CN103490764A - Scei interface circuit - Google Patents

Abstract

The invention discloses an SCEI interface circuit. The interface circuit can efficiently convert external mechanical vibration energy into electrical energy and store the electrical energy into an energy storage element. The electrical energy stored in the energy storage element can provide sufficient electrical energy for microelectronic devices to meet the requirements of the microelectronic devices for power supply. Compared with other interface circuits, the SCEI interface circuit has two obvious advantages that the recovery power of the SCEI interface circuit is larger than the maximum recovery power of the Parallel-SSHI interface circuit which has the largest recovery power in existing energy recovery interface circuits, the recovery power of the Parallel-SSHI interface circuit can change along with the load change, the recovery power of the interface circuit has no relation to loaders connected with the interface circuit, namely the recovery power of the interface circuit is optimal to any loader, and the characteristic that the recovery power of the interface circuit is optimal to any loader is especially important in actual application.

Description

The SCEI interface circuit

Technical field

The present invention relates to the Energy Recovery Technology based on piezoelectric effect, be specifically related to a kind of novel energy and reclaim interface circuit.

Background technology

Due to the progress of wireless technology and micro electro mechanical system (MEMS) technology, the power demands of the power supply unit of portable electric appts and wireless senser is also grown with each passing day, these equipment mostly be take lithium battery as main at present.Because the life-span is limit, lithium battery needs to change battery in use, but change battery under some occasion, is also the work that cost is very high and unrealistic.So, carry out new wireless energy supply technology research oneself become the task of top priority.Energy-recuperation system based on piezoelectric effect is that the mechanical vibrational energy that nature is extensively existed is converted to electric energy, this energy-recuperation system have power output large, electronic device is not produced to the advantages such as miniaturization that electromagnetic interference, volume are little, be easy to device.At present, the research work of the energy-recuperation system based on piezoelectric effect is at home and abroad all in the exploratory stage, still there are a large amount of theories and test problem to need to solve, the energy of highly effective reclaim interface circuit in current patent and document also seldom, common interface circuit have standard interface, SECE interface,

Parallel-SSHI interface, Series-SSHI interface.The standard interface circuit is simple and be easy to realize, but regenerative power is low and can change with load variations; The regenerative power of SECE interface circuit is four times of standard interface and can be with load variations in theory; The regenerative power of Parallel-SSH and Series-SSHI interface circuit is larger but can change with the variation of load than the SECE interface.These interface circuits still can not meet the needs of energy-recuperation system far away, still need constantly to research and develop the interface circuit of highly effective.

Therefore, need a kind of new technical scheme to address the above problem.

Summary of the invention

The invention discloses a kind of SCEI interface circuit, English full name is Synchronous Charge Extraction and Inversion Interface, i.e. piezoelectric energy recovery interface circuit.This interface circuit is compared with the existing interface circuit, and not only regenerative power is large and regenerative power does not change with load variations.

The SCEI interface circuit comprises following structure: by piezoelectric patches, inductance L ₁, electronic switch S ₁the L formed ₁c _poscillating circuit (1), the full-bridge rectification electric bridge D formed by four diodes ₁(2), by inductance L ₂, switch S ₂, sustained diode ₂, filter capacitor C _rthe voltage raising and reducing transducer (3) formed, extraneous load R _l(4); L ₁c _poscillating circuit (1) connects full-bridge rectification electric bridge D successively ₁(2), voltage raising and reducing transducer (3) and external load R _l(4).

The SCEI interface circuit carries out twice energy recovery within each mechanical oscillation cycle, and each energy reclaims and can be divided into Energy extraction, voltage upset, open circuit three phases.Changing in the maximum of mechanical vibration displacement Energy extraction, voltage upset, the open circuit three phases that minimum comprises in this half mechanical oscillation cycle is respectively:

(1) the Energy extraction stage: when mechanical vibration displacement reaches maximum, piezoelectric patches voltage V reaches maximum V _p, switch S ₂closure, now be stored in electric energy on piezoelectric patches to inductance L ₂shift, piezoelectric patches voltage V descends thereupon.When dropping to γ V _pthe time, switch S ₂disconnect, wherein γ is L ₁c _pthe upsetting ratio of oscillating circuit, 0<γ<1.Be transferred to inductance L ₂in electric energy pass through subsequently sustained diode ₂transfer to filter capacitor C _rwith load R _lin.

(2) the voltage upset stage: switch S ₂disconnect moment, switch S ₁closure, now inductance L ₁, switch S ₁, piezoelectric patches will form L ₁c _poscillation circuit.As half L ₁c _pafter finishing cycle of oscillation, switch S ₁disconnect, owing to there being energy loss, piezoelectric patches voltage V is by the γ V before vibration _pupset is the afterwards-γ that vibrates ²v _p.

(3) the open circuit stage: when above-mentioned switch S ₁after disconnection, the electric current I that piezoelectric patches flows out is zero, and after this along with vibration displacement, gradually to becoming large in the other direction, when mechanical vibration displacement reaches negative maximum, the voltage V of piezoelectric patches reaches negative maximum-V to piezoelectric patches voltage V _p, now half vibration period finishes.

Above-mentioned L ₁c _preverse circuit (1), is characterized in that inductance parameters L ₁should make L ₁c _pbe less than the cycle of oscillation of oscillating circuit the mechanical oscillation cycle 1/20 or less.In addition, should make inductance L ₁quality factor as far as possible greatly to reclaim more energy.Switch S ₁select the electronic switch of fast response time, low on-resistance.

Above-mentioned full-bridge rectification electric bridge D ₁(2), it is characterized in that diode selects the diode that switching speed is fast, forward conduction voltage drop is little, reverse cut-off current is little.

Above-mentioned voltage raising and reducing transducer (3), is characterized in that the switch S of this voltage raising and reducing transducer ₂should be when piezoelectric patches voltage V reaches extreme value closure, when piezoelectric patches voltage V drops to γ times of extreme value, disconnect, wherein γ is L ₁c _pthe upsetting ratio of oscillation circuit, 0<γ<1.In addition, should select the high-quality-factor inductance L ₂and make switch S ₂oN time be less than the vibration period 1/20 or less; Filter capacitor C _rcapacity should meet R _lc _rthis condition of 5T, wherein T is the mechanical oscillation cycle.

Beneficial effect of the present invention:

The present invention is that a kind of novel energy reclaims interface circuit, and this interface circuit has been compared two remarkable advantages with the existing interface circuit.At first the regenerative power that shows this interface circuit is greater than Parallel-SSHI interface circuit maximum regeneration power, and Parallel-SSHI interface circuit regenerative power maximum and regenerative power in current energy reclaims interface circuit but change with load variations.Next shows that the regenerative power of this interface circuit and load have nothing to do, and this characteristic is particularly important in actual applications.

The accompanying drawing explanation

Fig. 1 is the schematic diagram of SCEI interface circuit.

Fig. 2 is piezoelectric patches voltage oscillogram and the corresponding switch controlling signal of SCEI interface circuit.U in figure is mechanical vibration displacement, and V is piezoelectric patches voltage, s ₁and s ₂be respectively switch S ₁and S ₂control signal.

Fig. 3 is in constant exciting displacement situation, the regenerative power of standard interface, SECE, Series-SSHI, Parallel-SSHI and SCEI interface circuit-load R _ltheory relation figure.

Fig. 4 is the artificial circuit figure of SCEI interface circuit.

Fig. 5 is standard interface, SECE, Series-SSHI, Parallel-SSHI and the SCEI interface circuit regenerative power-load R that uses electronic simulation software Multisim to obtain _lthe simulation result of relation.

Embodiment

Below in conjunction with the drawings and specific embodiments, further illustrate the present invention, should understand these embodiment only is not used in and limits the scope of the invention for the present invention is described, after having read the present invention, those skilled in the art all fall within the application's claims limited range to the modification of the various equivalent form of values of the present invention.

Refer to shown in Fig. 1, the SCEI interface circuit comprises following structure: by piezoelectric patches, inductance L ₁, electronic switch S ₁the L formed ₁c _poscillating circuit (1), the full-bridge rectification electric bridge D formed by four diodes ₁(2), by inductance L ₂, switch S ₂, sustained diode ₂, filter capacitor C _rthe voltage raising and reducing transducer (3) formed, extraneous load R _l(4); L ₁c _poscillating circuit (1) connects full-bridge rectification electric bridge D successively ₁(2), voltage raising and reducing transducer (3) and external load R _l(4).

Above-mentioned L ₁c _preverse circuit (1), is characterized in that inductance parameters L ₁should make L ₁c _pbe less than the cycle of oscillation of oscillating circuit the mechanical oscillation cycle 1/20 or less.In addition, should make inductance L ₁quality factor as far as possible greatly to reclaim more energy.Switch S ₁select the electronic switch of fast response time, low on-resistance.

Above-mentioned full-bridge rectification electric bridge D ₁(2), it is characterized in that diode selects the diode that switching speed is fast, forward conduction voltage drop is little, reverse cut-off current is little.

Above-mentioned voltage raising and reducing transducer (3), is characterized in that the switch S of this voltage raising and reducing transducer ₂should be when piezoelectric patches voltage V reaches extreme value closure, when piezoelectric patches voltage V drops to γ times of extreme value, disconnect, wherein γ is L ₁c _pthe upsetting ratio of oscillation circuit, 0<γ<1.In addition, should select the high-quality-factor inductance L ₂and make switch S ₂oN time be less than the vibration period 1/20 or less; Filter capacitor C _rcapacity should meet R _lc _rthis condition of 5T, wherein T is the mechanical oscillation cycle.

Piezoelectric patches voltage waveform and corresponding switch controlling signal s during the work of SCEI interface circuit ₁, s ₂the visible Fig. 2 of state, this interface circuit carries out twice energy recovery within each mechanical oscillation cycle, each energy reclaims and can be divided into Energy extraction, voltage upset, open circuit three phases.The theory of below setting forth respectively this three phases and providing SCEI interface circuit regenerative power is derived, and what finally is interpreted as and at piezoelectric patches voltage V, drops to γ V _pshi KaiguanS ₂disconnect.

In the Energy extraction stage, when mechanical vibration displacement reaches maximum, piezoelectric patches voltage V reaches maximum V _p, switch S ₂closure, now be stored in electric energy on piezoelectric patches to inductance L ₂shift, piezoelectric patches voltage V descends thereupon, supposes that V drops to V _mthe time S ₂disconnect, now the electric energy on piezoelectric patches stops to L ₂shift, be transferred to inductance L ₂in electric energy will pass through sustained diode ₂transfer to filter capacitor C _rwith load R _lin.Therefore, the ENERGY E reclaimed in the Energy extraction stage _hfor:

$E_H=(\frac{1}{2}{C}_P{V}_P^2-\frac{1}{2}{C}_P{V}_M^2)\&CenterDot;\mathrm{\&eta;}$

C wherein _pfor the clamped capacitance of piezoelectric patches, the efficiency that η is the voltage raising and reducing transducer.

Switch S ₂disconnect moment, switch S ₁closure, the SCEI circuit enters the voltage upset stage, through half L ₁c _ps after cycle of oscillation ₁disconnect, piezoelectric patches voltage V is by the V before vibration _mupset is the V after vibration _m, V _mand V _mcontrary sign.Owing to having energy loss, V _mabsolute value be less than V _mabsolute value.For this reason, introduce this concept of upsetting ratio γ, its expression formula is:

$\mathrm{\&gamma;}=-\frac{V_m}{V_M},(0<\mathrm{\&gamma;}<1)$

The pass that can be obtained piezoelectric patches voltage V and electric current I and vibration displacement u by the standard piezoelectric equation is:

I=αu&-C _PV&

The power factor that wherein α is piezoelectric patches, C _pclamped capacitance for piezoelectric patches.

After the voltage upset stage finishes, SCEI enters the open circuit stage, and piezoelectric patches voltage is along with vibration displacement becomes greatly gradually to negative direction, and when mechanical vibration displacement reaches negative maximum, the voltage V of piezoelectric patches reaches negative maximum-V _p.Due in the open circuit stage, the electric current that flows out piezoelectric patches is zero, and above formula becomes α u&=C _pv& , in the time-domain in open circuit stage, to its integration, can obtain:

$V_m+V_P=\frac{2\mathrm{\&alpha;}}{C_P}{U}_M$

Order:

V _M=x·V _P

Simultaneous is above variously can obtain the ENERGY E that piezoelectric patches reclaims within half vibration period _hfunction expression about x is:

$E_H=\frac{{2\mathrm{\&alpha;}}^2{U}_M^2}{C_P}\&CenterDot;\frac{1-x^2}{{(1-\mathrm{\&gamma;x})}^2}\&CenterDot;\mathrm{\&eta;}$

Owing to carrying out twice energy recovery in a vibration period, so the regenerative power P of SCEI interface circuit is:

$P=\frac{E_H}{T/2}=\frac{{2\mathrm{\&omega;\&alpha;}}^2{\mathrm{<figure-callout\; id="2"\; label="U\; M"\; filenames="HDA0000384071710000021.png"\; state="\{\{state\}\}">U</figure-callout>}}_M^{}}{\mathrm{\&pi;}{C}_P}\&CenterDot;\frac{1-x^2}{{(1-\mathrm{\&gamma;x})}^2}\&CenterDot;\mathrm{\&eta;}$

Wherein T is the mechanical oscillation cycle, and ω is the mechanical oscillation angular frequency, U _mamplitude for mechanical vibration displacement.

In constant exciting displacement situation, be also mechanical vibration displacement amplitude U _mwhile keeping constant, only having x in the regenerative power P expression formula of SCEI is variable, and there is maximum in this regenerative power P.Order

can try to achieve:

^x _opt ⁼γ

Maximum regeneration power P now _mAXfor:

$P_{\mathrm{MAX}}=\frac{{2\mathrm{\&omega;\&alpha;}}^2{\mathrm{<figure-callout\; id="2"\; label="U\; M"\; filenames="HDA0000384071710000021.png"\; state="\{\{state\}\}">U</figure-callout>}}_M^{}}{{\mathrm{\&pi;C}}_P(1-{\mathrm{\&gamma;}}^2)}\&CenterDot;\mathrm{\&eta;}$

From x _opt=γ can see, work as V _m=γ V _pthe time, also in the Energy extraction stage, when piezoelectric patches voltage from maximum V _pdrop to γ V _pshi KaiguanS ₂disconnect, now the regenerative power maximum of SCEI.From maximum regeneration power P _mAXthe regenerative power of the known SCEI interface circuit of expression formula and load resistance R _lit doesn't matter, is also that the SCEI regenerative power does not change with load variations.

Fig. 3 has provided standard interface, SECE, Series-SSHI, Parallel-SSHI and theoretical regenerative power and the load R of SCEI in constant exciting displacement situation when the efficiency eta of upsetting ratio γ=0.5, voltage raising and reducing transducer=0.8 _lgraph of a relation.For making these figures not be subject to the impact of energy-recuperation system self parameter, optimal load and maximum regeneration power have been carried out to normalized with respect to optimal load and the maximum regeneration power of standard interface respectively.

Below be given in the regenerative power simulation result of electronic simulation software Multisim Plays interface, SECE, Series-SSHI, Parallel-SSHI and SCEI interface circuit.

According to the people's such as G.K.Ottman theory, piezoelectric patches can be with the clamped capacitance C of a sinusoidal current source parallel piezoelectric sheet _pmean, the frequency of this sinusoidal current source is identical with the mechanical oscillation frequency, its amplitude I _m=2 π f α U _m, wherein f is the mechanical oscillation frequency, the power factor that α is piezoelectric patches, U _mfor the mechanical vibration displacement amplitude.In order to guarantee that five kinds of interface circuits meet constant exciting displacement condition, as long as being set, they there is identical current source amplitude I _mget final product.In artificial circuit, the clamped capacitance C of piezoelectric patches _p=50nF, mechanical oscillation frequency f=50Hz, current source amplitude I _m=100uA.The circuit simulation figure of SCEI interface circuit is shown in Fig. 4.The regenerative power of the standard interface finally obtained, SECE, Series-SSHI, Parallel-SSHI, SCEI interface circuit is about load R _lsimulation result see Fig. 5.

Claims (5)

1. a SCEI interface circuit, is characterized in that, comprising: by piezoelectric patches, inductance L ₁, switch S ₁the L formed ₁c _poscillating circuit (1), the full-bridge rectification electric bridge D formed by four diodes ₁(2), by inductance L ₂, switch S ₂, sustained diode ₂, filter capacitor C _rthe voltage raising and reducing transducer (3) formed, external load R _l(4); L ₁c _poscillating circuit (1) connects full-bridge rectification electric bridge D successively ₁(2), voltage raising and reducing transducer (3) and external load R _l(4).

2. SCEI interface circuit according to claim 1, it is characterized in that, completing twice energy within each mechanical oscillation cycle reclaims, each energy reclaims and is divided into Energy extraction, voltage upset, open circuit three phases, changes in the maximum of mechanical vibration displacement Energy extraction, voltage upset, the open circuit three phases that minimum comprises in this half mechanical oscillation cycle and is respectively:

(1) the Energy extraction stage: when mechanical vibration displacement reaches maximum, piezoelectric patches voltage V reaches maximum V _p, now control signal makes switch S ₂closure, be stored in electric energy on piezoelectric patches to inductance L ₂shift, piezoelectric patches voltage V descends thereupon; When dropping to γ V _pthe time, switch S ₂disconnect, wherein γ is L ₁c _pthe upsetting ratio of oscillating circuit, 0<γ<1; Be transferred to inductance L ₂in electric energy pass through subsequently sustained diode ₂transfer to filter capacitor C _rwith load R _lin;

(2) the voltage upset stage: switch S ₂disconnect moment, switch S ₁closure, now inductance L ₁, switch S ₁, piezoelectric patches will form L ₁c _poscillation circuit; After finishing half cycle of oscillation, switch S ₁disconnect, owing to there being energy loss, piezoelectric patches voltage V is by the γ V before vibration _pupset is the afterwards-γ that vibrates ²v _p;

(3) the open circuit stage: when above-mentioned switch S ₁after disconnection, the electric current I that piezoelectric patches flows out is zero, and after this piezoelectric patches voltage V is along with vibration displacement becomes large to negative direction gradually, and when mechanical vibration displacement reaches negative maximum, the voltage V of piezoelectric patches reaches negative maximum-V _p, now half vibration period finishes.

3. SCEI interface circuit according to claim 1, is characterized in that inductance L ₁parameter should make L ₁c _pbe less than the cycle of oscillation of oscillating circuit the mechanical oscillation cycle 1/20 or less; Switch S ₁select the electronic switch of fast response time, low on-resistance.

4. SCEI interface circuit according to claim 1, is characterized in that, rectifier bridge D ₁middle diode is selected the diode that switching speed is fast, forward conduction voltage drop is little, reverse cut-off current is little.

5. SCEI interface circuit according to claim 1, is characterized in that, the closure when switch S 2 of voltage raising and reducing transducer reaches extreme value at piezoelectric patches voltage V disconnects when piezoelectric patches voltage V drops to γ times of extreme value, and wherein γ is L ₁c _pthe upsetting ratio of oscillating circuit, 0<γ<1; Inductance L ₂select the high-quality-factor inductance and make switch S ₂oN time be less than the mechanical oscillation cycle 1/20 or less; Filter capacitor C _rcapacity should meet R _lc _rthis condition of 5T, wherein T is the mechanical oscillation cycle.

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