Wireless charging system and application method

Abstract

This invention relates to the field of wireless charging technology, and more particularly to a wireless charging system and application method. The system includes: m inverters, m-1 RIITs, and a transmitting coil at the GA end; and n first rectifiers, n-1 corresponding RIITs for the first rectifiers, q second rectifiers, q corresponding RIITs for the second rectifiers, and a receiving coil at the VA end. The outputs of the n first rectifiers are connected in parallel to output power to the high-voltage battery; the outputs of the q second rectifiers are connected in parallel to output power to the low-voltage battery. Both the high-voltage and low-voltage batteries are powered through the receiving coil at the VA end. By setting the operating state of the rectifiers, the charging mode can be changed, achieving decoupled control of charging the high-voltage and low-voltage batteries. This invention effectively reduces the size and cost of the charging structure at the VA end, and by adjusting the number of inverters and rectifiers, it can accommodate different power requirements.

Description

Technical Field

[0001] This invention relates to the field of wireless charging technology, and in particular to a wireless charging system and its application method. Background Technology

[0002] Electric drive, as a crucial component of green transportation, is gradually replacing traditional fuel-powered vehicles to achieve low-carbon travel goals. Wireless Power Transfer (WPT), also known as wireless charging, achieves contactless energy transfer through electromagnetic coupling. This system boasts significant advantages such as high safety, ease of operation, and strong reliability, demonstrating broad application prospects in the charging field. As a core component of energy supply for transportation electrification, the optimization of wireless charging systems plays a vital role in alleviating range anxiety and improving user satisfaction.

[0003] The charging system for transportation vehicles comprises two types of batteries: a high-voltage battery that powers the system's operation and a low-voltage battery that powers lighting, air conditioning, and other auxiliary equipment. Existing wireless charging systems generally employ a single energy transfer path design: the high-voltage battery receives power directly through the WPT system, while the low-voltage battery is charged via an auxiliary power module (APM) from the high-voltage battery. This architecture has several technical drawbacks: First, the additional APM increases the system's size and weight, hindering compact design and reducing system integration. Second, the multi-stage energy conversion leads to increased energy loss, reducing overall system efficiency; furthermore, the low-voltage battery's complete reliance on the high-voltage battery raises concerns about system reliability. These issues limit the improvement of energy efficiency and performance optimization in wireless charging systems and urgently require optimization and improvement. Summary of the Invention

[0004] This application provides a wireless charging system and application method, which solves the technical problems of low energy efficiency and poor performance of wireless charging systems in the charging process of low-voltage and high-voltage batteries in the prior art. It realizes that both high-voltage and low-voltage batteries are powered by the transmitting coil of the wireless charging system, and achieves decoupled control of charging of high-voltage and low-voltage batteries. It can significantly reduce system complexity and cost, improve system integration, optimize system charging efficiency and charging performance, and improve system reliability.

[0005] In a first aspect, embodiments of the present invention provide a wireless charging system, comprising: m inverters at the ground-side GA end, a resonant inductor integrated transformer RIIT, and two rectifier groups at the vehicle-side VA end, where m ≥ 2; the two rectifier groups are respectively a first rectifier group and a second rectifier group, the first rectifier group comprising n first rectifiers, where n ≥ 2, and the second rectifier group comprising q second rectifiers, where q ≥ 1;

[0006] The input terminals of m inverters are connected in parallel. The output terminal of the first inverter is connected in series to the secondary winding of the RIIT at the GA terminal. The output terminals of each inverter other than the first inverter are connected to the primary winding of the RIIT at the GA terminal. The secondary windings of the RIIT at the GA terminal are connected in series. Based on the output terminal of the first inverter and the secondary winding of the RIIT at the GA terminal, the GA terminal series branch of the RIIT at the GA terminal is obtained. The GA terminal series branch is connected in parallel with the parallel resonant capacitor of the first LCC resonant circuit of the RIIT at the GA terminal. The parallel resonant capacitor in the first LCC resonant circuit is connected in parallel with the series resonant capacitor and the transmitting coil in the first LCC resonant circuit. The resonant inductance of the first LCC resonant circuit is provided by the series leakage inductance of the secondary windings of all the RIITs at the GA terminal.

[0007] The transmitting coil at the GA end is electromagnetically coupled to the receiving coil at the VA end.

[0008] In the first rectifier group, the input terminal of the first first rectifier is connected in series to the secondary winding of the RIIT at the VA terminal, and the input terminal of each first rectifier other than the first first rectifier is connected to the primary winding of the RIIT at the VA terminal; the input terminal of each second rectifier in the second rectifier group is connected to the primary winding of the RIIT at the VA terminal; the secondary windings of the RIIT at the VA terminal are connected in series; based on the input terminal of the first first rectifier and the secondary winding of the RIIT at the VA terminal, the VA terminal series branch of the RIIT at the VA terminal is obtained; the VA terminal series branch is connected in parallel with the parallel resonant capacitor of the second LCC resonant circuit of the RIIT at the VA terminal; the parallel resonant capacitor in the second LCC resonant circuit is connected in parallel with the series resonant capacitor and the transmitting coil connected in series in the second LCC resonant circuit; wherein, the resonant inductance of the second LCC resonant circuit is provided by the series leakage inductance of all the secondary windings of the RIIT at the VA terminal.

[0009] The output terminals of the first rectifiers in the first rectifier group are connected in parallel to output electrical energy to the high-voltage battery.

[0010] The output terminals of the second rectifiers in the second rectifier group are connected in parallel to output electrical energy to the low-voltage battery, wherein the voltage of the high-voltage battery is greater than the voltage of the low-voltage battery;

[0011] The value of m is determined based on the output power of the wireless charging system and the rated transmission power of each inverter, the value of n is determined based on the rated transmission power of each of the first rectifiers and the rated power of the high-voltage battery, and the value of q is determined based on the rated transmission power of each of the second rectifiers and the rated power of the low-voltage battery.

[0012] Preferably, the resonant inductance L of the first LCC resonant circuit f_ga for:

[0013] ;

[0014] in, The leakage inductance of the RIIT of the i-th inverter at the GA terminal;

[0015] The resonant inductor of the second LCC resonant circuit for:

[0016] ;

[0017] in, The leakage inductance of the j-th first rectifier at the VA terminal is the RIIT leakage inductance. The leakage inductance of the kth second rectifier at the VA terminal is RIIT.

[0018] Preferably, the equivalent input voltage v of the first LCC resonant circuit inv for:

[0019] ;

[0020] in, The output voltage of the first inverter, Let i be the output voltage of the i-th inverter. The RIIT ratio for each inverter other than the first inverter;

[0021] Input voltage of the first rectifier group for:

[0022] ;

[0023] in, The input voltage of the first rectifier is the first one. The input voltage of the j-th first rectifier is... The transformation ratio of RIIT for each of the first rectifiers except the first first rectifier;

[0024] Input voltage of the second rectifier group for:

[0025] ;

[0026] in, The input voltage of the kth second rectifier is... The transformation ratio of the RIIT corresponding to each of the second rectifiers.

[0027] Preferably, the wireless charging system is used in the following way: in working mode one, both the first rectifier group and the second rectifier group adopt phase shift control. During the phase shift control process in working mode one, the phase shift angle of each first rectifier is 2α and the phase shift angle of each second rectifier is 2β, so as to realize independent control of the high voltage output of the first rectifier group and the low voltage output of the second rectifier group.

[0028] In operating mode two, only the first rectifier group uses phase shift control. During the phase shift control process in operating mode two, the phase shift angle of each first rectifier is 2α.

[0029] In operating mode three, only the second rectifier group uses phase-shift control, and during the phase-shift control process in operating mode three, the phase-shift angle of each second rectifier is 2β.

[0030] Preferably, the wireless charging system is used for:

[0031] During the phase-shift control process in the operating mode, the output voltage of the first rectifier group... and output power They are respectively:

[0032] ;

[0033] ;

[0034] Where M is the mutual inductance between the transmitting coil and the receiving coil. The DC bus voltage at the GA terminal. The resistance of the high-voltage battery is... Defined as and The phase angle between them The DC bus current at the VA terminal is... This refers to the DC bus voltage of the battery corresponding to the operating mode. The angular frequency at which the system operates.

[0035] Preferably, the wireless charging system is used for:

[0036] During the phase-shift control process in the operating mode, the output voltage of the second rectifier group... and output power They are respectively:

[0037] ;

[0038] ;

[0039] in, The resistance of the low-voltage battery is given.

[0040] Preferably, the total power loss of the wireless charging system is:

[0041] ;

[0042] ;

[0043] ;

[0044] ;

[0045] in, The total power loss of the wireless charging system. This represents the total power loss of the m inverters. The output current is formed by the m inverters and all RIITs at the GA terminals. The on-resistance of each switching transistor in the inverter, the first rectifier, and the second rectifier. This represents the total power loss of the first rectifier group and the second rectifier group. The voltage drop of each diode in the first rectifier, The voltage drop across each diode in the second rectifier. The rated power of the high-voltage battery, The rated power of the low-voltage battery, This represents the power loss of all the RIITs mentioned. For the iron loss of all the RIITs mentioned, and These are the primary and secondary internal resistances of the RIIT at the GA terminal, respectively. and These are the primary-side internal resistance and secondary-side internal resistance of the RIIT corresponding to the first rectifier group at the VA terminal, respectively. and These are the primary-side internal resistance and secondary-side internal resistance of the RIIT corresponding to the second rectifier group at the VA terminal, respectively. The internal resistance of the transmitting coil is given. The internal resistance of the receiving coil is... This forms the overall input current for all rectifiers and all RIITs at the VA terminals.

[0046] Optionally, the output power of the wireless charging system for: ;

[0047] The charging efficiency η of the wireless charging system is: , The total power loss of the wireless charging system.

[0048] Optionally, the wireless charging system is also used for:

[0049] The inverter, the first rectifier group, and the second rectifier group are all controlled to operate at a 50% duty cycle, and the output voltage of each inverter is determined according to Fourier series expansion. Input voltage of each of the first rectifiers and the input voltage of each of the second rectifiers The expressions are shown below;

[0050] ;

[0051] ;

[0052] ;

[0053] in, The output voltage of the first rectifier group is... The output voltage of the second rectifier group is... This refers to the DC bus voltage at the GA terminal.

[0054] Based on the same inventive concept, in a second aspect, the present invention also provides an application method for a wireless charging system, used to implement the wireless charging system described in the first aspect, the application method comprising:

[0055] Obtain the key parameters of the system, including: the rated voltage and rated power of the high-voltage battery, the rated voltage and rated power of the low-voltage battery, the distance between the transmitting coil and the receiving coil, and the volume parameters of the system;

[0056] Based on the key parameters, a magnetic coupling model is obtained, wherein the magnetic coupling model includes: the transmitting coil, the receiving coil, the first LCC resonant circuit, and the second LCC resonant circuit;

[0057] Based on the heat dissipation conditions of the system, determine the maximum transmitting current of the transmitting coil and the maximum receiving current of the receiving coil;

[0058] Based on the rated power of the high-voltage battery and the rated power of the low-voltage battery, determine the number of inverters m, the number of first rectifiers n, and the number of second rectifiers q.

[0059] Select the operating frequency of the system and determine the resonance parameters of the first LCC resonant circuit and the second LCC resonant circuit;

[0060] Based on the resonance parameters of the first LCC resonant circuit and the second LCC resonant circuit, the resonant inductor integrated transformer RIIT is determined, and finally the system is formed.

[0061] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0062] In the architecture of the wireless charging system of this invention, the low-voltage battery can directly transmit energy through the coupling coil, significantly improving charging efficiency and achieving an optimized balance in charging performance between the high-voltage and low-voltage batteries. By sharing active components (inverters) and passive components (resonant inductors and resonant capacitors), the size and cost of the charging structure at the VA end are effectively reduced. The system of this invention supports simultaneous charging and individual charging of high-voltage and low-voltage batteries, meeting different charging needs under different operating conditions and significantly improving the system's flexibility and compatibility. Furthermore, the system capacity can be flexibly adjusted by changing the number of functional units, i.e., m inverters, n first rectifiers, and q second rectifiers. The system of this invention can also directly adopt a WPT coil structure without additional modification or redesign of the WPT coil, ensuring energy transmission power while reducing the complexity of engineering implementation. Thus, the wireless charging system of this invention integrates the wireless charging technology WPT with the power module of the auxiliary equipment, realizing the power supply function of both high-voltage and low-voltage batteries. This simplifies the system's size and reduces its weight, resulting in a compact layout, high integration, high charging efficiency, excellent scalability, and improved performance and energy efficiency. Attached Figure Description

[0063] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0064] Figure 1 A schematic diagram of the circuit structure of a wireless charging system according to an embodiment of the present invention is shown;

[0065] Figure 2 A schematic diagram of the equivalent circuit structure of the wireless charging system in an embodiment of the present invention is shown.

[0066] Figure 3 An equivalent circuit diagram of the wireless charging system in operating mode one according to an embodiment of the present invention is shown;

[0067] Figure 4 An equivalent circuit diagram of the wireless charging system in operating mode two according to an embodiment of the present invention is shown;

[0068] Figure 5 An equivalent circuit diagram of the wireless charging system in operating mode three of the embodiments of the present invention is shown;

[0069] Figure 6 The state curves of the inverter and rectifier in an embodiment of the present invention are shown.

[0070] Figure 7 A flowchart illustrating the steps of an application method for a wireless charging system according to an embodiment of the present invention is shown. Detailed Implementation

[0071] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0072] Example 1

[0073] The first embodiment of the present invention provides a wireless charging system, such as... Figure 1As shown, the system includes: m inverters at the ground-side GA terminal, a resonant inductor integrated transformer (RIIT), and two rectifier groups at the vehicle-side VA terminal, where m ≥ 2. The two rectifier groups are designated as the first rectifier group and the second rectifier group. The first rectifier group comprises n first rectifiers, n ≥ 2, and the second rectifier group comprises q second rectifiers, q ≥ 1. It should be noted that the first and second rectifiers are of the same specification type, and the q second rectifiers can be numbered from n+1, n+2, ..., up to n+q.

[0074] exist Figure 1 In the diagram, #1 inverter represents the first inverter, #2 inverter represents the second inverter, and so on. The input terminals of the m inverters are connected in parallel to connect to the DC bus voltage of the GA terminal. The output of the first inverter out of m inverters is connected in series with the secondary winding of the RIIT at the GA end. The output of each inverter other than the first inverter is connected to the primary winding of the RIIT at the GA end, and the secondary windings of the RIITs at the GA end are connected in series. Based on the output of the first inverter and the secondary windings of the RIITs at the GA end, the GA end series branch of the RIITs at the GA end is obtained, that is, the branch formed by the output of the first inverter and the secondary windings of all the RIITs at the GA end connected in series. The GA end series branch is connected in parallel with the parallel resonant capacitor Cf_ga of the first LCC resonant circuit of the RIITs at the GA end. The parallel resonant capacitor Cf_ga in the first LCC resonant circuit is connected in parallel with the series resonant capacitor Cga connected in series in the first LCC resonant circuit and the transmitting coil. The resonant inductance of the first LCC resonant circuit is provided by the series leakage inductance of the secondary windings of all the RIITs at the GA end.

[0075] The transmitting coil at the GA end and the receiving coil at the VA end are electromagnetically coupled together. The transmitting coil and the receiving coil form the WPT (Wireless Power Transfer) coil of the wireless charging system in this embodiment.

[0076] exist Figure 1In the diagram, #1 represents the first rectifier, #2 represents the second rectifier, and so on. Similarly, #1 represents the first second rectifier, #2 represents the second second rectifier, and so on. In the first rectifier group, the input terminal of the first rectifier is connected in series with the secondary winding of the RIIT at the VA terminal. The input terminal of each rectifier other than the first rectifier is connected to the primary winding of the RIIT at the VA terminal. In the second rectifier group, the input terminal of each second rectifier is connected to the primary winding of the RIIT at the VA terminal. The secondary windings of the RIIT at the VA terminal are connected in series. Based on the input terminal of the first rectifier and the secondary windings of the RIIT at the VA terminal, the VA terminal series branch of the RIIT at the VA terminal is obtained, which is the branch formed by the input terminal of the first rectifier and the secondary windings of all the RIITs at the VA terminal connected in series. The parallel resonant capacitor C of the VA terminal series branch and the second LCC resonant circuit of the RIIT at the VA terminal is... f_va Parallel connection. The parallel resonant capacitor C in the second LCC resonant circuit. f_va The series resonant capacitor C connected in series with the second LCC resonant circuit va It is connected in parallel with the transmitting coil. The resonant inductance of the second LCC resonant circuit is provided by the series connection of the secondary leakage inductance of all RIITs at the VA terminal.

[0077] The output terminals of the first rectifier in the first rectifier group are connected in parallel to supply power to the high-voltage battery. The high-voltage battery includes, but is not limited to, the power battery of an electric vehicle. The output terminals of the second rectifier in the second rectifier group are connected in parallel to supply power to the low-voltage battery. The low-voltage battery is an auxiliary device battery, including, but not limited to, batteries for lighting, air conditioning, or other auxiliary equipment. The voltage of the high-voltage battery is greater than the voltage of the low-voltage battery; for example, the supply voltage of the high-voltage battery is greater than the supply voltage of the low-voltage battery.

[0078] m is determined based on the output power of the wireless charging system and the rated transmission power of each inverter, n is determined based on the rated transmission power of each first rectifier and the rated power of the high-voltage battery, and q is determined based on the rated transmission power of each second rectifier and the rated power of the low-voltage battery.

[0079] In the architecture of the wireless charging system of this embodiment, the low-voltage battery can directly transmit energy through the coupling coil, significantly improving charging efficiency and achieving an optimized balance in charging performance between the high-voltage and low-voltage batteries. By sharing active components (inverters) and passive components (resonant inductors and resonant capacitors), the size and cost of the charging structure at the VA end are effectively reduced. The system of this embodiment supports simultaneous charging and individual charging of high-voltage and low-voltage batteries, meeting different charging needs under different operating conditions and significantly improving the system's flexibility and compatibility. Furthermore, the system capacity can be flexibly adjusted by changing the number of functional units, i.e., m inverters, n first rectifiers, and q second rectifiers. The system of this embodiment can also directly adopt the WPT coil structure without additional modification or redesign of the WPT coil, ensuring energy transmission power while reducing the complexity of engineering implementation. Thus, the wireless charging system of this embodiment integrates the wireless charging technology WPT with the power module of the auxiliary equipment, realizing the power supply function of both high-voltage and low-voltage batteries. This simplifies the system's size, reduces its weight, and results in a compact layout, high integration, high charging efficiency, excellent scalability, and improved performance and energy efficiency. Furthermore, in applications with known requirements, the system can be carefully designed to optimize the number of inverters and rectifiers, as well as the turns ratio of the RIIT, to achieve the target output power. Specifically, the structural optimization of eliminating the need for connecting the first inverter and the first rectifier to the transformer RIIT significantly reduces costs, size, and weight while ensuring normal system operation. Moreover, by eliminating the inherent losses of these two RIITs, the system's peak efficiency is improved.

[0080] Below, in conjunction with Figure 1 This embodiment describes the wireless charging system and its principle in detail:

[0081] In the wireless charging system of this embodiment, each inverter can be a full-bridge inverter, and each rectifier (i.e., the first rectifier and the second rectifier) ​​can be a semi-bridgeless rectifier. For example... Figure 1 As shown, taking the first inverter and the first rectifier as examples, each inverter includes: switching transistors S11, S21, S31, and S41, and an inverter capacitor. The drain of switching transistor S11, the drain of switching transistor S21, and one end of the inverter capacitor are all connected to the first input port of the inverter. The source of switching transistor S31, the source of switching transistor S41, and the other end of the inverter capacitor are all connected to the second input port of the inverter. The source of switching transistor S11 and the drain of switching transistor S31 are both connected to the first output port of the inverter, and the source of switching transistor S21 and the drain of switching transistor S41 are both connected to the second output port of the inverter. The gates of switching transistors S11, S21, S31, and S41 are all connected to the timing control module of this system (not shown in the attached diagram).

[0082] exist Figure 1 In this circuit, each rectifier includes: a diode D 11 diode D 21 Switching transistor Q 11 Switching transistor Q 21 And rectifier capacitor. Diode D 11 The positive terminal and the switching transistor Q 11 The drain of diode D is connected to the first input port of the rectifier. 21 The positive terminal and the switching transistor Q 21 The drain of diode D is connected to the second input port of the rectifier. 11 negative terminal, diode D 21 The negative terminal and one end of the rectifier capacitor are connected to the first output port of the rectifier, and the switching transistor Q... 11 The source and switch Q 21 The source of the transistor and the other end of the rectifier capacitor are connected to the second output port of the rectifier, and the switching transistor Q... 11 The gate and switch Q 21 The gates of all are connected to the timing control module of the system.

[0083] Based on the architecture of the wireless charging system in this embodiment, the total leakage inductance L of the RIIT at the GA end is... f_ga and ratio m t Total leakage inductance L at the VA end of the RIIT f_va The turns ratio n of the RIIT corresponding to the high-voltage battery t The turns ratio q of the RIIT corresponding to the low-voltage battery t These parameters together constitute the key parameters of the WPT system. The resonant inductance of the first LCC resonant circuit is provided by the series connection of the secondary leakage inductances of all RIITs at the GA terminal. f_ga This is also the resonant inductance of the first LCC resonant circuit. The resonant inductance of the second LCC resonant circuit is provided by the series connection of the secondary leakage inductances of all RIITs at the VA terminal, then L... f_va It is also the resonant inductance of the second LCC resonant circuit.

[0084] The resonant inductor L of the first LCC resonant circuit f_ga for:

[0085] (1);

[0086] in, The leakage inductance of the RIIT of the i-th inverter at the GA terminal.

[0087] The resonant inductor of the second LCC resonant circuit for:

[0088] (2);

[0089] in, For the RIIT leakage inductance of the j-th first rectifier at the VA terminal, The leakage inductance of the RIIT of the kth second rectifier at the VA terminal.

[0090] The equivalent input voltage v of the first LCC resonant circuit inv for:

[0091] (3);

[0092] in, This is the output voltage of the first inverter. Let i be the output voltage of the i-th inverter. This represents the RIIT ratio for each inverter except the first one.

[0093] Input voltage of the first rectifier group for:

[0094] (4);

[0095] in, The input voltage of the first rectifier. Let j be the input voltage of the first rectifier. The transformation ratio of RIIT is the ratio of each first rectifier except the first first rectifier.

[0096] Input voltage of the second rectifier group for:

[0097] or (5);

[0098] in, The input voltage of the k-th second rectifier is... This refers to the transformation ratio of the RIIT corresponding to each second rectifier. Since the first and second rectifiers are rectifiers of the same specification, the numbering of the second rectifiers can start from n+1. The same applies to the following formulas, which will not be repeated here.

[0099] The integrated structure of this embodiment effectively reduces the size and cost of the charging module at the VA end by sharing active components (inverter) and passive components (resonant inductor and resonant capacitor). This embodiment employs a phase-shift control strategy; by changing the phase shift angle 2α of multiple first rectifiers and the phase shift angle 2β of multiple second rectifiers at the VA end, precise regulation of the WPT system's output voltage and power can be achieved, while ensuring that all switching transistors operate in zero-voltage switching (ZVS) mode.

[0100] In the system architecture of this embodiment, the control inverter, the first rectifier group, and the second rectifier group all adopt a 50% duty cycle, and according to the Fourier series expansion, the output voltage of each inverter is... Input voltage of each first rectifier and the input voltage of each second rectifier The expressions are shown below;

[0101] (6);

[0102] (7);

[0103] (8);

[0104] in, This is the output voltage of the first rectifier group. This is the output voltage of the second rectifier group. This is the DC bus voltage at the GA terminal.

[0105] The equivalent AC resistance of the first rectifier group Equivalent AC resistance of the second rectifier group They are respectively:

[0106] (9);

[0107] (10).

[0108] in, Defined as I va With V rec The phase angle between them This refers to the DC bus current at terminal VA. This is the DC bus voltage of the battery corresponding to the operating mode.

[0109] The wireless charging system in this embodiment operates in the following modes:

[0110] In operating mode one, both the first rectifier group and the second rectifier group adopt phase shift control. During the phase shift control process in operating mode one, the phase shift angle of each first rectifier is 2α and the phase shift angle of each second rectifier is 2β, so as to realize independent control of the high voltage output of the first rectifier group and the low voltage output of the second rectifier group.

[0111] In operating mode two, only the first rectifier group uses phase-shift control. During the phase-shift control process in operating mode two, the phase shift angle of each first rectifier is 2α. The second rectifier group is in bypass mode.

[0112] In operating mode three, only the second rectifier group uses phase-shift control. During the phase-shift control process in operating mode three, the phase shift angle of each second rectifier is 2β. The first rectifier group is in bypass mode.

[0113] Below, in conjunction with Figure 1 The equivalent diagram, i.e. Figures 2-5 The working modes of the wireless charging system are described below:

[0114] exist Figure 2 In the middle, the output voltage of each inverter Equivalent to each power supply voltage The leakage inductance of the RIIT at the GA end is ,Right now - , The leakage inductance of the RIIT at the VA terminal corresponding to the high-voltage battery is... ,Right now - , The leakage inductance of the RIIT at the VA terminal corresponding to the low-voltage battery is... ,Right now - , The first rectifier is equivalent to a resistor. - The second rectifier is equivalent to a resistor. - .

[0115] like Figure 3 The diagram shown represents the equivalent of operating mode one, in which the wireless charging system simultaneously charges both the high-voltage and low-voltage batteries. Both the first and second rectifier groups employ phase-shift control. By adjusting the phase shift angle 2α of the first rectifier and the phase shift angle 2β of the second rectifier, independent control of the output from the high-voltage and low-voltage batteries is achieved. In other words, the first and second rectifier groups utilize phase-shift control to achieve the desired output voltage.

[0116] exist Figure 3In this context, the connection relationship of m inverters is equivalent to the power supply voltage V. inv =v inv The positive terminal is connected to the resonant inductor L of the first LCC resonant circuit. f_ga One end, the negative terminal is connected to resistor R. f_ga One end. The resonant inductance L of the first LCC resonant circuit. f_ga The other end is connected to the parallel resonant capacitor C of the first LCC resonant circuit. f_ga One end, resistor R f_ga The other end is connected to the GA terminal and a resonant capacitor C is connected in parallel. f_ga The other end. Parallel resonant capacitor C f_ga Series resonant capacitor C connected in series ga Transmitting coil L ga and resistance R ga Parallel connection. The parallel resonant capacitor C of the second LCC resonant circuit. f_va Resistor R connected in series va Receiver coil L va The series resonant capacitor C of the second LCC resonant circuit va Parallel connection. The resonant inductance L of the second LCC resonant circuit connected in series. f_va The equivalent AC resistance R of the first rectifier group eq1 The equivalent AC resistance R of the second rectifier group eq2 Resistance R f_va Parallel resonant capacitor C of the second LCC resonant circuit f_va Parallel connection. Where the voltage V... rec =V H +V L This indicates that the DC bus voltage of the battery at this time is the sum of the DC bus voltage of the high-voltage battery and the DC bus voltage of the low-voltage battery.

[0117] In operating mode one, the output voltage of the first rectifier group... and output power and the output voltage of the second rectifier group and output power They are respectively:

[0118] (11); (13);

[0119] (12); (14);

[0120] Where M is the mutual inductance between the transmitting coil and the receiving coil. This is the DC bus voltage at the GA terminal. The resistor is that of the high-voltage battery. The resistance of the low-voltage battery. Defined as and The phase angle between them This refers to the DC bus current at terminal VA. This refers to the DC bus voltage of the battery corresponding to operating mode one. This is the angular frequency at which the system operates.

[0121] like Figure 4 The equivalent diagram for operating mode two is shown. In operating mode two, the wireless charging system only charges the high-voltage battery, while the second rectifier group corresponding to the low-voltage battery is in bypass mode. Therefore, only the first rectifier group uses phase-shift control. Figure 4 middle, Figure 4 Equivalent circuit of the GA terminal and Figure 3 The equivalent circuit of the GA terminal is the same. Figure 4 The difference in the equivalent circuit of the middle VA terminal is that it is only the resonant inductance L of the second LCC resonant circuit connected in series. f_va The equivalent AC resistance R of the first rectifier group eq1 Resistance R f_va Parallel resonant capacitor C of the second LCC resonant circuit f_va Parallel connection.

[0122] In operating mode two, the output voltage of the first rectifier group As shown in formula (11) and output power As shown in formula (12):

[0123] (11);

[0124] (12).

[0125] In operating mode two, the second rectifier group is bypassed, and only the first rectifier group uses phase-shift control. Energy is supplied to the first rectifier group via a magnetic coupling path, enabling separate charging of the high-voltage battery. This reduces the number of operating rectifiers within the battery's rated power range, while the bypassed rectifiers generate virtually no losses, thus significantly improving overall system efficiency and optimizing system performance.

[0126] like Figure 5 The equivalent diagram for operating mode three is shown. In operating mode three, the wireless charging system only charges the low-voltage battery, and the first rectifier group corresponding to the high-voltage battery is in bypass mode. Therefore, only the second rectifier group uses phase-shift control. Figure 5 middle, Figure 5 Equivalent circuit of the GA terminal and Figure 3 The equivalent circuit of the GA terminal is the same. Figure 5The difference in the equivalent circuit of the middle VA terminal is that it is only the resonant inductance L of the second LCC resonant circuit connected in series. f_va The equivalent AC resistance R of the second rectifier group eq2 Resistance R f_va Parallel resonant capacitor C of the second LCC resonant circuit f_va Parallel connection.

[0127] In operating mode three, the output voltage of the second rectifier group... As shown in formula (13) and output power As shown in formula (14):

[0128] (13);

[0129] (14).

[0130] In operating mode three, the first rectifier group is bypassed, and only the second rectifier group uses phase-shift control. Energy is supplied to the second rectifier group via a magnetic coupling path, enabling separate charging of the low-voltage battery. This reduces the number of operating rectifiers within the battery's rated power range, while the bypassed rectifiers generate virtually no losses, thus significantly improving overall system efficiency and optimizing system performance.

[0131] Therefore, during the phase-shift control process in the operating mode, the output voltage of the first rectifier group... and output power As shown in formulas (11) and (12) respectively, the output voltage of the second rectifier group and output power As shown in formulas (13) and (14) respectively,

[0132] The total power loss of the wireless charging system is:

[0133] (15);

[0134] (16);

[0135] (17);

[0136] (18);

[0137] Among them, P loss P represents the total power loss of the wireless charging system. inv I represents the total power loss of m inverters. inv The output current formed by the m inverters and all RIITs at the GA terminals is the input current of the first LCC resonant circuit, R.dson P is the on-resistance of each switch in the inverter, the first rectifier, and the second rectifier. rec V represents the total power loss of the first and second rectifier groups. f1 The voltage drop across the diodes in each of the first rectifiers, V f2 P is the voltage drop across the diodes in each of the second rectifiers. H P is the rated power of the high-voltage battery. L P is the rated power of the low-voltage battery. RIIT P represents the power loss of all RIITs. T For the iron loss of all RIITs, R s1 and R p1 These are the primary and secondary internal resistances of the RIIT at the GA terminal, respectively. s2 and R p2 These are the primary and secondary internal resistances of the RIIT corresponding to the first rectifier group at the VA terminal, R. s3 and R p3 These are the primary and secondary internal resistances of the RIIT corresponding to the second rectifier group at the VA terminal, R. ga R is the internal resistance of the transmitting coil. va I is the internal resistance of the receiving coil. rec This forms the overall input current for all rectifiers and all RIIT terminals at the VA end, which is also the output current of the second LCC resonant circuit. It should also be noted that in this embodiment, the rated power and output power are the same, and are therefore represented by the same letter. For example, P... H P represents the rated power of the high-voltage battery and also the output power of the first rectifier group in operating mode. L This is the rated power of the low-voltage battery, and also the output power of the second rectifier group in operating mode.

[0138] Output power of wireless charging system for: (19); Formula (19) The output power of the wireless charging system varies depending on the working mode. Different. The charging efficiency η of a wireless charging system is: (20).

[0139] like Figure 6As shown, the state curves of the four switches of the inverter are the state curves of switch S1i, switch S2i, switch S3i, and switch S4i, respectively. The state curves of the two switches of the first rectifier are the state curves of switch Q1j and switch Q2j, respectively. The state curves of the two switches of the second rectifier are the state curves of switch Q1(n+k) and switch Q2(n+k), respectively. In any working mode of the wireless charging system, all inverters and rectifiers use a 50% duty cycle. Both types of rectifiers (i.e., the first rectifier group and the second rectifier group) use phase-shift control, that is, there is a delay between the switching action of the two rectifiers and the switching action of the inverter. This delay is the phase shift angle. By adjusting the phase shift angle 2α of the first rectifier and the phase shift angle 2β of the second rectifier, that is, the relationship between voltage and phase shift angle in equations (11) and (13) exists, independent control of high voltage output and low voltage output is achieved, while ensuring that all switches work in ZVS state.

[0140] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0141] (1) Through the architecture of the wireless charging system in this embodiment, the system capacity can be flexibly adjusted by increasing or decreasing the number of power units, i.e., m inverters, n first rectifiers and q second rectifiers. The system in this embodiment supports three working modes: simultaneous charging of high-voltage and low-voltage batteries, charging of high-voltage batteries alone, and charging of low-voltage batteries alone, which significantly improves the flexibility and compatibility of the charging system.

[0142] (2) The system in this embodiment directly adopts the existing coil structure of the WPT system, without the need for additional modification or redesign of the coil, which ensures the power of energy transmission and reduces the complexity of engineering implementation.

[0143] (3) The low-voltage battery can directly transmit energy through the coupling coil, which significantly improves the charging efficiency and achieves an optimized balance of charging performance between the high-voltage battery and the low-voltage battery.

[0144] Example 2

[0145] Based on the same inventive concept, the second embodiment of the present invention also provides an application method for a wireless charging system, used to implement the wireless charging system of embodiment one, such as... Figure 7 As shown, the application method includes:

[0146] S101, Obtain the key parameters of the system, wherein the key parameters include: the rated voltage and rated power of the high-voltage battery, the rated voltage and rated power of the low-voltage battery, the distance between the transmitting coil and the receiving coil, and the volume parameters of the system;

[0147] S102, Based on the key parameters, a magnetic coupling model is obtained, wherein the magnetic coupling model includes: the transmitting coil, the receiving coil, the first LCC resonant circuit, and the second LCC resonant circuit;

[0148] S103, Based on the heat dissipation conditions of the system, determine the maximum transmitting current of the transmitting coil and the maximum receiving current of the receiving coil to evaluate the system performance;

[0149] S104, based on the rated power of the high-voltage battery and the rated power of the low-voltage battery, determine the number of inverters m, the number of first rectifiers n, and the number of second rectifiers q;

[0150] S105, Select the operating frequency of the system and determine the resonance parameters of the first LCC resonant circuit and the second LCC resonant circuit;

[0151] S106, based on the resonance parameters of the first LCC resonant circuit and the second LCC resonant circuit, the resonant inductor integrated transformer RIIT is determined, and finally the system is formed. This makes the total leakage inductance of RIIT at the GA terminal and RIIT at the VA terminal reach the resonant inductance value, and achieves the desired voltage gain through the turns ratio (i.e., turns ratio) of RIIT.

[0152] Specifically, in step S101, the rated voltage of the battery is the voltage required by the battery during design, and the output voltage of the battery is the voltage output during charging; both values ​​are the same. Based on the rated power of the high-voltage battery and the rated power of the low-voltage battery, the output power of the system, i.e., the target charging power, can be determined. In step S102, the magnetic coupling model is a magnetic coupling model formed by components such as the transmitting coil, receiving coil, first LCC resonant circuit, and second LCC resonant circuit, taking into account parameters such as volume, weight, current density, and resonance characteristics. In step S103, the system's heat dissipation conditions are the system's ability to dissipate the heat it generates to the external environment, determined by factors such as the thermal conductivity of the receiving and transmitting coils, the system casing or heat sink, and the external ambient temperature.

[0153] In this embodiment, the application method can quickly and efficiently implement the wireless charging system shown in Embodiment 1, integrating the high-voltage battery with the low-voltage battery of the auxiliary device to achieve power supply functions for both the high-voltage and low-voltage batteries. This simplifies the system's size and reduces its weight, resulting in a compact layout, high integration, high charging efficiency, excellent scalability, and improved performance and energy efficiency. Based on application requirements, the system can achieve dynamic power allocation, enabling on-demand power supply and improving system flexibility and compatibility. It also avoids battery overcharging, which could affect battery lifespan, effectively enhancing system safety and reliability.

[0154] Since the application method of the wireless charging system described in this embodiment is the same as that used in the wireless charging system of Embodiment 1 of this application, those skilled in the art can understand the specific implementation method and various variations of the application method of the wireless charging system in this embodiment based on the wireless charging system described in Embodiment 1 of this application. Therefore, how the application method of this wireless charging system implements the wireless charging system of Embodiment 1 of this application will not be described in detail here. As long as those skilled in the art implement the application method used in the wireless charging system of Embodiment 1 of this application, it falls within the scope of protection of this application.

[0155] Those skilled in the art will understand that although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0156] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A wireless charging system, characterized in that, include: The system consists of m inverters at the ground-side GA end, a resonant inductor integrated transformer RIIT, and two rectifier groups at the vehicle-mounted VA end, where m ≥ 2. The two rectifier groups are a first rectifier group and a second rectifier group, respectively. The first rectifier group includes n first rectifiers, where n ≥ 2, and the second rectifier group includes q second rectifiers, where q ≥ 1. The input terminals of m inverters are connected in parallel. The output terminal of the first inverter is connected in series to the secondary winding of the RIIT at the GA terminal. The output terminals of each inverter other than the first inverter are connected to the primary winding of the RIIT at the GA terminal. The secondary windings of the RIIT at the GA terminal are connected in series. Based on the output terminal of the first inverter and the secondary winding of the RIIT at the GA terminal, the GA terminal series branch of the RIIT at the GA terminal is obtained. The GA terminal series branch is connected in parallel with the parallel resonant capacitor of the first LCC resonant circuit of the RIIT at the GA terminal. The parallel resonant capacitor in the first LCC resonant circuit is connected in parallel with the series resonant capacitor and the transmitting coil in the first LCC resonant circuit. The resonant inductance of the first LCC resonant circuit is provided by the series leakage inductance of the secondary windings of all the RIITs at the GA terminal. The transmitting coil at the GA end is electromagnetically coupled to the receiving coil at the VA end. In the first rectifier group, the input terminal of the first first rectifier is connected in series to the secondary winding of the RIIT at the VA terminal, and the input terminal of each first rectifier other than the first first rectifier is connected to the primary winding of the RIIT at the VA terminal; the input terminal of each second rectifier in the second rectifier group is connected to the primary winding of the RIIT at the VA terminal; the secondary windings of the RIIT at the VA terminal are connected in series; based on the input terminal of the first first rectifier and the secondary winding of the RIIT at the VA terminal, the VA terminal series branch of the RIIT at the VA terminal is obtained; the VA terminal series branch is connected in parallel with the parallel resonant capacitor of the second LCC resonant circuit of the RIIT at the VA terminal; the parallel resonant capacitor in the second LCC resonant circuit is connected in parallel with the series resonant capacitor and the transmitting coil connected in series in the second LCC resonant circuit; wherein, the resonant inductance of the second LCC resonant circuit is provided by the series leakage inductance of all the secondary windings of the RIIT at the VA terminal. The output terminals of the first rectifiers in the first rectifier group are connected in parallel to output electrical energy to the high-voltage battery. The output terminals of the second rectifiers in the second rectifier group are connected in parallel to output electrical energy to the low-voltage battery, wherein the voltage of the high-voltage battery is greater than the voltage of the low-voltage battery; the low-voltage battery is an auxiliary equipment battery, including batteries for lighting and batteries for air conditioning. The m is determined based on the output power of the wireless charging system and the rated transmission power of each inverter; the n is determined based on the rated transmission power of each of the first rectifiers and the rated power of the high-voltage battery; and the q is determined based on the rated transmission power of each of the second rectifiers and the rated power of the low-voltage battery. The structural optimization of the first inverter and the first rectifier without connecting to the RIIT achieves a significant reduction in cost, size and weight while ensuring normal system operation. Furthermore, by eliminating the inherent losses of these two RIITs, the peak efficiency of the system is improved. The inverter uses a 50% duty cycle, and the first rectifier group and the second rectifier group use phase-shift control.

2. The wireless charging system as described in claim 1, characterized in that, The resonant inductance L of the first LCC resonant circuit f_ga for: ； in, The leakage inductance of the RIIT of the i-th inverter at the GA terminal; The resonant inductor of the second LCC resonant circuit for: ； in, The leakage inductance of the j-th first rectifier at the VA terminal is the RIIT leakage inductance. The leakage inductance of the kth second rectifier at the VA terminal is RIIT.

3. The wireless charging system as described in claim 2, characterized in that, The equivalent input voltage v of the first LCC resonant circuit inv for: ； in, The output voltage of the first inverter, Let i be the output voltage of the i-th inverter. The RIIT ratio for each inverter other than the first inverter; Input voltage of the first rectifier group for: ； in, The input voltage of the first rectifier is the first one. The input voltage of the j-th first rectifier is... The transformation ratio of RIIT for each of the first rectifiers except the first first rectifier; Input voltage of the second rectifier group for: ； in, The input voltage of the kth second rectifier is... The transformation ratio of the RIIT corresponding to each of the second rectifiers.

4. The wireless charging system as described in claim 3, characterized in that, The wireless charging system is used in the following way: In working mode one, both the first rectifier group and the second rectifier group adopt phase shift control. During the phase shift control process in working mode one, the phase shift angle of each first rectifier is 2α and the phase shift angle of each second rectifier is 2β, so as to realize independent control of the high voltage output of the first rectifier group and the low voltage output of the second rectifier group. In operating mode two, only the first rectifier group uses phase shift control. During the phase shift control process in operating mode two, the phase shift angle of each first rectifier is 2α. In operating mode three, only the second rectifier group uses phase-shift control, and during the phase-shift control process in operating mode three, the phase-shift angle of each second rectifier is 2β.

5. The wireless charging system as described in claim 4, characterized in that, The wireless charging system is used for: During the phase-shift control process in the operating mode, the output voltage of the first rectifier group... and output power They are respectively: ； ； Where M is the mutual inductance between the transmitting coil and the receiving coil. The DC bus voltage at the GA terminal. The resistance of the high-voltage battery is... Defined as and The phase angle between them The DC bus current at the VA terminal is... This refers to the DC bus voltage of the battery corresponding to the operating mode. The angular frequency at which the system operates.

6. The wireless charging system as described in claim 5, characterized in that, The wireless charging system is used for: During the phase-shift control process in the operating mode, the output voltage of the second rectifier group... and output power They are respectively: ； ； in, The resistance of the low-voltage battery is given.

7. The wireless charging system as described in claim 6, characterized in that, The total power loss of the wireless charging system is: ； ； ； ； in, The total power loss of the wireless charging system. This represents the total power loss of the m inverters. The output current is formed by the m inverters and all RIITs at the GA terminals. The on-resistance of each switching transistor in the inverter, the first rectifier, and the second rectifier. This represents the total power loss of the first rectifier group and the second rectifier group. The voltage drop of each diode in the first rectifier, The voltage drop across each diode in the second rectifier. The rated power of the high-voltage battery, The rated power of the low-voltage battery, This represents the power loss of all the RIITs mentioned. For the iron loss of all the RIITs mentioned, and These are the primary and secondary internal resistances of the RIIT at the GA terminal, respectively. and These are the primary-side internal resistance and secondary-side internal resistance of the RIIT corresponding to the first rectifier group at the VA terminal, respectively. and These are the primary-side internal resistance and secondary-side internal resistance of the RIIT corresponding to the second rectifier group at the VA terminal, respectively. The internal resistance of the transmitting coil is given. The internal resistance of the receiving coil is... This forms the overall input current for all rectifiers and all RIITs at the VA terminals.

8. The wireless charging system as described in claim 6, characterized in that, The output power of the wireless charging system for: ; The charging efficiency η of the wireless charging system is: , The total power loss of the wireless charging system.

9. The wireless charging system as described in claim 4, characterized in that, The wireless charging system is also used for: The inverter, the first rectifier group, and the second rectifier group are all controlled to operate at a 50% duty cycle, and the output voltage of each inverter is determined according to Fourier series expansion. Input voltage of each of the first rectifiers and the input voltage of each of the second rectifiers The expressions are shown below; ； ； ； in, The output voltage of the first rectifier group is... The output voltage of the second rectifier group is... This refers to the DC bus voltage at the GA terminal.

10. An application method of a wireless charging system, characterized in that, The application method for implementing the wireless charging system as described in any one of claims 1-9 includes: Obtain the key parameters of the system, including: the rated voltage and rated power of the high-voltage battery, the rated voltage and rated power of the low-voltage battery, the distance between the transmitting coil and the receiving coil, and the volume parameters of the system; Based on the key parameters, a magnetic coupling model is obtained, wherein the magnetic coupling model includes: the transmitting coil, the receiving coil, the first LCC resonant circuit, and the second LCC resonant circuit; Based on the heat dissipation conditions of the system, determine the maximum transmitting current of the transmitting coil and the maximum receiving current of the receiving coil; Based on the rated power of the high-voltage battery and the rated power of the low-voltage battery, determine the number of inverters m, the number of first rectifiers n, and the number of second rectifiers q. Select the operating frequency of the system and determine the resonance parameters of the first LCC resonant circuit and the second LCC resonant circuit; Based on the resonance parameters of the first LCC resonant circuit and the second LCC resonant circuit, the resonant inductor integrated transformer RIIT is determined, and finally the system is formed.

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