CN112886716B - Integrated electromagnetic coupling mechanism and electric energy transmitting end, receiving end and transmission system thereof - Google Patents
Integrated electromagnetic coupling mechanism and electric energy transmitting end, receiving end and transmission system thereof Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
- H02J50/10—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
- H02J50/005—Mechanical details of housing or structure aiming to accommodate the power transfer means, e.g. mechanical integration of coils, antennas or transducers into emitting or receiving devices
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
- H02J50/05—Circuit arrangements or systems for wireless supply or distribution of electric power using capacitive coupling
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
- H02J50/10—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling
- H02J50/12—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling of the resonant type
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Abstract
The invention relates to the technical field of electromagnetic coupling, and particularly discloses an integrated electromagnetic coupling mechanism, and an electric energy transmitting end, an electric energy receiving end and a transmission system thereof 1 A first dielectric, a first inner electromagnetic pole P 2 And a second inner electromagnetic pole P arranged in a stacked manner 4 A second dielectric, a second external electromagnetic pole P 3 First inner electromagnetic pole P 2 And a second inner electromagnetic pole P 4 Are opposite and at a distance d t Electromagnetic pole P 1 、P 2 、P 4 And P 3 Are formed by spirally winding square metal lines with consistent specifications in the same direction. The electric energy transmission system provided by the invention is based on the integrated electromagnetic coupling mechanism, the circuit theory and the mutual inductance coupling theory, simplifies the equivalent circuit of the coupling mechanism, establishes a system alternating current impedance model, realizes self-compensation of the coupling mechanism by analyzing and calculating the relation between the electric parameters of the coupling mechanism, and provides the working condition of the zero input impedance angle of the system.
Description
Technical Field
The invention relates to the technical field of electromagnetic coupling, in particular to an integrated electromagnetic coupling mechanism, an electric energy transmitting end of the integrated electromagnetic coupling mechanism, an electric energy receiving end of the integrated electromagnetic coupling mechanism and an electric energy transmission system of the integrated electromagnetic coupling mechanism.
Background
The Wireless Power Transfer (WPT) is an electric energy transmission technology which comprehensively utilizes the Power electronic technology and the modern control theory and realizes no direct electric contact through soft media (magnetic field, electric field, microwave, laser and the like), and the technology effectively solves the problems of unsafe and inflexible electric energy access of the traditional electric equipment contact Power supply mode. At present, researches on a Magnetic-field Coupled Wireless Power Transfer (MC-WPT) technology and an Electric-field Coupled Wireless Power Transfer (EC-WPT) technology are widely carried out, wherein the two technologies mainly depend on an electromagnetic field theory to construct an Electric energy transmission channel, and are combined with technologies such as Power electronic transformation, resonance compensation, control and communication to realize safe and effective Wireless transmission of Electric energy. From the existing literature, the research on the MC-WPT technology is more mature, the application is wider, and the MC-WPT technology is related to the aspects of electric automobiles, biological medicine, consumer electronics and the like. In recent years, the EC-WPT system coupling mechanism has attracted attention due to the characteristics of simplicity, lightness, thinness, low cost, capability of transmitting energy through metal and the like.
In order to improve WPT system performance, the existing literature generally adopts two basic approaches: 1) Improving the compensation structure and the parameter resonance relation thereof; 2) The electromagnetic coupling structure is improved and optimized. The first mode has obvious effects on the aspects of improving the transmission power of the system, realizing constant voltage or constant current output, inhibiting higher harmonics, reducing input reactive components and the like, and the second mode has advantages on the aspects of improving the efficiency and power density of the system, improving the offset resistance of the system, maintaining the safety of the system, reducing the cost of the system and the like.
For an EC-WPT system, the coupling mechanism can be generally equivalent to two coupling capacitors connected in series, or six cross-coupling capacitors. In order to improve the system performance, the reactive power is compensated by adopting a series single inductor mode in the past. However, for long-distance (centimeter or above) transmission application, because the coupling capacitance is too small, the complete reactive compensation can be realized only by connecting a large inductor in series. The introduction of large inductance increases the system size and the inductance loss, resulting in a too low system efficiency. In addition, because the single inductance compensation structure only adopts series resonance, for high-power electric energy transmission, a coupling mechanism needs to bear high voltage stress, and the safety of the system is questioned. For MC-WPT (multi-carrier wave-programmable) systems, in order to improve system performance, previous researches are carried out by adopting four classical compensation structures to carry out reactive compensation on self-inductance of a transmitting end and a receiving end of a coupling mechanism [1] . However, the four-large structure also has a plurality of problems, for example, the compensation capacitance of the receiving end of the P/S and P/P structure is related to the load size, which has a great limitation in practical application [1] (ii) a The inversion output voltage of the S/S compensation structure is very sensitive to load variation [2] (ii) a The output voltage of the S/P compensation structure at the gain intersection is approximately inversely proportional to the coupling coefficient, which is not suitable for cases where the coupling coefficient varies over a large range [3] 。
In response to the above problems of EC-WPT and MC-WPT systems, various composite resonance compensation networks, such as LCL (inductor-capacitor-inductor), LCC (inductor-capacitor), CLC (capacitor-inductor-capacitor), and LCLC (inductor-capacitor-inductor-capacitor), etc., have been proposed and improved one after another. In order to further improve the performance of the WPT system, experts make a lot of research around electromagnetic coupling mechanisms, and in view of the existing documents, for a single magnetic field coupling mechanism or electric field coupling mechanism, in order to improve the transmission distance of the WPT system and increase the output power and efficiency, a corresponding high-order compensation network is generally required to be added to the coupling mechanism. For the inductance-capacitance hybrid wireless power transmission system, the magnetic coupling mechanism is generally formed by litz wire winding, the electric field coupling mechanism is generally formed by an aluminum or copper metal plate, and a corresponding high-order compensation network is also configured for the electric field coupling mechanism. Due to the introduction of the litz coil and the high-order compensation network, the volume and the weight of the system are increased, the cost of the system is increased, the power density of the system is greatly reduced, and the application and the popularization of the WPT technology are seriously restricted.
Reference documents:
[1]Chwei-Sen Wang,G.A.Covic and O.H.Stielau,"Power transfer capability and bifurcation phenomena of loosely coupled inductive power transfer systems,"in IEEE Transactions on Industrial Electronics,vol.51,no.1,pp.148-157,Feb.2004.
[2]W.Zhang,S.Wong,C.K.Tse and Q.Chen,"Design for Efficiency Optimization and Voltage Controllability of Series–Series Compensated Inductive Power Transfer Systems,"in IEEE Transactions on Power Electronics,vol.29,no.1,pp.191-200,Jan.2014.
[3]J.Hou,Q.Chen,K.Yan,X.Ren,S.Wong and C.K.Tse,"Analysis and control of S/SP compensation contactless resonant converter with constant voltage gain,"2013IEEE Energy Conversion Congress and Exposition,Denver,CO,2013,pp.2552-2558.
disclosure of Invention
The invention provides an integrated electromagnetic coupling mechanism, an electric energy transmitting end, an electric energy receiving end and a transmission system thereof, and solves the technical problems that: for a single electric field coupling mechanism, the introduction of the litz coil and the high-order compensation network in the prior art leads to the increase of the volume and the weight of the system, the increase of the cost of the system and the great reduction of the power density of the system.
To solve the above technical problem, the present invention provides an integrated electromagnetic coupling mechanism, which includes a first outer electromagnetic pole P arranged in a stacked manner 1 A first dielectric, a first inner electromagnetic pole P 2 And a second inner electromagnetic pole P arranged in a stacked manner 4 A second dielectric, a second external electromagnetic pole P 3 Said first inner electromagnetic pole P 2 And the second inner electromagnetic pole P 4 Are opposite and spaced by a distance d t The first external magnetic pole P 1 The first inner electromagnetic pole P 2 Station, stationThe second inner electromagnetic pole P 4 And said second outer electromagnetic pole P 3 Are formed by spirally winding square metal lines with consistent specifications in the same direction.
Preferably, the first external electromagnetic pole P 1 And the second outer electromagnetic pole P 3 Uniform size, the first inner electromagnetic pole P 2 And the second inner electromagnetic pole P 4 The dimensions are uniform and the thickness of the first dielectric and the thickness of the second dielectric are equal.
Preferably, the first external electromagnetic pole P 1 The first inner electromagnetic pole P 2 The second inner electromagnetic pole P 4 And said second outer electromagnetic pole P 3 Are all wound into a plane spiral square electromagnetic pole.
Preferably, the parameters of any one of the planar square spiral electromagnetic poles satisfy:
D out ＝D in +2w+(w+s)(2N-1)
wherein D is out 、D in The outer diameter and the inner diameter are respectively, w is the width of the square metal line, s is the distance between two adjacent turns of the square metal line, and N is the number of turns.
The invention provides an integrated electromagnetic coupling mechanism, which adopts a planar coil type coupling electromagnetic pole formed by spirally winding a square metal wire, and four electromagnetic poles are stacked to form the electromagnetic coupling mechanism, so that the self-inductance value of a coil and the mutual inductance value between the coils can be ensured, the cross-coupling capacitance between the electromagnetic poles can be increased, the electric field coupling coefficient can be increased, the electric energy transmission quality can be improved by fully utilizing the parasitic capacitance characteristic of the coil neglected in the previous research, the influence of the skin effect on an electric energy transmission system can be effectively overcome, and the ohmic loss of the coupling mechanism can be reduced.
The invention also provides an electric energy transmitting end of the integrated electromagnetic coupling mechanism, which is provided with a half-bridge inverter circuit and a transmitting end electromagnetic pole, wherein the transmitting end electromagnetic pole comprises a first external electromagnetic pole P in the integrated electromagnetic coupling mechanism 1 A first inner electromagnetic pole P 2 The low potential end of the half-bridge inverter circuit is connected with the first external electromagnetic pole P 1 The high potential end of the half-bridge inverter circuit is connected with the first inner electromagnetic pole P 2 The same name end of (c).
The invention also provides an electric energy receiving end of the integrated electromagnetic coupling mechanism, which is provided with a receiving end electromagnetic pole and a rectifying and filtering circuit, wherein the receiving end electromagnetic pole comprises a second outer electromagnetic pole P in the integrated electromagnetic coupling mechanism 3 A second inner electromagnetic pole P 4 The low potential end of the rectifying and filtering circuit is connected with the second outer electromagnetic pole P 3 The high potential end of the rectifying and filtering circuit is connected with the second inner electromagnetic pole P 4 The synonym end of (c).
The invention also provides an electric energy transmission system of the integrated electromagnetic coupling mechanism, which is formed by the electric energy transmitting end and the electric energy receiving end.
For this system, preferably, the first external magnetic pole P 1 The first inner electromagnetic pole P 2 The second inner electromagnetic pole P 4 The second outer electromagnetic pole P 3 The design of (2) satisfies:
when the temperature is higher than the set temperature
When, is greater or less>
Wherein, ω =2 π f is the system operating angular frequency, f is the system operating frequency, C A ＝C 1 +2C M ，
M ij Is an electromagnetic pole P i And an electromagnetic pole P j Mutual inductance between, C ij Is an electromagnetic pole P i And an electromagnetic pole P j Formed coupling capacitance, L i Is an electromagnetic pole P i I, j =1,2,3,4.
Or, the first external electromagnetic pole P 1 The first inner electromagnetic pole P 2 The second inner electromagnetic pole P 4 And the second outer electromagnetic pole P 3 The design of (2) satisfies:
when in use
When the temperature of the water is higher than the set temperature,
preferably, the system operating frequency is:
wherein the content of the first and second substances,
/>
the invention provides an electric energy transmission system of an integrated electromagnetic coupling mechanism, which is based on a circuit theory and a mutual inductance coupling theory (four electromagnetic poles have certain self-inductance and can generate cross coupling among the four electromagnetic poles to form cross mutual inductance and cross coupling capacitance), simplifies an equivalent circuit of the coupling mechanism, establishes a system alternating current impedance model, realizes self-compensation of the coupling mechanism by analyzing and calculating the relation among electrical parameters of the coupling mechanism, and provides working conditions of a Zero Phase Angle (ZPA) of the system. Compared with the prior art, the system adopts the integrated electromagnetic coupling mechanism, can effectively reduce the volume and the weight of the system, further reduces the cost and ensures the performance of the system.
Drawings
Fig. 1 is a 3D diagram of an integrated electromagnetic coupling mechanism provided in embodiment 1 of the present invention;
fig. 2 is a front view of an integrated electromagnetic coupling mechanism provided in embodiment 1 of the present invention;
FIG. 3 is a top view of a planar spiral square electromagnetic pole provided in embodiment 1 of the present invention;
FIG. 4 is an equivalent model diagram of the coupling mechanism shown in FIG. 1 or 2 provided in embodiment 1 of the present invention;
fig. 5 is an equivalent circuit topology diagram of an electric energy transmission system of an integrated electromagnetic coupling mechanism provided in embodiment 2 of the present invention;
FIG. 6 is a simplified model diagram of a pi type of the topology shown in FIG. 5 provided in embodiment 2 of the present invention;
FIG. 7 is a circuit equivalent diagram of the simplified model shown in FIG. 6 provided in embodiment 2 of the present invention;
FIG. 8 shows the coupling coefficient of the coupling mechanism according to the number of turns N of the inner electromagnetic pole copper foil according to embodiment 2 of the present invention in A graph of variation relationships of (2);
FIG. 9 shows the input impedance of the system provided by embodiment 2 of the present invention as a function of the number of turns N of the inner EMC foil in A graph of variation relationships of (2);
FIG. 10 shows the system operating frequency f according to embodiment 2 of the present invention 1 And f 2 Number of turns N of copper foil along with inner electromagnetic pole in And an equivalent load R eq A graph of variation relationships of (c);
FIG. 11 shows an electromagnetic pole P provided in embodiment 2 of the present invention 3 And P 4 Number of turns N of copper foil of inner electromagnetic pole along with voltage to earth in A graph of variation relationships of (2);
fig. 12 is a graph of the variation of the input impedance of the system and the operating frequency provided in embodiment 2 of the present invention;
FIG. 13 shows the system inverter output voltage (U) provided in embodiment 2 of the present invention in ) And an output current (I) in ) A waveform diagram of (a);
FIG. 14 shows the system output voltage (U) provided in embodiment 2 of the present invention out ) And an output current (I) out ) A waveform diagram of (a);
FIG. 15 shows an electromagnetic pole P provided in embodiment 2 of the present invention 1 、P 2 、P 3 、P 4 To ground voltage (U) P1 、U P2 、U P3 、U P4 ) A waveform diagram;
FIG. 16 shows an electromagnetic pole P provided in embodiment 2 of the present invention 1 、P 2 、P 3 、P 4 Current (I) of P1 、I P2 、I P3 、I P4 ) A waveform diagram;
FIG. 17 is a distribution diagram of an electric field intensity of a coupling mechanism provided in embodiment 2 of the invention;
fig. 18 is a magnetic field intensity distribution diagram of a coupling mechanism provided in embodiment 2 of the present invention.
Detailed Description
The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, which are given solely for the purpose of illustration and are not to be construed as limitations of the invention, including the drawings which are incorporated herein by reference and for illustration only and are not to be construed as limitations of the invention, since many variations thereof are possible without departing from the spirit and scope of the invention.
Example 1
As shown in fig. 1 to 3, in the present embodiment, unlike a coil wound with litz wires in the past research on an IPT system, and unlike a metal plate used as an electrode in the past research on a CPT system, an electromagnetic pole in the present embodiment is formed by spirally winding a square metal wire (a copper foil strip in the present embodiment) having a certain width, which can ensure a self-inductance value of the coil and a mutual inductance value between the coils, and can increase a cross-coupling capacitance between the electromagnetic poles to increase an electric field coupling coefficient, and improve electric energy transmission quality by fully utilizing a parasitic capacitance characteristic of the coil neglected in the past research. Wherein, fig. 1 is a three-dimensional diagram of an integrated electromagnetic coupling mechanism, which is mainly composed of four plane square spiral electromagnetic poles and dielectrics, and the front view is as shown in fig. 2, the four electromagnetic poles and the dielectrics are arranged in a stacking way, and the electromagnetic poles P are arranged from bottom to top in sequence 1 (first external magnetic pole), first dielectric, and electromagnetic pole P 2 (first inner electromagnetic pole), electromagnetic pole P 4 (second inner electromagnetic pole), second dielectric, and electromagnetic pole P 3 (second outer electromagnetic pole), electromagnetic pole P 1 And P 3 Has a side length of l 1 Electromagnetic pole P 2 And P 4 Has a side length of l 2 The distance between the electromagnets on the same side, i.e. the thickness of the first and second dielectric, is d s Two inner electromagnetic poles (P) 2 And P 4 ) In betweenDistance is also the electric energy transmission distance d t . The top view of any plane square spiral electromagnetic pole is shown in figure 3, the thickness of the copper foil strip is negligible, and D in the figure out Is the outer diameter of the electromagnetic pole, D in The inner diameter of the electromagnetic pole, w is the width of the copper foil, s is the distance between two adjacent turns of the copper foil, N is the number of turns, and the parameters of the electromagnetic pole satisfy the following relations:
D out ＝D in +2w+(w+s)(2N-1) (1)
for the coupling structure shown in fig. 1, four electromagnetic poles are stacked and cross-coupled with each other, and the mutual inductance and the mutual capacitance formed by the four electromagnetic poles are considered when analyzing the characteristics of the coupling mechanism, so that the structure can be equivalent to a circuit model shown in fig. 4. L in FIG. 4 i For self-induction of electromagnetic poles, M ij Is an electromagnetic pole P i And an electromagnetic pole P j Mutual inductance of (C) ij Is an electromagnetic pole P i And an electromagnetic pole P j Wherein i, j =1,2,3,4.
Example 2
1. System circuit model and equivalent simplification thereof
The embodiment provides an electric energy transmission system of an integrated electromagnetic coupling mechanism. In order to save cost and simplify the circuit, the present embodiment utilizes the capacitance and inductance characteristics of the integrated electromagnetic coupling mechanism, and adopts a compensation-free structure. Meanwhile, in order to further simplify the system structure, a half-bridge inverter circuit is adopted, as shown in fig. 5, in which the first inner electromagnetic pole P of the stacked coupling mechanism is shown 2 Is connected with the high potential end of the inversion output, the first external electromagnetic pole P 1 The unlike terminal of the inverter is connected with the low potential terminal of the inverter output so as to reduce the leakage field radiation.
In order to simplify the analysis, the present embodiment analyzes the system characteristics by using a fundamental wave approximation method. For the circuit model of the coupling mechanism shown in fig. 4, the six-capacitor cross-coupling model can be equivalent to a three-capacitor pi model, so the system circuit model shown in fig. 5 can be equivalent to the circuit shown in fig. 6, where U is the number of the circuits in ＝U dc 2/pi, which is the fundamental component of the input voltage (also the inverted output voltage) of the coupling mechanismMagnitude of the quantity, R eq Is an equivalent load resistance. The parameters in fig. 5 and 6 have the following equivalent transformation relationship:
the electric field coupling coefficient can be expressed as:
furthermore, C can be transformed according to the reciprocity theorem 1 、C 2 And C M The formed pi-type capacitor network is converted into T-type capacitor network, and the inductance element L can be combined with multi-inductance coupling theory 1 -L 4 The decoupling process is performed, and finally the circuit shown in fig. 6 can be simplified into the circuit structure shown in fig. 7, where the parameters in fig. 6 and fig. 7 have the following relationships:
in the present embodiment, the magnetic field coupling coefficient is defined as:
the degree of magnetic coupling between the coils can be explained by this definition.
2. Full resonance and parameter compensation relation of circuit
According to the simplified circuit topology shown in FIG. 7, the circuit is divided into two loops, I 1 And I 2 And the clockwise direction of the current is defined as a positive direction, and the current is written back to a route equation based on Kirchhoff Voltage Law (KVL):
in the formula:
where ω =2 π f is the system operating angular frequency, where f is the system operating frequency. Thus, it can be calculated that:
in the formula I 1 And I 2 Can also be respectively regarded as the system input current I in And an output current I out Therefore, the input impedance of the system can be expressed as:
in practical applications, the stacked coupling mechanism is generally designed as a symmetrical structure, i.e. the electromagnetic pole P 1 And an electromagnetic pole P 3 Uniform size, electromagnetic pole P 2 And an electromagnetic pole P 4 Are of uniform size and P 1 And P 2 Pitch and P of 3 And P 4 Are equal, the circuit parameters in fig. 4 have the following equation relationship:
from equations (2), (4) and (5), it follows that:
by substituting formulae (11) and (12) for formula (10), a can be obtained 22 ＝a 11 +R eq . Due to a in the formula (8) 12 ＝a 21 Thus the input impedance can be reduced to:
in the combination of formulas (8) and (13), if the system is required to operate in the ZPA state, the system input impedance Im (Z) in ) =0, then it must be satisfied that:
or:
(1) if satisfied formula (14)
The combination of equations (10) and (14) yields a system input impedance of:
the system input current and output current can be obtained by combining the equations (9) and (16):
further obtaining the system output voltage as:
(2) if satisfied formula (15)
The input impedance of the system is simplified by combining formulas (10) and (15), and Z can be obtained in ＝R eq The input current and the output of the system can be obtained in the same wayThe current and output voltage are respectively:
3. circuit parameter and electromagnetic coupling mechanism parameter analysis and design
In order to improve the system performance, the finite element simulation software Maxwell is adopted to perform simulation analysis on the characteristics of the electromagnetic coupling mechanisms with different sizes, and the coupling mechanisms are optimally designed. According to the prior art, the self-inductance calculation formula of the square plane spiral coil is as follows:
wherein, mu 0 Is vacuum permeability, N is the number of turns of the coil, D avg Is the average value of the inner and outer diameters of the coil, i.e. D avg ＝(D out +D in ) P is the compression ratio of the coil, i.e. p = (D) out -D in )/(D out +D in )，c 1 -c 4 The value of (c) depends on the layout shape of the coil, and when the coil is square, c 1 ＝1.27，c 2 ＝2.07，c 3 ＝0.18，c 4 =0.13. In addition, according to a theoretical formula of capacitance, the coupling capacitance between the two electromagnetic poles is in direct proportion to the copper laying area of the square planar spiral coil and in inverse proportion to the electromagnetic pole spacing.
In practical applications, the outer diameter of the electromagnetic pole is generally determined according to specific requirements, and is, in this embodiment, 500mm by 500mm (D) out Outer electromagnetic pole (P) =500 mm) size 1 And P 3 ) As a sampleAnd (5) carrying out research. When the outer diameter D is shown by the combination of formulas (1) and (22) out At a certain time, the self-inductance of the outer electromagnetic pole is mainly equal to the width w of the copper foil of the outer electromagnetic pole out The number of turns of copper foil N out And the pitch s of turns out In addition to the above parameters, the mutual inductance and coupling capacitance between the inner and outer electromagnetic poles is related to the copper foil width w of the inner electromagnetic pole in The number of turns of copper foil N in Turn-to-turn spacing s in Distance d between the same side electromagnetic pole s And a transmission distance d t And (6) correlating.
If organic glass is used as a medium (the relative dielectric constant is 3.4) between the electromagnetic poles on the same side, parameters of the coupling mechanism shown in the table 1 are used as invariants, and self-inductance, mutual inductance and coupling capacitance among the four electromagnetic poles can be obtained through Maxwell simulation according to the number N of turns of copper foil of the electromagnetic pole on the inner side in Thereby obtaining the magnetic field coupling coefficient k of the coupling mechanism IPT And coefficient of electric field coupling k CPT With N in The variation of (c) is shown in fig. 8. In the figure k IPT Both negative numbers are relevant for the determination of the homonymous end of the coupling coil, which is influenced by the direction of the current in the coil, i.e. relevant for the wiring mode of the coil.
TABLE 1 coupling mechanism parameters (N) in Is a variable quantity)
| Parameter(s) | Value taking | Parameter(s) | Value taking |
| N out | 15 | d s | 10mm |
| d t | 60mm | w out | 10mm |
| s out | 5mm | w in | 10mm |
| s in | 5mm |
From the above analysis, the system operating frequency f with N in equation (14) can be obtained in And C in the formula (16) a 、L 1m And L 2m With N in The variation relationship of (a). The combination of (14) and (16) yields the input impedance Z for the first ZPA in With N in And an equivalent load resistance R eq The variation of (c) is as shown in fig. 9. As can be seen from FIG. 9, when R is eq When the resistance value is low (10-100 omega), the input impedance is in a high-impedance state, and the influence of the change of the number of turns of the inner electromagnetic pole copper foil on the input impedance is not large, so that the pick-up power of the load is greatly reduced. When R is eq Is high in resistance value (10) 3 -10 4 Ω) the value of the input impedance varies between about 10 Ω and 100 Ω, with a small pick-up current of the load.
Except for analyzing N in To Z in In addition to the influence of (c), the parameter pair Z in Table 1 can be analyzed similarly in The influence of (c). But at electromagnet pole sizes of 500mm,the number of coil turns is the main parameter affecting self-inductance and mutual inductance under the application limit of 60mm transmission distance, so s out 、s in 、w out And w in To Z in Has little influence on Z in The decisive role of which is R eq 。
As can be seen from the above analysis, this operation mode is only suitable for the equivalent load resistance R eq For larger applications. In most practical applications, R eq Typically between 10-100 omega, this embodiment will focus on the analysis and optimized design of the coupling mechanism in the case of the second ZPA.
For the second ZPA operating condition, the system input impedance Z in ＝R eq The voltage and current which can be picked up by the load are relatively large, and the load is suitable for most application occasions. From equation (15), the system resonant frequency can be calculated as:
in the formula:
it can be seen that for the WPT system without the additional compensation structure proposed in this embodiment, there are two system resonance frequencies. The parameters of the coupling mechanism shown in Table 1 are also used as invariant to obtain the number N of turns of the copper foil of the electromagnetic pole with the two frequencies along the inner side in And an equivalent load resistance R eq As shown in fig. 10. It can be seen from fig. 10 that the system resonance frequencies are mainly N and N in Related to, by R eq Has a smaller influence.
In order to determine the operating frequency of the system, the present embodiment analyzes the voltage to ground of each electromagnetic pole at the two resonant frequencies. Due to the electromagnetic pole P 1 Is connected to the negative pole of DC input, P 2 Connected to the high potential side of the inverter output, thus P 1 Voltage U on P1 Is zero, P 2 Voltage U on P2 Is U in . By U in ＝100V，R eq When N is equal to 40 Ω, as shown in fig. 10, the analysis was performed as an example in When different values are taken, the resonant frequency of the system is different, and the voltages to ground of the four electromagnetic poles are greatly different under different resonant frequencies. When the system operating frequencies f are respectively equal to f 1 And f 2 Then, the electromagnetic pole P can be obtained 3 And P 4 Amplitude of voltage to ground U P3 And U P4 With N in Fig. 11 shows the variation curve of (a). As is evident from fig. 11, in f 2 U obtained as system operating frequency P3 And U P4 Is much higher than f 1 As U at system operating frequency P3 And U P4 Therefore, f is selected 1 As the system working frequency, the leakage field of the coupling mechanism will be effectively reduced, and the safety performance of the system will be improved, which will be mainly aimed at f = f hereinafter 1 Is analyzed and designed.
4. System parameter determination and simulation verification
A system simulation model is built under an MATLAB/Simulink platform based on the circuit shown in FIG. 5, the electric field coupling coefficient, the magnetic field coupling coefficient and the system working frequency of the system are comprehensively considered according to the analysis on the circuit parameters and the coupling mechanism parameters, the geometric parameters of the selected electromagnetic coupling mechanism are shown in a table 2, and the parameters shown in a table 3 are obtained according to the design on the circuit parameter relation in the table 2 for simulation verification.
TABLE 2 coupling mechanism geometry parameters
| Parameter(s) | Value taking | Parameter(s) | Value taking |
| N out | 15 | N in | 9 |
| s out | 5mm | w out | 10mm |
| s in | 5mm | w in | 10mm |
| d s | 10mm | d t | 60mm |
TABLE 3 Circuit simulation parameters
| Parameter(s) | Value taking | Parameter(s) | Value taking |
| f | 1.056MHz | L 1 | 64.622μH |
| U dc (U in ) | 157.08V(100V) | L 2 | 19.517μH |
| R L (R eq ) | 49.348Ω(40Ω) | L 3 | 64.407μH |
| C 12 | 324.98pF | L 4 | 19.432μH |
| C 13 | 30.376pF | M 12 | 22.731μH |
| C 14 | 3.0998pF | M 13 | 28.369μH |
| C 23 | 3.1395pF | M 14 | 12.367μH |
| C 24 | 13.198pF | M 23 | 12.366μH |
| C 34 | 324.14pF | M 24 | 7.2848μH |
| M 34 | 22.722μH |
By performing impedance analysis on the simulation model, a relation graph of impedance and system operating frequency as shown in fig. 12 is obtained, and as can be seen from the above analysis, f is generally selected 1 And f 2 The working frequency of the system is more suitable for practical application, but is compared with the working frequency f 2 At frequency operation, the system is at f 1 The voltage of the electromagnetic pole under the working frequency is greatly reduced, so f is selected 1 And as the system working frequency, the working frequency obtained by simulation is consistent with a theoretical calculated value.
Fig. 13 shows the inverted output voltage and current waveforms of the system, and it can be seen that the voltage and the current are in phase, the system realizes ZPA operation, and the amplitude of the input current of the system is 2.484A through measurement. Due to U in ＝U dc ·2/π，R eq ＝R L ·8/π 2 From equation (19), I can be calculated in ＝U in /R eq =2.5A, simulation and theoretical derivation are substantially identical.
Fig. 14 shows waveforms of system output voltage and current, and it can be calculated that the system output power is about 134W, and the output power is substantially consistent with the input power because the internal resistance loss of the electromagnetic pole is not considered in the simulation.
FIGS. 15 and 16 show the voltage to ground and the current through the four poles, pole P, respectively 1 Is directly connected with the negative electrode of a direct current power supply, so that the ground voltage is zero and an electromagnetic pole P 2 The voltage to ground is the inversion output voltage; in addition, as can be seen from the structure shown in FIG. 5, the electromagnetic pole P 1 And P 2 Through electromagnetic pole P 3 And P 4 The currents of (a) are also equal.
Finite element simulation was performed on the electromagnetic field distribution of the coupling mechanism under the Ansys Maxwell simulation platform using the above-mentioned voltage and current as excitation sources, and the electric field intensity distribution and the magnetic field intensity distribution as shown in fig. 17 and 18 were obtained. According to the IEEE safety standard, when the operating frequency is 1.056MHz, the safe electric field intensity of the human body is 614V/m, and the safe magnetic field intensity is 15.4356A/m, thereby the safe distance of 60mm shown in FIGS. 17 and 18 can be obtained.
5. Conclusion
In order to simplify the WPT system structure, save cost, and improve system power density, the present embodiment constructs an uncompensated WPT system based on the novel integrated electromagnetic coupling mechanism provided in embodiment 1, and performs system analysis and design. The equivalent model of the coupling mechanism is simplified based on a circuit theory and a mutual inductance coupling theory, and a parameter design method meeting the circuit full resonance is provided for an uncompensated WPT system. By analyzing the influence of the geometric parameters of the coupling mechanism on the system performance, a proper electromagnetic coupling mechanism is designed, the transmission distance of the system can reach 60mm without any additional compensation device, the transmission power is over 130W, and the external electromagnetic field radiation of the coupling mechanism is effectively reduced. Finally, the theory and the method of the embodiment are verified through simulation, and the simulation result is basically consistent with the theoretical calculation.
Example 3
Based on embodiment 2, the present embodiment provides an integrated power supplyThe electric energy transmitting terminal of the magnetic coupling mechanism can be installed in an electric energy transmitting device and is provided with a half-bridge inverter circuit and a transmitting terminal electromagnetic pole, wherein the half-bridge inverter circuit adopts the half-bridge inverter circuit in the system in embodiment 2, and the transmitting terminal electromagnetic pole adopts the first external electromagnetic pole P in embodiment 2 1 A first inner electromagnetic pole P 2 With respect to the first external electromagnetic pole P 1 A first inner electromagnetic pole P 2 More specific parameter design can be consistent with embodiment 2, and can also be set according to specific application requirements.
It should be noted that the power transmitting device, equipment and the like including the power transmitting terminal are also included in the scope of the present invention.
Example 4
Based on embodiment 2, this embodiment provides an electric energy receiving terminal of an integrated electromagnetic coupling mechanism, which can be installed in a mobile terminal, and is provided with a receiving terminal electromagnetic pole and a rectifying and filtering circuit, wherein the second outer electromagnetic pole P in the receiving terminal electromagnetic pole embodiment 2 3 A second inner electromagnetic pole P 4 And a rectifying and smoothing circuit in accordance with embodiment 2, wherein an RC smoothing circuit is used, and a low potential terminal thereof is connected to the second external electromagnetic pole P 3 A high potential end is connected with the second inner electromagnetic pole P 4 The synonym end of (c). And with respect to the second outer electromagnetic pole P 3 A second inner electromagnetic pole P 4 More specific parameter design can be consistent with embodiment 2, and can also be set according to specific application requirements.
It should be noted that a mobile terminal, other devices, apparatuses, etc. including the power receiving end are also included in the scope of the present invention.
In summary, the present invention provides a novel integrated electromagnetic coupling mechanism, a Wireless Power Transfer (WPT) system based on the coupling mechanism, and an electric energy transmitting terminal and an electric energy receiving terminal based on the coupling mechanism and capable of being applied independently. The coupling mechanism is formed by stacking four square plane spiral copper foil coils, integrates electric field coupling and magnetic field coupling, integrates inductance and capacitance, has self-compensation characteristic, can realize high-efficiency wireless electric energy transmission without an additional compensation structure, can effectively reduce the volume and cost of a system, and improves the power density of the system. Aiming at the system, the invention firstly constructs and simplifies a coupling mechanism circuit model based on a circuit theory and a mutual inductance coupling theory, analyzes and designs the electric parameters of the coupling mechanism by utilizing the self-compensation characteristic of the coupling mechanism, and provides the basic conditions of the full-resonance work of the system. And then, constructing an integrated electromagnetic coupling mechanism simulation model based on a Maxwell finite element simulation platform, analyzing the influence of the relation between the electrical parameters and the geometric parameters of the coupling mechanism on the system performance, providing the variation rule of the electromagnetic field coupling coefficient and the system resonance frequency, and optimally designing the electromagnetic pole structure. Finally, the superiority of the coupling mechanism and the uncompensated WPT system design method provided by the invention is verified through simulation, and the feasibility and the effectiveness of the theory and the method are clarified.
While the preferred embodiments of the present invention have been illustrated and described, it will be understood that the invention is not limited to the details of construction, and that various changes, modifications, substitutions, combinations and simplifications may be made without departing from the spirit and scope of the invention.
Claims (8)
1. Electric energy transmission system of integrated electromagnetic coupling mechanism, the integrated electromagnetic coupling mechanism comprises a first external electromagnetic pole P arranged in a stacked mode 1 A first dielectric, a first inner electromagnetic pole P 2 And a second inner electromagnetic pole P arranged in a stacked manner 4 A second dielectric, a second outer electromagnetic pole P 3 The method is characterized in that: the electric energy transmission system comprises an electric energy transmitting end and an electric energy receiving end; the electric energy transmitting terminal is provided with a half-bridge inverter circuit and a transmitting terminal electromagnetic pole, and the transmitting terminal electromagnetic pole comprises the first outer electromagnetic pole P 1 The first inner electromagnetic pole P 2 The low potential end of the half-bridge inverter circuit is connected with the first external electromagnetic pole P 1 The high potential end of the half-bridge inverter circuit is connected with the first inner electromagnetic pole P 2 The same name end of (1); the electric energy receiving end is provided with a receiving end electromagnetic pole and a rectifierA filter circuit, wherein the receiving end electromagnetic pole comprises the second outer electromagnetic pole P 3 The second inner electromagnetic pole P 4 The low potential end of the rectifying and filtering circuit is connected with the second outer electromagnetic pole P 3 The high potential end of the rectifying and filtering circuit is connected with the second inner electromagnetic pole P 4 The synonym end of (c).
2. The power delivery system of an integrated electromagnetic coupling mechanism of claim 1, wherein the first outer electromagnetic pole P 1 The first inner electromagnetic pole P 2 The second inner electromagnetic pole P 4 The second outer electromagnetic pole P 3 The design of (2) satisfies:
when the temperature is higher than the set temperature
Wherein, ω =2 π f is the system operating angular frequency, f is the system operating frequency, C A ＝C 1 +2C M ，
M ij Is an electromagnetic pole P i And an electromagnetic pole P j Mutual inductance between them, C ij Is an electromagnetic pole P i And an electromagnetic pole P j Formed coupling capacitance, L i Is an electromagnetic pole P i I, j =1,2,3,4.
3. The power delivery system of an integrated electromagnetic coupling mechanism of claim 2, wherein the first outer electromagnetic pole P 1 The first inner electromagnetic pole P 2 The second inner electromagnetic pole P 4 And said second outer electromagnetic pole P 3 Is designed or satisfied:
when in use
When the temperature of the water is higher than the set temperature,
R eq is an equivalent load resistance.
4. An electric power transmission system of an integrated electromagnetic coupling mechanism according to claim 2 or 3, wherein:
wherein, the first and the second end of the pipe are connected with each other,
5. the integrated electromagnetic coupling mechanism power delivery system of claim 1, wherein: the first inner electromagnetic pole P 2 And the second inner electromagnetic pole P 4 Are opposite and spaced by a distance d t The first external electromagnetic pole P 1 The first inner electromagnetic pole P 2 The second inner electromagnetic pole P 4 And the second outer electromagnetic pole P 3 Are formed by spirally winding square metal lines with consistent specifications in the same direction.
6. The power delivery system of an integrated electromagnetic coupling mechanism of claim 5, wherein: the first external electromagnetic pole P 1 And said second outer electromagnetic pole P 3 Of uniform size, said first inner electromagnetic pole P 2 And said second inner electromagnetic pole P 4 The dimensions are uniform and the thickness of the first dielectric and the thickness of the second dielectric are equal.
7. The power delivery system of an integrated electromagnetic coupling mechanism of claim 5, wherein: the first external electromagnetic pole P 1 The first inner electromagnetic pole P 2 The second inner electromagnetic pole P 4 And the second external electromagnetPolar P 3 Are wound into a plane spiral square electromagnetic pole.
8. The integrated electromagnetic coupling mechanism power delivery system of claim 5, wherein: any electromagnetic pole is a plane square spiral electromagnetic pole, and the parameters of the electromagnetic pole meet the following requirements:
D out ＝D in +2w+(w+s)(2N-1)
wherein D is out 、D in The outer diameter and the inner diameter are respectively, w is the width of the square metal line, s is the distance between two adjacent turns of the square metal line, and N is the number of turns.
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