CN103105526B - The verification method that signal waveform affects resonant inducing wireless energy transmission efficiency - Google Patents

Abstract

The invention provides the verification method that a kind of signal waveform affects resonant inducing wireless energy transmission efficiency, for the wireless energy transfer system of a middle distance, the present invention adopts magnetic coupling resonant inducing mode to carry out energy transferring, a suitable Energy Transfer tuning-points can searched out after theory calculate, and verify with experiment, discovery deviation is little, in wireless energy transfer process, can affect the transfer efficiency of whole system in the waveform change of the input signal of transmitting terminal.

Description

The verification method that signal waveform affects resonant inducing wireless energy transmission efficiency

Technical field

The present invention relates to radio energy transmission technique field, especially relate to the verification method that a kind of signal waveform affects resonant inducing wireless energy transmission efficiency.

Background technology

Magnetic coupling resonance type wireless energy transmission technology is the frontier that domestic and international academia and industry member start to explore, the fundamental research of the multi-crossed disciplines such as current collection magnetic field, power electronics, high-frequency electronic, electromagnetic induction, coupled wave theory and applied research, belong to the advanced subject of electric energy transportation art in the world.Resonant mode energy transmission technology utilizes two electromagnetic systems with identical particular resonant frequency, when certain distance, because electromagnetic coupled produces resonance, carries out energy transferring.In general, two electromagnetic systems having a certain distance are weak coupling each other, if but the natural resonance frequency of two systems is identical, then strong magnetic resonance can be produced, if a side is constantly for system provides energy, and the opposing party's consumed energy, then achieve the transmission of energy.

Magnetic coupling resonance type wireless energy transmission technology and induction type wireless energy transmission technology difference are this technological incorporation resonance technique, not only increase the transmission range of energy, and improve the transfer efficiency of energy.In addition, this technology produces harm unlike microwave to human body, because human body is as non-magnetic object, be exposed in strong magnetic field circumstance and do not have any impact, moreover, the ultimate principle that this technology realizes Energy Transfer is resonance, and the resonant body only having resonance frequency identical is just likely affected, so need not worry that it produces harm to human body and surrounding objects.

So-called wireless power transmission (WirelessPowerTransmission, WPT) is a kind of technology of carrying out energy transferring by means of electromagnetic field or electromagnetic wave.Along with development and the growth in the living standard of science and technology, resident's daily life come into more and more by the electrical equipment of the movement such as mobile phone, notebook, and wired charging of these equipment causes inconvenience to people, at the field of industrial production such as oil and mining, because special site work condition is difficult to rely on the traditional approach installed electric wiring to power.In electric power conveying, the location that the base station at the hilltop, isolated island etc. are special, traditional power transmission mode is also difficult to meet its power demands.Therefore, the importance developing radio energy transmission technology highlights day by day.

At present, according to wireless energy transfer principle, wireless energy transfer mode can be divided three classes: electromagnetic wave wireless energy transmission technology, induction type wireless energy transmission technology, magnetic coupling resonance type wireless energy transmission technology.

Electromagnetic wave wireless energy transmission technology directly make use of the principle that electromagnetic wave energy can be sent by antenna and receive, this technology can realize the wireless transmission of very high power, but in energy transport, transmitter must aim at receiver, and Energy Transfer limits by direction, and can not walk around or pass barrier, the aerial loss of microwave is also large, and efficiency is low, has grievous injury to human body and other biological, so this technology is generally applied to special occasions, as low orbit military satellite.

Induction type wireless energy transmission technology mainly utilizes electromagnetic induction principle, adopts loosely coupled transformer or separable transformer mode to realize energy wireless transmission.Because the transmission range of this technology too closely can not free the people from the constraint of electric wire, bring convenience to people's life, institute thinks that miniwatt mobile device such as the wireless chargings such as mobile phone are not popularized up till now.

Summary of the invention

For solving the problem of prior art, the present invention proposes the verification method that a kind of signal waveform affects resonant inducing wireless energy transmission efficiency.

Technical scheme of the present invention is the verification method that a kind of signal waveform affects resonant inducing wireless energy transmission efficiency, to a wireless energy transfer system, adopts following formula to ask for Energy Transfer tuning-points ω _r,

${\mathrm{\&omega;}}_r={\mathrm{\&omega;}}_n\sqrt{1-{2\mathrm{\&xi;}}^2},0<\mathrm{\&xi;}<1$

In formula, N is the coil turn of coupling, ω ₀for resonance frequency, μ ₀for permeability of vacuum, C is line capacitance;

Then the signal frequency of the various generation signal waveforms sending coil is all located at Energy Transfer tuning-points ω _ron, if the amplitude of various generation signal waveform is identical;

To often kind, signal waveform occurring adopts experimental circuit to verify, comprises and uses oscillograph to detect at Energy Transfer tuning-points ω _rthe output voltage of upper receiving coil, record output voltage effective value, and calculate the consumed power of receiving coil, the consumed power asking for receiving coil obtains transfer efficiency with the transmission power ratio value sending coil, is verified result according to transfer efficiency.

And, the obtain manner of the transmitted power of described transmission coil is, first take fixed signal generator output voltage, do not receive and send coil and use oscilloscope measurement voltage effective value now, access sends coil and uses oscilloscope measurement to send the voltage effective value at coil two ends again, utilize the pressure drop of two voltage effective values to calculate transmission coil current divided by internal resistance, then obtain the transmitted power sending coil.

And the generation signal waveform sending coil comprises square wave, triangular wave and sine wave.

And described experimental circuit comprises transmission loop, receiving loop and oscillograph,

Send loop comprise signal generator, the transmission coil of series connection and send electric capacity, signal generator is connected with oscillograph; Receiving loop comprise series connection receiving coil, receive electric capacity and load, load two ends bulb in parallel, receiving coil with receive capacitances in series after be connected oscillograph.

For the wireless energy transfer system of a middle distance, the present invention adopts magnetic coupling resonant inducing mode to carry out energy transferring, a suitable Energy Transfer tuning-points can searched out after theory calculate, and verify with experiment, discovery deviation is little, in wireless energy transfer process, the transfer efficiency of whole system can be affected in the waveform change of the input signal of transmitting terminal.Herein for resonant inducing formula wireless energy transfer system, propose and select square wave, sine to involve triangular wave three kinds of typical waveforms to test as the input signal sending coil, reaching a conclusion be different wave input signal is different on wireless energy transmission efficiency impact.Wherein square wave is maximum as transfer efficiency during generation signal, and the transfer efficiency of triangular wave is minimum.

Accompanying drawing explanation

Fig. 1 is the simple and easy schematic diagram of coil of the embodiment of the present invention.

Fig. 2 is the input waveform signal graph of the embodiment of the present invention, and wherein Fig. 2 a is square-wave waveform figure, Fig. 2 b is triangular wave oscillogram, and Fig. 2 c is sine waveform figure.

Fig. 3 is the wireless energy transfer rough schematic of the embodiment of the present invention.

Fig. 4 is 3 kinds of waveform signal wireless energy transfer output voltage comparison diagrams of the embodiment of the present invention.

Embodiment

Technical solution of the present invention is described in detail below in conjunction with drawings and Examples.

In magnet coupled resonant type wireless energy transmission system, it is a key technical problem that transfer efficiency controls, and sends coil wire diameter, pitch of the laps diameter in optimization, while texture of coil etc., also needs to consider the type problem sending coil input drive signal.The object that the present invention studies is mainly the resonant inducing wireless energy transfer of moderate distance scope (referring generally to about 1m to 10m), the variable affecting resonant inducing wireless energy transfer has a lot, embodiment is analyzed the impact of generation signal waveform on Energy Transfer, and carries out experimental verification.

Basic theories is analyzed:

In FIG, wherein K12 represents the coupling parameter between coil, the equivalent electrical circuit of transmitting terminal comprises signal generator power supply AC, transmission Coil resistance, the transmission coil inductance of series connection and sends coil capacitance, the equivalent electrical circuit of receiving end comprises the receiving coil internal resistance of series connection, receiving coil inductance and receiving coil electric capacity, send Coil resistance i.e. R equal to receiving coil internal resistance, send coil inductance i.e. L equal to receiving coil inductance, send coil capacitance i.e. C equal to receiving coil electric capacity.If t represents the time, s represents complex variable, T ₁, T ₂for time constant, the present invention can analyze that to obtain receiving end mathematical model as follows:

$T_1{T}_2\frac{d^2{u}_0\left(t\right)}{{\mathrm{dt}}^2}+T_2\frac{{\mathrm{du}}_0\left(t\right)}{\mathrm{dt}}+u_0\left(t\right)=u_i\left(t\right)---\left(1\right)$

$\mathrm{LC}\frac{d^2{u}_0\left(t\right)}{{\mathrm{dt}}^2}+\mathrm{RC}\frac{{\mathrm{du}}_0\left(t\right)}{\mathrm{dt}}+u_0\left(t\right)=u_i\left(t\right)---\left(2\right)$

$\begin{array}{cc}{\mathrm{LCs}}^2{u}_0\left(s\right)+\mathrm{RCsu}\left(s\right)+u_0\left(s\right)=u_i\left(s\right)& \left(3\right)\\ \frac{u_0\left(s\right)}{u_i\left(s\right)}=\frac{1}{{\mathrm{LCs}}^2+\mathrm{RCs}+1}& \left(4\right)\end{array}$

$\begin{array}{c}=\frac{\frac{1}{\mathrm{LC}}}{s^2+\frac{\mathrm{RC}}{\mathrm{LC}}s+\frac{1}{\mathrm{LC}}}\\ =\frac{{{\mathrm{\&omega;}}_n}^2}{s^2+{2\mathrm{\&xi;\&omega;}}_{n}s+{{\mathrm{\&omega;}}_n}^2}\end{array}---\left(5\right)$

Wherein ${2\mathrm{\&xi;\&omega;}}_n=\frac{R}{L},$ $\mathrm{\&xi;}=\frac{R\sqrt{C}}{2\sqrt{L}},$ ${\mathrm{\&omega;}}_n=\frac{1}{\sqrt{\mathrm{LC}}}$

Wherein, u ₀t () represents output voltage, u _it () represents input voltage.

The amplitude versus frequency characte of this transport function is analyzed, the resonance frequency that the present invention asks the point (tuning-points) at its maximum value place can obtain in resonance manifold type wireless energy transfer system, i.e. Energy Transfer tuning-points ω _r:

${\mathrm{\&omega;}}_r={\mathrm{\&omega;}}_n\sqrt{1-{2\mathrm{\&xi;}}^2},0<\mathrm{\&xi;}<1.$

Wherein ω _nfor undamped oscillation frequency, ξ is system damping ratio, when ξ=0, and ω _r=ω _nnamely when pair side's (receiving end) resistance is 0: resonance frequency=without resistance state self-excited oscillatory frequency, the resistance of secondary is the smaller the better.

There is signal type:

In various AC signal, conventional waveform mainly contains three kinds, square wave, sine wave and triangular wave, only choose the generation signal of these three kinds of typical waveforms as wireless energy transfer primary circuit in the present invention, signal frequency is all located on tuning-points, is 2.174MHz.Oscillogram is shown in Fig. 2 input waveform signal graph in accompanying drawing, and wherein Fig. 2 a is square-wave waveform figure, Fig. 2 b is triangular wave oscillogram, and Fig. 2 c is sine waveform figure, and horizontal ordinate is T/ms, chronomere ms, and ordinate is Vin/v, input voltage unit V.

In wireless energy transfer, its process is a kind of conversion of energy in fact, because the energy that signal occurs directly can have influence on the Energy transmission of transmitting terminal, the present invention is necessary simply to analyze three kinds of typical wave type energy, and power is a kind of form of expression of signal energy, with the energy of power measurement signal, average power signal P=W/T, wherein W is the energy of signal; T is the signal a certain cycle.

In this research contents, its resistance of signal generator of the present invention is fixing, P=U ²/ R, R are resistance, and so the tolerance of power just can be decided by the voltage U of signal, and the voltage effective value choosing signal in this present invention carries out analyzing the energy spectrometer replaced there is signal.

In three kinds of typical waveforms, the present invention knows that the frequency of three kinds of waveforms is all identical, and when voltage max is equal, the present invention compares its effective value, and suppose that voltage max is Vm, the cycle is T.

Square wave is had $\left\{\begin{array}{c}{V}_{\mathrm{Fr}}=\sqrt{\frac{{\&Integral;}_0^{T/2}{\mathrm{Vm}}^2\mathrm{dt}}{T/2}},0<t<\frac{T}{2}\\ V_{\mathrm{Fr}}=\sqrt{\frac{{\&Integral;}_{T/2}^T{(-\mathrm{Vm})}^2\mathrm{dt}}{T/2}},\frac{T}{2}<t<T\end{array}\right.---\left(6\right)$

Triangular wave is had $\left\{\begin{array}{c}{V}_{\mathrm{Sr}}=\sqrt{\frac{{\&Integral;}_{-T/4}^{T/4}{(4\&times;\mathrm{Vm}\&times;t/T)}^2\mathrm{dt}}{T/2}},\frac{-T}{4}<t<\frac{T}{4}\\ V_{\mathrm{Sr}}=\sqrt{\frac{{\&Integral;}_{T/4}^{3T/4}{(-4\&times;\mathrm{Vm}\&times;(t-\frac{T}{2})/T)}^1\mathrm{dt}}{T/2}},\frac{T}{4}<t<\frac{3T}{4}\end{array}\right.---\left(7\right)$

Sine wave is had $V_{\mathrm{Zr}}=\sqrt{\frac{{\&Integral;}_0^T{(\mathrm{Vm}\&times;\sin \mathrm{\&omega;t})}^1\mathrm{dt}}{T}},0<t<T---\left(8\right)$

Wherein V _frfor the voltage effective value of square wave; V _srfor the voltage effective value of triangular wave, V _zrfor the voltage effective value of sine wave.

Can be calculated V _fr=Vm, $V_{\mathrm{Sr}}=\mathrm{Vm}/\sqrt{3},$ $V_{\mathrm{Zr}}=\mathrm{Vm}/\sqrt{2},$ ω is sinusoidal wave angular frequency.

The energy of square-wave signal is maximum as can be seen from the results, and signal is given the transmission resonant energy that coil obtains and also will be maximized.

Experimental circuit provided by the invention comprises transmission loop, receiving loop and oscillograph, and send loop and comprise signal generator, the transmission coil of series connection and send electric capacity, signal generator is connected with oscillograph; Receiving loop comprise series connection receiving coil, receive electric capacity and load, load two ends bulb in parallel, receiving coil with receive capacitances in series after be connected oscillograph.For the sake of ease of implementation, the detailed protocol of embodiment is provided:

Select the enameled wire of multiply to carry out the making of coil in the present invention, the number of turn is 10 circles, the radius 15cm often enclosed, and the vertical range between homemade two coils is 80cm, and what wherein electric capacity was selected is that ceramic condenser capacity is less, selects 15pF electric capacity.When above-mentioned material can guarantee to test normally carry out the present invention do not change, the variable of change is the type input of waveform.The signal generator model selected is EE1642B1, and its internal resistance is 50 Europe, and the DS1022C of binary channels RIFOL selected by oscillograph, and actual circuit structure is V in Fig. 3 wireless energy transfer rough schematic _srepresent the supply voltage of signal generator inside, V _ireflection sends the voltage at coil two ends, V _othe voltage at reflection receiving coil two ends.As shown in Figure 3, the signal generator of transmitting terminal is connected with oscillograph, passes through voltage source V _sthere is provided operating power and energy for whole system to transmission loop power supply, be equivalent to input signal, but the power P i of input signal is voltage source power subtraction signal generator internal resistance R in efficiency calculation _sused up power, simultaneously serial transmission coil and electric capacity; Oscillograph records and sends voltage V _i.In receiving loop, receiving coil is connected oscillograph, oscilloscope measurement output voltage V with after reception capacitances in series _o, whole receiving loop is by receiving coil, reception electric capacity and load R _obe in series, for convenience of observing load R _otwo ends bulb in parallel.

In experimental circuit, want clearly demarcated variable and invariant, in an experiment to three kinds of different wave, its peak value is all identical, first to a wireless energy transfer system, adopts following formula to ask for Energy Transfer tuning-points ω _r,

${\mathrm{\&omega;}}_r={\mathrm{\&omega;}}_n\sqrt{1-{2\mathrm{\&xi;}}^2},0<\mathrm{\&xi;}<1$

In formula, N is the coil turn of coupling, ω ₀for resonance frequency, μ ₀for permeability of vacuum, C is line capacitance.

Oscillograph is used to detect in resonance frequency omega _rthe output voltage of upper receiving coil, record output voltage effective value, and calculate the consumed power of receiving coil.Experiment needs the transmitted power sending coil to calculate, because Equipment may direct measure coil currents, first can take fixed signal generator output voltage, do not receive and send coil and use oscilloscope measurement voltage effective value now, access sends coil and uses oscilloscope measurement to send the effective value at coil two ends again, because the internal resistance of known signal generator can utilize two effective value pressure drops to calculate transmission coil current divided by internal resistance, namely the transmitted power sending coil can be obtained, then received power (i.e. the consumed power of receiving coil) is used can transfer efficiency to be obtained than transmitted power.

Signal waveform is there is and adopts experimental circuit to verify in embodiment to often kind, comprise the output voltage using oscillograph to detect receiving coil on resonance frequency omega r, record output voltage effective value, and calculate the consumed power of receiving coil, the consumed power asking for receiving coil obtains transfer efficiency with the transmission power ratio value sending coil, is verified result according to transfer efficiency.To different wave, provide the checking of transfer efficiency difference as follows:

Analyze the circuit in Fig. 3, the present invention can obtain the power that transfer efficiency ρ=Po/Pi, Po represents receiving coil, and Pi represents the power sending coil, can obtain in receiving end the present invention

$\mathrm{Pi}=\frac{V_s-V_o}{R_s}\&times;V_i,\mathrm{Po}=\frac{{\mathrm{Vo}}^2}{R_0}---\left(9\right)$

Do not consider that it affects because capacitance is less, wherein voltage is voltage effective value.

Through experiment measuring, and carry out record analysis to experimental data, the present invention can obtain voltage oscillogram, wherein has the difference under each waveform Vp-p same case to export, and the output voltage raw data that three kinds of waveforms are corresponding can see table:

The output voltage raw data table (unit is: V) that table 1 three kinds of waveforms are corresponding

From voltage oscillogram and in record data, the present invention recycles the transfer efficiency that above-mentioned said transfer efficiency computing formula can obtain corresponding to each waveform and is followed successively by

$\left\{\begin{array}{c}{\mathrm{\&rho;}}_F=6.2\%,\mathrm{Vsf}=10.128V,\mathrm{Vi}=9.7V,\\ {\mathrm{\&rho;}}_Z=5.5\%,\mathrm{Vsz}=8.290V,\mathrm{Vi}=7.87V,\\ {\mathrm{\&rho;}}_S=4.8\%,\mathrm{Vss}=7.403V,\mathrm{Vi}=7.01V,\end{array}\right|\mathrm{Rs}=50\mathrm{\&Omega;},\mathrm{Ro}=4.7\mathrm{k\&Omega;},\mathrm{Vo}=4.92V\}$

Wherein Vsf, Vsz, Vss represent the voltage Vs of square wave, sine wave, triangular wave, namely do not receive and send the output voltage of signal generator during coil, and Vo reflects the output voltage of receiving coil.Can be found out in transfer efficiency by result of calculation above, the transfer efficiency of square wave is maximum, and sine wave signal takes second place, and wherein triangular wave wireless energy transfer is minimum.

Waveform is different, and input voltage difference exports different checking:

Repeat experiment according to the circuit of Fig. 3, the variable of this experiment is that waveform is different, and the Vp-p of waveform is different, observes the output voltage of receiving end, and is depicted as visual picture.Due to the problem such as performance of signal generator, perform poor under high-frequency state, exporting square wave is not ideal square wave, the phenomenons such as triangular wave corner angle are not obvious, three kinds of waveform institutes are influenced identical, but do not affect this experiment, experimental analysis Fig. 4 is 3 kinds of waveform signal wireless energy transfer output voltage comparison diagrams.

From the above results, the present invention can see that the output voltage of square-wave signal is always the strongest output, and the output of triangular signal is more weak.

Generally speaking, the invention is intended to research and the waveform of signal occurs on the impact of wireless energy transmission efficiency, in the discourse process described, the transmission method of the resonant inducing that the present invention adopts carries out Energy Transfer, after carrying out simple theoretical analysis, the present invention has carried out experimental verification to it, can obtain conclusion.Carry out in the process of wireless energy transfer utilizing resonant inducing, its transfer efficiency is relevant with the input generation signal of transmitting terminal, in three kinds of classical generation signals, when wherein square wave is as input signal, the efficiency of wireless energy transfer is maximum, sine wave signal takes second place, and the transfer efficiency of triangular wave is the most weak.Through the checking to the problems referred to above, the present invention can improve the efficiency of wireless energy transfer system, in the selection of input drive signal, the present invention can select square wave as drive singal, the transfer efficiency that the present invention obtains in wireless energy system is like this maximum, decrease unnecessary energy loss, simultaneously also for the transmission range problem of infinite energy transmission system carries out base wad.

Specific embodiment described herein is only to the explanation for example of the present invention's spirit.Those skilled in the art can make various amendment or supplement or adopt similar mode to substitute to described specific embodiment, but can't depart from spirit of the present invention or surmount the scope that appended claims defines.

Claims (2)

1. the verification method that affects resonant inducing wireless energy transmission efficiency of signal waveform, is characterized in that: to the wireless energy transfer system of a middle distance, adopts following formula to ask for Energy Transfer tuning-points ω _r,

${\mathrm{\&omega;}}_r={\mathrm{\&omega;}}_n\sqrt{1-{2\mathrm{\&xi;}}^2},0<\mathrm{\&xi;}<1$

ω in formula _nfor undamped oscillation frequency, ξ is system damping ratio, when ξ=0, and ω _r=ω _nnamely when receiving end resistance is 0: resonance frequency=without resistance state self-excited oscillatory frequency, the resistance of receiving end is the smaller the better;

Then the signal frequency of the various generation signal waveforms sending coil is all located at Energy Transfer tuning-points ω _ron, if the amplitude of various generation signal waveform is identical;

To often kind, signal waveform occurring adopts experimental circuit to verify, comprises and uses oscillograph to detect at Energy Transfer tuning-points ω _rthe output voltage of upper receiving coil, record output voltage effective value, and calculate the consumed power of receiving coil, the consumed power asking for receiving coil obtains transfer efficiency with the transmission power ratio value sending coil, is verified result according to transfer efficiency;

The obtain manner of the transmitted power of described transmission coil is, first take fixed signal generator output voltage, do not receive and send coil and use oscilloscope measurement voltage effective value now, access sends coil and uses oscilloscope measurement to send the voltage effective value at coil two ends again, utilize the pressure drop of two voltage effective values to calculate transmission coil current divided by internal resistance, then obtain the transmitted power sending coil;

Described experimental circuit comprises transmission loop, receiving loop and oscillograph,

Send loop comprise signal generator, the transmission coil of series connection and send electric capacity, signal generator is connected with oscillograph; Receiving loop comprise series connection receiving coil, receive electric capacity and load, load two ends bulb in parallel, receiving coil with receive capacitances in series after be connected oscillograph.

2. the verification method that affects resonant inducing wireless energy transmission efficiency of signal waveform according to claim 1, is characterized in that: the generation signal waveform sending coil comprises square wave, triangular wave and sine wave.