阅读说明：本技术 基于正交dd型线圈的无线供电耦合机构及其参数设计方法 (Wireless power supply coupling mechanism based on orthogonal DD (direct digital) coil and parameter design method thereof ) 是由 谢诗云 杨奕 张路 周青山 李恋 熊山香 于 2021-08-12 设计创作，主要内容包括：本发明涉及无线充电技术领域,具体公开了一种基于正交DD型线圈的无线供电耦合机构及其参数设计方法,耦合机构由双层正交排列的两对DD型线圈组成,两对DD型线圈的解耦易于实现而且所激发磁场呈周期性旋转分布,兼具抗偏移和抗偏转性能。参数设计方法通过分析线圈自感、互感及耦合系数的作用规律,给出了双层DD型线圈的空间位置和铁氧体导磁机构的特征参数,可使得接收端在水平偏移、垂向偏移和垂向偏转三种情况下,发射端与接收端保持较高的耦合系数,实现抗偏移和抗偏转性能最佳。实验表明,在水平横向和纵向偏移±150mm,垂向偏转0～90°范围内,传输距离为130mm时,基于该无线供电耦合机构的传输系统,其输出功率均不低于500W,传输效率不低于82.5％。(The invention relates to the technical field of wireless charging, and particularly discloses a wireless power supply coupling mechanism based on orthogonal DD (direct-current) coils and a parameter design method thereof. The parameter design method gives the space position of the double-layer DD-type coil and the characteristic parameters of the ferrite magnetic conducting mechanism by analyzing the action rules of the self inductance, the mutual inductance and the coupling coefficient of the coil, so that the transmitting end and the receiving end can keep higher coupling coefficient under the three conditions of horizontal deviation, vertical deviation and vertical deviation of the receiving end, and the optimal anti-deviation and anti-deflection performances are realized. Experiments show that when the horizontal transverse and longitudinal deviation is +/-150 mm, the vertical deflection is within the range of 0-90 degrees, and the transmission distance is 130mm, the output power of the transmission system based on the wireless power supply coupling mechanism is not lower than 500W, and the transmission efficiency is not lower than 82.5%.)

1. Wireless power supply coupling mechanism based on quadrature DD type coil includes transmitting terminal and receiving terminal, its characterized in that:

the receiving end comprises a first DD type receiving coil, a second ferrite core and a second shielding plate which are arranged in a hierarchical manner;

the first DD-type transmitting coil and the second DD-type transmitting coil are orthogonally superposed, the second DD-type receiving coil and the second DD-type receiving coil are orthogonally superposed, and the first DD-type transmitting coil and the first DD-type receiving coil are oppositely arranged in the same direction;

the first DD-type transmitting coil, the second DD-type transmitting coil, the first DD-type receiving coil and the second DD-type receiving coil are identical DD-type coils, each DD-type coil is formed by connecting a first D-type coil and a second D-type coil in series, the first D-type coil and the second D-type coil are identical in size and number of turns, opposite in winding direction and separated by a distance D₁，0＜d₁≤300mm。

2. A quadrature DD coil based wireless power coupling mechanism as claimed in claim 1, wherein: and two paths of excitation currents which are introduced into the first DD type transmitting coil and the second DD type transmitting coil have equal amplitudes and 90-degree phase difference, and at the moment, a rotating magnetic field is formed in the orthogonal overlapping area of the first DD type transmitting coil and the second DD type transmitting coil.

3. A quadrature DD coil based wireless power coupling mechanism as claimed in claim 2, wherein: the first shielding plate and the second shielding plate adopt the same square ferrite plate, and the center of the square ferrite plate is superposed with the orthogonal center of the two orthogonal DD-type coils.

4. A quadrature DD coil based wireless power coupling mechanism as claimed in claim 3, wherein: the side length of the square ferrite plate is 60-400 mm, and the thickness of the square ferrite plate is 3-30 mm.

5. A quadrature DD coil-based wirelessly powered coupling mechanism as claimed in claim 4, wherein: the first DD type transmitting coil is connected to a first wireless energy transmitting channel formed by a first full-bridge inverter and a first LCC transmitting compensation circuit; the second DD type transmitting coil is connected to a second wireless energy transmitting channel formed by a second full-bridge inverter and a second LCC transmitting compensation circuit; the first DD type receiving coil is connected to a first wireless energy receiving channel formed by the first capacitor resonance network and the first full-bridge rectifying circuit; and the second DD type receiving coil is connected to a second wireless energy receiving channel formed by the second capacitor resonance network and the second full-bridge rectifying circuit.

6. A method for designing parameters of a wireless power supply coupling mechanism, which is used for the wireless power supply coupling mechanism based on the orthogonal DD type coil as claimed in claim 5, comprising the steps of:

s1, setting all D-type coils to keep the same size and the same number of turns;

s2, setting the thickness h of the square ferrite plate₂At an initial value, set d₁Gradually increased, and the side length W of the square ferrite plate₂Following d₁Synchronously with the increase of the voltage, recording the self-inductance of the DD-type coil, the mutual inductance between the DD-type coils and the change of the system equivalent coupling coefficient, and recording the self-inductance, the mutual inductance between the DD-type coils and the change of the system equivalent coupling coefficient according to the recorded changeDetermination of the Change d₁The optimum value of (d);

s3, setting h₂At the initial value, d₁Taking its optimal value, setting W₂Gradually increasing, recording the variation of the equivalent coupling coefficient of the system, and determining W according to the variation₂The optimum value of (d);

s4, setting d₁Take its optimum value, W₂Taking the optimal value, setting h₂Gradually increasing, recording the change condition of the equivalent coupling coefficient of the system, and determining h according to the change condition₂The optimum value of (d);

s5, setting parameters of the wireless power supply coupling mechanism as follows: d₁Take its optimum value, W₂Taking the optimal value h₂And taking the optimal value.

7. The method of claim 6, wherein the method comprises: in the step S2, it is determined that d is the maximum equivalent coupling coefficient of the system₁Is taken as its optimum value.

8. The method of claim 6, wherein the method comprises: in the step S3, the time W when the equivalent coupling coefficient of the system is maximum is determined₂Is taken as its optimum value.

9. The method of claim 6, wherein the method comprises: in step S4, the change condition of the system equivalent coupling coefficient and the realistic limitation factor are combined to determine the time h when the system equivalent coupling coefficient is larger₂Is taken as its optimum value.

Technical Field

The invention relates to the technical field of wireless charging, in particular to a wireless power supply coupling mechanism based on an orthogonal DD (direct digital) coil and oriented to an electric vehicle wireless charging application occasion and a parameter design method thereof.

Background

The electric vehicle based on the Wireless Power Transfer (WPT) mode has the advantages of safety, convenience, strong environmental adaptability and the like in the charging process, so that the electric vehicle is widely concerned by domestic and foreign scholars. The key problem to be solved urgently by the WPT system of the electric automobile is to reduce the requirement on the alignment precision of the automobile and the energy emission mechanism in the parking process and improve the stability of the picking power of the automobile-mounted mechanism. Aiming at the tolerable offset deflection degree and the transmission energy efficiency performance of a WPT system, the technical standards at home and abroad such as GB/T38775, SAEJ2954, IEC61980 and the like set that the transverse offset (door-to-door direction, namely Y axis) is not less than 100mm, the longitudinal offset (driving direction, namely X axis) is not less than 75mm, the vertical deflection (namely Z axis deflection) is not less than 10 degrees, and reference ranges of performance parameters such as system operation frequency, efficiency, power level, clear distance between a transmitting end and a vehicle-mounted receiving end and the like are given. On the basis of the offset deflection range set by the existing standard, in order to further improve the offset deflection resistance of the electric vehicle WPT system, the existing literature mainly adopts three modes: an energy coupling channel is additionally arranged, the distribution of a coupling magnetic field is optimized, and a composite resonant circuit is adopted.

The additional arrangement of an energy coupling channel (such as a single-transmission-multiple-reception coupling mode) can effectively improve the anti-offset and anti-deflection characteristics of the WPT system of the electric automobile, but cannot simultaneously overcome the following limitations: firstly, the anti-deviation and anti-deflection performance of the coupling mechanism cannot be considered; secondly, decoupling between coils at the same end is difficult to realize; and thirdly, an excitation current control strategy adopted by the transmitting coil is too complex.

The existing schemes for optimizing the spatial distribution of the coupling magnetic field can improve the anti-offset deflection capability of the coupling mechanism, but the related documents either cannot combine the anti-offset and anti-deflection performances, or unbalanced coupling between multiple coils at the transmitting end causes an excitation current control strategy to be too complex.

The use of composite resonant circuits can improve the deflection resistance of the coupling mechanism to some extent, however, this approach generally does not achieve high deflection resistance, and the resonant element must also withstand high operating voltages or currents in the case of large deflections.

It can be seen that the existing electric vehicle WPT system cannot have the characteristics of offset resistance and deflection resistance and is difficult to realize the same-end coil decoupling.

Disclosure of Invention

The invention provides a wireless power supply coupling mechanism based on an orthogonal DD (direct digital) coil and a parameter design method thereof, and solves the technical problems that: how to enable the electric automobile WPT system to have the anti-deviation and anti-deflection characteristics and achieve the same-end coil decoupling.

In order to solve the technical problem, the invention provides a wireless power supply coupling mechanism based on an orthogonal DD type coil, which comprises a transmitting end and a receiving end, wherein the transmitting end comprises a first DD type transmitting coil, a second DD type transmitting coil, a first ferrite core and a first shielding plate which are arranged in a hierarchical manner, and the receiving end comprises a first DD type receiving coil, a second ferrite core and a second shielding plate which are arranged in a hierarchical manner;

the first DD-type transmitting coil and the second DD-type transmitting coil are orthogonally superposed, the second DD-type receiving coil and the second DD-type receiving coil are orthogonally superposed, and the first DD-type transmitting coil and the first DD-type receiving coil are oppositely arranged in the same direction;

the first DD-type transmitting coil, the second DD-type transmitting coil, the first DD-type receiving coil and the second DD-type receiving coil are identical DD-type coils, each DD-type coil is formed by connecting a first D-type coil and a second D-type coil in series, the first D-type coil and the second D-type coil are identical in size and number of turns, opposite in winding direction and separated by a distance D₁，0＜d₁≤300mm。

Preferably, the two excitation currents introduced into the first DD type transmitting coil and the second DD type transmitting coil have equal amplitudes and 90 ° phase difference, and at this time, a rotating magnetic field is formed in the orthogonal overlapping region of the first DD type transmitting coil and the second DD type transmitting coil.

Preferably, the first shielding plate and the second shielding plate are made of the same square ferrite plate, and the center of the square ferrite plate coincides with the orthogonal center of the two orthogonal DD type coils.

Preferably, the side length of the square ferrite plate is 60-400 mm, and the thickness of the square ferrite plate is 3-30 mm.

Preferably, the first DD type transmitting coil is connected to a first wireless energy transmitting channel formed by the first full-bridge inverter and the first LCC transmitting compensation circuit; the second DD type transmitting coil is connected to a second wireless energy transmitting channel formed by a second full-bridge inverter and a second LCC transmitting compensation circuit; the first DD type receiving coil is connected to a first wireless energy receiving channel formed by the first capacitor resonance network and the first full-bridge rectifying circuit; and the second DD type receiving coil is connected to a second wireless energy receiving channel formed by a second capacitance resonance network and a second full-bridge rectifying circuit.

The wireless power supply coupling mechanism based on the orthogonal DD type coils is composed of two pairs of DD type coils which are arranged in a double-layer orthogonal mode, decoupling of the two pairs of DD type coils is easy to achieve, an excited magnetic field is distributed in a periodic rotating mode, and the wireless power supply coupling mechanism has anti-deviation and anti-deflection performances.

Aiming at the wireless power supply coupling structure, the invention also provides a parameter design method of the wireless power supply coupling mechanism, which is used for the wireless power supply coupling structure of the orthogonal DD type coil and comprises the following steps:

s1, setting all D-type coils to keep the same size and the same number of turns;

s2, setting the thickness h of the square ferrite plate₂At an initial value, set d₁Gradually increased and the side length W of the square ferrite plate₂Following d₁Synchronously, recording the self-inductance of the DD-type coil, the mutual inductance between the DD-type coils and the variation of the system equivalent coupling coefficient, and determining d according to the variation₁The optimum value of (d);

s3, setting h₂At an initial value, d₁Taking its optimal value, setting W₂Gradually increasing, recording the variation of the equivalent coupling coefficient of the system, and determining W according to the variation₂The optimum value of (d);

s4, setting d₁Take its optimum value, W₂Taking the optimal value, setting h₂Gradually increasing, recording the change condition of the equivalent coupling coefficient of the system, and determining h according to the change condition₂The optimum value of (d);

s5, setting parameters of the wireless power supply coupling mechanism as follows: d₁Take its optimum value, W₂Taking the optimal value h₂And taking the optimal value.

Further, in the step S2, it is determined that d is the maximum equivalent coupling coefficient of the system₁Is taken as its optimum value.

Further, in the step S3, it is determined that W is the maximum equivalent coupling coefficient of the system₂Is taken as its optimum value.

Further, in the step S4, the variation of the system equivalent coupling coefficient and the realistic restriction factor are combined to determine the time h when the system equivalent coupling coefficient is larger₂Is taken as its optimum value.

According to the parameter design method of the wireless power supply coupling mechanism, the space position of the double-layer DD-type coil and the characteristic parameters of the ferrite magnetic conduction mechanism are given by analyzing the action rules of the self-inductance, the mutual inductance and the coupling coefficient of the coil, so that the transmitting end and the receiving end can keep higher coupling coefficients under the three conditions of horizontal deviation, vertical deviation and vertical deviation of the receiving end, and the optimal anti-deviation and anti-deflection performances are realized. Experiments show that when the horizontal and longitudinal deviation is +/-150 mm, the vertical deflection is within 0-90 degrees, and the transmission distance is 130mm, the output power of the transmission system based on the wireless power supply coupling mechanism is not lower than 500W, and the transmission efficiency is not lower than 82.5%.

Drawings

Fig. 1 is an exploded view of a wireless power coupling mechanism based on a quadrature DD coil according to an embodiment of the present invention;

FIG. 2 is a front view of FIG. 1 provided by an embodiment of the present invention;

fig. 3 is a DQDD coil winding method and a magnetic field distribution diagram according to an embodiment of the present invention;

fig. 4 is a circuit diagram of a WPT system based on a DQDD magnetic coupling mechanism provided by an embodiment of the present invention;

FIG. 5 is a circuit diagram of the open-circuit voltage and the short-circuit current at the pickup end of the single energy channel WPT according to the embodiment of the present invention;

FIG. 6 is a circuit diagram of the open-circuit voltage and the short-circuit current at the pickup end of the multi-channel WPT according to the embodiment of the present invention;

fig. 7 is a diagram of simulation results of self-inductance, mutual inductance, and equivalent coupling coefficients of the DQDD magnetic coupling mechanism and distance variations between D-type coils on the same layer according to an embodiment of the present invention;

FIG. 8 is a diagram of simulation results of ferrite side length and equivalent coupling coefficient provided by an embodiment of the present invention;

FIG. 9 is a graph of simulation results of ferrite thickness and equivalent coupling coefficient provided by an embodiment of the present invention;

FIG. 10-1 is a block diagram (including dimensional parameters) of a CP coil and a DD coil provided by an embodiment of the present invention;

fig. 10-2 is a diagram of coupling coefficient retention coefficients of the CP coil, the DD coil, the pre-optimized DQDD coil, and the post-optimized DQDD coil in the XOY horizontal plane, according to an embodiment of the present invention;

FIG. 11 is a diagram of equivalent coupling coefficient retention coefficients of a CP coil, a DD coil, a pre-optimized DQDD coil, and a post-optimized DQDD coil shifted along the Z-axis according to an embodiment of the present invention;

FIG. 12 is a diagram of equivalent coupling coefficient retention coefficients of deflection along the Z axis for the CP coil, the DD coil, the pre-optimized DQDD coil and the post-optimized DQDD coil provided by the embodiment of the present invention;

FIG. 13 shows M when the receiving end shifts in the XOY horizontal plane according to the embodiment of the present invention_t1r1、M_t1r2、M_t2r1And M_t2r2A change situation graph;

FIG. 14 shows M when the receiver is shifted along the Z-axis according to an embodiment of the present invention_t1r1、M_t1r2、M_t2r1And M_t2r2A change situation graph;

FIG. 15 illustrates M during Z-axis deflection of a receiver according to embodiments of the present invention_t1r1、M_t1r2、M_t2r1And M_t2r2A change situation graph;

figure 16 is an equivalent circuit diagram of a WPT system in the absence of cross-coupling provided by an embodiment of the present invention;

figure 17 is an equivalent circuit diagram of a WPT system in the presence of cross-coupling provided by an embodiment of the present invention;

FIG. 18 is a graph of experimental waveforms for positive receive alignment, X offset 100mm, and Y offset 100mm provided by an embodiment of the present invention;

FIG. 19 is a waveform diagram of primary and secondary current and voltage detection experiments with X offset 100mm and Y offset 100mm, and 15 ° deflection along Z axis, according to an embodiment of the present invention;

fig. 20 is a graph of equivalent coupling coefficients of a receiving end in an XOY horizontal plane offset according to an experiment provided in the embodiment of the present invention;

FIG. 21 is a diagram of equivalent coupling coefficients of a receiving end measured by simulation according to an embodiment of the present invention when the receiving end deviates in an XOY horizontal plane;

FIG. 22 is a diagram of equivalent coupling coefficients of an experimental and simulated receiver shifted along the Z-axis according to an embodiment of the present invention;

fig. 23 is a diagram of equivalent coupling coefficients of an experimental and simulated receiver deflecting along the Z-axis according to an embodiment 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.

In order to enable an electric vehicle WPT system to have anti-offset and anti-deflection characteristics and achieve on-end coil decoupling, an embodiment of the invention firstly provides a wireless power supply coupling mechanism based on orthogonal DD-type coils, as shown in an exploded view of fig. 1 and a front view of fig. 2, the coupling mechanism comprises a transmitting deviceA transmitting end including a first DD-type transmitting coil L arranged in a layer_t1A second DD type transmitting coil L_t2(Length W)₃) A first ferrite core, a first shielding plate (square aluminum plate, side length marked as W)₁) The receiving end comprises a second shielding plate (the same aluminum plate as the first shielding plate), a second ferrite core and a second DD-type receiving coil L which are arranged in a hierarchical manner_r2And a first DD type reception coil L_r1Wherein the second DD type transmitting coil L_t2And a first DD type transmitting coil L_t1Orthogonally superposed, second DD-type receiving coil L_r2And a first DD type receiving coil L_r1Orthogonally superposed and first DD-type transmitting coil L_t1And a first DD type receiving coil L_r1The same direction is opposite, and when there is no offset and no deflection, the first DD type transmitting coil L_t1And a first DD type receiving coil L_r1Is opposite to the same direction. The same direction is understood here to mean that the first DD type transmitting coil L is shown in fig. 1 and 2_t1Respectively correspond to the first DD type receiving coil L_r1Is parallel to the other when there is no deflection. The orthogonal superposition relationship of the two DD-type coils at the transmitting end is shown in fig. 3, and due to the Double-layer orthogonal DD relationship, 2 DD-type coils which are overlapped in a positive manner are combined to be called DQDD (Double-layer orthogonal Double-D) coils, and the coupling mechanism adopting the two DQDD coils in the embodiment is called a DQDD magnetic coupling mechanism.

As shown in FIGS. 1 and 2, the first shielding plate and the second shielding plate are identical square ferrite plates with the edge length marked as W₂The center of the square ferrite plate is superposed with the orthogonal centers of the two orthogonal DD coils, and the established space coordinate system takes the orthogonal center of the transmitting end DQDD coil as the origin of coordinates, the automobile driving direction as an X axis and the door-to-door direction as a Y axis.

As shown in fig. 1 and 2, a second DD type transmitting coil L_t2A first DD type transmitting coil L_t1And a second DD type receiving coil L_r2A first DD type receiving coil L_r1The same DD type coil was used. As shown in figures 1,2 and 3, the DD type coil is formed by connecting a first D type coil and a second D type coil in seriesThe first D-type coil and the second D-type coil have the same size and the same number of turns, opposite winding directions and a distance D₁，0＜d₁300mm or less, in FIG. 2 the width of the D-shaped coil is marked W₄. Here, as shown in fig. 3, for the DD-type coil placed transversely, the D-type coil on the left side is wound clockwise, and then the D-type coil on the right side is wound counterclockwise, and the winding manner of the other DD-type coils is the same, and only the installation positions are different. Based on the space position and the winding method of the DQDD coil as shown in FIG. 3, no coupling exists between the two layers of DD coils, and the synthetic magnetomotive force of the DQDD coil rotates periodically under the set excitation condition, and a same-frequency rotating magnetic field is generated in the corresponding space. The reason why the two orthogonal layers of DD coils are not coupled is that the positions of the two orthogonal layers of DD coils satisfy the orthogonal relation and the reverse winding method of the DD coils, on one hand, the mutual coupling net magnetic flux between the DD coils of the adjacent layers is close to zero, and on the other hand, the mutual coupling magnetic flux cancels out the induced voltage generated by the DD coils.

The resultant rotating magnetomotive force generated by the transmitting-end DQDD coil depends on the excitation current, the coil winding method and the magnetic conducting mechanism. Two paths of currents i with equal amplitude and 90-degree phase difference are adopted_t1、i_t2By exciting the two layers of DD coils and combining the orthogonal position relationship of the two layers of DD coils, referring to fig. 3, the magnetomotive force generated by the two layers of coils in the DQDD coil can be respectively expressed as formula (1):

in the formula [ theta ]_sIs a reference spatial angle.

Then according to the fact that the two layers of DD have the same structure and the same number of turns, the magnetomotive force amplitude satisfies F_φ1＝F_φ2Then a magnetomotive force f is synthesized_tCan be simplified to formula (2), which means that the resultant magnetomotive force f_tPeriodically rotating at an amplitude such as an angular frequency omega.

f_t＝F_φ1cos(ωt-θ_s) (2)

The circular area where the rotary magnetomotive force is located and the square magnetic conducting mechanism have a circumscribed relation in position, as shown in fig. 3, so that the magnetic resistance corresponding to the synthetic magnetic flux distribution path is equal. This indicates that the resultant magnetic field also rotates periodically with constant amplitude at frequency ω.

FIG. 4 is a circuit diagram of a WPT system based on DQDD magnetic coupling mechanism, which is mainly composed of a DC power supply (U)_dc) The system comprises two groups of parallel full-bridge inverters (a first full-bridge inverter and a second full-bridge inverter), two LCC transmitting end compensating circuits (a first LCC transmitting compensating circuit and a second LCC transmitting compensating circuit), a DQDD magnetic coupling mechanism, two receiving end compensating circuits (a first capacitance resonance network and a second capacitance resonance network), two groups of series rectifier and filter circuits (a first full-bridge rectifier circuit and a second full-bridge rectifier circuit) and a load equivalent resistor R_LAnd (4) forming. First DD type transmitting coil L_t1The first wireless energy transmitting channel is connected with the first full-bridge inverter and the first LCC transmitting compensation circuit; second DD type transmitting coil L_t2The second wireless energy transmitting channel is connected with a second full-bridge inverter and a second LCC transmitting compensation circuit; first DD type reception coil L_r1The first capacitor resonance network is connected with a first wireless energy receiving channel formed by the first full-bridge rectifier circuit; second DD type receiving coil L_r2And the second wireless energy receiving channel is connected with a second wireless energy receiving channel formed by the second capacitor resonance network and the second full-bridge rectifying circuit.

The system converts a direct-current power supply into two paths of high-frequency alternating-current voltages u with equal amplitudes and 90-degree phase angle difference by controlling driving signals of two groups of high-frequency inverters₁、u₂Then the electric energy is supplied to two transmitting coils of the DQDD magnetic coupling mechanism through an LCC resonant circuit at a transmitting end, the receiving coil picks up the electric energy and then is connected into a rectifying circuit through a series compensation capacitor, and finally the electric energy is supplied to a load equivalent resistor R_L. L in FIG. 4_fti、C_ftiAnd C_ti(i ═ 1,2) are resonant elements that form a two-way LCC network, C_rj(j is 1,2) is a resonance capacitance of the receiving end, L_tiAnd L_rjSelf-inductance, M, of the respective coils of the DQDD transmitting and receiving terminals, respectively_tirj、M_rjtiAnd (i ═ 1,2, j ═ 1,2, i ≠ j) represents the mutual inductance of the coil corresponding to the transmitting end and the receiving end.

The speed of the change of the coupling coefficient along with the dislocation condition of the magnetic coupling mechanism is an important index for measuring the anti-offset capability of the magnetic coupling mechanism. Taking the open-circuit voltage and short-circuit current circuit diagram of the single-channel WPT pickup end shown in FIG. 5 as an example, the coupling coefficient of the magnetic coupling mechanism with only a single channel is calculated as shown in the following formula (3), V_ocFor open circuit voltage at the pickup terminal, I_scFor picking up uncompensated short-circuit currents at terminals, S_usFor uncompensated output capacity, S_upThe capacity of the transmitting coil is shown, omega is the angular frequency of the power supply, k is the equivalent coupling coefficient of the multi-channel magnetic coupling mechanism, and all voltage and current are phasors.

Similarly, as shown in the open-circuit voltage and short-circuit current circuit diagram of the multi-channel WPT pickup terminal shown in fig. 6, the equivalent coupling coefficient of the multi-channel magnetic coupling mechanism is obtained by using the magnetic coupling mechanism of the present embodiment and neglecting the same-side coupling. As shown in the following formula (4), wherein I_sc1、I_sc2Respectively, the short-circuit current, V, of the pickup terminal without compensation_oc1、V_oc2For open circuit voltage at the pick-up terminal, S_us1、S_us2Respectively, the output capacity, S, without compensation_up1、S_up2The capacity of the transmitting coil, omega the angular frequency of the power supply, and all voltage and current are phasors. In the formula (4) I_t1And I_t2When the phase difference is 90 DEG, k_effIs the equivalent coupling coefficient of the multi-channel magnetic coupling mechanism.

Let I_t2|²/|I_t1|²α, k_effThe expression is subjected to the following two-step simplification process to obtain the following formulas (5) and (6), respectively:

the function F (α) is then derived to give the following formula (7):

from the above formula (7), it can be obtained that the relationship between self-inductance and mutual inductance can be adjusted by adjusting I_t1And I_t2The amplitude ratio causes the equivalent coupling coefficient of the magnetic coupling mechanism to increase. With respect to the magnetic coupling mechanism proposed in this embodiment, since the self-inductance of each of the transmitting and receiving coils is very close, the following equation (8) is obtained by performing simplified processing on equation (7).

As seen from the above equation (8), when the sum of squares of the mutual inductances between the transmitter coil 1 and the two receiver coils is larger than the sum of squares of the mutual inductances between the transmitter coil 2 and the two receiver coils, the equivalent coupling coefficient can be increased by decreasing α, and vice versa. In the magnetic coupling mechanism provided in this embodiment, the phase difference of the currents between the transmitting coils is 90 °, the current amplitude ratio is 1, that is, the two excitation currents introduced into the second DD type transmitting coil and the first DD type transmitting coil have equal amplitudes and 90 ° phase difference, and at this time, a rotating magnetic field is formed in the orthogonal overlapping region of the second DD type transmitting coil and the first DD type transmitting coil, as shown in fig. 3.

In view of the magnetic coupling mechanism shown in fig. 1 and 2, because the phase difference between the two layers of DD-type coils is 90 ° in space, if the amplitude of the current flowing through the coils is equal and the phase difference is 90 °, the DQDD coil will form a rotating magnetic field on the XOY horizontal plane, so that the magnetic field distribution excited by the transmitting coil is more uniform, thereby improving the anti-offset performance of the magnetic coupling mechanism.

Table 1 shows the size parameters and the optimization range to be optimized for the DQDD magnetic coupling mechanism.

TABLE 1 size parameters to be optimized, optimization Range

Parameter(s)	Optimized range
		Distance D between coils of same layer D type1/mm	0～300
Side length W of square ferrite2/mm	60～400
		Thickness h of square ferrite2/mm	3～30

In order to determine a final optimized value, an embodiment of the present invention further provides a parameter design method for a wireless power supply coupling mechanism based on a quadrature DD type coil, including the steps of:

s1, setting all D-type coils to keep the same size and the same number of turns (of course, the structures and the parameters of the first wireless energy transmitting channel and the second wireless energy transmitting channel are not changed, and the structures and the parameters of the first wireless energy receiving channel and the second wireless energy receiving channel are not changed);

s2, setting the thickness h of the square ferrite plate₂At an initial value, set d₁Gradually increased and side length W of the square ferrite plate₂Following d₁Increase of the voltage, increase of the voltage synchronously, recording the self-inductance of the DD-type coil, the mutual inductance between the DD-type coils, and the system equivalent coupling systemThe variation of the number and d is determined according to the variation₁The optimum value of (d);

s3, setting h₂At an initial value, d₁Taking its optimal value, setting W₂Gradually increasing, recording the variation of the equivalent coupling coefficient of the system, and determining W according to the variation₂The optimum value of (d);

s4, setting d₁Take its optimum value, W₂Taking the optimal value, setting h₂Gradually increasing, recording the variation of the equivalent coupling coefficient of the system, and determining h according to the variation₂The optimum value of (d);

s5, setting parameters of the wireless power supply coupling mechanism as follows: d₁Take its optimum value, W₂Taking the optimal value h₂And taking the optimal value.

First, in step S2, the distance D between the coils in the same layer D-shape in terms of the relative positions of the coils₁As optimization variables, the distance between D-shaped coils in the same layer and the change rule of self inductance, mutual inductance and coupling coefficient of the coils are discussed. In optimizing the distance between the D-coils of the same layer, the thickness of the ferrite is set to 9mm (initial value) for controlling the variables, and the side length W of the square ferrite₂With distance D between D-shaped coils of the same layer₁The synchronization is increased. From FIG. 7, the coil self-inductance (L) can be obtained_r1、L_r2、L_t1、L_t2) All following the distance d between coils in the same layer₁Increase, decrease first and then increase slightly; and mutual inductance (M) between coils_t1r1、M_t2r2) And system equivalent coupling coefficient (k)_eff) All following the distance d between coils in the same layer₁Increase, first increase and then slightly decrease; from this, it is determined that the optimal distance between coils in the same layer is when the equivalent coupling coefficient of the system is maximum, i.e. d₁The most preferable value of (2) is 90 mm. The left side in FIG. 7 corresponds to the inductance value and the right side corresponds to the coupling coefficient value.

Then, in step S3, the optimum distance between the coils is determined to be 90mm, the ferrite thickness is still 9mm as the initial value, and the side length of the square ferrite is optimized. As a result of the optimization, as shown in FIG. 8, it was found that the equivalent coupling coefficient was maximized when the ferrite had a size of 300X 300mm (i.e., the optimum value of the side length was 300 mm).

Finally, in step S4, the optimum distance between the coils is determined to be 90mm, the length and width of the ferrite is determined to be 300 × 300mm, and the thickness of the square ferrite is optimized. The optimization results are shown in fig. 9, and the equivalent coupling coefficient can be gradually increased firstly and then basically not increased any more as the thickness of the ferrite is increased. The practical limiting factors such as the manufacturing cost of the magnetic core, the basic size of magnetic coupling and the like are comprehensively considered, the thickness of the system with a larger equivalent coupling coefficient is selected, and the thickness of the ferrite is finally determined to be 10mm in the embodiment.

Therefore, the parameters obtained after the optimization of the wireless power supply coupling mechanism are as follows: d₁The optimal value of the powder is 90mm and W₂The optimal value is 300mm, h₂The optimum value was 10mm, as shown in Table 2 below.

TABLE 2 dimensional parameters to be optimized, optimization Range and optimization values

Parameter(s)	Optimized range	Optimized value
			Distance D between coils of same layer D type1/mm	0～300	90
Side length W of square ferrite2/mm	60～400	300
			Thickness h of square ferrite2/mm	3～30	10

To verify the anti-offset performance of the DQDD magnetic coupling mechanism proposed in this embodiment, the sizes of the magnetic coupling mechanisms of this embodiment are the same CP coil, DD coil and non-optimized DQDD magnetic coupling mechanism as comparison objects, and all coils keep the same number of turns (19 turns). From the following three aspects: and the XOY horizontal plane, vertical direction and vertical direction deflection are compared with the coupling coefficient keeping coefficients of the three magnetic coupling mechanisms.

FIG. 10-1 shows the structure diagrams (including dimensional parameters) of the CP coil and the DD coil, respectively, (a), (b), (c), and (d) in FIG. 10-2 show the CP coil, the DD coil, and the DQDD coil before optimization (d)₁The rest parameters are consistent with the optimized DQDD coil) and the coupling coefficient of the magnetic coupling mechanism keeps a coefficient diagram when the optimized DQDD coil deviates in the XOY horizontal plane. It can be seen from fig. 10-2(a) that the CP coil has stronger anti-offset capability in the XOY horizontal plane, but the coupling coefficient keeps decreasing faster and faster as the offset distance in the XOY horizontal plane increases; it can be seen from fig. 10-2(b) that the DD coil has a higher anti-shift capability only in the Y direction when shifted in the XOY horizontal plane; it can be seen from fig. 10-2(c) and fig. 10-2(d) that the bias resistance of the optimized DQDD coil is strongest in each direction of the XOY horizontal plane, and the range of variation of the equivalent coupling coefficient of the optimized DQDD coil is smallest when the bias occurs.

As shown in fig. 11, it can be seen that when the three magnetic coupling mechanisms are vertically shifted, the coupling coefficient retention rates of the CP coil and the DQDD coil are substantially the same, and the vertical anti-shift of the DD coil is the worst of the three, so that the optimized DQDD coil is improved in vertical anti-shift.

As shown in fig. 12, it is easy to see that, when three kinds of magnetic coupling mechanisms are deflected vertically, the coupling coefficients of the three kinds of magnetic coupling mechanisms are kept strongest and completely unchanged due to the high symmetry of the CP coils; secondly, when the DD coil deflects vertically, the variation range of the coupling coefficient keeping coefficient is maximum and is from 1 to 0; finally, the equivalent coupling coefficient retention rate of the optimized DQDD coil is basically consistent with that of the CP coil, and the optimized DQDD coil is slightly stronger in vertical deflection resistance than the DQDD coil before optimization.

In the practical application of the WPT technology, misalignment of the receiving mechanism and the transmitting mechanism is the most common. The self-inductance and mutual inductance of the coil can be changed when the magnetic coupling mechanism deviates, but the change range of the self-inductance is small, and the change condition of the mutual inductance of the optimized DQDD magnetic coupling mechanism in the deviation process of various conditions is researched. FIG. 13 shows that M is the offset of the receiving mechanism in the XOY horizontal plane_t1r1、M_t1r2、M_t2r1And M_t2r2The variation of (2).

It can be seen from FIG. 13 that M occurs when only X or Y direction shift occurs_t1r2And M_t2r1Almost 0, i.e., there is no cross-coupling of the system when only X or Y direction shifts occur; and M_t1r1And M_t2r2The change range is small when the DD coil is shifted along the X direction and the Y direction respectively, and the DD coil is verified to have strong anti-shifting capability only in one direction.

FIG. 14 shows that M is a vertical offset of the proposed magnetic coupling mechanism_t1r1、M_t1r2、 M_t2r1And M_t2r2The variation of (2). It can be seen from figure 14 that M is present when only a vertical offset occurs_t1r2And M_t2r1Almost 0, i.e., when only vertical offset occurs, the system has no cross coupling; in transmitting vertical offsets only M_t1r1And M_t2r1The voltage induced by the secondary winding is almost equal to the voltage induced by the primary winding if the primary winding is flowing current of the same magnitude.

As the proposed DQDD magnetic coupling mechanism is of a symmetrical structure about the X axis or the Y axis, the vertical deflection range only takes 0-90 degrees into consideration. It can be seen from figure 15 that M is present when only vertical deflection occurs_t1r2And M_t2r1Increases with increasing angle of vertical deflection, and M_t1r1And M_t2r2Smaller as the angle of vertical deflection increases. When vertical deflection occurs M_t1r1And M_t2r2The voltage induced in the secondary winding decreases, and M_t1r2And M_t2r1The voltage induced in the secondary coil is increased, namely the equivalent coupling coefficient can be maintained to be basically unchanged when vertical deflection occurs.

And combining the three-direction anti-offset performance comparison, the DQDD coil optimized in the anti-offset performance is optimal.

When the proposed magnetic coupling mechanism only generates X, Y or Z-direction deviation, the magnetic coupling mechanism only has M because the DD coil on the same side is always in a decoupling state, namely, under the condition of neglecting mutual inductance on the same side_t1r1And M_t2r2Two pairs of mutual inductances, and a system fundamental wave equivalent circuit is shown in figure 16 under the condition of neglecting the internal resistances of a compensation inductance, a coil and a capacitor. U shape₁、U₂For two groups of inverted output voltages, U is driven by controlling PWM driving signal generated by DSP₁、U₂Differing in phase by 90. L is_ft1And L_ft2To compensate for inductance, C_ft1、C_ft2、C_t1、 C_t2Resonant capacitance for two channels at the transmitting end, C_r1、C_r2Is the resonant capacitance of two channels at the receiving end, L_t1、L_t2、L_r1、L_r2Self-inductance, R, of DQDD coils, respectively₁And R₂Equivalent resistances of two energy transfer channels are respectively, and omega is a resonance angular frequency.

U in FIG. 16_t1、U_r1、U_t2And U_r2As shown in the following formula:

the equivalent resistance from a full bridge rectifier can be expressed as:

r is easily obtained by dividing voltage by a resistor₁、R₂：

On the primary side, respectively make L_t1And C_t1Equivalent self inductance in series with L_ft1Is equal to L_t2And C_t2Equivalent self inductance in series with L_ft2Are equal while respectively making L_ft1And C_ft1，L_ft2And C_ft2Resonant, on the secondary side, with L_r1And C_r1，L_r2And C_r2Resonance, namely:

writing the KVL equation to the circuit column of fig. 16, one obtains:

resonance condition and U according to the above formula₁、U₂The amplitudes are equal and the phase difference is 90 degrees, the current of each mesh can be solved:

from equation (14), if two compensation inductors L_ft2And L_ft1Is equal to_t1And I_t2The amplitudes are the same and the phase difference is 90. The fundamental voltage phasor by the inverter can be expressed as:

the simultaneous equations above can yield the input and output power of two channels, respectively:

it is to be noted that L in the above formula (16)_ft2And L_ft1Are equal. The total input-output power thus obtained is:

when the proposed magnetic coupling mechanism is shifted in other directions (except the above-mentioned directions), the magnetic coupling mechanism has cross coupling on different sides, and four pairs of mutual inductances, namely M, exist in the system_t1r1、M_t1r2、 M_t2r1And M_t2r2. The fundamental wave equivalent circuit of the system in this case is shown in fig. 17.

U in FIG. 17_t11、U_t12、U_r11、U_r12、U_t21、U_t22、U_r21And U_r22As shown in equation (18):

when there is cross coupling, since I is always made_t1And I_t2Keeping equal amplitude and 90-degree phase difference, realizing that the DQDD magnetic coupling mechanism forms a rotating magnetic field on the XOY horizontal plane to enhance the anti-deviation capability of the magnetic coupling mechanism, so that R₁、R₂Expressed as:

the resonance conditions of the circuit at this time are:

a, B, C and D in formula (20) are shown by the following formula (21):

writing the KVL equation to the circuit column of fig. 17, one obtains:

resonance condition and U according to the above formula₁、U₂The amplitudes are equal and the phase difference is 90 degrees, the current of each mesh can be solved:

from the above formula, it can be seen that if two compensation inductors L_ft2And L_ft1Is equal to_t1And I_t2The amplitude is the same and the phase difference is 90 degrees, so that the excitation current of the transmitting coil is constant, and the output voltage of the system is not influenced by the load. In conclusion, no matter the cross coupling LCC/S compensation circuit exists, the design requirement that the current flowing through the two transmitting coils has equal amplitude and 90-degree phase difference can be realized.

From L_ft2And L_ft1Equally, the simultaneous equations above can yield the input and output power of two channels, respectively:

e and F in the above formula (24) are represented by the following formula (25):

the total input-output power thus obtained is:

experimental verification is performed below for the case where the primary and secondary windings are not cross-coupled when the transmitting and receiving mechanisms are aligned, and are shifted only in the X or only Y direction. If the change of the self-inductance of the coil during the offset is neglected, a WPT system based on the DQDD coil is set up by using the circuit parameters shown in the table 3 and the coupling mechanism parameters shown in the table 4. The control chip is selected to be a TMS320F28335 type DSP, the switch tube is selected to be SiHB33N60E, the power diode is selected to be IDW20G65C5, the resistance mode output of IT8817B electronic load is used, and a RIGOL DS7054 oscilloscope is used for wave recording and current effective value measurement. The primary and secondary side coils are made by winding 0.1 multiplied by 300 strands of litz wire, and the number of turns of the primary and secondary side coils is 19. The distance between the transmitting coil and the receiving coil is 130 mm.

TABLE 3 System Experimental Circuit parameters

Parameter(s)	Value taking	Parameter(s)	Value taking
				Lt1/uH	262.92	Cft1/nF	72.95
Lt2/uH	275.71	Cft2/nF	72.9
				Lr1/uH	273.31	Ct1/nF	12.3
Lr2/uH	288.25	Ct2/nF	11.86
				Mt1r1/uH	50.1	Cr1/nF	10.2
Mt2r2/uH	51.07	Cr2/nF	9.7
				Lft1/uH	40.4	RL/Ω	50
Lft2/uH	40.5

TABLE 4 System coupling mechanism parameters

Parameter(s)	Value taking
		d1/mm	90
W2/mm	300
		h2/mm	10
W4/mm	150
		d	130

First, in FIGS. 18(A), (B), and (C), when the primary and secondary coils are opposed to each other, shifted by 100mm along X, and shifted by 100mm along Y, respectively, the output voltage (u) of the inverter is obtained₁And u₂) Output current (i)₁And i₂) Primary coil current (i)_t1And i_t2) Secondary side output voltage (u)_o1And u_o2) And secondary side output current (i)_r1And i_r2). The general formula of u in FIGS. 18(A) - (a), (B) - (a), (C) - (a)₁、u₂、i₁And i₂The waveform of (a) shows that soft switching is always achieved; from i in FIGS. 18(A) - (B), (B) - (B), (C) - (B)_t1And i_t2It can be seen that the current phases of the two transmitting coils are different by 90 degrees, and the amplitudes are basically equal; FIG. 1 shows a schematic view of aU in 8(A) - (C), (B) - (C), (C) - (C)_o1、u_o2、i_r1And i_r2And outputting voltage and current for the secondary side. The input power is 720W when the time is positive, the output power is 620W, and the system efficiency is 86.1%; when the X-direction deviation is 100mm, the input power is 630W, the output power is 540W, and the system efficiency is 85.7%; when the displacement is 100mm along the Y direction, the input power is 670W, the output power is 570W, and the system efficiency is 85.1 percent.

Then, in order to verify the system operation under the condition that the DQDD magnetic coupling mechanism has cross coupling, the present embodiment selects the general misalignment condition (offset amount: ═ 100mm,. And (4) establishing a WPT system based on the DQDD coil by using the circuit parameters shown in the table 5. By u in FIG. 19(a)₁、u₂、i₁And i₂The waveform of (a) shows that soft switching is always achieved; from i in FIG. 19(b)_t1And i_t2It can be seen that the current phases of the two transmitting coils are different by 90 degrees, and the amplitudes are basically equal; u in FIG. 19(c)_o1、u_o2And i_r2And outputting voltage and current for the secondary side. At this time, the input power is 630W, the output power is 520W, and the system efficiency is 82.5%.

TABLE 5 general positions taken for the experiments

Parameter(s)	Value taking	Parameter(s)	Value taking
				Lt1/uH	256.04	Lft2/uH	34.71
Lt2/uH	269.5	Cft1/nF	80.85
				Lr1/uH	271.27	Cft2/nF	82.19
Lr2/uH	280.93	Ct1/nF	10.33
				Mt1r1/uH	18.13	Ct2/nF	9.94
Mt2r2/uH	23.67	Cr1/nF	10.33
				Mt1r2/uH	6.21	Cr2/nF	9.94
Mt2r1/uH	20.76	RL/Ω	40
				Lft1/uH	34.15

Finally, experiments and simulations measure the equivalent coupling coefficient change conditions of the DQDD magnetic coupling mechanism in the XOY horizontal plane shift as shown in fig. 20 and 21, respectively, a comparison of results obtained in the Z-axis shift experiment and the simulation is shown in fig. 22, and a comparison of results obtained in the Z-axis deflection experiment and the simulation is shown in fig. 23.

The maximum relative error of the equivalent coupling coefficient and the simulation equivalent coupling coefficient is 10.97% and the minimum relative error is 0.025% through experiment, and the experiment result shows that the DQDD magnetic coupling mechanism has strong anti-offset performance. The overall size of the magnetic coupling mechanism is 390mm multiplied by 19mm, and the coupling coefficient is always kept above 40% on an XOY horizontal plane with the delta X being plus or minus 150mm and the delta Y being plus or minus 150 mm; keeping the coupling coefficient to be more than 40% in a vertical deviation range of 110-210 mm; the high symmetry of the DQDD magnetic coupling mechanism can be presumed to keep the coupling coefficient above 98% in the vertical deflection range of 0-360 degrees.

In summary, the present embodiment designs a magnetic coupling mechanism with strong anti-offset performance, and the magnetic coupling mechanism can be used in the field of wireless charging of electric vehicles, so as to satisfy the requirement of a large charging area during wireless charging of electric vehicles. Meanwhile, the DQDD magnetic coupling mechanism provided by the embodiment has more excellent anti-offset performance after being optimized, and the change conditions of system mutual inductance and equivalent coupling coefficient of the DQDD magnetic coupling mechanism provided by the embodiment under various offset conditions are analyzed; and the power distribution of the two energy channels under different coupling conditions according to the adopted double LCC/S compensation topology. In the experiment, the WPT system with the transmission distance of 130mm, the output power of 500W and the transmission efficiency of 82.5 percent or higher is realized.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.