Electric vehicle wireless charging system based on adaptive impedance matching and control method

Abstract

The application discloses a kind of wireless charging system and control method of electric vehicle based on adaptive impedance matching, belong to wireless electric energy transmission technical field.For the problem that existing wireless charging system efficiency sharply declines when coupling coefficient changes, the application proposes a kind of comprehensive solution combining bilateral LCC compensation topology, anti-offset coupling mechanism and optimized variable step size disturbance observation method.The system establishes bilateral LCC impedance model by using double-tube Buck-Boost circuit as impedance transformer, and adopts an adaptive algorithm associated with step size and operating point gradient to dynamically track the maximum power point of the system.The application can quickly and adaptively complete impedance matching when load fluctuates or coil is offset, significantly improve the dynamic response speed, steady accuracy and overall transmission efficiency of the system, effectively solve the problem of low charging efficiency caused by parking position deviation of electric vehicle.

Description

Technical Field

[0001] This invention relates to the fields of power electronics and wireless power transmission technology, and in particular to a wireless charging system suitable for electric vehicles. Specifically, it is a system based on a bilateral LCC resonant compensation topology, integrating a dual-tube Buck-Boost impedance matching circuit on the receiving side, and combining an adaptive control algorithm to achieve efficient and stable charging, as well as a system and control method. Background Technology

[0002] With the rapid development of the electric vehicle industry, convenient and safe wireless charging technology has become a research hotspot. Magnetic-coupled resonant wireless power transfer (WPT) technology, due to its advantages such as being contactless and eliminating plugging and pulling wear, is considered an important future development direction for electric vehicle charging. However, in practical applications, due to the uncertainty of parking positions, there is often a horizontal or vertical offset between the transmitting and receiving coils, causing a change in the coupling coefficient between them. This change can lead to system impedance mismatch, resulting in a significant decrease in transmission efficiency, and in severe cases, even failure to function properly.

[0003] Currently, common compensation topologies for static wireless charging systems for electric vehicles include SS-type, LCC-S-type, and bilateral LCC-type. Among these, the SS-type topology has a simple structure, but its output characteristics are greatly affected by load and mutual inductance, and its resistance to offset is weak. The LCC-S-type topology can achieve constant current output within a certain range, but it is sensitive to parameter changes and has limited dynamic matching capabilities. The bilateral LCC topology, due to its symmetrical compensation structure on the primary and secondary sides, possesses good constant current / constant voltage output characteristics, high degrees of freedom, and robustness to parameter changes, making it more suitable as a research subject for wireless charging systems for electric vehicles. However, existing research mainly focuses on parameter optimization and static characteristic analysis of the bilateral LCC topology; research on its efficient and stable operation under dynamic offset conditions, especially how to adjust the system in real time to cope with changes in the coupling coefficient, is still insufficient.

[0004] In impedance matching, existing technologies mainly include passive matching networks and active matching circuits. Passive networks have fixed parameters and cannot adapt to dynamic changes. Active matching typically uses DC-DC converters (such as Buck, Boost, and Buck-Boost circuits) to regulate the equivalent load, but their control strategies often employ the traditional perturbation and observation (P&O) method or its improved algorithms. Traditional P&O algorithms suffer from slow dynamic response, large oscillations near the maximum power point, and susceptibility to noise interference. Although some research has attempted to improve these algorithms by introducing variable step size or fuzzy logic, the balance between convergence speed and steady-state accuracy remains unresolved when applied to high-order, nonlinear systems like two-sided LCCs.

[0005] More importantly, existing solutions often separate control methods from hardware structures, resulting in insufficient overall integrity and feasibility of the solutions. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a wireless charging control method and system for electric vehicles based on a bilateral LCC topology and adaptive impedance matching. This invention combines a bilateral LCC resonant compensation network with excellent output characteristics, a coupling coil design with strong anti-offset capability, and a novel optimized variable step-size perturbation observation method. This achieves rapid and accurate tracking of the system's maximum power transmission point under dynamically changing coupling coefficients, thereby significantly improving charging efficiency and system stability.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A wireless charging system for electric vehicles based on a bilateral LCC topology and adaptive impedance matching, characterized in that the system comprises:

[0009] Inverter modules are used to convert DC power to AC power;

[0010] The primary-side resonant compensation network is connected to the inverter module and is used for resonant compensation and output characteristic adjustment.

[0011] The primary-side transmitting coil and the secondary-side receiving coil form a magnetic coupling mechanism, which is connected to the primary-side resonant compensation network to resist offset.

[0012] A secondary-side resonant compensation network, connected to the magnetic coupling mechanism, is used for resonant compensation and output characteristic adjustment.

[0013] A rectifier module, coupled to the secondary receiving coil, is used to convert the induced high-frequency alternating current into direct current.

[0014] The voltage regulation and filtering module is connected to the output terminal of the rectifier module. It is used to filter and smooth the rectified DC power to output a stable DC voltage, which is then applied to the load.

[0015] The adaptive impedance matching module calculates the optimal duty cycle in real time based on the sampled system output power.

[0016] The controller module, employing a dual-transistor Buck-Boost circuit topology, is connected between the output of the rectifier module and the voltage regulator / filter module, and is also connected to the adaptive impedance matching module. It is used to control the duty cycle of the switching transistors in the adaptive impedance matching network based on the optimal duty cycle calculated by the adaptive impedance matching module. This serves as the actuator of the adaptive impedance matching module, enabling adaptive impedance matching and maximum power transfer efficiency tracking under varying coupling coefficient conditions.

[0017] In a first aspect, the present invention provides a wireless charging control method for electric vehicles based on a bilateral LCC topology and adaptive impedance matching, comprising the following steps:

[0018] Step S1: Establish the equivalent impedance model of the wireless power transmission system based on the bilateral LCC resonant compensation network, and determine the equivalent output impedance characteristic function of the system;

[0019] Step S2: Based on the topology parameters of the bilateral LCC resonant compensation network, the structural parameters of the coupling coil, and the rated operating parameters of the system, determine the initial duty cycle of the dual-tube Buck-Boost impedance matching circuit connected to the rectifier output terminal. According to the impedance characteristic function, the impedance matching is achieved by adjusting the duty cycle.

[0020] Step S3: The duty cycle of the dual-tube Buck-Boost circuit is dynamically optimized by using an optimized variable step size perturbation observation method. The equivalent impedance of the system is changed by continuously adjusting the duty cycle. The optimal impedance is calculated based on the impedance characteristic function, thereby achieving maximum power transfer efficiency tracking of the system under varying coupling coefficient conditions.

[0021] Furthermore, in step S1, by establishing the equivalent impedance model of the bilateral LCC resonant compensation network, the equivalent output impedance function Z of the system viewed from the magnetic coupling side towards the load is determined. S, Its expression is:

[0022]

[0023] The primary circuit, mapped by the circuit formula, is Z. R The mutual inductance M between the coupled coils is expressed as:

[0024]

[0025] Finally, the equivalent output impedance function Z from the inverter output side to the load is obtained. S (jw,D), its expression is:

[0026]

[0027] Where Lf1 For primary-side compensating inductance; C f1 For compensation capacitor; L f2 For secondary-side compensation inductance; C f2 L1 is the compensation capacitor; C1 is the primary inductance; W is the primary series capacitor; L2 is the system operating angular frequency; L1 and L2 are the primary and secondary coil inductances, respectively; C1 and C2 are the primary series compensation capacitor and the secondary series capacitor, respectively. eq (D) is the equivalent load impedance including the subsequent impedance matching network; D is the duty cycle of the switching transistor in the impedance matching network; w is the system operating angular frequency.

[0028] The dual-tube Buck-Boost impedance matching network is connected between the output of the rectifier module and the load. By adjusting the duty cycle of its switching transistors, the equivalent load impedance seen from the secondary-side LCC compensation network is changed.

[0029] Furthermore, the equivalent load impedance Z eq (D) The specific expression is:

[0030]

[0031] Where R L is the DC load resistor, and D is the duty cycle of the dual-transistor Buck-Boost circuit.

[0032] Furthermore, in step S2, the impedance adjustment function F(D)=Z of the adaptive impedance matching module is defined. eq (D). Based on the equivalent output impedance function and the system's rated operating point parameters, the initial duty cycle D is calculated. o This makes Z S (jw,D) satisfies or is close to the impedance matching condition under the rated coupling coefficient.

[0033] Furthermore, the total equivalent output impedance of the system after adaptive adjustment is Z. S (jw,D), the active power P transmitted by the system to the load. o The relationship with duty cycle D is as follows:

[0034]

[0035] Among them, V inv R is the fundamental effective value of the inverter output voltage. e [] indicates taking the real part of a complex number.

[0036] Furthermore, in step S3, the specific steps of the optimized variable step size perturbation observation method include:

[0037] Step S3-1: Obtain the system duty cycle D(k-1) at time k-1, and the system output power P at times k, k-1, and k-2. o (k), P o (k-1), P o (k-2);

[0038] Step S3-2: Calculate the change in system output power ΔP between adjacent time points. o (k)= P o (k)- P o (k-1) and △P o (k-1)= P o (k-1)- P o (k-2), and calculate △P o The absolute value of (k) ΔP o (k-1);

[0039] Step S3-3: Determine if the system has entered a steady state: If ΔP o (k-1) is less than the preset steady-state threshold. If the condition is met, the state is considered steady, the current adjustment period ends, and D(k) = D(k-1) is maintained; otherwise, proceed to step S3-4.

[0040] Step S3-4: Determine the trend of system operating point changes and update the duty cycle:

[0041] If △P o (k)·△P o (k-1)≥0, or △P o (k)·△P o (k-1)<0 and △P o If (k-1) < 0, then the operating point is determined to be moving towards the maximum power point, and the duty cycle is increased by an adaptive step size, the expression of which is:

[0042]

[0043] in, This is the step size scaling factor;

[0044] Otherwise, if △P o (k)·△P o (k-1)<0 and △P o (k-1)>0, and ,in To determine the threshold, it is determined that the operating point may have already exceeded the maximum power point, and the duty cycle is reduced by an adaptive step size:

[0045]

[0046] Otherwise, keep the duty cycle unchanged: D(k) = D(k-1).

[0047] Furthermore, the optimization objective of the optimized variable step-size perturbation observation method is to iteratively update the duty cycle D so that the real part Re[Z] of the system's equivalent output impedance is equal to the value of the real part Re[Z]. s [jw,D] approaches the characteristic source impedance R of the system. S That is, satisfying the maximum power transfer condition Re[Z] s [(jw,D)]= R S Thus achieving the system output power P o Maximize tracking of (k).

[0048] Furthermore, the bilateral LCC resonant compensation network consists of a primary-side LCC compensation circuit and a secondary-side LCC compensation circuit, and its parameters satisfy the system resonance condition, the expression of which is:

[0049]

[0050] Among them, L f1 For primary-side compensating inductance; C f1 For compensation capacitor; L f2 For secondary-side compensation inductance; C f2 C1 is the compensation capacitor; C2 is the primary inductor; C1 is the primary series capacitor; C2 is the secondary series capacitor; w is the system operating angular frequency; and L2 is the secondary inductor.

[0051] Furthermore, the primary-side transmitting coil and the secondary-side receiving coil are DD-type coils or a three-coil structure, and their mutual inductance M is horizontally offset. Within the range, satisfy:

[0052]

[0053] Where M0 is the mutual inductance value during alignment. Let f be the offset effect function. min To achieve the minimum coupling retention rate, a relatively stable coupling coefficient is maintained within a preset offset range.

[0054] Furthermore, the controller module calculates the real-time power by sampling the output voltage and output current of the rectifier module, and dynamically adjusts the duty cycle D of the PWM signal output to the impedance matching network according to the logic of the optimized variable step size perturbation observation method.

[0055] Compared with the prior art, the beneficial effects of the present invention are:

[0056] Dynamic impedance matching is achieved. By introducing an adaptive impedance matching module and adopting an optimized variable step size perturbation observation method, the system can automatically adjust its operating state when the coupling coefficient changes, thus maintaining high power transmission efficiency.

[0057] The overall system performance has been improved. By combining the stable output characteristics of the bilateral LCC resonant compensation network with adaptive matching control, the dynamic response and steady-state accuracy of the wireless charging system under offset conditions have been effectively improved. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the module connection of the wireless charging system provided in an embodiment of the present invention;

[0059] Figure 2 This is a flowchart of a wireless charging control method for electric vehicles based on bilateral LCC topology and adaptive impedance matching provided in an embodiment of the present invention.

[0060] Figure 3 These are schematic diagrams of the bilateral LCC resonant compensation network topology and the dual-tube Buck-Boost circuit provided in embodiments of the present invention.

[0061] Figure 4 This is a flowchart of the optimized variable step size perturbation and observation method (ASS-P&O) provided in an embodiment of the present invention. Detailed Implementation

[0062] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0063] This invention provides a wireless charging system for electric vehicles based on a bilateral LCC topology and adaptive impedance matching for implementing the aforementioned control method. The system boasts high efficiency and good stability. Employing a bilateral LCC topology as the core of energy transmission, its inherent constant current characteristics are suitable for battery loads and it is insensitive to parameter changes. Combined with an anti-offset coil design, drastic fluctuations in the coupling coefficient are suppressed at the hardware level. Dynamic impedance matching is achieved through software algorithms, enabling the system to operate at high efficiency across a wide coupling coefficient range, resulting in high overall transmission efficiency and strong stability.

[0064] like Figure 1 As shown, it includes:

[0065] Inverter modules are used to convert DC power to AC power;

[0066] The primary-side resonant compensation network is connected to the inverter module and is used for resonant compensation and output characteristic adjustment.

[0067] The primary-side transmitting coil and the secondary-side receiving coil form a magnetic coupling mechanism, which is connected to the primary-side resonant compensation network to resist offset.

[0068] A secondary-side resonant compensation network, connected to the magnetic coupling mechanism, is used for resonant compensation and output characteristic adjustment.

[0069] A rectifier module, coupled to the secondary receiving coil, is used to convert the induced high-frequency alternating current into direct current.

[0070] The voltage regulation and filtering module is connected to the output terminal of the rectifier module. It is used to filter and smooth the rectified DC power to output a stable DC voltage, which is then applied to the load.

[0071] The adaptive impedance matching module calculates the optimal duty cycle in real time based on the sampled system output power.

[0072] The controller module, employing a dual-transistor Buck-Boost circuit topology, is connected between the output of the rectifier module and the voltage regulator / filter module, and is also connected to the adaptive impedance matching module. It is used to control the duty cycle of the switching transistors in the adaptive impedance matching network based on the optimal duty cycle calculated by the adaptive impedance matching module. This serves as the actuator of the adaptive impedance matching module, enabling adaptive impedance matching and maximum power transfer efficiency tracking under varying coupling coefficient conditions.

[0073] In this embodiment, the bilateral LCC resonant compensation network consists of a primary-side LCC compensation circuit and a secondary-side LCC compensation circuit. The primary-side LCC compensation circuit corresponds to the primary-side transmitting coil, and the secondary-side LCC compensation circuit corresponds to the secondary-side receiving coil. The parameters of the primary-side LCC compensation circuit and the secondary-side LCC compensation circuit satisfy the resonance condition.

[0074]

[0075] Where L f1 For primary-side compensating inductance; C f1 For compensation capacitor; L f2 For secondary-side compensation inductance; C f2 C1 is the compensation capacitor; C2 is the primary inductor; C1 is the primary series capacitor; C2 is the secondary series capacitor; w is the system operating angular frequency; and L2 is the secondary inductor.

[0076] In this embodiment, the primary transmitting coil and the secondary receiving coil are DD-type coils, a three-coil structure, or an improved structure thereof, and their mutual inductance M is horizontally offset. Within the range, satisfy:

[0077]

[0078] Where M0 is the mutual inductance value during alignment. Let f be the offset effect function. min This represents the minimum coupling retention rate.

[0079] In one implementation example, the controller module calculates the real-time power by sampling the output voltage and output current of the rectifier module, obtains the corresponding system output power, and dynamically adjusts the duty cycle of the pulse width modulation signal output to the impedance matching network according to the logic of the optimized variable step size perturbation observation method.

[0080] Combination Figure 2 This invention provides a wireless charging control method for electric vehicles based on a bilateral LCC topology and adaptive impedance matching, characterized by the following three core steps:

[0081] Step S1: Establish the equivalent impedance model of the wireless power transmission system based on the bilateral LCC resonant compensation network, and determine the equivalent output impedance characteristic function of the system;

[0082] The system equivalent output impedance characteristic function is used to indicate the relationship between the system impedance D0 and the duty cycle D;

[0083] Step S2: Based on the topology parameters of the bilateral LCC resonant compensation network, the structural parameters of the coupling coil, and the rated operating parameters of the system, determine the initial duty cycle of the dual-tube Buck-Boost impedance matching circuit connected to the rectifier output terminal. According to the impedance characteristic function, the impedance matching is achieved by adjusting the duty cycle.

[0084] Step S3: The duty cycle of the dual-tube Buck-Boost circuit is dynamically optimized by using an optimized variable step size perturbation observation method. The equivalent impedance of the system is changed by continuously adjusting the duty cycle. The optimal impedance is calculated based on the impedance characteristic function, thereby achieving maximum power transfer efficiency tracking of the system under varying coupling coefficient conditions.

[0085] The theoretical basis of step S1 is to establish, as Figure 3 The exact mathematical model of the bilateral LCC resonant compensation network is shown. Figure 3 The system's main circuit topology is shown, including: DC power supply Vdc, a full-bridge inverter composed of switching transistors S1~S4, and a primary-side LCC compensation network (L f1 C f1 C f1), primary-side transmitting coil L P Secondary receiving coil L s Secondary-side LCC compensation network (L f2 C f2 C2) A full-bridge rectifier composed of diodes D1~D4, and an inductor L f Capacitor C f The rectifier comprises a dual-transistor Buck-Boost impedance matching network consisting of switching transistors Q1 and Q2, with the positive and negative terminals of the rectifier's DC output connected to the input terminals of the dual-transistor Buck-Boost impedance matching network, respectively; and a DC load R. L The coils are coupled through mutual inductance M.

[0086] To perform impedance matching analysis, it is necessary to derive the equivalent output impedance Z as seen from the inverter output terminals (points A and B). inv Based on Kirchhoff's laws and circuit theory, for Figure 3 The circuit shown is analyzed. Specifically, the input resistance R of the dual-transistor Buck-Boost circuit in continuous conduction mode (CCM) is... inBB With duty cycle D and load resistance R L Satisfying Relationship:

[0087]

[0088] The equivalent impedance of this resistor, after being referred to the AC side by a full-bridge rectifier, is Z. eq (D), its expression is:

[0089]

[0090] By establishing the equivalent impedance model of the bilateral LCC resonant compensation network, the equivalent output impedance function Z of the system viewed from the magnetic coupling side towards the load is determined. S, Its expression is:

[0091]

[0092] The primary circuit, mapped by the circuit formula, is Z. R The mutual inductance M between the coupled coils is expressed as:

[0093]

[0094] Finally, the equivalent output impedance function Z from the inverter output side to the load is obtained. S (jw,D), its expression is:

[0095]

[0096] Where L f1For primary-side compensating inductance; C f1 For compensation capacitor; L f2 For secondary-side compensation inductance; C f2 L1 is the compensation capacitor; C1 is the primary inductance; W is the primary series capacitor; L2 is the system operating angular frequency; L1 and L2 are the primary and secondary coil inductances, respectively; C1 and C2 are the primary series compensation capacitor and the secondary series capacitor, respectively. eq (D) is the equivalent load impedance including the subsequent impedance matching network; D is the duty cycle of the switching transistor in the impedance matching network; w is the system operating angular frequency.

[0097] This model reveals the system impedance function Z. S (jw,D) is a function of the duty cycle D and the coupling coefficient k (through M), and is the theoretical basis for subsequent adaptive control.

[0098] Specific implementation of step S2:

[0099] Before system startup, a reasonable initial duty cycle D0 needs to be set for the adaptive impedance matching module to ensure a smooth startup and rapid entry into the optimization process. In practice, the system's rated parameters, including the operating frequency f, should first be determined according to the application standard (such as SAE J2954) or design objectives. s Rated output power, rated coupling coefficient k0 (usually taken as the value when aligned), rated load R L as well as Figure 3 The parameters of all LCC components (must satisfy the resonance condition).

[0100] Then, substitute the rated parameters into the impedance model Z obtained in step S1. S (jw,D) can be solved numerically to solve equation R. e [Z S [(jw,D)]=R s (where R) s The initial duty cycle D0 is obtained by taking the equivalent internal resistance of the system's preceding stage (which can be calculated or estimated from circuit parameters). Alternatively, D0 can be determined through simulation scanning with the goal of maximizing the system's transmission efficiency under rated conditions. This initial value serves as the starting point for the optimized variable step size perturbation and observation method (ASS-P&O). Specific implementation of step S3:

[0101] After the system starts up and is running, the controller begins to periodically execute, such as Figure 4 The optimized variable step size perturbation observation method (ASS-P&O) is shown. Figure 4 The complete logical flow of the algorithm is clearly demonstrated.

[0102] Combination Figure 4 The algorithm executes according to the following process within each control cycle (e.g., 1ms):

[0103] S3-1 Data Acquisition (corresponding to) Figure 4 The first step after "start" is that the controller reads the voltage V at the rectifier output terminal of the current cycle (time k) from the analog-to-digital converter (ADC). o (k) and current V o (k), calculate the instantaneous output power P o (k)= V o (k)·V o (k). Meanwhile, the controller internally stores the power values ​​P from the previous two cycles. o (k-1) and P o (k-2), and the duty cycle D(k-1) of the previous cycle.

[0104] S3-2 Calculation of Change (corresponding to) Figure 4 (Previous steps in the middle rhombus judgment box) Calculate the current power change ΔP o (k)=P o (k)- P o (k-1) and the power change ΔP from the previous period o (k-1)= P o (k-1)- P o (k-2).

[0105] S3-3 Steady-state judgment (corresponding to) Figure 4 (The first diamond-shaped decision box in the middle), calculate △P o The absolute value of (k) and with the preset steady-state threshold Comparison. If < This indicates that the change in system output power is very small, and the system is determined to be in steady state or very close to the maximum power point. Therefore, the current control cycle ends, and the current duty cycle remains unchanged, i.e., D(k) = D(k-1). This effectively avoids meaningless disturbances and oscillations near the maximum power point.

[0106] S3-4 Dynamic Adjustment Decision (corresponding to) Figure 4 The two diamond-shaped decision boxes and processing boxes at the bottom center indicate that if the system has not reached a steady state, it enters the dynamic adjustment phase. The core of the algorithm lies in judging the trend of the operating point movement based on the sign of the power change: Case A (increasing the duty cycle): such as Figure 4 As shown in the left branch, if condition △P is satisfied... o (k)·△P o (k-1)≥0 indicates that the power is continuously increasing or decreasing, and the operating point is moving away from or approaching the maximum power point in one direction; or it satisfies ΔP o (k)·△P o (k-1)<0 and △Po If (k-1) < 0, it indicates a reversal in the direction of power change, but the power was previously in a downward trend and may be located to the left of the maximum power point. In both cases, the search should continue in the current direction (increasing D). At this point, the adaptive step size... ,in This is an adjustable scaling factor. Update duty cycle: D(k) = D(k-1) + ε(k). Case B (reducing duty cycle): [Example...] Figure 4 As shown in the right-hand branch, if all three conditions are met simultaneously: △P o (k)·△P o (k-1)<0 (power change direction reversed), ΔP o (k-1)>0 (power is increasing before reversal), and If the value is greater than ε (the reversal amplitude is large enough, where ε is the noise threshold), it strongly indicates that the operating point has just crossed the maximum power point. In this case, the duty cycle should be adjusted in the opposite direction and updated: D(k) = D(k-1) - ε(k). Case C (Keep): If the conditions of Case A and Case B are not met, then the duty cycle remains unchanged.

[0107] S3-5 Output and Iteration: Based on the above decision, a new duty cycle D(k) is obtained. The controller updates the duty cycle register of its PWM generator and generates the corresponding drive signal to act on the circuit. Figure 3 The switching transistors Q1 and Q2 in the circuit change the input impedance Z of the two-transistor Buck-Boost circuit. eq (D) This adjusts the impedance matching state of the entire system. The algorithm waits for the next control cycle and repeats the above process to achieve continuous, adaptive maximum power point tracking.

[0108] With fast dynamic response and high steady-state accuracy, the proposed optimized variable-step perturbation observation method innovatively correlates the adjustment step size with the gradient (power change) between the system's operating point and the maximum power point. A larger step size is used for rapid approximation when far from the maximum power point, while the step size is automatically reduced as the system approaches to suppress oscillations. This perfectly balances the trade-off between tracking speed and steady-state accuracy, significantly improving dynamic performance.

[0109] Brief description of the system hardware implementation:

[0110] When implementing the system of the present invention, Figure 3Each module shown requires the selection of appropriate components. SiC MOSFETs can be used for the inverter and Buck-Boost switching transistors to improve efficiency. The LCC compensation capacitor should be an NP0 / C0G ceramic capacitor with good high-frequency characteristics. The compensation inductor and coupling coil should be wound with Litz wire to reduce high-frequency losses; the coupling coil should preferably use a DD-type structure to improve anti-offset capability. The controller core can be a microcontroller (STM32F4 series) or a digital signal processor (DSP) with a high-speed ADC and abundant PWM resources. Control software implementation. Figure 3 The ASS-P&O algorithm logic is shown below.

[0111] The key innovation of this invention lies in the organic combination of an accurate impedance model applicable to bilateral LCC topology, a variable step-size adaptive algorithm that matches the model characteristics (the step size is dynamically adjusted according to the degree of deviation of the system from the optimal point), and an efficient dual-tube Buck-Boost actuator, forming a closed-loop control system that can quickly respond to changes in coupling coefficients and maintain efficient system operation.

[0112] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A wireless charging system for electric vehicles based on a bilateral LCC topology and adaptive impedance matching, characterized in that, The system includes: Inverter modules are used to convert DC power to AC power; The primary-side resonant compensation network is connected to the inverter module and is used for resonant compensation and output characteristic adjustment. The primary-side transmitting coil and the secondary-side receiving coil form a magnetic coupling mechanism, which is connected to the primary-side resonant compensation network to resist offset. A secondary-side resonant compensation network, connected to the magnetic coupling mechanism, is used for resonant compensation and output characteristic adjustment; A rectifier module, coupled to the secondary receiving coil, is used to convert the induced high-frequency alternating current into direct current. The voltage regulation and filtering module is connected to the output terminal of the rectifier module. It is used to filter and smooth the rectified DC power to output a stable DC voltage, which is then applied to the load. The adaptive impedance matching module calculates the optimal duty cycle in real time based on the sampled system output power. The controller module, employing a dual-transistor Buck-Boost circuit topology, is connected between the output of the rectifier module and the voltage regulator / filter module, and is also connected to the adaptive impedance matching module. It is used to control the duty cycle of the switching transistors in the adaptive impedance matching network based on the optimal duty cycle calculated by the adaptive impedance matching module. This serves as the actuator of the adaptive impedance matching module, enabling adaptive impedance matching and maximum power transfer efficiency tracking under varying coupling coefficient conditions.

2. The wireless charging system for electric vehicles based on bilateral LCC topology and adaptive impedance matching according to claim 1, characterized in that: The bilateral LCC resonant compensation network consists of a primary-side LCC compensation circuit and a secondary-side LCC compensation circuit. The primary-side LCC compensation circuit corresponds to the primary-side transmitting coil, and the secondary-side LCC compensation circuit corresponds to the secondary-side receiving coil. The parameters of the primary-side and secondary-side LCC compensation circuits satisfy the resonance condition, the expression of which is: Where L f1 For primary-side compensating inductance; C f1 For compensation capacitor; L f2 For secondary-side compensation inductance; C f2 C1 is the compensation capacitor; C2 is the primary inductor; C1 is the primary series capacitor; C2 is the secondary series capacitor; w is the system operating angular frequency; and L2 is the secondary inductor.

3. The wireless charging system for electric vehicles based on bilateral LCC topology and adaptive impedance matching according to claim 1, characterized in that: The primary transmitting coil and the secondary receiving coil are DD-type coils, a three-coil structure, or an improved structure thereof, and their mutual inductance M is horizontally offset. Within the range, satisfy: Where M0 is the mutual inductance value during alignment. Let f be the offset effect function. min This represents the minimum coupling retention rate.

4. The wireless charging system for electric vehicles based on bilateral LCC topology and adaptive impedance matching according to claim 1, characterized in that: The controller module calculates the real-time power by sampling the output voltage and output current of the rectifier module, obtains the corresponding system output power, and dynamically adjusts the duty cycle of the pulse width modulation signal output to the adaptive impedance matching network according to the logic of the optimized variable step size perturbation observation method.

5. A wireless charging control method for electric vehicles based on bilateral LCC topology and adaptive impedance matching, used to control the wireless charging system for electric vehicles as described in claims 1 to 4, characterized in that, Includes the following steps: Step S1: Establish the equivalent impedance model of the wireless power transmission system based on the bilateral LCC resonant compensation network, and determine the equivalent output impedance characteristic function of the system; Step S2: Based on the topology parameters of the bilateral LCC resonant compensation network, the structural parameters of the coupling coil, and the rated operating parameters of the system, determine the initial duty cycle of the dual-tube Buck-Boost adaptive impedance matching circuit connected to the rectifier output terminal. According to the impedance characteristic function, the impedance matching is achieved by adjusting the duty cycle. Step S3: The duty cycle of the dual-transistor Buck-Boost circuit is dynamically optimized using the optimized variable step size perturbation observation method. The equivalent impedance of the system is changed by continuously adjusting the duty cycle, and the optimal impedance is calculated based on the impedance characteristic function.

6. The wireless charging control method for electric vehicles based on bilateral LCC topology and adaptive impedance matching according to claim 5, characterized in that: In step S1, by establishing the equivalent impedance model of the bilateral LCC resonant compensation network, the equivalent output impedance function Z of the system viewed from the magnetic coupling side towards the load is determined. s Its expression is: When the system operates under resonance conditions, its expression is: The expression for the mutual inductance M between the coupled coils is: The equivalent load impedance Z after adaptive impedance matching network in dual-tube Buck-Boost converter eq (D), its expression is: Where L2 is the secondary inductor; C2 is the series capacitor on the multiple sides; L f2 For secondary-side compensation inductance; C f2 The capacitor is the compensation capacitor; D is the duty cycle of the switch in the adaptive impedance matching network; R L ω is the load resistance; w is the system operating angular frequency; it characterizes the impedance characteristics under the combined action of the primary-side LCC circuit, the secondary-side LCC circuit, the magnetic coupling mechanism, and the load.

7. The wireless charging control method for electric vehicles based on bilateral LCC topology and adaptive impedance matching according to claim 6, characterized in that: In step S2, based on the above equivalent output impedance function and system operating parameters, the circuit formula maps to the primary circuit as Z. R Determine the equivalent output impedance Z of the system after adaptive adjustment. S (jw,D) and Z R The functional relationship is as follows: Z R For the reflective resistor, its expression is: System output power P o The relationship with the adjusted impedance is as follows: The equivalent load impedance Z after adaptive impedance matching network in dual-tube Buck-Boost converter eq (D), its expression is: Among them, V inv L is the fundamental effective value of the inverter output voltage; f1 For primary-side compensating inductance; C f1 C1 is the primary series capacitor; M is the mutual inductance of the coils; w is the system operating angular frequency; R e [] indicates taking the real part of the complex number; ‖ indicates taking the modulus of the complex number, and the initial parameters of the module are set accordingly; the adaptive impedance matching module changes the equivalent load impedance by adjusting the duty cycle of the power switching devices in the impedance matching network.

8. The wireless charging control method for electric vehicles based on bilateral LCC topology and adaptive impedance matching according to claim 5, characterized in that: In step S3, the specific steps of the optimized variable step size perturbation observation method include: Step S3-1: Obtain the adaptive impedance matching module parameters of the system at time k-1. And the system output power P at times k, k-1, and k-2 o (k), P o (k-1), P o (k-2); Step S3-2: Calculate the change in system output power ΔP between adjacent time points. o (k)=P o (k)-P o (k-1) and △P o (k-1)=P o (k-1)- P o (k-2), and calculate △P o The absolute value of (k); Step S3-3: Determine if the system has entered a steady state: If the absolute value is less than the preset steady-state threshold... If the condition is met, the state is considered stable, and the current adjustment cycle ends; otherwise, proceed to step S3-4. Step S3-4: Determine the trend of the system's operating point change: △P o (k) and △P o The product of (k-1) is positive, or the product is negative but ΔP o If (k-1) < 0, then the operating point is determined to have moved toward the maximum power point or is in a specific deviation state, and the parameters will be increased. Add an adaptive step size ε to obtain the updated parameters. Otherwise, keep the parameters unchanged; wherein, the size of the adaptive step size ε is related to... Positive correlation.

9. A wireless charging control method for electric vehicles based on bilateral LCC topology and adaptive impedance matching according to claim 5 or 8, characterized in that: In step S3, by optimizing the parameters of the adaptive impedance matching module, the real part of the adjusted system's equivalent output impedance Re[Z] is made so that... s [jw,D] and the load equivalent resistance R L This ensures a match, thereby maximizing the tracking of the system's output power.

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