Wireless charging system for electric vehicles compatible with 11kW and 22kW receivers

Abstract

This invention relates to the field of wireless power transmission technology, specifically disclosing a wireless charging system for electric vehicles adapted to 11kW and 22kW receivers. Based on an LCC-S topology, it effectively reduces the number of on-board components and the weight of on-board equipment, meeting the lightweight requirements of electric vehicle on-board units. Under the national standard-given transmitter size parameters, interoperable electrical parameters are designed for two different power levels, 11kW and 22kW, solving the drawback of one transmitter corresponding to one receiver in wireless charging of electric vehicles. The invention provides the parameter selection range for the transmitter compensation inductance and system coupling coefficient for the two high-power levels of 11kW and 22kW, under the conditions of high efficiency and reduced electrical stress on components, and thus designs a wireless charging system adapted to a unified transmitter, meeting the development needs of wireless electric vehicles.

Description

Technical Field

[0001] This invention relates to the field of wireless power transmission technology, and more particularly to a wireless charging system for electric vehicles that is compatible with 11kW and 22kW receivers. Background Technology

[0002] The rapid development of wireless power transfer technology has brought new solutions to electric vehicle (EV) charging. It offers advantages such as ease of use, speed, safety, reliability, high energy storage capacity, and the ability to automate charging, effectively addressing the inherent shortcomings of wired EV charging. Currently, EVs are undergoing detailed research in areas such as electromagnetic shielding, bioelectromagnetic safety, simultaneous energy and signal transmission, dynamic wireless charging, and foreign object detection. However, research progress on the interoperability of EV wireless charging is relatively limited. While international standards for EV wireless charging have largely met industry needs, compatibility between different power levels remains poor, making interoperability a critical issue that urgently needs to be addressed for the industry's development. Currently, commonly used power levels are 3.7kW, 7.7kW, and 11kW, corresponding to wireless charging systems WPT1, WPT2, and WPT3, respectively. With the increasing demand for high-power wireless charging in EVs, a receiver power level of 22kW is defined as WPT4. Regarding the receiver's ground clearance range, it is mainly divided into three categories: 100–150mm, 140–210mm, and 170–250mm. Currently, there is a lack of interoperability designs for the 11kW and 22kW high-power classes. Summary of the Invention

[0003] This invention provides a wireless charging system for electric vehicles that is compatible with 11kW and 22kW receivers. The technical problem it solves is: how to design a wireless charging system for electric vehicles that can be compatible with 11kW and 22kW receivers.

[0004] To solve the above technical problems, the present invention provides a wireless charging system for electric vehicles that is compatible with 11kW and 22kW receivers, including a transmitter and a receiver, wherein the receiver is an 11kW receiver or a 22kW receiver.

[0005] The parameters of the wireless charging system for electric vehicles are determined using the following steps:

[0006] S1. Based on the constant voltage output requirement and the lightweight requirement of the electric vehicle on-board unit, the electric vehicle wireless charging system adopts the LCC-S type circuit topology.

[0007] S2. Based on the applicable vehicle models of the 11kW and 22kW receivers, determine the ground clearance of the 11kW and 22kW receivers, as well as the on-board battery charging voltage and the resonant operating angular frequency ω of the input DC voltage.

[0008] S3. Based on the design standards for wireless charging systems for electric vehicles, determine the structural parameters of the transmitter, the scanning range of the coupling coefficient k applicable to all power levels in the design standards, and the compensation inductance L of the transmitter. f The scanning range;

[0009] S4. Determine the lower limit of system transmission efficiency η min And in satisfying η min Under the given conditions, within the parameter range determined in step S3, the compensation inductor L is determined. f The selectable range and the range of values ​​for the coupling coefficient k;

[0010] S5. Under the electrical parameter stress constraints at the transmitting and receiving ends, the compensation inductance L determined in step S4... f From the selectable range, determine the compensation inductance L. f The range of values ​​for;

[0011] S6, in the compensation inductor L f Determine L within the range of values. f The specific value is determined based on the resonance relationship, which sets the parameter value of the transmitter compensation capacitor.

[0012] S7. Within the range of the coupling coefficient k, and in accordance with the design standards, determine the structural parameters of the coils for the 11kW and 22kW receivers and the parameter values ​​of the compensation capacitors for the receivers.

[0013] Furthermore, step S5 specifically includes the following steps:

[0014] S51. Within the parameter range determined in step S3, simulate and obtain the transmitter current I at power levels of 11kW and 22kW. p Receiver current I s With compensation inductor L f The relationship curve between the coupling coefficient k and the coupling coefficient k;

[0015] S52. Determine the maximum allowable effective current value of the receiving coil according to the design standard, and determine the compensation inductor L under the constraint of the maximum allowable effective current value, based on the relationship curve obtained in step S51. f The selection range;

[0016] S53. Within the parameter range determined in step S3, simulate and obtain the voltage U of the two compensation capacitors at the transmitter for power levels of 11kW and 22kW. Cp U Cf With compensation inductor L f The relationship curve between the coupling coefficient k and the coupling coefficient k;

[0017] S54. Determine the maximum voltage of the two compensation capacitors at the transmitting end, and under the constraint of the maximum voltage, determine the compensation inductance L according to the relationship curve obtained in step S53. f The selection range;

[0018] S55, the compensation inductor L determined in steps S52 and S54. f The selected range and the parameter range determined in step S4 are combined to obtain the compensation inductor L. f The range of values ​​for .

[0019] Further, in step S7, the structural parameters of the coil at the 11kW receiver are determined, specifically including the following steps:

[0020] S71. Determine the outer dimensions, side length, and wire diameter of the 11kW receiving coil according to the design standards.

[0021] S72. Simulate and obtain the coupling coefficients corresponding to different coil turns under the outer dimension side length and wire diameter determined in step S71, and filter to obtain the coupling coefficients that satisfy the value range of the coupling coefficient k.

[0022] S73. Determine a specific coupling coefficient value based on the coupling coefficients filtered in step S72, and calculate the corresponding coil self-inductance based on the coupling coefficient value.

[0023] S74. Simulation yields the number of coil turns that satisfy the coil's self-inductance.

[0024] Furthermore, in step S7, the step of determining the structural parameters of the coil of the 22kW receiver is the same as in steps S71 to S74.

[0025] Furthermore, step S4 specifically includes the following steps:

[0026] S41. Determine the minimum transmission efficiency η for systems adapted to 11kW and 22kW power levels. min ;

[0027] S42, Simulation to obtain the compensation inductance L f The scanning range of the coupling coefficient k, and the transmission efficiency of the system at power levels of 11kW and 22kW;

[0028] S43. Determine that the transmission efficiency of the system at both 11kW and 22kW power levels is greater than or equal to η. min Compensating inductor L f The range of the compensation inductance L and the range of the coupling coefficient k are given by the range of the compensation inductance L. f The selectable range and the range of values ​​for the coupling coefficient k.

[0029] Furthermore, the step S7 is followed by the following step:

[0030] S8. Perform simulation based on the determined system parameters to obtain the system output and determine whether the output requirements are met. If not, return to step S6 to adjust the parameters.

[0031] Furthermore, in steps S6 and S7, the parameter values ​​of the transmitting end compensation capacitor and the receiving end compensation capacitor are determined according to the following formula:

[0032]

[0033] Among them, C f Indicates the connection with the transmitting coil L p Parallel compensation capacitors, C p Indicates the connection with the transmitting coil L p Series-connected compensation capacitor, L s Indicates the receiving coil, C s Indicates the connection with the receiving coil L s Compensating capacitors connected in series.

[0034] Furthermore, the compensation inductor L f Split into two L values ​​with equal sensitivity f1 and L f2 They are connected in series with the two output terminals of the high-frequency inverter circuit at the transmitting end and the compensation capacitor C, respectively. f between.

[0035] This invention provides a wireless charging system for electric vehicles compatible with 11kW and 22kW receivers. Based on an LCC-S topology, it effectively reduces the number of on-board components and the weight of on-board equipment, meeting the lightweight requirements of electric vehicle on-board units. Under the national standard-given transmitter size parameters, it designs interoperable electrical parameters for two different power levels, 11kW and 22kW, addressing the drawback of one transmitter corresponding to one receiver in electric vehicle wireless charging. It provides the parameter selection range for transmitter compensation inductance and system coupling coefficient for both 11kW and 22kW high-power levels, ensuring high efficiency and reducing electrical stress on components. This allows for the design of a wireless charging system compatible with a unified transmitter, meeting the development needs of wireless electric vehicles. Attached Figure Description

[0036] Figure 1 This is a circuit topology diagram of an electric vehicle wireless charging system adapted to 11kW and 22kW receivers provided in an embodiment of the present invention.

[0037] Figure 2 This is a structural diagram of the transmitting coil provided in an embodiment of the present invention;

[0038] Figure 3 The transmitting end compensation inductor L provided in this embodiment of the invention fAnd simulation results of coupling coefficient k versus transmission efficiency;

[0039] Figure 4 The transmitting current I provided in this embodiment of the invention p and the current I at the receiving end s In both 11kW and 22kW power modes, with compensation inductor L f The relationship curve between the coupling coefficient k and the coupling coefficient k;

[0040] Figure 5 The transmitter compensation capacitor voltage U provided in this embodiment of the invention is for two power levels, 11kW and 22kW. Cp and U Cf With compensation inductor L f The relationship curve between the coupling coefficient k and the coupling coefficient k;

[0041] Figure 6 These are load voltage output curves of the 11kW and 22kW devices provided in the embodiments of the present invention;

[0042] Figure 7 This is a load current output curve diagram of the 11kW and 22kW devices provided in the embodiments of the present invention. Detailed Implementation

[0043] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. The embodiments are given for illustrative purposes only and should not be construed as limiting the present invention. The accompanying drawings are 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.

[0044] The electric vehicle wireless charging system adapted to 11kW and 22kW receivers provided in this embodiment of the invention, such as... Figure 1 As shown, it includes a transmitter and a receiver, with the receiver being either an 11kW or 22kW receiver. Since both the 11kW and 22kW receivers use the same circuit structure... Figure 1 The receiver shown represents both an 11kW receiver and a 22kW receiver. Figure 1 Middle,U dc This is the system's DC input voltage. MOS switches Q1-Q4 form a voltage-source full-bridge inverter. This invention will compensate for the inductor L... f Split into two L values ​​with equal sensitivity f1 and L f2 To eliminate common-mode interference, C f C p These are the compensation capacitors for the transmitter resonant network, C s L is the compensation capacitor for the receiver resonant network. p and L sThese are the self-inductances of the transmitting and receiving coils, respectively; M is the mutual inductance between the transmitting and receiving coils; and I is the self-inductance between the transmitting and receiving coils. p and I s These are the transmitting coil current and the receiving coil current, respectively, R eq It is the equivalent load, R L For output load, R p R is the internal resistance of the transmitting coil. Lf R is the internal resistance of the transmitter inductor. s To determine the internal resistance of the receiving coil, four diodes D1-D4 form a rectifier circuit, U L This represents the voltage across the load.

[0045] Among them, U dc The AC effective value U is obtained after high-frequency inversion. in It can be approximated as:

[0046]

[0047] Considering the system receiver includes a rectifier bridge circuit, the equivalent resistance R before the rectifier bridge at the receiver is... eq for:

[0048]

[0049] To ensure the system operates in a resonant state, the circuit compensation parameters should satisfy:

[0050]

[0051] w is the resonant angular frequency of the input DC voltage.

[0052] When the system resonates, the receiver impedance Z s It can be represented as:

[0053] Z s =R s +R eq (4)

[0054] Transmitter reflection impedance Z ref It can be represented as:

[0055]

[0056] Ignoring the internal resistance of the power supply, the impedance of the transmitter can be expressed as:

[0057]

[0058] To analyze the losses of the coil and inductor, the quality factor Q of the transmitting coil is... p Receiver coil quality factor Q s and the quality factor Q of the transmitter inductorLf If the value is 300, then the impedance R of the transmitting coil is... p、 Receiver coil impedance R s and the inductance R of the transmitting end Ls They are respectively:

[0059]

[0060] The currents in the transmitting coil and the receiving coil are:

[0061]

[0062] Transmitter compensation capacitor voltage U Cp and U Cf They are respectively:

[0063]

[0064] By combining the KCL and KVL equations, the input power P of the LCC-S topology can be obtained. in Output power P out And the transmission efficiency is:

[0065]

[0066] When the ideal output power P out Given that the receiving end inductance L s It can be given by the following formula:

[0067]

[0068] Where k is the coupling coefficient, and its relationship with mutual inductance is:

[0069]

[0070] From equation (10) combined with equations (4), (6), and (12), it can be seen that when the input voltage U dc Output voltage U L Output power rating and transmitter coil inductance L p When determined, the output efficiency is only related to the compensation inductance L. f It is related to the coupling coefficient k.

[0071] Based on the above conclusions, this invention provides a wireless charging system for electric vehicles that is compatible with 11kW and 22kW receivers, the parameters of which are determined by the following steps:

[0072] S1. Based on the constant voltage output requirement and the lightweight requirement of the electric vehicle on-board unit, the LCC-S type circuit topology is determined to be used in the wireless charging system for electric vehicles.

[0073] S2. Based on the applicable vehicle models of the 11kW and 22kW receivers, determine the ground clearance of the 11kW and 22kW receivers, as well as the on-board battery charging voltage and the resonant operating angular frequency w of the input DC voltage.

[0074] S3. Based on the design standards for wireless charging systems for electric vehicles, determine the structural parameters of the transmitter and the minimum coupling coefficient k for all power levels in the applicable design standards. min and the maximum coupling coefficient k max (The scanning range of the coupling coefficient k is k) min To k max ), and the compensation inductor L at the transmitting end. f The scanning range;

[0075] S4. Determine the lower limit of system transmission efficiency η min And in satisfying η min Under the given conditions, within the parameter range determined in step S3, the compensation inductor L is determined. f The selectable range and the range of values ​​for the coupling coefficient k;

[0076] S5. Under the electrical parameter stress constraints at the transmitting and receiving ends, the compensation inductance L determined in step S4... f From the selectable range, determine the compensation inductance L. f The range of values ​​for;

[0077] S6, in the compensation inductor L f Determine L within the range of values. f The specific value is determined based on the resonance relationship, which sets the parameter value of the transmitter compensation capacitor.

[0078] S7. Within the range of the coupling coefficient k, and in accordance with the design standards, determine the structural parameters of the coils for the 11kW and 22kW receivers and the parameter values ​​of the compensation capacitors for the receivers.

[0079] S8. Perform simulation based on the determined system parameters to obtain the system output and determine whether the output requirements are met. If not, return to step S6 to adjust the parameters.

[0080] (1) Regarding step S1

[0081] GB / T38775.6 specifies a DLCC (Double-sided LCC) compensation network, but does not provide a design for an LCC-S compensation network. Compared to the DLCC type circuit topology, the receiver adopts an S-type topology, which can effectively reduce the number of on-board components and the weight of on-board equipment, meeting the lightweight requirements of electric vehicle on-board units. Therefore, this invention selects the LCC-S type circuit topology. The transmitter adopts an LCC topology, and constant voltage output characteristics can be achieved through topology parameter configuration and operating frequency setting. It also facilitates zero-voltage switching (ZVS), thereby reducing switching losses.

[0082] (2) Regarding step S2, the 11kW power level is mainly applicable to small cars, with a distance range (ground clearance) of 140-210mm between the receiver and transmitter; the 22kW power level is mainly applicable to medium-sized cars, with a distance range of 170-250mm between the receiver and transmitter, and no reference dimensions are currently available. Therefore, this invention selects 160mm and 200mm as the ground clearance of the 11kW and 22kW receiver devices, the vehicle-mounted battery charging voltage is selected as 400V, and the input DC voltage resonant operating frequency w is 85kHz.

[0083] (3) Regarding step S3

[0084] This invention uses the structural parameters of the transmitter in the design standard GB / T38775.6 for wireless charging systems of electric vehicles as a reference. The structure of the ground transmitter coil is as follows: Figure 2 As shown in Table 1, the self-inductance of the transmitting coil is 46.5uH.

[0085] Table 1 Structural parameters of the ground transmitter

[0086]

[0087] The minimum coupling coefficient k for the three power levels WPT1, WPT2 and WPT3 in GB / T38775.6 min =0.10, maximum coupling coefficient k max =0.271, and the reference value L for the transmitter compensation inductance. f =22uH, therefore, given that the input and output voltages and other parameters are fixed, this invention selects the scanning range of the coupling coefficient k as 0.100-0.271, and the compensation inductor L f The scanning range is 10-50uH.

[0088] (4) Regarding step S4

[0089] Step S4 specifically includes the following steps:

[0090] S41. Determine the minimum transmission efficiency η for systems adapted to 11kW and 22kW power levels. min ;

[0091] S42, Simulation to obtain the compensation inductance L f The scanning range of the coupling coefficient k, and the transmission efficiency of the system at power levels of 11kW and 22kW;

[0092] S43. Determine that the transmission efficiency of the system at both 11kW and 22kW power levels is greater than or equal to η. min Compensating inductor L f The range of the compensation inductance L and the range of the coupling coefficient k are given by the range of the compensation inductance L. f The selectable range and the range of values ​​for the coupling coefficient k.

[0093] Meeting system efficiency output requirements is a crucial condition for interoperability design. This invention selects a DC-DC transmission efficiency of 93% as the selection parameter limit, i.e., η. min =93%. Simulations were performed for 11kW and 22kW respectively. Under the condition of meeting the required transmission efficiency, the corresponding parameter L is when the two efficiency output surfaces η1 (11kW) and η2 (22kW) simultaneously satisfy a transmission efficiency greater than or equal to 93%. f If, within the selectable range that satisfies the constraints on k, neither of the two efficiency output surfaces has a portion simultaneously exceeding 93% efficiency, then it is impossible to simultaneously achieve high-efficiency output for both 11kW and 22kW receiver devices. In such cases, the parameters should be redesigned and the range adjusted. Transmitter compensation inductor L f And the simulation results of coupling coefficient k and transmission efficiency are as follows: Figure 3 As shown.

[0094] Depend on Figure 3 Therefore, in order to ensure that the DC-DC transmission efficiency of both the 11kW and 22kW power levels is greater than or equal to 93%, the compensation inductor L... f The selectable range is 12.8uH. <L f <35.4uH, the coupling coefficient k ranges from 0.128. <k<0.271。

[0095] (5) Regarding step S5

[0096] Meanwhile, while ensuring interoperability between the two power levels, the electrical parameters of the transmitting coil should not be excessively stressed; otherwise, it would be difficult to achieve in practice and would lack practical reference value. Therefore, this invention addresses the transmitting coil current I... p and the current I at the receiving end s Perform simulation analysis.

[0097] Step S5 specifically includes the following steps:

[0098] S51. Within the parameter range determined in step S4, simulate and obtain the transmitter current I at power levels of 11kW and 22kW. p Receiver current I s With compensation inductor L f The relationship curve between the coupling coefficient k and the coupling coefficient k;

[0099] S52. Determine the maximum allowable effective current value of the receiving coil according to the design standards, and determine the compensation inductor L based on the relationship curve obtained in step S51, within the limit of the maximum allowable effective current value. f The selection range;

[0100] S53. Within the parameter range determined in step S4, simulate and obtain the voltage U of the two compensation capacitors at the transmitter for power levels of 11kW and 22kW. Cp U Cf With compensation inductor L f The relationship curve between the coupling coefficient k and the coupling coefficient k;

[0101] S54. Determine the maximum voltage of the two compensation capacitors at the transmitting end, and under the constraint of the maximum voltage, determine the compensation inductor L according to the relationship curve obtained in step S53. f The selection range;

[0102] S55, the compensation inductor L determined in steps S52 and S54. f The selected range is combined to obtain the compensation inductance L. f The range of values ​​for .

[0103] Figure 4 For the transmitter current I p and the current I at the receiving end s In both 11kW and 22kW power modes, with compensation inductor L f The relationship curve between the coupling coefficient k and the coil internal resistance allows us to obtain the compensation inductor current I corresponding to 11kW and 22kW from the curve. p1 and I p2 The output characteristics are exactly the same, and are identical to those of the compensation inductor L. f Inversely proportional to the coupling coefficient k, and independent of the output conditions, the current stress on the compensation inductor should be minimized as much as possible. It should be selected based on the actual overcurrent capacity of the coil. In GB / T38775.6, the maximum allowable effective current of the receiving coil is 65A. Therefore, this invention also selects 65A as the maximum allowable current. Thus, the compensation inductor L... f >18.4uH.

[0104] Simultaneously, the voltage U of the compensation capacitor at the transmitting end is... Cp and U Cf Perform simulation. Figure 5Compensation capacitor voltage U at the transmitter for power levels of 11kW and 22kW Cp and U Cf With compensation inductor L f The relationship curve between the coupling coefficient k and the coupling coefficient k.

[0105] Depend on Figure 5 Therefore, the compensation capacitor voltage U is obtained. Cp Size and compensation inductance L f Inversely proportional, independent of k; compensation capacitor voltage U Cf Size and L f Both k and φ are directly proportional. To prevent excessive voltage stress, when the maximum voltage stress of the capacitor is selected as 1000V, then 18.1uH <L f <44.6uH, k<0.271.

[0106] Finally, under the conditions of satisfying output efficiency and electrical stress, L f The selection range is: 18.4uH <L f <35.4uH, the coupling coefficient k ranges from 0.128. <k<0.271。

[0107] (6) Regarding step S6

[0108] To simultaneously adapt to the transmitter in GB / T38775.6, this invention selects the transmitter compensation inductor L. f It is 22uH, that is, L f1 =L f2 =11uH, from equation (5) we can obtain the compensation capacitor C f =159.4nF, C p =143.0nF, then all the resonant parameters of the transmitter have been determined.

[0109] (7) Regarding step S7

[0110] In step S7, the structural parameters of the coil at the 11kW receiver are determined, specifically including the following steps:

[0111] S71. Determine the outer dimensions, side length, and wire diameter of the 11kW receiver coil according to the design standards.

[0112] S72. Simulate and obtain the coupling coefficients corresponding to different coil turns under the outer dimension side length and wire diameter determined in step S71, and filter to obtain the coupling coefficients that satisfy the value range of the coupling coefficient k.

[0113] S73. Determine a specific coupling coefficient value based on the coupling coefficients filtered in step S72, and calculate the corresponding coil self-inductance based on the coupling coefficient value.

[0114] S74. Simulation yields the number of coil turns that satisfy the coil's self-inductance.

[0115] The steps for determining the structural parameters of the coil at the 22kW receiver are the same as steps S71 to S74.

[0116] For electric vehicles, the requirements for miniaturization and lightweighting of the receiver are becoming increasingly stringent, meaning there are certain requirements for the side length D of the receiver's outer dimensions. Adopting GB / T38775.7, for an 11kW device, the reference value for the side length D of the WP3 Z2 receiver in GB / T38775.7 is 320mm, and the receiver wire diameter is selected as 6mm.

[0117] The average value of the coupling coefficients from the simulation in Table 2 is k. 320 =0.167, then the corresponding receiver self-inductance L s =134.7uH. Based on COMSOL simulation, the number of coil turns n = 16, so all parameters of the 11kW device have been determined, as shown in Table 3.

[0118] Table 2 shows the coupling coefficient k for different coil turns n when the outer dimension side length is 320mm. i

[0119] n 10 11 12 13 14 15 16 17 18 19 20 <![CDATA[k i ]]> 0.164 0.165 0.166 0.167 0.168 0.168 0.168 0.168 0.168 0.167 0.165

[0120] Table 3 Parameters of 11kW System

[0121]

[0122] Since there are currently no reference dimensions for the structural parameters of the 22kW power level receiver, this invention selects a 500mm*500mm rounded rectangle structure for the 22kW receiver coil. Following the same design process as the 11kW receiver, the parameters of the 22kW device are shown in Table 4.

[0123] Table 4 Parameters of 22kW System

[0124]

[0125] (8) Regarding step S8

[0126] The determined parameters were then substituted into the 11kW and 22kW circuit models for verification. The load voltage and current output curves of the 11kW and 22kW devices are shown below. Figure 6 Figure 7 As shown, the corresponding DC-DC simulation output efficiencies η1 = 95.08% and η2 = 94.93%, both of which meet the design requirements.

[0127] The simulation results show that, after stabilization, the output voltage U at the load terminal of the 11kW device is... L1=405.2V, 22kW device load terminal output voltage U L2 =402.1V, which meets the load output requirements.

[0128] In summary, the electric vehicle wireless charging system adapted to 11kW and 22kW receivers provided in this embodiment of the invention, based on the LCC-S topology, can effectively reduce the number of on-board components and the weight of on-board equipment, meeting the lightweight requirements of electric vehicle on-board units. Under the national standard-given transmitter size parameters, interoperable electrical parameters are designed for two different power levels, 11kW and 22kW, solving the drawback of one transmitter corresponding to one receiver in electric vehicle wireless charging. The system provides parameter selection ranges for transmitter compensation inductance and system coupling coefficient for the two high-power levels of 11kW and 22kW, while meeting the requirements of high efficiency and reducing electrical stress on components. This allows for the design of a wireless charging system adapted to a unified transmitter, meeting the development needs of wireless electric vehicles.

[0129] 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 considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A wireless charging system for electric vehicles compatible with 11kW and 22kW receivers, characterized in that: It includes a transmitter and a receiver, wherein the receiver is an 11kW receiver or a 22kW receiver; The parameters of the wireless charging system for electric vehicles are determined using the following steps: S1. Based on the constant voltage output requirement and the lightweight requirement of the electric vehicle on-board unit, the electric vehicle wireless charging system adopts the LCC-S type circuit topology. S2. Based on the applicable vehicle models of the 11kW and 22kW receivers, determine the ground clearance of the 11kW and 22kW receivers, as well as the on-board battery charging voltage and the resonant operating angular frequency ω of the input DC voltage. S3. Based on the design standards for wireless charging systems for electric vehicles, determine the structural parameters of the transmitter, the scanning range of the coupling coefficient k applicable to all power levels in the design standards, and the compensation inductance L of the transmitter. f The scanning range; S4. Determine the lower limit of system transmission efficiency η min And in satisfying η min Under the given conditions, within the parameter range determined in step S3, the compensation inductor L is determined. f The selectable range and the range of values ​​for the coupling coefficient k; S5. Under the electrical parameter stress constraints at the transmitting and receiving ends, the compensation inductance L determined in step S4... f From the selectable range, determine the compensation inductance L. f The range of values ​​for; Step S5 specifically includes the following steps: S51. Within the parameter range determined in step S3, simulate and obtain the transmitter current I at power levels of 11kW and 22kW. p Receiver current I s With compensation inductor L f The relationship curve between the coupling coefficient k and the coupling coefficient k; S52. Determine the maximum allowable effective current value of the receiving coil according to the design standard, and determine the compensation inductor L under the constraint of the maximum allowable effective current value, based on the relationship curve obtained in step S51. f The selection range; S53. Within the parameter range determined in step S3, simulate and obtain the voltage U of the two compensation capacitors at the transmitter for power levels of 11kW and 22kW. Cp 、U Cf With compensation inductor L f The relationship curve between the coupling coefficient k and the coupling coefficient k; S54. Determine the maximum voltage of the two compensation capacitors at the transmitting end, and under the constraint of the maximum voltage, determine the compensation inductance L according to the relationship curve obtained in step S53. f The selection range; S55, the compensation inductor L determined in steps S52 and S54. f The selected range and the parameter range determined in step S4 are combined to obtain the compensation inductor L. f The range of values ​​for; S6, in the compensation inductor L f Determine L within the range of values. f The specific value is determined based on the resonance relationship, which sets the parameter value of the transmitter compensation capacitor. S7. Within the range of the coupling coefficient k, and in accordance with the design standards, determine the structural parameters of the coils for the 11kW and 22kW receivers and the parameter values ​​of the compensation capacitors for the receivers.

2. The electric vehicle wireless charging system adapted to 11kW and 22kW receivers according to claim 1, characterized in that, In step S7, the structural parameters of the coil at the 11kW receiver are determined, specifically including the following steps: S71. Determine the outer dimensions, side length, and wire diameter of the 11kW receiving coil according to the design standards. S72. Simulate and obtain the coupling coefficients corresponding to different coil turns under the outer dimension side length and wire diameter determined in step S71, and filter to obtain the coupling coefficients that satisfy the value range of the coupling coefficient k. S73. Determine a specific coupling coefficient value based on the coupling coefficients filtered in step S72, and calculate the corresponding coil self-inductance based on the coupling coefficient value. S74. Simulation yields the number of coil turns that satisfy the coil's self-inductance.

3. The electric vehicle wireless charging system adapted to 11kW and 22kW receivers according to claim 2, characterized in that: In step S7, the step of determining the structural parameters of the coil of the 22kW receiver is the same as in steps S71 to S74.

4. The electric vehicle wireless charging system adapted to 11kW and 22kW receivers according to claim 3, characterized in that, Step S4 specifically includes the following steps: S41. Determine the minimum transmission efficiency η for systems adapted to 11kW and 22kW power levels. min ; S42, Simulation to obtain the compensation inductance L f The scanning range of the coupling coefficient k, and the transmission efficiency of the system at power levels of 11kW and 22kW; S43. Determine that the transmission efficiency of the system at both 11kW and 22kW power levels is greater than or equal to η. min Compensating inductor L f The range of the compensation inductance L and the range of the coupling coefficient k are given by the range of the compensation inductance L. f The selectable range and the range of values ​​for the coupling coefficient k.

5. The electric vehicle wireless charging system adapted to 11kW and 22kW receivers according to any one of claims 1 to 4, characterized in that, The step S7 is followed by the following step: S8. Perform simulation based on the determined system parameters to obtain the system output and determine whether the output requirements are met. If not, return to step S6 to adjust the parameters.

6. The electric vehicle wireless charging system adapted to 11kW and 22kW receivers according to claim 5, characterized in that, In steps S6 and S7, the parameter values ​​of the transmitting end compensation capacitor and the receiving end compensation capacitor are determined according to the following formula: Among them, C f Indicates the connection with the transmitting coil L p Parallel compensation capacitors, C p Indicates the connection with the transmitting coil L p Series-connected compensation capacitor, L s Indicates the receiving coil, C s Indicates the connection with the receiving coil L s Compensating capacitors connected in series.

7. The electric vehicle wireless charging system adapted to 11kW and 22kW receivers according to claim 6, characterized in that: The compensation inductor L f Split into two L values ​​with equal sensitivity f1 and L f2 They are connected in series with the two output terminals of the high-frequency inverter circuit at the transmitting end and the compensation capacitor C, respectively. f between.

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