CN205725177U - WPT optimum capacitance based on individual pen circle PCB coil selects device - Google Patents

Abstract

The utility model discloses a kind of WPT optimum capacitance based on individual pen circle PCB coil and select device, receive circuit including resonance type wireless electric energy transmission circuit and resonant mode radio energy；Resonance type wireless electric energy transmission circuit includes driving power supply V_S, drive loss of power R_S, send coil additional electric capacity C₁, send coil parasitic capacitance C₃, send coil loss resistance R₁And first self-induction L₁；Resonance type wireless electric energy receives circuit and includes loading R_L, receiving coil additional electric capacity C₂, receiving coil parasitic capacitance C₄, receiving coil loss resistance R₂And second self-induction L₂；This utility model can quickly obtain frequency corresponding to optimum efficiency and corresponding capacitance, thus complete design.

Description

WPT optimum capacitance based on individual pen circle PCB coil selects device

Technical field

This utility model belongs to wireless power transmission field, is specifically related to a kind of WPT based on individual pen circle PCB coil Excellent capacitance selection device.

Background technology

In many occasions, the power supply of electronic device uses wired power supply or battery inconvenience of powering even may.As In a large amount of embedded material of wireless senser in intelligent building, body of wall, work as running down of battery, it is impossible to change electricity battery；Agriculture in the wild For detecting the wireless senser of crop growth in industry, change battery and to spend a large amount of manpower and materials；In implantable medical The medical device implanted, changes battery and may bring painful and risk etc. to human body.Wireless power is to solve this problem One of approach.

Resonance type wireless electric energy transmission system, makes it by electric capacity on electric energy transmitting terminal and the coils connected in series of receiving terminal or parallel connection Each self-forming resonance, and resonant frequency is arranged to identical.Fig. 1 is a typical example, all uses at transmitting terminal and receiving terminal The two coil resonance type wireless electric energy transmission system of series resonance form, including: the drive circuit of transmitting terminal, send coil L₁, Series capacitance C needed for resonance is formed with sending coil₁, receiving coil L₂, form the series capacitance needed for resonance with receiving coil C₂, and rectification circuit and load etc..Its basic functional principle is: drive circuit produces the alternating current of certain power, its frequency Identical with the resonant frequency of transmitting terminal, receiving terminal, this alternating current is through sending the transmission of the electromagnetic coupled between coil and receiving coil To receiving terminal, and rectified circuit changes into unidirectional current, powering load or energy storage.Compared to disresonance type wireless power transmission system System, resonance type wireless electric energy transmission system has bigger efficiency of transmission under moderate distance.

In existing design, send and receiving coil between distance, coil size generally by concrete application scenarios Determine, for reaching maximum efficiency of transmission, how to the shape of coil, size, resonant capacitance size and the work thus determined Working frequency is designed the key issue being to need to solve.

Summary of the invention

This utility model is for for the deficiencies in the prior art, it is proposed that a kind of WPT based on individual pen circle PCB coil is Excellent capacitance selection device.

In this utility model the technical scheme is that resonance type wireless electric energy transmitting procedure, removing drive circuit After the energy loss that spontaneous, rectification circuit is spontaneous, electric energy efficiency of transmission is by the coefficient of coup between coil, the loss on coil certainly Fixed.Generally, the quality factor of electric capacity are the highest, and its loss can be ignored.

WPT optimum capacitance based on individual pen circle PCB coil selects device, including resonance type wireless electric energy transmission circuit and Resonance type wireless electric energy receives circuit；

Resonance type wireless electric energy transmission circuit includes driving power supply V_S, drive loss of power R_S, send the additional electric capacity of coil C₁, send coil parasitic capacitance C₃, send coil loss resistance R₁And first self-induction L₁；

Drive power supply V_SOne end with drive loss of power R_SOne end connect, drive loss of power R_SThe other end with send out Sending coil additional electric capacity C₁One end connect, send coil additional electric capacity C₁The other end with send coil loss resistance R₁One End, transmission coil parasitic capacitance C₃One end connect, send coil loss resistance R₁The other end and the first self-induction L₁One end even Connect, the first self-induction L₁The other end with send coil parasitic capacitance C₃The other end, drive power supply V_SThe other end connect；

Resonance type wireless electric energy receives circuit and includes loading R_L, receiving coil additional electric capacity C₂, receiving coil parasitic capacitance C₄, receiving coil loss resistance R₂And second self-induction L₂；

Receiving coil loss resistance R₂One end and receiving coil additional electric capacity C₂One end, receiving coil parasitic capacitance C₄ One end connect, receiving coil loss resistance R₂The other end and the second self-induction L₂One end connect, the second self-induction L₂The other end With receiving coil parasitic capacitance C₄One end, load R_LOne end connect, receiving coil additional electric capacity C₂The other end with load R_L The other end connect.

Described transmission coil and receiving coil are individual pen circle PCB coil, and its cross section is rectangle.

The method of described selection optimum capacitance value comprises the following steps:

1) coil parasitic capacitance C is sent₃With receiving coil parasitic capacitance C₄The additional electric capacity of coil is being sent by dummy coil C₁Electric capacity C additional with receiving coil₂Time formed series resonance frequency ω₁With self-resonant frequency ω₂Obtain.Series resonance frequency ω₁With self-resonant frequency ω₂Expression formula be respectively as follows:

${\mathrm{\ω}}_1=\frac{1}{\sqrt{L_1(C_1+C_3)}}$

${\mathrm{\ω}}_2=\frac{1}{\sqrt{L_1{C}_3}}$

Therefore, parasitic capacitance C is tried to achieve₃For:

$C_3=\left(\frac{{\mathrm{\ω}}_1^2}{{\mathrm{\ω}}_2^2-{\mathrm{\ω}}_1^2}\right)C_1$

In like manner, parasitic capacitance C of receiving coil is tried to achieve₄For:

$C_4=\left(\frac{{\mathrm{\ω}}_1^2}{{\mathrm{\ω}}_2^2-{\mathrm{\ω}}_1^2}\right)C_2$

2) loss resistance sending coil and receiving coil is:

$R=\frac{l}{\mathrm{\σ}wt}{\[1+{\left(\frac{f}{f_1}\right)}^2+{\left(\frac{f}{f_0}\right)}^5\]}^{0.1}$

$f_1=\frac{\mathrm{\π}}{2\mathrm{\μ}\mathrm{\σ}wt}$

$f_0=\frac{{\mathrm{\π}}^2}{{\mathrm{\σ\μt}}^2}\[K\left(\sqrt{\frac{w^2-t^2}{w^2}}\right)\]$

$f=\frac{1}{2\mathrm{\π}\sqrt{L_1(C_1+C_3)}}=\frac{1}{2\mathrm{\π}\sqrt{L_2(C_2+C_4)}}$

Wherein l is loop length, and w is coil section width, and t is coil section height, and σ is electrical conductivity, and μ is magnetic conductance Rate, K (+) represent Kelvin function.

3) self-induction sending coil is:

$L_1=\mathrm{\μ}a\[\ln \left(\frac{8a}{d}\right)*(1+\frac{3d^2}{16a^2})-(2+\frac{d^2}{16a^2})\]$

The self-induction of receiving coil is:

$L_2=\mathrm{\μ}b\[\ln \left(\frac{8b}{d}\right)*(1+\frac{3d^2}{16b^2})-(2+\frac{d^2}{16b^2})\]$

$\begin{array}{c}\ln d=\ln \sqrt{w^2+t^2}-\frac{1}{6}\frac{w^2}{t^2}\ln \sqrt{1+\frac{t^2}{w^2}}-\frac{1}{6}\frac{t^2}{w^2}\ln \sqrt{1+\frac{w^2}{t^2}}\\ +\frac{2}{2}\frac{w}{t}{\tan }^{-1}\frac{t}{w}+\frac{2}{3}\frac{t}{w}{\tan }^{-1}\frac{w}{t}-\frac{25}{12}\end{array}$

Wherein a is transmitting coil radius, and b is receiving coil radius, and w, t are coil section width and height respectively.

4) sending mutual inductance between coil and receiving coil is:

$M=\frac{{\mathrm{\μ}}_0{\mathrm{\πa}}^2{b}^2}{2{(a^2+b^2+z^2)}^{3/2}}(1+\frac{15}{32}{\mathrm{\γ}}^2+\frac{315}{1024}{\mathrm{\γ}}^4)$

WhereinA, b are transmitting coil and receiving coil radius, and z is spacing between two coils.

5) resonant radio can transmit system equivalent circuit calculate system power efficiency of transmission be:

$\mathrm{\η}=\frac{R_L}{R_2+R_L+R_1\frac{|Z_2{|}^2}{{\left(\mathrm{\ω}M\right)}^2}}$

Wherein, ω=2 π f is operating angle frequency, Z₂For receiving coil impedance, j represents imaginary part, and its value is

$Z_2=\frac{1}{{\mathrm{j\ωC}}_2}+\frac{R_2+{\mathrm{j\ωL}}_2}{1-{\mathrm{\ω}}^2{L}_2{C}_4+{\mathrm{j\ωC}}_4{R}_2}+R_L$

Owing to system works at a resonant condition, now resonant frequency is

$f=\frac{1}{2\mathrm{\π}\sqrt{L_1(C_1+C_3)}}=\frac{1}{2\mathrm{\π}\sqrt{L_2(C_2+C_4)}}$

And parasitic capacitance is fixing, it is seen then that efficiency is relevant to additional electric capacity, due to loss resistance R₁、R₂Increase with frequency And increase, therefore efficiency is not the monotonic function of additional electric capacity, thus under resonant mode working condition, there is the resonance of optimum Capacitance.Above-mentioned resistance, inductance, mutual inductance expression formula and parasitic capacitance value are substituted in efficiency expression formula, the parsing of efficiency can be obtained Solve expression formula.By it with mathematical tool software such as Matlab, it is possible to be quickly found out optimum additional capacitance, it is thus possible to obtain Excellent operating frequency.

This utility model has the advantage that

For the wireless power transmission system sent and receiving coil is the circle circular coil that PCB printed circuit board realizes System, based on mutual inductance between coil, self-induction of loop, the analytical model of coil resistance, gives the Explicit Expression formula of efficiency.Imitate based on this The Explicit Expression formula of rate, it is possible to quickly obtain frequency corresponding to optimum efficiency and corresponding capacitance, thus complete design.

Accompanying drawing explanation

Fig. 1 is structure principle chart during resonance type wireless electric energy transmission system employing series capacitance formation resonance.Including: send out The drive circuit of sending end, sends coil L₁, form series capacitance C needed for resonance with sending coil₁, receiving coil L₂, with reception Coil forms series capacitance C needed for resonance₂, parasitic capacitance C₃、C₄And rectification circuit and load.

Fig. 2 is the equivalent circuit of Fig. 1.V in figure_SFor equivalent AC voltage source, R_SFor the output resistance of alternating-current voltage source, R₁ For sending the loss resistance of coil, R₂For the loss resistance of receiving coil, R_LFor equivalent load, L₁For sending self-induction of loop, C₁For Transmitting terminal series resonant capacitance, L₂For receiving coil self-induction, C₂For receiving terminal series resonant capacitance, C₃、C₄For parasitic capacitance.

Fig. 3 is the value of calculation that in embodiment 1, loss resistance changes with frequency.

Fig. 4 is embodiment 1 China and foreign countries Z when adding electric capacity₁₁The finite element electromagnetic simulation software simulation result of parameter.

Fig. 5 is the efficiency obtained in embodiment 1 result when inserting different resonant capacitance.

Detailed description of the invention

Below in conjunction with accompanying drawing 1, accompanying drawing 2 and embodiment, the utility model is described in further detail.

WPT optimum capacitance based on individual pen circle PCB coil selects device, including resonance type wireless electric energy transmission circuit and Resonance type wireless electric energy receives circuit；

Resonance type wireless electric energy transmission circuit includes driving power supply V_S, drive loss of power R_S, send the additional electric capacity of coil C₁, send coil parasitic capacitance C₃, send coil loss resistance R₁And first self-induction L₁；

Drive power supply V_SOne end with drive loss of power R_SOne end connect, drive loss of power R_SThe other end with send out Sending coil additional electric capacity C₁One end connect, send coil additional electric capacity C₁The other end with send coil loss resistance R₁One End, transmission coil parasitic capacitance C₃One end connect, send coil loss resistance R₁The other end and the first self-induction L₁One end even Connect, the first self-induction L₁The other end with send coil parasitic capacitance C₃The other end, drive power supply V_SThe other end connect；

Resonance type wireless electric energy receives circuit and includes loading R_L, receiving coil additional electric capacity C₂, receiving coil parasitic capacitance C₄, receiving coil loss resistance R₂And second self-induction L₂；

Receiving coil loss resistance R₂One end and receiving coil additional electric capacity C₂One end, receiving coil parasitic capacitance C₄ One end connect, receiving coil loss resistance R₂The other end and the second self-induction L₂One end connect, the second self-induction L₂The other end With receiving coil parasitic capacitance C₄One end, load R_LOne end connect, receiving coil additional electric capacity C₂The other end with load R_L The other end connect.

Described transmission coil and receiving coil are individual pen circle PCB coil, and its cross section is rectangle.

The transmission of embodiment 1: resonance type wireless electric energy transmission system is identical with receiving coil, and radius is 10cm, the number of turns Being a circle, print with PCB and realize, the width of wire is 2mm, and thickness is 0.018mm.Send that coil is parallel with receiving coil puts Put, spacing 10cm between central shaft identical two coils.Using computing formula described in the utility model, being calculated self-induction is 690nH, Mutual inductance is 49nH, and the result of calculation that loss resistance changes with frequency is as shown in Figure 3.When Fig. 4 is additional electric capacity 60pF, HFSS emulates The Z obtained₁₁Parameter, is self-resonant frequency at crest, thus calculate parasitic capacitance is 0.75pF.By above-mentioned analytical Calculation value, generation Enter in efficiency expression formula, it is possible to quickly obtain the efficiency result of variations with the different electric capacity of insertion, efficiency therefrom can be found maximum Time corresponding electric capacity.For verifying the effectiveness of result of calculation, result of calculation and HFSS simulation result are compared (see Fig. 5), By calculating and simulation result is known, emulating the optimum capacitance value obtained in this example is between 2pF to 4pF, calculated Excellent capacitance is also between 2pF to 4pF.In actual applications, the capacitance that use is properly capable of near optimum point Reach optimum efficiency of transmission.

Visible, method described in the utility model can be quickly found out coupling optimal capacitance.

Claims (1)

1. WPT optimum capacitance based on individual pen circle PCB coil selects device, it is characterised in that: include resonance type wireless electric energy Transmission circuit and resonant mode radio energy receive circuit；

Resonance type wireless electric energy transmission circuit includes driving power supply V_S, drive loss of power R_S, send coil additional electric capacity C₁, send out Sending coil parasitic capacitance C₃, send coil loss resistance R₁And first self-induction L₁；

Drive power supply V_SOne end with drive loss of power R_SOne end connect, drive loss of power R_SThe other end with send line Enclose additional electric capacity C₁One end connect, send coil additional electric capacity C₁The other end with send coil loss resistance R₁One end, send out Sending coil parasitic capacitance C₃One end connect, send coil loss resistance R₁The other end and the first self-induction L₁One end connect, the One self-induction L₁The other end with send coil parasitic capacitance C₃The other end, drive power supply V_SThe other end connect；

Resonance type wireless electric energy receives circuit and includes loading R_L, receiving coil additional electric capacity C₂, receiving coil parasitic capacitance C₄, connect Take-up circle loss resistance R₂And second self-induction L₂；

Receiving coil loss resistance R₂One end and receiving coil additional electric capacity C₂One end, receiving coil parasitic capacitance C₄One End connects, receiving coil loss resistance R₂The other end and the second self-induction L₂One end connect, the second self-induction L₂The other end with connect Take-up circle parasitic capacitance C₄One end, load R_LOne end connect, receiving coil additional electric capacity C₂The other end with load R_LAnother One end connects；

Described transmission coil and receiving coil are individual pen circle PCB coil, and its cross section is rectangle.