CN105006983A - Rectifier circuit for piezoelectric energy collectors - Google Patents

Abstract

The invention discloses a rectifier circuit for piezoelectric energy collectors to solve the problem that the energy consumption of an existing circuit is high and the efficiency of a piezoelectric energy collector is low when the rectifier voltage of the piezoelectric energy collector is greater than 2.5 V. The rectifier circuit comprises a full-wave rectifier bridge (2) and an active diode circuit (4), and further comprises a bias circuit (3). The output end of the full-wave rectifier bridge (2) is connected with the input ends of the active diode circuit (4) and the bias circuit (3). The output end of the bias circuit (3) is connected with the bias voltage end of a comparator in the active diode circuit (4). The output end of the active diode circuit (4) is connected with an energy storage capacitor C3. The rectifier circuit for piezoelectric energy collectors has the advantages of being low in power consumption, high in energy conversion efficiency, and capable of ensuring the energy demand of wireless sensor network node load.

Description

A kind of rectification circuit for piezoelectric energy gatherer

Technical field

The invention belongs to micro-energy collection technology field, be specifically related to a kind of rectification circuit for piezoelectric energy gatherer.

Background technology

At present, the conventional batteries supply power mode of wireless sensor node exists that stored energy is limited, the life-span is short, and periodic replacement battery can make cost significantly increase, and some occasions even may not realize the defects such as replacing.And in natural environment, be filled with a large amount of environmental energies, as solar energy, heat energy, wind energy, electromagnetic energy and vibrational energy etc., therefore based on environmental energy collection technique, transducer is utilized to convert different environmental energies to electric energy, carry out management efficiently through power management special circuit and regulate again, thus form a kind of novel non-maintaining, long-life self powered supply, meet wireless sensor node to power efficient, environmental protection, independent, lasting demand.Due to the form of energy that vibrational energy is a kind of extensive existence, be particularly extensively present in big machinery, the building structure such as automobile, aircraft, bridge, be therefore of universal significance and application prospect widely by piezoelectric energy focused ultrasound vibrational energy.

Compared with the energy harvester of traditional macrostructure size, MEMS piezoelectric energy gatherer has that volume is little, lightweight, power density is large, be convenient to the plurality of advantages such as integrated.But due to by the restriction of dimension volume, the total power output of MEMS piezoelectric energy gatherer is lower, and be generally uW level, output impedance is high, and output current is little only μ A level, can not directly power for follow-up wireless sensor node even load.

" An Input-Powered Active AC/DC Converter with Zero Standby Power for EnergyHarvesting Application (a kind of active AC/DC rectification circuit of self-powered being applicable to collection of energy zero stand-by power consumption) ", Yuan Rao, David P.Arnold, Energy Conversion Congress and Exposition (ECCE), 2010IEEE, 4441st ~ 4446 pages describe a kind of AC/DC rectification circuit being applicable to piezoelectric energy and collecting, full-wave rectifying circuit is directly connected with active diode circuit (Active Diode) by it.The AC conversion that energy harvester obtains by full-wave rectifying circuit is direct current, so that storage of electrical energy; Active diode circuit is made up of a comparator and a PMOS, and its effect is the flow direction controlling electric current, avoids electric current to pour in down a chimney to input from output.

This circuit Problems existing is: the bias voltage (bias voltage refers to the grid terminal voltage for generation of the NMOS tube of bias current in comparator) in active diode circuit is directly provided by the voltage after full-wave rectification, full-wave rectification bridge output voltage at below 2.5V time, active diode circuit energy consumption is less.But in more situation, the voltage of MEMS piezoelectric energy gatherer after full-wave rectification can reach 2.5V-5V, when bias voltage is higher than 2.5V, active diode circuit, by consuming larger energy, reduces the efficiency of piezoelectric energy gatherer.

Summary of the invention

For prior art Problems existing, technical problem to be solved by this invention is just to provide a kind of rectification circuit for piezoelectric energy gatherer, it, when piezoelectric energy gatherer commutating voltage is greater than 2.5V, can reduce the power consumption of circuit, improves the efficiency of energy harvester.

In order to solve the problems of the technologies described above, the present invention includes full-wave rectification bridge and active diode circuit, also comprise biasing circuit, the output of full-wave rectification bridge is connected to the input of source diode circuit and biasing circuit, the output of biasing circuit is connected with the biased electrical pressure side of comparator in source diode circuit, and the output of active diode circuit is connected to storage capacitor C3.

Bias voltage due to comparator in active diode circuit relies on biasing circuit to provide, the output voltage of biasing circuit is set to below 0.7V, this bias voltage value can make the NMOS field effect transistor in active diode circuit be operated in sub-threshold region, thus effectively reduce power consumption, and the power consumption of biasing circuit own is also very low, so circuit power consumption of the present invention is less, improve the efficiency of energy harvester.

Advantage of the present invention is: power consumption is less, and energy conversion efficiency is high, can ensure the energy requirement of wireless network sensing node load.

Accompanying drawing explanation

Accompanying drawing of the present invention is described as follows:

Fig. 1 is theory diagram of the present invention;

Fig. 2 is basic circuit diagram of the present invention.

In figure: 1. piezoelectric energy gatherer; 2. full-wave rectification bridge; 3. biasing circuit; 4. active diode circuit.

Embodiment

Below in conjunction with drawings and Examples, the invention will be further described:

As depicted in figs. 1 and 2, the present invention includes full-wave rectification bridge 2 and active diode circuit 4, also comprise biasing circuit 3, the output of full-wave rectification bridge 2 is connected to the input of source diode circuit 4 and biasing circuit 3, the output of biasing circuit 3 is connected with the biased electrical pressure side of comparator in source diode circuit 4, and the output of active diode circuit 4 is connected to storage capacitor C3.

The principle of work of the present invention is: the power delivery that piezoelectric energy gatherer 1 produces is to full-wave rectification bridge 2, after rectification by power delivery to low energy storage unit C1, low energy storage unit C1 provides power supply for biasing circuit 3, the voltage comparator that biasing circuit 3 is active diode circuit 4 provides stable bias voltage, now, the electric energy after rectification is delivered to high energy storage unit C3 by active diode circuit 4.The voltage of memory cell C3 is within the scope of 2.5V ~ 5V.

As shown in Figure 2, in biasing circuit 3, electric capacity C1 as low electricity memory cell, for biasing circuit 3 provides voltage.Diode D1, D2, D3 are that C1 reduces storage voltage as decompression tube, three diodes can make voltage reduce 2V, and (four pins can be drawn by three diode connection point places, according to collection of energy magnitude of voltage corresponding in practical application, unsettled or connect different pin, independence selects the number of diodes being connected into circuit to be 0,1,2 or 3, ensure that biasing circuit normally works), reduce the operating voltage of biasing circuit, thus ensure biasing circuit 3 lower power consumption, also reduce the output voltage of biasing circuit 3 simultaneously, be reduced to below 0.7V.This biasing circuit 3 comprises 8 metal-oxide-semiconductors, M2, M5, M8 are that PMOS forms current mirror, M1, M4 are that PMOS passes through to form start-up circuit to drain terminal Injection Current, M2, M6, M7 and M8 form negative feedback loop, M5, M7 and M8 form positive feedback loop, but the conjunction feedback loop that M2, M5, M6, M7 and M8 are formed is negative feedback, stablizing with holding circuit output voltage.

If M2, M5 leakage current generation current increment Delta I _m2with Δ I _m5, M2, M5 and M8 form current mirror, then have

I _M2＝GI _M5(1)

ΔI _M2＝GΔI _M5(2)

In formula, G is the breadth length ratio of M6 and M8

$G=\frac{{(W/L)}_{M5}}{{(W/L)}_{M2}}---\left(3\right)$

In formula, W, L are respectively width and the length of corresponding metal-oxide-semiconductor.

The small-signal increment of M2 leakage current has following relation

ΔI _M6＝ΔI _M2·R·g _mM6(4)

G in formula _mM6for the mutual conductance of M6 pipe, R is equivalent resistance between M2 drain terminal and ground, and has

R＝(V _TH+V _DSatM6)/I _M2(5)

$g_{m_{M6}}=\frac{2I_{M6}}{V_{DSatM6}}=\frac{2I_{M5}}{V_{DSatM6}}=\frac{2I_{M2}}{G\·V_{DSatM6}}---\left(6\right)$

(5) in formula, V _tHfor the threshold voltage of M6 pipe, V _dSatM6it is the drain-source saturation voltage of M6 pipe.

Formula (5) and (6) are substituted in (4) and can obtain

${\mathrm{\ΔI}}_{M6}=\frac{2}{G}\·{\mathrm{\ΔI}}_{M2}\·(\frac{V_{TH}}{V_{DSatM6}}+1)=2{\mathrm{\ΔI}}_{M5}\·(\frac{V_{TH}}{V_{DSatM6}}+1)>{\mathrm{\ΔI}}_{M5}---\left(7\right)$

Similarly, M7 and M8 also meets the relation of formula (7), i.e. Δ I _m7> Δ I _m8.

Formula (7) shows, the drain voltage of M6 and the gate voltage of M7 will reduce, thus the leakage current of M2, M5, M7 and M8 will reduce, and the conjunction feedback loop that therefore M2, M5, M6, M7 and M8 are formed is negative feedback.

For ensureing that biasing circuit 3 can by output voltage control at below 0.7V, the M3 in circuit uses diode fashion to be connected into circuit, produces larger M Ω level resistance, make the leakage current of M2 pipe maintain nA level together with R1.By the effect of M2 current mirror mirror image, make whole circuit to be operated in sub-threshold status, thus ensure that the output voltage of biasing circuit 3 is at below 0.7V.In figure, M6 pipe drain terminal voltage is bias voltage required in the present invention.

Biasing circuit points to the circuit that active diode circuit 4 provides below 0.7V bias voltage, except above-mentioned biasing circuit 3, biasing circuit also has: as in January, 2003, IEEE JOURNAL OF SOLID-STATECIRCUITS the 38th volume the 1st phase 151-154 page describes G.Giustolisi, " ALow-Voltage Low-Power Voltage Reference Based on Subthreshold MOSFETs (based on subthreshold value metal-oxide-semiconductor field effect transistor Low-voltage Low-power voltage reference) " of the people such as G.Palumbo; In October, 2009, IEEE JOURNAL OFSOLID-STATE CIRCUITS the 44th volume the 10th phase 465-474 page describes Ippei Akita, " A 0.6-V Dynamic Bias Filter With 89-dB Dynamic Range in 0.18-um CMOS (based on 0.6V dynamic bias filter in 0.18umCMOS technique 89dB dynamic range) " of the people such as Kazuyuki Wada; In February, 2011, IEEEJOURNAL OF SOLID-STATE CIRCUITS the 46th volume the 2nd phase 465-474 page describes LucaMagnelli, " A 2.6nW 0.45V Temperature-Compensated SubthresholdCMOS Voltage Reference (the 2.6nW 0.45V temperature-compensating subthreshold value cmos voltage benchmark) " of the people such as Felice Crupi.

As shown in Figure 2, active diode circuit 4 is made up of a comparator and a PMOS switch pipe M21.The effect of active diode circuit 4 is the flow directions controlling electric current, avoids electric current to pour in down a chimney to input from output.The comparator of active diode circuit 4 provides supply power voltage by its full-wave rectification bridge output voltage after diode D4 step-down, reduces power loss of comparator further with this; In comparator, the bias voltage of NMOS tube M13, M14 is provided by biasing circuit 3 simultaneously, this bias voltage makes M13 and M14 two NMOS tube be operated in sub-threshold region, ensureing the power consumption greatly reducing comparator while comparator has comparing function, thus the efficiency of Energy Transfer can drastically increased.The supply power voltage that diode D5 is used to reduce comparator second level circuit makes itself and first order supply power voltage match, and does not affect the comparison performance of comparator, and can play the effect reducing power consumption.

In active diode circuit 4, M9, M10 are differential pair tube, M11, M12 are the input signal that latch structure amplifies differential pair tube.M16 is as second level common source amplifier tube, and M15 is used as the input imbalance reducing comparator.M17, M18 and M19, M20 form two groups of inverters, the waveform that adjustment exports, and export square-wave signal control switch pipe M21 break-make.

Technique effect of the present invention:

Application EDA simulation technology, uses Cadence simulation software to verify circuit theory diagrams.When full-wave rectification 2 output voltage is respectively 2.5V, 3V, 4V and 5V, circuit and circuit of the present invention described in simulation context technology respectively, and the power consumption corresponding to counting circuit, simulation result is as shown in table 1.

Table 1

From table 1, circuit of the present invention is under the high voltage condition being greater than 2.5V, breach the limitation of circuit described in background technology, make rectification circuit overall power still in uW level, its extremely low power consumption considerably improves energy conversion efficiency in the application of piezoelectric energy gatherer.

Claims (1)

1. the rectification circuit for piezoelectric energy gatherer, comprise full-wave rectification bridge (2) and active diode circuit (4), it is characterized in that: also comprise biasing circuit (3), the output of full-wave rectification bridge (2) is connected to the input of source diode circuit (4) and biasing circuit (3), the output of biasing circuit (3) is connected with the biased electrical pressure side of comparator in source diode circuit (4), and the output of active diode circuit (4) is connected to storage capacitor C3.