Parameter design method and system for LCC-S type wireless power transmission system

Abstract

The invention discloses a parameter design method and system for an LCC-S type wireless power transmission system. The method comprises the steps that inverter output current, primary side coil current and secondary side coil current are solved; dividing the dead time into discrete values according to the minimum clock unit of the controller, calculating ZVS regions based on the output current of the inverter, the maximum load resistance and the minimum load resistance, and obtaining an intersection of the obtained ZVS regions to obtain a ZVS parameter domain; calculating a parameter domain meeting the output power constraint; calculating a parameter domain meeting the overall efficiency constraint; taking an intersection of the ZVS parameter domain, the parameter domain meeting the output power constraint and the parameter domain meeting the complete machine efficiency constraint to obtain a target parameter domain; parameters in the target parameter domain are taken to compare power efficiency products in the whole load range, and the parameter with the minimum total loss is the optimal parameter.

Description

Technical Field

[0001] The present invention relates to the field of parameter design, and particularly to a parameter design method and system for an LCC-S type wireless power transmission system. Background Art

[0002] The application market scale of portable consumer electronic products such as mobile phones and wearable devices is gradually expanding, and their demand for wireless power transmission systems is also increasing day by day. The LCC-S type topology adds an impedance network compared with the S-S type topology, and has advantages such as high safety and constant voltage output characteristics, and has received wide attention. The parameters of the inductance and capacitance in the impedance network will affect the soft switching characteristics, output power and overall efficiency of the power devices in the system. In a 6.78 MHz wireless power transmission system, gallium nitride power devices with better switching characteristics and small parasitic parameters are generally selected. Their switching losses and reverse conduction losses will reduce the system efficiency, are not conducive to heat dissipation, and limit the power density of the system. In addition, the wireless power transmission system needs to meet the output power requirements of the load. Moreover, the parameter values of the impedance network determine the upper limit value of the system efficiency. The previous parameter design methods often only target a single goal, such as constant output characteristics, soft switching characteristics, efficiency, etc., and do not take into account multiple requirements. And the parasitic internal resistance of the resonant elements is not considered, and the accuracy of the model needs to be improved. There is a lack of an impedance network design method for the bridge topology that can simultaneously meet multiple design goals such as soft switching characteristics, rated output power and figure of merit. Summary of the Invention

[0003] The purpose of the present invention is to provide a parameter design method and system for an LCC-S type wireless power transmission system to overcome the problems existing in the prior art. Through time-domain and frequency-domain analysis, the present invention calculates the impedance network parameters that simultaneously meet multiple goals, ensures that the system is in the critical zero voltage switching (ZVS) working condition under a wide load range, and has a constant output voltage and the lowest loss.

[0004] To achieve the above object, the present invention adopts the following technical solutions: A parameter design method for an LCC-S type wireless power transmission system includes the following steps: Step 1: According to the frequency-domain equivalent circuit diagram, write the Kirchhoff equations, substitute the DC input voltage and load range under the target working condition into the Kirchhoff equations, and solve for the inverter output current, primary coil current and secondary coil current; Step 2: Divide the dead time into discrete values according to the minimum clock unit of the controller, calculate the ZVS region based on the inverter output current and the maximum load resistance and minimum load resistance, and take the intersection of the obtained ZVS regions to obtain the ZVS parameter domain; Step 3: Take the load resistance under the rated condition, calculate the output power surface of the ZVS parameter domain, and take the area where the output power is greater than the expected value of the output power as the parameter domain that meets the output power constraint; Step 4: Take the load resistance under the rated condition and the light load condition, calculate the overall efficiency surface of the ZVS parameter domain, and take the area where the overall efficiency is higher than the expected value of the overall efficiency as the parameter domain that meets the overall efficiency constraint; Step 5: Take the intersection of the ZVS parameter domain, the parameter domain that meets the output power constraint, and the parameter domain that meets the overall efficiency constraint to obtain the target parameter domain that simultaneously meets the ZVS condition, output power constraint, and overall efficiency constraint; Step 6: Compare the power efficiency products of the parameters in the target parameter domain over the entire load range, and the parameter with the minimum total loss is the optimal parameter.

[0005] Furthermore, in Step 1, the output current of the inverter, the primary coil current, and the secondary coil current are solved, and the specific formulas are as follows:

[0006]

[0007] Among them, and are detuning factors, defined as , , , , are the auxiliary inductor, the self-inductance of the primary coil, and the self-inductance of the secondary coil respectively, is the series resonant capacitor, and ; , and are the corresponding series equivalent resistances respectively; is the equivalent input impedance of the rectifier, and , is the load resistance; and are the fundamental wave and th harmonic component of the output voltage of the inverter respectively; , , are the output current of the inverter, the primary coil current, and the secondary coil current respectively, and the subscript corresponds to its harmonic order; is the coupling coefficient between coils; is the operating angular frequency.

[0008] Further, in the second step, the dead time is divided into discrete values according to the minimum clock unit of the controller, and the ZVS region is calculated based on the inverter output current and the maximum and minimum load resistances, which is specifically expressed as:

[0009] Wherein, and are respectively and the amounts of charge provided to the converter within the dead time to achieve the ZVS operating condition; is half of the dead time.

[0010] Further, the load resistance under the rated condition is taken to calculate the output power surface of the ZVS parameter domain, specifically: Take the load resistance under the rated condition, calculate the output power of the parameters in the ZVS parameter domain under the rated condition, and then obtain the output power surface.

[0011] Further, the calculation of the output power of the parameters in the ZVS parameter domain under the rated condition, the specific formula is:

[0012] Wherein, is the output power, is the system DC input voltage.

[0013] Further, the load resistances under the rated condition and the light load condition are taken to calculate the overall efficiency surface of the ZVS parameter domain, specifically: Take the rated load resistance to calculate the overall efficiency of the parameters in the ZVS parameter domain under the rated condition, and obtain the overall efficiency surface of the ZVS parameter domain under the rated condition; Take the maximum load resistance to calculate the overall efficiency of the parameters in the ZVS parameter domain under the light load condition, and obtain the overall efficiency surface of the ZVS parameter domain under the light load condition; Take the intersection of the overall efficiency surface of the ZVS parameter domain under the rated condition and the overall efficiency surface of the ZVS parameter domain under the light load condition to obtain the overall efficiency surface of the ZVS parameter domain.

[0014] Further, the overall efficiency calculation formula is as follows:

[0015] Wherein, is the overall efficiency; is the on-resistance of the power device; is the reverse breakdown voltage of the diode; is the reverse recovery charge of the diode; is the switching frequency; is the on-resistance of the diode; , , are the losses of the inverter, resonant network, and rectifier, respectively.

[0016] A parameter design system for an LCC-S type wireless power transfer system, comprising: A current solving module: configured to write Kirchhoff's equations according to the frequency-domain equivalent circuit diagram, substitute the DC input voltage and load range under the target operating conditions into Kirchhoff's equations, and solve for the inverter output current, primary coil current, and secondary coil current; A first parameter domain obtaining module: configured to divide the dead time into discrete values according to the minimum clock unit of the controller, calculate the ZVS region based on the inverter output current and the maximum and minimum load resistances, and take the intersection of the obtained ZVS regions to obtain the ZVS parameter domain; A second parameter domain obtaining module: configured to take the load resistance under the rated operating conditions, calculate the output power surface of the ZVS parameter domain, and take the region where the output power is greater than the expected output power as the parameter domain satisfying the output power constraint; A third parameter domain obtaining module: configured to take the load resistances under the rated operating conditions and light load conditions, calculate the overall efficiency surface of the ZVS parameter domain, and take the region where the overall efficiency is higher than the expected overall efficiency as the parameter domain satisfying the overall efficiency constraint; A target parameter domain obtaining module: configured to take the intersection of the ZVS parameter domain, the parameter domain satisfying the output power constraint, and the parameter domain satisfying the overall efficiency constraint to obtain the target parameter domain that simultaneously satisfies the ZVS operating conditions, output power constraint, and overall efficiency constraint; An optimal parameter obtaining module: configured to compare the parameter pairs in the target parameter domain for the power efficiency product over the entire load range, and the parameter with the minimum total loss is the optimal parameter.

[0017] A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of the parameter design method for the LCC-S type wireless power transfer system are implemented.

[0018] A computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the steps of the parameter design method for the LCC-S type wireless power transfer system are implemented.

[0019] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention can design the optimal resonant network parameters for the LCC-S type wireless power transfer system at 6.78 MHz, enabling the LCC-S type wireless power transfer system to achieve critical ZVS within the target operating conditions, reducing the switching loss and reverse conduction loss; meeting the rated output power constraint (i.e., the expected value of the output power) and the overall efficiency constraint (i.e., the expected value of the overall efficiency); having the lowest loss within the entire load range, reducing the heat dissipation of the LCC-S type wireless power transfer system. At the same time, the present invention avoids the programming link of the intelligent algorithm, saving the calculation time and hardware cost. Description of the Drawings

[0020] The accompanying drawings in the specification are used to provide a further understanding of the present invention and form a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0021] Figure 1 It is the logic flowchart of the parameter design method of the present invention.

[0022] Figure 2 It is the system topology structure diagram based on the LCC-S type resonant network.

[0023] Figure 3 It is the frequency domain equivalent circuit diagram.

[0024] Figure 4 It is the ZVS parameter domain with Td = 2.5 ns to 15 ns and RL = 30 Ω to 160 Ω.

[0025] Figure 5 It is the output power surface diagram with Td = 7.5 ns and RL = 30 Ω.

[0026] Figure 6 It is the overall efficiency surface diagram with Td = 7.5 ns and RL = 30 Ω.

[0027] Figure 7 It is the target parameter domain under multiple constraint conditions. Detailed Embodiments

[0028] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0029] It should be noted that the terms "first", "second", etc. in the description, claims and above-mentioned drawings of the present invention are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0030] Embodiment 1 A parameter design method for an LCC-S type wireless power transmission system, characterized by comprising the following steps: Step 1: According to the frequency-domain equivalent circuit diagram, write the Kirchhoff equations, substitute the DC input voltage and load range under the target operating conditions into the Kirchhoff equations, and solve for the inverter output current, primary coil current, and secondary coil current. Step 2: Divide the dead time into discrete values according to the minimum clock unit of the controller, calculate the ZVS region based on the inverter output current and the maximum and minimum load resistances, and take the intersection of the obtained ZVS regions to obtain the ZVS parameter domain. Step 3: Take the load resistance under the rated operating conditions, calculate the output power surface of the ZVS parameter domain, and take the region where the output power is greater than the expected value of the output power as the parameter domain that satisfies the output power constraint. Step 4: Take the load resistances under the rated operating conditions and light load conditions, calculate the overall efficiency surface of the ZVS parameter domain, and take the region where the overall efficiency is higher than the expected value of the overall efficiency as the parameter domain that satisfies the overall efficiency constraint. Step 5: Take the intersection of the ZVS parameter domain, the parameter domain that satisfies the output power constraint, and the parameter domain that satisfies the overall efficiency constraint to obtain the target parameter domain that simultaneously satisfies the ZVS operating conditions, output power constraint, and overall efficiency constraint. Step 6: Compare the parameter pairs in the target parameter domain for the power efficiency product over the entire load range, and the parameter with the minimum total loss is the optimal parameter.

[0031] The present invention can design the optimal resonance network parameters for an LCC-S type wireless power transfer system at 6.78 MHz, enabling the LCC-S type wireless power transfer system to achieve critical ZVS within the target operating conditions, reducing switching losses and reverse conduction losses; meeting the rated output power constraint (i.e., the expected output power) and the overall machine efficiency constraint (i.e., the expected overall machine efficiency); having the lowest losses across the entire load range, reducing the heat dissipation of the LCC-S type wireless power transfer system. At the same time, the present invention avoids the programming link of intelligent algorithms, saving calculation time and hardware costs.

[0032] Embodiment 2 The present invention provides a parameter design method for an LCC-S type wireless power transfer system. The self-inductance of the coil is determined by the size, structure, etc. of the coil and depends on the space reserved in the actual operating conditions. Therefore, the self-inductance of the transmitting coil L p is first determined by the target operating conditions. The primary and secondary coils are kept the same, so the self-inductance of the secondary coil L s = L p . The secondary compensation capacitor C s resonates with the self-inductance of the secondary coil L s . The primary auxiliary inductor L f resonates with the auxiliary capacitor C f , so C s = 1 / ω 1 2 L s , C f = 1 / ω 1 2 L f . In the present invention, the detuning factor is defined as α = L f / L p and β = ω 1 2 ( L p - L f ) C p , ω 1 is the working angular frequency.

[0033] Specifically, it includes the following steps: First step: According to the equivalent circuit diagram in the frequency domain, write down the Kirchhoff equations. Substitute the DC input voltage and load range under the target working conditions into the equations to solve for the output current of the inverter i f , the primary coil current i p , and the secondary coil current i s .

[0034] Second step: Calculate the integral of the current during the dead time to obtain the charge that the resonant network can provide during the dead time Q zvs . Then compare the calculated Q zvs with the charge required for the power device to achieve the zero voltage switching (ZVS) working condition Q oss . When Q zvs < Q oss , the power device is in the partial ZVS working condition; when Q zvs = Q oss , the power device is in the critical ZVS working condition; when Q zvs > Q oss , the power device is in the over-ZVS working condition. Since Q zvs = Q oss this equation is a transcendental equation and it is difficult to obtain an analytical solution. In addition, the clock frequency of the controller is no longer much greater than the system working frequency, making it difficult to achieve high-precision control of the dead time. Therefore, numerical calculations are performed based on the clock resolution of the controller, and different dead times are substituted to calculate Q zvs . Since the reverse conduction loss of GaN devices is relatively large at high frequencies, the dead time should be taken as the minimum value required to achieve the ZVS working condition. The discrete values of the dead time are selected according to the minimum clock period of the controller and substituted into Q zvs = Q oss to solve for the ZVS parameter domain. Due to the influence of parasitic parameters, the change in the load resistance will affect the ZVS working condition of the inverter. As the load resistance increases, Q zvs gradually decreases. Therefore, the maximum load resistance and the minimum load resistance are respectively substituted for calculation, and the intersection of the two parameter domains is taken to obtain the ZVS parameter domain for achieving the ZVS working condition at different dead times under the full load range

[0035] In the third step, to ensure that the system has sufficient output power under rated conditions, the load resistance under rated conditions is used to calculate the output power surface of the ZVS parameter domain. The region where the output power is greater than the expected value of the output power is the parameter domain that satisfies the output power constraint.

[0036] In the fourth step, to ensure that the system has a high overall efficiency within the load range, the load resistances under rated conditions and light load conditions are used to calculate the overall efficiency surface of the ZVS parameter domain. The region with an overall efficiency higher than the expected value of the overall efficiency is the parameter domain that satisfies the overall efficiency constraint.

[0037] In the fifth step, the intersection of the parameter domains obtained in the second, third, and fourth steps is taken to obtain the parameter domain that simultaneously satisfies the ZVS condition, output power constraint, and overall efficiency constraint. The parameter pairs in the target parameter domain are compared for the power efficiency product over the entire load range, and the parameter with the minimum total loss is the optimal parameter.

[0038] Embodiment 3 As Figure 1 shown, a parameter design method for an LCC-S type wireless power transfer system provided by the present invention is based on the wireless power transfer system as Figure 2 shown, and the method includes the following steps: Step 1: Calculate the inverter output current, primary coil current, and secondary coil current according to the coil self-inductance, input voltage, and load range; Step 2: Divide the dead time into discrete values according to the minimum clock unit of the controller, and substitute them to calculate the ZVS parameter domain of the system. In this embodiment, the minimum clock unit of the controller is 2.5 ns. The maximum load resistance and the maximum load resistance are respectively selected, and take T d = 2.5 ns to 15 ns, calculate the ZVS parameter domains with different dead times under the two working conditions and take the intersection to obtain the ZVS parameter domain that can achieve ZVS over the entire load range; Step 3: Use the load resistance under rated conditions to calculate the output power surface of the ZVS parameter domain to obtain the parameter domain that satisfies the output power constraint; Step 4: Use the load resistance under rated conditions to calculate the overall efficiency surface of the ZVS parameter domain, and then calculate the overall efficiency surface under light load conditions to obtain the parameter domain that satisfies the efficiency constraint; Step 5: For the target parameter domain obtained by taking the intersection of the above parameter domains, calculate the power efficiency product of the parameters in the target parameter domain over the entire load range, and take the parameter with the minimum loss among them as the optimal parameter.

[0039] Specifically, the topological structure of the wireless power transfer system based on the LCC-S type resonant network is asFigure 2 As shown, it includes a DC power supply V 1, a high-frequency inverter, a primary resonant network, a secondary controller, a secondary resonant network, a full-bridge rectifier, and a load equivalent resistance R L . The primary resonant network includes an auxiliary inductor L f , a parallel resonant capacitor C f , a primary coil L p , and a series resonant capacitor C p . The secondary resonant network includes a secondary coil L s , and a secondary resonant capacitor C s . Among them i f , i p and i s are the inverter output current, the primary coil current, and the secondary coil current respectively. a and b are the midpoints of the first bridge arm and the second bridge arm of the inverter respectively

[0040] According to Figure 3 the frequency-domain equivalent circuit diagram shown, the respective frequency components of the current can be calculated, and the Q zvs that can be provided by the resonant network for soft switching within the dead time can be calculated

[0041] (1) (2) (3) Among them and are detuning factors, defined as , , , , are the auxiliary inductor, the self-inductance of the primary coil, and the self-inductance of the secondary coil respectively is the series resonant capacitor, and ; , and are the corresponding series equivalent resistances respectively is the rectifier equivalent input impedance, and , is the load resistance and are the fundamental wave of the inverter output voltage and Subharmonic component; , , are the inverter output current, the primary coil current, and the secondary coil current respectively, and the subscript corresponds to its harmonic order; is the coupling coefficient between coils; is the working angular frequency; and are respectively and the charge provided to the converter within the dead time to achieve the ZVS condition; is half of the dead time At a working frequency of 6.78 MHz, the parasitic internal resistance of the auxiliary inductor L f cannot be ignored, and the change in the equivalent input impedance Z eq of the rectifier will affect the amplitude and phase of the inverter output current i f . Therefore, within the load range of the target condition, the maximum load resistance and the minimum load resistance are respectively taken to calculate their ZVS regions. To ensure that the system is always in the critical ZVS condition during the load change process, the intersection of the obtained ZVS regions is taken to obtain the ZVS parameter domain as shown in Figure 4 .

[0042] Take the load resistance under the rated condition and calculate the output power of the parameters within the ZVS parameter domain under the rated condition to obtain the output power surface as shown in Figure 5 . Take the output power constraint (i.e., the expected value of the output power) as 50 W, then the intersection line of the output power surface and the 50 W plane can be obtained, that is, the red dashed line in the figure. The parameters with an output power higher than 50 W satisfy the output power constraint, that is, the parameter domain that satisfies the output power constraint is obtained.

[0043] (4) Among them, is the output power, is the DC input voltage of the system.

[0044] The overall efficiency constraint is the efficiency under the rated condition and the efficiency under the light load condition. Therefore, take the minimum load resistance to calculate the overall efficiency of the parameters within the ZVS parameter domain under the rated condition to obtain the overall efficiency surface as shown in Figure 6 . Similarly, then take the maximum load resistance to calculate the overall efficiency of the parameters within the ZVS region under the light load condition to obtain the corresponding overall efficiency surface. Take the intersection of the two overall efficiency surfaces to obtain the overall efficiency surface of the ZVS parameter domain. In this embodiment, the overall efficiency constraint under the rated condition is 88%, and the overall efficiency constraint under the light load condition is 75%.

[0045] (5) wherein is the overall efficiency; is the on-resistance of the power device; is the reverse breakdown voltage of the diode; is the reverse recovery charge of the diode; is the switching frequency; is the on-resistance of the diode; , , are the losses of the inverter, resonant network and rectifier, respectively.

[0046] Taking the intersection of the above parameter regions can obtain the target parameter domain that satisfies the ZVS condition, output power constraint, and overall efficiency constraint, as shown in Figure 7 . To obtain the optimal figure of merit within the entire load range and minimize the heat generated by the load during charging, the parameters in the target parameter domain are compared for the figure of merit within the entire load. The parameter with the minimum total loss is the optimal parameter. In this embodiment, although the parameters at point X and the parameters at point Y are both within the target parameters, the loss of the parameters at point X within the load range is higher than that of the parameters at point Y. Therefore, the parameters at point Y are finally the optimal parameters.

[0047] Therefore, the present invention adopts a parameter design method with multiple condition constraints, using the detuning factor as a variable. First, the parameter domain that satisfies the ZVS condition within the load range is calculated, and then its output power and overall efficiency are calculated to obtain the target parameter domain that satisfies the ZVS condition, output power constraint, and overall efficiency constraint. The parameters within the target parameter domain are selected to calculate the cumulative figure of merit within the entire load range, and the parameter with the highest figure of merit is selected as the optimal parameter. The present invention simplifies the parameter design process of the system at 6.78 MHz, reducing the calculation cost and complexity.

[0048] Embodiment 4 The present invention provides a parameter design system for an LCC-S type wireless power transmission system, including: A current solving module: used to write Kirchhoff equations according to the frequency-domain equivalent circuit diagram, substitute the DC input voltage and load range under the target working conditions into the Kirchhoff equations, and solve for the inverter output current, primary coil current, and secondary coil current; A first parameter domain obtaining module: used to divide the dead time into discrete values according to the minimum clock unit of the controller, calculate the ZVS region based on the inverter output current and the maximum load resistance and minimum load resistance, and take the intersection of the obtained ZVS regions to obtain the ZVS parameter domain; A second parameter domain obtaining module: used to take the load resistance under the rated working condition, calculate the output power surface of the ZVS parameter domain, and take the region where the output power is greater than the expected output power as the parameter domain that satisfies the output power constraint; The third parameter domain acquisition module: used to obtain the load resistance under rated conditions and light load conditions, calculate the overall machine efficiency surface of the ZVS parameter domain, and take the area where the overall machine efficiency is higher than the expected value of the overall machine efficiency as the parameter domain that meets the overall machine efficiency constraint; The target parameter domain acquisition module: used to take the intersection of the ZVS parameter domain, the parameter domain that meets the output power constraint, and the parameter domain that meets the overall machine efficiency constraint to obtain the target parameter domain that simultaneously meets the ZVS operating condition, output power constraint, and overall machine efficiency constraint; The optimal parameter acquisition module: used to compare the parameter pairs in the target parameter domain for the power efficiency product over the entire load range, and the parameter with the minimum total loss is the optimal parameter.

[0049] Embodiment Five This embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the parameter design method of the LCC-S type wireless power transmission system are implemented.

[0050] Embodiment Six This embodiment provides a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the parameter design method of the LCC-S type wireless power transmission system are implemented.

[0051] Those skilled in the art should understand that the embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0052] The present invention is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, as well as the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0053] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to operate in a particular manner, such that the instructions stored in the computer-readable memory produce a manufacture including instruction means that implement the functions specified in one or more of the processes and / or blocks Figure 1 of one or more of the processes and / or blocks Figure 1 of one or more of the blocks

[0054] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, whereby the instructions executed on the computer or other programmable apparatus provide steps for implementing the functions specified in one or more of the processes and / or blocks Figure 1 of one or more of the processes and / or blocks Figure 1 of one or more of the blocks

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the scope of its protection. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: after reading the present invention, those skilled in the art may still make various changes, modifications or equivalent replacements to the specific embodiments of the invention, but these changes, modifications or equivalent replacements are all within the scope of protection of the pending claims of the invention.

Claims

1. A parameter design method for an LCC-S type wireless power transfer system, characterized in that It includes the following steps: Step 1: According to the frequency-domain equivalent circuit diagram, write the Kirchhoff equations, substitute the DC input voltage and load range under the target operating conditions into the Kirchhoff equations, and solve for the inverter output current, primary coil current, and secondary coil current; Step 2: Divide the dead time into discrete values according to the minimum clock unit of the controller, calculate the ZVS region based on the inverter output current, maximum load resistance, and minimum load resistance, and take the intersection of the obtained ZVS regions to obtain the ZVS parameter domain; Step 3: Take the load resistance under the rated operating conditions, calculate the output power surface of the ZVS parameter domain, and take the region where the output power is greater than the expected output power value as the parameter domain that meets the output power constraint; Step 4: Take the load resistance under the rated operating conditions and light load conditions, calculate the overall efficiency surface of the ZVS parameter domain, and take the region where the overall efficiency is higher than the expected overall efficiency value as the parameter domain that meets the overall efficiency constraint; Step 5: Take the intersection of the ZVS parameter domain, the parameter domain that meets the output power constraint, and the parameter domain that meets the overall efficiency constraint to obtain the target parameter domain that simultaneously meets the ZVS operating conditions, output power constraint, and overall efficiency constraint; Step 6: Take the parameters in the target parameter domain and compare the power efficiency products over the entire load range. The parameter with the minimum total loss is the optimal parameter.

2. The parameter design method of an LCC-S type wireless power transfer system according to claim 1, wherein In step 1, the inverter output current, primary coil current, and secondary coil current are solved, and the specific formulas are: Among them, and are detuning factors, defined as , , , , are the auxiliary inductance, the primary coil self-inductance, and the secondary coil self-inductance respectively, is the series resonance capacitor, and ; , and are the corresponding series equivalent resistances respectively; is the rectifier equivalent input impedance, and , is the load resistance; and are the fundamental wave and th harmonic component of the inverter output voltage respectively; , , are the inverter output current, the primary coil current, and the secondary coil current respectively, and the subscript corresponds to its harmonic order; is the coupling coefficient between coils; is the working angular frequency.

3. The parameter design method of an LCC-S type wireless power transfer system according to claim 2, characterized in that In step 2, the dead time is divided into discrete values according to the minimum clock unit of the controller, and the ZVS region is calculated based on the inverter output current, maximum load resistance, and minimum load resistance, which is specifically expressed as: wherein, and are respectively and the amounts of electric charge provided to the converter during the dead time to achieve the ZVS condition; is half of the dead time.

4. The parameter design method of an LCC-S type wireless power transmission system according to claim 2, characterized in that, Taking the load resistance under the rated operating conditions and calculating the output power surface of the ZVS parameter domain is specifically: Taking the load resistance under the rated operating conditions, calculating the output power of the parameters in the ZVS parameter domain under the rated operating conditions, and thus obtaining the output power surface.

5. The parameter design method of an LCC-S type wireless power transmission system according to claim 4, characterized in that, The specific formula for calculating the output power of the parameters in the ZVS parameter domain under the rated operating conditions is: Among them, is the output power, is the DC input voltage of the system.

6. The parameter design method of an LCC-S type wireless power transmission system according to claim 5, characterized in that, Taking the load resistance under the rated operating conditions and light load conditions and calculating the overall efficiency surface of the ZVS parameter domain is specifically: Taking the rated load resistance and calculating the overall efficiency of the parameters in the ZVS parameter domain under the rated operating conditions to obtain the overall efficiency surface of the ZVS parameter domain under the rated operating conditions; Taking the maximum load resistance and calculating the overall efficiency of the parameters in the ZVS parameter domain under the light load conditions to obtain the overall efficiency surface of the ZVS parameter domain under the light load conditions; Taking the intersection of the overall efficiency surface of the ZVS parameter domain under the rated operating conditions and the overall efficiency surface of the ZVS parameter domain under the light load conditions to obtain the overall efficiency surface of the ZVS parameter domain.

7. A parameter design method for an LCC-S type wireless power transmission system according to claim 6, characterized in that, The overall efficiency calculation formula is as follows: Among them, is the overall efficiency; is the on-resistance of the power device; is the reverse breakdown voltage of the diode; is the reverse recovery charge of the diode; is the switching frequency; is the on-resistance of the diode; , , are the losses of the inverter, resonant network, and rectifier, respectively.

8. A parameter design system for an LCC-S type wireless power transmission system, characterized in that, It includes: Current Solving Module: Used to write the Kirchhoff equations according to the frequency-domain equivalent circuit diagram, substitute the DC input voltage and load range under the target operating conditions into the Kirchhoff equations, and solve for the inverter output current, primary coil current, and secondary coil current; The first parameter domain acquisition module: It is used to divide the dead time into discrete values according to the minimum clock unit of the controller, calculate the ZVS region based on the inverter output current and the maximum and minimum load resistances, and take the intersection of the obtained ZVS regions to obtain the ZVS parameter domain; The second parameter domain acquisition module: It is used to take the load resistance under the rated working condition, calculate the output power surface of the ZVS parameter domain, and take the region where the output power is greater than the expected output power value as the parameter domain that meets the output power constraint; The third parameter domain acquisition module: It is used to take the load resistances under the rated working condition and the light load working condition, calculate the overall machine efficiency surface of the ZVS parameter domain, and take the region where the overall machine efficiency is higher than the expected overall machine efficiency value as the parameter domain that meets the overall machine efficiency constraint; The target parameter domain acquisition module: It is used to take the intersection of the ZVS parameter domain, the parameter domain that meets the output power constraint, and the parameter domain that meets the overall machine efficiency constraint to obtain the target parameter domain that simultaneously meets the ZVS working condition, output power constraint, and overall machine efficiency constraint; The optimal parameter acquisition module: It is used to take the parameters in the target parameter domain and compare the power efficiency products within the entire load range, and the parameter with the minimum total loss is the optimal parameter.

9. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the parameter design method of an LCC-S type wireless power transmission system according to any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the parameter design method of an LCC-S type wireless power transmission system according to any one of claims 1 to 7.

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