A wireless power transmission system based on single and bipolar interleaved stacked coils

Abstract

The present invention discloses a wireless power transmission system based on single- and bipolar interleaved stacked coils. The transmitting-side coil comprises a single- and bipolar interleaved stacked coil, and a first ferrite placed below the single- and bipolar interleaved stacked coil. The single- and bipolar interleaved stacked coils have two bipolar coils stacked end-to-end in the gap between two series-connected unipolar coils. This system boasts a simple structure, strong scalability, and robust anti-offset capability. It can achieve zero-voltage switching even under conditions with the greatest impact of mutual inductance deviation. Furthermore, it effectively suppresses input harmonics generated by load changes during the charging process.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless power transmission and relates to a wireless power transmission system based on single- and double-pole interleaved stacked coils. Background Art

[0002] With the rapid development of electric vehicles in recent years, charging convenience has become a key factor influencing their widespread adoption. Traditional wired charging methods suffer from issues such as poor interface compatibility, inconvenient operation, and potential safety hazards, making them unable to meet users' demands for convenient and efficient charging. Wireless power transfer (WPT), particularly magnetically coupled resonant wireless charging, offers a new solution for electric vehicle charging. This technology utilizes the principle of electromagnetic induction to achieve contactless power transmission, offering advantages such as ease of operation, high safety, and strong environmental adaptability, effectively enhancing the user experience.

[0003] At the same time, coil offset has become a major bottleneck limiting the in-depth application of WPT technology. Therefore, a variety of coupling mechanisms and compensation topologies with anti-offset capabilities have been proposed to address the adverse effects of offset. To further improve the anti-offset capability of wireless power transmission systems, the optimization design of coupling mechanisms and compensation topologies has become a hot topic of current research. These methods can fully utilize the structural characteristics of the coupling mechanism and the output characteristics of the compensation topology. However, this research currently faces problems such as complex system structure and the influence of load and mutual inductance on the resonant state. At the same time, when designing wireless power transmission systems, there are also issues such as the compactness of the coupling mechanism, the utilization of the coil, the ability to achieve zero voltage switching (ZVS), and the ability to adapt to load changes. Summary of the Invention

[0004] The object of the present invention is to provide a wireless power transmission system which has strong anti-offset capability, realizes zero voltage switching, and has good suppression effect on input harmonics generated by load changes.

[0005] The technical solution for achieving the purpose of the present invention is: a wireless power transmission system based on a single- and bipolar interleaved stacked coil, wherein the transmitting side coil includes a single- and bipolar interleaved stacked coil, and a first ferrite placed on the lower side of the single- and bipolar interleaved stacked coil, wherein the single- and bipolar interleaved stacked coil places two bipolar coils stacked end to end in the gap between two series-connected monopolar coils, specifically:

[0006] The monopolar and bipolar interleaved stacked coil includes a first bipolar coil, a second bipolar coil, a first unipolar coil and a second unipolar coil. The first bipolar coil and the second bipolar coil are both composed of two small rectangular coils, wherein: the two small rectangular coils of the first bipolar coil are located on both sides of the first unipolar coil, and the two small rectangular coils of the second bipolar coil are located on both sides of the second unipolar coil. The two small rectangular coils in the gap between the first unipolar coil and the second unipolar coil completely overlap; after the first unipolar coil and the second unipolar coil are connected in series, they are connected in parallel with the second bipolar coil, and the entire parallel circuit is then connected in series with the first bipolar coil.

[0007] Furthermore, the length of the first unipolar coil and the second unipolar coil is a, and the width is b; the first bipolar coil and the second bipolar coil are both composed of two small rectangular coils of the same size and number of turns, the length of the small rectangular coil in the bipolar coil is wl, the width is e, and the interval between the two small rectangular coils in the bipolar coil is sl.

[0008] Furthermore, the first unipolar coil is placed in the middle of the separation of the first bipolar coil and the width centers are aligned; the second unipolar coil is placed in the middle of the separation of the second bipolar coil and the width centers are aligned; the small rectangular coil on the right side of the first bipolar coil and the small rectangular coil on the left side of the second bipolar coil are overlapped and stacked, and at this time the interval between the first unipolar coil and the second unipolar coil is g.

[0009] Furthermore, the transmitting side also includes a DC source, an inverter filter circuit, and a compensation capacitor C p , compensation capacitor C a ,in:

[0010] The DC source is connected to the input side of the inverter filter circuit; the compensation capacitor C p The first unipolar coil and the second unipolar coil are connected in series to form branch 1, the second bipolar coil and the compensation capacitor C a The compensation capacitor C p Connected to the second bipolar coil, compensation capacitor C a Connected to the second unipolar coil; the first bipolar coil and the compensation capacitor C p Connected to the connection point of the second bipolar coil, the other end of the first bipolar coil and the compensation capacitor C a The connection point with the second unipolar coil is connected to the output side of the inverter filter circuit.

[0011] Furthermore, the receiving side includes a receiving coil, a secondary compensation capacitor C s , rectifier and filter circuit, variable load and second ferrite, wherein:

[0012] The receiving coil is placed on the lower side of the second ferrite; the receiving coil and the secondary compensation capacitor C s Series; secondary compensation capacitor C s The other end is connected to the input side of the rectifier and filter circuit; the output side of the rectifier and filter circuit is connected to the variable load.

[0013] Furthermore, the first unipolar coil, the second unipolar coil, the first bipolar coil, the second bipolar coil and the receiving coil are all wound with Litz wire with parameters of 0.1mm*200 strands; the first ferrite and the second ferrite are made of ferrite material with model TDK-PC95 and material of Mn-Zn.

[0014] Furthermore, the design process is as follows:

[0015] Step 1: Initialize parameters based on the actual space requirements of the wireless power transmission system, including: the length a and width b of the unipolar coil, the length c and width d of the receiving coil, the width e of the small rectangular coil in the bipolar coil, the transmission distance h between the transmitting and receiving sides, the spacing sl between the two small rectangular coils in the bipolar coil, and the spacing g between the first and second unipolar coils.

[0016] Step 2: obtain the fluctuation curve of the mutual inductance of the first and second unipolar coils when the receiving coil moves through simulation, confirm the maximum compensation mutual inductance value that meets the wireless power transmission system based on the fluctuation curve, and thus select the length wl and number of turns of the small rectangular coil in the bipolar coil;

[0017] Step 3: When the receiving coil moves to the midpoint of the gap between the first unipolar coil and the second unipolar coil, the corresponding relative mutual inductance sum M is p1,(a+g) +M p2,(a+g) Minimum, where M p1,(a+g) is the mutual inductance between the first unipolar coil and the receiving coil; M p2,(a+g) is the mutual inductance between the second unipolar coil and the receiving coil, M p1,0 、M p2,0 is the mutual inductance corresponding to a+g=0;

[0018] Determine the maximum value M of the mutual inductance between the first and second bipolar coils and the receiving coil ai,max Whether it meets:

[0019]

[0020] Where i=1,2;

[0021] If the above equation is not satisfied, return to step 1 and adjust the parameters of the unipolar coil, the receiving coil, and the interval g between the first unipolar coil and the second unipolar coil;

[0022] Step 4: According to the interval g between the first unipolar coil and the second unipolar coil and the length wl of the small rectangular coil in the bipolar coil, adjust the interval sl between the two small rectangular coils in the bipolar coil to meet ;

[0023] Step 5: To prevent errors in the coil manufacturing process from significantly affecting the resonance of the wireless power transmission system, verify whether the sum of the mutual inductance between the two bipolar coils and the receiving coil exceeds the error range allowed by the wireless power transmission system:

[0024]

[0025] Among them, M a1 is the mutual inductance between the first bipolar coil and the receiving coil; M a2 is the mutual inductance between the second bipolar coil and the receiving coil; M ero is the maximum value of the sum of the mutual inductances of the two bipolar coils and the receiving coil;

[0026] If not, return to step 1 to redefine the parameters and design the coil;

[0027] Step 6: Calculate the equivalent mutual inductance M of the coupling mechanism of the wireless power transmission system at this time eq , expressed as:

[0028]

[0029] Among them, M p1 is the mutual inductance between the first unipolar coil and the receiving coil; M p2 is the mutual inductance between the second unipolar coil and the receiving coil;

[0030] At this time, the bipolar coil parameters should satisfy the following formula:

[0031]

[0032] Among them, M eq,max is the maximum value of the equivalent mutual inductance of the coupling mechanism of the wireless power transmission system; M eq,min is the minimum value of the equivalent mutual inductance of the coupling mechanism of the wireless power transmission system;

[0033] If not, return to step 2 and reselect the length wl and number of turns of the two small rectangular coils in the bipolar coil;

[0034] Step 7: Build a wireless power transmission system based on the single and bipolar interleaved stacked coils designed in steps 1 to 6.

[0035] Compared with the prior art, the present invention has the following significant advantages:

[0036] (1) The wireless power transmission system based on single and bipolar interleaved stacked coils has a simple topology and strong scalability, which can meet the needs of different application scenarios.

[0037] (2) The wireless power transmission system based on the single-polarity and bipolarity interleaved stacked coils uses the method of multiplexing the single-polarity coils and the bipolarity coils to improve the utilization rate of the coils.

[0038] (3) Based on the wireless power transmission system of single and bipolar interleaved stacked coils, the monopolar coil is combined with the bipolar coil and the rectangular coil to improve the compactness of the overall coil structure.

[0039] (4) In the wireless power transmission system based on single- and bipolar interleaved stacked coils, when the receiving coil moves laterally, the equivalent mutual inductance and its fluctuation rate of the proposed coupling mechanism change little, proving that it has strong anti-offset capability in the lateral direction.

[0040] (5) In the wireless power transmission system based on single-pole and bipolar interleaved stacked coils, when the length of the receiving coil changes, the equivalent mutual inductance and its fluctuation rate of the proposed coupling mechanism change little, and have good compatibility with the change of the receiving coil length. Therefore, the mutual inductance fluctuation caused by the coil length error in the actual manufacturing process can be effectively avoided.

[0041] (6) Based on the wireless power transmission system of single and bipolar interleaved stacked coils, the proposed single and bipolar interleaved stacked coil structure can ensure the constant current of the unipolar coil as well as the ideal zero power absorption and constant output voltage characteristics.

[0042] (7) In the wireless power transmission system based on single- and bipolar interleaved stacked coils, when the proposed single- and bipolar interleaved stacked coil structure is most affected by the mutual inductance deviation, the input impedance angle of the system can still be maintained at a small value, achieving ideal ZVS.

[0043] (8) Based on the wireless power transmission system of single and bipolar interleaved stacked coils, the proposed wireless power transmission system has a good suppression effect on the input harmonics generated by load changes during the charging process. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 A three-dimensional structural diagram of the single-pole and bipolar interleaved stacked coils and the receiving coil of the present invention;

[0045] Figure 2 This is an equivalent circuit diagram of the wireless power transmission system based on single and bipolar interleaved stacked coils of the present invention;

[0046] Figure 3 It is the fundamental wave decoupling equivalent circuit of the wireless power transmission system of the present invention;

[0047] Figure 4A flow chart of the design method of the present invention;

[0048] Figure 5 This is a diagram showing the change in equivalent mutual inductance of the coupling mechanism of the wireless power transmission system when the receiving coil of the present invention moves laterally;

[0049] Figure 6 This is a graph showing the fluctuation rate of the equivalent mutual inductance of the coupling mechanism of the wireless power transmission system when the receiving coil of the present invention moves laterally;

[0050] Figure 7 This is a simulated waveform diagram of the output voltage and current of the full-bridge inverter when the wireless power transmission system of the present invention is most affected by the mutual inductance deviation;

[0051] Figure 8 This is a diagram showing the experimental and simulation results of the secondary side receiving voltage when the receiving coil of the present invention moves laterally;

[0052] Figure 9 The load resistor R L =10Ω, full-bridge inverter output voltage and current measurement experiment diagram;

[0053] Figure 10 The load resistor R L =2Ω, full-bridge inverter output voltage and current measurement experiment diagram;

[0054] Figure 11 The load resistor R L =5Ω, full-bridge inverter output voltage and current measurement experiment diagram. DETAILED DESCRIPTION

[0055] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0056] The present invention provides a wireless power transmission system based on single- and bipolar interleaved stacked coils. The transmitting-side coil is composed of single- and bipolar interleaved stacked coils. Two bipolar coils stacked end to end are placed in the gap between the two series-connected monopolar coils. The first bipolar coil is connected in series with the two monopolar coils and then in parallel with the second bipolar coil. When the receiving-side coil moves laterally, the spatial compensation effect of the two bipolar coils can keep the output voltage change small. At the same time, the two bipolar coils also serve as compensation inductors, enabling the entire wireless power transmission system to achieve zero-voltage switching and suppress input harmonics generated by load changes.

[0057] Figure 1This is a three-dimensional structure diagram of the monopolar and bipolar interleaved stacked coils and the receiving coil, where 1 is the first monopolar coil; 2 is the second monopolar coil; 3 is the first bipolar coil; 4 is the second bipolar coil; 5 is the receiving rectangular coil; 6 is the first ferrite; and 7 is the second ferrite.

[0058] The proposed single- and bipolar interleaved stacked coil includes a first single-polarity coil, a second single-polarity coil, a first bipolarity coil, and a second bipolarity coil; the length of the first single-polarity coil and the second single-polarity coil is a, and the width is b; the first bipolarity coil and the second bipolarity coil are both composed of two small rectangular coils of the same size and number of turns wound with the same wire, the length of the small rectangular coil in the bipolar coil is wl, the width is e, and the interval between the two small rectangular coils in the bipolar coil is sl.

[0059] like Figure 1 As shown, the first unipolar coil is placed at the middle of the separation of the first bipolar coil and the width centers are aligned; the second unipolar coil is placed at the same position of the second bipolar coil; the small rectangular coil on the right side of the first bipolar coil and the small rectangular coil on the left side of the second bipolar coil are overlapped and stacked, and the interval between the first unipolar coil and the second unipolar coil is g; the single and bipolar staggered stacked coils are placed on the upper side of the first ferrite.

[0060] The first unipolar coil, the second unipolar coil, the first bipolar coil and the second bipolar coil are all wound with Litz wire with parameters of 0.1mm*200 strands; the first ferrite is made of ferrite material with model TDK-PC95 and material of Mn-Zn.

[0061] The transmitting side also includes a DC source, an inverter filter circuit and a compensation capacitor C p 、C a , the compensation capacitor C p , the first unipolar coil, the second unipolar coil are connected in series with the second bipolar coil and the compensation capacitor C a The structure formed in series is connected in parallel and then connected in series with the first bipolar coil. The formed overall structure is connected to the output side of the inverter filter circuit; the DC source is connected to the input side of the inverter filter circuit.

[0062] The receiving side includes the receiving coil, the secondary compensation capacitor C s , rectifier filter circuit and variable load, the receiving coil has a length of c and a width of d and is placed on the lower side of the second ferrite; the receiving coil and the secondary compensation capacitor C s In series; the secondary compensation capacitor C s The output side of the rectifier and filter circuit is connected to a variable load.

[0063] The receiving coil is wound with a Litz wire with parameters of 0.1mm*200 strands; the second ferrite is made of a ferrite material with a model of TDK-PC95 and a material of Mn-Zn.

[0064] Next, the performance of the wireless power transmission proposed in the present invention is analyzed.

[0065] like Figure 2 As shown, L1 and L2 are the equivalent inductances of the first bipolar coil and the second bipolar coil respectively. p1 , L p2 The equivalent inductance of the first unipolar coil and the second unipolar coil, L s is the equivalent inductance of the receiving coil; C p 、C s They are the compensation capacitors at the unipolar coil and the receiving coil, C a is the compensation capacitor on branch L2; U DC 、C d1 are the DC input voltage and input side filter capacitor, R L 、U out 、C d2 are the variable load resistance, voltage and output side filter capacitor respectively; Q1, Q2, Q3 and Q4 are the switch tubes in the inverter filter circuit; D1, D2, D3 and D4 are the diodes in the rectifier filter circuit; M a1 、M a2 、M p1 、M p2 L1, L2, L p1 , L p2 and L s Mutual inductance between 12 is the mutual inductance between L1 and L2; M p12 For L p1 and L p2 Mutual inductance between a1p2 For L1 and L p2 Mutual inductance between a2p1 For L2 and L p1 Mutual induction between.

[0066] The inverter filter circuit and rectifier filter circuit used in the present invention are full-bridge inverter and full-bridge rectifier respectively. Therefore, the fundamental wave approximation analysis method is adopted. The effective value of the fundamental wave voltage output by the full-bridge inverter is U in , the equivalent impedance of the load resistor R eq They can be expressed as:

[0067]

[0068]

[0069] right Figure 2 The circuit diagram shown is used for decoupling, and its fundamental wave decoupling equivalent circuit is as follows Figure 3 As shown, where L 1e , L 2e are the equivalent inductances of L1 and L2 respectively, L pe For L p1 , L p2 The equivalent inductance of M is L pe and L s The equivalent mutual inductance formed. L 1e , L 2e and L pe , M can be obtained by the following formula:

[0070]

[0071] Ignoring the height difference between the unipolar coil and the bipolar coil due to overlap, the M of the coupling mechanism is a1p2 、M a2p1 The sizes are equal, so we know that L 1e , L 2e Equal. And M 12 、M p1p2 It is not affected by external factors such as receiving coil offset, load parameter changes, unipolar coil switching, etc., so L 1e , L 2e and L pe Can be regarded as L1, L2 and L p1 +L p2 The equivalent inductance of Figure 3 The fundamental wave decoupling equivalent circuit in the application of KCL and KVL laws can be expressed as follows:

[0072]

[0073] Where U in is the effective value of the fundamental voltage output by the full-bridge inverter, ω is the frequency of the wireless power transmission system, I in is the effective value of the fundamental current output by the full-bridge inverter, I p , I s are the fundamental current effective values ​​of the unipolar coil and the receiving coil respectively, and I2 is the fundamental current effective value of the primary side L2 parallel branch. p 、C s The value of satisfies the following conditions:

[0074]

[0075] According to the above conditions, the input impedance Z of wireless power transmission can be obtained at this time. in And the voltage gain ratio G uuThe expressions are as follows:

[0076]

[0077]

[0078] Among them U o In order to make the structure proposed by the present invention meet the resonance condition of the wireless power transmission system and maintain the characteristics of the constant current of the unipolar coil, the two additional compensation mutual inductances M are designed to a1 、M a2 The following conditions are met:

[0079]

[0080] Let M a1 =M a , then M a2 =-M a At this time I p 、Z in , G uu And the system output power P o They can be divided as follows:

[0081]

[0082]

[0083]

[0084]

[0085] According to the above formula, the present invention can ensure the constant current of the unipolar coil as well as the ideal ZPA and constant output voltage characteristics.

[0086] The additional mutual inductance M of L1, L2 and the receiving coil a1 、M a2 Together, they provide an additional energy transmission channel for wireless power transmission, compensating for the M fluctuation problem caused by the change in the position of the receiving coil, and equivalently increasing the mutual inductance value of wireless power transmission. Therefore, when the receiving coil is offset, the additional mutual inductance M a The increase in the equivalent mutual inductance of the system maintains relative stability, which can offset the problem of transmission performance degradation caused by the offset.

[0087] For the system in actual application, due to manufacturing errors and construction errors, it may not always be possible to guarantee M a1 +M a2 = 0, the following analysis of the structure proposed by the present invention for the practical application of Ma1 、M a2 The robustness of the system when deviation occurs, that is, analyzing the a1 、M a2 The effect of the deviation on the resonant state and output voltage of the proposed wireless power transmission is expressed by the input impedance angle θ and the voltage gain ratio G uu The resonant state and output voltage of the system at this time are described as follows:

[0088]

[0089] in , G uu_ero Due to M a1 、M a2 The input impedance angle and voltage gain ratio of the wireless power transmission system when the deviation is unequal; G uu * It represents the per-unit value between the voltage gain ratio and the ideal value due to deviation; k is the deviation coefficient of the system at this time.

[0090] From the above formula, we can get M a1 、M a2 Deviation from the ideal setting value, that is, when |M a1 +M a2 When |≠0, Not equal to 0 and Less than 1. When the parameters of the wireless power transmission system are determined, k is only related to MM a2 、|M a1 +M a2 | and R during charging eq changes related to .

[0091] It is used to describe the degree of deviation of the system output voltage at this time. The expression of the deviation coefficient k is as follows:

[0092]

[0093] In order to make the wireless power transmission system work under the ideal ZVS condition, the input impedance angle Should be kept at (0, ), M a1 、M a2 Deviation caused by satisfy:

[0094]

[0095] in 、 Due to M a1 、M a2 Possible inequality The maximum and minimum values, combined with the previous formula, are: 、 satisfy:

[0096]

[0097] Considering the maximum possible error, the wireless power transmission system maintains the ideal ZVS condition under M a1 +M a2 The value range is:

[0098]

[0099] where R eq min is the minimum value of the equivalent impedance of the load resistance; is the maximum value of the input impedance angle.

[0100] In order to ensure the constant voltage output characteristics of the wireless power transmission system, it is given ,in is the threshold, so we have:

[0101]

[0102] In summary, it can be determined that under the condition of maintaining ideal ZVS and constant output characteristics, the allowed M a1 +M a2 The maximum value range of the deviation is:

[0103]

[0104] Among them, M ero M a1 +M a2 The maximum value of L f is the equivalent inductance of the compensation inductor.

[0105] The wireless power transmission system can be obtained is 7°, δ is 0.995. Build a simulink simulation model and take the load resistance as 10Ω. M a2 Maximum value M a2max = -1.2 M a1 , the full-bridge inverter output voltage and current simulation waveforms are as follows Figure 7 As shown. Figure 7 It can be seen that when the wireless power transmission system proposed by the present invention is most affected by the mutual inductance deviation, the input impedance angle of the wireless power transmission system can still be maintained at a small value, less than the set target of 7°, and ideal ZVS can be achieved.

[0106] A specific design method for a wireless power transmission system based on single and bipolar interleaved stacked coils, such as Figure 4 The specific steps are as follows:

[0107] Step 1: Initialize parameters based on the actual space requirements of the wireless power transmission system, including: the length a and width b of the unipolar coil, the length c and width d of the receiving coil, the width e of the small rectangular coil in the bipolar coil, the transmission distance h between the transmitting and receiving sides, the spacing sl between the two small rectangular coils in the bipolar coil, and the spacing g between the first and second unipolar coils.

[0108] Step 2: obtain the fluctuation curve of the mutual inductance of the first and second unipolar coils when the receiving coil moves through simulation, confirm the maximum compensation mutual inductance value that meets the wireless power transmission system based on the fluctuation curve, and thus select the length wl and number of turns of the small rectangular coil in the bipolar coil;

[0109] Step 3: When the receiving coil moves to the midpoint of the gap between the first unipolar coil and the second unipolar coil, the corresponding relative mutual inductance sum M is p1,(a+g) +M p2,(a+g) Minimum, where M p1,(a+g) is the mutual inductance between the first unipolar coil and the receiving coil; M p2,(a+g) is the mutual inductance between the second unipolar coil and the receiving coil, M p1,0 、M p2,0 is the mutual inductance corresponding to a+g=0;

[0110] Determine the maximum value M of the mutual inductance between the first and second bipolar coils and the receiving coil ai,max Whether it meets:

[0111]

[0112] Where i=1,2;

[0113] If the above equation is not satisfied, return to step 1 and adjust the parameters of the unipolar coil, the receiving coil, and the interval g between the first unipolar coil and the second unipolar coil;

[0114] Step 4: According to the interval g between the first unipolar coil and the second unipolar coil and the length wl of the small rectangular coil in the bipolar coil, adjust the interval sl between the two small rectangular coils in the bipolar coil to meet ;

[0115] Step 5: To prevent errors in the coil manufacturing process from significantly affecting the resonance of the wireless power transmission system, verify whether the sum of the mutual inductance between the two bipolar coils and the receiving coil exceeds the error range allowed by the wireless power transmission system:

[0116]

[0117] Among them, M a1 is the mutual inductance between the first bipolar coil and the receiving coil; M a2 is the mutual inductance between the second bipolar coil and the receiving coil; M ero is the maximum value of the sum of the mutual inductances of the two bipolar coils and the receiving coil;

[0118] If not, return to step 1 to redefine the parameters and design the coil;

[0119] Step 6: Calculate the equivalent mutual inductance M of the coupling mechanism of the wireless power transmission system at this time eq , expressed as:

[0120]

[0121] Among them, M p1 is the mutual inductance between the first unipolar coil and the receiving coil; M p2 is the mutual inductance between the second unipolar coil and the receiving coil;

[0122] At this time, the bipolar coil parameters should satisfy the following formula:

[0123]

[0124] Among them, M eq,max is the maximum value of the equivalent mutual inductance of the coupling mechanism of the wireless power transmission system; M eq,min is the minimum value of the equivalent mutual inductance of the coupling mechanism of the wireless power transmission system;

[0125] If not, return to step 2 and reselect the length wl and number of turns of the small rectangular coil in the bipolar coil;

[0126] Step 7: Build a wireless power transmission system based on the single and bipolar interleaved stacked coils designed in steps 1 to 6.

[0127] Example

[0128] In order to verify the effectiveness of the scheme of the present invention, an experimental design was carried out.

[0129] The experimental parameter values ​​are shown in Table 1.

[0130] Table 1 System experimental parameter values

[0131] parameter Value Unipolar coil length a 150mm Unipolar coil width b 100mm Receiving coil length c 100mm Receiving coil width d 150mm Width e of small rectangular coil in bipolar coil 100mm Length of small rectangular coil in bipolar coil wl 100mm The interval between the two small rectangular coils in the bipolar coil is sl 135mm Transmission distance between the transmitting side and the receiving side h 100mm The first unipolar coil and the second unipolar coil are spaced apart by g 75mm The first unipolar coil, the second unipolar coil, the first bipolar coil, the second bipolar coil and the receiving coil wire diameter 2mm Unipolar coil turns 5 Number of turns of small rectangular coil in bipolar coil 4 Receiving coil turns 7 Wireless power transmission system frequency ω 85kHz Unipolar coil self-inductance 31.4μH Receiving coil self-inductance 56μH Bipolar coil self-inductance 17.2μH <![CDATA[Compensation capacitor C p > 74.8nF <![CDATA[Compensation capacitor C a > 144.3nF <![CDATA[Secondary compensation capacitor C s > 68.5nF

[0132] In this embodiment, the equivalent mutual inductance M of the coupling mechanism of the wireless power transmission system proposed in the present invention is eq and its volatility M flua The results are as follows Figure 5 、 Figure 6 shown.

[0133] from Figure 5 and Figure 6 It can be seen from the figure that for a certain interval g between the first and second unipolar coils, even if the length of the receiving coil changes, the value of the equivalent mutual inductance and its fluctuation rate change very little. The equivalent mutual inductance of the proposed coupling mechanism can remain stable when the position of the receiving coil changes along the lateral direction, and the fluctuation rate does not exceed 5%. Therefore, the equivalent structure of the transmitting-side coil of the proposed coupling mechanism has good compatibility with changes in the length of the receiving coil.

[0134] The feasibility and advancement of the present invention are verified through experiments. Figure 8 The secondary side receiving voltage experimental and simulation results are shown when the receiving coil of the present invention moves horizontally. Figure 8 It can be seen from the figure that the experimental and simulation results are close, and the wireless power transmission system proposed in the present invention has good anti-deviation characteristics.

[0135] When the load resistance changes, the output voltage and current measurement results of the full-bridge inverter are as follows: Figure 9 、 Figure 10 and Figure 11 As shown in Figure 3, the resonant state of the proposed wireless power transfer system is basically unaffected by the change of load resistance.

[0136] In general, the present invention proposes a wireless power transmission system based on single and bipolar interleaved stacked coils, and proposes a corresponding design method based on the system. The wireless power transmission system has strong resistance to lateral offset and can ensure that the system achieves zero voltage switching and is not affected by load changes.

[0137] It should be noted that while the above description provides an ideal embodiment, it is not intended to limit the scope of protection of the present invention. Under the guidance of the present invention, those skilled in the art may make appropriate substitutions or adjustments without exceeding the scope of protection defined by the claims of the present invention. The scope of protection of the present invention should be strictly determined in accordance with the appended claims.

Claims

1. A wireless power transmission system based on single and double pole interleaved stacked coils, characterized in that: The transmitting side coil includes a single-pole and bipolar interleaved stacked coil, and a first ferrite placed on the lower side of the single-pole and bipolar interleaved stacked coil. The single-pole and bipolar interleaved stacked coil has two bipolar coils stacked end to end in the gap between two series-connected monopolar coils. Specifically: The monopolar and bipolar interleaved stacked coil includes a first bipolar coil, a second bipolar coil, a first unipolar coil and a second unipolar coil. The first bipolar coil and the second bipolar coil are both composed of two small rectangular coils, wherein: the two small rectangular coils of the first bipolar coil are located on both sides of the first unipolar coil, and the two small rectangular coils of the second bipolar coil are located on both sides of the second unipolar coil. The two small rectangular coils in the gap between the first unipolar coil and the second unipolar coil completely overlap; after the first unipolar coil and the second unipolar coil are connected in series, they are connected in parallel with the second bipolar coil, and the entire parallel circuit is then connected in series with the first bipolar coil.

2. The wireless power transmission system based on single and bipolar interleaved stacked coils according to claim 1, characterized in that: The length of the first unipolar coil and the second unipolar coil is a, and the width is b. The first bipolar coil and the second bipolar coil are both composed of two small rectangular coils of the same size and number of turns. The length of the small rectangular coil in the bipolar coil is wl , the width is e, and the interval between the two small rectangular coils in the bipolar coil is sl .

3. The wireless power transmission system based on single and bipolar interleaved stacked coils according to claim 2, characterized in that: The first unipolar coil is placed in the middle of the separation of the first bipolar coil and the width centers are aligned; the second unipolar coil is placed in the middle of the separation of the second bipolar coil and the width centers are aligned; the small rectangular coil on the right side of the first bipolar coil and the small rectangular coil on the left side of the second bipolar coil are overlapped and stacked, and the interval between the first unipolar coil and the second unipolar coil is g.

4. The wireless power transmission system based on single and bipolar interleaved stacked coils according to claim 3, characterized in that: The transmitting side also includes a DC source, an inverter filter circuit, and a compensation capacitor C p , compensation capacitor C a ,in: The DC source is connected to the input side of the inverter filter circuit; the compensation capacitor C p The first unipolar coil and the second unipolar coil are connected in series to form branch 1, the second bipolar coil and the compensation capacitor C a The compensation capacitor C p Connected to the second bipolar coil, compensation capacitor C a Connected to the second unipolar coil; the first bipolar coil and the compensation capacitor C p Connected to the connection point of the second bipolar coil, the other end of the first bipolar coil and the compensation capacitor C a The connection point with the second unipolar coil is connected to the output side of the inverter filter circuit.

5. The wireless power transmission system based on single and double polar interleaved stacked coils according to claim 4, characterized in that: The receiving side includes the receiving coil, the secondary compensation capacitor C s , rectifier and filter circuit, variable load and second ferrite, wherein: The receiving coil is placed on the lower side of the second ferrite; the receiving coil and the secondary compensation capacitor C s Series; secondary compensation capacitor C s The other end and the other end of the receiving coil are connected to the input side of the rectifier and filter circuit; the output side of the rectifier and filter circuit is connected to the variable load.

6. The wireless power transmission system based on single and double polarity interleaved stacked coils according to claim 5, characterized in that: The first unipolar coil, the second unipolar coil, the first bipolar coil, the second bipolar coil and the receiving coil are all wound with Litz wire with parameters of 0.1mm*200 strands; the first ferrite and the second ferrite are made of ferrite material with model TDK-PC95 and material of Mn-Zn.

7. The wireless power transmission system based on single and double polarity interleaved stacked coils according to claim 6, characterized in that: The design process is as follows: Step 1: Initialize the parameters according to the actual space requirements of the wireless power transmission system, including: the length a and width b of the unipolar coil, the length c and width d of the receiving coil, the width e of the small rectangular coil in the bipolar coil, the transmission distance h between the transmitting side and the receiving side, and the distance between the two small rectangular coils in the bipolar coil. sl , the first unipolar coil and the second unipolar coil are spaced apart by g; Step 2: Get the fluctuation curve of the mutual inductance of the first and second unipolar coils when the receiving coil moves through simulation. According to the fluctuation curve, determine the maximum compensation mutual inductance value that satisfies the wireless power transmission system, and then select the length of the small rectangular coil in the bipolar coil. wl and number of turns; Step 3: When the receiving coil moves to the midpoint of the gap between the first unipolar coil and the second unipolar coil, the corresponding relative mutual inductance sum M is p1,(a+g) +M p2,(a+g) Minimum, where M p1,(a+g) is the mutual inductance between the first unipolar coil and the receiving coil; M p2,(a+g) is the mutual inductance between the second unipolar coil and the receiving coil, M p1,0 、M p2,0 is the mutual inductance corresponding to g=0; Determine the maximum value M of the mutual inductance between the first and second bipolar coils and the receiving coil ai,max Whether it meets: ； Where i=1,2; If the above equation is not satisfied, return to step 1 and adjust the parameters of the unipolar coil, the receiving coil, and the interval g between the first unipolar coil and the second unipolar coil; Step 4: According to the interval g between the first unipolar coil and the second unipolar coil and the length of the small rectangular coil in the bipolar coil wl , adjust the distance between the two small rectangular coils in the bipolar coil at this time sl ,satisfy ; Step 5: To prevent errors in the coil manufacturing process from affecting the resonance of the wireless power transfer system, verify whether the sum of the mutual inductance between the two bipolar coils and the receiving coil exceeds the error range allowed by the wireless power transfer system: ； Among them, M a1 is the mutual inductance between the first bipolar coil and the receiving coil; M a2 is the mutual inductance between the second bipolar coil and the receiving coil; M ero is the maximum value of the sum of the mutual inductances of the two bipolar coils and the receiving coil; If not, return to step 1 to redefine the parameters and design the coil; Step 6: Calculate the equivalent mutual inductance M of the coupling mechanism of the wireless power transmission system at this time eq , expressed as: ； Among them, M p1 is the mutual inductance between the first unipolar coil and the receiving coil; M p2 is the mutual inductance between the second unipolar coil and the receiving coil; At this time, the bipolar coil parameters should satisfy the following formula: ； Among them, M eq,max is the maximum value of the equivalent mutual inductance of the coupling mechanism of the wireless power transmission system; M eq,min is the minimum value of the equivalent mutual inductance of the coupling mechanism of the wireless power transmission system; If not, return to step 2 and reselect the length of the small rectangular coil in the bipolar coil. wl and number of turns; Step 7: Build a wireless power transmission system based on the single and bipolar interleaved stacked coils designed in steps 1 to 6.

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