WO2015022794A1 - 発電装置 - Google Patents
発電装置 Download PDFInfo
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- WO2015022794A1 WO2015022794A1 PCT/JP2014/063319 JP2014063319W WO2015022794A1 WO 2015022794 A1 WO2015022794 A1 WO 2015022794A1 JP 2014063319 W JP2014063319 W JP 2014063319W WO 2015022794 A1 WO2015022794 A1 WO 2015022794A1
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- voltage
- power generation
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- 238000010248 power generation Methods 0.000 claims description 83
- 238000006073 displacement reaction Methods 0.000 claims description 56
- 238000001514 detection method Methods 0.000 claims description 18
- 230000000694 effects Effects 0.000 description 25
- 239000003990 capacitor Substances 0.000 description 16
- 238000010586 diagram Methods 0.000 description 16
- 230000007423 decrease Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 238000003780 insertion Methods 0.000 description 3
- 230000037431 insertion Effects 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 230000004044 response Effects 0.000 description 3
- 230000006399 behavior Effects 0.000 description 2
- 238000003306 harvesting Methods 0.000 description 2
- 229910052451 lead zirconate titanate Inorganic materials 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- HFGPZNIAWCZYJU-UHFFFAOYSA-N lead zirconate titanate Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ti+4].[Zr+4].[Pb+2] HFGPZNIAWCZYJU-UHFFFAOYSA-N 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
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Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
- H02N2/00—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction
- H02N2/18—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing electrical output from mechanical input, e.g. generators
- H02N2/181—Circuits; Control arrangements or methods
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
- H02N2/00—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction
- H02N2/18—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing electrical output from mechanical input, e.g. generators
- H02N2/186—Vibration harvesters
- H02N2/188—Vibration harvesters adapted for resonant operation
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/30—Piezoelectric or electrostrictive devices with mechanical input and electrical output, e.g. functioning as generators or sensors
- H10N30/304—Beam type
- H10N30/306—Cantilevers
Definitions
- the present invention relates to a power generation device, and particularly to a power generation device including a piezoelectric body.
- a power generation device disclosed in Japanese Patent Application Laid-Open No. 2012-254005 includes a piezoelectric member formed of a piezoelectric material, a pair of electrodes provided on the piezoelectric member, and a deformable member that repeatedly deforms the piezoelectric member.
- Patent Document 2 Japanese Patent Application Laid-Open No. 2012-175712
- Patent Document 3 Japanese Patent Application Laid-Open No. 2012-105518
- Patent Document 4 Japanese Patent Application Laid-Open No. 2012-110143
- US Patent Application Publication No. 2010/0079034 Patent Document 5
- JP 2012-65533 A Patent Document 6
- Yogesh K Ramadass et al., “An Efficient Piezoelectric Energy Harvesting Interface Circuit Using. a Bias-Flip Rectifier and Shared Inductor, IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL 45, No.1, JANUARY 2010 (Non-Patent Document 1).
- JP 2012-254005 A JP 2012-175712 A JP 2012-105518 A JP 2012-110143 A US Patent Application Publication No. 2010/0079034 JP 2012-65533 A
- An object of the present invention is to obtain high power generation efficiency in a power generation device including a piezoelectric body.
- the power generation device includes a power generation unit that generates power by externally applied vibration.
- the power generation unit includes a piezoelectric body that is deformed by the vibration and generates a voltage corresponding to the deformation amount, and a pair of electrodes formed on the surface of the piezoelectric body.
- the power generation device further includes an inductor, a switch connected in series to the inductor, and a control circuit that controls the switch.
- the inductor is electrically connected in parallel to the pair of electrodes, and forms a resonance circuit with the capacitance component of the piezoelectric body.
- the control circuit includes a first control mode in which the switch is turned on in synchronization with a timing at which the voltage generated in the piezoelectric body takes an extreme value, and a second control mode in which the switch is turned off at the timing at which the voltage takes the extreme value. Control mode.
- the control circuit inserts the control in the second control mode during the control in the first control mode when the vibration frequency is the natural frequency of the power generation unit.
- the control circuit turns on the switch for a period that is an odd multiple of 1/2 of the resonance period of the resonance circuit.
- the power generation device further includes a rectifier circuit that is connected in parallel between the pair of electrodes and rectifies the voltage between the pair of electrodes, and a power storage unit that stores the voltage rectified by the rectifier circuit.
- the power generation device further includes a voltage detection unit that detects a voltage between the pair of electrodes.
- the control circuit inserts control in the second control mode when the amplitude of the voltage detected by the voltage detection unit falls below a predetermined reference value.
- the power generation device further includes a displacement detection unit that detects the displacement of the power generation unit.
- the control circuit inserts the control in the second control mode when the amplitude of the displacement detected by the displacement detection unit falls below a predetermined reference value.
- the power generation efficiency of the power generation device including the piezoelectric body can be increased.
- FIG. 1 It is a circuit diagram which shows roughly the structure of the electric power generating apparatus which concerns on Embodiment 1 of this invention. It is a perspective view which shows schematically the structure of the electric power generation part shown in FIG. It is an exploded view which shows schematically the structure of the electric power generation part shown in FIG. It is a figure for demonstrating a mode that the electric power generation part shown in FIG. 1 vibrates. It is a figure for demonstrating the switching control by the control circuit shown in FIG. It is a figure for demonstrating the resonance of the resonance circuit in the switching control shown in FIG. It is a figure which shows the frequency dependence of the amplitude of the displacement of a weight.
- FIG. 6 is a diagram for explaining switching control at a natural frequency of a power generation unit in the power generation device according to Embodiment 1 of the present invention.
- FIG. 1 is a circuit diagram schematically showing the configuration of the power generation apparatus according to Embodiment 1 of the present invention.
- FIG. 2A is a perspective view schematically showing a configuration of the power generation unit shown in FIG. 1.
- FIG. 2B is an exploded view schematically showing the configuration of the power generation unit shown in FIG. 1.
- FIG. 3 is a diagram for explaining how the power generation unit 1 shown in FIG. 1 vibrates.
- a power generation device 100 includes a power generation unit 1, an inductor L, a voltage detection unit 2, a control circuit 3, a switch SW, a rectifier circuit 4, a power storage unit 5, and an output. Terminals T1 and T2 and a displacement detector 6 are provided.
- the power generation unit 1 is provided on a vibration exciter 200 for applying vibration to the power generation unit 1.
- the power generation unit 1 generates power by vibration applied from the vibrator 200.
- the power generation unit 1 includes a piezoelectric element 11, a metal plate 12, a support unit 13, and a weight 14.
- the piezoelectric element 11 is, for example, a unimorph type piezoelectric element.
- a metal plate 12 is bonded to one surface of the piezoelectric body 111.
- the piezoelectric element 11 includes a piezoelectric body 111, an upper electrode 112, and a lower electrode 113.
- the piezoelectric body 111 is a piezoelectric material formed in a thin plate shape.
- the piezoelectric material for example, lead zirconate titanate (PZT), quartz (SiO 2 ), or zinc oxide (ZnO) can be used.
- PZT lead zirconate titanate
- quartz quartz
- ZnO zinc oxide
- the upper electrode 112 and the lower electrode 113 are formed on the surface of the piezoelectric body 111 so as to sandwich the piezoelectric body 111 therebetween.
- the upper electrode 112 and the lower electrode 113 correspond to a “pair of electrodes” according to the present invention.
- the piezoelectric element 11 has, for example, a cantilever structure (cantilever structure). That is, one end of the piezoelectric element 11 is a fixed end and is attached to the support portion 13. The support unit 13 is fixed on the vibrator 200. The other end of the piezoelectric element 11 is a free end to which a weight 14 is attached.
- a cantilever structure cantilever structure
- the vibration in the vertical direction (z direction) is applied to the power generation unit 1 by the vibrator 200 (indicated by an arrow AR1 in the figure).
- the weight 14 vibrates in the z direction (indicated by an arrow AR2 in the figure).
- the displacement of the weight 14 is represented by ⁇ z.
- the piezoelectric body 111 is deformed with the vibration of the weight 14.
- a voltage Vp corresponding to the deformation amount of the piezoelectric body 111 is generated between the upper electrode 112 and the lower electrode 113 due to the piezoelectric effect.
- the piezoelectric element 11 is represented by an equivalent circuit in which a voltage source V and a capacitor C are connected in parallel.
- the voltage source V generates a voltage Vp.
- the capacitor C corresponds to the capacitance component of the piezoelectric body 111.
- the piezoelectric element 11 is not limited to that represented by the above equivalent circuit.
- the inductor L is connected in parallel with the capacitor C.
- the capacitor C is electrically connected in parallel between the upper electrode 112 and the lower electrode 113.
- the inductor L constitutes the capacitor C and the LC resonance circuit.
- the voltage detector 2 is connected to the capacitor C in parallel.
- Voltage detector 2 includes, for example, an A / D converter (not shown).
- the voltage detector 2 detects the voltage Vsw between the upper electrode 112 and the lower electrode 113 and outputs the detected value of the voltage Vsw to the control circuit 3.
- the control circuit 3 is, for example, a microcomputer.
- the control circuit 3 outputs a conduction signal S to the switch SW based on the value of the voltage Vsw received from the voltage detection unit 2.
- the switch SW is connected in series with the inductor L.
- the switch SW is switched from the off state to the on state in response to the conduction signal S from the control circuit 3.
- the rectifier circuit 4 is connected to the capacitor C in parallel.
- the rectifier circuit 4 includes, for example, diodes D1 to D4 that form a bridge-type full-wave rectifier circuit.
- the voltage Vout rectified by the rectifier circuit 4 is output between the output terminals T1 and T2.
- the power storage unit 5 is connected in parallel between the output terminals T1 and T2.
- the power storage unit 5 stores the voltage rectified by the rectifier circuit 4.
- a known secondary battery, capacitor, or capacitor can be used for power storage unit 5.
- the displacement detector 6 is provided, for example, above the weight 14 in the z direction.
- the displacement detector 6 electrically or optically measures the displacement ⁇ z of the weight 14 and outputs the value of the displacement ⁇ z to the control circuit 3.
- notched portions can be provided in part of the upper electrode 112 and the lower electrode 113.
- the notched portion is electrically separated from the portion for generating power of the piezoelectric element 11.
- a voltage corresponding to the strain generated in the piezoelectric element 11 appears in the notch portion.
- a laser displacement meter may be used.
- FIG. 4 is a diagram for explaining switching control by the control circuit 3 shown in FIG. Referring to FIG. 4, the horizontal axis is a time axis. The time at which vibration is applied to the power generation unit 1 is set to 0. The vertical axis represents the voltage Vp, the conduction signal S, and the voltage Vsw.
- FIG. 5 is a diagram for explaining resonance of the resonance circuit in the switching control shown in FIG.
- a sine wave vibration is applied to the power generation unit 1.
- the voltage source V generates a sine wave voltage Vp.
- the vibration applied to the power generation unit 1 is not limited to a sine wave as long as the frequency is constant and has an extreme value, and may be a sawtooth wave, for example.
- the weight 14 is displaced in the positive z direction during the period from time 0 to time t1. That is, the piezoelectric element 11 is deformed in a direction in which the upper electrode 112 side of the piezoelectric body 111 becomes concave (see FIG. 5A). Due to the piezoelectric effect generated by the deformation of the piezoelectric body 111, a positive charge is stored on the surface of the piezoelectric body 111 on the upper electrode 112 side, and a negative charge is stored on the surface of the piezoelectric body 111 on the lower electrode 113 side. Therefore, the voltage of the capacitor C becomes positive (see FIG. 5B).
- the control circuit 3 receives the value of the voltage Vsw from the voltage detection unit 2.
- the control circuit 3 outputs the conduction signal S in synchronization with the timing at which the voltage Vsw takes the extreme value, that is, the timing at which the voltage Vp takes the extreme value.
- the switch SW switches from the off state to the on state. (See FIG. 5C).
- the inductor L and the capacitor C constitute an LC resonance circuit.
- the switch SW When the switch SW is turned on, the LC resonance circuit resonates, and the voltage applied to both ends of the capacitor C is inverted to alternately take a positive and negative state.
- the conduction signal S is output only during a period of 1 ⁇ 2 of the resonance period TLC of the LC resonance circuit.
- the period during which the conduction signal S is output may be a period that is an odd multiple of 1/2 of the resonance period TLC.
- This state is a state in which the electric charge stored on the upper electrode 112 side of the piezoelectric body 111 and the electric charge stored on the lower electrode 113 side are switched compared to the state immediately before the switch SW is turned on.
- charge inversion A phenomenon in which the charge distribution of the piezoelectric body 111 is inverted by switching control by the control circuit 3 is referred to as charge inversion in this specification.
- the amplitude of voltage Vsw before charge reversal at time t1 and the amplitude of voltage Vsw after charge reversal at time (t1 + TLC / 2) are ideally equal.
- the weight 14 is displaced in the negative z direction.
- the piezoelectric element 11 is deformed in a direction in which the lower electrode 113 side of the piezoelectric body 111 becomes concave (see FIG. 5G). Due to the piezoelectric effect caused by the deformation of the piezoelectric body 111, a new negative charge is stored on the surface of the piezoelectric body 111 on the upper electrode 112 side, and a new positive charge is stored on the surface of the piezoelectric body 111 on the lower electrode 113 side. (See FIG. 5H)). Thereby, the amplitude of the voltage Vsw at time t2 is larger than the amplitude of the voltage Vsw at time t1.
- the control circuit 3 outputs the conduction signal S in synchronization with the timing at which the voltage Vsw takes the minimum value.
- the effect of resonance of the LC resonance circuit in the period from time t2 to time (t2 + TLC / 2) is the same as the effect in the period from time t1 to time (t1 + TLC / 2), although the polarity of the charge is opposite. Therefore, detailed description will not be repeated.
- the amplitude of the voltage Vsw increases every half cycle of the vibration of the piezoelectric body 111.
- a voltage Vsw higher than the voltage Vp generated by the voltage source V can be obtained. Therefore, the voltage Vout can be increased as compared with the case where the switching control is not executed, so that the power generation amount of the power generation apparatus 100 can be increased.
- the increase in the amplitude of the voltage Vsw stops.
- the main causes are a loss due to the conduction resistance of the switch SW and a loss due to the internal resistance of the inductor L.
- the amplitude of the voltage Vsw when the increase stops is about 4 to 5 times the amplitude of the voltage Vsw at time t1.
- the resonance period TLC of the LC resonance circuit is sufficiently shorter than the period of vibration applied to the power generation unit 1. For this reason, for example, when the piezoelectric body 111 is deformed in a direction in which the upper electrode 112 side of the piezoelectric body 111 is concave, the piezoelectric body 111 is still concave on the upper electrode 112 side even after charge reversal. When the charge inversion occurs, a force is generated in the piezoelectric body 111 so as to deform the lower electrode 113 so as to be concave due to the inverse piezoelectric effect (see FIG. 5E). That is, the direction of this force is a direction that prevents the deformation of the piezoelectric body 111 due to vibration applied from the vibrator 200. Thus, the effect that the vibration of the power generation unit 1 is attenuated by the inverse piezoelectric effect is referred to as a braking effect by charge reversal in this specification.
- FIG. 6 is a diagram showing the frequency dependence of the amplitude of the displacement ⁇ z of the weight 14.
- the horizontal axis represents the frequency f of the vibration applied to the power generation unit 1.
- the vertical axis represents the amplitude of the displacement ⁇ z of the weight 14.
- the natural frequency f0 of the power generation unit 1 is, for example, 18 Hz.
- the frequency f is different from the natural frequency f0, for example, when the frequency f is 15 Hz, the amplitude of the displacement ⁇ z is 40 ⁇ m.
- the amplitude of the displacement ⁇ z is remarkably large when the frequency f of the vibration applied to the power generation unit 1 matches the natural frequency f0 of the power generation unit 1. Therefore, in order to obtain the maximum power generation amount, it may be desirable to apply a vibration having the natural frequency f0 to the power generation unit 1.
- the behavior of the voltage Vsw and the displacement ⁇ z of the weight 14 differs depending on whether the frequency f matches the natural frequency f0. to differ greatly.
- FIG. 7 is a diagram showing the voltage Vsw and the displacement ⁇ z of the weight 14 when the frequency f of the vibration applied to the power generation unit 1 is different from the natural frequency f0.
- FIG. 8 is a diagram illustrating the voltage Vsw and the displacement ⁇ z of the weight 14 when the frequency f of the vibration applied to the power generation unit 1 matches the natural frequency f0. 7 and 8, the horizontal axis is a time axis. The vertical axis represents voltage Vp, conduction signal S, voltage Vsw, and displacement ⁇ z.
- a 15 Hz sine wave vibration different from the natural frequency f0 is applied to the power generation unit 1.
- the voltage source V generates a sine wave voltage Vp of 15 Hz.
- the control circuit 3 outputs the conduction signal S in synchronization with the timing at which the voltage Vp takes an extreme value.
- the amplitude of the voltage Vsw is about three times the amplitude before the start of switching control.
- the amplitude of the voltage Vsw gradually increases for several cycles from the start of the switching control.
- the amplitude of the voltage Vsw is kept substantially constant.
- the amplitude of the displacement ⁇ z of the weight 14 hardly changes regardless of the presence or absence of switching control of the switch SW. From this result, it is understood that when the frequency f of the vibration applied to the power generation unit 1 is different from the natural frequency f0, the displacement ⁇ of the weight 14 is hardly affected by the braking effect due to charge reversal.
- the voltage source V generates a sine wave voltage Vp of 18 Hz.
- the amplitude of the voltage Vsw increases rapidly. However, after time t2, the amplitude of the voltage Vsw gradually decreases. After time t3, the amplitude of the voltage Vsw becomes substantially constant at about 1 ⁇ 2 of the amplitude before the start of the switching control.
- the amplitude of the displacement ⁇ z of the weight 14 gradually decreases after time t1.
- the amplitude of the displacement ⁇ z is significantly reduced to about 1/10 of the amplitude before the start of the switching control.
- the amount of charge generated by the piezoelectric body 111 is proportional to the amplitude of the displacement ⁇ z of the weight 14. For this reason, the piezoelectric body 111 in the resonance state generates Q times as much charge as that in the non-resonance state.
- the piezoelectric body 111 generates a Q-times force due to the inverse piezoelectric effect. Therefore, at the natural frequency f0, the influence of the braking effect due to the charge reversal on the displacement ⁇ is significantly larger than that at the frequency different from the natural frequency f0.
- FIG. 9 is a diagram showing the frequency dependence of the influence of the braking effect on the amplitude of the voltage Vsw.
- the horizontal axis indicates the frequency f of the vibration applied to the power generation unit 1.
- the vertical axis represents the amplitude of the voltage Vsw.
- the frequency region where the amplitude of the voltage Vsw with switching control is less than the amplitude with no switching control is a region of the natural frequency f0 ⁇ 2.5% in the present embodiment.
- FIG. 10 is a diagram showing the frequency dependence of the effect of the braking effect on the amplitude of the displacement ⁇ z of the weight 14.
- the horizontal axis indicates the frequency f of the vibration applied to the power generation unit 1.
- the vertical axis represents the amplitude of the displacement ⁇ z.
- the amplitude of the displacement ⁇ z with switching control is less than the amplitude with no switching control in the frequency range of the natural frequency f0 ⁇ 15%.
- the frequency having a large influence of the braking effect due to the charge reversal extends over a frequency range of a certain extent around the natural frequency f0.
- ⁇ Switching control at natural frequency> Referring to FIG. 8 again, even when the vibration of the natural frequency f0 is applied to the power generation unit 1, the voltage Vsw increases for a certain period (period from time t1 to time t2) after switching control is started. ing. In the present embodiment, the control circuit 3 performs switching control using this property.
- FIG. 11 is a diagram for explaining switching control at the natural frequency f0 of the power generation unit 1 in the power generation apparatus 100 according to Embodiment 1 of the present invention. Referring to FIG. 11, FIG. 11 is compared with FIG.
- the control circuit 3 has a drive mode (first control mode) and a pause mode (second control mode) as modes for controlling the switch SW.
- the drive mode the control circuit 3 outputs the conduction signal S in synchronization with the timing at which the voltage Vp generated in the piezoelectric body 111 takes an extreme value.
- the switch SW is turned on.
- the pause mode the control circuit does not output the conduction signal S at the timing when the voltage Vp takes an extreme value. That is, the switch SW is turned off during the pause mode.
- the period from time 0 to time t1 is a period before the start of switching control by the control circuit 3. At time t1, the control circuit 3 starts switching control.
- control circuit 3 controls the switch SW according to the driving mode in a period from the time t1 to a time t4 when three times the period T0 (3T0) has elapsed.
- the switch SW is controlled in accordance with the sleep mode in a period from time t4 to time t5 after the elapse of the period T0 from time t4. In other words, the insertion of the control in the pause mode is started during the control in the drive mode.
- the control circuit 3 controls the switch SW in accordance with the drive mode in a period from the time t5 to the time t6 when the cycle T0 has elapsed.
- the control circuit 3 controls the switch SW according to the sleep mode in a period from the time t6 to the time t7 when the period T0 has elapsed. That is, the control circuit 3 inserts the control in the pause mode during the control in the drive mode. Since the switching control by the control circuit 3 after time t7 is equivalent to the switching control in the period from time t5 to time t7, description thereof will not be repeated.
- control circuit 3 alternately repeats the drive mode having a length corresponding to the period T0 of vibration applied to the power generation unit 1 and the pause mode having a length corresponding to the period T0.
- control circuit 3 may execute the switching control regardless of whether or not the detected value of the voltage Vsw is lower than the reference value V1. In this case, the control circuit 3 alternately repeats the drive mode and the pause mode immediately after the start of the switching control at time t1.
- control circuit 3 may start insertion of the pause mode when the amplitude of the displacement ⁇ z of the weight 14 detected by the displacement detection unit 6 falls below a predetermined reference value z1.
- the amplitude of the voltage Vsw is larger than the amplitude before the start of the switching control for several cycles immediately after the start of the switching control.
- a certain amount of time is required from the start of the switching control until the amplitude of the voltage Vsw starts to decrease.
- the control circuit 3 inserts the control in the pause mode before the amplitude of the voltage Vsw starts to decrease. Therefore, the amplitude of the voltage Vsw can be made larger than when switching control is not executed.
- the control circuit 3 inserts the control in the pause mode before the amplitude of the displacement ⁇ z is significantly reduced. Thereby, it is possible to prevent the amplitude of the displacement ⁇ z from being significantly reduced and the power generation amount of the power generation apparatus 100 from being reduced. That is, the power generation efficiency of the power generation apparatus 100 can be increased.
- FIG. 12 is a diagram for describing switching control at the natural frequency f0 of the power generation unit 1 in the power generation device according to Embodiment 2 of the present invention. Referring to FIG. 12, FIG. 12 is compared with FIG. 8 and FIG. In addition, since the structure of the electric power generating apparatus which concerns on Embodiment 2 is equivalent to the structure of the electric power generating apparatus 100 (refer FIG. 1), detailed description is not repeated.
- the control circuit 3 starts switching control.
- the detected value of the voltage Vsw at time t1 is lower than the reference value V1. Therefore, in a period from time t1 to time t2 when the period T0 has elapsed from time t1, the control circuit 3 controls the switch SW according to the drive mode.
- the control circuit 3 inserts the control in the pause mode during the control in the drive mode. Since the switching control by the control circuit 3 after time t3 is equivalent to the switching control in the period from time t1 to time t3, the description will not be repeated.
- control circuit 3 alternately repeats the drive mode having a length corresponding to the period T0 of vibration applied to the power generation unit 1 and the pause mode having a length corresponding to three times the period T0.
- control circuit 3 may execute the switching control regardless of whether or not the detected value of the voltage Vsw is lower than the reference value V1. Further, the control circuit 3 may start the insertion of the pause mode when the amplitude of the displacement ⁇ z of the weight 14 detected by the displacement detection unit 6 falls below a predetermined reference value z1.
- the amplitude of the voltage Vsw after the start of switching control is about twice the amplitude before the start of switching control.
- the amplitude of the displacement ⁇ z of the weight 14 after the start of switching control is about 2/3 of the amplitude before the start of switching.
- the amount of decrease in the amplitude of the displacement ⁇ z can be reduced to about 1/3 of the amplitude before the start of switching. Therefore, as in the first embodiment, it is possible to prevent the power generation amount of the power generator from decreasing. That is, the power generation efficiency of the power generation device can be increased.
- FIG. 13A is a diagram illustrating a condition for comparing electrostatic energy stored in the power storage unit illustrated in FIG. 1.
- FIG. 13B is a diagram for comparing electrostatic energy stored in the power storage unit illustrated in FIG. 1.
- the horizontal axis indicates the elapsed time from the start of storing energy in power storage unit 5.
- the vertical axis represents the electrostatic energy U stored in the power storage unit 5. Vibration of the natural frequency f0 is applied to the power generation unit 1.
- the waveform 13a represents the electrostatic energy U in the case where the driving period is always the switching control (see FIG. 8).
- a waveform 13b represents the electrostatic energy U in the first embodiment (see FIG. 11).
- a waveform 13c represents the electrostatic energy U in the second embodiment (see FIG. 12).
- a waveform 13d represents the electrostatic energy U when the switching control is not executed (or when the switching control is always stopped).
- the electrostatic energy U (see waveform 13a) in the case of the drive mode is about 60% when the switching control at the same time is not executed (see waveform 13d).
- the electrostatic energy U becomes smaller than the case where the switching control is not executed due to the braking effect due to the charge reversal.
- the electrostatic energy U (see waveform 13b) in the first embodiment is about 150% with respect to the same standard as described above. Further, the electrostatic energy U (see waveform 13c) in the second embodiment is about 180% with respect to the above standard.
- the electrostatic energy stored in the power storage unit 5 can be increased by inserting the control in the pause mode during the control in the drive mode.
- the lengths of the drive mode and the pause mode are not limited to the lengths described in the first and second embodiments.
- the length of each of the drive mode and the rest mode depends on the specifications of the power generation unit (for example, the method and structure of the piezoelectric element or the natural frequency of the power generation unit) or the conditions of the vibration applied to the power generation unit (for example, the magnitude of the amplitude). It is set as appropriate in consideration.
- the control circuit 3 may alternately repeat a one-cycle drive mode and a two-cycle pause mode.
- the control circuit 3 may alternately repeat the two-cycle drive mode and the two-cycle pause mode.
- the piezoelectric element 11 may be a bimorph type piezoelectric element, for example.
- the structure of the piezoelectric element is not particularly limited to the cantilever structure as long as the piezoelectric body is repeatedly deformed in response to periodic vibration.
- a piezoelectric body may be adhered to the surface of the thin film, or a piezoelectric body may be attached to the side surface of the string spring.
- control circuit 3 executes the switching control according to the driving period and the pause period of a predetermined length.
- the timing at which the control circuit 3 switches between the switching control drive period and the pause period is not limited to this.
- control circuit 3 may insert a pause mode only when the detected value of voltage Vsw falls below a predetermined reference value V1. Thereby, the amplitude of the weight 14 can be recovered.
- the control circuit 3 may insert the pause mode only when the amplitude of the displacement ⁇ z of the weight 14 detected by the displacement detection unit 6 falls below a predetermined reference value z1.
- 100 piezoelectric device 1 power generation unit, 11 piezoelectric element, 111 piezoelectric body, 112 upper electrode, 113 lower electrode, 12 metal plate, 13 support unit, 14 weight, V voltage source, C capacitor, 2 voltage detection unit, 3 control circuit , SW switch, L inductor, 4 rectifier circuit, D1 to D4 diode, 5 power storage unit, 6 displacement detection unit, T1, T2 output terminals.
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Abstract
Description
<発電装置の構成>
図1は、本発明の実施の形態1に係る発電装置の構成を概略的に示す回路図である。図2Aは、図1に示す発電部の構成を概略的に示す斜視図である。図2Bは、図1に示す発電部の構成を概略的に示す分解図である。図3は、図1に示す発電部1が振動する様子を説明するための図である。
図4は、図1に示す制御回路3によるスイッチング制御を説明するための図である。図4を参照して、横軸は時間軸である。発電部1に振動を加え始める時刻を0とする。縦軸は、電圧Vp、導通信号S、および電圧Vswを表す。図5は、図4に示すスイッチング制御における共振回路の共振を説明するための図である。
図6は、錘14の変位Δzの振幅の振動数依存性を示す図である。図6を参照して、横軸は発電部1に加えられる振動の振動数fを表す。縦軸は錘14の変位Δzの振幅を表す。
図8を再び参照すると、固有振動数f0の振動が発電部1に加えられる場合でも、電圧Vswは、スイッチング制御を開始してからある程度の期間(時刻t1以降、時刻t2までの期間)増加している。本実施の形態において、制御回路3は、この性質を利用してスイッチング制御を実行する。
図12は、本発明の実施の形態2に係る発電装置において、発電部1の固有振動数f0におけるスイッチング制御を説明するための図である。図12を参照して、図12は図8および図11と対比される。なお、実施の形態2に係る発電装置の構成は、発電装置100(図1参照)の構成と同等であるため、詳細な説明を繰り返さない。
Claims (5)
- 外部から加えられる振動によって発電する発電部を備え、
前記発電部は、
前記振動によって変形して、変形量に応じた電圧を発生させる圧電体と、
前記圧電体の表面に形成された一対の電極と、を含み、
前記一対の電極に並列に電気的に接続されて、前記圧電体の容量成分と共振回路を構成するインダクタと、
前記インダクタに直列に接続されたスイッチと、
前記スイッチを制御する制御回路と、をさらに備え、
前記制御回路は、前記圧電体に発生した電圧が極値を取るタイミングに同期して前記スイッチをオンの状態とする第1の制御モードと、前記極値を取るタイミングにおいて前記スイッチをオフの状態とする第2の制御モードとを有し、前記振動の振動数が前記発電部の固有振動数である場合に、前記第1の制御モードによる制御中に前記第2の制御モードによる制御を挿入する、発電装置。 - 前記制御回路は、前記第1の制御モードにおいて、前記共振回路の共振周期の1/2の奇数倍の期間、前記スイッチをオンの状態とする、請求項1に記載の発電装置。
- 前記一対の電極間に並列に接続され、前記一対の電極間の電圧を整流する整流回路と、
前記整流回路により整流された電圧を蓄える蓄電部と、をさらに備える、請求項1または2に記載の発電装置。 - 前記一対の電極間の電圧を検出する電圧検出部をさらに備え、
前記制御回路は、前記電圧検出部により検出された電圧の振幅が所定の基準値を下回った場合に、前記第2の制御モードによる制御を挿入する、請求項1~3のいずれか1項に記載の発電装置。 - 前記発電部の前記振動による変位を検出する変位検出部をさらに備え、
前記制御回路は、前記変位検出部により検出された変位の振幅が所定の基準値を下回った場合に、前記第2の制御モードによる制御を挿入する、請求項1~3のいずれか1項に記載の発電装置。
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CN201480043796.7A CN105556825B (zh) | 2013-08-13 | 2014-05-20 | 发电装置 |
JP2015531730A JP6027246B2 (ja) | 2013-08-13 | 2014-05-20 | 発電装置 |
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JP2017141948A (ja) * | 2016-02-10 | 2017-08-17 | テセラ・テクノロジー株式会社 | 振動吸収装置 |
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US20160156284A1 (en) | 2016-06-02 |
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EP3035521B1 (en) | 2018-08-29 |
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