CN103596293A - Wireless sensor node stable power supply system based on minitype thermoelectric generator - Google Patents

Abstract

The invention discloses a wireless sensor node stable power supply system based on a minitype thermoelectric generator. A temperature difference electric energy collector is connected with a power supply management circuit, the power supply management circuit processes collected electric energy and transmits the electric energy to a load circuit composed of a temperature and humidity sensor, a microprocessor and a wireless communication module to provide electricity for the load circuit, and the microprocessor emits temperature and humidity data collected through the temperature and humidity sensor via the wireless communication module; the power supply management circuit comprises two parts, one part comprises a boost converter circuit having an MPPT function and an energy storage circuit, the other part comprises an energy buffer circuit, and the energy buffer circuit further comprises a double-voltage comparator circuit and a voltage stabilizer output circuit. The wireless sensor node stable power supply system improves efficiency of energy collection, does not waste weak temperature different energy in the environment, meanwhile can stabilize voltage with an adjustable output range, and prolongs the service life of a wireless sensor node without manual maintenance in poor environment regions.

Description

A kind of wireless sensor node stable power-supplying system based on miniature thermoelectric generator

Technical field

The present invention relates to electric power system field, particularly a kind of wireless sensor node stable power-supplying system based on miniature thermoelectric generator.

Background technology

The in the situation that of facing the serious problems such as energy scarcity, climate warming in the whole world, the mankind are for survival and development then remove to find and utilize clean energy technology.Clean energy resource comprises solar energy, wind energy, heat energy, vibrational energy, oceanic energy, and other energy are as body kinetic energy, biochemical energy homenergic.But these energy are dynamic changes, can not be directly by us, be utilized, we must utilize dynamic power acquisition technique by these dynamic stored energies in super capacitor or chemical cell, then just can be used.

Along with scientific and technological development, wireless sensor network technology has been penetrated into the every aspect of human being's production and life.Wireless communication networks progressively developed into can between anyone and object at any time, the Internet of Things of communication everywhere, the very fast expansion of scale of network, but meanwhile overall stability and the sustainable development of Internet of Things are also more and more outstanding.Although this is because the energy consumption of single wireless sensor node is not very large, but in Internet of things system, there is hundreds of millions of nodes, integrate and see that the total energy consumption of these nodes is very large, therefore can be stable for these sensor nodes, power and just determining that can Internet of things system sustainable development.Meanwhile, in order to meet human lives's needs, increasing transducer need to be placed in area uninhabited or that environment is severe, these regional rugged environments have determined that people cannot use chemical cell to power for wireless sensor node, because change chemical cells unlikely thing often in these areas.Just because of these reasons, people just expect adopting regenerative resource (the dynamically energy) to solve these problems for wireless communication node energy supply.The present invention is based on temperature difference energy acquisition in environment, by suitable energy management, finally supply with wireless sensor node.

Be compared to other environmental energy acquisition system, thermoelectric energy collecting system is to have special advantage.Thermoelectric cell is the temperature contrast of utilizing in environment, heat energy is converted into the device of electric energy.Be compared to solar cell homenergic and gather battery, a little less than the requirement relatively of thermoelectric cell for environment, can substantially be operated in any area in the world, be subject to the impact of weather little, for present thermal power transfer chip approximately as long as the temperature difference of 5 degrees Celsius just can wireless sensor network node of stabilized driving; Thermoelectric cell has especially unrivaled advantage in some special environment, and these available other environmental energies in area are very little, for example, we in daily life conventional it measure and smelt and the high temperature of heat-treatment furnace; The surface area of the cell panel of the collection luminous energy of solar cell is very large, cannot use in some miniature regions, as long as and have the enough large temperature difference and the thermo-electric converting material of efficiency necessarily, thermoelectric cell can be done very littlely and not affect its power output.

Traditional thermoelectric generator is applied to process industrial waste heat more, and the gross energy of these heats is very large, available thermal gradient energy is also very large, therefore at these local common thermoelectric generators, in conversion efficiency, also can reach very considerable output voltage be not very high in the situation that, these electric energy are finally realized grid-connected through certain energy management control appliance, realized the recycling of industrial waste heat.The feature of the thermoelectric generator system of traditional processing large scale industry used heat is as follows: (1) self thermoelectric couple very large, occupy very large space, and energy output is very large, but its absolute generating efficiency is lower.In addition, it involves great expense, and application scenario is very harsh, cannot be applied to wireless sensor network system.(2) technical grade thermoelectric generator system often needs to generate electricity by way of merging two or more grid systems, and needs complicated power transformation networking equipment, is widely used in the technical grades such as geothermal power generation for electrical domain, cannot adapt to the requirement of wireless sensor network system power supply.

Summary of the invention

The invention provides a kind of wireless sensor node stable power-supplying system based on miniature thermoelectric generator, the wireless sensor network that the present invention is based on miniature thermoelectric generator supply has been set up than more complete energy from the wireless sensor network system of supplying with, effectively solved the faint problem that is not enough to provide wireless sensor network node use of miniature thermoelectric generator energy output, described below:

A kind of wireless sensor node stable power-supplying system based on miniature thermoelectric generator, comprise: for collecting the temperature difference power collector of electric energy, described temperature difference power collector connects electric power management circuit, described electric power management circuit is processed rear stable transfer to the load circuit being comprised of Temperature Humidity Sensor, microprocessor and wireless communication module by the electric energy of collecting, for described load circuit power supply, the wet temp data that described microprocessor collects described Temperature Humidity Sensor are launched by described wireless communication module;

Wherein, described electric power management circuit is by two parts the electric circuit constitute, and first's circuit comprises: boost converter circuit and energy storage circuit; Second portion circuit is energy buffer circuit, and described energy buffer circuit comprises: two voltage comparator circuits and pressurizer output circuit.

Described boost converter circuit and energy storage circuit comprise: miniature thermoelectric generator TEG,

What described miniature thermoelectric generator TEG exported is the naked voltage of thermoelectric conversion, and described miniature thermoelectric generator TEG output is through resistance R ₁the VIN_DC end of access BQ25504 chip; Resistance R ₁through high frequency choke coil LBST access LBST end; Resistance R ₁capacitor C HVR ground connection after filtering; VIN_DC connects VOC_SAMP by resistance R oc2, and VOC_SAMP is by resistance R oc1 ground connection; VRDIV is by resistance R ov2 and resistance R ov1 ground connection; Between VRDIV and VBAT_OV, by resistance R ov2, be connected; VRDIV is by resistance R uv2 and resistance R uv1 ground connection; Between VBAT_UV and VRDIV, by resistance R uv2, be connected; VBAT_UV connecting resistance Ruv1 ground connection; VBAT_UV is by resistance R ok3, Rok2 and Rok1 ground connection; Between VBAT_UV and OK_HYST, by resistance R ok3, be connected; Between OK_HYST and OK_PRCG, by resistance R ok2, be connected; OK_PRCG is by resistance R ok1 ground connection; VSS and AVSS ground connection; VBAT meets energy storage capacitor Cstor by diode D1.

Described pair of voltage comparator circuit comprises: MIC841N chip,

The positive pole of the Vin termination energy storage capacitor Cstor of MIC841N chip; Vin end is held by resistance R 2 access LTH; LTH end is connected by resistance R 3 with HTH end; HTH terminating resistor R4 is ground connection then; Vout connects pressurizer output circuit.

Described pressurizer output circuit comprises: TPS78001 chip,

The positive pole of the IN termination energy storage capacitor Cstor of TPS78001 chip; EN enables the output of termination MIC841N chip; Connecting resistance R5 between OUT end and FB end; FB terminating resistor R6 is ground connection then; A stable voltage of OUT end output.

The beneficial effect of technical scheme provided by the invention is: the present invention passes through the combination of miniature thermoelectric generator and sensor node, make wireless sensor node there is no self-powered in battery powered situation, solve the energy bottleneck of wireless sensor network, in ruthless area, without manual maintenance, can extend the useful life of wireless sensor node.The present invention adopts up-to-date electric energy management chip and electrical energy storage, effective storage and utilization for faint thermal gradient energy have been realized, reached and can draw energy ，Wei China and providing certain reference value aspect miniature environment energy acquisition circuit from being low to moderate the ultralow energy of 80mv.In order more effectively to utilize miniature energy, the present invention has designed energy buffer, can when collecting energy is not enough, temporarily serve as the role in Power supply source, guarantees wireless sensor node steady operation.Simultaneously, the present invention utilizes energy buffer to solve cleverly a switching difficult problem that discharges and recharges operating state in energy acquisition management circuit for energy storage capacitor, do not use the complex controls such as single-chip microcomputer, rely on comparator and pressurizer to realize the control that energy storage capacitor is discharged and recharged, effectively saved energy consumption.Be wireless sensor network from the important component part of feed system, the communications industry of effectively having supported development ，Wei China of national green Energy Saving Industry technology to build " low-carbon (LC) " environmental protection during " 12 " has been made contribution.

Accompanying drawing explanation

Fig. 1 is the schematic diagram of the wireless sensor node stable power-supplying system based on miniature thermoelectric generator;

Fig. 2 is the schematic diagram of electric power management circuit;

Fig. 3 is with the DC-DC booster circuit of MPPT function and the schematic diagram of energy storage circuit principle;

Fig. 4 is the schematic diagram of the two voltage comparator work reference circuits of MIC841N;

Fig. 5 is MIC841N chip operation function diagram;

Fig. 6 is pressurizer output circuit schematic diagram.

Embodiment

For making the object, technical solutions and advantages of the present invention clearer, below in conjunction with accompanying drawing, embodiment of the present invention is described further in detail.

Regenerative resource power supply technology has more and more been widely used in the design of wireless sensor network node, yet the collection of regenerative resource is very difficult, the energy meanwhile producing is also extremely faint, therefore just need a kind of proposition of the system of using to energy from collecting energy, energy management, be used for making the stable work of whole sensor network to go down.Researchs at present both domestic and external mainly concentrate on the research of large-scale solar energy renewable energy source power or large-scale thermo-electric generation equipment and power transformation, seldom have research for the wireless sensor network of miniature thermoelectric generator power supply.The research many places of carrying out for miniature regenerative resource collection are at present in a kind of so awkward condition: want farthest from small energy source collecting energy, just must adopt energy acquisition and the administration module circuit of sophisticated, and often the power consumption of this part circuit is also very considerable, all in all, for whole energy collecting system, lose more than gain.The present invention is in order to address this problem, aspect two of energy acquisition and energy managements, adopted the circuit design that complexity is different, aspect energy acquisition, adopt boosting and MPPT maximum power point tracking circuit design of relative complex, realize the utilization for more small energy; In energy management use, adopted energy buffer setting, this module can be when energy be sufficient storage compartment energy, in order to use when the energy shortage, effectively solved the faint problem that provides wireless sensor network node to use of being not enough to of miniature thermoelectric generator energy output.This circuit is abandoned the circuit design mode of this relative highly energy-consuming of Single-chip Controlling simultaneously, and adopted the arrange in pairs or groups mode of corresponding discrete component of comparator and pressurizer to control output, can realize the wireless sensor node that the stable output of voltage supplies with below and use.

The structure of transmitting terminal of the wireless sensor network node of miniature thermoelectric generator power supply as shown in Figure 1.As shown in Figure 1, the transmitting terminal structure of the wireless sensor network node of miniature thermoelectric generator power supply is comprised of temperature difference power collector, the booster circuit with MPPT function, energy buffer and system load (wireless sensor node).Temperature difference power collector is comprised of thermoelectricity conversion chip, can be according to how many decision thermoelectricity conversion chip surface area sizes of the size of actual application places and required electric energy and the number of plies of stack, in order to meet different applied environments.Electric power management circuit is mainly to consist of MPPT maximum power point tracking module (MPPT), electric energy output interface, charger (DC-DC boost module), energy buffer.Wherein energy buffer circuit consists of super capacitor, comparator circuit and voltage regulator circuit.Load mainly comprises Temperature Humidity Sensor, microprocessor and wireless communication module, and microprocessor, by the humiture data that collect, is launched by wireless transmitter module.

As shown in Figure 1, in the wireless sensor network node of miniature thermoelectric generator power supply, power supply energy management circuit (PMC) is an extremely important ring, and the circuit function that it comprises is many and important, is the key point of miniature thermoelectric generator energy collecting system.Power supply energy management circuit has mainly comprised following function in the present invention, MPPT maximum power point tracking, DC-DC boost conversion and energy snubber.

As shown in Figure 2, this power supply energy management circuit is mainly to consist of chip BQ25504, MIC841N, TPS78001 and energy storage capacitor and their corresponding peripheral circuits.Extra low voltage boost conversion and managing chip BQ25504, low-power consumption multifunctional electric comparator MIC841N has formed the temperature difference energy acquisition of wireless sensor network node and the multi-functional of management use that miniature thermoelectric generator is supplied with together with linear voltage stabilization pio chip TPS78001.

In the present invention, the BQ25504 power management chip that company of Texas Instrument (TI) produces has mainly been realized from thermal power transfer module and has been drawn energy with super low-power consumption.BQ25504 is the efficient energy managing chip of 16 pins, 3mm*3mm packing, and 16 pins distribute successively counterclockwise, and the present invention, by reasonably applying the corresponding function of these pins, has realized the efficient management of miniature energy.In addition, a remarkable advantage of this chip is to have ultralow work starting resistor, and this makes it when steady operation, from being low to moderate the energy source of 80mv, to extract energy, and extra low voltage is carried out to boost conversion, so that subsequent conditioning circuit is stored use.In circuit of the present invention, the peripheral circuit of appropriate mix has been realized the MPPT maximum power point tracking that gathers electric energy from ultra low power energy source, and this confesses to system have vital effect for miniature temperature difference energy.By peripheral circuit, set overvoltage and under-voltage circuit protection simultaneously, guarantee the steady operation of chip.

MIC841N is two voltage comparators with internal reference voltage of a super low-power consumption.By being set, its voltage ratio upper and lower bound drives linear voltage regulator below in the present invention.The feature of its work is, by the voltage on continuous detection pin VDD, and compare with pin LTH and the upper operating voltage of setting of HTH, thereby the height of the voltage (being the output signal of pin OUT) of definite output, and then the operating state of control pressurizer TPS78001.

TPS78001 is the super low-power consumption pressurizer that Texas Instruments produces, it can realize the pressure stabilization function of circuit output voltage, by the resistance parameter of corresponding peripheral circuit is set, can make output obtain a stable voltage, so just can stably drive wireless sensor node below.

The chip below modules of foregoing circuit figure being comprised and associated electronic components, and working method and function are described in detail.

Circuit in Fig. 2 is the overall circuit figure of miniature thermoelectric generator self-contained electric system, according to the effect of side circuit, can be divided into three circuit, at this, with circuit A, B and C, replaces.

Circuit A be take DC-DC boost converter circuit and the energy storage circuit with MPPT function that BQ25504 chip is core; Circuit B be take two voltage comparator circuits that MIC841N chip is core; Circuit C be take the pressurizer output circuit that TPS78001 chip is core.

1, the detailed circuit schematic diagram of circuit A is as shown in Figure 3:

As shown in Figure 3, circuit A consists of electric energy management chip BQ25504 and peripheral circuit thereof.

First according to as the associated electrical components and parts of Fig. 3 connecting circuit A.TEG is miniature thermoelectric generator, and what its was exported is the naked voltage of thermoelectric conversion.TEG output is through resistance R ₁the VIN_DC end of (reality is TEG equivalent internal resistance) access BQ25504; Resistance R ₁through high frequency choke coil LBST access LBST end; Resistance R ₁capacitor C HVR ground connection after filtering; VIN_DC connects VOC_SAMP by resistance R oc2, and VOC_SAMP is by resistance R oc1 ground connection; VRDIV is by resistance R ov2 and resistance R ov1 ground connection; Between VRDIV and VBAT_OV, by resistance R ov2, be connected; VRDIV is by resistance R uv2 and resistance R uv1 ground connection; Between VBAT_UV and VRDIV, by resistance R uv2, be connected; VBAT_UV connecting resistance Ruv1 ground connection; VBAT_UV is by resistance R ok3, Rok2 and Rok1 ground connection; Between VBAT_UV and OK_HYST, by resistance R ok3, be connected; Between OK_HYST and OK_PRCG, by resistance R ok2, be connected; OK_PRCG is by resistance R ok1 ground connection; VSS and AVSS ground connection; VBAT meets energy storage capacitor Cstor by diode D1.

The major function of circuit A is MPPT, DC-DC boosting inverter, and energy storage circuit, below to how realizing these three functions, is described in detail.

MPPT maximum power point tracking (MPPT) is a kind of technology of maximum using electric energy that miniature thermoelectric generator produces.The present invention regulates the output voltage of the temperature difference chip of miniature thermoelectric generator by certain electrical module, thereby realizes the maximization of thermoelectric generator power output.According to the output characteristic curve of known miniature thermoelectric generator, when output voltage approximate greatly open circuit voltage 50% time can obtain maximum power output.The technology of extracting maximum power from TEG is mainly dynamically to change DC/DC converter switch frequency, the present invention utilizes BQ25504 to adopt resistance proportion divider method to realize half that output voltage is open circuit voltage according to this characteristic, and then has realized the maximization of power output.

As shown in Figure 3, in order to realize MPPT function, at pin 2(VIN_DC) and pin 3(VOC_SAMP) difference connecting resistance R _oC2and resistance R _oC1.Pin 2 passes through R _oC2connect pin 3, pin 3 passes through R _oC1ground connection, specifically as shown in circuit theory diagrams.

Then determine in the following way R _oC1and R _oC2resistance:

VIN_DC is voltage output end, passes through R _oC1and R _oC2dividing potential drop effect, make the voltage at VOC_SAMP place be:

$V_{\mathrm{VOC}\_\mathrm{SAMP}}=\mathrm{VIN}\_\mathrm{DC}\×\left(\frac{R_{\mathrm{OC}1}}{R_{\mathrm{OC}1}+R_{\mathrm{OC}2}}\right)$

Again because the voltage of TEG output approximate greatly open circuit voltage 50% time can obtain maximum power output, therefore

value should be so R _oC1=R _oC2, in circuit design reality, we have selected 10M Ω as its resistance, so R _oC1=R _oC2=10M Ω.

The magnitude of voltage of the every 16s once sampling of BQ25504 chip VOC_SAMP, can guarantee in the situation that the power output of thermoelectric generator changes, can accurately trace into the maximum point of miniature thermoelectric generator power output in the short period of time, realize the most effective electric energy acquisition.

Another most important function of BQ25504 is exactly can realize when steady operation continuing to draw energy from being low to moderate the voltage of 80mV, and this is very important for miniature thermoelectric generator.The charging circuit of BQ25504 is that the DC-DC boost module that is integrated in chip internal forms.Inner boost module is by pulse frequency modulated, input voltage regulation to be arrived to the energy storage device required voltage of chip.In order to realize the long-life efficiency operation of protection power storage (energy storage capacitor) equipment; the present invention is that charging circuit has been set under-voltage threshold value (UV) in conjunction with BQ25504; the threshold value of having charged (VBAT_OK); overvoltage threshold (OV); under-voltage and setting overvoltage threshold is respectively used to avoid energy storage capacitor energy storage device over-discharge can and overcharges, and extends as far as possible the work useful life of energy storage capacitor.The setting of VBAT_OK is used for controlling charge and discharge process, and then controls the workflow of whole circuit.

In the present invention, the actual conditions of combined charge circuit, set VBAT_OV=3.5V, VBAT_UV=2.8V, VBAT_OK=3V, VBAT_OK_HYST=3.2V.

Then according to following formula, determine the resistance of peripheral resistance:

$\mathrm{VBAT}\_\mathrm{UV}=\mathrm{VBIAS}(1+\frac{R_{\mathrm{UV}2}}{R_{\mathrm{UV}1}})---\left(1\right)$

$\mathrm{VBAT}\_\mathrm{OV}=\frac{3}{2}\mathrm{VBIAS}(1+\frac{R_{\mathrm{OV}2}}{R_{\mathrm{OV}1}})---\left(2\right)$

$\mathrm{VBAT}\_\mathrm{OK}\_\mathrm{PROG}=\mathrm{VBIAS}(1+\frac{R_{\mathrm{OK}2}}{R_{\mathrm{OK}1}})---\left(3\right)$

$\mathrm{VBAT}\_\mathrm{OK}\_\mathrm{HYST}=\mathrm{VBIAS}(1+\frac{R_{\mathrm{OK}2}+R_{\mathrm{OK}3}}{R_{\mathrm{OK}1}})---\left(4\right)$

In circuit, VBIAS is the internal reference voltage of chip BQ25504, and its value is 1.240V, and we arrange R in circuit design _uV1+ R _uV2=10M Ω, R _oV1+ R _oV2=10M Ω, R _oK1+ R _oK2+ R _oK3=10M Ω; In conjunction with equation (1), (2), (3), (4), obtain:

R _UV1=4.43M；R _UV2=5.57M；

R _OV1=5.31M；R _OV2=4.69M；

R _OK1=3.875M；R _OK2=5.5M；R _OK3=625K；

The energy buffer circuit of the present invention design is that outgoing position at BQ25504 chip is by an energy storage capacitor of a diode D1 access.By the application of energy storage capacitor, we can realize when thermal gradient energy is sufficient, and DC-DC conversion energy later not only can be supplied with wireless sensor node and use, and unnecessary energy can be stored in energy storage capacitor, realize the maximum saving of energy; In the time of electric weight deficiency that thermoelectric generator collects, energy storage capacitor can temporarily serve as the role of energy source, guarantee that wireless sensor node below effectively works, and because the existence of diode D1 has avoided energy storage capacitor oppositely to the situation of thermoelectric generator charging.

According to these resistances, select resistance connecting circuit can realize monitoring and the protection discharging and recharging for energy storage capacitor in actual applications, extend the working life of energy storage capacitor.

2, circuit B be take the comparator circuit that two voltage comparator MIC841N are core.

In the present invention, adopt MIC841N as voltage comparator, by this comparator, can realize the detection to super capacitor storage voltage, and the operating state of follow-up linear voltage regulator is controlled.Be the work reference circuit of MIC841N as shown in Figure 4, the present invention relies on reference circuit, and the device parameters such as peripheral resistance are rationally set, and realizes it and relatively controls function.

First, as shown in Figure 4, connect circuit, the positive pole of the energy storage capacitor Cstor of its Vin termination previous circuit; Vin end is held by resistance R 2 access LTH; LTH end is connected by resistance R 3 with HTH end; HTH terminating resistor R4 is ground connection then; Vout connects the EN end of TPS78001 chip.

Then according to following method, determine the resistance of the peripheral resistance of MIC841N:

According to the characteristic of MIC841N chip, low voltage threshold is:

$V_{\mathrm{IN}\left(\mathrm{lo}\right)}=V_{\mathrm{REF}}\left(\frac{R_2+R_3+R_4}{R_3+R_4}\right)---\left(5\right)$

High voltage threshold is:

$V_{\mathrm{IN}\left(\mathrm{hi}\right)}=V_{\mathrm{REF}}\left(\frac{{\mathrm{<figure-callout\; id="4"\; label="R"\; filenames="HDA0000403414430000012.png"\; state="\{\{state\}\}">R</figure-callout>}}_4+R_2+R_3}{R_4}\right)---\left(6\right)$

For MIC841N chip, V _rEF=1.240V.

Because the present invention will drive a wireless transmitter module, according to the operating voltage range of used wireless transmitter module (2.4V-3.0V), so V _{iN (lo)}=2.4V, V _{iN (hi)}=3.0V, can determine peripheral resistance R thus ₄, R ₂, R ₃resistance.In practical operation, set R ₄+ R ₂+ R ₃=1M Ω, in conjunction with formula (5) and formula (6), can calculate: R ₂=484K Ω, R ₃=413K Ω, R ₄=103K Ω.

The process that the voltage that the energy that miniature thermoelectric generator collects is energy storage capacitor two ends to energy storage capacitor charging raises gradually, and its discharge process is the process of the voltage slow decreasing at capacitor two ends.The V of the two voltage comparator MIC841N of input _inthe voltage at place be the voltage at capacitor two ends, and the Output rusults of MIC841N as shown in Figure 5 so.

From this Output rusults, can find out, the voltage that only has capacitor could be exported a high level in certain scope, and this exactly can be used for controlling the interruption of follow-up voltage regulator module, and then the most effectively utilizes energy.

3, circuit C is the voltage regulator circuit that energy storage capacitor can be discharged with burning voltage

In actual application, the voltage at this electrical energy storage of energy storage capacitor two ends can decline gradually along with the prolongation of discharge time.In the example of the present invention's research, the energy that miniature thermoelectric generator collects is very limited, and follow-up less radio-frequency transmitter module need to be operated in certain voltage range, the energy storage capacitor free discharge if left, less radio-frequency transmitter module only can be worked very short time so, the voltage of other times capacitor is less radio-frequency transmitter module use not all, this part electric energy will be wasted, in order to address this problem, must need to add a controlled pressurizer makes the discharge voltage of energy storage capacitor be stabilized in one can to make less radio-frequency transmitter module operational voltage value.

The present invention has adopted TPS78001 chip as voltage stabilizing output equipment.Be illustrated in figure 6 the work reference circuit figure of TPS78001.

First according to Fig. 6 connecting circuit figure.The positive pole of IN termination energy storage capacitor; EN enables the OUT end of termination MIC841N; Connecting resistance R5 between OUT end and FB end; FB termination R6 is ground connection then; A stable voltage of OUT end output, can arrange, and is 3V in the present invention, and the wireless transmitter module of supplying with is below used.

Then according to following methods, determine the resistance of peripheral resistance.

The output voltage of TPS78001 can be by setting resistance R ₁and R ₂any one value between 1.2V-5.1V of value stabilization.V _outand V _fBrelation as shown in equation (7).

$V_{\mathrm{OUT}}=V_{\mathrm{FB}}\&times;(1+\frac{R_5}{R_6})---\left(7\right)$

V _fBbe the reference voltage of an inner setting, its value is constant 1.216V, and V _out3V left and right need to be stabilized in, therefore two relations between resistance can be obtained.We set R in actual applications ₆=1M Ω, therefore $R_5=(\frac{3}{1.216}-1)\&times;R_6=1.467\mathrm{M\&Omega;}.$

Entire system basic circuit diagram in conjunction with Fig. 2, the whole working method of circuit of the present invention is as follows: TEG is converted to electric energy by thermal gradient energy, electric energy is by the maximum using of MPPT Interface realization electric energy power, then through DC-DC increasing apparatus, voltage is raised to 3V left and right, starts to charge to energy storage capacitor.If the power of the electric energy that TEG produces is very large, circuit charges to energy storage capacitor on one side, on one side driving comparator, pressurizer and wireless transmitter module below.If the electric energy that TEG produces is fainter, first to energy storage capacitor, charge, carrying out along with charging, when the voltage in energy storage capacitor reaches the threshold voltage of two voltage comparator MIC841N, a high level of comparator output, this high level will make pressurizer TPS78001 in enabling operating state, pressurizer steady operation, and then energy storage capacitor starts to power to wireless sensor node below; When energy storage capacitor is after electric discharge a period of time, its voltage drop, when voltage drop arrives the low pressure threshold of MIC841N, MIC841N output low level, now pressurizer TPS78001 is in interrupt status, and energy storage capacitor no longer externally discharges, and starts to continue charging, move in circles, circuit of the present invention can be worked down always.

Preferred forms: native system is the temperature difference energy and sensor node to be carried out integrated, can realize sensor node self-powered, thereby extend the useful life of sensor network.Native system comprises thermoelectric cell, has the DC-DC boost module of MPPT function, energy buffer module, and load.As shown in Figure 1, when application is of the present invention, the output of thermoelectric cell is accessed to the DC-DC boost module with MPPT function, then by the output energy storage after boosting in energy storage capacitor, comparator is controlled the charging and discharging state of energy storage capacitor by the magnitude of voltage in comparison energy storage capacitor, then by pressurizer, realize stable output, export to follow-up wireless sensor node and use.

Again in conjunction with the structure of detailed this PMC circuit of description of Fig. 2, TEG is miniature thermoelectric generator below, and what its was exported is the naked voltage of thermoelectric conversion.TEG output is through resistance R ₁the VIN_DC end of (being miniature thermoelectric generator internal resistance) access BQ25504; R ₁through inductance L BST access LBST end; R ₁capacitor C HVR ground connection after filtering; VIN_DC end connects VOC_SAMP by resistance R oc2 to be held, and VOC_SAMP end is by resistance R oc1 ground connection; VRDIV end is by resistance R ov2 and resistance R ov1 ground connection; Between VRDIV end and VBAT_OV end, by resistance R ov2, be connected; VRDIV end is by resistance R uv2 and resistance R uv1 ground connection; Between VBAT_UV end and VRDIV end, by resistance R uv2, be connected; VBAT_UV terminating resistor Ruv1 ground connection; VBAT_UV end is by resistance R ok3, Rok2 and Rok1 ground connection; Between VBAT_UV end and OK_HYST end, by resistance R ok3, be connected; Between OK_HYST end and OK_PRCG end, by resistance R ok2, be connected; OK_PRCG end is by resistance R ok1 ground connection; VSS end and AVSS end ground connection, it is anodal that VBAT end meets energy storage capacitor Cstor by diode D1.The vdd terminal of the anodal access of Cstor MIC841N; The positive pole of Cstor is held by resistance R 2 access LTH; LTH end is connected by resistance R 3 with HTH end; HTH terminating resistor R4 is ground connection then; The EN end of Vout termination TPS78001; GND holds ground connection.Cstor positive pole is held by the IN of a filter capacitor C1 access TPS78001; FB end is by resistance R 6 ground connection; Between FB end and OUT end, meet R5; GND holds ground connection; OUT end is exported to load (wireless sensor node) power supply below.

In experiment, through test, this circuit can draw energy under the extra low voltage from thermoelectric voltage 0.08V, has farthest utilized miniature thermal gradient energy.When thermoelectric cell output voltage is too low, now to energy storage capacitor, charge, when being charged to suitable magnitude of voltage, wireless sensor module below is just started working, so its operating state is interruption work.If the naked output voltage through test thermoelectric cell reaches 1.2V and when above, can directly power for wireless sensor node, can guarantee the work of wireless sensor node continous-stable.

It will be appreciated by those skilled in the art that accompanying drawing is the schematic diagram of a preferred embodiment, the invention described above embodiment sequence number, just to describing, does not represent the quality of embodiment.

The foregoing is only preferred embodiment of the present invention, in order to limit the present invention, within the spirit and principles in the present invention not all, any modification of doing, be equal to replacement, improvement etc., within all should being included in protection scope of the present invention.

Claims (4)

1. the wireless sensor node stable power-supplying system based on miniature thermoelectric generator, comprise: for collecting the temperature difference power collector of electric energy, it is characterized in that, described temperature difference power collector connects electric power management circuit, described electric power management circuit is processed rear stable transfer to the load circuit being comprised of Temperature Humidity Sensor, microprocessor and wireless communication module by the electric energy of collecting, for described load circuit power supply, the wet temp data that described microprocessor collects described Temperature Humidity Sensor are launched by described wireless communication module;

Wherein, described electric power management circuit is by two parts the electric circuit constitute, and first's circuit comprises: boost converter circuit and energy storage circuit; Second portion circuit is energy buffer circuit, and described energy buffer circuit comprises: two voltage comparator circuits and pressurizer output circuit.

2. a kind of wireless sensor node stable power-supplying system based on miniature thermoelectric generator according to claim 1, is characterized in that, described boost converter circuit and energy storage circuit comprise: miniature thermoelectric generator TEG,

What described miniature thermoelectric generator TEG exported is the naked voltage of thermoelectric conversion, and described miniature thermoelectric generator TEG output is through resistance R ₁the VIN_DC end of access BQ25504 chip; Resistance R ₁through high frequency choke coil LBST access LBST end; Resistance R ₁capacitor C HVR ground connection after filtering; VIN_DC connects VOC_SAMP by resistance R oc2, and VOC_SAMP is by resistance R oc1 ground connection; VRDIV is by resistance R ov2 and resistance R ov1 ground connection; Between VRDIV and VBAT_OV, by resistance R ov2, be connected; VRDIV is by resistance R uv2 and resistance R uv1 ground connection; Between VBAT_UV and VRDIV, by resistance R uv2, be connected; VBAT_UV connecting resistance Ruv1 ground connection; VBAT_UV is by resistance R ok3, Rok2 and Rok1 ground connection; Between VBAT_UV and OK_HYST, by resistance R ok3, be connected; Between OK_HYST and OK_PRCG, by resistance R ok2, be connected; OK_PRCG is by resistance R ok1 ground connection; VSS and AVSS ground connection; VBAT meets energy storage capacitor Cstor by diode D1.

3. a kind of wireless sensor node stable power-supplying system based on miniature thermoelectric generator according to claim 2, wherein, described pair of voltage comparator circuit comprises: MIC841N chip,

The positive pole of the Vin termination energy storage capacitor Cstor of MIC841N chip; Vin end is held by resistance R 2 access LTH; LTH end is connected by resistance R 3 with HTH end; HTH terminating resistor R4 is ground connection then; Vout connects pressurizer output circuit.

4. a kind of wireless sensor node stable power-supplying system based on miniature thermoelectric generator according to claim 3, wherein, described pressurizer output circuit comprises: TPS78001 chip,

The positive pole of the IN termination energy storage capacitor Cstor of TPS78001 chip; EN enables the output of termination MIC841N chip; Connecting resistance R5 between OUT end and FB end; FB terminating resistor R6 is ground connection then; A stable voltage of OUT end output.

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