CN102684549A - Adaptive active piezoelectric energy acquisition device - Google Patents

Abstract

The invention relates to an adaptive active piezoelectric energy acquisition device, which consists of a main circuit and a control unit thereof. A switching tube is connected in parallel with each diode of a full-bridge rectification unit. A direct current unit is a Buck circuit, and a switching tube of the Buck circuit is connected to the positive pole end of a charging capacitor. A current acquirer is arranged on the alternating current side of the full-bridge rectification unit. A power acquirer is arranged at the output end of the Buck circuit. An acceleration sensor for acquiring the frequency of external exciting force is also arranged in the main circuit. In order to adaptively obtain optimal control voltage, a power acquisition unit of a singlechip acquires an output power value in real time, and the optimal control voltage is adaptively regulated, so that the device works in a resonant state to maximally obtain mechanical energy, a damping period is shortened, the conversion power of the mechanical energy is improved, and impedance matching in realized in an electric energy transmission process to realize electric energy power output. When a system vibrates at frequency greatly deviated from fixed frequency, the energy acquisition power of the system cannot be greatly reduced.

Description

A kind of self adaptation is piezo-electricity energy harvester initiatively

Technical field

The present invention relates to the piezoelectric energy collection, promptly about being the technical field of electric energy with the ambient vibration power conversion, particularly a kind of self adaptation is piezo-electricity energy harvester initiatively.

Background technology

In recent years, along with improving constantly of MEMS, wireless sensor network and embedded system technology of preparing, traditional chemical cell can not satisfy people's demand, and it is the research of electric energy that people have begun power conversion in the surrounding environment.It can effectively solve because the problems such as pollution, energy consumption and maintenance of using battery to bring reduce cost greatly, improves people's living environment.

That piezo-electricity energy harvester has is simple in structure, do not have electromagnetic interference, be easy to the microminiaturization on processing and fabricating and the implementation structure, advantage such as integrated, by extensive concern.At present, the research of piezo-electricity energy harvester mainly concentrates on the form of the composition and system interface circuit two aspects of piezoelectric element.Improve the piezoelectric element form of the composition and mainly comprise change piezoelectric attribute, change the piezoelectric element mode of operation, utilize multiple stratification to increase and press the element dischargeable capacity, change the version of piezoelectric vibrator and the methods such as resonance frequency of regulating system.The system interface circuit has 3 kinds of working methods:

By braking technique, the system interface circuit generally is made up of a bridge rectifier and charging capacitor, and it is simple in structure, be easy to realize, but energy acquisition power is low.

Half active technique mainly comprises synchronous electric charge acquisition technique and inductance synchro switch acquisition technique.It can the Rapid Realization piezoelectric element electrodes overturn, and improves energy acquisition power, and with passive compared with techniques, peak power output can improve 4 times.

Active technique adopts equipment such as transducer, and active adjustment system resonance frequency has the better controlling effect, but system power dissipation is bigger, system complex.

Summary of the invention

The purpose of this invention is to provide initiatively piezo-electricity energy harvester of a kind of self adaptation, in order to solve conventional art when the disresonance frequence, the problem that energy acquisition power is low.

For realizing above-mentioned purpose; Scheme of the present invention is: a kind of self adaptation is piezo-electricity energy harvester initiatively; Constitute by main circuit and its control unit; Main circuit comprises the piezoelectric element that is used for the vibrational energy of outside exciting force is converted into electric energy, and piezoelectric element connects a full-bridge rectification unit that is made up of diode through inductance (L1) output, and the DC side of this full-bridge rectification unit connects an energy storage units through a DC/DC unit output; Also be provided with a charging capacitor (C1) between full-bridge rectification unit and the DC/DC unit; All be parallel with a switching tube (Q1-Q4) on each diode of said full-bridge rectification unit, said DC/DC unit is the Buck circuit, and the switching tube (Q5) in this Buck circuit is connected on the positive terminal of said charging capacitor (C1); The AC side of full-bridge rectification unit is provided with the current acquisition device, and the output of Buck circuit is provided with power harvester, also is provided with an acceleration transducer that is used to gather outside excitation force frequency in the main circuit; Said control unit input sample connects the power signal of the output signal of said acceleration transducer, said power harvester, the current signal of said current acquisition device; The control end of the paralleling switch pipe (Q1-Q4) of each diode of the said full-bridge rectification of said control unit output control connection unit, the switching tube (Q5) of said Buck circuit.

Said control unit comprises MCU; MCU produces the optimal voltage phase signal; The output signal of this optimal voltage phase signal, said acceleration transducer and the output signal of said current acquisition device are connected to a drive signal generation circuit as input, and this drive signal generation circuit output triggering signal is controlled the paralleling switch pipe (Q1-Q4) of each diode of said full-bridge rectification unit.

Said drive signal generation circuit is exported the control triggering signal of each switching tube (Q1-Q4) of the full-bridge rectification unit corresponding with vibration frequency through the output signal of the said acceleration transducer of input and the optimal control voltage phase signal of said MCU output.MCU produces the optimal voltage amplitude signal, and this optimal voltage amplitude signal outputs to the control end of the switching tube (Q5) of said Buck circuit.Said drive signal generation circuit also comprises and is used to the dead band generation unit of avoiding upper and lower bridge arm to open simultaneously.

Said MCU adopts the MSP430F169 microprocessor.Said current acquisition device is a current detecting unit, and this current detecting unit is through detecting the voltage difference detection electric current that string is located at the sampling resistor (Rsense1) of full-bridge rectification unit AC side.Said power harvester is a current acquisition unit, and this current acquisition unit is through detecting voltage difference collection electric current and/or the power that string is located at the sampling resistor (Rsense2) of DC/DC unit output.The paralleling switch pipe (Q1-Q4) of each diode of said full-bridge rectification unit, the switching tube (Q5) of said Buck circuit are MOSFET.Said energy storage units comprises a constant voltage charger, and this constant voltage charger output connects battery pack.

When ambient environment vibrations, the piezoelectric element on cantilever beam two surfaces converts vibrational energy into electric energy, and the equivalent electrical model of piezo-electricity energy harvester is as shown in Figure 3.Suppose extraneous exciting force for sinusoidal, then the impedance of mechanical part can be expressed as:

${\stackrel{\→}{Z}}_m=c+j(\mathrm{\ωm}-\frac{k}{\mathrm{\ω}}){\stackrel{\→}{Z}}_m---\left(1\right)$

In the formula, m, k, c, ω, α represent inertia mass, the rigidity of structure, damping coefficient, vibration frequency and the force factor of system respectively.

When mechanical part and the impedance matching of electricity part, system can collect ceiling capacity.The mechanical part matched impedance does

${\stackrel{\→}{Z}}_m=c+j(\frac{k}{\mathrm{\ω}}-m)---\left(2\right)$

To the electricity part, get the equivalence of mechanical part matched impedance

${\stackrel{\→}{Z}}_m=\frac{{\mathrm{\ω}}^{2}m-k+\mathrm{j\ωc}}{{\mathrm{\ω}}^2{c}_p-\mathrm{j\ω}({\mathrm{\ω}}^2{c}_{p}m-\mathrm{ck})}---\left(3\right)$

Wherein, c _pInternal capacitance for piezoelectric element.Can know that from (3) formula the matched impedance of electricity part is very complicated, be difficult for realizing, so we have designed a kind of active energy acquisition technique,, produced the impedance of equivalence through on piezo-electricity energy harvester, using a control voltage.

The conversion formula of piezoelectricity dynamical system is:

$I=-c_P\stackrel{\·}{U}-\mathrm{\α}\stackrel{\·}{\mathrm{\δ}}$

$F-\mathrm{\αU}=m\stackrel{\·\·}{\mathrm{\δ}}+c\stackrel{\·}{\mathrm{\δ}}+\mathrm{k\δ}---\left(4\right)$

Wherein, U, I are respectively the output voltage and the electric current of piezoelectric element, and F is outside exciting force, and δ is the displacement of piezo-electric device, after the displacement and speed of introducing piezo-electric device, after (4) formula conversion:

$\stackrel{\·}{\mathrm{\δ}}=V$

$\stackrel{\·}{V}=-\frac{k}{m}\mathrm{\δ}-\frac{c}{m}+\frac{1}{m}F+\frac{\mathrm{kd}}{m}V$

$\⇒$

$\left[\begin{array}{c}\stackrel{\·}{\mathrm{\δ}}\\ \stackrel{\·}{V}\end{array}\right]=\left[\begin{array}{cc}0& 1\\ -\frac{k}{m}& -\frac{c}{m}\end{array}\right]\left[\begin{array}{c}\mathrm{\δ}\\ V\end{array}\right]+\left[\begin{array}{c}0\\ \frac{1}{m}\end{array}\right]F+\left[\begin{array}{c}0\\ \frac{\mathrm{\α}}{m}\end{array}\right]U---\left(5\right)$

(5) formula shows that this system is controlled, so we can be provided with the characteristic value of this system arbitrarily, is negative value and enough big through the real part that characteristic value is set, and the mechanical oscillation of system are decayed fast, changes more electric energy.The output voltage of system as control voltage, is fed back to piezoelectric element.Under the exciting force F of constant amplitude effect, control voltage can be designated as:

U＝k _δδ+k _VV (6)

(6) formula substitution (5) formula, have:

$\left[\begin{array}{c}\stackrel{\·}{\mathrm{\δ}}\\ \stackrel{\·}{V}\end{array}\right]=\left[\begin{array}{cc}0& 1\\ \frac{k_{\mathrm{\δ}}\mathrm{\α}-k}{m}& \frac{k_V\mathrm{\α}-c}{m}\end{array}\right]\left[\begin{array}{c}\mathrm{\δ}\\ V\end{array}\right]+\left[\begin{array}{c}0\\ \frac{1}{m}\end{array}\right]F---\left(7\right)$

From (7) formula, displacement gain k _δCan change the natural frequency of piezoelectric system, rate gain can change the damping period of system, improves the transfer ratio of electric energy.When extraneous excitation force frequency constantly changes, k is set _δThe natural frequency that makes piezoelectric system is in real time near excitation force frequency, and then the acquisition ceiling capacity.The optimum natural frequency ω that system is new is:

$\mathrm{\ω}=\sqrt{\frac{k-k_{\mathrm{\δ}}\mathrm{\α}}{m}}---\left(8\right)$

The electric energy of piezo-electric device conversion depends on the product of voltage and speed, and under the control of feedback voltage, the electric energy of conversion is:

$W_{\mathrm{con}}=-\mathrm{\α}\∫U\stackrel{\·}{\mathrm{\δ}}\mathrm{dt}$

(9)

$=-\mathrm{\α}\∫(k_{\mathrm{\δ}}\mathrm{\δV}+k_V{V}^2)\mathrm{dt}$

Again because the phase difference of voltage and displacement is 90 °, so the integration of first of (9) formula is zero, promptly

W _con＝-αk _V∫V ²dt (10)

For compute optimal control voltage, need know optimum displacement gain k _δWith speed gain k _V, know from (4) formula:

$\stackrel{\→}{F}=(k-{\mathrm{\ω}}^{2}m+\mathrm{j\ωc})\stackrel{\→}{\mathrm{\δ}}-\mathrm{\α}\stackrel{\→}{U}$

(11)

$=(k-{\mathrm{\ω}}^{2}m-k_{\mathrm{\δ}}\mathrm{\α})\stackrel{\→}{\mathrm{\δ}}+(c-\mathrm{\α}{k}_V)\stackrel{\→}{V}$

When outside excited frequency matching system natural frequency, it is maximum that exterior mechanical can be converted into the efficient of electric energy, so optimum displacement gain k _δCan make system frequency mate outside exciting force, know from (7):

$k_{\mathrm{\δ}}=\frac{k-{\mathrm{\ω}}^{2}m}{\mathrm{\α}}---\left(12\right)$

Therefore, equality (11) becomes:

$\stackrel{\→}{F}=c\stackrel{\→}{V}-\mathrm{\α}{k}_V\stackrel{\→}{V}---\left(13\right)$

Simultaneously, (9) formula has provided optimal velocity gain K _VComputational methods, when extraneous exciting force F constant amplitude, W _ConMaximum, i.e. optimal velocity gain is:

$k_V=-\frac{c}{\mathrm{\α}}---\left(14\right)$

Therefore, make the maximum optimal control voltage of converting electrical energy be:

$\stackrel{\→}{U}=\frac{k-{\mathrm{\ω}}^{2}m}{\mathrm{\α}}\stackrel{\→}{\mathrm{\δ}}-\frac{c}{\mathrm{\α}}\stackrel{\→}{V}$

(15)

$=(\frac{k-{\mathrm{\ω}}^{2}m}{\mathrm{\α}}-\mathrm{j\ω}\frac{c}{\mathrm{\α}})\stackrel{\→}{\mathrm{\δ}}$

(15) formula substitution (10), optimal control voltage available external exciting force is expressed as:

${\stackrel{\→}{U}}_{\mathrm{opt}}=\frac{-\mathrm{\ωc}-j(k-{\mathrm{\ω}}^{2}m)}{2\mathrm{\α\ωc}}\stackrel{\→}{F}---\left(16\right)$

It is Fm that the case of external exciting force has a fixing amplitude, and then the amplitude of optimal control voltage is:

$U_{\mathrm{mag}}=\sqrt{{\mathrm{\ω}}^2{c}^2+{(k-{\mathrm{\ω}}^{2}m)}^2}\frac{F_m}{2\mathrm{\α\ωc}}---\left(17\right)$

When with reference to outside exciting force signal, the optimum angle difference between control voltage and outside exciting force is:

$\mathrm{\θ}=180-\arctan \left(\frac{k-{\mathrm{\ω}}^{2}m}{\mathrm{\ωc}}\right)---\left(18\right)$

Therefore,, always there is an optimal control voltage, makes energy acquisition power maximum for certain particular outer exciting force.

In order to obtain this optimal control voltage adaptively, the present invention gathers output power value in real time through single-chip microcomputer power collecting unit, according to self adaptation adjustment optimal control voltage; Make device be operated in resonance condition; Obtain the maximum machine ability, reduce damping period simultaneously, improve the transfer power of mechanical energy; Realize impedance matching in the electric energy transmitting process, output maximum power power.When system vibration during away from natural frequency, the energy acquisition power of system does not have very big reduction yet.Therefore, this device can improve system acquisition power in broad frequency range.

Description of drawings

Fig. 1 is a system block diagram of the present invention;

Fig. 2 is circuit theory diagrams of the present invention;

Fig. 3 is power conversion and coupling equivalent schematic diagram;

Fig. 4 is the output voltage wave figure of piezoelectric element;

Fig. 5 is a control flow chart;

Fig. 6 is the partial circuit in the drive signal generation circuit;

Fig. 7 is the oscillogram example of each node among Fig. 6.

Embodiment

Below in conjunction with accompanying drawing the present invention is done further detailed explanation.

A kind of self adaptation as shown in Figure 1 is piezo-electricity energy harvester initiatively; Constitute by main circuit and its control unit; Similar with prior art; Main circuit of the present invention comprises the piezoelectric element that is used for the vibrational energy of outside exciting force is converted into electric energy; Piezoelectric element connects a full-bridge rectification unit that is made up of diode through inductance L 1 output, and the DC side of this full-bridge rectification unit connects an energy storage units through a DC/DC unit output, also is provided with a charging capacitor C1 between full-bridge rectification unit and the DC/DC unit.

Main inventive point of the present invention is, on each diode of full-bridge rectification unit, all is parallel with a switching tube Q1-Q4, and the DC/DC unit is set to the Buck circuit, and the switching tube Q5 in this Buck circuit is connected on the positive terminal of said charging capacitor C1.Be similar to and initiatively gather the electric charge technology, Q5 generally is in cut-off state, and when the DC side of rectification unit reached certain value, the Q5 conducting was charged to the ability memory cell.And three input variables are depended in the control of Q1-Q4, and these three input variables are respectively: the amplitude of outside exciting force, the electric current of rectifier bridge AC side and charge power.In order to obtain this three input variables; Main circuit and control unit are carried out corresponding improvement: the AC side of full-bridge rectification unit is provided with the current acquisition device; The output of Buck circuit is provided with power harvester, also is provided with an acceleration transducer that is used to gather outside excitation force frequency in the main circuit; The control unit input sample connects the output signal of said acceleration transducer, the power signal of power harvester, the current signal of current acquisition device; The control end of the paralleling switch pipe Q1-Q4 of each diode of the said full-bridge rectification of control unit output control connection unit, the switching tube Q5 of Buck circuit.

Like Fig. 2; Provided a kind of concrete execution mode of Fig. 1 scheme; Control unit comprises MCU; MCU produces the optimal voltage phase signal, and the output signal of this optimal voltage phase signal, acceleration transducer and the output signal of current acquisition device are connected to a drive signal generation circuit as input, this drive signal generation circuit output triggering signal control switch pipe Q1-Q4.MCU produces the optimal voltage amplitude signal, and this optimal voltage amplitude signal outputs to the control end of the switching tube Q5 of Buck circuit.Drive signal generation circuit also comprises and is used to the dead band generation unit of avoiding upper and lower bridge arm to open simultaneously.

The current acquisition device is a current detecting unit, and this current detecting unit is through detecting the voltage difference detection electric current that string is located at the sampling resistor Rsense1 of rectification unit AC side.Power harvester is a current acquisition unit, and this current acquisition unit is through detecting voltage difference collection electric current and/or the power that string is located at the sampling resistor Rsense2 of DC/DC unit output.In this enforcement, energy storage units comprises a constant voltage charger, and this constant voltage charger output connects battery pack, so, can know charge power through sample rate current by a current acquisition unit.The paralleling switch pipe Q1-Q4 of each diode of full-bridge rectification unit, the switching tube Q5 of said Buck circuit are MOSFET.

Under this mode, control unit not only comprises MCU and peripheral circuit thereof, also comprises drive signal generation circuit, current detecting unit, power samples unit etc., and these element circuits are built by corresponding integrated or discrete device.In fact,, also can adopt MCU, above-mentioned three input variables are all imported MCU, directly export the triggering control signal by the MCU calculation process with corresponding function as other execution modes; The signal that current detecting unit, power samples unit are gathered, as long as keep the sampling resistor Rsense1 in the main circuit, Rsense2 also can directly be gathered by the MCU with AD function.Above-mentioned expansion is according to above embodiment, and those skilled in the art are easy to make, so no longer too much narration.

In the present embodiment, MCU adopts the MSP430F169 microprocessor.The MSP430F169 microprocessor adopts Low-power Technology, can be operated under 1.8V～3.6V voltage, normal mode of operation AM and 4 kinds of low power mode of operation LPM1, LPM2, LPM3, LPM4 is arranged, and can between various mode of operations, switch.In addition, the MSP430F169 single-chip microcomputer is integrated 60K program storage area, the data storage area of 2K, 8 tunnel quick 12 A/D converters, 12 D/A converters of two-way, two general continuous synchronization/asynchronous communication interfaces (USART), I ²C, DMA data transmitting module and 48 peripheral modules such as I/O mouth.

Below in conjunction with Fig. 2, above-mentioned three input variables (vibration frequency, ac-side current, dc output power) and two output variables (optimal control voltage phase signal and optimal control voltage magnitude signal, the i.e. triggering of Q1-Q5 control) are specified; These two output variables constitute the optimal control voltage that the summary of the invention part is discussed jointly, through controlling this two output variables, circuit are realized and the coupling of vibrating; Make device be operated in resonance condition; Obtain the maximum machine ability, reduce damping period simultaneously, improve the transfer power of mechanical energy; Realize impedance matching in the electric energy transmitting process, output maximum power power.And system vibration is during away from natural frequency, and the energy acquisition power of system does not have very big reduction yet.

The vibration frequency signal of drive signal generation circuit input acceleration transducer and the optimal control voltage phase signal of MCU; The vibration frequency signal is that the optimal control voltage phase signal of MCU output provides a reference time coordinate; Make the control triggering of Q1-Q4 corresponding, realize that commutation frequency is identical with vibration frequency with vibration frequency.The interlock circuit part is as shown in Figure 6, and the waveform of 1 to 6 node is shown in Fig. 7 (Fig. 7 has shown waveform or the sequential and their contrast of 1 to 6 node), and U9, U10 are comparator.Label 1 expression exciting force signal; Label 3 is the exciting force signal of an anti-phase; Label 2 expression optimal control voltage phase signals; Optimal control voltage and exciting force exist a phase difference

therefore to use exciting force as a reference during signal; With the optimal control voltage ratio after, producing phase difference is two square-wave signals of θ.Behind rest-set flip-flop,, make and produce the dead band time-delay between the signal again through the dead band production unit; Import signal again by current detecting unit output; Produce the triggering signal of final Q1-Q4, can be known by Fig. 2, current detecting unit is established a comparator U2 by a subtracter U1 string and is formed; Produce logical signal through comparator, this logical signal can influence the triggering signal of Q2, Q4.

The process of piezoelectricity conversion is following:

(1) external environment vibration, piezoelectric element produces AC energy through piezoelectric effect, and output line is transferred to the bridge rectifier unit through the two poles of the earth.

(2) rectification unit converts AC energy into direct current; To capacitor C 1 charging, when the voltage of capacitor C 1 reaches optimal control voltage, MOSFET pipe Q5 conducting; Electric energy transmitting is to energy storage units; If the voltage of capacitor C 1 is lower than optimal control voltage, MOSFET breaks off, and continues capacitor C 1 charging.

(3) simultaneously, 4 MOSFET pipe application of optimal in the full-bridge rectifier control voltage to piezoelectric element, improve the electric energy power output of device.As shown in Figure 4, the concrete course of work is: during state 1, Q2, Q3 break off, and Q1 is closed, and Q4 is influenced by the logical signal of current detecting unit output, and the big electric current that produces when regulating the upset of piezoelectric element two pole tensions reduces power consumption.During state 2, MOSFET Q1, Q4 are closed, and Q2, Q3 break off, and the piezoelectric element output voltage is for just, and size equals commutating voltage.During state 3, MOSFET Q1, Q3, Q4 closure, Q2 is influenced by the logical signal of current detecting unit output, reduces power consumption.State 1,2,3 o'clock, positive optimal control voltage acted on piezoelectric element, improved the electric energy power output.

During state 4, Q1, Q4 break off, and Q3 is closed, and Q2 is influenced by the logical signal of current detecting unit output.When state 5, Q2, Q3 closure, Q1, Q4 break off, and piezoelectric element is a negative voltage, and size equals commutating voltage.During state 6, Q1, Q2, Q3 closure, Q4 is influenced by the logical signal of current detecting unit output.State 4,5,6 o'clock, negative optimal control voltage acted on piezoelectric element, improved the electric energy power output.

(4) when the amplitude of vibration increased, sampled power increased, and corresponding optimal control voltage magnitude signal also increases, and vice versa; When vibration frequency greater than device during natural frequency; Sampled power reduces, and optimal control voltage magnitude signal increases, and the optimal control voltage phase signal increases; When vibration frequency less than device during natural frequency; Sampled power reduces, and optimal control voltage magnitude signal increases, and the optimal control voltage phase signal reduces.

As shown in Figure 5, the production process of optimal control voltage can be reduced to for 5 steps: wherein Ustep, θ step are preset increment size, and initial voltage obtains through correlation computations.Duty representes power, and Phase representes phase place.

The first step: MCU sets an initial control voltage, and its amplitude and phase place are designated as Um1 and θ 1 respectively, and the power of record rechargeable battery this moment is P1.

Second step: changing the control voltage magnitude is Um1+Ustep, phase invariant, and the power of record rechargeable battery is P2.

The 3rd step: if P2＞P1, then new control voltage magnitude is Um1+Ustep; If P2＜P1, then new control voltage magnitude is Um1-Ustep, and record performance number at this moment is P3.

The 4th one: the control voltage magnitude is constant, and changing the control voltage-phase is θ 1+ θ step, and record power at this moment is P4.

The 5th step: if P4＞P3, then new control voltage-phase is θ 1+ θ step; If P4＜P3, then new control voltage-phase are θ 1-θ step.

The above-mentioned steps that circulates successively just can produce optimal control voltage.And on long terms, can reach the effect described in the piezoelectricity transfer process.

Claims (10)

1. self adaptation piezo-electricity energy harvester initiatively; Constitute by main circuit and its control unit; Main circuit comprises the piezoelectric element that is used for the vibrational energy of outside exciting force is converted into electric energy; Piezoelectric element connects a full-bridge rectification unit that is made up of diode through inductance (L1) output, and the DC side of this full-bridge rectification unit connects an energy storage units through a DC/DC unit output, also is provided with a charging capacitor (C1) between full-bridge rectification unit and the DC/DC unit; It is characterized in that

All be parallel with a switching tube (Q1-Q4) on each diode of said full-bridge rectification unit, said DC/DC unit is the Buck circuit, and the switching tube (Q5) in this Buck circuit is connected on the positive terminal of said charging capacitor (C1); The AC side of full-bridge rectification unit is provided with the current acquisition device, and the output of Buck circuit is provided with power harvester, also is provided with an acceleration transducer that is used to gather outside excitation force frequency in the main circuit;

Said control unit input sample connects the power signal of the output signal of said acceleration transducer, said power harvester, the current signal of said current acquisition device; The control end of the paralleling switch pipe (Q1-Q4) of each diode of the said full-bridge rectification of said control unit output control connection unit, the switching tube (Q5) of said Buck circuit.

2. a kind of self adaptation according to claim 1 is piezo-electricity energy harvester initiatively; It is characterized in that; Said control unit comprises MCU; MCU produces the optimal voltage phase signal, and the output signal of this optimal voltage phase signal, said acceleration transducer and the output signal of said current acquisition device are connected to a drive signal generation circuit as input, and this drive signal generation circuit output triggering signal is controlled the paralleling switch pipe (Q1-Q4) of each diode of said full-bridge rectification unit.

3. a kind of self adaptation according to claim 2 is piezo-electricity energy harvester initiatively; It is characterized in that; Said drive signal generation circuit is exported the control triggering signal of each switching tube (Q1-Q4) of the full-bridge rectification unit corresponding with vibration frequency through the output signal of the said acceleration transducer of input and the optimal control voltage phase signal of said MCU output.

4. according to claim 2 or 3 described a kind of self adaptations active piezo-electricity energy harvesters, it is characterized in that MCU produces the optimal voltage amplitude signal, this optimal voltage amplitude signal outputs to the control end of the switching tube (Q5) of said Buck circuit.

5. a kind of self adaptation according to claim 2 is piezo-electricity energy harvester initiatively, it is characterized in that, said drive signal generation circuit also comprises and is used to the dead band generation unit of avoiding upper and lower bridge arm to open simultaneously.

6. a kind of self adaptation according to claim 2 is piezo-electricity energy harvester initiatively, it is characterized in that, said MCU adopts the MSP430F169 microprocessor.

7. a kind of self adaptation according to claim 1 is piezo-electricity energy harvester initiatively; It is characterized in that; Said current acquisition device is a current detecting unit, and this current detecting unit is through detecting the voltage difference detection electric current that string is located at the sampling resistor (Rsense1) of full-bridge rectification unit AC side.

8. a kind of self adaptation according to claim 1 is piezo-electricity energy harvester initiatively; It is characterized in that; Said power harvester is a current acquisition unit, and this current acquisition unit is through detecting voltage difference collection electric current and/or the power that string is located at the sampling resistor (Rsense2) of DC/DC unit output.

9. a kind of self adaptation according to claim 1 is piezo-electricity energy harvester initiatively, it is characterized in that the paralleling switch pipe (Q1-Q4) of each diode of said full-bridge rectification unit, the switching tube (Q5) of said Buck circuit are MOSFET.

10. a kind of self adaptation according to claim 1 is piezo-electricity energy harvester initiatively, it is characterized in that said energy storage units comprises a constant voltage charger, and this constant voltage charger output connects battery pack.

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