Wireless power transmission system based on single-pole and double-pole staggered and stacked coils

Abstract

The invention discloses a wireless electric energy transmission system based on single-pole and double-pole staggered stacked coils, and the system is characterized in that a transmitting side coil comprises the single-pole and double-pole staggered stacked coils and a first ferrite placed at the lower side of the single-pole and double-pole staggered stacked coils; according to the unipolar and bipolar staggered stacked coil, two bipolar coils stacked end to end are placed in a gap between two unipolar coils connected in series. According to the invention, the structure is simple, the expansibility is high, the anti-offset capability is high, zero-voltage switching can be realized under the condition that the influence of mutual inductance deviation is maximum, and in addition, an input harmonic wave generated by load change in the charging process is well inhibited.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless power transfer, and relates to a wireless power transfer system based on a single and bipolar interleaved stacked coil. Background Art

[0002] In recent years, with the rapid development of electric vehicles, charging convenience has become a key factor affecting their popularization. Traditional wired charging methods have problems such as poor interface compatibility, inconvenient operation, and safety hazards, and it is difficult to meet the user's demand for convenient and efficient charging. Wireless power transfer technology (WPT), especially magnetic coupling resonant wireless charging technology, provides a new solution for electric vehicle charging. This technology uses the principle of electromagnetic induction to achieve power transfer in a non-contact manner, and has advantages such as convenient operation, high safety, and strong environmental adaptability, which can effectively improve the user experience.

[0003] At the same time, coil misalignment has become a major bottleneck restricting the in-depth application of WPT technology. Therefore, various coupling mechanisms and compensation topologies with anti-misalignment capabilities have been successively proposed to solve the adverse effects caused by misalignment. In order to further improve the anti-misalignment ability of the wireless power transfer system, the combined optimization design of the coupling mechanism and the compensation topology has become a current research hotspot. These methods can make full use of the structural characteristics of the coupling mechanism and the output characteristics of the compensation topology. However, the current research still faces problems such as complex system structure, resonance state affected by load and mutual inductance changes. At the same time, there are also problems such as the compactness of the coupling mechanism, the utilization rate of the coil, the ability to achieve zero voltage switching (ZVS), and adaptability to load changes in the design of the wireless power transfer system. Summary of the Invention

[0004] The purpose of the present invention is to provide a wireless power transfer system with strong anti-misalignment ability, zero voltage switching, and 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 transfer system based on a single and bipolar interleaved stacked coil. The transmitting side coil includes a single and bipolar interleaved stacked coil and a first ferrite placed under the single and bipolar interleaved stacked coil. Among them, two bipolar coils stacked end to end are placed in the gap between two series-connected unipolar coils of the single and bipolar interleaved stacked coil. Specifically:

[0006] The single - and double - pole 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. Specifically: 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] Further, 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 \(wl\) and the width is \(e\), and the interval between the two small rectangular coils in the bipolar coil is \(sl\).

[0008] Further, the first unipolar coil is placed at the separation middle of the first bipolar coil and is width - center - aligned; the second unipolar coil is placed at the separation middle of the second bipolar coil and is width - center - aligned; the right - hand small rectangular coil of the first bipolar coil and the left - hand small rectangular coil of the second bipolar coil are stacked and overlapped. At this time, the interval between the first unipolar coil and the second unipolar coil is \(g\).

[0009] Further, the transmitting side also includes a DC source, an inverter - filter circuit, and compensation capacitors \(C\) p and compensation capacitor \(C\) a , where:

[0010] The DC source is connected to the input side of the inverter - filter circuit; compensation capacitor \(C\) p , the first unipolar coil, and the second unipolar coil are connected in series to form branch 1, and the second bipolar coil and compensation capacitor \(C\) a are connected in series to form branch 2. Branch 1 and branch 2 are connected in parallel, where compensation capacitor \(C\) p is connected to the second bipolar coil, and compensation capacitor \(C\) a is connected to the second unipolar coil; the first bipolar coil is connected to the connection point of compensation capacitor \(C\) p and the second bipolar coil, and the other end of the first bipolar coil and the connection point of compensation capacitor \(C\) a and the second unipolar coil are connected to the output side of the inverter - filter circuit.

[0011] Further, the receiving side includes a receiving coil, a secondary compensation capacitor \(C\) s , a rectifier - filter circuit, a variable load, and a second ferrite, where:

[0012] The receiving coil is placed under the second ferrite; the receiving coil is connected in series with the secondary compensation capacitor C s ; the other end of the secondary compensation capacitor C s is connected to the input side of the rectifying and filtering circuit; the output side of the rectifying and filtering 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 a parameter of 0.1 mm * 200 strands; the first ferrite and the second ferrite are made of ferrite material with the model of TDK-PC95 and the material of Mn-Zn.

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

[0015] 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, the intermediate interval sl between the two small rectangular coils in the bipolar coil, and the interval g between the first unipolar coil and the second unipolar coil;

[0016] Step 2: Obtain the fluctuation curve of the sum of the mutual inductances of the first and second unipolar coils when the receiving coil moves through simulation, and confirm the maximum compensated mutual inductance value that meets the wireless power transmission system according to the fluctuation curve, thereby selecting the length wl and the 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 sum of the relative mutual inductances M p1,(a+g) +M p2,(a+g) is the smallest, 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, and M p1,0 , M p2,0 are the mutual inductances corresponding to a + g = 0;

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

[0019]

[0020] where i = 1, 2;

[0021] When the above formula 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. Adjust the intermediate interval sl between the two small rectangular coils in the bipolar coil at this time 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, so as to satisfy ;

[0023] Step 5. To avoid the large influence of the errors in the coil manufacturing process on the resonance of the wireless power transmission system, verify whether the sum of the mutual inductances between the two bipolar coils and the receiving coil exceeds the error range allowed by the wireless power transmission system:

[0024]

[0025] wherein, 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 between the two bipolar coils and the receiving coil;

[0026] If not satisfied, it is necessary to return to Step 1 to re-determine the parameters and perform coil design;

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

[0028]

[0029] wherein, 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 parameters of the bipolar coil should satisfy the following formula:

[0031]

[0032] wherein, 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 satisfied, return to Step 2 to re-select the length wl and the number of turns of the two small rectangular coils in the bipolar coil;

[0034] Step 7. Build a wireless power transmission system according to the single and double pole interleaved stacked coils designed in Steps 1 to 6.

[0035] Compared with the prior art, the remarkable advantages of the present invention are:

[0036] (1) The wireless power transfer system based on single - and dual - polarity interleaved stacked coils has a simple topological structure and strong scalability, and can meet the requirements in different application scenarios.

[0037] (2) The wireless power transfer system based on single - and dual - polarity interleaved stacked coils uses the method of multiplexing single - polarity coils and dual - polarity coils, improving the utilization rate of the coils.

[0038] (3) The wireless power transfer system based on single - and dual - polarity interleaved stacked coils combines dual - polarity coils with rectangular coils for single - polarity coils, improving the compactness of the overall coil structure.

[0039] (4) For the wireless power transfer system based on single - and dual - polarity interleaved stacked coils, when the receiving coil moves laterally, the equivalent mutual inductance and its volatility of the proposed coupling mechanism change less, proving its strong anti - offset ability in the lateral direction.

[0040] (5) For the wireless power transfer system based on single - and dual - polarity interleaved stacked coils, when the length of the receiving coil changes, the equivalent mutual inductance and its volatility of the proposed coupling mechanism change less, having good compatibility with the change in the length of the receiving coil. Therefore, it can effectively avoid the mutual inductance fluctuation caused by the coil length error in the actual manufacturing process.

[0041] (6) The wireless power transfer system based on single - and dual - polarity interleaved stacked coils can ensure constant current in the single - polarity coil, as well as ideal zero - power consumption absorption and constant output voltage characteristics for the proposed single - and dual - polarity interleaved stacked coil structure.

[0042] (7) For the wireless power transfer system based on single - and dual - polarity interleaved stacked coils, even in the case where the proposed single - and dual - polarity interleaved stacked coil structure is most affected by mutual inductance deviation, the input impedance angle of the system can still remain at a small value, achieving ideal ZVS.

[0043] (8) The proposed wireless power transfer system based on single - and dual - polarity interleaved stacked coils has a good suppression effect on the input harmonics generated by load changes during the charging process. Description of the Drawings

[0044] Figure 1 It is a three - dimensional structure diagram of the single - and dual - polarity interleaved stacked coils and the receiving coil of the present invention;

[0045] Figure 2 It is an equivalent circuit diagram of the wireless power transfer system based on single - and dual - polarity interleaved stacked coils of the present invention;

[0046] Figure 3 It is the fundamental - wave decoupled equivalent circuit of the wireless power transfer system of the present invention;

[0047] Figure 4This is the flowchart of the design method of the present invention;

[0048] Figure 5 This is the graph of the equivalent mutual inductance change of the coupling mechanism of the wireless power transfer system when the receiving coil moves horizontally in the present invention;

[0049] Figure 6 This is the graph of the equivalent mutual inductance volatility change of the coupling mechanism of the wireless power transfer system when the receiving coil moves horizontally in the present invention;

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

[0051] Figure 8 This is the experimental and simulation result graph of the received voltage on the secondary side when the receiving coil moves horizontally in the present invention;

[0052] Figure 9 This is for the load resistance R L = 10Ω, the experimental graph of the output voltage and current measurement of the full - bridge inverter;

[0053] Figure 10 This is for the load resistance R L = 2Ω, the experimental graph of the output voltage and current measurement of the full - bridge inverter;

[0054] Figure 11 This is for the load resistance R L = 5Ω, the experimental graph of the output voltage and current measurement of the full - bridge inverter. Specific embodiments

[0055] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings of the specification. 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.

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

[0057] Figure 13D structure diagram of single - and double - pole interleaved stacked coil and receiving coil, where 1 is the first unipolar coil; 2 is the second unipolar coil; 3 is the first bipolar coil; 4 is the second bipolar coil; 5 is the receiving rectangular coil; 6 is the first ferrite; 7 is the second ferrite.

[0058] The proposed single - and double - pole interleaved stacked coil includes the first unipolar coil, the second unipolar coil, the first bipolar coil, and the second bipolar coil; the lengths of the first unipolar coil and the second unipolar coil are a, and the widths are 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 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] As Figure 1 shown, the first unipolar coil is placed at the separation middle of the first bipolar coil with the width centers aligned; the second unipolar coil is placed at the same position of the second bipolar coil; the right - hand small rectangular coil of the first bipolar coil and the left - hand small rectangular coil of the second bipolar coil are stacked and overlapped. At this time, the interval between the first unipolar coil and the second unipolar coil is g; the single - and double - pole interleaved stacked coil is 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 a parameter of 0.1mm * 200 strands; the first ferrite is made of ferrite material with the model of TDK - PC95 and the material of Mn - Zn.

[0061] The transmitting side also includes a DC source, an inverter - filter circuit, and compensation capacitors C p 、C a , the series connection of the compensation capacitor C p , the first unipolar coil, and the second unipolar coil is in parallel with the structure formed by the series connection of the second bipolar coil and the compensation capacitor C a , and then is 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 a receiving coil, a secondary compensation capacitor C s , a rectifier - filter circuit, and a variable load. The length of the receiving coil is c, the width is d, and it is placed on the lower side of the second ferrite; the receiving coil is in series with the secondary compensation capacitor C s ; the secondary compensation capacitor C s is connected to the input side of the rectifier - filter circuit; the output side of the rectifier - filter circuit is connected to the variable load.

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

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

[0065] As Figure 2 shown, L 1 , L 2 are the equivalent inductances of the first bipolar coil and the second bipolar coil respectively, L p1 , L p2 are the equivalent inductances of the first unipolar coil and the second unipolar coil respectively, L s is the equivalent inductance of the receiving coil; C p , C s are the compensation capacitors at the unipolar coil and the receiving coil respectively, C a is the compensation capacitor on the branch of L 2 ; U DC , C d1 are the DC input voltage and the input-side filter capacitor respectively, R L , U out , C d2 are the variable load resistance, voltage and the output-side filter capacitor respectively; Q 1 , Q 2 , Q 3 , Q 4 are the switching transistors in the inverter filter circuit; D 1 , D 2 , D 3 , D 4 are the diodes in the rectifier filter circuit; M a1 , M a2 , M p1 , M p2 are the mutual inductances between L 1 , L 2 , L p1 , L p2 and L s respectively; M 12 is the mutual inductance between L 1 and L 2 ; M p12 is the mutual inductance between L p1 and L p2 ; M a1p2 is the mutual inductance between L 1 and L p2 ; M a2p1 is the mutual inductance between L 2 and L p1 respectively.

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

[0067]

[0068]

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

[0070]

[0071] Ignoring the height difference caused by the overlap between the unipolar coil and the bipolar coil, then at this time, the magnitudes of M a1p2 , M a2p1 are equal. Therefore, it can be known that L 1e , L 2e are equal at this time. And M 12 , M p1p2 are not affected by external factors such as the offset of the receiving coil, the change of load parameters, and the switching of the unipolar coil. Therefore, L 1e , L 2e and L pe can be regarded as the equivalent inductances of L 1 , L 2 and L p1 +L p2 respectively. Applying the KCL and KVL laws to the fundamental wave decoupling equivalent circuit in Figure 3 results in the following formula:

[0072]

[0073] In the formula, U in is the effective value of the fundamental wave voltage output by the full-bridge inverter, ω is the frequency of the wireless power transmission system, and I inis the effective value of the fundamental current output by the full-bridge inverter, I p 、I s are the effective values of the fundamental currents of the unipolar coil and the receiving coil respectively, I 2 is the effective value of the fundamental current on the parallel branch of the primary side L 2 Let the values of the compensation capacitors C 2 、C p 、C s satisfy the following conditions:

[0074]

[0075] According to the conditions of the above formula, the input impedance Z in and the voltage gain ratio G uu of wireless power transfer at this time can be obtained, and their expressions are as follows:

[0076]

[0077]

[0078] where U o is the fundamental effective value of the input voltage of the full-bridge rectifier. In order to make the structure proposed in the present invention satisfy the resonance condition of the wireless power transfer system and maintain the characteristic of constant current in the unipolar coil, two additional compensation mutual inductances M a1 、M a2 are designed to satisfy the following conditions:

[0079]

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

[0081]

[0082]

[0083]

[0084]

[0085] According to the above formulas, it can be seen that the present invention can ensure constant current in the unipolar coil and ideal ZPA and constant output voltage characteristics.

[0086] L1 , L 2 and the additional mutual inductance M added by the receiving coil a1 , M a2 together provide an additional energy transfer channel for wireless power transfer, compensating for the problem of fluctuations in M caused by changes in the position of the receiving coil, and equivalently increasing the mutual inductance value of wireless power transfer. Therefore, when the receiving coil is offset, the relative stability of the equivalent mutual inductance of the system is maintained by the increase in the additional mutual inductance M a , and the problem of degradation in transmission performance caused by the offset at this time can be offset.

[0087] For the system in practical applications, due to manufacturing errors and construction errors, etc., it may not always be possible to ensure that M a1 +M a2 =0 holds. The following analyzes the robustness of the structure proposed in the present invention in the face of deviations in M a1 , M a2 in practical applications, that is, analyzes the influence of the deviations of M a1 , M a2 on the resonance state and output voltage of the proposed wireless power transfer, and uses the input impedance angle θ and the voltage gain ratio G uu to describe the resonance state and output voltage of the system at this time as follows:

[0088]

[0089] where , G uu_ero are respectively the input impedance angle and voltage gain ratio corresponding to the wireless power transfer system when the deviations of M a1 , M a2 are not equal; G uu * represents the per-unit value of the voltage gain ratio from the ideal value due to the deviation; k is the deviation coefficient of the system at this time.

[0090] From the above formula, it can be obtained that the deviations of M a1 , M a2 from the ideal set value, that is, when |M a1 +M a2 |≠0, is not equal to 0 and is less than 1. When the parameters of the wireless power transfer system are determined, k is only related to M - M a2 , |M a1 +M a2 | and the change of R eq during the charging process.

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

[0092]

[0093] In order to make the wireless power transfer system operate under ideal ZVS conditions, the input impedance angle should be maintained between (0, ), and the a1 , a2 deviation should satisfy: Satisfy:

[0094]

[0095] Where , are respectively the a1 , a2 maximum and minimum values that may occur due to the inequality of . Combining the previous formula, it can be seen that , satisfy:

[0096]

[0097] Considering the maximum possible error, the range of values of a1 + a2 for the wireless power transfer system to maintain ideal ZVS conditions 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 characteristic of the wireless power transfer system, given , where is the threshold, so there can be:

[0101]

[0102] In summary, it can be determined that the maximum allowable range of deviation of a1 + a2 while maintaining ideal ZVS and constant output characteristics is:

[0103]

[0104] Where M ero is the maximum value of a1 + a2 ; L f is the equivalent inductance value of the compensation inductor.

[0105] The is 7°, δ is 0.995. Build a simulink simulation model, take the load resistance as 10Ω, M a2 The maximum value M a2max = -1.2 M a1 , and the simulation waveform diagrams of the output voltage and current of the full-bridge inverter are as Figure 7 shown. From Figure 7 it can be obtained 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 7° of the set target, and ideal ZVS can be achieved.

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

[0107] 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, the interval sl between the two small rectangular coils in the bipolar coil, and the interval g between the first unipolar coil and the second unipolar coil;

[0108] Step 2: Obtain the fluctuation curve of the sum of the mutual inductances of the first and second unipolar coils when the receiving coil moves through simulation, and confirm the maximum compensated mutual inductance value that meets the wireless power transmission system according to the fluctuation curve, and thus select the length wl and the 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 sum of the relative mutual inductances M p1,(a+g) +M p2,(a+g) is the smallest, 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] Judge whether the maximum value M ai,max of the mutual inductance between the first and second bipolar coils and the receiving coil satisfies:

[0111]

[0112] where i=1,2;

[0113] When the above formula is not satisfied, return to Step 1 and adjust the parameters of the unipolar coil, the receiving coil, and the distance g between the first unipolar coil and the second unipolar coil;

[0114] Step 4. According to the distance 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 distance sl between the two small rectangular coils in the bipolar coil at this time to satisfy ;

[0115] Step 5. To avoid the large influence of the errors in the coil manufacturing process on the resonance of the wireless power transmission system, verify whether the sum of the mutual inductances between the two bipolar coils and the receiving coil exceeds the error range allowed by the wireless power transmission system:

[0116]

[0117] where 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 between the two bipolar coils and the receiving coil;

[0118] If not satisfied, it is necessary to return to Step 1 to re-determine the parameters and perform coil design;

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

[0120]

[0121] where 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 parameters of the bipolar coil should satisfy the following formula:

[0123]

[0124] where 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 satisfied, return to Step 2 and re-select the length wl and the number of turns of the small rectangular coil in the bipolar coil;

[0126] Step 7. Build a wireless power transmission system according to the single and double pole interleaved stacked coils designed in Steps 1 to 6.

[0127] Embodiment

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

[0129] The values of the experimental parameters are shown in Table 1.

[0130] Table 1 Values of System Experimental Parameters

[0131] parameter value Length a of unipolar coil 150 mm Width b of unipolar coil 100 mm Length c of receiving coil 100 mm Width d of receiving coil 150 mm Width e of small rectangular coil in bipolar coil 100 mm Length wl of small rectangular coil in bipolar coil 100 mm Spacing sl between two small rectangular coils in bipolar coil 135 mm Transmission spacing h between transmitting side and receiving side 100 mm Spacing g between the first unipolar coil and the second unipolar coil 75 mm Wire diameter of the first unipolar coil, the second unipolar coil, the first bipolar coil, the second bipolar coil and the receiving coil 2 mm Number of turns of unipolar coil 5 Number of turns of small rectangular coil in bipolar coil 4 Number of turns of receiving coil 7 Frequency ω of wireless power transfer system 85 kHz Self-inductance of unipolar coil 31.4 μH Self-inductance of receiving coil 56 μH Self-inductance of bipolar coil 17.2 μH <![CDATA[Compensation capacitor C p > 74.8 nF <![CDATA[Compensation capacitor C a > 144.3 nF <![CDATA[Secondary compensation capacitor C s > 68.5 nF

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

[0133] From Figure 5 and Figure 6 it can be seen that for a determined distance g between the first unipolar coil and the second unipolar coil, even if the length of the receiving coil changes at this time, the change in the value of the equivalent mutual inductance and its volatility is very small. The equivalent mutual inductance of the proposed coupling mechanism can remain stable when the position of the receiving coil changes laterally, and the volatility does not exceed 5%. Therefore, the equivalent structure of the transmitting side coil of the proposed coupling mechanism has good compatibility with the change in the length of the receiving coil.

[0134] Through experiments, the feasibility and advancement of the present invention were verified. Figure 8 This is the experimental and simulation result diagram of the secondary side receiving voltage when the receiving coil of the present invention moves laterally. From Figure 8 it can be seen that the experimental and simulation results are close, and the wireless power transfer system proposed by the present invention has good anti-offset characteristics.

[0135] When the load resistance changes, the measurement results of the output voltage and current of the full-bridge inverter are as Figure 9 、 Figure 10 and Figure 11 shown. The resonant state of the proposed wireless power transfer system is basically not affected by the change in the load resistance.

[0136] Generally speaking, the present invention proposes a wireless power transfer system based on single and double-pole interleaved stacked coils, and corresponding design methods are proposed according to this system. This wireless power transfer system has strong anti-lateral offset ability, and can ensure that the system realizes zero-voltage switching and is not affected by load changes.

[0137] It should be noted that although the above description provides an ideal embodiment, it does not limit the scope of protection of the present invention. Under the guiding ideology of the present invention, those skilled in the art can 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 shall be determined strictly 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 bipolar interleaved stacked coil and a first ferrite placed on the lower side of the single bipolar interleaved stacked coil, wherein the single bipolar interleaved stacked coil places two bipolar coils stacked end to end in the gap between two series-connected monopolar coils, specifically: The monopolar and bipolar interleaved stacked coils include 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, the two small rectangular coils of the second bipolar coil are located on both sides of the second unipolar coil, and the two small rectangular coils in the gap between the first unipolar coil and the second unipolar coil are completely overlapped; 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 double-pole 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 double-pole 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 double-pole interleaved stacked coils according to claim 3 is 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 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-pole interleaved stacked coils according to claim 4, characterized in that: The receiving side includes a receiving coil, a secondary compensation capacitor C s , a rectifier and filter circuit, a variable load and a second ferrite, wherein: The receiving coil is placed under 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 rectifying and filtering circuit; the output side of the rectifying and filtering circuit is connected to the variable load.

6. The wireless power transmission system based on single- and double-pole 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-pole and double-pole interleaved stacked coils according to claim 6, characterized in that: The design process is as follows: Step 1, initializing parameters according to the actual space requirements of the wireless power transmission system, including: length a and width b of the unipolar coil, length c and width d of the receiving coil, width e of the small rectangular coil in the bipolar coil, transmission spacing h between the transmitting side and the receiving side, spacing sl between the two small rectangular coils in the bipolar coil, spacing g between the first unipolar coil and the second unipolar coil; 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 satisfies the wireless power transmission system according to the fluctuation curve, and select the length wl and number of turns of the small rectangular coil in the bipolar coil; 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 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; 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; When the above formula is not satisfied, return to step 1 to 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 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 ; Step 5: In order to prevent the error in the coil manufacturing process from 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: ； 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 M is the maximum value of the equivalent mutual inductance of the coupling mechanism of the wireless power transmission system; 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 wl and number of turns of the small rectangular coil in the bipolar coil; Step 7: Build a wireless power transmission system based on the single-pole and bipolar interleaved stacked coils designed in steps 1 to 6.

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