Three-port hybrid energy storage wireless power transfer system and efficiency optimization control method thereof

Abstract

The application discloses a three-port hybrid energy storage wireless power transmission system and an efficiency optimization control method thereof. According to the operation state of an electric vehicle, the system switches the working mode, and for the energy transmission path from the grid side to the high-voltage battery port, the optimal voltage gain and phase difference are obtained by taking the voltage gain and phase difference as variables to derive the efficiency function. For the energy transmission path from the high-voltage battery to the low-voltage battery, the optimal load matching condition is solved by taking the equivalent load as a variable. Through the parameter collaborative optimization of the two energy flow paths, the optimal transmission efficiency of the system is realized. The power switch device of the three-port bidirectional converter is reused, so that the volume and weight of the vehicle-mounted equipment are reduced, and the system cost is reduced. Meanwhile, by using the active adjustment and efficiency optimization mechanism among the multi-ports, the flexible distribution and bidirectional flow of energy among the three ports are realized, and the intelligent coordination ability and power supply continuity of the hybrid energy storage system are improved.

Description

Technical Field

[0001] This invention belongs to the field of wireless power transmission technology, and particularly relates to a three-port hybrid energy storage wireless power transmission system and its efficiency optimization control method. Background Technology

[0002] Wireless Power Transfer (WPT) breaks through the physical limitations of traditional wired power supply, providing devices with a flexible and efficient energy supply method. It avoids the risk of open flames caused by frequently plugging and unplugging wired interfaces during power use, driving innovation in energy utilization models. Against the backdrop of the rapid development of the electric vehicle industry, wireless power transfer technology, with its advantages of no physical contact, safety, and convenience, is gradually becoming an important development direction for electric vehicle energy replenishment. A three-port hybrid energy storage wireless power transfer system can simultaneously realize energy exchange between grid-side power supply, vehicle-side high-voltage battery energy storage, and vehicle-side low-voltage battery energy storage, supporting multiple operation modes such as static charging and energy feedback.

[0003] In electric vehicle applications, traditional unidirectional, single-port inductive wireless power transfer systems have limitations in energy dispatch flexibility and multimodal management, making it difficult to meet the requirements of efficient energy distribution in complex application environments. This leads to significant challenges in the interoperability of wireless power transfer systems. Therefore, studying the operating characteristics of three-port hybrid energy storage wireless power transfer systems under different compensation structures helps to broaden the system's multimodal operation.

[0004] However, existing three-port systems still face architectural and control bottlenecks. In terms of topology, to accommodate the power supply needs of the vehicle-side low-voltage battery, current technologies often require the addition of an independent active inverter circuit and compensation structure on the low-voltage side. This not only increases the system hardware size and cost but also wastes high-voltage side power device resources, making it difficult to meet the requirements of integrated and lightweight vehicle equipment. Furthermore, in terms of multi-variable control, the three-port hybrid energy storage wireless power transmission system relies on two core control variables: the phase shift angle of the grid-side converter and the phase shift angle of the three-port bidirectional converter, as well as the angle by which the fundamental AC voltage component of the three-port bidirectional converter leads the grid-side converter. These three variables are related to the converter's operating mode and the phase difference between the converter's output voltage and current under different energy transfer modes. If the threshold determination is flawed or sudden changes in operating conditions lead to variable mismatch, power transmission fluctuations and unstable mode switching are likely to occur. Additionally, regarding limitations in multi-port efficiency optimization, efficiency gaps can easily occur when switching between the three transmission modes during electric vehicle operation, making it difficult to achieve optimal overall energy efficiency across all operating conditions and multiple ports. This results in the electric vehicle being unable to autonomously adjust and achieve optimal efficiency control in each mode. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a three-port hybrid energy storage wireless power transfer system and its efficiency optimization control method. This invention can be used to integrate multiple load ports, realize converter multiplexing, and ensure the efficient and stable operation of the wireless power transfer system.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] This invention provides a three-port hybrid energy storage wireless power transmission system, including a grid-side port, a vehicle-side high-voltage battery port, and a vehicle-side low-voltage battery port; The grid-side port includes a DC power supply, a grid-side converter, a grid-side LCC compensation structure, and the primary coil of the first magnetic coupling mechanism connected in sequence. The vehicle-side high-voltage battery port includes a secondary coil of a first magnetic coupling mechanism, a vehicle-side high-voltage LCC compensation structure, a first AC terminal of a three-port bidirectional converter, and a vehicle-side high-voltage battery, which are connected in sequence; the second AC terminal of the three-port bidirectional converter is connected to the input terminal of the vehicle-side high-voltage LCC compensation structure. The vehicle-side low-voltage battery port includes a secondary coil of a second magnetic coupling mechanism, an S-shaped compensation structure, a rectifier, and a vehicle-side low-voltage battery connected in sequence; the primary coil of the second magnetic coupling mechanism is connected to the output terminal of the vehicle-side high-voltage LCL compensation structure. The network-side port and the vehicle-side high-voltage battery port form an LCC-LCC bilateral resonant topology, and the vehicle-side high-voltage battery port and the vehicle-side low-voltage battery port form an LCL-S series resonant topology. The LCC-LCC bilateral resonant topology and the LCL-S series resonant topology reuse the power switching devices of the three-port bidirectional converter to realize bidirectional energy flow between the grid side and the vehicle side high-voltage battery, and support multi-mode energy flow between the grid side and the vehicle side low-voltage battery, and between the vehicle side high-voltage battery and the vehicle side low-voltage battery; the vehicle side low-voltage battery port does not have an independent active inverter circuit.

[0008] In one embodiment, the system further includes a system control unit; the system control unit is signal-connected to the grid-side converter and the three-port bidirectional converter, respectively; the system control unit is configured to support three operating modes: Mode 1: When the electric vehicle is parked, the grid-side port simultaneously transmits electrical energy to the vehicle-side high-voltage battery port and the vehicle-side low-voltage battery port; Mode 2: When the electric vehicle is parked, the high-voltage battery port on the vehicle side feeds back electrical energy to the grid side port; Mode 3: When the electric vehicle is in motion, the grid-side converter is turned off, and only the high-voltage battery port on the vehicle side transmits electrical energy to the low-voltage battery port on the vehicle side.

[0009] In one implementation, the system control unit configures the energy transfer path for three operating modes as follows: In Mode 1, two energy transmission paths are formed: the grid-side port is connected to the vehicle-side high-voltage battery port via an LCC-LCC bilateral resonant topology and a three-port bidirectional converter; the vehicle-side high-voltage battery port is connected to the vehicle-side low-voltage battery port via an LCL-S series resonant topology. This enables independent closed-loop regulation of the charging power of the two paths. In mode 2, a reverse energy transmission path is formed from the vehicle-side high-voltage battery port to the grid-side port via a three-port bidirectional converter and an LCC-LCC bilateral resonant topology, thereby realizing grid-side energy feedback. In mode 3, all drive signals of the grid-side converter are cut off, the energy transmission path of the grid-side port is disconnected, and only the energy transmission path from the three-port bidirectional converter to the vehicle-side low-voltage battery port through the LCL-S series resonant topology is formed.

[0010] The present invention also provides an efficiency optimization control method for a three-port hybrid energy storage wireless power transmission system, applied to the aforementioned three-port hybrid energy storage wireless power transmission system, the method comprising the following steps: Step S1: Based on the system topology and transmission characteristics, determine the inner phase shift angle threshold for the grid-side converter and the three-port bidirectional converter to achieve zero-voltage turn-on operation; Step S2: Match the corresponding operating mode according to the operating status of the electric vehicle, establish the circuit mathematical model of each port, and determine the transmission efficiency function under the corresponding operating mode based on the phase relationship between the AC terminal voltage and current of the three-port bidirectional converter. Step S3: With the goal of maximizing transmission efficiency, solve for the extreme values ​​of the transmission efficiency function under each operating mode to obtain the optimal control parameters for each operating mode. Step S4: Based on the determined inner phase shift angle threshold and optimal control parameters, perform coordinated phase shift control on the grid-side converter and the three-port bidirectional converter to achieve zero-voltage turn-on operation of the power switching devices in the corresponding mode and maintain stable output power.

[0011] In one embodiment, step S1 includes: Step S11: Gradually change the inner phase shift angle of the grid-side converter and the inner phase shift angle of the three-port bidirectional converter with a set step size; Step S12: Real-time detection of the zero-crossing phase difference between the AC terminal voltage and current of the two converters, combined with the converter operating modes under different energy transmission directions, matching the range of inner phase shift angles that meet zero-voltage turn-on, and determining the inner phase shift angle thresholds under different energy transmission directions respectively.

[0012] In one embodiment, step S2 includes: Step S21: Based on the equivalent circuits of LCC-LCC bilateral resonant topology and LCL-S series resonant topology, obtain the circuit parameters of each port and establish a circuit mathematical model including the relationship between branch current and voltage. Step S22: Based on the circuit mathematical model, establish the active power expressions for the grid-side port and the vehicle-side high-voltage battery port for Mode 1 and Mode 2. Step S23: Based on the active power expression, using the phase difference and voltage gain of the AC terminal voltage of the three-port bidirectional converter relative to the AC terminal voltage of the grid-side converter as variables, construct the transmission efficiency function of the grid-side and vehicle-side high-voltage battery system under mode 1 and mode 2. Step S24: Based on the LCL-S series resonant topology, and taking the equivalent load of the vehicle-side low-voltage battery as a variable, construct the transmission efficiency function between the vehicle-side high-voltage battery port and the vehicle-side low-voltage battery port under mode 3. Step S25: Based on the transmission efficiency functions of the grid-side and vehicle-side high-voltage battery system under Mode 1 and Mode 2, and the transmission efficiency function of the vehicle-side high-voltage battery port and vehicle-side low-voltage battery port under Mode 3, determine the transmission efficiency function under the corresponding operating mode.

[0013] In one implementation, the transmission efficiency function of each operating mode satisfies the following relationship: , in, Let be the transmission efficiency function when the system is operating in mode 1. Let be the transmission efficiency function when the system is operating in mode 2. Let be the transmission efficiency function when the system is operating in mode 3. For Mode 1, the transmission efficiency function between the grid-side and vehicle-side high-voltage battery systems is given. This is the transmission efficiency function between the network-side and vehicle-side high-voltage battery systems in Mode 2. This is a function representing the transmission efficiency between the high-voltage battery port and the low-voltage battery port on the vehicle side. For the angular frequencies of the grid-side converter and the three-port bidirectional converter, For the mutual inductance between the grid-side and vehicle-side coils, This refers to the mutual inductance between the coils of the high-voltage battery and the low-voltage battery on the vehicle side. and Inductors and Reactance, and These are the internal resistances of the wire-side and vehicle-side coils, respectively. and These are the internal resistances of the coils for the high-voltage battery and the low-voltage battery on the vehicle side, respectively. and These are the inductor internal resistances of the LCC compensation structures on the grid side and vehicle side, respectively. This is the equivalent internal resistance of the low-voltage battery on the vehicle side, and , For voltage gain, This represents the effective value of the AC terminal voltage of the grid-side converter. This represents the effective value of the AC terminal voltage of the three-port bidirectional converter. The fundamental component of the AC voltage of the three-port bidirectional converter leads the phase difference of the grid-side converter.

[0014] In one implementation, step S3 includes: Step S31: For Mode 1 and Mode 2, establish optimization objective functions and constraints, with the goal of maximizing efficiency, for the transmission efficiency functions of the grid-side and vehicle-side high-voltage battery systems. and By taking the derivative and solving, we can obtain the phase difference and voltage gain of the fundamental component of the AC voltage of the three-port bidirectional converter leading the grid-side converter, which can be used as the optimal control parameters for mode 1 and mode 2. Step S32: For mode 3, optimize the transmission efficiency function between the vehicle-side high-voltage battery port and the vehicle-side low-voltage battery port with the goal of maximizing efficiency. The derivative is obtained by solving for the equivalent load of the low-voltage battery on the vehicle side, which is used as the optimal control parameter for mode 3.

[0015] In one implementation, the objective function and constraints are established as follows:

[0016] in, Indicates the maximum value. For transmission efficiency function, For voltage gain, Indicates constraints; when Corresponding to mode 1 and At that time, for the transmission efficiency function Differentiate to obtain the optimal voltage gain. The fundamental component of the AC voltage of the three-port bidirectional converter leads the phase difference of the grid-side converter. The expression is: , when Corresponding to mode 2 and At that time, for the transmission efficiency function Differentiate to obtain the optimal voltage gain. The fundamental component of the AC voltage of the three-port bidirectional converter leads the phase difference of the grid-side converter. The expression is: , When the transmission efficiency between the vehicle-side high-voltage battery and the vehicle-side low-voltage battery is optimal in Mode 3, the corresponding optimal equivalent load is: , in, This is the optimal equivalent load.

[0017] In one embodiment, step S4 includes: Step S41: Obtain the first target phase shift angle set corresponding to the current operating mode and the second target phase shift angle set corresponding to the operating mode to be switched into. Both sets are internal phase shift angle thresholds that satisfy zero-voltage turn-on. Step S42: Gradually adjust the inner phase angle of the grid-side converter, the inner phase angle of the three-port bidirectional converter, and the phase difference of the fundamental components of their AC voltages with a set step size, smoothly transitioning from the first target phase angle set to the second target phase angle set. During the transition, the zero-crossing phase difference of the AC terminal voltage and current of the two converters is detected in real time to ensure that the zero-voltage turn-on constraint condition is met. Step S43: After the inner phase angle is adjusted to the correct position and the system output power tends to stabilize, switch the on / off state of the corresponding energy transmission path to complete the seamless switching of the operating mode.

[0018] Beneficial effects of this invention:

[0019] 1. The low-voltage battery port on the vehicle side eliminates the need for a separate active inverter circuit, reusing the power switching devices of the same three-port bidirectional converter. Compared to multi-converter splicing solutions, this significantly reduces the number of devices and the size of the on-board equipment, making it suitable for space-constrained applications.

[0020] 2. By utilizing the multiplexed and independent bridge arms of the three-port bidirectional converter, independent closed-loop regulation of the high-voltage and low-voltage outputs is achieved; through the magnetic decoupling design of two sets of magnetic coupling mechanisms, cross-interference between the two links is eliminated, ensuring output stability under multiple load conditions.

[0021] 3. Supports three operating modes: in parked mode, the grid side simultaneously charges the high-voltage / low-voltage battery; in driving mode, the high-voltage battery feeds energy back to the grid side; and in driving mode, the grid-side link is turned off and the high-voltage battery continuously supplies power to the low-voltage battery. This covers all operating conditions—charging off, energy feedback, and driving—improving system integration and practicality.

[0022] 4. Both LCC-LCC and LCL-S topologies operate in a resonant state with low reactive power loss. By coordinating the adjustment of phase shift angle and phase difference through an extreme value optimization algorithm, zero-voltage turn-on of full-power devices can be achieved in all three modes, reducing switching losses and electromagnetic interference, and achieving optimal global efficiency.

[0023] 5. A phase-shift parameter gradual transition strategy is adopted to maintain the constraint of zero-voltage turn-on during the switching process; the transmission path is switched after the output power is stable, which effectively suppresses switching shock and device stress and extends the system life. Attached Figure Description

[0024] The accompanying drawings, as part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation of the invention. Obviously, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0025] Figure 1 A structural diagram of a three-port hybrid energy storage wireless power transmission system provided in an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the energy transmission paths for three modes of a three-port hybrid energy storage wireless power transmission system provided in one embodiment of the present invention, wherein... Figure 2 (a) is a schematic diagram of the energy transfer path in Mode 1. Figure 2 (b) is a schematic diagram of the energy transfer path in Mode 2. Figure 2 (c) is a schematic diagram of the energy transfer path in Mode 3;

[0027] Figure 3 This is an equivalent circuit for the transmission stage between the network-side port and the vehicle-side high-voltage battery port provided in one embodiment of the present invention;

[0028] Figure 4 This is an equivalent circuit for the transmission stage between the vehicle-side high-voltage battery port and the vehicle-side low-voltage battery port provided in one embodiment of the present invention;

[0029] Figure 5 This is a steady-state waveform diagram of voltage and current in Mode 1 provided in an embodiment of the present invention, wherein... Figure 5 Figure (a) shows the steady-state waveforms of the output voltage and current of the grid-side converter. Figure 5 Figure (b) shows the steady-state waveforms of the output voltage and current of the three-port bidirectional converter.

[0030] Figure 6 This is a waveform diagram of the efficiency of each port provided in one embodiment of the present invention, wherein... Figure 6 Figure (a) shows the efficiency waveform of the system operating in mode 1. Figure 6 Figure (b) shows the efficiency waveform of the system operating in mode 2. Figure 6 (c) is the efficiency waveform of the system running in mode 3;

[0031] Figure 1Reference numerals: 1. DC power supply; 2. Grid-side converter; 3. Grid-side LCC compensation structure; 4. First magnetic coupling mechanism; 5. Vehicle-side high-voltage LCC compensation structure; 6. Three-port bidirectional converter; 7. Vehicle-side high-voltage battery; 8. Vehicle-side high-voltage LCC compensation structure; 9. Second magnetic coupling mechanism; 10. S-shaped compensation structure; 11. Rectifier; 12. Vehicle-side low-voltage battery.

[0032] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0034] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings.

[0035] Terminology Explanation: In wireless power transfer (WPT) systems, the compensation structure is a core component. Its main function is to perform impedance matching and reactive power compensation, thereby reducing switching losses and improving the system's power factor and transmission efficiency. Based on the series and parallel combination of circuit elements (inductor L, capacitor C), common compensation topologies are defined as follows:

[0036] 1) S-type compensation structure: refers to the compensation capacitor being connected in series with the energy transfer coil.

[0037] 2) LCC compensation structure, which is a high-order composite compensation structure. Taking the transmitter LCC compensation as an example, it is defined as a composite network structure composed of an inductor, a series compensation capacitor and a parallel compensation capacitor.

[0038] 3) LCL compensation structure, which is a high-order compensation structure, is defined as: introducing additional compensation inductors and compensation capacitors into the circuit to form a double resonant structure.

[0039] 4) LCC-LCC bilateral resonant topology refers to a wireless power transmission topology in which both the primary and secondary sides are compensated by LCC.

[0040] 5) The LCL-S series resonant topology refers to a resonant network formed by cascading LCL compensation on one side and S compensation on the other side.

[0041] This embodiment provides a three-port hybrid energy storage wireless power transmission system for realizing multi-port collaborative wireless power transmission in electric vehicles, integrating high-voltage battery wireless charging and low-voltage auxiliary battery power supply design.

[0042] like Figure 1 As shown, the system includes a grid-side port, a vehicle-side high-voltage battery port, and a vehicle-side low-voltage battery port. The grid-side port includes a DC power supply 1, a grid-side converter 2, a grid-side LCC compensation structure 3, and the primary coil of a first magnetic coupling mechanism 4, connected in sequence. The vehicle-side high-voltage battery port includes the secondary coil of the first magnetic coupling mechanism 4, the vehicle-side high-voltage LCC compensation structure 5, the first AC terminal of a three-port bidirectional converter 6, and a vehicle-side high-voltage battery 7, connected in sequence. The second AC terminal of the three-port bidirectional converter 6 is connected to the input terminal of the vehicle-side high-voltage LCC compensation structure 8. The vehicle-side low-voltage battery port includes the secondary coil of a second magnetic coupling mechanism 9, an S-type compensation structure 10, a rectifier 11, and a vehicle-side low-voltage battery 12, connected in sequence. The primary coil of the second magnetic coupling mechanism 9 is connected to the output terminal of the vehicle-side high-voltage LCC compensation structure 8. The grid-side port and the vehicle-side high-voltage battery port form an LCC-LCC bilateral resonant topology, and the vehicle-side high-voltage battery port and the vehicle-side low-voltage battery port form an LCC-S series resonant topology. The LCC-LCC bilateral resonant topology and the LCL-S series resonant topology reuse the power switching devices of the three-port bidirectional converter to realize bidirectional energy flow between the grid side and the vehicle side high-voltage battery, and support multi-mode energy flow between the grid side and the vehicle side low-voltage battery, and between the vehicle side high-voltage battery and the vehicle side low-voltage battery; the vehicle side low-voltage battery port does not have an independent active inverter circuit.

[0043] Figure 1 middle , These are the power switches for the grid-side converter and the three-port bidirectional converter, respectively. and These are the primary and secondary coils of the first magnetic coupling mechanism 4, respectively. The inductance of the grid-side LCC compensation structure 3, The inductance of the LCC compensation structure 5 on the high-voltage side of the vehicle side. and For the capacitor of the grid-side LCC compensation structure 3, and The capacitor is the LCC compensation structure 5 on the high-voltage side of the vehicle. and The primary and secondary coils of the second magnetic coupling mechanism 9 The inductance of the LCL compensation structure 8 on the high-voltage side of the vehicle side. The capacitor is for the LCL compensation structure 8 on the high-voltage side of the vehicle. The capacitor is an S-type compensation structure 10. and These are the internal resistances of the wire-side and vehicle-side coils, respectively. The inductance of the LCL compensation structure 8 on the high-voltage side of the vehicle is shown. and These are the internal resistances of the coils for the high-voltage battery and the low-voltage battery on the vehicle side, respectively. and The inductor internal resistances are those of the grid-side LCC compensation structure and the high-voltage-side LCC compensation structure, respectively. This is the equivalent internal resistance of the low-voltage battery on the vehicle side, and , This represents the effective value of the AC terminal voltage of the grid-side converter. This represents the effective value of the AC terminal voltage of the three-port bidirectional converter. For the mutual inductance between the grid-side and vehicle-side coils, This refers to the mutual inductance between the coils of the high-voltage battery and the low-voltage battery on the vehicle side. This refers to the voltage at the DC terminal of the high-voltage battery on the vehicle side. This refers to the DC voltage of the low-voltage battery on the vehicle side. and These are voltage stabilizing capacitors for the DC terminals of the high-voltage battery and the low-voltage battery on the vehicle side.

[0044] In a preferred embodiment, the system includes a system control unit, which is signal-connected to the grid-side converter and the three-port bidirectional converter, respectively. The system control unit is configured to support three operating modes:

[0045] Mode 1: When the electric vehicle is parked, the grid-side port simultaneously transmits electrical energy to the vehicle-side high-voltage battery port and the vehicle-side low-voltage battery port;

[0046] Mode 2: When the electric vehicle is parked, the high-voltage battery port on the vehicle side feeds back electrical energy to the grid side port;

[0047] Mode 3: When the electric vehicle is in motion, the grid-side converter is turned off, and only the high-voltage battery port on the vehicle side transmits electrical energy to the low-voltage battery port on the vehicle side.

[0048] Furthermore, the system control unit configures the energy transfer paths for the three operating modes as follows:

[0049] In Mode 1, two energy transmission paths are formed: the grid-side port is connected to the vehicle-side high-voltage battery port via an LCC-LCC bilateral resonant topology and a three-port bidirectional converter; the vehicle-side high-voltage battery port is connected to the vehicle-side low-voltage battery port via an LCL-S series resonant topology. This enables independent closed-loop regulation of the charging power of the two paths.

[0050] In mode 2, a reverse energy transmission path is formed from the vehicle-side high-voltage battery port to the grid-side port via a three-port bidirectional converter and an LCC-LCC bilateral resonant topology, thereby realizing grid-side energy feedback.

[0051] In mode 3, all drive signals of the grid-side converter are cut off, the energy transmission path of the grid-side port is disconnected, and only the energy transmission path from the three-port bidirectional converter to the vehicle-side low-voltage battery port through the LCL-S series resonant topology is formed.

[0052] Reference Figure 2 As shown, the red arrows indicate the direction of energy flow. Among them, Figure 2 (a) is a schematic diagram of the energy transmission path in Mode 1, where the entire system participates in energy transmission; Figure 2 (b) is a schematic diagram of the energy transfer path in mode 2. The blurred part in the diagram is used to illustrate that when the system is running in mode 2, the low-voltage battery port on the vehicle side does not participate in the power transfer. Figure 2 (c) is a schematic diagram of the energy transmission path in mode 3. The blurred part in the figure is used to illustrate that when the system is running in mode 3, the grid-side port does not participate in power transmission.

[0053] Specifically, the DC power supply 1, the vehicle-side high-voltage battery 7, and the vehicle-side low-voltage battery 12 include components such as batteries and capacitors that can generate DC voltage. The DC power supply 1 is obtained from the grid voltage after rectification and other transformations, and it supplies power to the high-frequency inverter and commutation control circuit. The vehicle-side high-voltage battery 7 stores energy for the electric vehicle during mode 1 transmission, feeds energy back to the grid during mode 2 transmission, and outputs energy to the low-voltage battery during mode 3 transmission. The vehicle-side low-voltage battery 12 stores energy for the electric vehicle during mode 1 transmission and stores energy for the electric vehicle during mode 3 transmission. The grid-side converter 2 converts the DC voltage output from the DC power supply into AC voltage or rectifies the AC voltage received by the grid-side coil into DC voltage. The three-port bidirectional converter 6 rectifies the AC voltage received by the vehicle-side coil into DC voltage to charge the vehicle-side high-voltage battery 7 and transmits electrical energy to the vehicle-side high-voltage battery port compensation structure, or converts the DC voltage output from the high-voltage battery into AC voltage to feed back to the grid port or supply power to the low-voltage battery. The grid-side converter 2 and the three-port bidirectional converter 6 are inverters or rectifiers composed of power switching transistors. The primary coil of the first magnetic coupling mechanism 4... In Mode 1 transmission, it is used to transmit grid-side energy to the secondary coil of the first magnetic coupling mechanism 4. In mode 2 transmission, the secondary coil of the first magnetic coupling mechanism 4 used to receive the high-voltage battery port on the vehicle side Energy is emitted. The secondary coil of the first magnetic coupling mechanism 4... In mode 2 transmission, it is used to transmit energy from the vehicle-side high-voltage battery to the primary coil of the first magnetic coupling mechanism 4. The primary coil of the first magnetic coupling mechanism 4 used to receive the network-side port during mode 1 transmission. The emitted energy. The primary coil of the second magnetic coupling mechanism 9. In Mode 1 transmission, the secondary coil of the second magnetic coupling mechanism 9 is used to transmit grid-side energy through the three-port bidirectional converter 6 to the low-voltage battery port. The primary coil of the second magnetic coupling mechanism 9 at the high-voltage battery port on the vehicle side. In mode 3 transmission, the secondary coil of the second magnetic coupling mechanism 9, used to transmit energy from the high-voltage battery on the vehicle side to the low-voltage battery port via the three-port bidirectional converter 6, is... .

[0054] In one embodiment, an efficiency optimization control method for a three-port hybrid energy storage wireless power transmission system is proposed. Applied to the aforementioned three-port hybrid energy storage wireless power transmission system, the method includes the following steps:

[0055] Step S1: Based on the system topology and transmission characteristics, determine the inner phase shift threshold for the grid-side converter and the three-port bidirectional converter to achieve zero-voltage turn-on operation.

[0056] In this embodiment of the application, step S1 includes the following steps:

[0057] Step S11: Gradually change the inner phase shift angle of the grid-side converter and the inner phase shift angle of the three-port bidirectional converter with a set step size.

[0058] Step S12: Real-time detection of the zero-crossing phase difference between the AC terminal voltage and current of the two converters, combined with the converter operating modes under different energy transmission directions, matching the impedance angle range that satisfies zero-voltage turn-on, and determining the inner phase shift angle threshold under different energy transmission directions respectively.

[0059] Furthermore, the expression for the range of inner phase shift angles that satisfy zero-voltage turn-on is:

[0060]

[0061] in, This is the inner phase shift angle of the grid-side converter. This refers to the internal phase shift angle of the three-port bidirectional converter. and These are the impedance angles of the grid-side port and the vehicle-side high-voltage battery port, respectively.

[0062] Step S2: Match the corresponding operating mode according to the operating status of the electric vehicle, establish the circuit mathematical model of each port, and determine the transmission efficiency function under the corresponding operating mode based on the phase relationship between the AC terminal voltage and current of the three-port bidirectional converter.

[0063] In this embodiment of the application, step S2 includes the following steps:

[0064] Step S21: Based on the equivalent circuits of the LCC-LCC bilateral resonant topology and the LCL-S series resonant topology, obtain the circuit parameters of each port and establish a circuit mathematical model that includes the relationship between branch current and voltage.

[0065] Figure 3 The equivalent circuit for the transmission stage between the grid-side port and the vehicle-side high-voltage battery port is presented. The circuit adopts an LCC-LCC bilateral resonant topology. Based on the equivalent circuit of this system, the circuit parameters between each port are derived. Figure 4 The equivalent circuit for the transmission stage between the high-voltage battery port and the low-voltage battery port on the vehicle side is presented. The circuit adopts an LCL-S series resonant topology. Based on this system topology, the circuit parameters between each port are derived, and a circuit mathematical model containing the relationship between branch current and voltage is established.

[0066] To achieve resonance in the LCC-LCC resonant topology bidirectional wireless power transfer system between the grid-side port and the vehicle-side high-voltage battery port, the angular frequency ω of the grid-side converter and the three-port bidirectional converter, and the resonant network parameters, should satisfy the following:

[0067]

[0068] The expressions for each reactance are as follows: , , , , , , .

[0069] Taking the fundamental component of the AC voltage of the grid-side converter as the reference vector, denoted as... The fundamental component of the AC voltage in a three-port bidirectional converter is denoted as... Therefore, the relationship between the currents in each branch can be determined as follows:

[0070]

[0071] in, ; and The reactances of inductors L1 and L2 are respectively. and They are and The current in the branch, This refers to the current in the grid-side port coil. This refers to the current in the high-voltage battery port coil on the vehicle side. For imaginary units, For the mutual inductance between the grid-side and vehicle-side coils, The fundamental component of the AC voltage of the three-port bidirectional converter leads the phase difference of the grid-side converter.

[0072] Step S22: Based on the circuit mathematical model, establish the active power expressions for the grid-side port and the vehicle-side high-voltage battery port for Mode 1 and Mode 2.

[0073] Furthermore, the active power at the network-side port The expression is:

[0074]

[0075] Furthermore, the active power of the high-voltage battery port on the vehicle side The expression is:

[0076]

[0077] in, This refers to the active power at the network-side port. This refers to the active power at the high-voltage battery port on the vehicle side.

[0078] Step S23: Based on the active power expression, using the phase difference and voltage gain of the AC terminal voltage of the three-port bidirectional converter relative to the AC terminal voltage of the grid-side converter as variables, construct the transmission efficiency function of the grid-side and vehicle-side high-voltage battery system under Mode 1 and Mode 2.

[0079] Furthermore, voltage gain for:

[0080]

[0081] In Mode 1, the transmission efficiency of the high-voltage battery system between the grid side and the vehicle side... The expression is:

[0082]

[0083] Mode 2: High-voltage battery system transmission efficiency between the grid side and the vehicle side The expression is:

[0084]

[0085] When an electric vehicle is in Mode 1 static charging and Mode 2 static energy feedback, the positions of the grid-side port and the vehicle-side high-voltage battery port coils remain unchanged, therefore , Furthermore, the inductance and resistance of the compensation components do not change during system operation, therefore the voltage gain can be adjusted. and phase difference To optimize the system's transmission efficiency.

[0086] Step S24: Based on the LCL-S series resonant topology, and taking the equivalent load of the vehicle-side low-voltage battery as a variable, construct the transmission efficiency function between the vehicle-side high-voltage battery port and the vehicle-side low-voltage battery port under mode 3.

[0087] When the electric vehicle is operating in Mode 1 and Mode 2, the transmission efficiency between the high-voltage battery port and the low-voltage battery port on the vehicle side is... The expression is:

[0088]

[0089] in, This refers to the mutual inductance between the coils of the high-voltage battery and the low-voltage battery on the vehicle side. and These are the internal resistances of the coils for the high-voltage battery and the low-voltage battery on the vehicle side, respectively. This is the equivalent internal resistance of the low-voltage battery on the vehicle side, and .

[0090] Step S25: Based on the transmission efficiency functions of the grid-side and vehicle-side high-voltage battery system under Mode 1 and Mode 2, and the transmission efficiency function of the vehicle-side high-voltage battery port and vehicle-side low-voltage battery port under Mode 3, determine the transmission efficiency function under the corresponding operating mode.

[0091] Based on the electric vehicle's driving status, the transmission efficiency function expressions for the three operating modes are as follows:

[0092]

[0093] in, This is the transmission efficiency function when the system is operating in mode 1. This is the transmission efficiency function for the system operating in mode 2. This is the transmission efficiency function for the system operating in mode 3.

[0094] Step S3: With the goal of maximizing transmission efficiency, solve for the extreme values ​​of the transmission efficiency function under each operating mode to obtain the optimal control parameters for each operating mode.

[0095] In this embodiment of the application, step S3 includes the following steps:

[0096] Step S31: For Mode 1 and Mode 2, establish optimization objective functions and constraints, with the goal of maximizing efficiency, for the transmission efficiency functions of the grid-side and vehicle-side high-voltage battery systems. and The derivative is obtained, and the phase difference and voltage gain of the fundamental component of the AC voltage of the three-port bidirectional converter leading the grid-side converter are obtained, which are used as the optimal control parameters for Mode 1 and Mode 2.

[0097] Furthermore, the objective function and constraints are established as follows:

[0098]

[0099] in, Indicates the maximum value. For transmission efficiency function, For voltage gain, Indicates constraints;

[0100] when Corresponding to mode 1 and At that time, for the transmission efficiency function Differentiate to obtain the optimal voltage gain. The fundamental component of the AC voltage of the three-port bidirectional converter leads the phase difference of the grid-side converter. The expression is:

[0101]

[0102] when Corresponding to mode 2 and At that time, for the transmission efficiency function Differentiate to obtain the optimal voltage gain. The fundamental component of the AC voltage of the three-port bidirectional converter leads the phase difference of the grid-side converter. The expression is:

[0103]

[0104] With a fixed output power at the grid-side port and the vehicle-side high-voltage battery port, even if the circuit parameters of the grid-side and vehicle-side high-voltage batteries are different, the optimal voltage gain is consistent in both mode 1 and mode 2 transmission. The optimal efficiency is when the phase of the fundamental component of the AC voltage on the energy inflow side leads the phase of the fundamental component of the AC voltage on the energy outflow side by π / 2.

[0105] Step S32: For mode 3, optimize the transmission efficiency function between the vehicle-side high-voltage battery port and the vehicle-side low-voltage battery port with the goal of maximizing efficiency. The derivative is obtained by solving for the equivalent load of the low-voltage battery on the vehicle side, which is used as the optimal control parameter for mode 3.

[0106] Furthermore, in Mode 3, when the transmission efficiency between the vehicle-side high-voltage battery and the vehicle-side low-voltage battery is optimal, the corresponding optimal equivalent load is:

[0107]

[0108] in, This is the optimal equivalent load.

[0109] Step S4: Based on the determined inner phase shift angle threshold and optimal control parameters, perform coordinated phase shift control on the grid-side converter and the three-port bidirectional converter to achieve zero-voltage turn-on operation of the power switching devices in the corresponding mode and maintain stable output power.

[0110] Specifically, the zero-voltage turn-on phase shift angle threshold of the grid-side converter and the three-port bidirectional converter, determined by the transmission direction in step S1, serves as the constraint boundary, and the optimal control parameters obtained in step S3 are used as the adjustment benchmark. These optimal control parameters include the optimal equivalent load from the vehicle-side high-voltage battery to the vehicle-side low-voltage battery, and the optimal phase difference and voltage gain corresponding to the grid-side and vehicle-side high-voltage batteries. Based on this, multi-variable collaborative phase-shift closed-loop control is implemented on the grid-side converter and the three-port bidirectional converter, ensuring that the equivalent impedance angle of the converter ports always meets the zero-voltage switching condition in real time, stabilizing the output power of each port, and effectively reducing current surges and power oscillations during mode switching.

[0111] In this embodiment of the application, step S4 includes the following steps:

[0112] Step S41: Obtain the first target phase shift angle set corresponding to the current operating mode and the second target phase shift angle set corresponding to the operating mode to be switched into. Both sets are internal phase shift angle thresholds that meet the constraint conditions of zero voltage turn-on.

[0113] Specifically, a pre-determined multi-mode phase-shift constraint set is retrieved and matched against the current operating condition boundary. The system controller locally stores a set of phase-shift parameters for three operating modes. All parameters in the set have been determined through step S1, including the phase-shift angle within the grid-side converter. Three-port bidirectional converter internal phase shift angle The fundamental component of the AC voltage in the three-port bidirectional converter leads the phase difference of the grid-side converter. Impedance angle of the network-side port and the impedance angle of the high-voltage battery port on the vehicle side All parameters satisfy the constraints of the converter's zero-voltage turn-on condition. Identify the vehicle's real-time operating condition: Read the corresponding first target phase shift angle set [ , , ]; Receive upper-level energy scheduling instructions, determine the target operating mode to be switched to, and retrieve the set of second target phase shift angles specific to that mode. , , ]; Retrieve the optimal control benchmarks for the corresponding modes obtained in step S3: Mode 1 is the most efficient; Mode 2 is the most efficient; Mode 3 is the most efficient, corresponding to the optimal equivalent load. , which serves as the setpoint for closed-loop regulation.

[0114] Step S42: Gradually adjust the inner phase shift angle of the grid-side converter, the inner phase shift angle of the three-port bidirectional converter, and the phase difference of the fundamental components of their AC voltages with a set step size. Smoothly transition from the first target phase shift angle set to the second target phase shift angle set. During the transition, detect the zero-crossing phase difference of the AC terminal voltage and current of the two converters in real time to ensure that the zero-voltage turn-on constraint is met.

[0115] Specifically, three core control variables are adjusted synchronously and gradually using constant micro-steps: the phase shift angle of the full-bridge network side. Three-port bidirectional inward phase shift The three-port AC voltage leads the grid-side AC voltage phase difference. This system achieves a smooth transition of control quantities from the first set of target parameters to the second set, with closed-loop monitoring of the soft-switching status throughout the process: real-time sampling of the AC output voltage and high-frequency current waveforms of the grid-side converter and the three-port bidirectional converter; capturing the zero-crossing points of voltage and current through a hardware zero-crossing detection circuit; and calculating the current port equivalent impedance angle using a digital controller. The real-time impedance angle is compared with the ZVS allowable impedance angle range determined in step S1. If the current impedance angle is within the safe range, it is continuously updated with a fixed step size. If the impedance angle exceeds the ZVS threshold boundary, the adjustment step size is immediately reduced to 0.1°, large-amplitude parameter adjustments are paused, and gradual adjustment resumes after the impedance angle falls back to the soft-switching range. Voltage gain is simultaneously verified during the adjustment process. Equivalent load on the low-voltage side of the vehicle In step S3, the fundamental AC voltage component of the three-port bidirectional converter, which achieves optimal transmission efficiency from the grid-side to the vehicle-side high-voltage battery, is determined by real-time fine-tuning of the phase shift angle. This ensures that the fundamental component leads the phase difference and voltage gain of the grid-side converter, preventing the system operating point from deviating from the optimal efficiency range during adjustment. Taking the switch from mode 1 to mode 3 as an example: the three-port bidirectional phase shift angle is gradually increased. Reduce the phase shift angle of the grid-side converter Synchronous correction of the phase difference between the three-port AC voltage and the grid-side AC voltage. Throughout the process, the phase shift angle of the grid-side converter is guaranteed to meet ZVS.

[0116] Step S43: After the inner phase angle is adjusted to the correct position and the system output power tends to stabilize, switch the on / off state of the corresponding energy transmission path to complete the seamless switching of the operating mode.

[0117] Seamless switching of operating modes can suppress power fluctuations and current surges during the switching process.

[0118] Figure 5 The images show the steady-state waveforms of voltage and current in Mode 1, as well as the steady-state waveforms of voltage and current output from the grid-side converter and the three-port bidirectional converter under the three-phase-shift modulation strategy. The angle is . Figure 5 (a) shows the steady-state waveforms of the output voltage and current of the grid-side converter. As can be seen from the magnified details, the phase of the grid-side resonant current leads the corresponding bridge arm square wave voltage, and the grid-side power device achieves ZVS. Figure 5 Figure (b) shows the steady-state waveforms of the output voltage and current of the three-port bidirectional converter. As can be seen from the magnified details, the current of the three-port bidirectional converter leads the voltage, achieving zero-voltage switching (ZVS) and reducing switching losses. The situation in mode 2 is similar to that in mode 1.

[0119] Figure 6 The waveforms show the efficiency of each port. Figure 6 Figure (a) shows the efficiency waveform of the system operating in mode 1, with the system frequency set to 85kHz and the mutual inductance between the grid-side and vehicle-side coils. , resistance , ; , Internal resistance of the wire-side and vehicle-side coils The inductance of the LCC compensation structure on the grid side and vehicle side high voltage side .when The closer the system's efficiency is to zero, the lower its energy transfer efficiency becomes. The closer the value is to 1, the higher the energy transfer efficiency of the system. Figure 6 (b) is the efficiency waveform of the system operating in mode 2. Due to the selection of set parameters, the transmission efficiency between the grid-side and vehicle-side high-voltage battery system in mode 1 is different. The diagram is similar, when The closer the efficiency is to 0, the lower the energy transfer efficiency of the system. The closer the value is to -1, the higher the energy transfer efficiency of the system. Figure 6 (c) shows the efficiency waveform of the system operating in mode 3. The system frequency is set to 85kHz, and the mutual inductance between the vehicle-side high-voltage battery and the vehicle-side low-voltage battery coils is... The internal resistance of the coils of the high-voltage battery and the low-voltage battery on the vehicle side The equivalent internal resistance of the low-voltage battery on the vehicle side At this time, the system's energy transfer efficiency is at its maximum.

[0120] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A three-port hybrid energy storage wireless power transmission system, characterized in that: This includes the grid-side port, the vehicle-side high-voltage battery port, and the vehicle-side low-voltage battery port; The grid-side port includes a DC power supply, a grid-side converter, a grid-side LCC compensation structure, and the primary coil of the first magnetic coupling mechanism connected in sequence. The vehicle-side high-voltage battery port includes a secondary coil of a first magnetic coupling mechanism, a vehicle-side high-voltage LCC compensation structure, a first AC terminal of a three-port bidirectional converter, and a vehicle-side high-voltage battery, which are connected in sequence; the second AC terminal of the three-port bidirectional converter is connected to the input terminal of the vehicle-side high-voltage LCC compensation structure. The vehicle-side low-voltage battery port includes a secondary coil of a second magnetic coupling mechanism, an S-shaped compensation structure, a rectifier, and a vehicle-side low-voltage battery connected in sequence; the primary coil of the second magnetic coupling mechanism is connected to the output terminal of the vehicle-side high-voltage LCL compensation structure. The network-side port and the vehicle-side high-voltage battery port form an LCC-LCC bilateral resonant topology, and the vehicle-side high-voltage battery port and the vehicle-side low-voltage battery port form an LCL-S series resonant topology. The LCC-LCC bilateral resonant topology and the LCL-S series resonant topology reuse the power switching devices of the three-port bidirectional converter to realize bidirectional energy flow between the grid side and the vehicle side high-voltage battery, and support multi-mode energy flow between the grid side and the vehicle side low-voltage battery, and between the vehicle side high-voltage battery and the vehicle side low-voltage battery; the vehicle side low-voltage battery port does not have an independent active inverter circuit. The three-port bidirectional converter includes a first bridge arm and a second bridge arm. The first AC terminal is a differential AC terminal between the midpoint of the first bridge arm and the midpoint of the second bridge arm. The second AC terminal is an AC terminal led out from the midpoint of the second bridge arm. The power switching device of the second bridge arm also constitutes a common switching device for the first AC terminal and the second AC terminal. The system also includes a system control unit; the system control unit is connected to the grid-side converter and the three-port bidirectional converter respectively; the system control unit is configured to support three operating modes: Mode 1: When the electric vehicle is parked, the grid-side port simultaneously transmits electrical energy to the vehicle-side high-voltage battery port and the vehicle-side low-voltage battery port; Mode 2: When the electric vehicle is parked, the high-voltage battery port on the vehicle side feeds back electrical energy to the grid side port; Mode 3: When the electric vehicle is in motion, the grid-side converter is turned off, and only the high-voltage battery port on the vehicle side transmits electrical energy to the low-voltage battery port on the vehicle side.

2. The three-port hybrid energy storage wireless power transmission system according to claim 1, characterized in that: The system control unit is configured with the following energy transfer paths for the three operating modes: In Mode 1, two energy transmission paths are formed: the grid-side port is connected to the vehicle-side high-voltage battery port via an LCC-LCC bilateral resonant topology and a three-port bidirectional converter; the vehicle-side high-voltage battery port is connected to the vehicle-side low-voltage battery port via an LCL-S series resonant topology. This enables independent closed-loop regulation of the charging power of the two paths. In mode 2, a reverse energy transmission path is formed from the vehicle-side high-voltage battery port to the grid-side port via a three-port bidirectional converter and an LCC-LCC bilateral resonant topology, thereby realizing grid-side energy feedback. In mode 3, all drive signals of the grid-side converter are cut off, the energy transmission path of the grid-side port is disconnected, and only the energy transmission path from the three-port bidirectional converter to the vehicle-side low-voltage battery port through the LCL-S series resonant topology is formed.

3. An efficiency optimization control method for a three-port hybrid energy storage wireless power transmission system, characterized in that: The method, applied to the three-port hybrid energy storage wireless power transmission system according to any one of claims 1 to 2, comprises the following steps: Step S1: Based on the system topology and transmission characteristics, determine the inner phase shift angle threshold for the grid-side converter and the three-port bidirectional converter to achieve zero-voltage turn-on operation; Step S2: Match the corresponding operating mode according to the operating status of the electric vehicle, establish the circuit mathematical model of each port, and determine the transmission efficiency function under the corresponding operating mode based on the phase relationship between the AC terminal voltage and current of the three-port bidirectional converter. Step S3: With the goal of maximizing transmission efficiency, solve for the extreme values ​​of the transmission efficiency function under each operating mode to obtain the optimal control parameters for each operating mode. The transmission efficiency function for each operating mode satisfies the following relationship: , in, Let be the transmission efficiency function when the system is operating in mode 1. Let be the transmission efficiency function when the system is operating in mode 2. Let be the transmission efficiency function when the system is operating in mode 3. For Mode 1, the transmission efficiency function between the grid-side and vehicle-side high-voltage battery systems is given. This is the transmission efficiency function between the network-side and vehicle-side high-voltage battery systems in Mode 2. This is a function representing the transmission efficiency between the high-voltage battery port and the low-voltage battery port on the vehicle side. For the angular frequencies of the grid-side converter and the three-port bidirectional converter, For the mutual inductance between the grid-side and vehicle-side coils, This refers to the mutual inductance between the coils of the high-voltage battery and the low-voltage battery on the vehicle side. and Inductors and Reactance, and These are the internal resistances of the wire-side and vehicle-side coils, respectively. and These are the internal resistances of the coils for the high-voltage battery and the low-voltage battery on the vehicle side, respectively. and These are the inductor internal resistances of the LCC compensation structures on the grid side and vehicle side, respectively. This is the equivalent internal resistance of the low-voltage battery on the vehicle side, and , For voltage gain, This represents the effective value of the AC terminal voltage of the grid-side converter. This represents the effective value of the AC terminal voltage of the three-port bidirectional converter. The fundamental component of the AC voltage in the three-port bidirectional converter leads the phase difference of the grid-side converter. Step S4: Based on the determined inner phase shift angle threshold and optimal control parameters, perform coordinated phase shift control on the grid-side converter and the three-port bidirectional converter to achieve zero-voltage turn-on operation of the power switching devices in the corresponding mode and maintain stable output power.

4. The efficiency optimization control method for a three-port hybrid energy storage wireless power transmission system according to claim 3, characterized in that: Step S1 includes: Step S11: Gradually change the inner phase shift angle of the grid-side converter and the inner phase shift angle of the three-port bidirectional converter with a set step size; Step S12: Real-time detection of the zero-crossing phase difference between the AC terminal voltage and current of the two converters, combined with the converter operating modes under different energy transmission directions, matching the impedance angle range that satisfies the zero-voltage turn-on condition, and determining the inner phase shift angle threshold under different energy transmission directions respectively.

5. The efficiency optimization control method for a three-port hybrid energy storage wireless power transmission system according to claim 4, characterized in that: Step S2 includes: Step S21: Based on the equivalent circuits of LCC-LCC bilateral resonant topology and LCL-S series resonant topology, obtain the circuit parameters of each port and establish a circuit mathematical model including the relationship between branch current and voltage. Step S22: Based on the circuit mathematical model, establish the active power expressions for the grid-side port and the vehicle-side high-voltage battery port for Mode 1 and Mode 2. Step S23: Based on the active power expression, using the phase difference and voltage gain of the AC terminal voltage of the three-port bidirectional converter relative to the AC terminal voltage of the grid-side converter as variables, construct the transmission efficiency function of the grid-side and vehicle-side high-voltage battery system under mode 1 and mode 2. Step S24: Based on the LCL-S series resonant topology, and taking the equivalent load of the vehicle-side low-voltage battery as a variable, construct the transmission efficiency function between the vehicle-side high-voltage battery port and the vehicle-side low-voltage battery port under mode 3. Step S25: Based on the transmission efficiency functions of the grid-side and vehicle-side high-voltage battery system under Mode 1 and Mode 2, and the transmission efficiency function of the vehicle-side high-voltage battery port and vehicle-side low-voltage battery port under Mode 3, determine the transmission efficiency function under the corresponding operating mode.

6. The efficiency optimization control method for a three-port hybrid energy storage wireless power transmission system according to claim 5, characterized in that: Step S3 includes: Step S31: For Mode 1 and Mode 2, establish optimization objective functions and constraints, with the goal of maximizing efficiency, for the transmission efficiency functions of the grid-side and vehicle-side high-voltage battery systems. and By taking the derivative and solving, we can obtain the phase difference and voltage gain of the fundamental component of the AC voltage of the three-port bidirectional converter leading the grid-side converter, which can be used as the optimal control parameters for mode 1 and mode 2. Step S32: For mode 3, optimize the transmission efficiency function between the vehicle-side high-voltage battery port and the vehicle-side low-voltage battery port with the goal of maximizing efficiency. The derivative is obtained by solving for the equivalent load of the low-voltage battery on the vehicle side, which is used as the optimal control parameter for mode 3.

7. The efficiency optimization control method for a three-port hybrid energy storage wireless power transmission system according to claim 6, characterized in that: The objective function and constraints are defined as follows: ， in, Indicates the maximum value. For transmission efficiency function, For voltage gain, Indicates constraints; when Corresponding to mode 1 and At that time, for the transmission efficiency function Differentiate to obtain the optimal voltage gain. The fundamental component of the AC voltage of the three-port bidirectional converter leads the phase difference of the grid-side converter. The expression is: , when Corresponding to mode 2 and At that time, for the transmission efficiency function Differentiate to obtain the optimal voltage gain. The fundamental component of the AC voltage of the three-port bidirectional converter leads the phase difference of the grid-side converter. The expression is: , When the transmission efficiency between the vehicle-side high-voltage battery and the vehicle-side low-voltage battery is optimal in Mode 3, the corresponding optimal equivalent load is: , in, This is the optimal equivalent load.

8. The efficiency optimization control method for a three-port hybrid energy storage wireless power transmission system according to claim 3, characterized in that: Step S4 includes: Step S41: Obtain the first target phase shift angle set corresponding to the current operating mode and the second target phase shift angle set corresponding to the operating mode to be switched into. Both sets are internal phase shift angle thresholds that meet the zero-voltage turn-on condition. Step S42: Gradually adjust the inner phase shift angle of the grid-side converter, the inner phase shift angle of the three-port bidirectional converter, and the phase difference between the fundamental components of their AC voltages using a set step size. Smoothly transition from the first target phase shift angle set to the second target phase shift angle set. During the transition, the zero-crossing phase difference between the AC terminal voltages and currents of the two converters is detected in real time, and the current equivalent impedance angle of the port is calculated. If the current impedance angle is within the allowable impedance angle range for zero-voltage turn-on, it is continuously updated with a fixed step size. If the current impedance angle exceeds the zero-voltage turn-on threshold boundary, the adjustment step size is reduced to 0.1° and large-amplitude parameter adjustments are paused. Gradual adjustment is resumed after the impedance angle falls back to the zero-voltage turn-on range. The voltage gain is checked synchronously during the adjustment process. Equivalent load on the low-voltage side of the vehicle Ensure that the zero-voltage turn-on constraint is met; Step S43: After the inner phase angle is adjusted to the correct position and the system output power tends to stabilize, switch the on / off state of the corresponding energy transmission path to complete the seamless switching of the operating mode.

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