Background technique
Wireless sensor network is by a large amount of sensor nodes multi-hops that mode is formed by wireless communication from group
Network system is knitted, it can be realized the acquisition quantization, processing fusion and transmission of data, and sensor node is wireless sensor network
Basic functional units, the basic comprising modules of sensor node have: sensing unit, processing unit, communication unit and power supply mould
Block.Wherein, power module provides energy for sensor node, is the basic module of entire wireless sensor network.By sensor
Node volumetric constraint, sensor node generally take limited battery to power, and energy is very limited.In order to solve using battery
Defect, energy collection technology develops rapidly, and there are the energy abundant in environment, such as luminous energy, thermal energy, vibrational energy and radio frequency
Energy, these green energy resources " inexhaustible ", and not can cause environmental pollution.
In order to reasonably store and using the collected energy of institute, the sensor node operation based on energy acquisition is necessary
Carry out effective energy management, management scheme is responsible for the high efficiency from environment and obtains energy, and to the use of this energy into
Row management.In order to reduce sensor node power consumption, sensor node uses operation-suspend mode substantially in management scheme at present
The mode of switching reduces power consumption, and when each run only completes a task and enters dormant state, farthest reduces energy
Consumption.
The existing sensor node structure by energy acquisition power supply is as shown in Figure 1, wherein energy acquisition unit is by ring
Border energy is converted to electric energy, and voltage transformation module is recycled to be converted into voltage (the i.e. voltage of suitable sensor node work
Value Vout), it is used so that sensor node is run, since environmental energy is faint, collected electric energy is not enough to maintain sensor section
Point is constantly in operating status, and usually in a dormant state, power consumption is very small for sensor node, and collected electric energy is first stored in
In energy storage units, to energy stores (the i.e. output end voltage V of energy storage units to a certain extentcapIt is increased to certain
Value) after, sensor node opens work, after completing a task, and enters dormant state.It is deposited since sensor node consumes
The energy of storage, the output end voltage V of energy storage unitscapIt will appear decline, energy acquisition and storage need be carried out again,
Sensor node task next time can be executed.
Ideally, the collecting energy stored every time can just maintain one task of sensor node to complete, and make in this way
Sensor node is in optimal operation -- suspend mode -- and switches between off-position.But due to the fact, that
(1), environmental energy is uncertain, and when collected energy is small when big, and the energy stored every time is not necessarily equal;
(2), repeatedly weight is needed in sending and receiving data uncertain (such as blocking, multipath effect) due to sensor node
Hair, therefore the time required for the same task is completed is not fixed length.
Therefore, the collecting energy stored every time is difficult to just maintain one task execution of sensor node, most of to go out
Existing following situation:
(a), after sensor node completes a task, there is also extra energy for energy storage units, this shows early period
The time of energy acquisition is partially long, i.e. the sensor node dormancy time is partially long.
(b), one task of sensor node is not yet fully completed, and energy storage units cannot normally supply for sensor node
Electricity causes sensor node out of service because of no power supply, i.e. the time of energy acquisition early period is partially short, is not enough to maintain to sense
Device node completes a complete task.
For problem (a), although not the influencing sensor node of the task is completed, when extending the waiting of task execution
Between, for the Internet of Things relatively high for requirement of real-time, not up to perfect condition;For problem (b), not only sensor node
The task of not completing, and collected energy early period of energy storage units storage is consumed, the company of there is also under harsh conditions
Continuing several or even each circulation is all consumption collected energy early period, and sensor node is unable to complete one complete
Business.
Summary of the invention
Primary technical problem to be solved by this invention is the status for the prior art, and it is maximum to provide a kind of energy
Using collected energy and accelerate sensor node the task execution period circulation the sensor section based on energy acquisition
Point power supply system.
Second technical problem to be solved by this invention is the status for the prior art, is provided a kind of by state prison
Survey the power supply for accelerating the sensor node power supply system based on energy acquisition of the circulation in task execution period of sensor node
Method.
The technical scheme of the invention to solve the technical problem is: a kind of sensor node based on energy acquisition
Power supply system, including the energy acquisition unit, energy storage units and voltage transformation list for environmental energy to be converted into electric energy
Member, the energy acquisition unit, energy storage units and voltage transformation module are sequentially connected, the voltage transformation module output end
Connection sensor node, the voltage that the transformation of electrical energy for storing energy storage units works at suitable sensor node,
It being characterized in that: further including power supply coordinator, the power supply coordinator includes voltage monitor and electric-controlled switch, and the of electric-controlled switch
The connection of the output end of one end and energy storage units, the second end of electric-controlled switch and the input terminal of voltage transformation module connect;Institute
The first input end for stating voltage monitor is connect with energy storage units, the collection of energy shape for collecting energy memory cell
State;Second input terminal of the voltage monitor is connect with sensor node, for acquiring the working condition of sensor node;Institute
The control terminal of the first output end and electric-controlled switch of stating voltage monitor connects, for controlling the disconnection and closure of electric-controlled switch;
The second output terminal of the voltage monitor is connect with sensor node, for energy collection status to be transmitted to sensor section
Point;The collection of energy state is that energy value meets sensor node work or energy value is unsatisfactory for sensor node work.
Specifically, when sensor node is in running order, the electricity of the second input terminal acquisition of the voltage monitor
It puts down as high level;When sensor node is in off working state, the level of the second input terminal acquisition of the voltage monitor
For low level, off working state is divided into two kinds of situations: the first, when the output end voltage of energy storage units is greater than minimum voltage
When being worth and being less than maximum voltage value, sensor node is indicated in a dormant state;Second, the output end electricity of energy storage units
When pressing electricity and minimizing voltage value, then voltage monitor control electric-controlled switch disconnects the connection with voltage transformation module, voltage
The output end voltage of converter unit is zero, and the level of the second input terminal acquisition of the voltage monitor is pulled to low level;
When the output end voltage of energy storage units rises to maximum voltage value, then the second output of the voltage monitor
End voltage is set to high level, and notice sensor node opens work;Second input end of the voltage monitor in low level,
I.e. sensor node is in off working state, and the second output terminal voltage of the voltage monitor is set to low level;
Wherein maximum voltage value and minimum amount of voltage that are two preset voltage values.
A kind of method of supplying power to of the sensor node power supply system based on energy acquisition, it is characterised in that: including following step
It is rapid:
When step (1), original state, the output end voltage of energy storage units and the output end voltage of voltage transformation module
It is zero, the level of the second input terminal of the second output terminal and voltage monitor of voltage monitor is low level, automatically controlled to open
Shutdown is opened, and is disconnected between energy storage units and voltage transformation module;
Step (2), energy acquisition unit start collecting energy, and energy storage units start to store up the energy of acquisition
It deposits, when the output end voltage of energy storage units reaches the minimum operating voltage of voltage monitor, voltage monitor starts work
Make;
Step (3), when the output end voltage of energy storage units reaches maximum voltage value, then follow the steps (4), start
One duty cycle;
Step (4), voltage monitor control electric-controlled switch closure, lead energy storage units mutually with voltage transformation module
Logical, voltage transformation module is powered to sensor node, while the second output terminal voltage of voltage monitor is set to high level, voltage
Monitor notifies sensor node to open work;
Step (5), sensor node open a task execution period, at this time the second input terminal acquisition of voltage monitor
Level be high level, sensor node carries out data transmit-receive and sensor monitoring task, sensor node is judged after a period of time
A complete task that whether it is executed normally, after sensor node, which works normally, completes a task, sensor node will be in not
Then dormancy state is transferred to step (6) at this point, the level that the second input terminal of voltage monitor acquires is low level;Conversely,
In sensor node execution task, when energy storage units output end voltage be lower than minimum amount of voltage that, then go to step (7),
Open an improper duty cycle;
Step (6), energy acquisition unit continuation collecting energy make energy storage units continue to charge, and go to step (3), pass
The execution of sensor node progress next task;
The first output end control electric-controlled switch disconnection of step (7), voltage monitor, becomes energy storage units and voltage
It changes between unit and disconnects, voltage transformation module output end voltage is zero, at this point, the second input terminal of voltage monitor acquires
Voltage be low level, second output terminal voltage is set to low level, is transferred to step (3) by voltage monitor.
Preferably, the energy storage units are capacitor.
In order to further speed up the circulation in sensor node task execution period, maximal efficiency uses collected energy,
I.e. collected energy has just executed a task for sensor node every time, and the value of capacitor needs to meet following formula:
Wherein, C is capacitance, and T is a task execution time of sensor node, VoutFor the defeated of voltage transformation module
The voltage of outlet voltage, i.e. sensor node work, IoutFor the average output current of voltage transformation module, i.e. sensor node
Average current when operation, η are the transfer efficiency of voltage transformation module, VmaxFor the preset maximum of output end of energy storage units
Voltage value, VminFor the preset minimum amount of voltage that of output end of energy storage units, V is the input voltage of voltage transformation module.
Compared with the prior art, the advantages of the present invention are as follows: by adding power supply coordinator, voltage monitor can pass through
The state of the level of two input terminals acquisition and the voltage monitoring sensor node of second output terminal and energy storage units, works as energy
The output end voltage of storage unit reach meet sensor node work when, at once control sensor node open work, and
When sensor node executes task and is also not finished, when the output end voltage of energy storage units is unsatisfactory for sensor node work
When, electric-controlled switch is disconnected at once, be stopped the power supply of sensor node and voltage transformation module, is reduced the consumption of energy, from
And the circulation and maximal efficiency for accelerating the sensor node task execution period make sensor node in work using the energy of acquisition
Adaptively switch in the state of work-suspend mode-power-off.
Specific embodiment
The present invention will be described in further detail below with reference to the embodiments of the drawings.
As shown in Fig. 2, a kind of sensor node power supply system based on energy acquisition includes for converting environmental energy
At the energy acquisition unit of electric energy, energy storage units, power supply coordinator and voltage transformation module, energy acquisition unit, energy
Storage unit and voltage transformation module are sequentially connected, and voltage transformation module output end connects sensor node, for depositing energy
The voltage that work at suitable sensor node of transformation of electrical energy of storage unit storage, coordinator of powering include voltage monitor and automatically controlled
The first end of switch K, electric-controlled switch K and the output end of energy storage units connect, the second end and voltage transformation of electric-controlled switch K
The input terminal of unit connects;The first input end of voltage monitor is connect with energy storage units, single for collecting energy storage
The collection of energy state of member;Second input terminal of voltage monitor is connect with sensor node, for acquiring sensor node
Working condition;First output end of voltage monitor is connect with the control terminal of electric-controlled switch K, for controlling the disconnected of electric-controlled switch K
It opens and is closed;The second output terminal of voltage monitor is connect with sensor node, for energy collection status to be transmitted to sensing
Device node;Collection of energy state is that energy value meets sensor node work or energy value is unsatisfactory for sensor node work.
When sensor node is in running order, the level of the second input terminal En acquisition of voltage monitor is high electricity
It is flat;When sensor node is in off working state, the level of the second input terminal En acquisition of voltage monitor is low level, non-
Working condition is divided into two kinds of situations: the first, as the output end voltage V of energy storage unitscapGreater than minimum amount of voltage that VminAnd
Less than maximum voltage value VmaxWhen, indicate sensor node in a dormant state;Second, the output end electricity of energy storage units
Press VcapElectric discharge minimizes voltage value VminWhen, then voltage monitor control electric-controlled switch K disconnects the company with voltage transformation module
It connects, the output end voltage V of voltage transformation moduleoutIt is zero, the level of the second input terminal En acquisition of voltage monitor is pulled to low
Level.
As the output end voltage V of energy storage unitscapRise to maximum voltage VmaxWhen, then the second output of voltage monitor
End Int voltage is set to high level, and notice sensor node opens work, and voltage monitor is controlled electric-controlled switch K at this time
Closure, makes energy storage units be conducted with voltage transformation module, and voltage transformation module is powered to sensor node, makes sensor
Node is started to work;Second input terminal En of voltage monitor is in low level, i.e. sensor node is in off working state, electricity
The second output terminal Int voltage of pressure monitor is set to low level;Wherein maximum voltage value VmaxWith minimum amount of voltage that VminIt is two
Preset voltage value.
As shown in figure 3, when for using the method for supplying power to of the sensor node power supply system, the output end of energy storage units
Voltage Vcap, voltage transformation module output end voltage Vout, the second output terminal Int level and voltage monitor of voltage monitor
The second input terminal En level state variation diagram, the method for supplying power to using the sensor node power supply system includes following step
It is rapid:
When step (1), original state, the output end voltage V of energy storage unitscapWith the output end of voltage transformation module
Voltage VoutIt is zero, the level of the second input terminal En of the second output terminal Int and voltage monitor of voltage monitor is low
Level, electric-controlled switch K are disconnected, are disconnected between energy storage units and voltage transformation module;
Step (2), energy acquisition unit start collecting energy, and energy storage units start to store up the energy of acquisition
It deposits, as the output end voltage V of energy storage unitscapWhen reaching the minimum operating voltage of voltage monitor, voltage monitor starts
Work;
Step (3), the output end voltage V when energy storage unitscapReach maximum voltage value VmaxWhen, it thens follow the steps
(4), start a duty cycle, duty cycle I as shown in Figure 3;
Step (4), voltage monitor control electric-controlled switch K closure, lead energy storage units mutually with voltage transformation module
It is logical, the output end voltage V of voltage transformation moduleoutHaving output (a in such as Fig. 3), voltage transformation module is powered to sensor node,
The second output terminal Int voltage of voltage monitor is set to high level (b in such as Fig. 3) simultaneously, and voltage monitor notifies sensor section
Point opens work;
Step (5), sensor node open a task execution period, and the second input terminal En of voltage monitor is adopted at this time
For the level integrated as high level (c in such as Fig. 3), sensor node carries out data transmit-receive and sensor monitoring task, sentences after a period of time
Link sensor node whether it is executed normally a complete task, after sensor node, which works normally, completes a task, sensor
Node will in a dormant state, at this point, the level that acquires of the second input terminal En of voltage monitor is low level (d in such as Fig. 3),
Voltage transformation module keeps output voltage V at this timeout(e in such as Fig. 3), is then transferred to step (6);Conversely, being held in sensor node
In row task, as the output end voltage V of energy storage unitscapLower than minimum amount of voltage that Vmin, then go to step (7), open one
A improper duty cycle;Duty cycle III as shown in Figure 3;
Step (6), energy acquisition unit continuation collecting energy make energy storage units continue to charge, at this time energy stores list
The output end voltage V of membercapSlowly become larger (f in such as Fig. 3), goes to step (3), and sensor node carries out holding for next task
Row, duty cycle II as shown in Figure 3;
The first output end control electric-controlled switch K disconnection of step (7), voltage monitor, makes energy storage units and voltage
It is disconnected between converter unit, voltage transformation module output end voltage VoutIt is zero (g in such as Fig. 3), at this point, voltage monitor
The second input terminal En acquisition level be low level (h in such as Fig. 3), second output terminal Int voltage is set to by voltage monitor
Low level (i in such as Fig. 3), is transferred to step (3), starts a new duty cycle, duty cycle IV and V as shown in Figure 3.
When due within the non-normal working period, electric-controlled switch K is disconnected, make energy storage units and voltage transformation module it
Separated connection, therefore after having terminated a non-normal working period, when energy storage units continue storage, since energy is deposited
Connection is disconnected between storage unit and voltage transformation module, thus stopped the power supply of voltage transformation module and sensor node,
But at the end of working normally the period, due to the output end voltage V of energy storage unitscapElectric discharge does not drop to minimum amount of voltage that
Vmin, voltage monitor do not control electric-controlled switch K disconnect with the connection of voltage transformation module, at this time energy storage units still with electricity
Converter unit connection is pressed, after working normally the period, energy acquisition unit is carried out in energy storage units charging process, by
It remains to power to voltage transformation module and sensor node in energy storage units, therefore the output end voltage of energy energy-storage units
VcapThe rate of climb is than (the output end voltage of the energy energy-storage units between duty cycle I and II in such as Fig. 3 under normal circumstances
VcapThe rate of climb) more faster (j in such as Fig. 3).
When being powered using the system, voltage monitor can be defeated by the second input terminal En level acquired and second
The state of outlet Int monitoring sensor node and energy storage units, to work as the output end voltage V of energy storage unitscapIt reaches
To maximum voltage value VmaxWhen, it can immediately control sensor node and open work, and task can be executed in sensor node
When being also not finished, as the output end voltage V of energy storage unitscapLower than minimum amount of voltage that Vmin, at once disconnect electric-controlled switch K with
The connection of voltage transformation module, stopped the power supply of sensor node and voltage transformation module, so that the consumption of energy is reduced,
Therefore the output end voltage V of energy energy-storage unitscapThe rate of climb of energy storage than more faster, accelerating sensing under normal circumstances
Device node tasks execute the period circulation and be capable of maximal efficiency using collected energy.
In the present embodiment, as shown in figure 4, energy acquisition unit is to collect antenna, RF-DC converter and voltage-doubler rectifier group
At energy storage units use capacitor C, and voltage transformation module uses DC-DC converter, and electric-controlled switch K uses electronic switch, receive
Collect antenna and receive RF energy, and received RF energy is input in RF-DC converter, is then turned by voltage-doubler rectifier
It is melted into direct current, and by capacitor C energy storage, send by electronic switch K to boosting in DC-DC converter, export stable direct current
Electric VoutIt is used to sensor node.
Voltage monitor is realized using super low-power consumption microprocessor or specific integrated circuit, for example, by using TI company
The super low-power consumption microprocessor of MSP430F1122, operating current only need 200uA@1MHz/2.2V, and dormant state lower needs
0.7 μ A, working power voltage 1.8V to 3.6V are wanted, 1 16 bit timing device and timer interruption, 10Bit/200ksps are possessed
ADC can be used to the output end voltage V of periodic monitor energy storage unitscap, voltage monitor the second input terminal En change feelings
Condition, the second output terminal Int of voltage monitor and control electric-controlled switch K closing or opening;As shown in figure 5, being microprocessor
Main program flow chart, groundwork be initialization ADC (analog-digital converter, Analog-to-Digital Converter) and
Timer interruption is set, and the timer interrupt interval time can set according to simulation accuracy, wherein as shown in fig. 6, being timer
Interrupt service subroutine flow chart, microprocessor is constantly in dormant state after the completion of the work of timer interrupt service subprogram;
As shown in fig. 7, voltage monitor is realized using specific integrated circuit, specific integrated circuit uses CMOS technology, and operating current reaches
To nA rank, so that its own is low in energy consumption, operating voltage is wide, as shown in fig. 7, electricity may be implemented using the specific integrated circuit
Press the function of monitor, wherein signal H is high level, Vmax、VminRespectively preset two threshold values, work as energy stores
The output end voltage V of unitcapIt is increased to maximum voltage value VmaxWhen, voltage comparator C1Output becomes high level by low level,
Trigger D2High level is exported, electronic switch K is closed;As the output end voltage V of energy storage unitscapIt is reduced to minimum voltage
Value VminWhen, voltage comparator C2Export low level, trigger D2It resets and resets, export low level, disconnect electronic switch K.In addition,
All NOT gates have schmidt trigger characteristic in Fig. 7, and its purpose is to prevent shake of the input signal near threshold value.
Electronic switch K can use N-MOS field-effect tube, its main feature is that high speed, high-performance, low-loss, low electric conduction
Resistance etc.;Existing N-MOS pipe product on the market can also be selected, as Toshiba (Toshiba) company SSM3K344R,
2SK1828。
DC-DC switching regulator can be used in DC-DC converter, and high efficiency switching regulator core existing on the market also can be selected
Piece, such as MAX17223/17221, minimum and maximum input voltage is up to 0.4V, 5.5V.
Energy storage units can select traditional rechargeable battery, novel thin film battery and capacitor to carry out energy to energy
Storage.Select super capacitor C as energy storage units in the present embodiment.
There are many wireless sensor node design scheme at present, such as bluetooth, ZigBee, LoRa, NB-IoT scheme.In order to realize
It acquires and cooperates with RF energy, using the I/O port of MCU as second signal En, the first signal Int connection, and second signal
En passes through a resistive pull-downs ground connection.
In the present embodiment, it is possible to measure the minimum value V of the output end voltage of storage unitmin, maximum value VmaxIt is pre- with capacitor C
If value, the selection of value will affect the accurate use of power supply coordinator.
A. the minimum value V of the output end voltage of energy storage unitsminIt chooses
When energy acquisition unit carries out energy acquisition, capacitor C, the output voltage of energy storage units can be outputed current to
VcapIt can gradually get higher, voltage monitor could work normally when only reaching the minimum operating voltage of voltage monitor, and only have
Voltage monitor could be by the output voltage V of energy storage units when working normallycapWith the output end voltage of energy storage units
Minimum value VminIt is compared, therefore the minimum value V of the output end voltage of energy storage unitsminValue have to be larger than voltage
The minimum operating voltage of monitor, and it is less than the maximum value V of the output end voltage of energy storage unitsmax.In addition, energy stores
The minimum value V of the output end voltage of unitminThe minimum input voltage of DC-DC converter must also be greater than.For example, RF energy
It when acquisition, is boosted by multistage voltage-doubler rectifier, the output end voltage V of energy storage units can be madecapReach 2.5V, and
The minimum operating voltage of the voltage monitor of CMOS technology can be as small as 1.25V, when DC-DC converter is switching regulator, switch
Voltage-stablizer undertakes minimum input voltage and is generally less than 1.25V (such as minimum input voltage of switching regulator MAX17223/17221 can
As low as 0.4V), therefore the minimum value V of the output end voltage of energy storage unitsmin1.25 can be chosen between 2.5V
Value, such as 1.5V.
B. the maximum value V of the output end voltage of energy storage unitsmaxValue range
According to the powered operation mechanism of formulation, it is evident that the maximum value V of the output end voltage of energy storage unitsmaxTake
Value has to be larger than the minimum value V of the output end voltage of energy storage unitsmin, but the output end of energy storage units cannot be greater than
Voltage VcapThe maximum value that can be reached.
C. the maximum value V of the output end voltage of energy storage unitsmaxWith the value of capacitor C
For energy acquisition, the value of storage capacitor C is the bigger the better, but its value is bigger, the output of energy storage units
Hold voltage VcapFrom the minimum value V of the output end voltage of energy storage unitsminIt is charged to the output end voltage of energy storage units
Minimum value VmaxTime it is longer, sensor node task processing cycle period it is also longer, influence sensor node appoint
Business executes the period;Capacitor C value is smaller, the output end voltage V of energy storage unitscapFrom the output end voltage of energy storage units
Minimum value VminIt is charged to the maximum value V of the output end voltage of energy storage unitsmaxTime it is shorter, the energy storage of capacitor C
It may be unable to maintain that the execution of one task of sensor node.Therefore, the maximum value of the output end voltage of energy storage units
Vmax, capacitor C value and a task execution time T of sensor node, power consumption P when sensor node is run0(or
It is the output voltage V of voltage transformation moduleoutWith average operating current Iout) related.
According to capacitor discharge principle, the output end voltage V of energy storage units can be obtainedcapThe voltage V in moment tt:
Vt=E × e(-t/RC) (1)
Wherein, E is voltage value when capacitor C is full of charge, and R is load value when capacitor C discharges.
When moment t is minimized tminWith maximum value tmaxWhen, capacitor C is discharged to voltage and becomes minimum value VminAnd maximum value
Vmax, it can be derived according to formula 1:
Choose (tmin-tmax) just it is equal to T, i.e. maximum value V of the capacitor C from the output end voltages of energy storage unitsmaxIt puts
Electricity to energy storage units output end voltage minimum value VminWhen sensor node just executed a task, then formula
(1) it converts are as follows:
T=RCln (Vmax/Vmin) (3)
I.e.
Wherein, T is a task execution time of sensor node, and R is DC-DC converter input load value, remembers R=
V2/P0, wherein P0, V be respectively DC-DC converter input power, input voltage, therefore formula (4) is transformed to
P is considered below0Problems of value.
Since the power consumption of sensor node operation is
P0=Vout×Iout (6)
Wherein, VoutThe voltage to work for the output end voltage namely sensor node of voltage transformation module;IoutFor voltage
The average current of average output current namely the sensor node work of converter unit.
In order to facilitate calculating, it is assumed that the transfer efficiency of DC-DC converter is η (η < 1), therefore in formula (5), P0It is taken as Vout
×Iout/ η, then formula (5) becomes
In view of capacitor C energy storage can guarantee the completion of one task of maintenance, therefore capacitor C value value as far as possible is suitably big, therefore can
Take V=Vmin, in order to accelerate the circulation in sensor node task execution period, maximal efficiency uses collected energy, i.e., every time
Collected energy has just executed a task for sensor node.When energy storage units are capacitor, capacitor C, energy
The minimum value V of the output end voltage of storage unitmin, energy storage units output end voltage maximum value VmaxValue and biography
One task execution time T of sensor node, output voltage VoutAnd average current I when sensor node operationoutBetween pass
System, is turned into from formula (7)
In the present embodiment, for the sensor node scheme of CC2640 chip, V is taken according to chip handbookout=3.3V, T=
3ms、Iout=15mA, i.e. sensor node operating voltage are 3.3V, operating current 15mA, and a duty cycle is 3ms;Simultaneously
Choose Vmin=1.5V;According to DC-DC converter chip handbook, transfer efficiency is generally η ≈ 0.9, therefore C, VmaxRelationship are as follows:
I.e.
Wherein C unit is μ F, VmaxUnit is V.As selection VmaxWhen=2.2V, C=191.48 (μ F) can be obtained.