Parameter optimization method and system of wireless power transmission system

Abstract

The application discloses a parameter optimization method and system of a wireless power transmission system. The method comprises the following steps: before the system is operated, optimizing the capacitance parameter of a resonance compensation network with the minimum overall capacitance deviation tolerance of the resonance compensation network as an optimization target; and / or during the operation of the system, controlling the frequency of an inverter by using a frequency tracking method based on the sensitivity analysis result obtained before the system is operated or by taking the minimum overall capacitance deviation tolerance of the resonance compensation network as an optimization target. The application adjusts the capacitance parameter and / or the frequency parameter of the inverter from the perspective of parameter optimization and / or frequency control, so as to improve the capacitance parameter deviation tolerance of the system.

Description

Technical Field

[0001] This invention relates to the field of wireless power transmission system technology, and specifically to a parameter optimization method and system for wireless power transmission systems. Background Technology

[0002] Wireless power transmission systems typically have low coupling coefficients and high leakage inductance in their coupling coils. Resonant compensation networks can reduce reactive power in wireless power transmission systems, thereby improving transmission efficiency; therefore, they are an essential component. Resonant compensation networks are usually composed of capacitors and / or inductors connected in series and / or parallel. Achieving resonance requires high accuracy and stability of the parameters. If the parameters of the resonant components deviate from their rated values ​​due to aging, temperature changes, or other factors during operation, the resonance state is disrupted, leading to increased reactive power and reduced efficiency in the system. In practical systems, compensation capacitors have several accuracy grades, such as 10% and 5%. Aging and temperature rise can also cause changes in capacitance values. Therefore, compared to precise compensation, detuning is a common occurrence in wireless power transmission systems. It is necessary to analyze the impact of parameter deviations on the characteristics of wireless power transmission systems and take corresponding measures to improve the tolerance of capacitor parameter deviations.

[0003] Some researchers intentionally operate systems in a detuned state to obtain certain superior characteristics. For example, through detuning design, SS-compensated systems can maintain relatively stable output power even when the coupling coefficient changes. Although detuning design reduces the stringent requirements for resonance to some extent, the above research still requires the system to operate at a specific resonant point, and changes in capacitance parameters will still cause changes in the system's operating state. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is how to improve the tolerance of capacitor parameter deviation in a wireless power transmission system, thereby providing a parameter optimization method and system for a wireless power transmission system.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] In a first aspect, embodiments of the present invention provide a parameter optimization method for a wireless power transmission system. The wireless power transmission system includes an inverter, a resonant compensation network, and a rectifier connected in sequence. The method includes: optimizing the capacitance parameters of the resonant compensation network before system operation, with the goal of minimizing the overall capacitance deviation tolerance of the resonant compensation network; and / or, during system operation, controlling the frequency of the inverter by applying a frequency tracking method based on the sensitivity analysis results obtained before system operation or with the goal of minimizing the overall capacitance deviation tolerance of the resonant compensation network.

[0007] In one embodiment, the process of optimizing the capacitor parameters of the resonant compensation network with the goal of minimizing the overall capacitance deviation tolerance of the resonant compensation network includes: establishing a set of preset capacitance deviation values ​​for each capacitor in the resonant compensation network; selecting any one preset capacitance deviation value from each set to form multiple sets of preset capacitance deviation values ​​for the resonant compensation network; for each set of preset capacitance deviation values ​​for the resonant compensation network, calculating the extreme values ​​of output voltage, power factor, voltage of each capacitor, and transmission efficiency variation within the preset adjustment range of each capacitor's preset capacitance deviation value; calculating the evaluation index value of the overall capacitance deviation tolerance of the resonant compensation network based on the extreme values ​​and their corresponding preset weight values; and calculating the design value of the capacitor of the resonant compensation network based on the preset capacitance deviation values ​​of the resonant compensation network corresponding to the extreme value with the minimum evaluation index value.

[0008] In one embodiment, the process of controlling the inverter frequency using a frequency tracking method based on sensitivity analysis results obtained before system operation includes: before system operation, analyzing the influence of the capacitance deviation value of each capacitor in the resonant compensation network on the system output to obtain a sensitivity index value for the capacitance deviation value of each capacitor; taking the deviation value of the capacitor with the largest sensitivity index value as the most sensitive factor, thus the capacitor with the largest sensitivity index value is the most sensitive capacitor; during system operation, using a frequency tracking strategy, maintaining the frequency at the frequency that makes the capacitance deviation of the most sensitive capacitor zero.

[0009] In one embodiment, the process of controlling the inverter frequency using a frequency tracking method based on sensitivity analysis further includes: using a variance-based Sobol sensitivity analysis method to analyze the influence of the capacitance deviation value of each capacitor in the resonant compensation network on the system output, and obtaining the first-order effect index value of the capacitance deviation value of each capacitor; the first-order effect index value is the sensitivity index value.

[0010] In one embodiment, the process of controlling the inverter frequency with the goal of minimizing the overall capacitance deviation tolerance of the resonant compensation network includes: obtaining the real-time capacitance value of each capacitor in the resonant compensation network; obtaining the relationship expression between the real-time evaluation index of the overall capacitance deviation tolerance of the resonant compensation network and the operating frequency based on the real-time capacitance value of each capacitor and the electrical information parameters of the wireless power transmission system; using an optimization algorithm to calculate the operating frequency that makes the changes in output voltage, power factor, voltage of each capacitor, and transmission efficiency within a preset range, and that optimizes the real-time evaluation index of the overall capacitance deviation tolerance; and adjusting the inverter frequency to the calculated optimal operating frequency.

[0011] In one embodiment, when the parameter optimization method only involves controlling the frequency of the inverter, the design value of the capacitor is an ideal value.

[0012] Secondly, embodiments of the present invention provide a parameter optimization system for a wireless power transmission system. The wireless power transmission system includes an inverter, a resonant compensation network, and a rectifier connected in sequence. The system includes: a parameter optimization module, used to optimize the capacitance parameters of the resonant compensation network before system operation, with the goal of minimizing the overall capacitance deviation tolerance of the resonant compensation network; and / or a frequency control module, used to control the frequency of the inverter during system operation by applying a frequency tracking method based on the sensitivity analysis results obtained before system operation or with the goal of minimizing the overall capacitance deviation tolerance of the resonant compensation network.

[0013] Thirdly, embodiments of the present invention provide a computer device, including: at least one processor, and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to cause the at least one processor to perform the parameter optimization method of the wireless power transmission system of the first aspect of the present invention.

[0014] Fourthly, embodiments of the present invention provide a computer-readable storage medium storing computer instructions for causing a computer to execute a parameter optimization method for a wireless power transmission system according to the first aspect of the present invention.

[0015] The technical solution of this invention has the following advantages:

[0016] The present invention provides a parameter optimization method and system for a wireless power transmission system. Before system operation, the capacitor parameters of the resonant compensation network are optimized with the goal of minimizing the overall capacitance deviation tolerance of the resonant compensation network. And / or, during system operation, the inverter frequency is controlled using a frequency tracking method based on sensitivity analysis results obtained before system operation, or with the goal of minimizing the overall capacitance deviation tolerance of the resonant compensation network. This invention, from the perspective of parameter optimization and / or frequency control, adjusts capacitor parameters and / or inverter frequency parameters to improve the system's capacitance parameter deviation tolerance. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 A topology diagram of a wireless power transmission system provided in an embodiment of the present invention;

[0019] Figures 2(a) to 2(c) A flowchart illustrating a specific example of the parameter optimization method provided in this embodiment of the invention;

[0020] Figure 3 An equivalent topology diagram of a wireless power transmission system provided in an embodiment of the present invention;

[0021] Figure 4 A flowchart illustrating a specific example of the parameter optimization method provided in this embodiment of the invention;

[0022] Figure 5 A flowchart illustrating a specific example of the parameter optimization method provided in this embodiment of the invention;

[0023] Figure 6 The sensitivity ranking results provided in the embodiments of the present invention;

[0024] Figure 7 A flowchart illustrating a specific example of the parameter optimization method provided in this embodiment of the invention;

[0025] Figure 8 Experimental waveform diagrams provided for embodiments of the present invention;

[0026] Figures 9(a) to 9(c) A composition diagram of a specific example of the parameter optimization system provided in an embodiment of the present invention;

[0027] Figure 10 This is a composition diagram of a specific example of a computer device provided in an embodiment of the present invention. Detailed Implementation

[0028] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0030] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0031] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] Example 1

[0033] This invention provides a parameter optimization method for a wireless power transmission system, such as... Figure 1 As shown, the wireless power transmission system includes an inverter, a resonant compensation network, and a rectifier connected in sequence, wherein the resonant compensation network is an LCC-S compensation network.

[0034] As shown in Figures 2(a) and 2(c), the parameter optimization methods for wireless power transfer systems include:

[0035] Step S11: Before the system runs, optimize the capacitance parameters of the resonant compensation network with the goal of minimizing the overall capacitance deviation tolerance of the resonant compensation network.

[0036] And / or,

[0037] Step S12: During system operation, the frequency of the inverter is controlled by applying a frequency tracking method based on the sensitivity analysis results obtained before system operation or by minimizing the overall capacitance deviation tolerance of the resonant compensation network.

[0038] Step S12 includes two cases:

[0039] (1) Step S121: During system operation, the frequency of the inverter is controlled by applying the frequency tracking method based on the sensitivity analysis results obtained before system operation. (2) Or step S122: During system operation, the frequency of the inverter is controlled by minimizing the overall capacitance deviation tolerance of the resonant compensation network as the optimization objective.

[0040] As shown in Figures 2(a) and 2(c), embodiments of the present invention can optimize the capacitor parameters of the resonant compensation network only before system operation; or control the inverter frequency only during system operation based on the sensitivity analysis results obtained before system operation; or optimize the capacitor parameters of the resonant compensation network before system operation and control the inverter frequency during system operation. The specific methods are as follows:

[0041] (1) Step S11: Before the system runs, optimize the capacitance parameters of the resonant compensation network with the goal of minimizing the overall capacitance deviation tolerance of the resonant compensation network.

[0042] (2) Step S121: During system operation, the frequency of the inverter is controlled by applying the frequency tracking method based on the sensitivity analysis results obtained before system operation.

[0043] (3) Step S122: During system operation, the frequency of the inverter is controlled with the goal of minimizing the overall capacitance deviation tolerance of the resonant compensation network.

[0044] (4) Step S11: Before the system is running, optimize the capacitance parameters of the resonant compensation network with the goal of minimizing the overall capacitance deviation tolerance of the resonant compensation network; Step S121: During the system operation, use the frequency tracking method based on the sensitivity analysis results obtained before the system is running to control the frequency of the inverter.

[0045] (5) Step S11: Before the system is running, optimize the capacitance parameters of the resonant compensation network with the goal of minimizing the overall capacitance deviation tolerance of the resonant compensation network; Step S122: During the system operation, control the frequency of the inverter with the goal of minimizing the overall capacitance deviation tolerance of the resonant compensation network.

[0046] In one specific embodiment, the schematic diagram of the LCC-S compensation topology is as follows: Figure 3 As shown, U P and U S These are the fundamental RMS values ​​of the inverter output and the secondary rectifier input voltages, respectively. r and C r These are the primary-side series compensation inductor and the parallel compensation capacitor, CP and C S These are the primary and secondary series compensation capacitors, L P and L S It is the self-inductance of the primary and secondary coils, R E This is the equivalent load resistance, and M is the mutual inductance. Figure 3 Taking the topology shown as an example, when the inductor and capacitor parameters in the LCC-S compensation network satisfy equation (1), the rectifier output voltage calculation formula is shown in equation (2).

[0047]

[0048]

[0049] In the formula, ω0 is the ideal value of the resonant frequency. In the embodiments of the present invention, all subscripts 0 represent the ideal value without considering the deviation of the capacitor parameters.

[0050] Under conditions of capacitor parameter deviation, the rectifier output voltage deviation is:

[0051]

[0052] In the formula,

[0053]

[0054]

[0055] C r =k r C r0 C p =k p C p0 C s =k s C s0 (6)

[0056] In the formula, k r k p k s C r C p C s The capacitance deviation value; C r0 C p0 C s0 C r C p C s The ideal value of capacitance.

[0057] The load impedance Z of the inverter in The calculation formula is as follows:

[0058]

[0059] The formula for calculating the power factor λ is as follows:

[0060]

[0061] Where Re[] represents the real part of the expression within the box.

[0062] As can be seen from the above, C r C p C s Capacitance deviation value k r k p k s This will affect the output voltage, power factor, voltage of each capacitor, and the change in transmission efficiency. Therefore, before the system operates, this application can optimize the capacitor parameters of the resonant compensation network with the goal of minimizing the overall capacitance deviation tolerance of the resonant compensation network (i.e., step S11). Figure 4 As shown, step S11 is executed from steps S21 to S24, specifically as follows:

[0063] Step S21: Establish a set of preset values ​​for capacitance deviation of each capacitor in the resonant compensation network. Select any one preset value for capacitance deviation from each set to form multiple sets of preset values ​​for capacitance deviation of the resonant compensation network.

[0064] Specifically, a preset capacitance deviation value for each capacitor is set before the system runs, for example: C r C p C s The preset value of capacitance deviation k r k p k s The value range of C is (0.9~1.1). r C p C s The preset values ​​for capacitance deviation are all taken within the range of 0.9 to 1.1, resulting in multiple sets of preset values ​​for capacitance deviation, for example: k r k s k p The values ​​are 0.9, 0.9, and 1.1 respectively.

[0065] Step S22: For the preset value of the capacitor deviation of each group of resonant compensation networks, calculate the extreme values ​​of the output voltage, power factor, voltage of each capacitor, and change in transmission efficiency, respectively, based on the preset adjustment range of the preset value of the capacitor deviation of each capacitor.

[0066] For example, for k r k s k pGiven a set of data points of 0.9, 0.9, and 1.1, the preset adjustment range for the capacitance deviation of each capacitor is ±10%. Based on k... r =0.8~1,k s =0.8~1,k p =1~1.2, solve the extreme values ​​of output voltage, power factor, voltage of each capacitor, and change in transmission efficiency by formula (1)~(8).

[0067] Step S23: Calculate the evaluation index value of the overall capacitance deviation tolerance of the resonant compensation network based on the extreme values ​​and their corresponding preset weight values.

[0068] Specifically, due to k r k s k p The impact on output voltage, power factor, and other transmission characteristics varies, and trade-offs between these characteristics are unavoidable. Therefore, this invention defines a comprehensive index ψ reflecting the capacitance deviation tolerance of the WPT system, calculated as follows:

[0069]

[0070] In the formula, and Let λ represent the maximum and minimum values ​​of the output voltage, respectively. min This represents the minimum power factor. C respectively r C p C s The maximum value of the capacitor voltage, Δη max This represents the maximum decrease in transmission efficiency.

[0071] Step S24: Calculate the design value of the capacitance of the resonant compensation network based on the preset value of the capacitance deviation of a set of resonant compensation networks corresponding to the extreme value with the minimum evaluation index value.

[0072] Specifically, the preset value of the capacitance deviation of a set of resonant compensation networks corresponding to the extreme value with the minimum evaluation index value is substituted into equation (6) to calculate the design value of the capacitance of the resonant compensation network.

[0073] In one specific embodiment, such as Figure 5 As shown, the process of controlling the inverter frequency using a frequency tracking method based on sensitivity analysis results obtained before system operation includes:

[0074] Step S31: Before the system runs, analyze the influence of the capacitance deviation value of each capacitor in the resonant compensation network on the system output, and obtain the sensitivity index value of the capacitance deviation value of each capacitor.

[0075] Specifically, in the preceding analysis, C in the LCC-S compensation network r C p C s The degree of impact on capacitance tolerance was not differentiated, and since capacitors at different locations resonate with different inductors, theoretically C... r With L r Resonance, and C S With L S Resonance. The degree of impact of capacitor deviation at different locations on system characteristics may vary. Since capacitor parameter deviations are unpredictable and unavoidable, theoretically, the system tolerance can be improved by reducing or eliminating the deviation of the capacitor that has the most significant impact on system characteristics. Therefore, it is necessary to first analyze the degree of impact of the capacitor deviation value of each capacitor in the resonance compensation network on the system output and rank the degree of impact.

[0076] Furthermore, in this embodiment of the invention, the Sobol sensitivity analysis method based on variance is used to analyze the influence of the capacitance deviation value of each capacitor in the resonant compensation network on the system output, and to obtain the first-order effect index value of the capacitance deviation value of each capacitor; the first-order effect index value is the sensitivity index value.

[0077] Specifically, sensitivity analysis is an effective method for analyzing the influence of multiple factors on the system output. The variance-based Sobol sensitivity analysis method is a general sensitivity analysis method that is not limited to equation expressions. This method is simple and easy to operate; it only requires first constructing a Sobol sequence, then calculating the variance of each independent variable with respect to the output to determine the importance of each independent variable. This embodiment of the invention uses a first-order effect index as the importance criterion. The calculation process is as follows: for a model Y = f(X1, X2, ... X... k ), the i-th independent variable X i First-order effect index S i It can be calculated using the following formula. Specifically, in the actual formula (10), Y = f(k r ,k s ,k p ).

[0078]

[0079] In the formula, E(Y|X) i Y is taken from X. i The average of all possible values ​​other than Y|X, V[E(Y|X)] i )] is the parameter E(Y|X i Taken from all possible X iThe variance of the value, V(Y) is the total variance. Using Sobol sensitivity analysis, the first-order effect indices of the three compensation capacitors on output voltage and other parameters can be obtained, such as... Figure 6 As shown.

[0080] Step S32: The deviation value of the capacitor with the largest sensitivity index value is taken as the most sensitive factor. The capacitor with the largest sensitivity index value is the most sensitive capacitor.

[0081] Step S33: During system operation, the frequency is maintained at the frequency that makes the capacitance deviation of the most sensitive capacitor zero through a frequency tracking strategy.

[0082] For example, if C is calculated based on step S33 s Since it is the most sensitive capacitor, the secondary-side series compensation capacitor C should be reduced or even eliminated. s The deviation can effectively improve the capacitance tolerance of the system. A direct way to reduce the deviation of the secondary-side compensation capacitor is to use high-precision, high-stability capacitors, such as NP0 capacitors. However, on the one hand, high precision means high cost; on the other hand, capacitance values ​​caused by aging and temperature changes cannot be avoided. Another method is to monitor the secondary-side capacitance C in real time. s The capacitance value is adjusted to change the inverter's operating frequency to the resonant frequency of the secondary side, thereby eliminating the compensation error on the secondary side. The formula for calculating the adjusted operating frequency ω of the inverter is as follows:

[0083]

[0084] k ω Let k represent the ratio between the adjusted operating frequency ω and the ideal operating frequency ω0. ω With k S The relationship between them can be represented by (11).

[0085]

[0086] Adjusting the operating frequency can eliminate the compensation error on the secondary side, but it relatively increases the deviation between the two compensation capacitors on the primary side. Therefore, it is necessary to analyze the impact of the frequency tracking strategy on system output voltage, power factor, and other indicators. The expressions for the output voltage change ratio and the inverter's load impedance after frequency modulation are shown in the following equations:

[0087]

[0088]

[0089] in,

[0090]

[0091] Specifically, C p For the most sensitive capacitor, L needs to be made p and C p The circuit formed and C r Resonance, because considering C r If it changes, then it should be considered as L. p and C p The circuit formed and L r "Resonance", then:

[0092]

[0093]

[0094] Therefore k ω With k P The relationship between them can be represented as

[0095]

[0096] Similarly, if C r For the capacitor with the highest sensitivity, then

[0097]

[0098] Specifically, during system operation, the capacitance value of the most sensitive capacitor can be obtained by detecting the voltage and current of the secondary compensation capacitor. Voltage and current sensors are used to obtain the terminal voltage and current flowing through the capacitor, respectively, and the capacitance value can be easily obtained through a true RMS chip such as AD637.

[0099] In one specific embodiment, when the parameter optimization method only involves controlling the frequency of the inverter, the design value of the capacitor is an ideal value.

[0100] In one specific embodiment, such as Figure 7 As shown, the process of controlling the inverter frequency with the goal of minimizing the overall capacitance deviation tolerance of the resonant compensation network includes:

[0101] Step S41: Obtain the real-time capacitance value of each capacitor in the resonant compensation network.

[0102] Step S42: Based on the real-time capacitance value of each capacitor and the electrical information parameters of the wireless power transmission system, obtain the relationship expression between the real-time evaluation index of the overall capacitance deviation tolerance of the resonant compensation network and the operating frequency.

[0103] Specifically, after obtaining the real-time capacitance value of each capacitor in the resonant compensation network, the input voltage, output voltage, power factor, voltage of each capacitor, and change in transmission efficiency can be calculated using equations (1) to (8).

[0104] Specifically, when the parameter optimization method only involves controlling the inverter frequency (i.e., when implementing step S12), the capacitor's design value is an ideal value. The formula for calculating the capacitor deviation tolerance real-time index χ is as follows:

[0105]

[0106] Among them, U Cr U Cp U Cs Cr and C respectively p C s The capacitor voltage is η, and η is the efficiency from the primary inverter output to the secondary rectifier input stage. The ratio of the output voltage after capacitor deviation to the ideal output voltage. For Cr, C p C s Δη is the ratio of the terminal voltage after capacitor deviation to the terminal voltage under ideal conditions, representing the decrease in transmission efficiency caused by capacitor deviation. α1, α2, and α3 are weighting coefficients. Since efficiency is the most important indicator in wireless power transmission systems, and output voltage characterizes the system's output power capability, these weighting coefficients are set to 0.5, 0.1, and 1, respectively.

[0107] Step S43: Using an optimization algorithm, calculate the operating frequency that optimizes the output voltage, power factor, voltage of each capacitor, and transmission efficiency variation within a preset range, as well as the overall capacitor deviation tolerance real-time evaluation index.

[0108] Step S44: Adjust the inverter frequency to the calculated optimal operating frequency.

[0109] Specifically, steps S41 to S43 are implemented after each adjustment of the inverter frequency, thereby improving the capacitor deviation tolerance simply by controlling the inverter frequency to the optimal operating frequency, provided that the capacitor value is the design value or ideal value of step S11.

[0110] To further verify the correctness of step S11, embodiment k of the present invention... r k P and k S Scan from 0.9 to 1.1 at intervals of 0.005. For each group (k) r ,k P ,k S), calculate the extreme values ​​of each index and ψ in (9), the optimal results are shown in Table 1 (NO.3), and compare them with the results of not implementing step S11 and step S12 (NO.1), and only implementing step S11 (NO.2). In order to avoid large changes in the system transmission characteristics, the output voltage of implementing step S11 is designed to be limited to less than 5% compared with the ideal value.

[0111] Table 1

[0112]

[0113] It should be noted that the calculation results for NO.2 and NO.3 at the design point are relative to the calculation for NO.1, while k US-max k US-min k UCr-max k UCP-max and k UCS-max This is compared to the value at each design point. For example, when the compensation parameter (k) r ,k P ,k S When k is (1.040, 1.065, 1.100), the output voltage of NO.3 drops to 0.950 times its rated value, while the extreme value of the output voltage caused by the capacitor deviation is 1.12·M / Lr. Therefore, k US-max The value is 1.12 / 0.950 = 1.263.

[0114] As can be seen from Table 1, implementing only step S11 does not significantly change the extreme values ​​of the output voltage compared to the ideal compensation condition. However, when implementing step S12, k... US-max From 1.125 to 1.263, k US-min The power factor also increased from 0.781 to 0.859; the minimum power factor reached 0.905, while the value without any improvement measures was only 0.758, and the value with only compensation parameter optimization was only 0.781. Theoretically, the inverter capacity can be reduced by 16.32% and 10.94% compared to NO.1 and NO.2, respectively. After implementing steps S11 and S12, the transmission efficiency became more stable, with a maximum decrease of only 0.353%. Although the cost is k... UCr-max k UCP-max and k UCS-max Rising, but k UCr k UCP and k UCS Since all values ​​are less than 1, the absolute values ​​of the maximum voltages of the three capacitors do not change significantly. Overall, through the proposed steps S11 and S12, the capacitance deviation tolerance is improved from 0.432 (unoptimized) and 0.391 (step S11 only) to 0.361, verifying the correctness and effectiveness of the embodiments of the present invention.

[0115] To verify the effectiveness of the proposed frequency tracking strategy and compensation parameter optimization, experiments were conducted on a 22kW WPT prototype. Since the capacitor is finite and its capacitance is discontinuous, an error exists between the expected capacitance and the actual capacitance in the experiment. For example, the ideal compensation condition (C...) r C P C S The theoretical capacitances are (172.04nF, 87.18nF, 34.65nF), while the actual capacitances are (171.96nF, 87.11nF, 34.67nF). However, the error between the actual and expected values ​​is very small and can be ignored.

[0116] Three sets of verification experiments were conducted, corresponding to the three sets in Table 1. The conditions under which the transmission characteristic indicators exhibited extreme values ​​(i.e., capacitor output voltage, power factor, transmission efficiency, and voltage stress) were tested respectively. Some waveforms are shown below. Figure 8 As shown. Figure 8 in,u O This is the secondary-side rectified output voltage. Voltage: 500V / div. Current: 100A / div for (a) and (b), 50A / div for the others. Time: 10μs / division. Unoptimized, (a) ideal compensation condition and (b) minimum power factor condition. Compensation parameter optimization only (only step S11 is implemented), (c) ideal compensation condition and (d) minimum power factor condition. Frequency tracking strategy and compensation parameter optimization are applied simultaneously (steps S11 and S12 are implemented), (e) ideal compensation condition and (f) minimum power factor condition.

[0117] from Figure 8 As can be seen from (b) and (d), when the system operates under minimum power factor conditions, the load impedance of the primary-side inverter is capacitive regardless of whether the compensation parameters are optimized, which will reduce the efficiency of the primary-side converter. However, the situation changes when the frequency tracking method is used in conjunction with compensation parameter optimization. According to theoretical calculations, the minimum power factor and minimum transmission efficiency (NO.3) in Table 1 occur simultaneously. Figure 8As shown in (f), the inductive load impedance causes the primary-side inverter to operate in a zero-voltage switching (ZVS) state, which is beneficial for efficient energy transfer. According to Tables 1 and 2, there are certain errors between the experimental results and the theoretical analysis. This is partly because the influence of parasitic parameters, such as converter losses, and the parasitic resistance of the coils and compensation capacitors, was ignored in the theoretical calculations. On the other hand, the deviation between the actual compensation capacitor and the expected value also contributes to the experimental error. The experimental errors in output voltage and power factor are less than 5%, and the voltage stress error of the compensation capacitor is less than 10%. In the theoretical calculations, the coil quality factor was set to a constant value of 200, which may be lower than the actual value, resulting in a higher measured conversion efficiency from the three-phase input to the secondary rectified output. After applying a frequency tracking strategy and optimizing the compensation parameters, the output voltage under the designed compensation conditions decreased from 495.4V to 463.8V, a decrease of 6.4%, almost the same as the decrease rate under the condition of only adjusting the compensation parameters. Considering a ±10% capacitor error, the minimum output voltage increased from 338.9V to 398.8V, an increase of 17.6%, while the increase after optimizing compensation parameters alone was only 11.6%. Furthermore, after optimizing the compensation parameters, the minimum power factor improved from 0.78 to 0.86. When the frequency tracking method is implemented simultaneously, the minimum power factor can be further improved to 0.89. This results in a maximum reduction of 15.9% in the apparent power of the inverter output, which is clearly beneficial for reducing inverter capacity and system cost. Although the capacitor voltage index did not improve significantly, the transmission efficiency increased from 93.2% to 94.8% under the design compensation conditions, which is a high efficiency with a 20cm air gap. The efficiency improvement is due to the primary inverter operating in ZVS mode after adjusting the compensation parameters. Another reason is the reduction in capacitor losses due to the lower capacitor voltage. When using the frequency tracking strategy, the transmission efficiency is slightly lower than under the compensation parameter optimization condition (NO.2), by approximately 0.2%, which is negligible. Another benefit of optimizing the compensation parameters is that the maximum decrease in transmission efficiency is significantly reduced from 5.9% to 0.6%, due to the expanded ZVS region. However, when only the compensation parameters are optimized, the transmission efficiency can decrease by up to 2.5%. Although the maximum voltage rise rate increases from 12.4% to 26.4%, the overall capacitance tolerance increases from 0.485 to 0.363, representing an improvement of 25.2%, while the improvement under the compensation parameter optimization condition is only 21.0%. Therefore, the experimental results demonstrate that the proposed frequency tracking method and compensation parameter optimization can effectively improve the capacitance tolerance of the WPT system.

[0118] Table 2

[0119]

[0120] Example 2

[0121] This invention provides a parameter optimization system for a wireless power transmission system. The wireless power transmission system includes an inverter, a resonant compensation network, and a rectifier connected in sequence, such as... Figures 9(a) to 9(c) As shown, the system includes:

[0122] The parameter optimization module 1 is used to optimize the capacitance parameters of the resonant compensation network before the system runs, with the goal of minimizing the overall capacitance deviation tolerance of the resonant compensation network. This module executes the method described in step S11 of embodiment 1, which will not be repeated here.

[0123] And / or,

[0124] Frequency control module 2 is used to control the frequency of the inverter during system operation by applying a frequency tracking method based on the sensitivity analysis results obtained before system operation or by minimizing the overall capacitance deviation tolerance of the resonant compensation network as the optimization objective. This module executes the method described in step S12 of embodiment 1, which will not be repeated here.

[0125] Example 3

[0126] This invention provides a computer device, such as... Figure 10 As shown, the system includes: at least one processor 401, such as a CPU (Central Processing Unit), at least one communication interface 403, a memory 404, and at least one communication bus 402. The communication bus 402 is used to enable communication between these components. The communication interface 403 may include a display screen or a keyboard; optionally, the communication interface 403 may also include a standard wired interface or a wireless interface. The memory 404 may be high-speed RAM (Random Access Memory) or non-volatile memory, such as at least one disk storage device. Optionally, the memory 404 may also be at least one storage device located remotely from the processor 401. The processor 401 can execute the parameter optimization method of the wireless power transmission system of Embodiment 1. The memory 404 stores a set of program code, and the processor 401 calls the program code stored in the memory 404 to execute the parameter optimization method of the wireless power transmission system of Embodiment 1.

[0127] The communication bus 402 can be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus, etc. The communication bus 402 can be divided into an address bus, a data bus, and a control bus, etc. For ease of representation, Figure 10 The symbol is represented by only one line, but this does not mean that there is only one bus or one type of bus.

[0128] The memory 404 may include volatile memory, such as random-access memory (RAM); the memory may also include non-volatile memory, such as flash memory, hard disk drive (HDD) or solid-state drive (SSD); the memory 404 may also include a combination of the above types of memory.

[0129] The processor 401 can be a central processing unit (CPU), a network processor (NP), or a combination of CPU and NP.

[0130] The processor 401 may further include a hardware chip. This hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The PLD may be a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), a generic array logic (GAL), or any combination thereof.

[0131] Optionally, the memory 404 is also used to store program instructions. The processor 401 can call the program instructions to implement the parameter optimization method of the wireless power transmission system as described in Embodiment 1 of this application.

[0132] This invention also provides a computer-readable storage medium storing computer-executable instructions that can execute the parameter optimization method for the wireless power transmission system of Embodiment 1. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk drive (HDD), or solid-state drive (SSD), etc.; the storage medium may also include combinations of the above types of memory.

[0133] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A parameter optimization method for a wireless power transmission system, characterized in that, The wireless power transmission system includes an inverter, a resonant compensation network, and a rectifier connected in sequence, and the method includes: Before the system is put into operation, the capacitance parameters of the resonant compensation network are optimized with the goal of minimizing the overall capacitance deviation tolerance of the resonant compensation network. During the operation of the system, the frequency of the inverter is controlled by applying a frequency tracking method based on the sensitivity analysis results obtained before the system is started, or by taking the minimum overall capacitance deviation tolerance of the resonant compensation network as the optimization objective. The process of optimizing the capacitor parameters of the resonant compensation network with the goal of minimizing the overall capacitance deviation tolerance of the resonant compensation network includes: establishing a set of preset capacitance deviation values ​​for each capacitor in the resonant compensation network; selecting any one preset capacitance deviation value from each set to form multiple sets of preset capacitance deviation values ​​for the resonant compensation network; for each set of preset capacitance deviation values, calculating the extreme values ​​of output voltage, power factor, voltage of each capacitor, and transmission efficiency variation within a preset adjustment range for each capacitor's preset capacitance deviation value; calculating the evaluation index value of the overall capacitance deviation tolerance of the resonant compensation network based on the extreme values ​​and their corresponding preset weight values; and calculating the design value of the capacitor of the resonant compensation network based on the preset capacitance deviation values ​​of the set of resonant compensation networks corresponding to the extreme value with the minimum evaluation index value. The process of controlling the inverter frequency using a frequency tracking method based on sensitivity analysis results obtained before system operation includes: before system operation, analyzing the impact of the capacitance deviation value of each capacitor in the resonant compensation network on the system output to obtain a sensitivity index value for the capacitance deviation value of each capacitor; identifying the capacitor with the largest sensitivity index value as the most sensitive factor, thus the capacitor with the largest sensitivity index value is the most sensitive capacitor; during system operation, using a frequency tracking strategy, maintaining the frequency at the frequency that makes the capacitance deviation of the most sensitive capacitor zero.

2. The parameter optimization method for a wireless power transmission system according to claim 1, characterized in that, The process of controlling the frequency of the inverter using a frequency tracking method based on sensitivity analysis further includes: The variance-based Sobol sensitivity analysis method is used to analyze the influence of the capacitance deviation value of each capacitor in the resonant compensation network on the system output, and the first-order effect index value of the capacitance deviation value of each capacitor is obtained. The first-order effect index value is the sensitivity index value.

3. The parameter optimization method for a wireless power transmission system according to claim 1, characterized in that, The process of controlling the frequency of the inverter with the goal of minimizing the overall capacitance deviation tolerance of the resonant compensation network includes: Obtain the real-time capacitance value of each capacitor in the resonant compensation network; based on the real-time capacitance value of each capacitor and the electrical information parameters of the wireless power transmission system, obtain the relationship expression between the real-time evaluation index of the overall capacitance deviation tolerance of the resonant compensation network and the operating frequency. Using an optimization algorithm, the operating frequency is calculated to ensure that the output voltage, power factor, voltage of each capacitor, and transmission efficiency changes are within a preset range, as well as to optimize the real-time evaluation index of the overall capacitor deviation tolerance. The inverter frequency is adjusted to the calculated optimal operating frequency.

4. The parameter optimization method for a wireless power transmission system according to claim 3, characterized in that, When the parameter optimization method only involves controlling the frequency of the inverter, the design value of the capacitor is an ideal value.

5. A parameter optimization system for a wireless power transmission system, characterized in that, Based on the parameter optimization method for a wireless power transmission system according to any one of claims 1-4, the wireless power transmission system includes an inverter, a resonant compensation network, and a rectifier connected in sequence, and the system includes: The parameter optimization module is used to optimize the capacitance parameters of the resonant compensation network before the system is running, with the goal of minimizing the overall capacitance deviation tolerance of the resonant compensation network. The frequency control module is used to control the frequency of the inverter during system operation by applying a frequency tracking method based on the sensitivity analysis results obtained before the system operation or by minimizing the overall capacitance deviation tolerance of the resonant compensation network as the optimization objective.

6. A computer device, characterized in that, include: At least one processor, and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to cause the at least one processor to perform the parameter optimization method for the wireless power transmission system according to any one of claims 1-4.

7. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing the computer to perform the parameter optimization method for the wireless power transmission system according to any one of claims 1-4.

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