor C _1, ..., and SWn. A plurality of energy harvester device 4 _1, 4 _2, ..., the power generation state of the 4 _n, and each capacitor C _1, the capacitor voltage _{V 11, V 12, ...,} V 1n has occurred, the second switch SW1, SW2, ..., by the switching operation of SWn, relative to energy supply destination in a load 7 (5,6), a plurality of energy harvester device 4 _1, 4 _2, ..., any one or energy from a plurality of 4 _n Supply is made.

According to the energy harvester system 10c, a plurality of energy harvester device _{4 1, ..., 4 i,} ..., a plurality of energy harvester device 1 ₁₁ provided corresponding to _{4 n, ..., 1 1i,} ..., 1 1n Can be supplied to the load 7 (5 ₁ , 5 ₂ ,..., 5 _n , 6) in a high impedance state after being sufficiently stored in each capacitor 3, the plurality of energy harvester elements 4 ₁ , .., 4 _i ,..., 4 _n can be efficiently supplied to the load 7.

  According to the energy harvester system 10c, an energy harvester device and an energy harvester system capable of efficiently supplying energy generated by a plurality of energy harvester elements can be provided.

[Wireless power supply]
A schematic bird's-eye view structure showing a state in which the mobile phone 11 to which the storage battery charging system according to the embodiment is applied is charged by wireless power feeding is expressed as shown in FIG. As shown in FIG. 15, power transmission PT is performed wirelessly between the wireless charger 12 and the mobile phone 11. At this time, data transmission DT may be performed wirelessly (fiberless) by optical communication.

  The power transmission PT of wireless power feeding performed in the storage battery charging system according to the embodiment is expressed as shown in FIG. As shown in FIG. 16, power transmission PT is performed by power feeding by electromagnetic coupling between a power feeding (primary side) coil 14 and a power receiving (secondary side) coil 16.

In the storage battery charging system according to the embodiment, a graph showing the relationship between the coil parameter α by wireless power feeding and the maximum transmission efficiency η _MAX is expressed as shown in FIG.

Here, the inductance of the power supply coil 14 L1, r ₁ series resistance, inductance L2 of the power receiving coil 16, when the series resistance and r _2, the feeding coil 14, the value to Q ₁ Q of the power receiving coil 16 (Quality Factor) , Q ₂ are represented by the formulas (1) and (2).

Q ₁ = ωL1 / r ₁ (1)
Q ₂ = ωL2 / r ₂ (2)
Further, when the mutual inductance of the feeding coil 14 and the receiving coil 16 is M, the coil parameter α is expressed by the equation (3), and the maximum transmission efficiency η _MAX is expressed by the equation (4).

α≡k ² Q ₁ Q ₂ (3)
η _MAX = α / [1+ (1 + α) ^1/2 ] ² (4)
Here, k is a coupling coefficient between the feeding coil 14 and the receiving coil 16. That is, as shown in FIG. 17, the coil parameters α by feeding dominates the maximum transmission efficiency eta _MAX, the coil parameters α maximum transmission efficiency eta _MAX is close to 100% in about 10 ⁴ or more. In order to increase the value of the coil parameter α, it is preferable to increase the frequency ω from the form of the equation of ωL / r representing the Q value of the coil. In order to increase the value of the coil parameter α, there is a means of increasing the value L of the coil inductance. However, this increases the coil, which is particularly preferable for a device that features “smallness” such as a mobile device. Not that. If the switching elements (field effect transistors Q1 and Q2) in the power supply unit 21 are made of silicon, it is difficult to increase the frequency ω. Therefore, in this embodiment, such field effect transistors Q1 and Q2 are made of a gallium nitride (GaN) material. As a result, since the frequency ω can be increased as compared with the case where silicon is used, the value of the coil parameter α can be increased, and the maximum transmission efficiency η _MAX can be increased.

  As described above, according to the present invention, it is possible to provide a storage battery charging system that can improve battery life while saving space and reducing costs.

[Other embodiments]
As mentioned above, although this invention was described by embodiment, the description and drawing which make a part of this indication are an illustration, Comprising: It should not be understood that this invention is limited. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  As described above, the present invention includes various embodiments not described herein.

  The storage battery charging system according to the present invention can be used for a mobile phone, an audio device, a game device, a tablet terminal, a pedometer (registered trademark), an electric vehicle, a component of those devices, and the like.

20 ... Power receiving unit 30 ... Rectifier circuit 31a, 31b, 31c, 31d ... MOSFET (transistor)
40 ... power supply circuit 50 ... storage battery 60 ... authentication circuit 10 ... vibration power generation element (energy harvester element)
SW10, SW11, SW12 ... first switches BD1, BD2, BD3, BD4 ... Schottky barrier diodes 1, 1 ₁₁ , ... 1 _1i , ... 1 _1n ... energy harvester devices 2, SW1, ..., SWi, ..., SWn ... second switch 3, 3 ₁ , 3 ₂ , ... 3 _i , ... 3 _n ... capacitor (C ₁ )
_{4,4 1, 4 2, ...,} 4 i, ..., 4 n ... energy harvester device 7 ... load _{V 1, V 11, ...,} V 1i, ..., V 1n ... capacitor voltage Q _1, Q ₃ ... pMOSFET
Q ₂ ... nMOSFET
R ₁ , R ₂ , R ₃ ... resistance

Claims (17)

An energy harvester element that outputs first AC power;
A power receiving unit for wireless power feeding that outputs second AC power;
A first switch for selecting an output of either the energy harvester element or the power receiving unit;
A rectifier circuit for converting the first AC power or the second AC power supplied through the first switch into DC power;
A storage battery for storing the DC power;
Whether the wireless power supply is possible is authenticated, and if the wireless power supply is possible, the first switch is switched so that power is supplied from the power receiving unit, and if the wireless power supply is not possible, the energy harvester And an authentication circuit that switches the first switch so that power is supplied from the element.   The power supply circuit which stabilizes the said DC power is connected between the said rectifier circuit and the said storage battery, The said DC power stabilized is supplied to the said storage battery, The Claim 1 characterized by the above-mentioned. The storage battery charging system described.   The storage battery charging system according to claim 1 or 2, wherein the first AC power and the second AC power have different frequencies.   4. The storage battery charging system according to claim 1, wherein the energy harvester element is a vibration power generation element that converts vibration into the first AC power and outputs the first AC power. 5.   The storage battery charging system according to claim 4, wherein the vibration power generation element is one of an electromagnetic induction type, an electret type, a piezoelectric type, and a magnetostrictive type.   The storage battery charging system according to any one of claims 1 to 5, wherein the rectifier circuit operates as a synchronous rectifier circuit when the wireless power feeding is possible.   The storage battery charging system according to any one of claims 1 to 5, wherein the rectifier circuit operates as a diode bridge rectifier circuit when the wireless power feeding is not possible.   The storage battery charging system according to any one of claims 1 to 5, wherein the rectifier circuit operates in a low input mode when the wireless power feeding is not possible.   The storage battery charging system according to claim 1, wherein the rectifier circuit includes a transistor having a bridge structure.   The storage battery charging system according to claim 9, wherein a Schottky barrier diode is connected between a source and a drain of the transistor.   The storage battery charging system according to any one of claims 1 to 10, further comprising a load that is a supply destination of electric power stored in the storage battery.   The storage battery according to claim 11, wherein the load is any one of a mobile phone, an audio device, a game device, a tablet terminal, a pedometer (registered trademark), an electric vehicle, and a component of those devices. Charging system. An energy harvester device connected to the energy harvester element;
The energy harvester device is:
A capacitor for storing energy generated by the energy harvester element;
A second switch connected to the capacitor and switching energy supply from the capacitor to a load based on a capacitor voltage charged in the capacitor. The storage battery charging system described.   The storage battery charging system according to claim 13, wherein the second switch includes a resistor connected in parallel to the capacitor.   The storage battery charging system according to claim 14, wherein the resistor has a resistance value equal to or higher than a predetermined impedance. The second switch is
A p-channel first MOSFET with a first source connected to the capacitor and a first drain connected to the load;
A first resistor and a second resistor connected in parallel to the capacitor and dividing the capacitor voltage;
An n-channel second MOSFET having a second drain connected to the first gate of the first MOSFET, a second gate connected to the divided voltage of the capacitor voltage, and a second source at a ground potential;
The storage battery charging system according to claim 13, further comprising: a third resistor connected between a first gate and a first source of the first MOSFET. The second switch is
A p-channel first transistor disposed between the first source and the capacitor, having a third drain connected to the capacitor, a third source connected to the first source, and a third gate connected to the first gate; The storage battery charging system according to claim 16, further comprising 3MOSFET.

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