A Design Method for the Receiver Configuration in a Dynamic Wireless Power Supply System for Electric Vehicles

Abstract

The present invention provides a design method for the receiver configuration in an electric vehicle dynamic wireless power supply system. The method specifically includes four parts: determination of design indicators and limiting conditions, calculation of electrical parameters, design of structural parameters, and performance verification. This method combines the advantages of traditional analytical design methods and finite element design methods, is applicable to the dynamic wireless power supply electromagnetic coupling mechanism with a complex magnetic core structure, and solves the problem of narrow applicability in traditional analytical design methods. At the same time, it can provide theoretical guidance for the design of receiver structural parameters, such as the length of the receiving coil, the width of the receiving coil, the connection method of multiple receiving coils, the center distance of multiple receiving coils, and the size of the receiver magnetic core. Only a few simulations are required throughout the design process, which solves the problems of narrow applicability in traditional analytical design methods and slow design cycles in traditional finite element simulation design methods, and provides theoretical design guidance for the selection of main structural parameters in the structural design process of the receiver.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless power transmission, and particularly relates to a design method for the receiving end configuration in a dynamic wireless power supply system for electric vehicles. Background Art

[0002] The proposal of dynamic wireless power supply technology provides a fundamental solution to the bottleneck problems of electric vehicles, such as short driving range and frequent parking for charging. Different from the "one-to-one" charging mode in the static wireless power supply system, the dynamic system adopts a "one-to-many" working mode, that is, a single transmitter needs to transmit energy to the receiving ends of multiple vehicles driving above the road surface at the same time. However, different vehicle models, such as electric vehicles and electric buses, have different requirements for output power, output voltage, and transmission distance. Since the power supply guide rail of the transmitter cannot be changed after construction is completed, in order to ensure that all vehicles can be charged normally above the transmitting guide rail, it is necessary to independently design the receiving end according to the technical indicators of different vehicles. Therefore, the design of the receiving end is a key issue in dynamic wireless power supply technology.

[0003] There are mainly two design methods for the receiving end configuration in the dynamic wireless power supply system, namely the analytical design method and the finite element design method. The analytical design method has a clear design idea and can clearly give the analytical relationship between design indicators such as output power and the structural parameters of the receiving end. However, the existing analytical design method is only applicable to the hollow coil structure or the structure with a simple magnetic core configuration. For the dynamic magnetic coupling mechanism with a complex magnetic core structure, the finite element design method is mostly used for the receiving end at present. However, the finite element design method relies too much on parametric scanning during the design process, with a large amount of simulation work and a long design time. In addition, this method lacks a systematic design idea and cannot provide theoretical guidance for the selection of each structural parameter of the receiving end. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems in the existing dynamic wireless power supply system for electric vehicles, such as the long design cycle, large amount of simulation work, lack of systematic design idea, and lack of theoretical design guidance caused by the over-reliance on finite element simulation in the design of the receiving end configuration, and to propose a design method for the receiving end configuration in a dynamic wireless power supply system for electric vehicles.

[0005] The present invention is realized through the following technical solutions. The present invention proposes a design method for the receiving end configuration in a dynamic wireless power supply system for electric vehicles, and the method specifically includes four parts: determination of design indicators and limiting conditions, calculation of electrical parameters, design of structural parameters, and performance verification;

[0006] The determination of the above-mentioned design indicators and limiting conditions specifically includes two steps: The first step is to calculate the design indicators of output power, output voltage, and transmission efficiency based on the battery and chassis height parameters of the electric vehicle; the second step is to determine the limiting conditions during the design process based on the chassis installation space and side shift requirements, providing constraints for the subsequent design of the electrical and structural parameters of the receiving end;

[0007] The calculation of the above-mentioned electrical parameters specifically includes three steps: The first step is to calculate the equivalent resistance R e and the receiving coil current I S ; The second step is to determine the maximum internal resistance r s-max allowed for the receiving coil according to the design indicators; The third step is to calculate the open-circuit voltage U oc-need required for the receiving coil and the required mutual inductance M need ;

[0008] The design of the above-mentioned structural parameters specifically includes four steps: The first step is to obtain the magnetic field distribution of the power supply guide rail on the receiving end plane through a single finite element simulation, obtaining the magnetic flux density amplitude B z-max and the shape parameter σ, providing a reference for the subsequent mutual inductance calculation and coil width design; The second step is to complete the design of the coil length, coil width, coil connection method, and coil center distance in sequence according to the structural parameter design criteria with the chassis size and offset performance limiting conditions as constraints; The third step is to select the receiving end core size based on the coil size and calculate the mutual inductance for a single-turn receiving coil; The fourth step is to determine the wire diameter based on the calculated receiving current and complete the turn number design of the receiving coil according to the required mutual inductance; Thus, the preliminary design of the structure of the receiving end is completed;

[0009] The performance verification specifically includes two steps: The first step is to build a simulation model based on the preliminary design results for a single simulation to complete the magnetic saturation verification; The second step is to conduct the receiving end efficiency verification. If the design indicators are met, the design is completed; otherwise, return to the structural parameter design part to readjust the structural parameters.

[0010] Furthermore, the equivalent resistance R e and the receiving coil current I S are calculated from Equations (1) and (2); The maximum internal resistance r s-max allowed for the receiving coil is determined from Equation (3); The open-circuit voltage U oc-need required for the receiving coil and the required mutual inductance M need are calculated from Equations (4) and (5);

[0011] The expressions of Equations (1) to (5) are as follows:

[0012] R e =(8 / π 2 )·R L =(8 / π 2)·(U o / I o ) (1)

[0013] wherein, R L is the equivalent load of the battery; R e is the load resistance R L after the uncontrolled rectifier current; U o is the charging voltage of the battery; I o is the charging current of the battery;

[0014]

[0015]

[0016] wherein, η is the transmission efficiency index of the receiving end;

[0017]

[0018]

[0019] wherein, I p is the effective value of the current in the transmitting coil.

[0020] Furthermore, the receiving end efficiency verification is carried out by Equation (6), and the expression of Equation (6) is as follows:

[0021]

[0022] wherein, I s is the effective value of the current in the receiving coil; r s is the calculated internal resistance of the receiving coil after design completion.

[0023] Furthermore, the design criteria of the structural parameters include the design criteria for the length of the receiving coil, the design criteria for the width of the receiving coil, the design criteria for the connection method of multiple receiving coils, the design criteria for the center distance of multiple receiving coils, and the design criteria for the magnetic core at the receiving end.

[0024] Furthermore, the design criteria for the length of the receiving coil are specifically as follows:

[0025] During the design process of the receiving end, the length l coil of the receiving coil should satisfy:

[0026] 0.75τ ≤ l coil ≤ τ (7)

[0027] The specific value of the length l coil of the receiving coil is determined by the weights of the output power and the power per unit length; when the weight requirement for the power density is high, the coil length should be reduced, and the length l coilThe value of coil is close to 0.75τ; when the weight requirement for the output power is high, the coil length should be increased, and the length l of the receiving coil

[0028] Furthermore, the design criterion for the width of the receiving coil is specifically as follows:

[0029] During the design process of the receiving end, the width w of the receiving coil coil should satisfy:

[0030] 2.8σ ≤ w coil ≤ 6σ (8)

[0031] The specific value of the width w of the receiving coil coil is determined by the output power and the weight of the width-to-power ratio.

[0032] Furthermore, the design criterion for the connection method of the multiple receiving coils is specifically as follows:

[0033] (i) When -0.5τ + 2kτ ≤ d c ≤ 0.5τ + 2kτ, where k is a natural number, and d c is the center distance between two adjacent receiving coils. In order to maximize the output power of the receiving coil, the winding directions of two adjacent receiving coils should be the same, that is, the adjacent receiving coils are connected in series forward;

[0034] (ii) When 0.5τ + 2kτ < d c ≤ 1.5τ + 2kτ, in order to maximize the output power of the receiving coil, the winding directions of two adjacent coils should be opposite, that is, the adjacent receiving coils are connected in series reversely.

[0035] Furthermore, the design criterion for the center distance of the multiple receiving coils is specifically as follows:

[0036] During the design process of the receiving end with a multi-coil structure, the center distance d of the multiple receiving coils is made to satisfy d c = τ to maximize the output power; when the installation space on the vehicle chassis is limited, the center distance d of the multiple receiving coils satisfies d c = l coil , sacrificing the output voltage appropriately to reduce the total length and meet the installation space requirements.

[0037] Furthermore, the design criterion for the magnetic core of the receiving end is specifically as follows:

[0038] The magnetic core of the receiving end uses a flat magnetic core made of soft ferrite material, and the length l of the magnetic core core satisfies: l receiver ≤ l core ≤ 1.3l receiver where l receiver is the total length of the multiple receiving coils; the width w of the magnetic corecore Satisfy: w coil ≤ w core ≤ 1.1w coil , where the core thickness is the minimum thickness when the receiving - end core does not exhibit magnetic saturation.

[0039] The beneficial effects of the present invention are as follows:

[0040] The present invention proposes a design method for the receiving - end configuration in an electric - vehicle dynamic wireless power supply system. This method combines the advantages of traditional analytical design methods and finite - element design methods, is applicable to dynamic wireless power - transfer magnetic - coupling mechanisms with complex core structures, and solves the problem of narrow applicability in traditional analytical design methods. At the same time, it can provide theoretical guidance for the design of receiving - end structural parameters, such as the length of the receiving coil, the width of the receiving coil, the connection method of multiple receiving coils, the center - to - center distance of multiple receiving coils, and the size of the receiving - end core. The entire design process only requires a few simulations, solving the problems of narrow applicability in traditional analytical design methods and slow design cycles in traditional finite - element simulation design methods. Meanwhile, it provides theoretical design guidance for the selection of main structural parameters during the structural design of the receiving end. Brief Description of the Drawings

[0041] Figure 1 is a schematic diagram of the electric - vehicle dynamic wireless power supply system described in the present invention;

[0042] Figure 2 is the equivalent circuit diagram of the electric - vehicle dynamic wireless power supply system described in the present invention;

[0043] Figure 3 is a block - diagram of the design method for the receiving - end configuration in an electric - vehicle dynamic wireless power supply system described in the present invention;

[0044] Figure 4 is the design method of the center - to - center distance of multiple receiving coils when maximizing the output power (d c = τ);

[0045] Figure 5 is the arrangement method of the center - to - center distance of multiple receiving coils when the installation space of the vehicle chassis is limited (d c = l coil );

[0046] Figure 6 is a schematic diagram of the structure of a bipolar - type transmitting rail;

[0047] Figure 7 is a simulation result diagram of the distribution of the vertical component Bz of the magnetic field generated by the bipolar - type transmitting rail when energized on the receiving - end plane at x = 0. Detailed Embodiments

[0048] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Specific Embodiment 1

[0050] As Figure 1 - Figure 2 shown, the dynamic wireless power supply system for electric vehicles adopts a "one-to-many" working mode, that is, a single transmitter needs to transmit energy to the receivers of multiple vehicles driving above the road surface simultaneously. Different vehicle models, such as electric vehicles and electric buses, have different requirements for output power, output voltage, and transmission distance. In order to ensure that all vehicles can be charged normally above the transmitting guide rail, it is necessary to independently design the receiver according to the technical indicators of different vehicles.

[0051] In order to solve the problems in the existing dynamic wireless power supply system for electric vehicles, such as the long design cycle, large simulation workload, lack of systematic design ideas and theoretical design guidance caused by the over-reliance on finite element simulation in the receiver configuration design, the present invention proposes a design method for the receiver configuration in a dynamic wireless power supply system for electric vehicles. As Figure 3 shown, the method specifically includes four parts: determination of design indicators and limiting conditions, calculation of electrical parameters, design of structural parameters, and performance verification;

[0052] The determination of the design indicators and limiting conditions specifically includes two steps: the first step is to calculate design indicators such as output power, output voltage, and transmission efficiency according to the battery and chassis height parameters of the electric vehicle; the second step is to determine the limiting conditions in the design process based on the chassis installation space and side shift requirements, such as the maximum coil size, etc., to provide constraints for the subsequent design of the electrical and structural parameters of the receiver;

[0053] The calculation of the electrical parameters specifically includes three steps: the first step is to calculate the equivalent resistance R e and the receiving coil current I S according to design indicators such as output power and output voltage; the second step is to determine the maximum internal resistance r s-max allowed for the receiving coil according to the transmission efficiency design indicator; the third step is to calculate the open-circuit voltage U oc-need required for the receiving coil and the required mutual inductance M need ; the function of the second part (calculation of electrical parameters) is to complete the calculation of electrical parameters such as receiving coil current, induced voltage, and required mutual inductance according to the design indicators, and provide guidance for the receiver structure design in the third part;

[0054] Calculate the equivalent resistance R from Equation (1) and Equation (2) eand the receiving coil current I S ; determine the maximum internal resistance r allowed for the receiving coil according to Equation (3) s-max ; calculate the required open-circuit voltage U and the required mutual inductance M of the receiving coil according to Equation (4) and Equation (5) oc-need need ;

[0055] The expressions of Equation (1) to Equation (5) are as follows:

[0056] R e =(8 / π 2 )·R L =(8 / π 2 )·(U o / I o ) (1)

[0057] Among them, R L is the equivalent load of the battery; R e is the load resistance R L after the equivalent impedance of the uncontrolled rectified current; U o is the charging voltage of the battery; I o is the charging current of the battery;

[0058]

[0059]

[0060] Among them, η is the transmission efficiency index of the receiving end;

[0061]

[0062]

[0063] Among them, I p is the effective value of the current in the transmitting coil.

[0064] The function of the third part (structural parameter design) described above is to take the calculation results of electrical parameters as input conditions, take the limiting conditions as constraints, and complete the design of the structural parameters of the receiving end (such as the size and number of turns of the receiving coil) based on the structural parameter design criteria. The specific structural parameter design includes four steps: The first step is to obtain the magnetic field distribution of the power supply guide rail on the receiving end plane through a single finite element simulation to obtain the magnetic flux density amplitude B z-max ​and the shape parameter σ to provide a reference for subsequent mutual inductance calculation and coil width design; in the second step, with the chassis size and offset performance limit conditions as constraints, the design of the coil length, coil width, coil connection method, and coil center distance is completed in sequence according to the structural parameter design criteria; in the third step, the receiving core size is selected based on the coil size, and the mutual inductance of a single-turn receiving coil is calculated; in the fourth step, the wire diameter is determined from the calculated received current, and the number of turns of the receiving coil is designed according to the required mutual inductance; thus, the preliminary design of the receiving end structure is completed, and the design results can meet the requirements of the system for design indicators and limit conditions such as output power, lateral displacement performance, and chassis size;

[0065] The performance verification specifically includes two steps: in the first step, based on the preliminary design results, a simulation model is built for single simulation to complete the magnetic saturation verification; in the second step, the receiving end efficiency verification is carried out. If the design indicators are met, the design is completed; otherwise, return to the structural parameter design part to re-adjust the structural parameters. The receiving end efficiency verification is carried out by Equation (6), and the expression of Equation (6) is as follows:

[0066]

[0067] where, I s is the effective value of the current in the receiving coil; r s is the calculated internal resistance of the receiving coil after the design is completed.

[0068] The structural parameter design criteria include the receiving coil length design criteria, the receiving coil width design criteria, the multiple receiving coil connection method design criteria, the multiple receiving coil center distance design criteria, and the receiving core design criteria.

[0069] The specific receiving coil length design criteria are as follows:

[0070] During the receiving end design process, the receiving coil length l coil should satisfy:

[0071] 0.75τ ≤ l coil ≤ τ (7)

[0072] where, τ is 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; within the recommended range, the specific value of the receiving coil length l coil is determined by the weights of the output power and the power per unit length; when the weight requirement for the power density is high, the coil length should be reduced, and the value of the receiving coil length l coil should be close to 0.75τ; when the weight requirement for the output power is high, the coil length should be increased, and the value of the receiving coil length l coil should be close to τ.

[0073] The design criterion for the width of the receiving coil is specifically as follows:

[0074] During the design process of the receiving end, the width w of the receiving coil coil should satisfy:

[0075] 2.8σ ≤ w coil ≤ 6σ (8)

[0076] where σ is the shape function of the transmitting magnetic field. The magnetic field generated by the transmitting coil on the receiving end plane is distributed in a Gaussian function along the lateral displacement direction, and the shape function of the Gaussian function is σ.

[0077] Within the recommended range, the specific value of the width w of the receiving coil coil is determined by the weight of the output power and the power per unit width. As the width w of the receiving coil coil increases, the self-inductance and internal resistance of the receiving coil also increase, resulting in an increase in the system voltage stress and a decrease in efficiency. Therefore, in practical applications, in order to balance the output power, the power per unit width, and the system efficiency, the coil width w coil is usually selected as 4σ.

[0078] The design criterion for the connection method of multiple receiving coils is specifically as follows:

[0079] (i) When -0.5τ + 2kτ ≤ d c ≤ 0.5τ + 2kτ, where k is a natural number and d c is the center distance between two adjacent receiving coils. In order to maximize the output power of the receiving coil, the winding directions of two adjacent receiving coils should be the same, that is, the adjacent receiving coils are connected in series forward;

[0080] (ii) When 0.5τ + 2kτ < d c ≤ 1.5τ + 2kτ, in order to maximize the output power of the receiving coil, the winding directions of two adjacent coils should be opposite, that is, the adjacent receiving coils are connected in series in reverse.

[0081] The design criterion for the center distance of multiple receiving coils is specifically as follows:

[0082] As Figure 4 shown, during the design process of the receiving end with a multi-coil structure, the center distances of multiple receiving coils are set to d c = τ to maximize the output power; as Figure 5 shown, when the installation space on the vehicle chassis is limited, the center distances of multiple receiving coils satisfy d c = l coil to reduce the total length at the cost of sacrificing the output voltage moderately to meet the installation space requirements.

[0083] The design criterion for the magnetic core of the receiving end is specifically as follows:

[0084] The receiving core uses a flat core made of soft magnetic ferrite material, and the core length l core satisfies: l receiver ≤l core ≤1.3l receiver , where l receiver is the total length of multiple receiving coils; the core width w core satisfies: w coil ≤w core ≤1.1w coil , and the core thickness is the minimum thickness when the receiving core does not exhibit magnetic saturation.

[0085] The present invention proposes a design method for the receiving end configuration in an electric vehicle dynamic wireless power supply system. This method combines the advantages of traditional analytical design methods and finite element design methods, is applicable to dynamic wireless power magnetic coupling mechanisms with complex core structures, and solves the problem of narrow applicability in traditional analytical design methods. At the same time, it can provide theoretical guidance for the design of receiving end structural parameters, and only requires a few simulations throughout the design process, solving the problems of long design time and unclear design ideas in traditional finite element simulation design methods. Specific Embodiment 2

[0087] To specifically illustrate the application of the design method proposed by the present invention in receiving end design, taking a bipolar type transmitting rail as an example, the present invention gives a receiving end design example with a power rating of 30 kW. In the design example, the structural schematic diagram of the bipolar type transmitting rail is as shown in the appendix Figure 6 shown, and the structural parameters are shown in Table 1. The system adopts the common series - series (SS) compensation method, and the receiving end adopts an uncontrolled rectifier circuit.

[0088] Table 1 Structural Parameters of Bipolar Type Transmitting Rail

[0089]

[0090]

[0091] Part 1: Determination of Design Indexes and Limiting Conditions

[0092] The design example takes an electric car with a maximum output power of 30 kW as the application object. The design indexes and limiting conditions of the receiving end are shown in Table 2.

[0093] Table 2 Design Indexes of Receiving End

[0094]

[0095] Part 2: Electrical Parameter Calculation

[0096] After determining the design indicators and constraints, the second part calculates the electrical parameters of the receiving end. As can be seen from Table 2, the charging voltage is 610V and the charging power is 30kW, and the load resistance R can be calculated L is:

[0097] R L = U o / I o = U 2 o / P out = (610V) 2 / 30kW = 12.4Ω (9)

[0098] The system uses an uncontrolled rectifier circuit, so the equivalent resistance R e is:

[0099] R e = (8 / π 2 ) · R L = (8 / π 2 ) · 12.4Ω = 10.05Ω (10)

[0100] At this time, the current I in the receiving coil s is:

[0101]

[0102] Determine the allowable maximum internal resistance r from the receiving end efficiency s-max :

[0103]

[0104] After obtaining the equivalent resistance R e and the maximum internal resistance r s-max the open-circuit voltage U required at the receiving end can be calculated oc-need to satisfy:

[0105]

[0106] Substitute the transmitting current I p and the resonant frequency f to calculate the mutual inductance M required by the system to meet the output power requirements of the receiving end need :

[0107]

[0108] Part Three: Structural Parameter Design

[0109] After completing the electrical parameter calculation, the third part designs the structural parameters of the receiving end. The first step is to establish a simulation model of the power supply rail to obtain the magnetic field distribution results on the receiving end plane. Through finite element simulation, the magnetic field component B on the receiving end plane can be knownz The distribution at x = 0 is shown in the appendix Figure 7 as follows

[0110] From the figure, the magnetic flux density amplitude B z-max = 608.13 μT can be obtained, and the shape parameter σ = 0.17211 m is obtained through the curve fitting function of the numerical analysis software

[0111] Second, according to the required mutual inductance M need to design the structural parameters of the receiving end

[0112] For the length l coil of the receiving coil, according to Equation (7), after comprehensively considering the output power and the power per unit length, the length of the receiving coil is designed to be 500 mm. Substituting l coil = 500 mm into the expression of the length coefficient k l gives

[0113]

[0114] For the width w coil of the receiving coil, in order to meet the requirements of the design index for the side shift performance, according to Equation (8), after comprehensively considering the output power and the power per unit width, the coil width is set to 800 mm. Substituting w coil = 800 mm into the expression of the width coefficient k w gives

[0115]

[0116] Based on the design criterion of the center distance of the receiving coil, after comprehensively considering the output power and the chassis installation space, the receiving end uses a series structure of two receiving coils. The winding directions of the two receiving coils are opposite and they are placed adjacent to each other, that is, d c = l coil = 500 mm. The number of coils q = 2, substituting into the expression of the spacing coefficient k d gives

[0117]

[0118] According to the size of the receiving winding and the chassis size, the length and width of the receiving core are selected to be 1300 mm * 800 mm, taking into account the output performance and the shielding ability. Therefore, according to experience, the core thickness is selected to be 10 mm. From the core length, the core coefficient satisfies k c = 1.906

[0119] At this time, when the receiving coil has 1 turn, the mutual inductance of the magnetic coupling mechanism is

[0120]

[0121] According to the current I of the receiving coil S , the wire diameter of the receiving coil is selected as d = 10 mm. According to the outer dimensions and wire diameter of the receiving coil, the number of turns N of the receiving coil when the mutual inductance requirement is met can be obtained S :

[0122]

[0123] where the turn coefficient k N has the following expression:

[0124]

[0125] where, k l-i , k w-i are respectively the length coefficient and width coefficient of the i-th turn of the receiving coil;

[0126] Part Four: Performance Verification

[0127] After completing the structural design of the receiving end, the last step is the efficiency verification part. Based on the designed receiving end of the magnetic coupling mechanism, the internal resistance of the receiving end can be calculated to be 0.228 Ω. Substituting the calculated internal resistance into Equation (6), the efficiency η of the receiving end is obtained as follows:

[0128]

[0129] It can be seen from the above formula that the designed receiving end meets the requirements for efficiency in the design specifications, and the design is completed. The specific parameters of the designed receiving end are shown in Table 3

[0130] Table 3 Structural parameters of the designed receiving end with a power rating of 30 kW

[0131]

[0132] The above has introduced in detail a design method for the receiving end configuration in a dynamic wireless power supply system for electric vehicles. In this article, specific examples are used to elaborate on the principle and implementation method of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention

Claims

1. A design method for the receiving end configuration in an electric vehicle dynamic wireless power supply system, characterized in that: The method specifically includes four parts: determination of design indicators and limiting conditions, calculation of electrical parameters, design of structural parameters, and performance verification; The determination of the design indicators and limiting conditions specifically includes two steps: First, calculate the design indicators of output power, output voltage, and transmission efficiency according to the battery and chassis height parameters of the electric vehicle; Second, determine the limiting conditions in the design process based on the chassis installation space and side shift requirements, providing constraints for the subsequent design of the electrical and structural parameters of the receiving end; The specific calculation of the electrical parameters includes three steps: First, calculate the equivalent resistance R e and the receiving coil current I S ; Second, determine the maximum internal resistance r s-max allowed for the receiving coil according to the design specifications; Third, calculate the open-circuit voltage U oc-need required for the receiving coil and the required mutual inductance M need ; The design of the structural parameters specifically includes four steps: First, obtain the magnetic field distribution of the power supply rail on the receiving end plane through a single finite element simulation, and obtain the magnetic density amplitude B z-max and the shape parameter σ to provide a reference for subsequent mutual inductance calculation and coil width design; Second, with the chassis size and offset performance limit conditions as constraints, complete the design of the coil length, coil width, coil connection method, and coil center distance in sequence according to the structural parameter design criteria; Third, select the receiving end core size according to the coil size and calculate the mutual inductance when calculating a single-turn receiving coil; Fourth, determine the wire diameter from the calculated receiving current and complete the turn number design of the receiving coil according to the required mutual inductance; thus, the preliminary design of the receiving end structure is completed; The performance verification specifically includes two steps: First, based on the preliminary design results, build a simulation model for a single simulation to complete the magnetic saturation verification; Second, conduct the receiving end efficiency verification. If the design indicators are met, the design is completed; otherwise, return to the structural parameter design part to re-adjust the structural parameters.

2. The method according to claim 1, wherein Calculate the equivalent resistance R from equations (1) and (2). e and the receiving coil current I S ; Determine the maximum internal resistance r allowed for the receiving coil from equation (3). s-max ; Calculate the open-circuit voltage U required for the receiving coil from equations (4) and (5). oc-need and the required mutual inductance M need ; The expressions of formulas (1) to (5) are as follows: R e = (8 / π 2 )·R L = (8 / π 2 )·(U o / I o ) (1) Among them, R L is the equivalent load of the battery; R e is the load resistance R L after the equivalent impedance through the uncontrolled rectifier current; U o is the charging voltage of the battery; I o is the charging current of the battery; Among them, η is the transmission efficiency index of the receiving end; where I p is the effective value of the current in the transmitting coil.

3. The method according to claim 2, wherein The receiving end efficiency is verified by formula (6), and the expression of formula (6) is as follows: Among them, I s is the effective value of the current in the receiving coil; r s is the calculated internal resistance of the receiving coil after the design is completed.

4. The method according to claim 1, wherein The design criteria for the structural parameters include the design criteria for the length of the receiving coil, the design criteria for the width of the receiving coil, the design criteria for the connection method of multiple receiving coils, the design criteria for the center distance of multiple receiving coils, and the design criteria for the receiving end magnetic core.

5. The method according to claim 4, wherein The design criteria for the length of the receiving coil are specifically: During the design process of the receiving end, the length l of the receiving coil coil should satisfy: 0.75τ ≤ l coil ≤ τ (7) The length l of the receiving coil coil The specific value is determined by the weights of the output power and the power per unit length; when the weight requirement for the power density is high, the coil length should be reduced, and the value of the length l of the receiving coil coil should be close to 0.75τ; when the weight requirement for the output power is high, the coil length should be increased, and the value of the length l of the receiving coil coil should be close to τ.

6. The method according to claim 4, characterized in that The design criteria for the width of the receiving coil are specifically: During the design process of the receiving end, the width w of the receiving coil coil should satisfy: 2.8σ ≤ w coil ≤ 6σ (8) The width w of the receiving coil coil The specific value is determined by the output power and the weight of the power per width.

7. The method according to claim 4, characterized in that, The design criteria for the connection method of multiple receiving coils are specifically: (i) When -0.5τ + 2kτ ≤ d c ≤ 0.5τ + 2kτ, where k is a natural number and d c is the center distance between two adjacent receiving coils. To maximize the output power of the receiving coils, the winding directions of two adjacent receiving coils should be the same, i.e., the adjacent receiving coils are connected in series forward; (ii) When 0.5τ + 2kτ < d c ≤ 1.5τ + 2kτ, in order to maximize the output power of the receiving coil, the winding directions of two adjacent coils should be opposite, that is, the adjacent receiving coils are connected in reverse series.

8. The method according to claim 4, wherein The design criteria for the center distance of multiple receiving coils are specifically: In the process of designing the receiving end of a multi-coil structure, the center-to-center distances of multiple receiving coils are made to satisfy d c = τ to maximize the output power; when the installation space on the vehicle chassis is limited, the center-to-center distances of multiple receiving coils satisfy d c = l coil , sacrificing the output voltage appropriately to reduce the total length and meet the installation space requirements.

9. The method according to claim 4, characterized in that, The design criteria for the receiving end magnetic core are specifically: The receiving core uses a flat core made of soft magnetic ferrite material, and the core length l core satisfies: l receiver ≤l core ≤1.3l receiver , where l receiver is the total length of multiple receiving coils; the core width w core satisfies: w coil ≤w core ≤1.1w coil , and the core thickness is the minimum thickness when the receiving core does not exhibit magnetic saturation.

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