CN203192172U - Security pre-warning system for electromagnetic radiation of wireless energy transmission system - Google Patents

Abstract

The utility model provides a security pre-warning system for electromagnetic radiation of a wireless energy transmission system. The security pre-warning system for electromagnetic radiation of the wireless energy transmission system includes a voltage current collecting module, a safe distance calculating module and a lamplight pre-warning system sequentially connected together. The voltage current collecting module is connected with a transmitting end and a receiving end in the wireless energy transmission system respectively. According to the utility model, a principle of coupling resonance and limiting values of a national electromagnetic radiation protection standard are utilized, a safe distance is calculated and a light alarm is given out when a value surpasses the predetermined pre-warning values. The security pre-warning system for electromagnetic radiation of the wireless energy transmission system provided by the utility model is instructive for electromagnetic radiation safety protection of workers and environments in application of the wireless energy transmission system.

Description

A kind of electromagnetic radiation safety pre-warning system of wireless energy transfer system

Technical field

The utility model belongs to the radio energy transmission technique field, relates in particular to a kind of electromagnetic radiation safety pre-warning system of wireless energy transfer system.

Background technology

Along with the continuous application of wireless energy transfer system, when bringing efficiently, transmitting advantage easily, the electromagnetic radiation that this system also exists when moving.Electromagnetic radiation is if exceed safe range, and its thermal effect influences the operate as normal of intracorporeal organ such as crystalline lens muddiness, cataract; Non-thermal effect disturbs human biological electricity, especially can produce interference to brain and electrocardio; When both are not able to do in time self-regeneration to people's injury, the electromagnetic radiation that human body is subjected to will be accumulated, and form permanent morbid state, go down cataract, leukaemia, brain tumor, angiocardiopathy, cerebral function obstacle, hypoimmunity etc. as muscle power.Therefore it is very necessary the electromagnetic radiation safe distance of wireless energy transfer system being carried out calculating and it is carried out early warning.

The utility model content

Problem at the background technology existence, the utility model provides a kind of electromagnetic radiation safety pre-warning system of wireless energy transfer system, it is according to voltage or the electric current of radio energy transmission system input, calculate the electromagnetic radiation safe distance of its magnetic field and electric field, and greater than distance to a declared goal the time, go out alarm signal by light flash.

For solving the problems of the technologies described above, the utility model adopts following technical scheme:

A kind of electromagnetic radiation safety pre-warning system of wireless energy transfer system comprises the electric current and voltage acquisition module, Calculation of Safety Distance module, the light early warning system that connect successively; The electric current and voltage acquisition module respectively with wireless energy transfer system in transmitting terminal be connected with receiving end.

The utility model calculates the electromagnetic radiation safe distance of the corresponding national standard of wireless energy transfer system by gathering voltage or the electric current of transmitting terminal and output terminal, will send early warning signal by the light early warning system when surpassing limiting distance,

Compared with prior art, the utility model is simple to operation, practical; Occupation during it is used wireless energy transfer system and the electromagnetic radiation security protection of environment possess directiveness.

Description of drawings

Fig. 1 is the connection layout of the utility model and wireless energy transfer system;

Fig. 2 is the wireless energy transfer wiring diagram of wireless energy transfer system among the embodiment;

Fig. 3 is the synoptic diagram of the transmitting coil (receiving coil) of wireless energy transfer system among the embodiment;

Fig. 4 is the induced electric field synoptic diagram of wireless energy transfer system among the embodiment.

Fig. 5 is the workflow diagram of Calculation of Safety Distance module in the utility model.

Embodiment

The utility model is described in further detail below in conjunction with embodiment shown in the drawings.

The utility model comprises electric current and voltage acquisition module, Calculation of Safety Distance module, the light early warning system that connects successively; The electric current and voltage acquisition module respectively with wireless energy transfer system in transmitting terminal be connected with receiving end.

Wireless energy transfer system among the embodiment comprises transmitting terminal and receiving end, and transmitting terminal comprises signal generator and transmitting coil, and receiving end comprises receiving coil; The internal resistance of transmitting coil, inductance, capacitance equate with internal resistance, inductance, the capacitance of receiving coil respectively; Transmitting coil and receiving coil are made on hollow skeleton by lead is evenly close, and the center of circle of transmitting coil and receiving coil is positioned on the same axis by the axis of skeleton; The cross section of lead is circular; Lead is the multiply enameled wire.

Below Calculation of Safety Distance process of the present utility model is elaborated:

I, mathematics computing model

Based on the wireless energy transfer wiring diagram of resonance coupling as shown in Figure 2, the equivalent electrical circuit of transmitting terminal comprises signal generator power supply AC, the transmitting coil internal resistance R of series connection ₁, the transmitting coil inductance L ₁With the transmitting coil capacitor C ₁, the equivalent electrical circuit of receiving end comprises series connection receiving coil internal resistance R ₂, the receiving coil inductance L ₂With the receiving coil capacitor C ₂, produce and the corresponding electric energy of signal generator power supply AC.Transmitting coil internal resistance and receiving coil internal resistance equate to be R=R among the figure ₁=R ₂, transmitting coil inductance and receiving coil inductance equate to be L=L ₁=L ₂, transmitting coil electric capacity and receiving coil electric capacity equate to be C=C ₁=C ₂The input voltage that makes circuit is u _i(t), output voltage is u ₀(t), set up mathematical model as shown in the formula (t represents the time, T for receiving end (secondary) ₁, T ₂Be time constant):

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

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

To the following formula both sides get Laplace change the complex field model, complex variable is labeled as s:

LCs ²u ₀(s)+RCsu(s)+u ₀(s)＝u _i(s) (3)

$\frac{u_0\left(s\right)}{u_i\left(s\right)}=\frac{1}{\mathrm{LC}{s}^2+\mathrm{RCs}+1}=\frac{\frac{1}{\mathrm{LC}}}{s^2+\frac{\mathrm{RC}}{\mathrm{LC}}s+\frac{1}{\mathrm{LC}}}=\frac{{{\mathrm{\ω}}_n}^2}{s^2+2\mathrm{\ξ}{\mathrm{\ω}}_{n}s+{{\mathrm{\ω}}_n}^2}---\left(4\right)$

Formula (4) is system transter, and then the amplitude-frequency function is:

A(ω)＝|G(jω)| (5)

Amplitude versus frequency characte A (ω) is that input amplitude and output amplitude are to the function of frequencies omega in the formula (5); G (j ω) is stable state output sinusoidal signal and the plural number ratio of importing sinusoidal signal under zero initial strip, also is the function of frequencies omega.

The system damping ratio is $\mathrm{\ξ}=\frac{R\sqrt{C}}{2\sqrt{L}}---\left(6\right)$

Resonance frequency is ${\mathrm{\ω}}_o=\frac{1}{\sqrt{\mathrm{LC}}}---\left(7\right)$

II, computing method model

Coil in the wireless energy transfer system is evenly close around lead, and the cross section of coiling is circular.Its structure as shown in Figure 3, equal densely packed coil structures of Cai Yonging, the resistance value of densely packed coil are calculated as follows that (wherein the coiling radius is r, and winding wire resistivity is ρ ₀, section radius is a, the number of turn is N, μ ₀For permeability of vacuum is 4 π x10 ^-7H/m, lead is D and D=2aN along axial length).The densely packed coil coiling center of circle is that any point P is the Χ place on the axial line in the accompanying drawing 3, and length is the monobasic section of dx on the line taking circle, is approximately a circular electric current then, and its electric current is

dI＝nIdx (8)

N is the coil turn on the unit length in the formula, by being easy to get in the accompanying drawing 2:

$n=\frac{N}{2\mathrm{aN}}=\frac{1}{2a}---\left(9\right)$

Magnetic moment is

$\mathrm{dm}=\mathrm{SdI}=\mathrm{\π}{r}^2\mathrm{dI}=\frac{\mathrm{\π}{r}^2}{2a}\mathrm{Idx}---\left(10\right)$

Coil be circular coiling then

∮dl=2πr (11)

Magnetic field is on the axis

The magnetic moment of closed hot-wire coil

m＝IS＝Iπr ² (13)

Then got by formula (11), (12), (13):

$B=\frac{{\mathrm{\μ}}_{0}m}{2\mathrm{\π}{r_1}^3}---\left(14\right)$

Can be got by formula (10), (14):

$\mathrm{dB}=\frac{{\mathrm{\μ}}_0{r}^2}{4a{r_1}^3}\mathrm{Idx}---\left(15\right)$

Can try to achieve as shown in FIG.

r＝r ₁sinθ (16)

x＝rcotθ (17)

$\mathrm{dx}=\frac{-r}{{\sin }^2\mathrm{\θ}}\mathrm{d\θ}---\left(18\right)$

Got by formula (15), (16), (17), (18):

$\mathrm{dB}=\frac{{\mathrm{\μ}}_0{r}^2}{4a{\left(\frac{r}{\sin \mathrm{\θ}}\right)}^3}\left(\frac{-r}{{\sin }^2\mathrm{\θ}}\right)\mathrm{d\θ}=\frac{-{\mathrm{\μ}}_{0}I\sin \mathrm{\θ}}{4a}\mathrm{d\θ}---\left(19\right)$

Therefore,

$B=\∫\mathrm{dB}=-{\∫}_{{\mathrm{\θ}}_1}^{{\mathrm{\θ}}_2}\frac{{\mathrm{\μ}}_{0}I\sin \mathrm{\θ}}{4a}\mathrm{d\θ}=\frac{{\mathrm{\μ}}_{0}I}{4a}(\cos {\mathrm{\θ}}_2-\cos {\mathrm{\θ}}_1)---\left(20\right)$

Here therefore the air core coil of Cai Yonging has

$H=\frac{B}{{\mathrm{\μ}}_0}=\frac{I}{4a}(\cos {\mathrm{\θ}}_2-\cos {\mathrm{\θ}}_1)---\left(21\right)$

θ in the formula ₁, θ ₂Value and accompanying drawing 2 in the P position of ordering relevant, also can be converted into P to A ₁The relation of the distance of point might as well be established P to A ₁The distance of point is y, then has:

$\cos {\mathrm{\θ}}_2=\frac{y+D}{\sqrt{{(y+D)}^2+r^2}}---\left(22\right)$

$\cos {\mathrm{\θ}}_1=\frac{y}{\sqrt{y^2+r^2}}---\left(23\right)$

In wireless energy transfer system, system needs near the tuning-points of work, and when system's generation resonance, it is R that only there is real part in the impedance in the circuit, and then electric current is:

$I=\frac{U_i}{R}---\left(24\right)$

Had by Faraday's electromagnetic induction law:

Because the symmetry in magnetic field, the electric field line of variation magnetic field institute induced Electric Field Produced are outer in coil all to be the concentric circles (order with the plan range in the center of circle be Z) coaxial with coil, as shown in Figure 4:

Get counterclockwise electric field line as the closed-loop path, the loop direction is identical with the direction of electric field intensity, so ∮ _LEds=∮ _LEds=2 π zE (26)

$E=-\frac{1}{2\mathrm{\πz}}\underset{s}{\∫\∫}\frac{\∂B}{\∂t}\·\mathrm{dS}---\left(27\right)$

According to the right-handed helix rule, the direction vertical screen of area that the loop surrounds is outside, the dB/dt vertical screen inwards, both directions are opposite.

Z〉during r, have only magnetic field is arranged in the solenoid, can get induced electric field and be:

$E=\frac{r^2}{2z}\frac{\mathrm{dB}}{\mathrm{dt}}---\left(28\right)$

The induced electric field intensity that pipe is outer and distance between the two are inversely proportional to.And when z≤r, induced electric field is:

$E=\frac{z}{2}\frac{\mathrm{dB}}{\mathrm{dt}}---\left(29\right)$

Induced electric field intensity in the pipe is directly proportional with distance.

Z〉during r, by formula (21), (28):

$E=\frac{r^2}{2z}\·\frac{{\mathrm{\μ}}_0}{4a}(\cos {\mathrm{\θ}}_2-\cos {\mathrm{\θ}}_1)\·\mathrm{dI}/\mathrm{dt}---\left(30\right)$

It is the sine ac power supply of w that native system adopts frequency, during resonance phase angle be 0 ° then:

Bringing formula (30) into gets:

In like manner can get, when z≤r,

Then can be calculated magnetic field and the electric field intensity of pickup coil axial distance each point by following formula (21), (32), (33).

According to the regulation of State Bureau of Environmental Protection about electromagnetic radiation protection, corresponding different occupation and the public of different frequency section shone limit value, and simultaneously, when having a plurality of radiator, the field mean value sum of amount parameter in arbitrarily continuous 6min of its electromagnetic radiation field should satisfy

$\underset{i}{\mathrm{\Σ}}\underset{j}{\mathrm{\Σ}}\frac{A_{i,j}}{{B^{,}}_{i,j,L}}\≤1---\left(34\right)$

A in the formula _{I, j}It is the radiation level of i radiator j frequency range radiation; B ' _{I, j, L}Corresponding to the electromagnetic radiation defined of j frequency range irradiation limit value (comprising electric field intensity and magnetic field intensity).

The near region alternating magnetic field is the media of wireless energy transfer, thus this patent mainly consider the near field region safe distance computational problem.Apart from being the effective coverage of the wireless transmission of electricity of resonance manifold type in hub of a spool λ/2 π, exceeded this and just can not transmit energy apart from transmission system.According to

$\mathrm{\λ}=\frac{c}{f}---\left(35\right)$

λ is electromagnetic wavelength in the formula, and c is velocity of wave, and f is frequency.For example its near field region scope of wireless power transmission systems for 10MHz is 4.77m, is 47.7m for its near field region scope of wireless power transmission systems of 1MHz.Determine that according to following formula (35) system is after the near field region scope, by excitation power supply value and formula (21), (32), each known parameters on (33) the right and the center of circle axial distance that formula (34) can calculate the pickup coil of magnetic field and electric field safety limit correspondence respectively of system, namely be respectively the safe distance of magnetic field and electric field.

III, system architecture

When the electric current and voltage acquisition module collects the variation of infinite energy transmission system electric current and voltage, the Calculation of Safety Distance module will be calculated its electromagnetic radiation and whether surpass limit value; If when surpassing, will send early warning signal by the light early warning system.

Claims (1)

1. the electromagnetic radiation safety pre-warning system of a wireless energy transfer system is characterized in that: comprise the electric current and voltage acquisition module, Calculation of Safety Distance module, the light early warning system that connect successively; The electric current and voltage acquisition module respectively with wireless energy transfer system in transmitting terminal be connected with receiving end.

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