Method and device for calculating parasitic resistance of coil of wireless power transmission system

Abstract

The application relates to the wireless power transmission technical field, and provides a wireless power transmission system coil parasitic resistance calculation method and device. The method comprises the following steps: acquiring preset output power and initial coil parasitic resistance of a wireless power transmission system; determining an initial load equivalent resistance according to the preset output power, the initial coil parasitic resistance and a preset load equivalent resistance calculation formula of the wireless power transmission system, and determining an initial loop current according to the initial load equivalent resistance; and optimizing and iterating the initial coil parasitic resistance according to an iteration algorithm combined with a preset damping coefficient and the initial loop current, so as to obtain a target coil parasitic resistance. The wireless power transmission system coil parasitic resistance calculation method and device provided by the application improve the efficiency and precision of coil parasitic resistance calculation.

Description

Technical Field

[0001] This application relates to the field of wireless power transmission technology, and in particular to a method and apparatus for calculating the parasitic resistance of a coil in a wireless power transmission system. Background Technology

[0002] Series-Series (SS) wireless power transfer systems are widely used in smart home appliances, implantable medical devices, and wearable products due to their simple structure, compact size, and convenient control. However, the engineering design of SS wireless power transfer systems typically requires precise circuit parameter calculations and optimization based on boundary conditions such as the system's maximum output power, wireless transmission distance, and input voltage.

[0003] However, in the engineering design of existing SS-type wireless power transfer systems, the accurate determination of coil parasitic resistance faces significant challenges. On one hand, the loop currents on the primary and secondary sides are strongly coupled with the parasitic resistance in the magnetic field environment of the coil, making the circuit equations sensitive to changes in coil resistance, often leading to non-convergence in the calculated parasitic resistance. On the other hand, existing calculation methods mostly employ empirical or conventional iterative methods to estimate the coil's parasitic resistance. Empirical methods have low accuracy and are insufficient for high-performance design requirements; while conventional iterative methods typically involve nested calculations of load parameter scanning and field-circuit coupling, resulting in massive computational loads, long processing times, and extreme sensitivity to initial value selection. This can easily lead to non-convergence in the iteration, resulting in significant errors in the parasitic resistance calculations and posing a risk of misjudging system efficiency and maximum power.

[0004] Therefore, it is of great significance to address the problems of large computational load, heavy reliance on experience, and difficulty in convergence in existing technologies, and to improve the efficiency and accuracy of parasitic resistance calculation. Summary of the Invention

[0005] This application provides a method and apparatus for calculating the parasitic resistance of coils in a wireless power transmission system, which solves the problems of large computational load, heavy reliance on experience, and difficulty in convergence in the prior art, thereby improving the efficiency and accuracy of parasitic resistance calculation.

[0006] In a first aspect, this application provides a method for calculating the parasitic resistance of a coil in a wireless power transmission system, the method comprising: Obtain the preset output power and initial coil parasitic resistance of the wireless power transmission system; The initial load equivalent resistance is determined based on the preset output power, initial coil parasitic resistance, and preset load equivalent resistance calculation formula of the wireless power transmission system, and the initial loop current is determined based on the initial load equivalent resistance. Based on the iterative algorithm combining the preset damping coefficient and the initial loop current, the parasitic resistance of the initial coil is optimized iteratively to obtain the parasitic resistance of the target coil; Wherein, the initial coil parasitic resistance is the DC resistance of the coil of the wireless power transmission system; The preset formula for calculating the equivalent load resistance is used to characterize the mapping relationship between the equivalent load resistance of the wireless power transmission system and the output power and coil parasitic resistance. The preset damping coefficient is used to update the parasitic resistance of the coil during the iteration process.

[0007] Optionally, according to the method for calculating the parasitic resistance of a wireless power transmission system coil in this application, the step of optimizing and iterating the initial coil parasitic resistance based on an iterative algorithm combining a preset damping coefficient and the initial loop current to obtain the target coil parasitic resistance includes: Repeat the iterative steps until the preset convergence condition is met, and use the parasitic resistance obtained in the last iteration as the parasitic resistance of the target coil. The iterative steps include: The loop current from the previous iteration is input into the preset magnetic field calculation model to obtain the magnetic field distribution for the current iteration; Based on the magnetic field distribution of this iteration and the loop current of the previous iteration, determine the candidate parasitic resistance for this iteration; The parasitic resistance of this iteration is obtained based on the parasitic resistance of the previous iteration, the preset damping coefficient, and the candidate parasitic resistance of this iteration. Based on the preset output power, the parasitic resistance of this iteration, and the preset load equivalent resistance calculation formula, the load equivalent resistance of this iteration is determined, and the loop current of this iteration is determined based on the load equivalent resistance of this iteration. The preset convergence condition is that the error between the loop current of the current iteration and the loop current of the previous iteration is less than a preset error value. The loop current from the previous iteration used in the first iteration is the initial loop current; The parasitic resistance of the previous iteration used in the first iteration is the parasitic resistance of the initial coil.

[0008] Optionally, according to the method for calculating the parasitic resistance of a wireless power transmission system coil in this application, the step of obtaining the parasitic resistance of the current iteration based on the parasitic resistance of the previous iteration, the preset damping coefficient, and the candidate parasitic resistance of the current iteration includes: Obtain the difference between the candidate parasitic resistance in the current iteration and the parasitic resistance in the previous iteration; Based on the difference value and the preset damping coefficient, the parasitic resistance of the previous iteration is updated, and the parasitic resistance of the current iteration is obtained based on the updated parasitic resistance of the previous iteration.

[0009] Optionally, according to the method for calculating the parasitic resistance of the coil in the wireless power transmission system of this application, the preset error value is less than the product of the preset damping coefficient and the preset coefficient.

[0010] Optionally, according to the method for calculating the parasitic resistance of a wireless power transmission system coil in this application, determining the initial load equivalent resistance based on the preset output power of the wireless power transmission system, the initial coil parasitic resistance, and a preset formula for calculating the load equivalent resistance includes: To obtain the input voltage, operating frequency, and mutual inductance value of the wireless power transmission system; The initial load equivalent resistance is determined based on the preset output power, initial coil parasitic resistance, input voltage, operating frequency, mutual inductance value, and the preset load equivalent resistance calculation formula.

[0011] Optionally, according to the method for calculating the parasitic resistance of a wireless power transmission system coil in this application, the wireless power transmission system includes at least one of a transmitting coil and a receiving coil.

[0012] Optionally, according to the method for calculating the parasitic resistance of the coil in the wireless power transmission system of this application, the preset formula for calculating the equivalent resistance of the load is: ; in, Indicates the equivalent resistance of the load; Indicates the preset output power; This represents the parasitic resistance of the transmitting coil; This represents the parasitic resistance of the receiving coil; Indicates the input voltage; Indicates the operating frequency; This represents the mutual inductance between the transmitting coil and the receiving coil.

[0013] Secondly, this application also provides a device for calculating the parasitic resistance of a coil in a wireless power transmission system, the device comprising: The acquisition module is used to acquire the preset output power and initial coil parasitic resistance of the wireless power transmission system; The determination module is used to determine the initial load equivalent resistance based on the preset output power of the wireless power transmission system, the initial coil parasitic resistance, and the preset load equivalent resistance calculation formula, and to determine the initial loop current based on the initial load equivalent resistance. The optimization module is used to perform iterative optimization on the initial coil parasitic resistance based on an iterative algorithm that combines a preset damping coefficient and the initial loop current, so as to obtain the target coil parasitic resistance. Wherein, the initial coil parasitic resistance is the DC resistance of the coil of the wireless power transmission system; The preset formula for calculating the equivalent load resistance is used to characterize the mapping relationship between the equivalent load resistance of the wireless power transmission system and the output power and coil parasitic resistance. The preset damping coefficient is used to update the parasitic resistance of the coil during the iteration process.

[0014] Thirdly, this application provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method for calculating the parasitic resistance of a wireless power transmission system coil as described in the first aspect above.

[0015] Fourthly, this application provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for calculating the parasitic resistance of a coil in a wireless power transmission system as described in the first aspect above.

[0016] The method and apparatus for calculating the parasitic resistance of a wireless power transmission system coil provided in this application directly solves for the initial load equivalent resistance and the corresponding loop current by substituting the preset output power and initial coil parasitic resistance into the load equivalent resistance calculation formula. This avoids repeated iterations of the load resistance, saves design resources, and significantly reduces the enormous computational load and time consumption caused by traditional experience-based global parameter scanning. By adding a preset damping coefficient to the iterative calculation starting from the initial loop current to optimize the target coil parasitic resistance, this method and apparatus solves the problems of heavy reliance on experience and difficulty in convergence in existing technologies, thus improving the efficiency and accuracy of parasitic resistance calculation. Attached Figure Description

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

[0018] Figure 1 This is an example circuit model diagram of an existing SS-type wireless power transmission system provided in this application.

[0019] Figure 2 This is a flowchart illustrating the method for calculating the parasitic resistance of a coil in a wireless power transmission system provided in this application.

[0020] Figure 3 This is an example diagram of the method for calculating the parasitic resistance of the coil in the wireless power transmission system provided in this application.

[0021] Figure 4 This is a schematic diagram of the structure of the wireless power transmission system coil parasitic resistance calculation device provided in this application.

[0022] Figure 5 This is a schematic diagram of the structure of the electronic device provided in this application. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] Figure 1 This is an example circuit model diagram of an existing SS-type wireless power transfer system provided in this application, such as... Figure 1 As shown, This indicates the capacitance value of the primary-side compensation capacitor; This indicates the capacitance value of the secondary-side compensation capacitor; This indicates the inductance value of the transmitting coil; This indicates the inductance value of the receiving coil; This represents the parasitic resistance of the transmitting coil; This represents the parasitic resistance of the receiving coil; This represents the mutual inductance between the transmitting coil and the receiving coil; Indicates the equivalent resistance of the load; Indicates the input voltage; This represents the loop current of the transmitting coil; This represents the loop current of the receiving coil.

[0025] Figure 2 This is a flowchart illustrating the method for calculating the parasitic resistance of the coil in the wireless power transmission system provided in this application, as shown below. Figure 2 As shown, the method may include: Step 210: Obtain the preset output power and initial coil parasitic resistance of the wireless power transmission system; Step 220: Determine the initial load equivalent resistance based on the preset output power of the wireless power transmission system, the initial coil parasitic resistance, and the preset load equivalent resistance calculation formula, and determine the initial loop current based on the initial load equivalent resistance. Step 230: Based on the iterative algorithm combining the preset damping coefficient and the initial loop current, optimize and iterate the initial coil parasitic resistance to obtain the target coil parasitic resistance; Wherein, the initial coil parasitic resistance is the DC resistance of the coil in the wireless power transmission system; The preset formula for calculating the equivalent load resistance is used to characterize the mapping relationship between the equivalent load resistance of a wireless power transmission system and its output power and coil parasitic resistance. The preset damping coefficient is used to update the parasitic resistance of the coil during the iteration process.

[0026] In one embodiment, the wireless power transmission system includes at least one of a transmitting coil and a receiving coil.

[0027] It should be noted that the execution subject of the above-mentioned method for calculating the parasitic resistance of the coil in a wireless power transmission system can be a computer device. This computer device can be a personal computer, server, workstation, laptop, dedicated computing device, or electronic terminal loaded with wireless power transmission system design and simulation software, etc., and this application does not specifically limit its use.

[0028] It is understood that the wireless power transfer system involved in this application includes at least one of a transmitting coil and a receiving coil. This means that the method for calculating the parasitic resistance of the coils in the wireless power transfer system provided in this application is applicable not only to the calculation of the parasitic resistance of a single-sided coil, but also to the joint calculation of the parasitic resistance of both primary and secondary coils. For example, an iterative algorithm can be performed on the transmitting coil (i.e., the primary coil) to obtain its target coil parasitic resistance; an iterative algorithm can also be performed on the receiving coil (i.e., the secondary coil) to obtain its target coil parasitic resistance; or, the transmitting coil and the receiving coil can be treated as a whole calculation object, and the target coil parasitic resistances of both can be derived and obtained simultaneously in the damping iterative calculation.

[0029] It should be further noted that, depending on the computational object of the wireless power transmission system, the specific physical orientation of the various computational parameters involved in the subsequent calculation steps of this application (such as the initial coil parasitic resistance, the target coil parasitic resistance, the initial load equivalent resistance, the initial loop current, etc.) will also be adaptively adjusted. For example, when the transmitting coil is the computational object, "target coil parasitic resistance" specifically refers to the target coil parasitic resistance of the transmitting coil, and correspondingly, the "initial loop current" and other related parameters also refer to the parameters of the transmitting coil and its primary loop. Furthermore, when the transmitting coil and the receiving coil are considered as a whole computational object, the above parameters simultaneously characterize the corresponding physical quantities of the primary and secondary loops. Based on this adaptive matching mechanism, the algorithm framework of this application has high universality, which will not be elaborated upon in the following steps.

[0030] Specifically, a wireless power transmission system coil refers to an electromagnetic coupling element used in a wireless power transmission system. For example, a wireless power transmission system coil can be a coil in an SS (Series-Series) type wireless power transmission system, a coil in an SP (Series-Parallel) type wireless power transmission system, a coil in a PS (Parallel-Series) type wireless power transmission system, or a coil in a PP (Parallel-Parallel) type wireless power transmission system. This application does not impose specific limitations on this.

[0031] The preset output power refers to the power boundary conditions given at the initial engineering design stage of a wireless power transmission system. For example, since loads with charging or driving functions generally have constant power characteristics, the maximum output power of the wireless power transmission system can be used as the preset output power. Alternatively, the preset output power can also be the rated output power, the average output power, or the transient output power dynamically set according to the battery charging curve for a specific period. This application does not specifically limit this.

[0032] The preset formula for calculating the equivalent load resistance can directly reflect the mapping relationship between the equivalent load resistance and circuit parameters such as preset output power and coil parasitic resistance, replacing the time-consuming global parameter scanning process in traditional design.

[0033] The preset damping coefficient refers to a smoothing constraint factor introduced to control the parameter update step size and suppress system oscillations caused by rapid numerical changes. The preset damping coefficient can be a fixed value, between 0.1 and 0.5; it can also be a coefficient that dynamically and adaptively decays with increasing iteration count or error changes; or it can be two weighting factors with different dimensions configured independently for the transmitting and receiving coils. This application does not impose specific limitations on this.

[0034] The parasitic resistance of the target coil refers to the parasitic resistance that meets the error accuracy requirements after convergence of the iterative algorithm combined with the preset damping coefficient.

[0035] Specifically, in step 210, the preset output power of the wireless power transmission system is obtained based on the preset boundary conditions during the engineering design of the wireless power transmission system. Simultaneously, the physical property parameters of the conductors are obtained, the DC resistance of the corresponding coil is calculated, and this DC resistance is used as the initial parasitic resistance of the coil. The calculation process of the DC resistance is shown in formula (1): Formula (1) in, Indicates DC resistance. Represents the resistivity of a metal. Indicates the length of the conductor. This represents the conductive cross-sectional area.

[0036] In step 220, the preset output power and initial coil parasitic resistance of the wireless power transmission system are substituted into the pre-constructed preset load equivalent resistance calculation formula to calculate the initial load equivalent resistance. Subsequently, the obtained initial load equivalent resistance is substituted into the loop equation, and the corresponding initial loop current is determined according to the loop equation.

[0037] Understandably, according to Figure 1 The loop model shown has the loop equations as shown in formula (2): Formula (2) in, Indicates the input voltage. This indicates the inductance value of the transmitting coil. This indicates the capacitance value of the primary-side compensation capacitor. This represents the parasitic resistance of the transmitting coil. This represents the loop current of the transmitting coil. This represents the mutual inductance between the transmitting and receiving coils. This represents the loop current of the receiving coil. This indicates the inductance value of the receiving coil. This indicates the capacitance value of the secondary-side compensation capacitor. Indicates the equivalent resistance of the load. This represents the parasitic resistance of the receiving coil. Represents the imaginary unit. Indicates the operating frequency.

[0038] By solving formula (2), the analytical expression for calculating the loop current can be derived, thus obtaining the initial loop current. The analytical expression for calculating the loop current is shown in formula (3): Formula (3) Alternatively, the output power of the wireless power transmission system can be obtained according to formulas (2) and (3), as shown in formula (4): Formula (4) in, This represents the resonant angular frequency of a wireless power transmission system.

[0039] Understandably, the load of a wireless power transfer system is often a circuit with lithium battery charging or driving functions. The equivalent impedance of these circuits varies with operating conditions, but they generally have constant power characteristics, and the maximum power is fixed. Therefore, the maximum output power of the wireless power transfer coil is used as a preset boundary when designing a wireless power transfer system.

[0040] In step 230, the initial loop current obtained in step 220 is used as the starting condition for the iterative algorithm. Considering that under certain operating conditions (especially in low-coupling operating regions), the loop equation is extremely sensitive to changes in coil resistance, directly using the unprocessed parasitic coil resistance for the next round of iterative calculations often leads to numerical oscillations or even divergent results. Therefore, a smoothing intervention is performed by pre-setting a damping coefficient to optimize the initial parasitic coil resistance through iterative calculation, thereby obtaining the target parasitic coil resistance.

[0041] The method for calculating the parasitic resistance of a wireless power transmission system coil provided in this application directly solves for the initial load equivalent resistance and the corresponding initial loop current by substituting the preset output power and initial coil parasitic resistance into the load equivalent resistance calculation formula. This method avoids repeated iterations of the load resistance, saves design resources, and significantly reduces the enormous computational load and time consumption caused by traditional global parameter scanning based on experience. By adding a preset damping coefficient to the iterative calculation starting from the initial loop current to optimize the iteration to obtain the target coil parasitic resistance, this method solves the problems of heavy reliance on experience and difficulty in convergence in existing technologies, thus improving the efficiency and accuracy of coil parasitic resistance calculation.

[0042] In one embodiment, the initial coil parasitic resistance is optimized iteratively based on an iterative algorithm incorporating a preset damping coefficient and the initial loop current to obtain the target coil parasitic resistance, including: Repeat the iterative steps until the preset convergence condition is met, and use the parasitic resistance obtained in the last iteration as the parasitic resistance of the target coil. The iterative steps include: The loop current from the previous iteration is input into the preset magnetic field calculation model to obtain the magnetic field distribution for the current iteration; Based on the magnetic field distribution of this iteration and the loop current of the previous iteration, the candidate parasitic resistances for this iteration are determined; Based on the parasitic resistance of the previous iteration, the preset damping coefficient, and the candidate parasitic resistance of this iteration, the parasitic resistance of this iteration is obtained; Based on the preset output power, the parasitic resistance of this iteration, and the preset formula for calculating the equivalent load resistance, determine the equivalent load resistance of this iteration, and determine the loop current of this iteration based on the equivalent load resistance of this iteration. The preset convergence condition is that the error between the loop current of the current iteration and the loop current of the previous iteration is less than the preset error value. The loop current from the previous iteration used in the first iteration is the initial loop current; The parasitic resistance from the previous iteration used in the first iteration is the parasitic resistance of the initial coil.

[0043] Understandably, the resistance generated by the proximity effect is related to the magnetic field distribution, which is produced by the transmitting and receiving coils under the excitation of the transmitting and receiving loop currents. Changes in coil resistance cause changes in loop current, and conversely, changes in loop current cause changes in coil resistance by affecting the magnetic field distribution. Because the relationship between coil resistance and loop current is highly nonlinear, it is impossible to decouple them analytically. In engineering design, iterative algorithms are required for solving the problem.

[0044] Specifically, the preset magnetic field calculation model refers to a simulation analysis tool or mathematical model used to simulate and calculate the spatial distribution of electromagnetic fields. For example, the preset magnetic field calculation model could be the Maxwell magnetic field calculation model or the Comsol magnetic field calculation model. This application does not impose a specific limitation on this.

[0045] The candidate parasitic resistances in this iteration refer to the theoretical parasitic resistance values ​​calculated according to the physical formula of the AC proximity effect. These candidate parasitic resistances have not yet undergone smoothing with a preset damping coefficient; direct use of them could easily lead to calculation divergence.

[0046] The preset error value is a threshold set according to engineering accuracy requirements. For example, it can be set as a fixed constant based on historical records; it can also be adjusted according to the damping coefficient; or it can be dynamically adjusted according to actual iteration. This application does not impose specific limitations on this.

[0047] Optionally, in the first iteration, the initial loop current is used as the loop current of the previous iteration used in the first iteration, and the initial coil parasitic resistance is used as the parasitic resistance of the previous iteration used in the first iteration.

[0048] Next, the iteration step begins, where the loop current from the previous iteration is input into the preset magnetic field calculation model. Upon receiving the loop current, the preset magnetic field calculation model performs electromagnetic field calculations to obtain the magnetic field distribution for the current iteration.

[0049] It is understandable that the parasitic resistance of a wireless power transfer system coil includes both DC and AC resistance, with the AC resistance comprising the resistance caused by the skin effect and the resistance caused by the proximity effect. Wireless power transfer system coils are typically wound with Ritz wire, whose single-strand diameter is much smaller than the skin depth, so the resistance increment caused by the skin effect has a negligible impact. Therefore, the resistance caused by the skin effect can be ignored. The resistance caused by the proximity effect can be calculated using formula (5): Formula (5) in, This represents the resistance caused by the proximity effect. This represents the trajectory of the centerline of the conductor in the coil. Indicates the number of coil turns. hour The magnitude of the magnetic field strength at the location, This represents the loop current flowing through the coil. This represents a frequency-dependent scaling factor. This indicates the structural parameters associated with the coil conductor.

[0050] Therefore, according to formulas (1) and (5), the parasitic resistance of the coil in the wireless power transmission system can be calculated, as shown in formula (6): Formula (6) in, This represents the parasitic resistance of the coil in a wireless power transmission system.

[0051] Subsequently, based on the magnetic field distribution of this iteration, the loop current of the previous iteration, and formula (6), the candidate parasitic resistances for this iteration are determined.

[0052] After obtaining the candidate parasitic resistances for this round of iteration, in order to avoid non-convergence caused by sudden parameter changes, the candidate parasitic resistances for this round of iteration are updated using the preset damping coefficient and the parasitic resistances of the previous round of iteration, thus obtaining the parasitic resistances for this round of iteration.

[0053] Furthermore, based on the preset output power, the parasitic resistance of this iteration, and the preset formula for calculating the equivalent resistance of the load, the equivalent resistance of the load in this iteration is obtained, and the equivalent resistance of the load in this iteration is substituted into formula (3) to calculate the current of the loop in this iteration.

[0054] Finally, based on the loop current of this iteration and the loop current of the previous iteration, the error value between the two is calculated, and it is determined whether the error value is less than the preset error value.

[0055] If the error value is greater than or equal to the preset error value, it indicates that the iteration process has not yet converged. The loop current of this iteration is taken as the "loop current of the previous iteration" for the next iteration, and the parasitic resistance of this iteration is taken as the "parasitic resistance of the previous iteration" for the next iteration. The iteration number is incremented to continue the next iteration.

[0056] If the error value is less than the preset error value, it indicates that the iteration process has converged sufficiently. At this point, the iteration step is stopped, and the parasitic resistance obtained in the last iteration is output as the final target coil parasitic resistance, thus completing the high-precision parasitic resistance calculation.

[0057] The method for calculating the parasitic resistance of a wireless power transmission system coil provided in this application obtains the target coil parasitic resistance by inputting the loop current of the previous iteration into a preset magnetic field calculation model and optimizing the initial coil parasitic resistance in combination with a preset damping coefficient. This method effectively avoids the problems of numerical oscillation and non-convergence of calculation results during the calculation process, thereby significantly reducing the calculation time while ensuring the efficiency and high accuracy of the target coil parasitic resistance calculation.

[0058] In one embodiment, the parasitic resistance of the current iteration is obtained based on the parasitic resistance of the previous iteration, a preset damping coefficient, and candidate parasitic resistances of the current iteration, including: Obtain the difference between the candidate parasitic resistance in this iteration and the parasitic resistance in the previous iteration; Based on the difference value and the preset damping coefficient, the parasitic resistance of the previous iteration is updated, and the parasitic resistance of the current iteration is obtained based on the updated parasitic resistance of the previous iteration.

[0059] It is understandable that, under conditions of low coupling in the transmit and receive paths, the circuit parameters affect the parasitic resistance of the transmitting coil. Parasitic resistance of the receiving coil Very sensitive, when and Rapid changes can cause oscillations in the iterative process, leading to non-convergence. Therefore, the candidate parasitic resistance in the current iteration cannot be directly used as the final parasitic resistance calculation result. Instead, it needs to be damped to ensure convergence of the iterative process.

[0060] Optionally, during the iteration process, the candidate parasitic resistance of the current iteration and the parasitic resistance of the previous iteration are first obtained, and the difference between the two is calculated. This difference reflects the resistance disturbance caused by changes in the magnetic field environment.

[0061] Subsequently, based on the obtained difference value and the preset damping coefficient, the parasitic resistance of the previous iteration is updated, and the parasitic resistance of the current iteration is obtained based on the updated parasitic resistance of the previous iteration. For example, the difference value is multiplied by the preset damping coefficient to obtain a suppressed resistance change increment, and then the resistance change increment is added to the parasitic resistance of the previous iteration, thereby obtaining the parasitic resistance of the current iteration based on the updated parasitic resistance of the previous iteration.

[0062] Optionally, the method for calculating the parasitic resistance of a wireless power transmission system coil provided in this application is applicable not only to the calculation of the parasitic resistance of a single-sided coil, but also to the joint calculation of the parasitic resistance of both primary and secondary coils. For example, an iterative algorithm can be performed on the transmitting coil (i.e., the primary coil) to obtain the parasitic resistance of the current iteration; an iterative algorithm can also be performed on the receiving coil (i.e., the secondary coil) to obtain the parasitic resistance of the current iteration; or, the transmitting coil and the receiving coil can be treated as a whole calculation object, and their parasitic resistances of the current iteration can be derived and obtained simultaneously in the damping iterative calculation. When the transmitting coil and the receiving coil are treated as a whole calculation object, the process of simultaneously deriving and obtaining their parasitic resistances of the current iteration is shown in formula (7): Formula (7) in, Indicates the number of iterations in this round. Indicates the number of the previous iteration. This represents the parasitic resistance of the transmitting coil in this iteration. This represents the parasitic resistance of the transmitting coil in the previous iteration. This represents the parasitic resistance of the receiving coil in this iteration. This represents the parasitic resistance of the receiving coil in the previous iteration. This indicates the preset damping coefficient.

[0063] The method for calculating the parasitic resistance of a wireless power transmission system coil provided in this application obtains the difference between the candidate parasitic resistance of the current iteration and the parasitic resistance of the previous iteration, updates the parasitic resistance of the previous iteration based on the difference and a preset damping coefficient, and obtains the parasitic resistance of the current iteration based on the updated parasitic resistance of the previous iteration. This method can effectively control the rate of change of parasitic resistance with the iteration process, avoids the iterative oscillation and non-convergence problems caused by directly using theoretical calculation values, and thus significantly improves the stability and reliability of the calculation process of the parasitic resistance of the wireless power transmission system coil.

[0064] In one embodiment, the preset error value is less than the product of the preset damping coefficient and the preset coefficient.

[0065] Specifically, the preset coefficient refers to a proportional constant used to establish a positive correlation between the preset error value and the preset damping coefficient. For example, the preset coefficient can be set to 0.1; it can also be dynamically adjusted according to the specific circuit topology characteristics. This application does not impose specific limitations on it.

[0066] Understandably, in the actual iteration process, if the preset damping coefficient is too large, it will not be able to suppress the sudden change in resistance, which will easily lead to non-convergence of the iteration and failure to output the calculation results; if the preset damping coefficient is too small, it will lead to the resistance update step size being extremely small, making the iteration too slow, and may even converge to the wrong point.

[0067] Specifically, a corresponding preset error value is configured based on the determined preset damping coefficient. The preset error value and the preset damping coefficient are positively correlated. When the preset damping coefficient decreases, the update weight of the candidate parasitic resistance in each round decreases accordingly, resulting in a suppression of the change in loop current calculated between consecutive rounds. Therefore, the preset error value needs to be reduced accordingly. Otherwise, the iteration process may easily converge to an error value.

[0068] Therefore, to obtain sufficiently accurate iterative results, it is necessary to ensure that the preset error value is less than the product of the preset damping coefficient and the preset coefficient. The relationship between the preset error value and the preset damping coefficient can be shown in formula (8): Formula (8) in, This represents the preset error value, and 0.1 represents the preset coefficient.

[0069] The method for calculating the parasitic resistance of a wireless power transmission system coil provided in this application establishes an adaptive linkage mechanism between the convergence threshold and the preset damping coefficient during the iteration process by ensuring that the preset error value is less than the product of the preset damping coefficient and the preset coefficient. This effectively avoids the problem of the iterative algorithm converging to the wrong node due to overly lenient convergence conditions when the damping coefficient is small. Thus, while ensuring a smooth and oscillating iteration process, it maximizes the accuracy and reliability of the parasitic resistance calculation results of the target coil.

[0070] In one embodiment, the initial load equivalent resistance is determined based on the preset output power of the wireless power transmission system, the initial coil parasitic resistance, and a preset formula for calculating the load equivalent resistance, including: To obtain the input voltage, operating frequency, and mutual inductance value of the wireless power transmission system; The initial load equivalent resistance is determined based on the preset output power, initial coil parasitic resistance, input voltage, operating frequency, mutual inductance value, and the preset load equivalent resistance calculation formula.

[0071] In one embodiment, the preset formula for calculating the equivalent resistance of the load is: ; in, Indicates the equivalent resistance of the load. Indicates the preset output power. This represents the parasitic resistance of the transmitting coil. This represents the parasitic resistance of the receiving coil. Indicates the input voltage. Indicates the operating frequency. This represents the mutual inductance between the transmitting coil and the receiving coil.

[0072] Understandably, the relationship between the system's output power and the load's equivalent resistance is complex in circuit equations. Current system design methods require a global parameter scan of the load's equivalent resistance based on experience; that is, calculating the relationship between the load's equivalent resistance, mutual inductance, and output power from small to large within a specific range, and then selecting a suitable dataset as the system optimization dataset. This method is computationally intensive, requiring a long time for a single design, and is not conducive to rapid system design and optimization iterations.

[0073] Specifically, the input voltage refers to the power supply voltage provided to the transmitter of the wireless power transmission system. For example, the input voltage could be the DC bus voltage at the front end of a converter. This application does not specifically limit this.

[0074] The operating frequency can be determined based on the resonant frequency of the wireless power transmission system design. This application does not impose specific limitations on this.

[0075] Mutual inductance refers to an inherent parameter characterizing the magnetic field coupling strength between the transmitting and receiving coils. For example, mutual inductance can be pre-calculated using finite element electromagnetic simulation software. This application does not impose specific limitations on it.

[0076] The preset formula for calculating the equivalent load resistance is an analytical formula derived algebraically based on Kirchhoff's laws and loop equations. This preset formula breaks away from the conventional design process of scanning global parameters based on experience, thus enabling the direct solution of the equivalent load resistance.

[0077] Specifically, first, the input voltage, operating frequency, and mutual inductance of the wireless power transfer system are obtained. In the engineering design of wireless power transfer systems, the circuit typically exhibits constant power characteristics, and the maximum output power is determined. Therefore, the input voltage, operating frequency, mutual inductance, and maximum output power together constitute the known boundary conditions of the wireless power transfer system.

[0078] By analyzing formulas (2), (3), and (4), the preset load equivalent resistance calculation formula can be derived, explicitly expressing the previously implicit preset output power in the preset load equivalent resistance calculation formula. Therefore, various parameters can be substituted into the preset load equivalent resistance calculation formula without performing any global parameter scanning steps, thereby obtaining the load equivalent resistance and providing an accurate input benchmark for subsequent iterative algorithms.

[0079] The method for calculating the parasitic resistance of the coil in a wireless power transfer system provided in this application obtains the input voltage, operating frequency, and mutual inductance value, and determines the equivalent load resistance using an explicit formula for calculating the equivalent load resistance. This method can accurately capture the analytical mapping relationship between output power and load resistance, completely avoiding the huge amount of calculation and serious time loss caused by the need to perform a global scan of load parameters from small to large within a specific range in the prior art. This greatly improves the calculation speed and optimization iteration efficiency of wireless power transfer system design.

[0080] To facilitate a clearer understanding of the technical solutions of the various embodiments of this application, further explanation is provided.

[0081] Figure 3 This is an example diagram of the method for calculating the parasitic resistance of the coil in a wireless power transmission system provided in this application, as shown below. Figure 3 As shown, in step 3001, parameter initialization is performed, and the number of iterations is set to 0.

[0082] In step 3002, the DC resistance of the wireless power transfer system coil is used as the initial coil parasitic resistance. For example, it can be... This represents the DC resistance of the transmitting coil in its initial state. This represents the DC resistance of the receiving coil in its initial state.

[0083] In steps 3003 and 3004, the initial load equivalent resistance is determined based on the preset output power of the wireless power transmission system and the initial coil parasitic resistance. The initial load equivalent resistance is then substituted into formula (3) to determine the initial loop current. The initial loop current includes the initial loop current of the transmitting coil and the initial loop current of the receiving coil.

[0084] In step 3005, the loop iteration begins, and the iteration count is updated to... .

[0085] In steps 3006 to 3008, the loop current of the previous iteration is input into the preset magnetic field calculation model to obtain the magnetic field distribution of the current iteration.

[0086] Based on formula (6) and the parasitic resistance of the previous iteration, calculate the candidate parasitic resistance of this iteration under the magnetic field distribution of this iteration. Among them, the candidate parasitic resistance of this iteration includes the candidate parasitic resistance of the transmitting coil and the candidate parasitic resistance of the receiving coil.

[0087] To avoid oscillations in the circuit equations, the candidate parasitic resistances for this round are damped according to formula (7) and combined with a preset damping coefficient to obtain the parasitic resistances for this round of iterations. The parasitic resistances for this round of iterations include the parasitic resistances of the transmitting coil and the receiving coil.

[0088] In step 3009, the load equivalent resistance for this iteration is determined based on the preset output power, the parasitic resistance of this iteration, and the preset load equivalent resistance calculation formula.

[0089] In step 3010, the error value between the loop current of the current iteration and the loop current of the previous iteration is obtained. This error value includes the error value of the transmitting coil and the error value of the receiving coil.

[0090] Subsequently, a convergence condition check is performed. If the error values ​​of the transmitting coil and the receiving coil are greater than or equal to the preset error values, it indicates that the field-path coupling has not yet reached a steady state, and the process returns to step 3005 to continue the next iteration.

[0091] If the error values ​​of both the transmitting coil and the receiving coil are less than the preset error values, proceed to step 3011.

[0092] In step 3011, the iteration ends, and the parasitic resistance obtained in the last iteration is output as the parasitic resistance of the target coil.

[0093] The following describes the device for calculating the parasitic resistance of a wireless power transmission system coil provided in this application. The device described below can be referred to in correspondence with the method described above for calculating the parasitic resistance of a wireless power transmission system coil, and can achieve the same technical effect. Therefore, it will not be described again here.

[0094] Figure 4 This is a schematic diagram of the structure of the wireless power transmission system coil parasitic resistance calculation device provided in this application, as shown below. Figure 4 As shown, the device may include: The acquisition module 410 is used to acquire the preset output power and initial coil parasitic resistance of the wireless power transmission system; The determining module 420 is used to determine the initial load equivalent resistance based on the preset output power of the wireless power transmission system, the initial coil parasitic resistance, and the preset load equivalent resistance calculation formula, and to determine the initial loop current based on the initial load equivalent resistance. The optimization module 430 is used to perform optimization iteration on the initial coil parasitic resistance according to the iterative algorithm combining the preset damping coefficient and the initial loop current, so as to obtain the target coil parasitic resistance. Wherein, the initial coil parasitic resistance is the DC resistance of the coil of the wireless power transmission system; The preset formula for calculating the equivalent load resistance is used to characterize the mapping relationship between the equivalent load resistance of the wireless power transmission system and the output power and coil parasitic resistance. The preset damping coefficient is used to update the parasitic resistance of the coil during the iteration process.

[0095] In one embodiment, the optimization module 430 is specifically used for: Repeat the iterative steps until the preset convergence condition is met, and use the parasitic resistance obtained in the last iteration as the parasitic resistance of the target coil. The iterative steps include: The loop current from the previous iteration is input into the preset magnetic field calculation model to obtain the magnetic field distribution for the current iteration; Based on the magnetic field distribution of this iteration and the loop current of the previous iteration, determine the candidate parasitic resistance for this iteration; The parasitic resistance of this iteration is obtained based on the parasitic resistance of the previous iteration, the preset damping coefficient, and the candidate parasitic resistance of this iteration. Based on the preset output power, the parasitic resistance of this iteration, and the preset load equivalent resistance calculation formula, the load equivalent resistance of this iteration is determined, and the loop current of this iteration is determined based on the load equivalent resistance of this iteration. The preset convergence condition is that the error between the loop current of the current iteration and the loop current of the previous iteration is less than a preset error value. The loop current from the previous iteration used in the first iteration is the initial loop current; The parasitic resistance of the previous iteration used in the first iteration is the parasitic resistance of the initial coil.

[0096] In one embodiment, the optimization module 430 is specifically used for: Obtain the difference between the candidate parasitic resistance in the current iteration and the parasitic resistance in the previous iteration; Based on the difference value and the preset damping coefficient, the parasitic resistance of the previous iteration is updated, and the parasitic resistance of the current iteration is obtained based on the updated parasitic resistance of the previous iteration.

[0097] In one embodiment, the preset error value is less than the product of the preset damping coefficient and the preset coefficient.

[0098] In one embodiment, determining the initial load equivalent resistance based on the preset output power of the wireless power transmission system, the initial coil parasitic resistance, and a preset formula for calculating the load equivalent resistance includes: To obtain the input voltage, operating frequency, and mutual inductance value of the wireless power transmission system; The initial load equivalent resistance is determined based on the preset output power, initial coil parasitic resistance, input voltage, operating frequency, mutual inductance value, and the preset load equivalent resistance calculation formula.

[0099] In one embodiment, the wireless power transmission system includes at least one of a transmitting coil and a receiving coil.

[0100] In one embodiment, the preset formula for calculating the equivalent load resistance is: ; in, Indicates the equivalent resistance of the load; Indicates the preset output power; This represents the parasitic resistance of the transmitting coil; This represents the parasitic resistance of the receiving coil; Indicates the input voltage; Indicates the operating frequency; This represents the mutual inductance between the transmitting coil and the receiving coil.

[0101] Figure 5 This is a schematic diagram of the structure of the electronic device provided in this application, such as... Figure 5 As shown, the electronic device may include: a processor 510, a communications interface 520, a memory 530, and a communication bus 540, wherein the processor 510, the communications interface 520, and the memory 530 communicate with each other via the communication bus 540. The processor 510 can call logical instructions in the memory 530 to execute the method for calculating the parasitic resistance of the coil in the wireless power transmission system described in any of the above embodiments, for example including: Obtain the preset output power and initial coil parasitic resistance of the wireless power transmission system; The initial load equivalent resistance is determined based on the preset output power, initial coil parasitic resistance, and preset load equivalent resistance calculation formula of the wireless power transmission system, and the initial loop current is determined based on the initial load equivalent resistance. Based on the iterative algorithm combining the preset damping coefficient and the initial loop current, the parasitic resistance of the initial coil is optimized iteratively to obtain the parasitic resistance of the target coil; Wherein, the initial coil parasitic resistance is the DC resistance of the coil of the wireless power transmission system; The preset formula for calculating the equivalent load resistance is used to characterize the mapping relationship between the equivalent load resistance of the wireless power transmission system and the output power and coil parasitic resistance. The preset damping coefficient is used to update the parasitic resistance of the coil during the iteration process.

[0102] Furthermore, the logical instructions in the aforementioned memory 530 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0103] On the other hand, this application also provides a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, is implemented to perform the method for calculating the parasitic resistance of a coil in a wireless power transmission system provided by the methods described above, the method comprising: Obtain the preset output power and initial coil parasitic resistance of the wireless power transmission system; The initial load equivalent resistance is determined based on the preset output power, initial coil parasitic resistance, and preset load equivalent resistance calculation formula of the wireless power transmission system, and the initial loop current is determined based on the initial load equivalent resistance. Based on the iterative algorithm combining the preset damping coefficient and the initial loop current, the parasitic resistance of the initial coil is optimized iteratively to obtain the parasitic resistance of the target coil; Wherein, the initial coil parasitic resistance is the DC resistance of the coil of the wireless power transmission system; The preset formula for calculating the equivalent load resistance is used to characterize the mapping relationship between the equivalent load resistance of the wireless power transmission system and the output power and coil parasitic resistance. The preset damping coefficient is used to update the parasitic resistance of the coil during the iteration process.

[0104] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0105] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for calculating the parasitic resistance of a coil in a wireless power transmission system, characterized in that, The method includes: Obtain the preset output power and initial coil parasitic resistance of the wireless power transmission system; The initial load equivalent resistance is determined based on the preset output power, initial coil parasitic resistance, and preset load equivalent resistance calculation formula of the wireless power transmission system, and the initial loop current is determined based on the initial load equivalent resistance. Based on the iterative algorithm combining the preset damping coefficient and the initial loop current, the parasitic resistance of the initial coil is optimized iteratively to obtain the parasitic resistance of the target coil; Wherein, the initial coil parasitic resistance is the DC resistance of the coil of the wireless power transmission system; The preset formula for calculating the equivalent load resistance is used to characterize the mapping relationship between the equivalent load resistance of the wireless power transmission system and the output power and coil parasitic resistance. The preset damping coefficient is used to update the parasitic resistance of the coil during the iteration process.

2. The method for calculating the parasitic resistance of a coil in a wireless power transmission system according to claim 1, characterized in that, The step of optimizing the initial coil parasitic resistance using an iterative algorithm combining a preset damping coefficient and the initial loop current to obtain the target coil parasitic resistance includes: Repeat the iterative steps until the preset convergence condition is met, and use the parasitic resistance obtained in the last iteration as the parasitic resistance of the target coil. The iterative steps include: The loop current from the previous iteration is input into the preset magnetic field calculation model to obtain the magnetic field distribution for the current iteration; Based on the magnetic field distribution of this iteration and the loop current of the previous iteration, determine the candidate parasitic resistance for this iteration; The parasitic resistance of this iteration is obtained based on the parasitic resistance of the previous iteration, the preset damping coefficient, and the candidate parasitic resistance of this iteration. Based on the preset output power, the parasitic resistance of this iteration, and the preset load equivalent resistance calculation formula, the load equivalent resistance of this iteration is determined, and the loop current of this iteration is determined based on the load equivalent resistance of this iteration. The preset convergence condition is that the error between the loop current of the current iteration and the loop current of the previous iteration is less than a preset error value. The loop current from the previous iteration used in the first iteration is the initial loop current; The parasitic resistance of the previous iteration used in the first iteration is the parasitic resistance of the initial coil.

3. The method for calculating the parasitic resistance of a coil in a wireless power transmission system according to claim 2, characterized in that, The step of obtaining the parasitic resistance of the current iteration based on the parasitic resistance of the previous iteration, the preset damping coefficient, and the candidate parasitic resistance of the current iteration includes: Obtain the difference between the candidate parasitic resistance in the current iteration and the parasitic resistance in the previous iteration; Based on the difference value and the preset damping coefficient, the parasitic resistance of the previous iteration is updated, and the parasitic resistance of the current iteration is obtained based on the updated parasitic resistance of the previous iteration.

4. The method for calculating the parasitic resistance of a wireless power transmission system coil according to claim 2, characterized in that, The preset error value is less than the product of the preset damping coefficient and the preset coefficient.

5. The method for calculating the parasitic resistance of a coil in a wireless power transmission system according to claim 1, characterized in that, The step of determining the initial load equivalent resistance based on the preset output power of the wireless power transmission system, the initial coil parasitic resistance, and the preset load equivalent resistance calculation formula includes: To obtain the input voltage, operating frequency, and mutual inductance value of the wireless power transmission system; The initial load equivalent resistance is determined based on the preset output power, initial coil parasitic resistance, input voltage, operating frequency, mutual inductance value, and the preset load equivalent resistance calculation formula.

6. The method for calculating the parasitic resistance of a coil in a wireless power transmission system according to any one of claims 1 to 5, characterized in that, The wireless power transmission system includes at least one of a transmitting coil and a receiving coil.

7. The method for calculating the parasitic resistance of a coil in a wireless power transmission system according to claim 1, characterized in that, The preset formula for calculating the equivalent resistance of the load is as follows: ； in, Indicates the equivalent resistance of the load; Indicates the preset output power; This represents the parasitic resistance of the transmitting coil; This represents the parasitic resistance of the receiving coil; Indicates the input voltage; Indicates the operating frequency; This represents the mutual inductance between the transmitting coil and the receiving coil.

8. A device for calculating the parasitic resistance of a coil in a wireless power transmission system, characterized in that, The device includes: The acquisition module is used to acquire the preset output power and initial coil parasitic resistance of the wireless power transmission system; The determination module is used to determine the initial load equivalent resistance based on the preset output power of the wireless power transmission system, the initial coil parasitic resistance, and the preset load equivalent resistance calculation formula, and to determine the initial loop current based on the initial load equivalent resistance. The optimization module is used to perform iterative optimization on the initial coil parasitic resistance based on an iterative algorithm that combines a preset damping coefficient and the initial loop current, so as to obtain the target coil parasitic resistance. Wherein, the initial coil parasitic resistance is the DC resistance of the coil of the wireless power transmission system; The preset formula for calculating the equivalent load resistance is used to characterize the mapping relationship between the equivalent load resistance of the wireless power transmission system and the output power and coil parasitic resistance. The preset damping coefficient is used to update the parasitic resistance of the coil during the iteration process.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the method for calculating the parasitic resistance of a coil in a wireless power transmission system as described in any one of claims 1 to 7.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the method for calculating the parasitic resistance of the coil in a wireless power transmission system as described in any one of claims 1 to 7.

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