A semi-analytical mutual inductance calculation method for dynamic wireless power transmission magnetic coupling mechanism

Abstract

This invention proposes a semi-analytical mutual inductance calculation method for dynamic wireless power transmission magnetic coupling mechanisms. During the design and optimization of the magnetic coupling mechanism, the mutual inductance calculation method described in this invention requires only one finite element simulation throughout the entire process. It can quickly calculate the mutual inductance of the magnetic coupling mechanism under different receiver positions and different receiver structural parameters. This solves the problems of excessive computation time, large simulation workload, excessive computer memory consumption, and unclear physical concepts inherent in traditional simulation methods for calculating mutual inductance in dynamic wireless power transmission magnetic coupling mechanisms, greatly improving the speed of mutual inductance calculation and the design speed of the magnetic coupling mechanism. Furthermore, the method described in this invention provides analytical functional relationships between various structural parameters of the receiver and the mutual inductance, revealing the influence of different structural parameters of the receiver on the mutual inductance, and can also provide theoretical guidance for the structural design of magnetic coupling mechanisms.

Description

Technical Field

[0001] This invention belongs to the field of wireless power transmission technology, and in particular relates to a semi-analytical mutual inductance calculation method for a dynamic wireless power transmission magnetic coupling mechanism. Background Technology

[0002] Dynamic wireless power transfer technology can effectively improve the driving range of electric vehicles, reduce charging time, and enhance the flexibility, safety, and environmental adaptability of vehicle charging, fundamentally solving the bottleneck problems currently restricting the promotion and application of electric vehicles. In a dynamic wireless power transfer system, the magnetic coupling mechanism is the core component for wireless electromagnetic energy transmission. Mutual inductance is the most important factor directly determining the output power of the magnetic coupling mechanism, and it is related to many parameters such as the structure and relative position of the transmitting and receiving coils, directly determining the key performance aspects of the dynamic wireless power transfer system. Therefore, the calculation of mutual inductance and the relationship between mutual inductance and various parameters of the magnetic coupling mechanism are key issues in the design process of the magnetic coupling mechanism.

[0003] Currently, there are two main methods for calculating mutual inductance in dynamic wireless power transfer magnetic coupling mechanisms. The first is the analytical calculation method, based on Biot-Savart's law, which calculates mutual inductance by calculating the mutual flux passing through the coil. For example, the literature [S. Raju, R. Wu, M. Chan and CP Yue, "Modeling of Mutual Coupling Between Planar Inductors in Wireless Power Applications," IEEE Transactions on Power Electronics, 2014] provides a method for calculating the mutual inductance of a circular hollow coil based on the Neumann equation. However, the analytical calculation method is only applicable to magnetic coupling mechanisms without a magnetic core. When the structure of the magnetic core or coil is complex, the magnetic field distribution is difficult to describe by formulas, making analytical calculation of mutual inductance impossible. The second method is the finite element method (FEM). This method uses finite element simulation software to obtain mutual inductance through simulation. The simulation method can calculate the mutual inductance in complex magnetic coupling mechanisms and is widely used in dynamic wireless power transfer systems. However, in the design or optimization of magnetic coupling mechanisms, the finite element method requires parametric scanning simulation to obtain the relationship between mutual inductance and the structural parameters of the magnetic coupling mechanism. The need for thousands of 3D field simulations consumes a significant amount of computer memory and time, greatly increasing the design cycle. Furthermore, this method cannot establish a quantitative relationship between mutual inductance and structural parameters, leaving the design of magnetic coupling mechanisms without theoretical guidance. Summary of the Invention

[0004] The purpose of this invention is to address the problems of large simulation workload, slow calculation speed, and lack of theoretical basis in the traditional finite element method for calculating mutual inductance of existing dynamic wireless power transmission magnetic coupling mechanisms. This invention proposes a semi-analytical mutual inductance calculation method for dynamic wireless power transmission magnetic coupling mechanisms.

[0005] This invention is achieved through the following technical solution: This invention proposes a semi-analytical mutual inductance calculation method for a dynamic wireless power transfer magnetic coupling mechanism, the method specifically comprising:

[0006] Step 1: Establish finite element simulation models of the transmitting core and transmitting coil. Obtain the rated transmitting current excitation I through a single finite element simulation. T Below is the simulated distribution of magnetic induction intensity B generated by the transmitting coil on the lines x=0 and y=0 of the receiving end plane z=h; the receiving end plane refers to the horizontal plane where the receiving coil is located, i.e., the xy plane, and the rated transmitting current I. T For the magnetic coupling mechanism to operate under rated conditions, the current i in the transmitting coil T The effective value of h is the vertical distance between the upper surface of the transmitter and the plane of the receiver.

[0007] Step 2: Extract the vertical component B of the magnetic field strength on the receiving end plane. z Furthermore, the vertical component B of the magnetic induction intensity on the receiving end plane was extracted using numerical analysis software. z The maximum value of the magnetic field shape function λ is obtained by fitting the Gaussian function;

[0008] Magnetic flux density is a spatial vector with direction, which can be decomposed into a horizontal component B along the x, y, and z axes. x B y and vertical component B z ;

[0009] Step 3: Substitute the position x of the receiving coil on the x-axis to solve for the mutual inductance position function M. x (x);

[0010] Step 4: Incorporate the length l of the receiving coil R Solve for the mutual inductance length function M l (l R );

[0011] Step 5: Incorporate the width W of the receiving coil R Solve for the mutual inductance width function M W (W R );

[0012] Step 6: Incorporate the number of turns N of the receiving coil R Find the mutual inductance turns function M. N (NR );

[0013] Step 7: Substitute the number of receiving coils n and the center distance d between two adjacent receiving coils to solve for the mutual inductance spacing function M. dn (d,n);

[0014] Step 8: Substitute the length of the receiving end flat magnetic core into the solution to calculate the mutual inductance core function M. core (l c W c The size of the receiving end magnetic core should be larger than the outer dimensions of the multiple receiving coils;

[0015] Step 9: Solve for the mutual inductance M of the magnetic coupling mechanism by multiplying the amplitude of the vertical component of the magnetic induction intensity with each mutual inductance calculation function. The specific expression for the solution is as follows:

[0016]

[0017] Step 10: When the position of the receiving end and the structural parameters of the receiving coil and the receiving end magnetic core change, substitute the new structural parameters and position parameters into steps 3 to 9 to calculate the mutual inductance under the new structural parameters.

[0018] Furthermore, the semi-analytical calculation method is applicable to longitudinal flux-type magnetic coupling mechanisms, that is, magnetic coupling mechanisms in which the transmitting coil generates an unloaded magnetic field to form N and S alternating magnetic poles along the direction of travel, and the direction of the main magnetic flux is parallel to the direction of travel.

[0019] Furthermore, the mutual inductance position function M x (x) represents the functional relationship between mutual inductance and the position of the receiving coil, and its expression satisfies:

[0020]

[0021] Where τ represents the pole pitch of the transmitting coil, that is, the distance between two adjacent equivalent magnetic poles in the magnetic field generated by the transmitting coil.

[0022] Furthermore, the mutual inductance length function represents the functional relationship between mutual inductance and the length of the receiving coil, and its expression is as follows:

[0023]

[0024] Furthermore, the mutual inductance width function represents the functional relationship between mutual inductance and the width of the receiving coil, and its expression is as follows:

[0025]

[0026] Where Φ(x) represents the distribution function of the standard normal distribution.

[0027] Furthermore, the mutual inductance turns function represents the functional relationship between mutual inductance and the number of turns of the receiving coil, and its expression is as follows:

[0028]

[0029] Where i represents the i-th turn of the receiving coil, and δ represents the turn spacing between two adjacent turns of the receiving coil.

[0030] Furthermore, the mutual inductance spacing function represents the functional relationship between the mutual inductance, the number of receiving coils, and the center distance between two adjacent receiving coils, and its expression is as follows:

[0031]

[0032] Furthermore, the mutual inductance core function represents the functional relationship between mutual inductance and the structural parameters of the receiving end flat plate core, and its expression is as follows:

[0033]

[0034] The beneficial effects of this invention are as follows:

[0035] This invention proposes a semi-analytical mutual inductance calculation method for dynamic wireless power transmission magnetic coupling mechanisms. During the design and optimization of the magnetic coupling mechanism, the mutual inductance calculation method described in this invention requires only one finite element simulation throughout the entire process. It can quickly calculate the mutual inductance of the magnetic coupling mechanism under different receiver positions and different receiver structural parameters. This solves the problems of excessive computation time, large simulation workload, excessive computer memory consumption, and unclear physical concepts inherent in traditional simulation methods for calculating mutual inductance in dynamic wireless power transmission magnetic coupling mechanisms, greatly improving the speed of mutual inductance calculation and the design speed of the magnetic coupling mechanism. Furthermore, the method described in this invention provides analytical functional relationships between various structural parameters of the receiver and the mutual inductance, revealing the influence of different structural parameters of the receiver on the mutual inductance, and can also provide theoretical guidance for the structural design of magnetic coupling mechanisms. Attached Figure Description

[0036] Figure 1 This is a flowchart of the semi-analytical mutual inductance calculation method described in this invention;

[0037] Figure 2 This is a schematic diagram of the longitudinal flux-type magnetic coupling mechanism (with a single receiving coil at the receiving end) to which the calculation method described in this invention is applicable;

[0038] Figure 3 for Figure 2 The main view;

[0039] Figure 4This is a schematic diagram of the longitudinal flux-type magnetic coupling mechanism (with multiple receiving coils connected in series at the receiving end) to which the calculation method described in this invention is applicable;

[0040] Figure 5 for Figure 4 The main view;

[0041] Figure 6 A schematic diagram of the structural parameters when the receiver uses a series connection of multiple receiving coils.

[0042] Figure 7 The transmitting coil of the present invention generates a magnetic induction intensity B on the straight line x = 0 on the receiving end plane (z = h). z The simulation distribution results are shown in the figure.

[0043] Figure 8 The transmitting coil of the present invention generates a magnetic induction intensity B on the straight line y = 0 on the receiving end plane (z = h). z The simulation distribution results are shown in the figure. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] As attached Figure 1 As shown, the semi-analytical mutual inductance calculation method for the dynamic wireless power transfer magnetic coupling mechanism of the present invention comprises 10 basic steps. This semi-analytical calculation method for the dynamic wireless power transfer magnetic coupling mechanism of the present invention is applicable to... Figure 2 - Appendix Figure 5 The longitudinal flux-type magnetic coupling mechanism shown is a magnetic coupling mechanism in which the transmitting coil generates an unloaded magnetic field that forms alternating N and S magnetic poles along the direction of travel, and the direction of the main magnetic flux is parallel to the direction of travel. (See attached image) Figure 2 To be continued Figure 5 Only a schematic diagram of the transmitter using an N-type guide rail magnetic core is given. The method described in this invention is also applicable to other structures, such as those using an I-type guide rail, an S-type guide rail, or an N-type guide rail magnetic core.

[0046] Combination Figures 1-8 This invention proposes a semi-analytical mutual inductance calculation method for a dynamic wireless power transfer magnetic coupling mechanism, the method specifically including:

[0047] Step 1: Based on whether the receiver uses a single-receiving coil structure or a multi-receiving coil structure, establish an auxiliary... Figure 2 Or attached Figure 4 Finite element simulation models of the transmitting core and transmitting coil were used to obtain the rated transmitting current excitation I through a single finite element simulation. T Below is the simulated distribution of magnetic induction intensity B generated by the transmitting coil on the lines x=0 and y=0 of the receiving end plane z=h; the receiving end plane refers to the horizontal plane where the receiving coil is located, i.e., the xy plane, and the rated transmitting current I. T For the magnetic coupling mechanism to operate under rated conditions, the current i in the transmitting coil T The effective value of h is the vertical distance between the upper surface of the transmitter and the plane of the receiver.

[0048] Step 2: Extract the vertical component B of the magnetic field strength on the receiving end plane. z The distribution results of the lines x=0 and y=0 in the receiving plane (z=h) are shown in the attached figure. Figure 7 and attached Figure 8 As shown, the vertical component B of the magnetic induction intensity on the receiving end plane is extracted by performing sine function fitting and Gaussian function fitting using numerical analysis software. z The maximum value B z-max Furthermore, a magnetic field shape function λ is proposed by fitting a Gaussian function.

[0049] Magnetic flux density is a spatial vector with direction, which can be decomposed into a horizontal component B along the x, y, and z axes. x B y and vertical component B z ; as attached Figure 3 As shown, due to the horizontal component B of the magnetic induction intensity x B y Since it does not pass through the receiving coil, it has no effect on the calculation of mutual inductance. To simplify the analysis, only the vertical component of the magnetic induction intensity needs to be considered.

[0050] Step 3: Substitute the position x of the receiving coil on the x-axis to solve for the mutual inductance position function M. x (x);

[0051] The mutual inductance position function M x (x) represents the functional relationship between mutual inductance and the position of the receiving coil, and its expression satisfies:

[0052]

[0053] Where τ represents the pole pitch of the transmitting coil, that is, the distance between two adjacent equivalent magnetic poles in the magnetic field generated by the transmitting coil.

[0054] Step 4: Incorporate the length l of the receiving coil R Solve for the mutual inductance length function M l (l R );

[0055] The mutual inductance length function represents the functional relationship between mutual inductance and the length of the receiving coil, and its expression is as follows:

[0056]

[0057] Step 5: Incorporate the width W of the receiving coil R Solve for the mutual inductance width function M W (W R );

[0058] The mutual inductance width function represents the functional relationship between mutual inductance and the width of the receiving coil, and its expression is as follows:

[0059]

[0060] Where Φ(x) represents the distribution function of the standard normal distribution.

[0061] Step 6: Incorporate the number of turns N of the receiving coil R Find the mutual inductance turns function M. N (N R );

[0062] The mutual inductance turns function represents the functional relationship between mutual inductance and the number of turns of the receiving coil, and its expression is as follows:

[0063]

[0064] Where i represents the i-th turn of the receiving coil, and δ represents the turn spacing between two adjacent turns of the receiving coil.

[0065] Step 7: Substitute the number of receiving coils n and the center distance d between two adjacent receiving coils to solve for the mutual inductance spacing function M. dn (d,n); a schematic diagram of the multi-coil series receiver structure is attached. Figure 6 As shown, when the receiver uses a single receiving coil structure, the mutual inductance spacing function M dn (d,n)=1;

[0066] The mutual inductance spacing function represents the functional relationship between the mutual inductance, the number of receiving coils, and the center distance between two adjacent receiving coils, and its expression is as follows:

[0067]

[0068] Step 8: Substitute the length of the receiving end flat magnetic core into the solution to calculate the mutual inductance core function M. core (l c W c The size of the receiving end magnetic core should be larger than the outer dimensions of the multiple receiving coils;

[0069] The mutual inductance core function represents the functional relationship between mutual inductance and the structural parameters of the receiving end flat plate core, and its expression is as follows:

[0070]

[0071] Step 9: Solve for the mutual inductance M of the magnetic coupling mechanism by multiplying the amplitude of the vertical component of the magnetic induction intensity with each mutual inductance calculation function. The specific expression for the solution is as follows:

[0072]

[0073] Step 10: When the position of the receiving end and the structural parameters of the receiving coil and the receiving end magnetic core change, substitute the new structural parameters and position parameters into steps 3 to 9 to calculate the mutual inductance under the new structural parameters.

[0074] This invention proposes a semi-analytical mutual inductance calculation method for dynamic wireless power transmission magnetic coupling mechanisms. This method uses mutual inductance calculation functions such as mutual inductance position function, mutual inductance length function, mutual inductance width function, and mutual inductance turns function to establish the functional relationship between mutual inductance and the receiver position and various structural parameters. This simplifies the integration of magnetic flux density during mutual inductance calculation to the product of each mutual inductance calculation function and the magnetic flux density amplitude, thereby reducing computational difficulty and increasing calculation speed. In the design and optimization of the magnetic coupling mechanism, only one finite element simulation is required. By changing the values ​​of each mutual inductance calculation function to replace parametric scanning simulation, the mutual inductance of receivers with different structures at arbitrary positions can be quickly calculated. The semi-analytical calculation method described in this invention solves the problems of excessively long calculation time, large simulation workload, and excessive computer memory consumption in the traditional simulation calculation method for dynamic wireless power transmission magnetic coupling mechanisms, greatly improving the speed of mutual inductance calculation and the design speed of magnetic coupling mechanisms.

[0075] The semi-analytical mutual inductance calculation method for a dynamic wireless power transmission magnetic coupling mechanism proposed in this invention has been described in detail above. Specific examples have been used to illustrate the principle and implementation of this invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A semi-analytical mutual inductance calculation method for a dynamic wireless power transfer magnetic coupling mechanism, characterized in that: The method specifically includes: Step 1: Establish finite element simulation models of the transmitting core and transmitting coil. Obtain the rated transmitting current excitation I through a single finite element simulation. T Below is the simulated distribution of magnetic induction intensity B generated by the transmitting coil on the lines x=0 and y=0 of the receiving end plane z=h; the receiving end plane refers to the horizontal plane where the receiving coil is located, i.e., the xy plane, and the rated transmitting current I. T For the magnetic coupling mechanism to operate under rated conditions, the current i in the transmitting coil T The effective value of h is the vertical distance between the upper surface of the transmitter and the plane of the receiver. Step 2: Extract the vertical component B of the magnetic field strength on the receiving end plane. z Furthermore, the vertical component B of the magnetic induction intensity on the receiving end plane was extracted using numerical analysis software. z The maximum value of the magnetic field shape function λ is obtained by fitting the Gaussian function; Magnetic flux density is a spatial vector with direction, which can be decomposed into a horizontal component B along the x, y, and z axes. x B y and vertical component B z ; Step 3: Substitute the position x of the receiving coil on the x-axis to solve for the mutual inductance position function M. x (x); Step 4: Incorporate the length l of the receiving coil R Solve for the mutual inductance length function M l (l R ); Step 5: Incorporate the width W of the receiving coil R Solve for the mutual inductance width function M W (W R ); Step 6: Incorporate the number of turns N of the receiving coil R Find the mutual inductance turns function M. N (N R ); Step 7: Substitute the number of receiving coils n and the center distance d between two adjacent receiving coils to solve for the mutual inductance spacing function M. dn (d,n); Step 8: Substitute the length of the receiving end flat magnetic core into the solution to calculate the mutual inductance core function M. core (l c W c The size of the receiving end magnetic core should be larger than the outer dimensions of the multiple receiving coils; Step 9: Solve for the mutual inductance M of the magnetic coupling mechanism by multiplying the amplitude of the vertical component of the magnetic induction intensity with each mutual inductance calculation function. The specific expression for the solution is as follows: Step 10: When the position of the receiving end and the structural parameters of the receiving coil and the receiving end magnetic core change, substitute the new structural parameters and position parameters into steps 3 to 9 to calculate the mutual inductance under the new structural parameters.

2. The method according to claim 1, characterized in that, The semi-analytical calculation method is applicable to longitudinal flux-type magnetic coupling mechanisms, that is, magnetic coupling mechanisms in which the transmitting coil generates an unloaded magnetic field to form N and S alternating magnetic poles along the direction of travel, and the direction of the main magnetic flux is parallel to the direction of travel.

3. The method according to claim 1, characterized in that, The mutual inductance position function M x (x) represents the functional relationship between mutual inductance and the position of the receiving coil, and its expression satisfies: Where τ represents the pole pitch of the transmitting coil, that is, the distance between two adjacent equivalent magnetic poles in the magnetic field generated by the transmitting coil.

4. The method according to claim 1, characterized in that, The mutual inductance length function represents the functional relationship between mutual inductance and the length of the receiving coil, and its expression is as follows:

5. The method according to claim 1, characterized in that, The mutual inductance width function represents the functional relationship between mutual inductance and the width of the receiving coil, and its expression is as follows: Where Φ(x) represents the distribution function of the standard normal distribution.

6. The method according to claim 1, characterized in that, The mutual inductance turns function represents the functional relationship between mutual inductance and the number of turns of the receiving coil, and its expression is as follows: Where i represents the i-th turn of the receiving coil, and δ represents the turn spacing between two adjacent turns of the receiving coil.

7. The method according to claim 1, characterized in that, The mutual inductance spacing function represents the functional relationship between the mutual inductance, the number of receiving coils, and the center distance between two adjacent receiving coils, and its expression is as follows:

8. The method according to claim 1, characterized in that, The mutual inductance core function represents the functional relationship between mutual inductance and the structural parameters of the receiving end flat plate core, and its expression is as follows:

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