Bilateral LCC type bidirectional wireless charging system and coupling mechanism parameter design method thereof

Abstract

The invention relates to the technical field of two-way wireless power transmission, and particularly discloses a bilateral LCC type two-way wireless charging system and a coupling mechanism parameter design method thereof.The method comprises the steps that a circuit structure of the bilateral LCC type two-way wireless charging system is established, and then expressions of system power and efficiency are deduced according to the circuit structure; the method comprises the steps of determining influence parameters which influence the efficiency and power of a system and are related to a coupling mechanism, then sequentially determining influence parameters beta, alpha p / alpha s and Lrp by taking the requirements of the power, efficiency and current stress of the system as targets, and finally calculating values of primary coil self-inductance Lp, secondary coil self-inductance Ls and secondary compensation inductance Lrs based on the determined beta, alpha p / alpha s and Lrp. And parameters required by the magnetic coupling mechanism and meeting the design requirements are obtained. The coupling mechanism designed through simulation verification and system parameters meet the index requirements of the electric vehicle BIPT system.

Description

Technical Field

[0001] The present invention relates to the technical field of bidirectional wireless power transmission, and in particular to a bilateral LCC bidirectional wireless charging system and a coupling mechanism parameter design method thereof. Background Art

[0002] Wireless Power Transfer (WPT) technology refers to a technology that uses a space medium carrier instead of the traditional wire contact method to achieve power transmission between the power supply and the load end. The space medium carrier includes magnetic field, electric field, laser, microwave, ultrasonic wave and other methods. MC-WPT technology uses the magnetic field as the transmission medium. The wireless transmission of electric energy between the primary and secondary sides is achieved by the mutual conversion of high-frequency alternating magnetic field and electric energy. At present, MC-WPT has been successfully applied to many fields such as consumer electronics, biomedicine, electric vehicles, underwater and special places.

[0003] In magnetically coupled resonant wireless power transmission, the coupling mechanism serves as the port for sending and receiving energy. Its performance directly affects the transmission power and transmission efficiency of the entire system and is the core part of the entire MC-WPT.

[0004] At present, there are many papers that have studied the design and parameter optimization of coupling mechanisms. One paper designed a DD structure energy transmission mechanism, which achieved 2.5kW and 35.5cm wireless power transmission. Another paper proposed a BPP structure inductor while ensuring the power transmission level, which reduced the wire usage by 25.17% compared with the DDQP structure inductor.

[0005] A bidirectional wireless power transmission system is a system that can achieve bidirectional transmission of electric energy, and the primary and secondary sides are mostly designed symmetrically. At present, the research on bidirectional wireless power transmission systems mainly focuses on topological structures, system modeling methods, and energy signal synchronization control. The coupling mechanism has not yet been systematically designed according to the system's transmission power level and efficiency requirements. Summary of the invention

[0006] The present invention provides a bilateral LCC type bidirectional wireless charging system and a coupling mechanism parameter design method thereof, and solves the technical problem of how to design a coupling mechanism according to the transmission power level and efficiency requirements of the system.

[0007] In order to solve the above technical problems, the present invention provides a bilateral LCC type bidirectional wireless charging system and a coupling mechanism parameter design method thereof, including:

[0008] Determine a circuit structure of a bilateral LCC type bidirectional wireless charging system, the circuit structure comprising a primary side and a secondary side, the primary side comprising a primary DC power supply, a primary full-bridge inverter, a primary LCC compensation network, and a primary coil connected in sequence, and the secondary side comprising a secondary coil, a secondary LCC compensation network, a secondary full-bridge inverter, and a secondary DC power supply connected in sequence;

[0009] Determine the expressions of system efficiency and system power according to the circuit structure of the system;

[0010] Let α p =α s And set the value of p The other efficiency influencing parameters of β and α are fixed values. The system efficiency and α are determined according to the expression of system efficiency. p , β, α p Defined as the primary coil self-inductance L p With the primary compensation inductor L rp The ratio, α s Defined as the secondary coil self-inductance L s and the secondary compensation inductor L rs The ratio of β is defined as the secondary compensation inductance L rs With the primary compensation inductor L rp ratio;

[0011] Based on the condition of meeting the system efficiency requirements, according to the system efficiency and α p , β determine the value of β and α p The value range of

[0012] Determine the primary compensation inductance L according to the system current stress requirements rp The lower limit of

[0013] According to the expression of system power, determine the system power and the primary compensation inductance L rp , α p The relationship between α and α is based on the condition that the system power requirement is met. p Determine α within the range of p The value of , and according to α p The value of the primary compensation inductor L is determined by rp The upper limit of

[0014] The primary compensation inductor L rp The primary compensation inductance L is determined from the upper and lower limits of rp The value of

[0015] According to the primary compensation inductance L rp The value of and α p , β, α s , determine the primary coil self-inductance L p , Secondary coil self-inductance Ls and the secondary compensation inductor L rs The value of .

[0016] Furthermore, in the expression of system efficiency, the primary-to-secondary excitation voltage ratio T, the coupling coefficient k between the primary and secondary coils, and α p , α s , β, and the primary-secondary side outward phase shift angle δ are efficiency influencing parameters. The primary-secondary side outward phase shift angle δ is defined as the phase angle of the output fundamental voltage of the secondary side full-bridge inverter lagging behind the output fundamental voltage of the primary side full-bridge inverter.

[0017] Furthermore, the system power and the primary compensation inductor L rp , α p The relationship is expressed as:

[0018]

[0019] Among them, U p_1 , U s_1 They are the fundamental components of the original secondary full-bridge output voltage and is the effective value of , P is the desired system power, and ω is the operating angular frequency of the system.

[0020] Furthermore, under the condition of meeting the system efficiency requirement, according to the system efficiency and α p , β determine the value of β and α p The value range of includes:

[0021] Determine the optional range of β and α according to actual needs p The optional range of

[0022] In the optional range of β and α p In the optional range, according to the system efficiency and α p , β to make the system efficiency and α p , β-related efficiency curve;

[0023] Determine the system efficiency and α according to the efficiency curve p , β are inversely proportional;

[0024] Based on the inverse relationship, within the optional range of β, β takes the smaller value or the minimum value in the efficiency curve where the system efficiency is not less than the system efficiency threshold;

[0025] According to the system efficiency and α p , β-related curve, determine the value of β under α p Within the optional range, the system efficiency is not less than the system efficiency threshold α p The range is α p The value range of .

[0026] Furthermore, the system power and the primary compensation inductance L are determined according to the expression of system power. rp , α p The relationship between α and α is based on the condition that the system power requirement is met. p Determine α within the range of p The value of , and according to α p The value of the primary compensation inductor L is determined by rp The upper limit is:

[0027] Determine L according to actual needs rp The optional range of

[0028] Made in different α p Take the value of L p With L rp The relationship curve of

[0029] Make L under the system power level limit p With L rp The relationship curve of

[0030] Comparing different α p Take the value of L p With L rp The relationship curve between L p With L rp The relationship curve of α p Take the value that makes L rp It has the function of meeting the system power limit and is not less than L rp Lower limit, L rp The selected range is not less than the minimum range and does not exceed the minimum value of the restricted range;

[0031] In α p Under the given value, determine the maximum L that meets the system power limit rp The value is L rp upper limit.

[0032] Furthermore, according to the primary compensation inductance L rp The value of and α p , β, α s , determine the primary coil self-inductance L p , Secondary coil self-inductance L s and the secondary compensation inductor L rs The value of is:

[0033] According to α p and L rp , based on α p =L p / L rp The relationship between L p ;

[0034] According to β and L rp , based on β=L rs / L rp The relationship between L rs ;

[0035] According to α s and L rs , based on α s =L s / L rs The relationship between L s .

[0036] Furthermore, the method further comprises the steps of:

[0037] According to the determined primary coil self-inductance L p , Secondary coil self-inductance L s The structural parameters of the primary coil and secondary coil are determined according to the value and actual needs.

[0038] Further, according to the determined primary coil self-inductance L p , Secondary coil self-inductance L s The structural parameters of the primary coil and the secondary coil are determined according to the value of and actual needs, including:

[0039] According to actual needs, the primary coil and the receiving coil are wound with the same number of turns, the same turn spacing and the same specification of wire;

[0040] Determine the outer diameters of the primary coil and the secondary coil according to actual needs and coupling coefficient requirements;

[0041] According to the determined L p , L s The inner diameters of the primary coil and the secondary coil are determined by the outer diameters of the primary coil and the secondary coil;

[0042] If it is not possible to wind a product that satisfies L p , L s The primary coil and secondary coil of the L rp Change L within the upper and lower limits rp and redetermine the value of L p , L s And the inner diameter of the primary coil and the secondary coil, and repeat this cycle until the winding meets L p , L s The primary coil and the secondary coil.

[0043] Furthermore, the expression of system power is:

[0044]

[0045] Among them, Qp is the quality factor of the primary and secondary coils, Q r To compensate the quality factor of the inductor branch;

[0046] Q p , Q r Defined as:

[0047]

[0048] Among them, R p , R s , R rp , R rs They respectively represent the equivalent internal resistance of the primary coil, secondary coil, primary compensation inductor, and secondary compensation inductor.

[0049] The present invention also provides a bilateral LCC type bidirectional wireless charging system, the key of which is that the coupling mechanism of the bilateral LCC type bidirectional wireless charging system is designed using the coupling mechanism parameter design method of the bilateral LCC type bidirectional wireless charging system.

[0050] The bilateral LCC type bidirectional wireless charging system and the coupling mechanism parameter design method provided by the present invention first establish the circuit structure of the bilateral LCC type bidirectional wireless charging system, then derive the expression of system power and efficiency according to the circuit structure, determine the influencing parameters related to the coupling mechanism that affect the system efficiency and power, and then determine the influencing parameters β, α in turn with the goal of meeting the system power and efficiency and current stress requirements. p / α s , L rp , and finally based on the determined β, α p / α s , L rp Calculate the primary coil self-inductance L p , Secondary coil self-inductance L s and the secondary compensation inductor L rs The value of is obtained to obtain the parameters required for the magnetic coupling mechanism that meets the design requirements. The simulation verifies that the designed coupling mechanism and system parameters meet the index requirements of the electric vehicle BIPT system. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 is a flow chart of a coupling mechanism parameter design method for a bilateral LCC type bidirectional wireless charging system provided by an embodiment of the present invention;

[0052] Figure 2 is a circuit structure diagram of a bilateral LCC type bidirectional wireless charging system provided by an embodiment of the present invention;

[0053] Figure 3 The embodiment of the present invention provides Figure 2 Equivalent circuit diagram of

[0054] Figure 4 The system power and α provided by the embodiment of the present invention p ,β relationship diagram;

[0055] Figure 5 The component current stress and L provided in the embodiment of the present invention are rp Relationship graph;

[0056] Figure 6 The system power limit and α provided by the embodiment of the present invention p Select the schematic diagram;

[0057] Figure 7 The system power limit and L provided in the embodiment of the present invention are rp Select the schematic diagram;

[0058] Figure 8 is a comsol simulation result diagram provided by an embodiment of the present invention;

[0059] Fig. 9 is a curve diagram of coupling coefficient variation when the X and Y directions are offset simultaneously provided by an embodiment of the present invention;

[0060] Fig.10 is a curve diagram of coupling coefficient variation during Z offset provided by an embodiment of the present invention;

[0061] Fig.11 It is a simulink simulation result diagram provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0062] The following specifically illustrates the implementation mode of the present invention in conjunction with the accompanying drawings. The embodiments are provided for illustrative purposes only and cannot be understood as limiting the present invention. The accompanying drawings are provided for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0063] The coupling mechanism parameter design method of the bilateral LCC type bidirectional wireless charging system provided by the embodiment of the present invention is as follows: Figure 1 As shown, the steps include:

[0064] S1. Determine a circuit structure of a bilateral LCC bidirectional wireless charging system, wherein the circuit structure includes a primary side and a secondary side, wherein the primary side includes a primary DC power supply, a primary full-bridge inverter, a primary LCC compensation network, and a primary coil connected in sequence, and the secondary side includes a secondary coil, a secondary LCC compensation network, a secondary full-bridge inverter, and a secondary DC power supply connected in sequence;

[0065] S2. Determine the expression of system efficiency and system power according to the circuit structure of the system;

[0066] S3, let α p =α s And set the value of p The other efficiency influencing parameters of β and α are fixed values. The system efficiency and α are determined according to the expression of system efficiency. p , β, α p Defined as the primary coil self-inductance L p With the primary compensation inductor L rp The ratio of β is defined as the secondary compensation inductance L rs With the primary compensation inductor L rp The ratio, α s Defined as the secondary coil self-inductance L s and the secondary compensation inductor L rs ratio;

[0067] S4, based on the system efficiency and α p , β determine the value of β and α p The value range of

[0068] S5. Determine the primary compensation inductance L according to the system current stress requirements rp The lower limit of

[0069] S6. Determine the system power and the primary compensation inductance L according to the expression of system power rp , α p The relationship between α and α is based on the condition that the system power requirement is met. p Determine α within the range of p The value of , and according to α p The value of the primary compensation inductor L is determined by rp The upper limit of

[0070] S7, compensation inductance L on the primary side rp The primary compensation inductance L is determined from the upper and lower limits of rp The value of

[0071] S8, according to the primary compensation inductance L rp The value of and α p , β, α s , determine the primary coil self-inductance L p , Secondary coil self-inductance L s and the secondary compensation inductor L rs The value of

[0072] S9, according to the determined primary coil self-inductance L p , Secondary coil self-inductance L s The structural parameters of the primary coil and secondary coil are determined according to the value and actual needs.

[0073] Under the premise that the scheme can be implemented, the execution order of steps S1 to S8 can be adjusted. In this example, parameter design is performed based on the system performance indicators in Table 1 below.

[0074] Table 1 System performance indicators

[0075]

[0076] (1) Step S1: Determine the system structure

[0077] Taking the application scenario of electric vehicles as an example, the bilateral LCC compensated BIPT (bidirectional electric vehicle wireless charging) system is mainly composed of a coupling mechanism (transmitting coil, receiving coil, magnetic core, magnetic shielding structure), a primary and secondary resonant compensation network (both use LCC compensation networks) and a primary and secondary active bridge (using a full-bridge inverter composed of 4 MOS tubes). The system block diagram is as follows: Figure 2 shown.

[0078] exist Figure 2 In, V dp and V ds They represent the primary DC power supply and the secondary DC power supply respectively. MOS tubes S1, S2, S3, and S4 form a primary full-bridge inverter. MOS tubes T1, T2, T3, and T4 form a secondary full-bridge inverter. The primary compensation inductor L rp , primary side series compensation capacitor C p And the primary side parallel compensation capacitor C fp The primary side LCC compensation network and the secondary side compensation inductor L rp , Secondary side series compensation capacitor C s And the secondary side parallel compensation capacitor C fs The secondary side LCC compensation network is formed, L p and L s They represent the self-inductance of the primary coil and the receiving coil respectively.

[0079] (2) Step S2: System Energy Efficiency Analysis

[0080] Ignoring the system harmonic components, the system's fundamental equivalent circuit is as follows: Figure 3 shown. Figure 3 middle, and They are respectively the fundamental component of the original secondary full-bridge output voltage, R p , R s , R rp , R rs They represent the equivalent internal resistance of the primary coil, secondary coil, primary compensation inductor, and secondary compensation inductor, respectively. Lp ,I Lrp ,I Ls ,I Lrs L p , Lrp , L s , L rs of current.

[0081] and V dp 、V ds Satisfy between:

[0082]

[0083] Among them, δ is the phase angle of the secondary full-bridge output fundamental voltage lagging the primary full-bridge output fundamental voltage.

[0084] Write down the KVL equations of the original and secondary sides respectively, we have:

[0085]

[0086] Where ω is the operating angular frequency of the system.

[0087] When the system is in resonance, we can solve:

[0088]

[0089] According to formula (4), the absolute values ​​of active power P and reactive power Q transmitted by the system can be obtained:

[0090]

[0091] Where Re represents the real part, Im represents the imaginary part, M represents the mutual inductance between the primary and secondary coils, k represents the coupling coefficient between the primary and secondary coils, * represents conjugate, and X p and X s They represent the primary compensation inductance L rp and the secondary compensation inductor L rs The reactance, α p Defined as the primary coil self-inductance L p With the primary compensation inductor L rp The ratio, α s Defined as the secondary coil self-inductance L s and the secondary compensation inductor L rs The ratio is:

[0092]

[0093] The total loss of the system can be expressed as:

[0094]

[0095] Q p is the quality factor of the primary and secondary coils, Q r To compensate the quality factor of the inductor branch, they are defined as:

[0096]

[0097] The transmission efficiency of the system can be approximately calculated as:

[0098]

[0099] Among them, T is the ratio of the primary and secondary excitation voltages, and β is the primary and secondary compensation inductance ratio, that is:

[0100]

[0101] From formula (9), we can see that the transmission efficiency of the system is related to the excitation voltage ratio T, the coupling coefficient k, and the inductance ratio α of the primary and secondary coils’ self-inductance and the compensation inductance. p and α s , the primary-to-secondary side compensation inductance ratio β, and the primary-to-secondary side outward shift phase angle δ.

[0102] (3) Steps S3 and S4: Determine β and α p The value range of

[0103] When designing the parameters of the coupling mechanism, the method of controlling variables is adopted to first determine some parameters and then determine some parameters.

[0104] For the subsequent simulation analysis, this example first determines the outer diameter of the primary and secondary coils. According to actual needs, this example performs an asymmetric design of the primary and secondary coils, and performs a comsol simulation when the number of turns is 8, the turn spacing is the same, and the winding specifications are consistent to determine the outer diameter of the primary and secondary coils that meets the coupling coefficient requirements.

[0105] As shown in Table 2, when the outer diameter of the primary and secondary coils is 700mm-600mm and 600mm-500mm, the coupling coefficient of the primary and secondary coils can meet the requirements (k≥0.2). Among them, the size of the primary and secondary coils with an outer diameter of 600mm-500mm is relatively smaller, so this group is selected as the optimized coil size.

[0106] Table 2 Primary and secondary coil outer diameter and coupling coefficient

[0107]

[0108] From formula (9), when assuming T = 1 and δ = π / 2, the system efficiency formula is as follows:

[0109]

[0110] Based on the above relationship, step S4 specifically includes the following steps:

[0111] S41. Determine the optional range of β and α according to actual needs p The optional range of

[0112] S42, in the optional range of β and α p In the optional range, according to the system efficiency and α p , β to make the system efficiency and α p , β-related efficiency curve;

[0113] S43. Determine the system efficiency and α according to the efficiency curve p , β are inversely proportional;

[0114] S44. Based on the inverse relationship, within the optional range of β, β takes a smaller value or a minimum value in the efficiency curve in which the system efficiency is not less than the system efficiency threshold;

[0115] S45, according to system efficiency and α p , β-related curve, determine the value of β under α p Within the optional range, the system efficiency is not less than the system efficiency threshold α p The range is α p The value range of .

[0116] Here is a specific example.

[0117] S41. According to actual needs, the optional range of β is 1±0.4 (between 0.6 and 1.4) and α p The optional range (between 1 and 8);

[0118] S42, in the optional range of β and α p In the optional range, according to the system efficiency and α p , β to make the system efficiency and α p , β (β takes discrete values ​​of 0.6, 0.8, 1, 1.2, 1.4, α p Take the efficiency curve related to discrete values ​​1, 2, 3, 4, 5, 6, 7, 8) (k is 0.2, a s =a p , Q r With Q p Take 600), such as Figure 4 As shown (beta is β);

[0119] S43. Determine the system efficiency and α according to the efficiency curve p , β are inversely proportional, so we can know that in the system parameter design, α p and β should be as small as possible to improve system efficiency;

[0120] S44. Based on the inverse relationship, within the optional range of β, β is taken as the smaller value or the minimum value in the efficiency curve where the system efficiency is not less than the system efficiency threshold (the requirement for the system output efficiency is ≥95%, and in order to maintain a certain margin, the system efficiency threshold is set to 98%). In this example, β is taken as 5 / 6;

[0121] S45, according to system efficiency and α p , β-related curve, determine that when β takes 5 / 6 of the value, under α p Within the optional range, the system efficiency is not less than the system efficiency threshold of 98% α p The range (1 to 5) is α p The value range of .

[0122] (4) Step S5: Determine the primary compensation inductance L rp The lower limit

[0123] When β, α p / α s , when it is determined, we only need to determine the primary compensation inductance L rp , primary coil self-inductance L p , Secondary coil self-inductance L s and the secondary compensation inductor L r Any parameter in can be used to obtain other parameters of the coupling mechanism. In this example, we first determine the parameter L rp Take this as an example to illustrate.

[0124] The designed BIPT system needs to consider the limitation of system efficiency and the limitation of component current stress. In practice, the current stress of components needs to be considered, where the series resonant inductor current I Lrp and I Lrs Need to be less than 60A, coil current I Lp and I Ls It needs to be less than 63.64A. According to formula (4), the current stress can be calculated with respect to L rp The curve diagram is as follows Figure 5 As shown (I Lp and I Ls overlap). Figure 5 As you can see, L rp The value needs to be greater than 18uH to meet the requirements, and L rp The lower limit is 18uH.

[0125] (5) Step S6: Determine α p And the primary compensation inductor L rp Upper limit

[0126] The design step S6 in this example specifically includes the following steps:

[0127] S61. Determine L according to actual needsrp The optional range of

[0128] S62, make p Take the value of L p With L rp The relationship curve of

[0129] S63, make L under the system power level limit p With L rp The relationship curve of

[0130] S64. Comparison of different α p Take the value of L p With L rp The relationship curve between L p With L rp The relationship curve of α p Take the value that makes L rp It has the function of meeting the system power limit and is not less than L rp Lower limit, L rp The selected range is not less than the minimum range and does not exceed the minimum value of the restricted range;

[0131] S65, in α p Under the value, determine the L that meets the system power limit rp upper limit.

[0132] Based on the above analysis, the output power of the system can be calculated by the following formula:

[0133]

[0134] Take a s =a p , β takes the ratio of the outer diameter of the original and secondary coils as 5 / 6, and further simplification yields:

[0135]

[0136] The following is a method to determine the primary compensation inductance L rp A specific example of the upper limit includes the steps of:

[0137] S61. Determine L according to actual needs rp The optional range is from 9uH to 27uH;

[0138] S62, make p Value (α p Take discrete values ​​1, 2, 3, 4, 5) L p With L rp The relationship curve, such as Figure 6 As shown;

[0139] S63, make L under the system power level limit p With L rp The relationship curve, such as Figure 6 As shown;

[0140] S64. Comparison of different α p Take the value of L p With L rp The relationship curve between L p With L rp The relationship curve of α p Take the value that makes L rp It has the function of meeting the system power limit (on the system power limit curve) and being not less than L rp Lower limit (18uH), L rp The selection range is not less than the minimum range (4uH) and does not exceed the minimum value of the limit range (27-18=9uH);

[0141] S65, in α p Under the value, determine the L that meets the system power limit rp The value of L rp upper limit.

[0142] In step S64, the L at the upper left side of the red curve p With L rp The selected values ​​all meet the requirements, the first curve α p =1 is always below the power limit curve, which does not meet the requirements. The second curve α p =2 The selection range is narrower, the third curve α p =3 The selection range is moderate, the fourth curve α p =4 The selection range is wider, the fifth curve α p =5 has the widest selection range, but L p With L rp If the gap is too large, the coil current stress will be too large and exceed the limit range. p The value is 4.

[0143] In α p When the value is 4, the maximum L that meets the system power limit rp Value (22uH) is L rp upper limit.

[0144] (6) Step S7: Determine the primary compensation inductance L rp Value

[0145] The primary compensation inductor L rp The initial selection parameter is the series resonant inductor L, with the upper and lower limits of 18uH and 22uH. rp is 21uH, such as Figure 7 As shown, at this time L p It is 8.4uH.

[0146] (7) Step S8: Determine L p , L s and L rs

[0147] Step S8 specifically includes the following steps:

[0148] S81, according to α p and L rp , based on α p =L p / L rp The relationship between L p ;

[0149] S82, according to β and L rp , based on β=L rs / L rp The relationship between L rs ;

[0150] S83, according to α s and L rs , based on α s =L s / L rs The relationship between L s .

[0151] According to the determined L p , L s , L rs , L rp The value of the compensation capacitor can be determined by the system resonance relationship. Finally, the coupling mechanism of the system and its compensation network parameters are shown in Table 3.

[0152] Table 3

[0153]

[0154] (8) Step S9: Determine the inner diameter of the primary and secondary coils and wind the coils

[0155] The step S9 specifically includes the following steps:

[0156] S91. Determine, according to actual requirements, that the primary coil and the receiving coil are wound with the same number of turns, the same turn spacing, and the same specification of wire (as described above);

[0157] S92. Determine the outer diameters of the primary coil and the secondary coil according to actual needs and coupling coefficient requirements (as described above);

[0158] S93, according to the determined L p , L sThe inner diameters of the primary and secondary coils are determined by their outer diameters. The inner diameters of the primary and secondary coils are 350mm and 290mm respectively.

[0159] S94, if it is not possible to wind a product that satisfies L p , L s The primary coil and secondary coil of L rp Change L within the upper and lower limits rp and re-determine the value of L p , L s And the inner diameter of the primary coil and the secondary coil, and repeat this cycle until the winding meets L p , L s The primary coil and the secondary coil.

[0160] This example also protects a bilateral LCC type bidirectional wireless charging system obtained by adopting the above-mentioned design method.

[0161] In summary, the bilateral LCC type bidirectional wireless charging system and the coupling mechanism parameter design method provided by the embodiment of the present invention first establish the circuit structure of the bilateral LCC type bidirectional wireless charging system, and then derive the expression of system power and efficiency according to the circuit structure, determine the influencing parameters related to the coupling mechanism that affect the system efficiency and power, and then determine the influencing parameters β, α in turn with the goal of meeting the system power and efficiency and current stress requirements. p / α s , L rp , and finally based on the determined β, α p / α s , L rp Calculate the primary coil self-inductance L p , Secondary coil self-inductance L s and the secondary compensation inductor L rs The value of is used to obtain the parameters required for the magnetic coupling mechanism that meets the design requirements.

[0162] The following is an experimental verification.

[0163] (1) Self-sensing verification

[0164] According to the inductance values ​​of the primary and secondary coils designed above, the design parameters and dimensions of the coupling mechanism coil are shown in Table 4.

[0165] Table 4 Designed coupling mechanism coil size parameters

[0166]

[0167] The relevant simulation is carried out in Comsol, and the inductance and coupling coefficient of the primary and secondary coils are obtained as follows Figure 8 As shown. Figure 8It can be seen that the self-inductance between the primary and secondary coils basically meets the design value, the output power of the secondary side meets the power transmission requirements (≥30kW), the system efficiency of 99.45% (31391 / 31564) meets the efficiency requirements (≥95%), and the coupling coefficient between the primary and secondary coils meets the coupling coefficient requirements (k≥0.2). The simulation verifies that the designed coupling mechanism and system parameters meet the index requirements of the electric vehicle BIPT system.

[0168] (2) Anti-drift verification

[0169] The anti-deviation performance of the coupling mechanism is verified by simultaneously deviating in the X and Y directions (length and width directions of the primary coil) and by deviating in the Z direction (height direction). The coupling coefficient variation curve when the X and Y directions are deviated simultaneously is shown in the figure. Fig. 9 As shown, the coupling coefficient variation curve when the Z direction is offset is as follows Fig.10 As shown. Fig. 9 It can be seen that within the X, Y offset range of 30mm, the coupling coefficient remains above 0.2, within the X, Y offset range of 60mm, the coupling coefficient remains above 0.18, and within the X, Y offset range of 100mm, the coupling coefficient remains above 0.15. Fig.10 It can be seen that within the Z offset range of 5mm, the coupling coefficient remains above 0.2, within the Z offset range of 20mm, the coupling coefficient remains above 0.18, and within the X, Y offset range of 45mm, the coupling coefficient remains above 0.15. Fig. 9 and Fig.10 It can be seen that the designed coupling mechanism has good anti-deviation performance.

[0170] (3) Simulink simulation

[0171] The system power and system efficiency simulated by simulink are as follows Fig.11 As shown, the output power of the designed system is 31.2kW and the system efficiency is 96.46%, which meets the system demand indicators.

[0172] The above simulation verifies that the designed coupling mechanism and system parameters meet the index requirements of the electric vehicle BIPT system.

[0173] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A coupling mechanism parameter design method for a bilateral LCC type bidirectional wireless charging system, characterized in that: include: Determine a circuit structure of a bilateral LCC type bidirectional wireless charging system, the circuit structure comprising a primary side and a secondary side, the primary side comprising a primary DC power supply, a primary full-bridge inverter, a primary LCC compensation network, and a primary coil connected in sequence, and the secondary side comprising a secondary coil, a secondary LCC compensation network, a secondary full-bridge inverter, and a secondary DC power supply connected in sequence; Determine the expressions of system efficiency and system power according to the circuit structure of the system; Let α p =α s And set the value of p The other efficiency influencing parameters of β and α are fixed values. The system efficiency and α are determined according to the expression of system efficiency. p , β, α p Defined as the primary coil self-inductance L p With the primary compensation inductor L rp The ratio, α s Defined as the secondary coil self-inductance L s and the secondary compensation inductor L rs The ratio of β is defined as the secondary compensation inductance L rs With the primary compensation inductor L rp ratio; Based on the condition of meeting the system efficiency requirements, according to the system efficiency and α p , β determine the value of β and α p The value range of Determine the primary compensation inductance L according to the system current stress requirements rp The lower limit of According to the expression of system power, determine the system power and the primary compensation inductance L rp , α p The relationship between α and α is based on the condition that the system power requirement is met. p Determine α within the range of p The value of , and according to α p The value of the primary compensation inductor L rp The upper limit of The primary compensation inductor L rp The primary compensation inductance L is determined from the upper and lower limits of rp The value of According to the primary compensation inductance L rp The value of and α p , β, α s , determine the primary coil self-inductance L p , Secondary coil self-inductance L s and the secondary compensation inductor L rs The value of .

2. The coupling mechanism parameter design method of the bilateral LCC type bidirectional wireless charging system according to claim 1 is characterized in that: In the expression of system efficiency, the primary-to-secondary excitation voltage ratio T, the coupling coefficient k between the primary and secondary coils, and α p , α s , β, and the primary-secondary side outward phase shift angle δ are efficiency influencing parameters. The primary-secondary side outward phase shift angle δ is defined as the phase angle of the output fundamental voltage of the secondary side full-bridge inverter lagging behind the output fundamental voltage of the primary side full-bridge inverter.

3. The coupling mechanism parameter design method of the bilateral LCC type bidirectional wireless charging system according to claim 1 is characterized in that: System power and primary compensation inductance L rp , α p The relationship is expressed as: Among them, U p_1 , U s_1 They are the fundamental components of the original secondary full-bridge output voltage and is the effective value of , P is the desired system power, and ω is the operating angular frequency of the system.

4. The coupling mechanism parameter design method of the bilateral LCC type bidirectional wireless charging system according to claim 1 is characterized in that: Based on the condition of meeting the system efficiency requirements, according to the system efficiency and α p , β determine the value of β and α p The value range of includes: Determine the optional range of β and α according to actual needs p The optional range of In the optional range of β and α p In the optional range, according to the system efficiency and α p , β to make the system efficiency and α p , β-related efficiency curve; Determine the system efficiency and α according to the efficiency curve p , β are inversely proportional; Based on the inverse relationship, within the optional range of β, β takes the smaller value or the minimum value in the efficiency curve where the system efficiency is not less than the system efficiency threshold; According to the system efficiency and α p , β-related curve, determine the value of β under α p Within the optional range, the system efficiency is not less than the system efficiency threshold α p The range is α p The value range of .

5. The coupling mechanism parameter design method of the bilateral LCC type bidirectional wireless charging system according to claim 1 is characterized in that: According to the expression of system power, determine the system power and the primary compensation inductance L rp , α p The relationship between α and α is based on the condition that the system power requirement is met. p Determine α within the range of p The value of , and according to α p The value of the primary compensation inductor L rp The upper limit is: Determine L according to actual needs rp The optional range of Made in different α p Take the value of L p With L rp The relationship curve of Make L under the system power level limit p With L rp The relationship curve of Comparing different α p Take the value of L p With L rp The relationship curve between L p With L rp The relationship curve of α p Take the value that makes L rp It has the function of meeting the system power limit and is not less than L rp Lower limit, L rp The selected range is not less than the minimum range and does not exceed the minimum value of the restricted range; In α p Under the given value, determine the maximum L that meets the system power limit rp The value is L rp upper limit.

6. The coupling mechanism parameter design method of the bilateral LCC type bidirectional wireless charging system according to claim 1 is characterized in that: According to the primary compensation inductance L rp The value of and α p , β, α s , determine the primary coil self-inductance L p , Secondary coil self-inductance L s and the secondary compensation inductor L rs The value of is: According to α p and L rp , based on α p =L p / L rp The relationship between L p ; According to β and L rp , based on β=L rs / L rp The relationship between L rs ; According to α s and L rs , based on α s =L s / L rs The relationship between L s .

7. The coupling mechanism parameter design method of the bilateral LCC type bidirectional wireless charging system according to any one of claims 1 to 6, characterized in that: The method further comprises the steps of: According to the determined primary coil self-inductance L p , Secondary coil self-inductance L s The structural parameters of the primary coil and secondary coil are determined according to the value and actual needs.

8. The coupling mechanism parameter design method of the bilateral LCC type bidirectional wireless charging system according to claim 7, characterized in that: According to the determined primary coil self-inductance L p , Secondary coil self-inductance L s The structural parameters of the primary coil and the secondary coil are determined according to the value of and actual needs, including: According to actual needs, the primary coil and the receiving coil are wound with the same number of turns, the same turn spacing and the same specification of wire; Determine the outer diameters of the primary coil and the secondary coil according to actual needs and coupling coefficient requirements; According to the determined L p , L s The inner diameters of the primary coil and the secondary coil are determined by the outer diameters of the primary coil and the secondary coil; If it is not possible to wind a product that satisfies L p , L s The primary coil and secondary coil of L rp Change L within the upper and lower limits rp and redetermine the value of L p , L s And the inner diameter of the primary coil and the secondary coil, and repeat this cycle until the winding meets L p , L s The primary coil and the secondary coil.

9. The coupling mechanism parameter design method of the bilateral LCC type bidirectional wireless charging system according to any one of claims 2 to 6, characterized in that: The expression of system power is: Among them, Q p is the quality factor of the primary and secondary coils, Q r To compensate the quality factor of the inductor branch; Q p , Q r Defined as: Among them, R p , R s , R rp , R rs They respectively represent the equivalent internal resistance of the primary coil, secondary coil, primary compensation inductor, and secondary compensation inductor.

10. Bilateral LCC type bidirectional wireless charging system, characterized by: The coupling mechanism of the bilateral LCC type bidirectional wireless charging system is designed by using the coupling mechanism parameter design method of the bilateral LCC type bidirectional wireless charging system according to any one of claims 1 to 9.

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