JP7021308B2 - Power generation system - Google Patents

Description

Embodiments of the present invention relate to a power generation system.

The vibration power generator uses environmental vibration (for example, vibration of a car or train, vibration of rain hitting the ground) to generate electricity. The electric power generated by the vibration power generator is expected to be a substitute for a power source (for example, a battery) used for a device such as a sensor.

In the vibration power generator, the displacement amplitude of the movable part changes according to the magnitude of the external vibration. If the displacement amplitude becomes too large, the vibration power generator may fail due to the movable part colliding with the housing.

Japanese Patent No. 5405127

An object to be solved by the present invention is to provide a power generation system in which an excessive displacement amplitude is avoided.

The power generation system according to one embodiment includes a generator, a displacement measuring unit, and a converter. The generator includes a moving part and converts the mechanical energy of the moving part into electric power. The displacement measuring unit measures the displacement of the movable portion. The converter includes a switching circuit whose duty ratio is controlled based on the measured displacement and transforms the power.

The functional block diagram which shows the power generation system which concerns on 1st Embodiment. The cross-sectional view which shows the structural example of the vibration power generator shown in FIG. The figure which shows an example of the converter shown in FIG. The figure explaining the switching operation of the switching circuit shown in FIG. 3A. The figure which shows the electric circuit of the power generation system shown in FIG. The flowchart which shows the operation procedure of the power generation system shown in FIG. The figure which shows the relationship of the displacement, the reference displacement, and the impedance of the movable part which concerns on 1st Embodiment. The functional block diagram which shows the power generation system which concerns on the modification of 1st Embodiment. The functional block diagram which shows the power generation system which concerns on 2nd Embodiment. The flowchart which shows the operation procedure of the power generation system shown in FIG. The figure which shows the relationship of the displacement absolute value, the reference displacement and the impedance which concerns on the 2nd Embodiment. The figure which shows the relationship between the displacement absolute value and impedance which concerns on 2nd Embodiment. The functional block diagram which shows the power generation system which concerns on the modification of 2nd Embodiment. The figure explaining the operation of the power generation system shown in FIG. The functional block diagram which shows the power generation system which concerns on other modification of 2nd Embodiment. The figure explaining the operation of the power generation system shown in FIG. The functional block diagram which shows the power generation system which concerns on 3rd Embodiment. The figure which shows the relationship of the displacement absolute value, the reference displacement and the impedance which concerns on 3rd Embodiment. The functional block diagram which shows the power generation system which concerns on the modification of 3rd Embodiment. The functional block diagram which shows the power generation system which concerns on 4th Embodiment. The figure which shows the relationship between the displacement absolute value and impedance which concerns on 4th Embodiment.

Hereinafter, embodiments will be described with reference to the drawings. Through the embodiments described below, the same components are designated by the same reference numerals, and the description thereof will be omitted. The drawings are schematic or conceptual.

[First Embodiment]
FIG. 1 is a functional block diagram showing a power generation system 1 according to the first embodiment. As shown in FIG. 1, the power generation system 1 includes a vibration power generator 10, a rectifying / smoothing circuit 20, a converter 30, a displacement measuring unit 40, a reference output unit 50, a comparator 60, a controller 70, and a pulse signal generation circuit 80. To prepare for.

The vibration power generator 10 converts vibration energy into AC power. The vibration power generator 10 is an example of a generator that converts mechanical energy into AC power, which is applicable to the power generation system 1.

The vibration power generator 10 will be described with reference to FIG. FIG. 2 is a cross-sectional view showing a structural example of the vibration power generator 10. As shown in FIG. 2, the vibration power generator 10 includes a case 11, a vibrator 12, a coil 13, a coil fixing member 14, and an elastic member 15.

The oscillator 12 is fixed to the elastic member 15 and suspended in the case 11. The oscillator 12 has magnets 12a, 12b, 12c and yokes 12f, 12g, 12h. The yoke 12f has a hollow substantially cylindrical shape and surrounds the magnets 12a, 12b, 12c and the yokes 12g, 12h. The upper center of the yoke 12f is connected to the elastic member 15. The magnet 12a, the yoke 12g, the magnet 12b, and the yoke 12h are sequentially arranged on the inner upper surface of the yoke 12f along the central axis thereof. The magnets 12a and 12b each have an N pole on the yoke 12g side. As a result, magnetic fluxes repelling each other are generated from each of the magnets 12a and 12b. The magnet 12c has, for example, a cylindrical shape, and is arranged on the inner surface of the yoke 12f at a distance from the outside of the coil 13. The magnet 12c has an S pole facing the coil 13 and an N pole in contact with the inner surface of the yoke 12f.

The coil 13 has an annular shape and is arranged outside the magnets 12a and 12b and inside the magnet 12c. The coil 13 is wound in the circumferential direction, and its central axis coincides with the central axis of the oscillator 12 (case 11).

The coil fixing member 14 fixes the coil 13 inside the vibrator 12. The coil fixing member 14 has a columnar coil support portion 14a fixed to the bottom surface of the case 11. The coil fixing member 14 is fixed to the case 11 by the coil support portion 14a, and is not fixed to the oscillator 12 (magnets 12a to 12c and yokes 12g, 12h).

The elastic member 15 has a disk shape, its side surface is fixed to the inner side surface of the case 11, and a part of the lower surface thereof is connected to the vibrator 12.

When external vibration is applied to the vibration power generator 10 having the above-mentioned structure, the coil 13 vibrates integrally with the case 11. The vibrator 12 vibrates with respect to the coil 13 at a predetermined frequency according to the elastic force of the elastic member 15. As a result, the oscillator 12 moves relative to the coil 13 in the axial direction, and the magnetic flux interlinking the coil 13 changes with time. Therefore, an electromotive force is generated by electromagnetic induction.

As described above, the external vibration (mechanical energy) applied to the vibration power generator 10 is converted into AC power. In the example shown in FIG. 2, magnets 12a, 12b, 12c and yokes 12f, 12g, 12h are arranged on the oscillator 12 corresponding to the movable portion, and the coil 13 is arranged on the case 11 corresponding to the stationary portion. Alternatively, the coil 13 may be arranged on the oscillator 12, and the magnets 12a, 12b, 12c and the yokes 12f, 12g, 12h may be arranged on the case 11. Further, although the vibration power generator 10 directly converts the vibration (movement in the vertical direction in the drawing) into AC power, it may be converted into AC power after converting the vibration into rotational movement.

Returning to FIG. 1, the rectifying / smoothing circuit 20 converts the AC power output from the vibration power generator 10 into DC power and smoothes the DC power. The rectifying / smoothing circuit 20 includes, for example, a rectifying circuit and a smoothing circuit. The rectifying circuit converts the AC power output from the vibration power generator 10 into DC power (usually pulsating current). The rectifier circuit includes, for example, one or more diodes. For example, a full-wave rectifier in which four diodes are bridge-connected can be used as a rectifier circuit. The smoothing circuit smoothes the DC power (pulsating current) output from the rectifier circuit. The smoothing circuit includes, for example, one or more capacitors, or a combination of capacitors and coils. The smoothing circuit smoothes the voltage by temporarily storing and releasing the current (pulsating current) as an electric charge. That is, the smoothing circuit is a kind of power storage circuit that stores electric power.

The converter 30 includes a switching circuit (also referred to as a switching element), and transforms the DC power output from the rectifying / smoothing circuit 20 based on the switching operation of the switching circuit. The switching circuit is driven by a pulse signal (square wave) from the pulse signal generation circuit 80. As the switching circuit, for example, a transistor or a MOSFET (metal-oxide semiconductor field-effect transistor) can be used. The electric power output from the converter 30 is appropriately supplied to an arbitrary device such as a sensor connected to the power generation system 1.

The converter 30 is, for example, a buck-boost converter. FIG. 3A shows an example of an electric circuit of a back boost converter. As shown in FIG. 3A, the backboost converter includes a capacitor 31, a switching circuit 32, a chopper coil 33, and a diode 34. The switching circuit 32 and the diode 34 are connected in series between the input terminal 35A and the output terminal 36A. One end of the capacitor 31 is connected to the connection point between the input terminal 35A and the switching circuit 32, and the other end is connected to the connection point between the input terminal 35B and the output terminal 36B. One end of the chopper coil 33 is connected to the connection point between the switching circuit 32 and the diode 34, and the other end is connected to the connection point between the input terminal 35B and the output terminal 36B. The switching circuit 32 is driven by a pulse signal as shown in FIG. 3B. The switching circuit 32 is turned on when the signal level of the pulse signal is high, and turned off when the signal level of the pulse signal is low.

The displacement measuring unit 40 measures the displacement of the movable portion (oscillator 12 in the example of FIG. 2) of the vibration power generator 10. As an example, the displacement measuring unit 40 measures the displacement of the movable portion of the vibration power generator 10 based on the electric signal output from the vibration power generator 10. A method of measuring the displacement of the movable part of the vibration power generator 10 based on the electric signal output from the vibration power generator 10 will be described later. The rectifier circuit is generally a non-linear element, and its influence becomes remarkable when the input voltage to the rectifier circuit is small. Therefore, preferably, a circuit for correcting the non-linearity of the rectifier circuit is provided in the displacement measuring unit 40.

In another example, the displacement measuring unit 40 measures the displacement of the movable portion of the vibration power generator 10 based on the output signal of the sensor provided in the vibration power generator 10. When the vibration generator 10 has the structure shown in FIG. 2, for example, an accelerometer is attached to the vibrator 12 or the elastic member 15, and the displacement measuring unit 40 integrates the acceleration measured by the accelerometer twice. Measure the displacement of the vibrator 12 with. Further, for example, a strainmeter is attached to the elastic member 15, and the displacement measuring unit 40 converts the strain of the elastic member 15 measured by the strainmeter into the displacement of the vibrator 12.

The displacement measurement method based on the electric signal output from the vibration power generator 10 can suppress the power consumption to be lower than the displacement measurement method using the sensor. Therefore, from the viewpoint of low power consumption, it is desirable to use a displacement measurement method based on an electric signal output from the vibration power generator 10. The displacement measuring unit 40 may be provided with a filter (for example, a high-pass filter or a low-pass filter) for removing noise. Further, a coil dedicated to displacement detection may be provided in the vibration power generator 10 separately from the coil for power generation, and displacement may be measured based on an electric signal output from the coil for displacement detection.

The reference output unit 50 sets (stores) a reference displacement (reference displacement) and outputs it to the comparator 60. The reference displacement is, for example, a limit value that defines an allowable range of displacement of the movable portion. In this embodiment, the reference displacement is a positive value. The reference displacement may be a negative value. Further, the reference output unit 50 may output two reference displacements, a positive reference displacement and a negative reference displacement. The reference output unit 50 may output a voltage corresponding to the reference displacement (hard output) or may output a signal representing the reference displacement (soft output).

The comparator 60 compares the displacement measured by the displacement measuring unit 40 with the reference displacement. The comparator 60 outputs a signal (hereinafter referred to as a trigger signal) to the controller 70 when the measured displacement becomes equal to or larger than the reference displacement. As the comparator 60, one having a hysteresis characteristic may be used.

The controller 70 controls the duty ratio of the switching circuit included in the converter 30. Specifically, the controller 70 increases the duty ratio when it receives a trigger signal from the comparator 60. For example, the controller 70 changes the duty ratio from the value D1 to a value D2 larger than the value D1. As an example, the duty ratio is changed by changing the period (Ton) in which the switching circuit is in the _ON state while maintaining the switching cycle (T _sw ). The controller 70 outputs a control signal indicating that the duty ratio has been changed to the pulse signal generation circuit 80. The controller 70 may have a refresh function for returning the duty ratio to the value D1 after a lapse of a preset time after changing the duty ratio to the value D2.

The pulse signal generation circuit 80 generates a pulse signal having a duty ratio controlled by the controller 70, and outputs this pulse signal to the converter 30.

The displacement measuring unit 40, the reference output unit 50, the comparator 60, the controller 70, and the pulse signal generation circuit 80 operate by the smoothing voltage output from the rectifying / smoothing circuit 20. Therefore, the power generation system 1 does not require a battery or the like. Further, the control unit that controls the duty ratio (in this embodiment, the portion including the displacement measuring unit 40, the reference output unit 50, the comparator 60, the controller 70, and the pulse signal generation circuit 80) is executed by hardware and a processor. It can be realized by the software to be used or a combination thereof. These points are the same for other embodiments.

Next, a method of measuring the displacement of the movable portion of the vibration power generator 10 based on the electric signal output from the vibration power generator 10 will be described.

ここで、ｘは可動部の変位を表し、Ｋは電圧定数を表し、Ｌ_ｃは振動発電機１０のコイル１３のインダクタンスを表し、Ｒ_ｃはコイル１３の抵抗を表し、Ｒ_ｌは、整流・平滑回路２０から見込む等価的な入力インピーダンス（整流・平滑回路２０、コンバータ３０及び発電システム１に接続される外部装置を含む）を表し、ｉは振動発電機１０の出力電流を表す。 FIG. 4 shows the electric circuit of the power generation system 1. The following equation holds for the electric circuit shown in FIG.

Here, x represents the displacement of the moving part, K represents the voltage constant, L _c represents the inductance of the coil 13 of the vibration generator 10, R _c represents the resistance of the coil 13, and R _l represents the rectification. It represents the equivalent input impedance expected from the smoothing circuit 20 (including the rectifying / smoothing circuit 20, the converter 30 and the external device connected to the power generation system 1), and i represents the output current of the vibration generator 10.

式２を変形すると、可動部の変位と電流の関係を示す下記の式３が得られる。

式３によれば、可動部の変位は、パラメータ（Ｋ、Ｌ_ｃ、Ｒ_ｃ、Ｒ_ｌ）の値、電流、及び電流の積分値から算出することができる。式３を使用した変位計測を行う場合、変位計測部４０は、振動発電機１０から出力される電流を検出する電流計、及び電流を積分する積分器を備える。この積分器は、アナログ回路で実現されてもよく、デジタル処理によって実現されてもよい。変位計測部４０は、電流計によって検出された電流と積分器によって得られた電流の積分値とに基づいて可動部の変位を算出する。 The Laplace transform of Equation 1 gives Equation 2 below.

By modifying Equation 2, the following Equation 3 showing the relationship between the displacement of the movable part and the current is obtained.

According to Equation 3, the displacement of the movable part can be calculated from the values of the parameters (K, L _c , R _c , R _l ), the current, and the integrated value of the current. When the displacement measurement using the equation 3 is performed, the displacement measurement unit 40 includes an ammeter for detecting the current output from the vibration power generator 10 and an integrator for integrating the current. This integrator may be realized by an analog circuit or may be realized by digital processing. The displacement measuring unit 40 calculates the displacement of the movable portion based on the integrated value of the current detected by the ammeter and the current obtained by the integrator.

式４によれば、可動部の変位は、パラメータ（Ｋ、Ｌ_ｃ、Ｒ_ｃ）の値、電流、電流の積分値、及び電圧の積分値から算出することができる。式４は、Ｒ_ｌが未知である場合に有効である。式４を使用した変位計測を行う場合、変位計測部４０は、振動発電機１０から出力される電流を検出する電流計、及び振動発電機１０から出力される電圧を検出する電圧計を備える。 Here, assuming that the input voltage to the electric circuit is _Vin , _Vin = R _l I, so Equation 3 is rewritten into Equation 4 below.

According to Equation 4, the displacement of the movable part can be calculated from the values of the parameters (K, L _c , R _c ), the current , the integrated value of the current, and the integrated value of the voltage. Equation 4 is valid when R _l is unknown. When the displacement measurement using the equation 4 is performed, the displacement measuring unit 40 includes an ammeter for detecting the current output from the vibration power generator 10 and a voltmeter for detecting the voltage output from the vibration power generator 10.

式５によれば、パラメータ（Ｋ、Ｌ_ｃ、Ｒ_ｃ、Ｒ_ｌ）の値、電圧、及び電圧の積分値から可動部の変位を算出することができる。式５を使用した変位計測を行う場合、変位計測部４０は、振動発電機１０から出力される電圧を検出する電圧計、及び電圧を積分する積分器を備える。この積分器は、アナログ回路で実現されてもよく、デジタル処理によって実現されてもよい。変位計測部４０は、電圧計によって検出された電圧と積分器によって得られた電圧の積分値とに基づいて可動部の変位を算出する。一般的に、電流を測定するよりも電圧を測定するほうが容易である。このため、式５を使用した変位計測は、式３又は式４を使用したものより有効である。ただし、式５を使用した変位計測では、Ｒ_ｌが既知である必要がある。 When all the current terms of the equation 4 are expressed by the voltage, the following equation 5 is obtained.

According to Equation 5, the displacement of the movable part can be calculated from the values of the parameters (K, L _c , R _c , R _l ), the voltage, and the integrated value of the voltage. When the displacement measurement using the equation 5 is performed, the displacement measurement unit 40 includes a voltmeter for detecting the voltage output from the vibration power generator 10 and an integrator for integrating the voltage. This integrator may be realized by an analog circuit or may be realized by digital processing. The displacement measuring unit 40 calculates the displacement of the movable unit based on the voltage detected by the voltmeter and the integrated value of the voltage obtained by the integrator. In general, it is easier to measure voltage than to measure current. Therefore, the displacement measurement using the formula 5 is more effective than the one using the formula 3 or the formula 4. However, in the displacement measurement using the equation 5, it is necessary that R _l is known.

If the first term of Equation 5 is negligibly small compared to the second term, the displacement of the movable part shall be calculated from the values of the parameters (K, R _c , R _l ) and the integrated value of the voltage. Can be done.

ここで、図３Ａ及び図３Ｂに示されるように、Ｔ_ｓｗはスイッチング周期を表し、Ｔ_ｏｎはスイッチング回路がオン状態にある期間を表し、Ｌ_ｄｃは出力用のチョッパコイルのインダクタンスを表し、Ｄはスイッチング回路（スイッチング動作）のデューティ比を表す。Ｄ＝Ｔ_ｏｎ／Ｔ_ｓｗである。 Here, when the converter 30 is a back boost converter as shown in FIG. 3A, R _l is expressed as in the formula 6.

Here, as shown in FIGS. 3A and 3B, T _sw represents the switching cycle, Ton represents the period during which the switching circuit is in the _ON state, L _dc represents the inductance of the chopper coil for output, and D. Represents the duty ratio of the switching circuit (switching operation). D = To _on / T _sw .

式７によれば、パラメータ（Ｋ、Ｌ_ｃ、Ｒ_ｃ、Ｌ_ｄｃ）の値、電圧、電圧の積分値、スイッチング周期Ｔ_ｓｗ、及びデューティ比Ｄから可動部の変位を算出することができる。 Substituting Equation 6 into Equation 5 yields Equation 7 below.

According to Equation 7, the displacement of the movable portion can be calculated from the values of the parameters (K, L _c , R _c , L _dc ), the voltage, the integrated value of the voltage, the switching period T _sw , and the duty ratio D.

式８によれば、Ｒ_ｌが未知である場合でも、パラメータ（Ｋ、Ｒ_ｃ、Ｌ_ｄｃ）の値、電圧の積分値、スイッチング周期Ｔ_ｓｗ、及びデューティ比Ｄから可動部の変位を算出することができる。 Here, when the first term of the equation 7 is negligibly small as compared with the second term, the equation 7 can be approximated as the following equation 8.

According to Equation 8, even when R _l is unknown, the displacement of the movable part is calculated from the values of the parameters (K, R _c , L _dc ), the integrated value of the voltage , the switching period T _sw , and the duty ratio D. can do.

Next, the operation of the power generation system 1 will be described.
FIG. 5 shows an operation procedure of the power generation system 1. The operation procedure shown in FIG. 5 starts when the power generation system 1 is started. For example, a start switch is arranged between the vibration power generator 10 and the rectification / smoothing circuit 20, and when this start switch is turned on, the power generation system 1 is started. The start switch may not be provided. In this case, it can be considered that the power generation system 1 is started when the vibration is applied to the power generation system 1. For example, when the power generation system 1 is installed in a vibration environment, or when the vibration is stopped for a certain period of time after the installation and then the vibration is restarted, it can be regarded as the start of the power generation system 1.

In step S101 of FIG. 5, the vibration power generator 10 receives environmental vibration to generate electricity. At the start of power generation, the input impedance R _l expected from the rectifying / smoothing circuit 20 may be set to an appropriate impedance Zr (that is, an impedance that maximizes the output power of the vibration power generator 10). Specifically, the duty ratio of the switching circuit included in the converter 30 may be set so that the input impedance R _l expected from the rectifying / smoothing circuit 20 becomes an appropriate impedance Zr.

In step S102, the displacement measuring unit 40 measures the displacement of the movable portion of the vibration power generator 10. For example, when the above equation 5 is used, the displacement measuring unit 40 measures the integrated value of the output voltage and the output voltage of the vibration power generator 10, and calculates the displacement of the movable portion based on the measured output voltage and the integrated value. .. The processing of steps S101 to S102 continues thereafter.

In step S103, the comparator 60 compares the measured displacement x with the reference displacement _xr . When the measured displacement x reaches the reference displacement _xr , the process proceeds to step S104. At this time, the comparator 60 outputs a trigger signal indicating that the measured displacement x is equal to or greater than the reference displacement _xr to the controller 70.

In step S104, the controller 70 increases the duty ratio of the switching circuit included in the converter 30 in response to receiving the trigger signal from the comparator 60. As a result, the input impedance R _l expected from the rectifying / smoothing circuit 20 decreases, and the current increases. Therefore, the braking force due to the current acting on the movable portion increases, and the displacement amplitude of the movable portion decreases.

FIG. 6 shows the time change of the displacement of the movable portion included in the vibration power generator 10. As shown in FIG. 6, when the input of the environmental vibration is started, the displacement amplitude of the movable portion gradually increases. When the displacement of the moving portion reaches the reference displacement xr, the duty ratio is increased, whereby the input impedance _{R l} expected from the rectifying / smoothing circuit 20 decreases from Zr to Za (Za <Zr). As a result, the displacement amplitude of the movable portion is suppressed. If the displacement of the movable portion reaches the reference displacement _xr again after the above-mentioned control, the duty ratio may be further increased.

As described above, in the power generation system 1 according to the first embodiment, when the displacement of the movable portion included in the vibration power generator 10 becomes equal to or more than the reference displacement, the duty ratio of the switching circuit included in the converter 30 is changed. Will be increased. As a result, the input impedance R _l expected from the rectifying / smoothing circuit 20 decreases, and the current easily flows. Therefore, the braking force due to the electric current acts strongly on the movable portion, and the displacement amplitude of the movable portion is suppressed. As a result, excessive displacement of the movable portion can be avoided. For example, it is possible to prevent the oscillator 12 from colliding with the case 11.

[Modified example of the first embodiment]
FIG. 7 shows a power generation system 1A according to a modified example of the first embodiment. As shown in FIG. 7, the power generation system 1A includes a vibration power generator 10, a rectifying / smoothing circuit 20, a converter 30, a displacement measuring unit 40, a reference output unit 50, a comparator 60, a controller 70, and a pulse signal generation circuit 80. And a power storage unit 90. The power generation system 1A is different from the power generation system 1 (FIG. 1) according to the first embodiment in that a power storage unit 90 is added.

The power storage unit 90 is provided after the converter 30. The power storage unit 90 includes, for example, one or more capacitors, a combination of capacitors and coils, or a secondary battery. The capacitor preferably has an initial voltage. For example, a lithium ion capacitor can be used. When the power storage unit 90 has a large capacity and an initial voltage, the output voltage is stable and the transient range of operation of the vibration power generator 10 is reduced. Therefore, the time to reach the stable range becomes faster. As a result, an increase in average power generation can be expected.

The power storage unit 90 may be provided in the power generation system according to each embodiment described later.

[Second Embodiment]
FIG. 8 shows the power generation system 2 according to the second embodiment. As shown in FIG. 8, the power generation system 2 includes a vibration power generator 10, a rectifying / smoothing circuit 20, a converter 30, a displacement measuring unit 40, an absolute value circuit 42, a reference output unit 50, a comparator 62, a controller 72, and A pulse signal generation circuit 80 is provided. The power generation system 2 relates to the first embodiment in that an absolute value circuit 42 is added, a comparator 60 is changed to a comparator 62, and a controller 70 is changed to a controller 72. It is different from the power generation system 1 (Fig. 1).

The absolute value circuit 42 calculates the absolute value of the displacement measured by the displacement measuring unit 40 (hereinafter, also referred to as the absolute displacement value). The absolute value circuit 42 may be realized by an analog circuit or may be realized by digital processing. The absolute value circuit 42 may have a general low-pass filter such as an RC (resistor-capacitor) filter or a peak hold function. When the absolute value circuit 42 includes a low-pass filter, the absolute displacement value is enveloped.

The comparator 62 compares the absolute displacement value measured by the displacement measuring unit 40 with the reference displacement. As an example, the comparator 62 outputs the first trigger signal to the controller 72 when the absolute displacement value becomes equal to or more than the reference displacement, and outputs the second trigger signal when the absolute displacement value becomes less than the reference displacement. Output to the controller 72. In another example, the comparator 62 does not output a signal while the absolute displacement is less than the reference displacement and outputs a signal while the absolute displacement is greater than or equal to the reference displacement. As the comparator 62, one having a hysteresis characteristic may be used.

The controller 72 controls the duty ratio of the switching circuit included in the converter 30 based on the output signal of the comparator 62. For example, the controller 72 adjusts the duty ratio to the value D1 when the absolute displacement value is less than the reference displacement, and adjusts the duty ratio to the value D2 (D2> D1) when the absolute displacement value is equal to or more than the reference displacement.

FIG. 9 shows the operation procedure of the power generation system 2. In step S201 of FIG. 9, the controller 72 sets the duty ratio of the switching circuit included in the converter 30 to the initial value D1. In step S202, the vibration power generator 10 receives environmental vibration to generate electricity. At the start of power generation, the absolute displacement value x _a is smaller than the reference displacement x _r . Therefore, the initial value of the duty ratio is set to the value D1. The value D1 is determined so that, for example, the input impedance R _l expected from the rectifying / smoothing circuit 20 becomes the appropriate impedance Zr.

In step S203, the displacement measuring unit 40 measures the displacement of the movable portion of the vibration power generator 10. In step S204, the absolute value circuit 42 calculates the absolute value of the displacement measured by the displacement measuring unit 40.

In step S205, the comparator 62 compares the absolute displacement value x _a with the reference displacement x _r . When the absolute displacement value x _a reaches the reference displacement x _r , the process proceeds to step S205.

In step S206, the controller 72 changes the duty ratio from the value D1 to the value D2. As a result, the input impedance R _l expected from the rectifying / smoothing circuit 20 decreases, and the current easily flows. Therefore, the braking force due to the current acting on the movable portion increases, and the displacement of the movable portion is suppressed.

In step S206, the comparator 62 compares the absolute displacement value x _a with the reference displacement x _r . When the absolute displacement value x _a is less than the reference displacement x _r , the process proceeds to step S207.

In step S207, the controller 72 changes (returns) the duty ratio from the value D2 to the value D1. As a result, the input impedance R _l expected from the rectifying / smoothing circuit 20 increases, and it becomes difficult for current to flow. Therefore, the braking force due to the current acting on the moving portion is reduced.

In this way, the duty ratio is set to the value D1 while the absolute displacement x _a is less than the reference displacement x _r , and the value D2 (D2>) while the absolute displacement x _a is greater than or equal to the reference displacement x _r . It is set to D1). In other words, as shown in FIGS. 10A and 10B, the impedance is set to the value Zr while the absolute displacement x _a is less than the reference displacement x _r , and the absolute displacement x _a is greater than or equal to the reference displacement x _r . In the meantime, the value is set to Za (Za <Zr).

As described above, in the power generation system 2 according to the second embodiment, the duty ratio is set to the value D1 during the period when the absolute displacement value x _a is less than the reference displacement x _r , and the absolute displacement value x _a is the reference displacement. The period of _xr or more is set to the value D2 (D2> D1). As a result, when the absolute displacement value x _a is equal to or greater than the reference displacement x _r , the input impedance R _l expected from the rectifying / smoothing circuit 20 decreases, and the current easily flows. Therefore, the braking force due to the electric current acts strongly on the movable portion, and the displacement of the movable portion is suppressed. As a result, excessive displacement of the movable portion can be avoided.

The threshold value used when changing the duty ratio from the value D1 to the value D2 may be different from the threshold value used when changing the duty ratio from the value D2 to the value D1. For example, the comparator 62 compares the absolute displacement value x _a with the reference displacement x _r2 in step S204, and compares the absolute displacement value x _a with the reference displacement x _r1 in step S206. Here, x _r2 > x _r1 .

[Modified example of the second embodiment]
Here, a case where the power generation system 2 performs displacement measurement based on the above-mentioned equation 7 will be described. In Equation 7, L _c , K, T, R _c , L _dc , and T _sw are constants, and D is a variable.

FIG. 11 shows a power generation system 2A according to a modified example of the second embodiment. In the power generation system 2A shown in FIG. 11, the displacement measuring unit 40 includes a voltmeter 401, an integrator 402, a displacement calculation unit 403, and an absolute value circuit 42.

The voltmeter 401 measures the output voltage of the vibration power generator 10. The integrator 402 integrates the output voltage of the vibration power generator 10.

The displacement calculation unit 403 holds the values D1 and D2 as the duty ratio D, and calculates the displacement of the movable unit according to the above equation 7. Specifically, the displacement calculation unit 403 is movable based on the voltage value output from the voltmeter 401, the voltage integral value output from the integrator 402, and the held duty ratio D1 or D2. Calculate the displacement of the part. The displacement calculation unit 403 includes, for example, an adder circuit, the voltage value output from the voltmeter multiplied by the coefficient of the first term of equation 7, and the voltage integrated value output from the integrator 402 with the second equation 7. Multiply by the coefficient of the term and add. The absolute value circuit 42 calculates the absolute value of the displacement calculated by the displacement calculation unit 403.

The reference output unit 50 outputs the two reference displacements x _r1 and x _r2 to the comparator 62. Here, x _r1 <x _r2 . The comparator 62 compares the absolute displacement value received from the absolute value circuit 42 with the reference displacements x _r1 and x _r2 . When the absolute displacement value reaches the reference displacement x _r2 while the duty ratio is set to the value D1, the controller 72 changes the duty ratio from the value D1 to the value D2. Further, when the absolute displacement value is less than the reference displacement x _r1 while the duty ratio is set to the value D2, the controller 72 changes the duty ratio from the value D2 to the value D1. In addition, x _r1 = x _r2 may be used.

The operation of the power generation system 2A will be described with reference to FIG. Here, the absolute value circuit 42 includes a low-pass filter, and an enveloped absolute value of displacement is obtained. When the power generation system 2A is started, the duty ratio is set to the value D1. At this time, the impedance is Z _High . Therefore, the absolute displacement value calculated based on the duty ratio D1 by the estimation circuit including the displacement calculation unit 403 and the absolute value circuit 42 is supplied to the comparator 62.

When the absolute displacement value gradually increases and reaches the reference displacement x _r2 (t = t1), the controller 72 changes the duty ratio from the value D1 to the value D2. As a result, the impedance becomes Z _Low (Z _Low <Z _High ). Therefore, the absolute displacement value calculated by the estimation circuit based on the duty ratio D2 is supplied to the comparator 62.

After that, when the absolute displacement value gradually decreases and falls below the reference displacement x _r1 (t = t2), the controller 72 changes the duty ratio from the value D2 to the value D1. As a result, the impedance becomes Z _High . As a result, the absolute displacement value calculated by the estimation circuit based on the duty ratio D1 is supplied to the comparator 62.

FIG. 13 shows a power generation system 2B according to another modification of the second embodiment. In the power generation system 2B shown in FIG. 13, the displacement measuring unit 40 includes a voltmeter 401, an integrator 402, and a displacement calculating unit 403. The displacement calculation unit 403 holds the value D1 as the duty ratio, and calculates the displacement of the movable unit according to the above equation 7. In the power generation system 2B, the absolute displacement value is calculated based on the value D1 not only during the period when the duty ratio is set to the value D1 but also during the period when the duty ratio is set to the value D2. As shown in FIG. 14, during the period when the duty ratio is set to the value D2, the absolute displacement value calculated using the value D1 is different from the absolute displacement value calculated using the value D2. In FIG. 14, the absolute displacement value calculated using the value D1 is shown by a solid line, and the absolute displacement value calculated using the value D2 is shown by a chain double-dashed line. Therefore, the reference displacement used when changing the duty ratio from the value D2 to the value D1 is the above-mentioned reference displacement x _r1 multiplied by the correction coefficient.

As described above, the displacement measuring unit 40 according to each modification of the second embodiment can measure the displacement of the movable unit based on the output voltage of the vibration power generator 10 without using an external sensor. As a result, the power required for displacement measurement can be reduced, and as a result, the power consumption of the entire system can be reduced.

[Third Embodiment]
FIG. 15 shows the power generation system 3 according to the third embodiment. As shown in FIG. 15, the power generation system 3 includes a vibration power generator 10, a rectifying / smoothing circuit 20, a converter 30, a displacement measuring unit 40, an absolute value circuit 42, a reference output unit 50, a difference measuring instrument 64, and a controller 74. And a pulse signal generation circuit 80. The power generation system 3 differs from the power generation system 1 (FIG. 1) according to the first embodiment in that the comparator 60 is changed to the difference measuring instrument 64 and the controller 70 is changed to the controller 74. .. Since the absolute value circuit 42 is the same as that described in the second embodiment, the description of the absolute value circuit 42 will be omitted.

The difference measuring instrument 64 calculates the difference between the absolute displacement value output from the absolute value circuit 42 and the reference displacement. The difference measuring instrument 64 includes, for example, a subtraction circuit, and obtains a difference obtained by subtracting a reference displacement from an absolute displacement value. The difference measuring instrument 64 may obtain a difference obtained by subtracting the absolute displacement value from the reference displacement.

The controller 74 controls the duty ratio based on the difference calculated by the difference measuring instrument 64. Specifically, the controller 74 sets the duty ratio to a preset value during the period when the difference is less than zero (that is, the absolute displacement is less than the reference displacement), and during the period when the difference is greater than or equal to zero. , Change the duty ratio so that the difference is zero. For example, the controller 74 increases the duty ratio as the difference is larger (that is, the absolute displacement value is larger). As a result, as shown in FIG. 16, when the absolute displacement value x _a is less than the reference displacement x _r , the impedance is set to the appropriate impedance Z r, and when the absolute displacement value x _a is greater than or equal to the reference displacement x _r , the impedance is set. The impedance is set so that the larger the difference, the smaller the impedance.

As the controller 74, for example, a general feedback control controller (for example, a P (proportional) controller, a PI (proportional-integral) controller, or a PID (proportional-integral-differential) controller) can be used. The controller 74 may have an offset in order to prevent the output of the control controller from becoming zero at the moment when the absolute displacement value becomes equal to the reference displacement.

As described above, in the power generation system 3 according to the third embodiment, when the difference between the absolute displacement value and the reference displacement is zero or more, the duty ratio is controlled so that the difference becomes zero. As a result, the same effect as that of the first embodiment can be obtained.

[Modified example of the third embodiment]
Here, a case where the power generation system 3 according to the third embodiment performs displacement measurement based on the above-mentioned equation 7 will be described.

FIG. 17 shows a power generation system 3A according to a modified example of the third embodiment. In the power generation system 3A shown in FIG. 17, the displacement measuring unit 40 includes a voltmeter 401, an integrator 402, a displacement calculating unit 403, and a duty ratio measuring circuit 409.

The voltmeter 401 measures the output voltage of the vibration power generator 10. The integrator 402 calculates the integrated value of the output voltage of the vibration power generator 10. The duty ratio measuring circuit 409 measures the duty ratio of the switching circuit. Specifically, the duty ratio measurement circuit 409 holds a switching cycle (T _sw ), and detects a period ( _Ton ) in which the signal level of the pulse signal output from the pulse signal generation circuit 80 is high. , The duty ratio is calculated by dividing the measured period by the switching cycle. The displacement calculation unit 403 displaces the movable portion based on the voltage measured by the voltmeter 401, the integrated value of the voltage obtained by the integrator 402, and the duty ratio measured by the duty ratio measuring circuit 409. Is calculated.

The duty ratio measuring circuit 409 may not be provided. In this case, the displacement calculation unit 403 receives information indicating the set value of the duty ratio from the controller 74, and calculates the displacement of the movable unit based on this information.

As described above, the displacement measuring unit 40 according to the modified example of the third embodiment can measure the displacement of the movable unit based on the output voltage of the vibration power generator 10 without using an external sensor. As a result, the power required for displacement measurement can be reduced, and as a result, the power consumption of the entire system can be reduced.

[Fourth Embodiment]
FIG. 18 shows the power generation system 4 according to the fourth embodiment. As shown in FIG. 18, the power generation system 4 includes a vibration power generator 10, a rectifying / smoothing circuit 20, a converter 30, a displacement measuring unit 40, an absolute value circuit 42, a reference output unit 50, a difference measuring instrument 64, and a controller 76. It includes a pulse signal generation circuit 80 and a power measurement unit 92. The power generation system 4 according to the fourth embodiment has the power generation system 3 according to the third embodiment (FIG. 15) in that the power measurement unit 92 is added and the controller 74 is changed to the controller 76. Different from.

When the environmental vibration is unsteady, the appropriate impedance Zr is not uniquely determined and changes from moment to moment. Therefore, if the duty ratio is fixed to the value D1 during the period when the absolute displacement value is less than the reference displacement as in the first to third embodiments described above, the power generation efficiency may decrease. In the present embodiment, the duty ratio is adaptively controlled so as to maximize the power during the period when the absolute displacement value is less than the reference displacement.

The power measuring unit 92 measures the output power of the vibration power generator 10. The controller 76 controls the duty ratio based on the electric power measured by the electric power measuring unit 92 during the period when the absolute displacement value is less than the reference displacement. For example, the controller 76 changes the duty ratio so as to maximize the output power of the vibration power generator 10. As a result, as shown in FIG. 19, the impedance changes according to the change in the duty ratio. As the power maximization algorithm, for example, a general method such as MPPT (Maximum Power Point Tracking Control) can be used. During the period when the absolute displacement value is equal to or greater than the reference displacement, the controller 76 controls the duty ratio so that the difference obtained by the difference measuring instrument 64 disappears, similarly to the controller 74 (FIG. 15) according to the third embodiment. do.

In the fourth embodiment, even when the environmental vibration is unsteady, it is possible to achieve both maximization of the generated power at the time of small vibration amplitude and suppression of displacement of the moving part at the time of large vibration amplitude.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and variations thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

1, 1A, 2, 2A, 2B, 3, 3A, 4 ... Power generation system,
10 ... Vibration power generator, 11 ... Case, 12 ... Oscillator, 12a, 12b, 12c ... Magnet,
12f, 12g, 12h ... yoke, 13 ... coil, 14 ... coil fixing member,
14a ... Coil support, 15 ... Elastic member,
20 ... Rectifier / smoothing circuit,
30 ... converter, 31 ... capacitor, 32 ... switching circuit,
33 ... Chopper coil, 34 ... Diode, 35A, 35B ... Input terminal,
36A, 36B ... Output terminal,
40 ... Displacement measuring unit, 42 ... Absolute value circuit, 401 ... Voltmeter,
402 ... Integrator, 403 ... Displacement calculation unit, 409 ... Duty ratio measurement circuit,
50 ... Reference output unit, 60, 62 ... Comparator, 64 ... Difference measuring instrument,
70, 72, 74, 76 ... controller, 80 ... pulse signal generation circuit,
90 ... power storage unit, 92 ... power measurement unit.

Claims (12)

A generator that includes a moving part and converts the mechanical energy of the moving part into single-phase AC power.
A displacement measuring unit that measures the displacement of the movable unit, and a displacement measuring unit.
An electric circuit connected to the generator and provided with a rectifying circuit that converts the single-phase alternating current power into direct current power and a converter that transforms the direct current power.
Equipped with
The converter comprises a switching circuit in which the duty ratio is controlled based on the measured displacement in order to set the input impedance of the electric circuit to a predetermined value.
The displacement measuring unit is a power generation system that measures the displacement of the movable portion based on the integrated value of the output voltage of the generator and the duty ratio . Further equipped with a comparator for comparing the measured displacement with the reference displacement,
The duty ratio is set to a first value when the measured displacement is less than the reference displacement, and the first value in response to the measured displacement being greater than or equal to the reference displacement. The power generation system according to claim 1, wherein the power generation system is set to a larger second value. An absolute value circuit that calculates the absolute value of the measured displacement,
A comparator that compares the calculated absolute value with the reference displacement,
Further prepare
The duty ratio is set to a first value when the calculated absolute value is less than the reference displacement, and is larger than the first value when the calculated absolute value is greater than or equal to the reference displacement. The power generation system according to claim 1, which is set to a second value. An absolute value circuit that calculates the absolute value of the measured displacement,
A comparator that compares the calculated absolute value with the first reference displacement and the second reference displacement larger than the first reference displacement.
Further prepare
The duty ratio is set to a second value in response to the calculated absolute value becoming greater than or equal to the second reference displacement, and the calculated absolute value is less than the first reference displacement. The power generation system according to claim 1, wherein the power generation system is set to a first value smaller than the second value in response to the above-mentioned second value. The power generation system according to any one of claims 2 to 4, wherein the first value is a value that sets the input impedance of the electric circuit to an impedance that maximizes the output power of the generator. An absolute value circuit that calculates the absolute value of the measured displacement,
A difference measuring instrument that measures the difference between the calculated absolute value and the reference displacement,
Further prepare
The power generation system according to claim 1, wherein the duty ratio is adjusted by P, PI or PID control so that the difference disappears. Further equipped with a power measuring unit for measuring the power of the single-phase AC,
The duty ratio is controlled based on the measured power when the calculated absolute value is less than the reference displacement, and the difference when the calculated absolute value is greater than or equal to the reference displacement. The power generation system according to claim 6, wherein the power generation system is adjusted so as to eliminate. One of claims 1 to 7, wherein the displacement measuring unit measures the displacement of the movable portion based on the output voltage of the generator, the integrated value of the output voltage, and the duty ratio. The power generation system described in. The power generation system according to any one of claims 1 to 8 , wherein the converter includes a back boost converter. The power generation system according to any one of claims 1 to 9 , further comprising a storage unit for storing the transformed electric power. The power generation system according to claim 10 , wherein the power storage unit includes a capacitor. The power generation system according to claim 10 , wherein the power storage unit includes a secondary battery.

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