Receiving end lightweight method based on autonomous resonance WPT system

Abstract

The invention relates to a receiving end lightweight method based on an autonomous resonance WPT system. The method comprises the following steps: constructing a strong asymmetric relationship between self-inductance of a transmitting coil and self-inductance of a receiving coil in a resonance network; constructing a first relation model and an equivalent impedance calculation model, wherein the first relation model is a relation model between the equivalent impedance of the receiving end at the transmitting end and the resonant capacitance of the receiving end and the self-inductance of the receiving coil; based on the equivalent impedance calculation model, obtaining the equivalent impedance under preset output power; and calculating asymmetric resonance parameters according to the strong asymmetric relationship, the first relationship model and the equivalent impedance. On the premise of ensuring the electric energy transmission power, the anti-offset capability and the transmission efficiency of the mobile phone wireless charging system are improved, and the heating of the mobile phone is reduced.

Description

Technical Field

[0001] The present invention relates to the field of wireless charging technology, and in particular to a receiving end lightweight method based on an autonomous resonance WPT system. Background Art

[0002] In recent years, wireless charging has been increasingly used due to its safety and convenience. Mobile phones are the devices with the largest wireless charging application market and the fastest product updates. In order to prevent high-frequency and high-power electromagnetic fields from causing harm to the human body and other electronic devices, a series of standards such as Qi, PMA, and A4WP have been formulated to regulate the frequency band and power of portable wireless charging systems. However, this has also greatly narrowed the parameter selection range of traditional wireless charging technology, causing it to have to make a certain compromise between efficiency and power. The inductance values ​​of the existing commercial mobile phone wireless charging transmitting coil and receiving coil are the same or not much different, which leads to a large self-inductance of the receiving coil, which means a large resistance, which consumes energy and reduces efficiency, and is the main cause of mobile phone heating. The frequency range specified by the commercial standard is 100kHz to 150kHz. The commercial SS circuit topology solution can only obtain the required output power near the resonant frequency point, wasting the frequency band utilization. The overall efficiency of the commercial SS circuit topology solution will fluctuate significantly with the change of coupling strength. As the coupling strength decreases, the transmission efficiency will decrease significantly, that is, the anti-offset capability is poor, and it is accompanied by severe heating at the mobile phone end.

[0003] Therefore, how to improve the efficiency and anti-drift capability of the mobile phone wireless charging system and reduce the heating of the mobile phone under the premise of ensuring power output is an urgent problem to be solved. In view of the above-mentioned defects of the prior art, the present invention proposes a lightweight receiving end method based on the autonomous resonance WPT system, which aims to improve the anti-drift capability and transmission efficiency of the mobile phone wireless charging system and reduce the heating of the mobile phone under the premise of ensuring the power transmission power. Summary of the invention

[0004] The purpose of the present invention is to provide a lightweight receiving end method based on an autonomous resonant WPT system, which can improve the anti-drift capability and transmission efficiency of a mobile phone wireless charging system and reduce the heating of the mobile phone while ensuring the power transmission power.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The lightweight receiving end method based on the autonomous resonance WPT system includes:

[0007] The strong asymmetric relationship between the self-inductance of the transmitting coil and the self-inductance of the receiving coil in the construction resonant network;

[0008] Constructing a first relationship model and an equivalent impedance calculation model, wherein the first relationship model is a relationship model between the equivalent impedance of the receiving end at the transmitting end and the resonant capacitance of the receiving end and the self-inductance of the receiving coil;

[0009] Based on the equivalent impedance calculation model, obtaining the equivalent impedance at a preset output power;

[0010] An asymmetric resonance parameter is calculated according to the strong asymmetric relationship, the first relationship model and the equivalent impedance.

[0011] Optionally, the asymmetric resonance parameters include the multiple a, the self-inductance L of the transmitting coil 1 , receiving coil self-inductance L r , receiving end resonant capacitor C r and the transmitter resonance parameter C 1 .

[0012] Optionally, the strong asymmetric relationship is:

[0013] L 1 =a·L r , a>10

[0014] Among them, L 1 is the self-inductance of the transmitting coil, a is the multiple, L r is the self-inductance of the receiving coil.

[0015] Optionally, the first relationship model is:

[0016]

[0017] Among them, R eq is the equivalent resistance of the receiving end at the transmitting end, ω is the angular frequency, M is the mutual inductance, X r With R r Represents the total impedance Z at the receiving end r The imaginary and real values ​​of the , k is the coupling coefficient, L r is the receiving coil self-inductance, C r is the resonant capacitance at the receiving end, and a is the multiple.

[0018] Optionally, the equivalent impedance calculation model is:

[0019]

[0020] Among them, R eq is the equivalent resistance of the receiving end at the transmitting end, R s is the parasitic resistance of the transmitting coil, R L is the equivalent load on the left side of the rectifier, R R is the parasitic resistance of the receiving coil, v fa is the inverter square wave voltage v1 The fundamental component of .

[0021] Optionally, the multiple a and the receiving end resonant capacitance C are calculated r The method comprises: obtaining a rated coupling coefficient range and a preset operating frequency range, and combining the first relationship model and the equivalent impedance to obtain a receiving end resonant capacitor C r and calculate the design range of the multiple a.

[0022] Optionally, calculating the multiple a includes:

[0023] Obtaining a minimum value of the rated coupling coefficient range and the preset operating frequency range;

[0024] When the rated coupling coefficient is at the minimum value and the preset operating frequency is at the minimum value, the imaginary part of the total input impedance is zero, and the compensation capacitor, i.e., the transmitter resonance parameter C, is calculated. 1 .

[0025] Optionally, the compensation capacitance can be calculated as:

[0026] X 1 +X eq ≥0|k=0.4,f=100kHz

[0027]

[0028] Among them, X 1 Represents the transmitter's own impedance Z 1 The imaginary part of X eq is the equivalent reactance of the receiving end at the transmitting end, k is the rated coupling strength, f is the operating frequency, C 1 is the transmitter resonance parameter, L 1 is the self-inductance of the transmitting coil, and ω is the angular frequency.

[0029] The beneficial effects of the present invention are:

[0030] The present invention can output 40W of power in the coupling strength range of 0.4-0.7 and the frequency range of 100kHz to 150kHz, and the efficiency is stable at about 90%. The system's anti-drift capability and frequency band utilization are greatly improved. The present invention can obtain 40W output power using only a 5μH receiving coil. Compared with the commercial 10μH receiving coil, the parasitic resistance is significantly reduced, and the temperature drops by 40°C during normal operation. The heating problem of mobile phones is well solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0032] Figure 1 This is a topology diagram of an autonomous resonance WPT system according to an embodiment of the present invention;

[0033] Figure 2 a, C in the embodiment of the present invention r and R eq The relationship surface of

[0034] Figure 3 The power efficiency comparison diagram of the traditional SS topology and the topology designed by the method according to the embodiment of the present invention is shown in FIG. 1 , wherein (a) is an output power comparison diagram of the traditional SS topology and the topology designed by the method, and (b) is a system efficiency comparison diagram of the traditional SS topology and the topology designed by the method;

[0035] Figure 4 The present invention is a flowchart of a lightweight receiving method based on an autonomous resonance WPT system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] like Figure 4 As shown, the present invention discloses a lightweight receiving end method based on an autonomous resonance WPT system, which is characterized by comprising:

[0039] The strong asymmetric relationship between the self-inductance of the transmitting coil and the self-inductance of the receiving coil in the construction resonant network;

[0040] Constructing a first relationship model and an equivalent impedance calculation model, wherein the first relationship model is a relationship model between the equivalent impedance of the receiving end at the transmitting end and the resonant capacitance of the receiving end and the self-inductance of the receiving coil;

[0041] Based on the equivalent impedance calculation model, the equivalent impedance under the preset output power is obtained;

[0042] Asymmetric resonance parameters are calculated based on the strong asymmetric relationship, the first relationship model and the equivalent impedance.

[0043] Furthermore, the asymmetric resonance parameters include the multiple a, the self-inductance L of the transmitting coil 1 , receiving coil self-inductance L r , receiving end resonant capacitor C r and the transmitter resonance parameter C 1 .

[0044] Furthermore, the strong asymmetric relationship is:

[0045] L 1 =a·L r , a>10

[0046] Among them, L 1 is the self-inductance of the transmitting coil, and a is a multiple, which represents how many times the inductance of the transmitting coil is that of the receiving coil, for example: the receiving coil L r If only 5μH is selected (a small value is selected to meet the requirements of lightweight or heat dissipation), the transmitting coil should be at least a*5μH to ensure system performance, L r is the self-inductance of the receiving coil.

[0047] Furthermore, the first relational model is:

[0048]

[0049] Among them, R eq is the equivalent resistance of the receiving end at the transmitting end, ω is the angular frequency, M is the mutual inductance, X r With R r Represents the total impedance Z at the receiving end r The imaginary and real values ​​of the , k is the coupling coefficient, L r is the receiving coil self-inductance, C r is the resonant capacitor at the receiving end, and a is the asymmetric resonance parameter.

[0050] Furthermore, the equivalent impedance calculation model is:

[0051]

[0052] Among them, R eq is the equivalent resistance of the receiving end at the transmitting end, R s is the parasitic resistance of the transmitting coil, R L is the equivalent load on the left side of the rectifier, R R is the parasitic resistance of the receiving coil, v fa is the inverter square wave voltage v 1 The fundamental component of .

[0053] Further, calculate the multiple a and the receiving end resonant capacitor C r Including: obtaining the rated coupling coefficient range and the preset operating frequency range, and combining the first relationship model and the equivalent impedance to obtain the receiving end resonant capacitor C r and calculate the design range of the multiple a.

[0054] Furthermore, the calculation of the multiple a includes:

[0055] Obtain the minimum value of the rated coupling coefficient range and the preset operating frequency range;

[0056] When the rated coupling coefficient is at the minimum value and the preset operating frequency is at the minimum value, the imaginary part of the total input impedance is made zero and the compensation capacitance is calculated.

[0057] Furthermore, the method for calculating the compensation capacitance is:

[0058] X 1 +X eq ≥0|k=0.4,f=100kHz

[0059]

[0060] Among them, X 1 Represents the transmitter's own impedance Z 1 The imaginary part of X eq is the equivalent reactance of the receiving end at the transmitting end, k is the rated coupling strength, f is the operating frequency, C 1 is the transmitter resonance parameter, L 1 is the self-inductance of the transmitting coil, ω is the angular frequency

[0061] Based on adaptive resonance WPT system Figure 1 As shown, it includes a DC-AC inverter unit, a transmitting end resonance unit, an energy negative feedback unit, a receiving end resonance unit, and an AC-DC conversion unit;

[0062] The DC-AC inverter unit consists of 4 MOSFET switches S 1 -S 4 A full-bridge inverter circuit is formed to convert the DC input voltage V i1 Invert to AC power;

[0063] The transmitting end resonant unit includes the transmitting coil self-inductance L 1 , resonant capacitor C 1 , the parasitic resistance of the transmitting coil is R s , transmitting coil self-inductance L 1 One end is connected to the MOSFET switch tube S 1 The source, S 2 The drain of 1 One end of the resonant capacitor C1 The other end is connected to the switch tube S 11 The source, S 12 Between the drain electrodes;

[0064] The energy negative feedback unit consists of 4 MOSFET switch tubes S 9 -S 12 and capacitor C i2 Composition, S 9 and S 11 The drain and capacitor C i2 One end of the capacitor C i2 The other end of S 10 and S 12 The source of S 9 The source and S 10 The drain and S 4 The drains of S 11 The source and S 12 The drain and resonant capacitor C 1 One end of the

[0065] The receiving end resonant unit includes the receiving coil self-inductance L r , resonant capacitor C r , the parasitic resistance of the receiving coil is RR, the self-inductance of the receiving coil is L r One end and the resonant capacitor C r Connect together, and the other end is connected to the MOSFET switch tube S 5 The source, S 6 The resonant capacitor C r The other end is connected to the MOSFET switch tube S 7 The source, S 8 Between the drain electrodes;

[0066] The AC-DC conversion unit includes a DC output filter capacitor C o , 1 DC side load resistor R, 4 MOSFET switch tubes S 5 -S 8 Composed of rectifier circuit; output filter capacitor C o After being connected in parallel with the DC side load resistor R, one end is connected to S 5 , S 7 The drain terminals are connected together, and the other end is connected to S 6 , S 8 The source electrodes are connected together.

[0067] The following will take 40W output power as an example to clearly and completely describe the technical solution in the embodiment of the present application.

[0068] The asymmetric resonance parameter design method based on adaptive resonance WPT system includes:

[0069] S1, receiving end resonance parameter C r And a calculation method:

[0070] S11. When the transmitter achieves adaptive resonance, the input voltage and current can always maintain the ZPA (Zero Phase Angle) state, that is, the system's inherent input reactance X in Will no longer affect energy transfer, v 1 The energy that can be injected is only limited by the equivalent resistance R eq Influence.

[0071] S12, using L 1 =a·L r , a>10 design, then

[0072]

[0073] S13, due to L r Due to the size limitation of portable devices, the adjustment range is small and the load R r The parasitic parameter value cannot be changed at will. Refer to the common coil, L r Select 5μH and keep it fixed.

[0074] S14, R eq It will weaken the output power but improve the overall efficiency. Therefore, when designing the parameters, R should be increased as much as possible while ensuring the rated output power of the system. eq To achieve optimal efficiency.

[0075] S15. According to formula A, as long as k is ensured to be the maximum rated value and ω is the minimum rated value, and as long as k is the minimum rated value and ω is the maximum rated value, 40 W of power can be obtained. The system can ensure 40 W output through frequency modulation under rated working conditions.

[0076] Get the R corresponding to 40W power eq It can be calculated by the following formula:

[0077]

[0078] R eq There are two solutions, and the larger value should be chosen to achieve higher efficiency.

[0079] S16. For commercial wireless charging equipment, the rated coupling strength k is generally about 0.6-0.7. In this embodiment, considering that there may be a certain deviation, k∈[0.4,0.7] is set, and the operating frequency is set to [100kHz,150kHz] according to the national interim standard. S With R R Related to the number of turns of the coil, but due to its value and RL With R eq Compared with the above, the influence on the analysis accuracy is limited. Therefore, according to the common coil parasitic parameters, the two are set to 0.3Ω and 0.15Ω respectively. fa is 25.5V, and we can solve for R in formula B. eq is 7.3Ω, and we can use formula A to calculate a and C r Estimate the value range of:

[0080] When k = 0.7, f = 100kHz, a and C r Should meet:

[0081]

[0082] When k = 0.4, f = 150kHz, a and Cr should satisfy:

[0083]

[0084] From this we can get Figure 2 , we can see that when L r After confirmation, C r and a can be freely selected within a certain area. Considering the limited size of the device, it is difficult to stack the capacitor C r For large-scale adjustments, select C r = 180nF single capacitance, further, by Figure 2 It can be seen that a can be designed between 15.7 and 18. According to the formula L 1 =a·L r , when L r =5μH, L 1 The value is between [78.5μH,90μH].

[0085] S2, transmitter resonance parameter C 1 Calculation method:

[0086] When a is determined, L 1 The compensation capacitor C 1 The choice of is more flexible and does not affect the power transmission capability, but it will affect the input reactance X in The way to change S 9 -S 12 The voltage stress on the circuit and the realization conditions of adaptive ZPA. Therefore, C 1 When X in As small as possible and always greater than 0.

[0087] When f = 100kHz, the equivalent reactance X of the receiver at the transmitter with k = 0.4 is eqMinimum, 1.5Ω.

[0088] As long as X in = 0 to ensure V i2 Minimum, the specific formula is as follows:

[0089] X 1 +X eq ≥0|k=0.4,f=100kHz

[0090]

[0091] It can be seen that C 1 The optimal value should be 27.6nF.

[0092] In summary, the asymmetric resonance parameters a,L are completed 1 ,L r ,C 1 ,C r design, thereby completing the lightweight design of the wireless charging receiving end.

[0093] After adopting the asymmetric coil design, the frequency sensitivity of the system is improved. The adaptive resonance method based on energy negative feedback includes:

[0094] 1. The rectifier is the equivalent load R on the left side of the AC-DC conversion unit L :

[0095] 2. Total impedance Z at the receiving end r : ω=2πf

[0096] Where f is the system operating frequency, ω is the angular frequency, and X r With R r Represents Z r The imaginary and real values ​​of .

[0097] 3. According to the mutual inductance model, the total impedance of the receiving end is Z r The equivalent impedance Z at the transmitter eq for:

[0098]

[0099] in,

[0100] 4. Transmitter's own impedance Z 1 for:

[0101] Among them, X 1 With R s Represents Z 1 The imaginary and real values ​​of .

[0102] 5. Combine Z 1 With Z eq , the transmitter resonant current i z1 :

[0103] Z in =Z 1 +Z eq =R in +jX in

[0104] Among them, Z in is the total input impedance, R in With X in are its real and imaginary parts, respectively, v fa is the inverter square wave voltage v 1 The fundamental component of can be solved by Fourier decomposition:

[0105]

[0106] 6. To achieve system resonance, the imaginary part of the total input impedance of the system, i.e., X in is 0, and the following explains Figure 1 How to eliminate X in medium energy negative feedback unit in , so that the system is always in a resonant state.

[0107] Step 1: The inverter, i.e. the DC-AC inverter unit, generates an AC voltage v 1 , and in the resonant network, namely L 1 and C 1 The transmitting end resonant unit constitutes an initial resonant current i z1 . Due to X in The existence of 1 with i z1 There is a phase difference and it is in a detuned state.

[0108] Step 2: Set S reasonably 9 ~S 12 The phase difference between the inverter link provides a low impedance loop for the reactive energy and uses the energy storage capacitor C i2 For storage.

[0109] Step 3: With energy storage, C i2 This will generate a voltage source V i2 , the corresponding square wave AC voltage v2 will generate a new current i in the resonant network v2 , extract the stored energy, and thus convert the original reactive power into active power.

[0110] Step 4: According to the current superposition principle, iz1 with i v2 Will be combined into a total resonant current I' z1 .

[0111] Obviously, there is an inherent energy conservation relationship between the second and third steps:

[0112] Case 1: When X in Increase, i z1 Inject C i2 The reactive power is greater than i v2 When active power is injected into the resonant network, the excess energy is stored in C i2 Medium accumulation, V i2 will increase, that is, i v2 It will be enhanced in the next cycle, thereby converting more reactive power into active power.

[0113] Case 2: When X in Reduce, i z1 Inject C i2 The reactive power is less than i v2 When the active power is injected into the resonant network, i v2 Extract C i2 The accumulated energy causes V i2 Reduce, that is, i v2 The active power injected in the next cycle will be reduced.

[0114] Case 3: When the system is stable, C i2 The energy injected and extracted in a cycle is balanced, V i2 constant.

[0115] Therefore, V i2 The amplitude can be adjusted automatically without any control.

[0116] Therefore, the only requirement is v 2 By solving the appropriate phase, the total current I' z1 With input voltage v 1 Adjust back to ZPA state to achieve detuning correction.

[0117] No. 7, v 2 Phase angle selection

[0118] When detuning correction is not performed, the initial resonant current i z1 :

[0119] S 9 -S 12 and C i2Neither can provide energy for the resonant network and the energy consumed is negligible, so the energy negative feedback unit can only change the input impedance Z in The imaginary part of v2 The values ​​are as follows:

[0120]

[0121] When v 2 The required current i v2 Once known, v can be calculated according to the following formula 2 The fundamental wave v fa2 To do the reverse:

[0122] Thus, v fa2 The amplitude V fa2 , C i2 The terminal voltage V i2 , and v 2 Relative to v 1 The phase α should satisfy the following relationship:

[0123]

[0124] WPT systems for portable devices generally work in X in >0 in the inductive region. Therefore, v 2 Just lag v 1 About 90° can achieve spontaneous detuning correction without any detection and control links.

[0125] like Figure 3 As shown, this embodiment adopts an asymmetric parameter design, the receiving coil is only 5μH, and the transmitting coil is 85μH. Many traditional solutions use a 10uH+10uH symmetrical design (or a nearly symmetrical design). Although the transmitting coil of this embodiment is larger, the receiving coil is the structure that can be truly placed in a portable device, which is conducive to the miniaturization of the receiving end. The power and efficiency comparison of the traditional SS topology and the patented topology are as follows: Figure 3 (a)-(b), the dotted line of the power curve is the traditional solution, and the solid line is the solution of this embodiment. It can be seen that when the same rated power is obtained under different coupling coefficients k by frequency conversion, the efficiency of this solution is constant and much higher than the traditional topology.

[0126] In summary, this embodiment proposes a strongly asymmetric coil design method: L 1 =a·L r , a>10. Where L 1 is the self-inductance of the transmitting coil, L ris the self-inductance of the receiving coil. The voltage at the receiving end is related to the mutual inductance M. By properly selecting a, the required mutual inductance M can be obtained when the self-inductance of the receiving coil is very small, ensuring the output voltage and power. Therefore, a receiving coil with a smaller inductance value can be selected for wireless charging. A smaller inductance value means a smaller parasitic resistance, less energy loss, and less heat.

[0127] This embodiment proposes an adaptive implementation method based on energy negative feedback. After adopting asymmetric coil design, the frequency sensitivity of the system is improved. 9 -S 12 With the inverter link S 1 -S 4 The phase difference between the two can store the reactive energy in the capacitor C. i2 The circuit topology is used to automatically maintain the resonant state when the coupling strength changes, and the required output power can be maintained by changing the frequency. In the coupling strength range of 0.4-0.6 and the frequency range of 100kHz to 150kHz, the system can obtain the required output power, and the transmission efficiency will not fluctuate significantly, and the frequency band utilization and anti-drift capability are greatly improved.

[0128] This embodiment proposes a method for calculating asymmetric resonance parameters: the receiving end resonance parameter C r And a calculation method:

[0129] The equivalent resistance of the receiver at the transmitter is R eq , which is positively correlated with system efficiency, R eq The larger the load, the higher the efficiency. In specific commercial applications, the load R is a fixed value and cannot be changed at will. r When it is fixed at 5μH, it is deduced that the design with L1=a·Lr, a>10, R eq With a and C r Considering the coupling strength of 0.4-0.6 and the frequency range of 100kHz to 150kHz, the system needs to output 40W power. Based on this, a,C r and R eq The relationship surface of a, C r 's selection range.

[0130] Transmitter resonance parameter C 1 Calculation method: When a is determined, L 1 The compensation capacitor C 1 The choice of is more flexible and does not affect the power transmission capability, but it will affect the input reactance X in The way to change S 9 -S 12The voltage stress on the circuit and the realization conditions of adaptive ZPA. Therefore, C 1 When X in As small as possible and always greater than 0. Based on this, C 1 The value range of .

[0131] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A lightweight receiving end method based on an autonomous resonance WPT system, characterized in that: include: The strong asymmetric relationship between the self-inductance of the transmitting coil and the self-inductance of the receiving coil in the construction resonant network; Constructing a first relationship model and an equivalent impedance calculation model, wherein the first relationship model is a relationship model between the equivalent impedance of the receiving end at the transmitting end and the resonant capacitance of the receiving end and the self-inductance of the receiving coil; Based on the equivalent impedance calculation model, obtaining the equivalent impedance at a preset output power; An asymmetric resonance parameter is calculated according to the strong asymmetric relationship, the first relationship model and the equivalent impedance.

2. The lightweight receiving end method based on the autonomous resonance WPT system according to claim 1 is characterized in that: The asymmetric resonance parameters include the multiple a, the transmitting coil self-inductance L1, the receiving coil self-inductance L r , receiving end resonant capacitor C r And the transmitter resonance parameter C1.

3. The lightweight receiving end method based on the autonomous resonance WPT system according to claim 1 is characterized in that: The strong asymmetric relationship is: L1=a·L r ,a>10 Among them, L1 is the self-inductance of the transmitting coil, a is the multiple, L r is the self-inductance of the receiving coil.

4. The lightweight receiving end method based on the autonomous resonance WPT system according to claim 1 is characterized in that: The first relational model is: Among them, R eq is the equivalent resistance of the receiving end at the transmitting end, ω is the angular frequency, M is the mutual inductance, X r With R r Represents the total impedance Z at the receiving end r The imaginary and real values ​​of the , k is the coupling coefficient, L r is the receiving coil self-inductance, C r is the resonant capacitance at the receiving end, and a is the multiple.

5. The receiving end lightweight method based on the autonomous resonance WPT system according to claim 1 is characterized in that: The equivalent impedance calculation model is: Among them, R eq is the equivalent resistance of the receiving end at the transmitting end, R s is the parasitic resistance of the transmitting coil, R L is the equivalent load on the left side of the rectifier, R R is the parasitic resistance of the receiving coil, v fa It is the fundamental component of the inverter square wave voltage v1.

6. The receiving end lightweight method based on the autonomous resonance WPT system according to claim 2 is characterized in that: Calculate the multiple a and the receiving end resonant capacitance C r The method comprises: obtaining a rated coupling coefficient range and a preset operating frequency range, and combining the first relationship model and the equivalent impedance to obtain a receiving end resonant capacitor C r and calculate the design range of the multiple a.

7. The receiving end lightweight method based on the autonomous resonance WPT system according to claim 6 is characterized in that: Calculating the multiple a includes: Obtaining a minimum value of the rated coupling coefficient range and the preset operating frequency range; When the rated coupling coefficient is at the minimum value and the preset operating frequency is at the minimum value, the imaginary part of the total input impedance is made zero, and the compensation capacitor, that is, the transmitting end resonance parameter C1, is calculated.

8. The receiving end lightweight method based on the autonomous resonance WPT system according to claim 6 is characterized in that: The method for calculating the compensation capacitance is: X1+X eq ≥0k=0.4,f=100kHz Among them, X1 represents the imaginary part of the transmitter's own impedance Z1, X eq is the equivalent reactance of the receiving end at the transmitting end, k is the rated coupling strength, f is the operating frequency, C1 is the resonance parameter of the transmitting end, L1 is the self-inductance of the transmitting coil, and ω is the angular frequency.

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