Anti-offset unmanned aerial vehicle wireless charging system and parameter design method thereof

Abstract

The invention provides an anti-offset unmanned aerial vehicle wireless charging system and a parameter design method thereof, which are used for solving the technical problem of low charging efficiency caused by transverse and rotary offset of a coupling mechanism of an existing unmanned aerial vehicle wireless charging system. The system comprises a transmitting end and a receiving end, and is characterized in that the transmitting end comprises a transmitting coil, the transmitting coil comprises an inner side transmitting sub-coil and an outer side transmitting sub-coil which are coaxially arranged, and the inner side transmitting sub-coil is arranged on the inner side of the outer side transmitting sub-coil; the receiving end comprises a receiving coil and a secondary compensation circuit, the secondary compensation circuit comprises a secondary compensation coil, and the secondary compensation coil is attached to the end face of one side of the receiving coil. According to the invention, the magnetic coupling mechanism and the LCC-LCC compensation network are integrated together, and the dislocation tolerance and reliability of the wireless charging system of the unmanned aerial vehicle are enhanced through the parameter design of the turn spacing and the number of turns of the transmitting coil. And the zero-voltage switching effect is obtained through parameter design of the receiving coil and the secondary compensation coil.

Description

Technical Field

[0001] The present invention relates to the field of wireless power transmission, and in particular to an anti-drift wireless charging system for unmanned aerial vehicles and a parameter design method thereof. Background Art

[0002] As a new type of navigation equipment, drones have been widely used in power inspection, military patrol, aerial photography, logistics distribution and other fields. Its flexibility and lightness have enabled its application areas to continue to expand, but at the same time, the limitation of its endurance has gradually become prominent, which has greatly limited its scope and scenarios of use. The traditional charging method for drones is contact charging or battery replacement, but this obviously does not meet the requirements for unmanned and intelligent unmanned systems. At the same time, traditional contact charging also faces many problems such as poor environmental adaptability and plug wear.

[0003] In order to solve this pain point, wireless power transmission (WPT) provides us with a feasible solution. One or more wireless charging platforms are configured in the drone application route. This method greatly compensates for the cruising distance problem caused by the insufficient endurance of the drone, and also realizes unmanned and intelligent operation. However, this solution also faces another problem. Especially under extreme weather and environmental conditions, the parking of the drone on the charging platform is prone to misalignment, resulting in low charging efficiency and unstable power transmission. Most of the existing drone wireless power transmission coupling mechanisms do not have anti-drift capability. Although the mechanical centering structure of some drones can achieve precise alignment of the drone, it greatly increases the complexity of the system. Therefore, it is very necessary to enhance the lateral and rotational offset tolerance of the coupling mechanism suitable for drones. The structures that have made breakthroughs in recent years cannot face the dual challenges of rotation and horizontal offset at the same time. Summary of the invention

[0004] The purpose of the present invention is to provide an anti-drift UAV wireless charging system and a parameter design method thereof, so as to solve the technical problem of low charging efficiency caused by lateral and rotational deviation of the coupling mechanism of the existing UAV wireless charging system.

[0005] An anti-drift UAV wireless charging system comprises a transmitting end and a receiving end, wherein the transmitting end comprises a transmitting coil, wherein the transmitting coil comprises an inner transmitting sub-coil and an outer transmitting sub-coil which are coaxially arranged, and the inner transmitting sub-coil is arranged inside the outer transmitting sub-coil;

[0006] The receiving end comprises a receiving coil and a secondary side compensation circuit. The secondary side compensation circuit comprises a secondary side compensation coil. The secondary side compensation coil is attached to one side end surface of the receiving coil.

[0007] Optionally, the receiving coil includes a first receiving sub-coil and a second receiving sub-coil connected in series, and the secondary compensation coil includes a first compensation sub-coil and a second compensation sub-coil connected in series;

[0008] The first compensation sub-coil is attached to one side end surface of the first receiving sub-coil, the second compensation sub-coil is attached to one side end surface of the second receiving sub-coil, and the first receiving sub-coil and the second receiving sub-coil are respectively installed on the landing gear at the bottom of the drone.

[0009] Optionally, the first receiving sub-coil, the second receiving sub-coil, the first compensation sub-coil and the second compensation sub-coil are all arranged perpendicular to the inner transmitting sub-coil and the outer transmitting sub-coil.

[0010] Optionally, the inner transmitting sub-coil and the outer transmitting sub-coil are both planar annular coils;

[0011] The first receiving sub-coil, the second receiving sub-coil, the first compensation sub-coil and the second compensation sub-coil are all planar double-sided rectangular coils.

[0012] Optionally, the transmitting end further includes a DC power supply, an inverter circuit and a primary compensation circuit connected in sequence, and the output end of the primary compensation circuit is connected to the transmitting coil;

[0013] The receiving end also includes a rectifier filter circuit and a load, the two ends of the receiving coil are connected to the input end of the secondary side compensation circuit, the output end of the secondary side compensation circuit is connected to the input end of the rectifier filter circuit, and the output end of the rectifier filter circuit is connected to the load.

[0014] Optionally, the primary side compensation circuit and the secondary side compensation circuit are symmetrically arranged in an LCC topology structure.

[0015] A parameter design method for an anti-drift UAV wireless charging system is used to design the parameters of the anti-drift UAV wireless charging system, and the specific steps are:

[0016] S1 sets the fixed parameters of the system: given the circuit parameters and output expectations at the initial moment of the system and the allowable deviation range of the output parameters, calculate the maximum allowable number of turns of the coil;

[0017] S2 designs the parameters of the transmitting and receiving coils: sets the variable parameters of the transmitting and receiving coils at the initial moment, and outputs the parameters of the transmitting and receiving coils according to the limiting conditions of the mutual inductance value of the transmitting and receiving coils and the limiting conditions of the number of turns of the transmitting and receiving coils;

[0018] S3 designs the secondary compensation coil parameters: sets the variable parameters of the secondary compensation coil at the initial moment, and outputs the secondary compensation coil parameters according to the mutual inductance limit conditions between the secondary compensation coil and the transmitting coil, the output current limit conditions, and the allowable current limit conditions of the cable.

[0019] Optionally, the specific steps of setting the system initial parameters in step S1 are:

[0020] S1.1 Given the circuit parameters and output expectations of the system at the initial moment, the system initial parameters include the DC power supply value, system frequency, load resistance, outer diameter of the transmitting coil and length of the receiving coil. The output expectations include the expected output current and expected output voltage.

[0021] S1.2 Select the wire diameter of the transmitting coil and the receiving coil, and calculate the maximum number of turns allowed for the transmitting coil and the receiving coil according to the outer diameter of the transmitting coil and the length of the receiving coil;

[0022] S1.3 sets the allowable deviation range of the output parameters, including the allowable deviation range of the mutual inductance of the transmitting coil and the receiving coil and the output current.

[0023] Optionally, the specific steps of designing the parameters of the transmitting and receiving coils in step S2 are:

[0024] S2.1 sets the variable parameters of the transmitting coil and the receiving coil at the initial moment, including the coil turn values ​​of the inner transmitting sub-coil, the outer transmitting sub-coil and the receiving coil, the turn spacing value of the inner transmitting sub-coil and the outer transmitting sub-coil, and the outer diameter value of the outer transmitting sub-coil;

[0025] S2.2 determines whether the mutual inductance value of the first receiving sub-coil and the transmitting coil changes linearly when offset along the y-axis. If so, go to step S2.3. If not, change the variable parameters of the transmitting coil and the receiving coil, and return to step S2.1.

[0026] S2.3 determines whether the mutual inductance of the receiving coil and the transmitting coil is less than the allowable offset range. If so, go to step S2.4. If not, change the variable parameters of the transmitting coil and the receiving coil, and return to step S2.1.

[0027] S2.4 determines whether the number of turns of the transmitting coil and the receiving coil is less than the maximum number of turns allowed. If so, return to step S1 and change the system fixed parameters. If not, go to step S3.

[0028] Optionally, the specific steps of designing the parameters of the secondary compensation coil in step S3 are:

[0029] S3.1 selects the wire diameter of the secondary compensation coil and sets the variable parameters of the secondary compensation coil at the initial moment. The variable parameter values ​​of the secondary compensation coil include the number of turns and the turn spacing value of the secondary compensation coil;

[0030] S3.2 calculates the output current of the system, and simulates the mutual inductance between the secondary compensation coil and the transmitting coil, as well as the self-inductance of the secondary compensation coil;

[0031] S3.3 determines whether the mutual inductance between the secondary compensation coil and the transmitting coil is greater than the self-inductance of the secondary compensation coil, and whether the product of the absolute value of the difference between the output current and the expected output current and the input current of the receiving end is less than a preset threshold value. If so, go to step S3.4; if not, change the variable parameters of the secondary compensation coil and return to step S3.2;

[0032] S3.4 Calculate the system transmitter output current and receiver input current;

[0033] S3.5 determines whether the selected cable diameter allows the current of this magnitude to pass through. If so, output the system parameters. If not, reselect the wire diameters of the transmitting coil and the receiving coil and go to step S1.2.

[0034] Due to the adoption of the above technical solution, the present invention has the following advantages:

[0035] This application integrates the magnetic coupling mechanism with the LCC-LCC compensation network, and the receiving coil and the secondary compensation coil are embedded in the drone landing gear using rectangular planar coils. The misalignment tolerance and reliability of the drone wireless charging system are enhanced by the parameter design of the turn spacing and number of turns of the transmitting coil. The effect of zero voltage switching is obtained by the parameter design of the receiving coil and the secondary compensation coil.

[0036] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings of the present invention are as follows.

[0038] Figure 1 This is a positional relationship diagram of the transmitting coil, receiving coil and secondary compensation coil of the present invention.

[0039] Figure 2 It is a top view of the inner transmitting sub-coil and the outer transmitting sub-coil of the present invention.

[0040] Figure 3 It is a top view of the first receiving sub-coil and the first compensating sub-coil of the present invention.

[0041] Figure 4It is a cross-sectional view of the transmitting coil, receiving coil and secondary compensation coil of the present invention.

[0042] Figure 5 This is an equivalent circuit diagram of the wireless charging system for the drone of the present invention.

[0043] Figure 6 The figure is a flow chart of the parameter design method of the present invention.

[0044] Figure 7 This is a mutual inductance fluctuation diagram when the transmitting end and the receiving end are misaligned.

[0045] Figure 8 This is a dynamic response diagram of the present invention under load switching.

[0046] Fig. 9 This is a diagram of output current and transmission efficiency when the transmitting end and the receiving end are offset according to the present invention.

[0047] In the figure: 1-inner transmitting sub-coil; 2-outer transmitting sub-coil; 3-first receiving sub-coil; 4-second receiving sub-coil; 5-first compensating sub-coil; 6-second compensating sub-coil; 7-magnetic core. DETAILED DESCRIPTION

[0048] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0049] Embodiment 1:

[0050] like Figure 1 The anti-deviating wireless charging system for unmanned aerial vehicles shown in the figure comprises a transmitting end and a receiving end, wherein the transmitting end comprises a transmitting coil, and the transmitting coil comprises an inner transmitting sub-coil 1 and an outer transmitting sub-coil 2 which are coaxially arranged, and the inner transmitting sub-coil 1 is arranged inside the outer transmitting sub-coil 2;

[0051] The receiving end comprises a receiving coil and a secondary side compensation circuit. The secondary side compensation circuit comprises a secondary side compensation coil. The secondary side compensation coil is attached to one side end surface of the receiving coil.

[0052] In this embodiment, the transmitting coil, the receiving coil and the secondary compensation circuit are all wound with Litz wire, and the inner transmitting sub-coil 1 and the outer transmitting sub-coil 2 are connected in series to form the following Figure 3 The transmitting coil L shown in P , transmitting coil L P A magnetic core 7 is arranged below. In the present application, the secondary compensation coil is attached to one side of the receiving coil to integrate the magnetic coupling mechanism with the LCC-LCC compensation network.

[0053] like Figure 1 and Figure 4As shown, the receiving coil includes a first receiving sub-coil 3 and a second receiving sub-coil 4 connected in series, and the secondary compensation coil includes a first compensation sub-coil 5 and a second compensation sub-coil 6 connected in series;

[0054] The first compensation sub-coil 5 is attached to one side end surface of the first receiving sub-coil 3, and the second compensation sub-coil 6 is attached to one side end surface of the second receiving sub-coil 4. The first receiving sub-coil 3 and the second receiving sub-coil 4 are respectively installed on the landing gear at the bottom of the drone.

[0055] In this embodiment, the first receiving sub-coil 3 and the second receiving sub-coil 4 are connected in series to form the following Figure 3 The receiving coil L shown in S The first compensation sub-coil 5 and the second compensation sub-coil 6 are connected in series to form Figure 3 The secondary compensation coil L shown in f2 , transmitting coil L P With receiving coil L S The mutual inductance value of the transmitting coil is M1, P With the secondary compensation coil L f2 The mutual inductance value of the receiving coil is M2, and the receiving coil L S With the secondary compensation coil L f2 The mutual inductance value is M3.

[0056] like Figure 1 and Figure 4 As shown, the first receiving sub-coil 3 , the second receiving sub-coil 4 , the first compensation sub-coil 5 and the second compensation sub-coil 6 are all arranged perpendicular to the inner transmitting sub-coil 1 and the outer transmitting sub-coil 2 .

[0057] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, the inner transmitting sub-coil 1 and the outer transmitting sub-coil 2 are both planar toroidal coils;

[0058] The first receiving sub-coil 3 , the second receiving sub-coil 4 , the first compensation sub-coil 5 and the second compensation sub-coil 6 are all planar double-sided rectangular coils.

[0059] In this embodiment, the transmitting coil L P The parameter design of the turn spacing and number of turns enhances the misalignment tolerance and reliability of the UAV wireless charging system. S With the secondary compensation coil L f2 The parameters are designed to obtain the effect of zero voltage switching.

[0060] like Figure 5As shown, the transmitting end also includes a DC power supply, an inverter circuit and a primary compensation circuit connected in sequence, and the output end of the primary compensation circuit is connected to the transmitting coil;

[0061] The receiving end also includes a rectifier filter circuit and a load, the two ends of the receiving coil are connected to the input end of the secondary side compensation circuit, the output end of the secondary side compensation circuit is connected to the input end of the rectifier filter circuit, and the output end of the rectifier filter circuit is connected to the load.

[0062] In this embodiment, the primary compensation circuit and the secondary compensation circuit are symmetrically arranged in an LCC topology structure. Figure 5 As shown, the primary compensation circuit includes a primary compensation inductor L f1 , primary compensation capacitor C f1 And the primary compensation capacitor C P The secondary compensation circuit includes a secondary compensation coil L f2 , secondary compensation capacitor C S And the secondary compensation capacitor C f2 , the DC power supply is U dc , the load is R L The rectifier filter circuit includes four diodes D1-D4 and a filter capacitor C D The inverter circuit includes four switching tubes Q1-Q4.

[0063] For example Figure 5 Analyze the circuit shown, consider the internal resistance of the coil, and write the following equations using Kirchhoff's voltage law:

[0064]

[0065] in And formula (1) satisfies:

[0066]

[0067] Substituting formula (2) into formula (1), we have:

[0068]

[0069] Since the internal resistance is very small, the solution is:

[0070]

[0071] ω=2πf, where f is the operating frequency.

[0072] From I f2 It can be seen from the expression that the load current is only related to M1 and has nothing to do with M2; and other items remain unchanged during offset, that is, M1 is stable and the output current is stable; it has nothing to do with the load size and has a constant current characteristic.

[0073] Compared with the traditional bilateral LCC, the common bilateral LCC topology for:

[0074]

[0075] This topology can achieve higher output current.

[0076] Primary compensation network impedance Substituting and simplifying, we get:

[0077]

[0078] Design M3 is slightly larger than L f2 , then the primary side of the system is weakly inductive.

[0079]

[0080] Substituting equations (8) and (9) into the equation, we can get the output current at the load end:

[0081]

[0082] From the above formula, it can be seen that in this topology, when M1 is stable in the case of misalignment, the output current I L The mutual inductance M3 between the receiving coil and the compensation coil and the inductance L of the compensation coil are regulated by the coupling mechanism design. f2 The value of can realize the ZVS (zero voltage switching) characteristic of the system, and compared with the traditional bilateral LCC topology, this topology can obtain a larger output current.

[0083] Embodiment 2:

[0084] The transmitting coil in this design uses a planar ring coil, and the receiving coil on the drone end is placed on the landing gear. Its mutual inductance is often relatively stable when offset along the x-axis, but its anti-offset effect along the y-axis is not ideal. In order to improve the stable output of the system when offset along the y-axis, the parameters of the coil need to be designed.

[0085] like Figure 6 As shown, a parameter design method for an anti-drift UAV wireless charging system is characterized in that it is used to design the parameters of the anti-drift UAV wireless charging system described in Example 1, and the specific steps are:

[0086] S1 sets the fixed parameters of the system: given the circuit parameters and output expectations at the initial moment of the system and the allowable offset range of the output parameters, calculate the maximum allowable number of turns of the coil; the specific steps are:

[0087] S1.1 Given the circuit parameters and output expectations of the system at the initial moment, the system initial parameter DC power supply value U dc, system frequency f, load resistance R L , transmitting coil L P The outer diameter d2 and the length d3 of the receiving coil, the output expectation includes the expected output current I LE and the expected output voltage U LE ;

[0088] S1.2 Select the transmitting coil L P and receiving coil L S The wire diameters w2 and w3 are based on the transmitting coil L P The outer diameter d2 and the receiving coil L S The length d3 of the transmitting coil L is calculated P and receiving coil L S Maximum number of turns allowed N PMAX and N SMAX ;

[0089] N SMAX = d4 / 2 w3, N PMAX = d2 / 2 w2 (10)

[0090] Where d4 is the width of the transmitting coil;

[0091] In this embodiment, the first receiving sub-coil 3 and the second receiving sub-coil 4 have the same size, the first compensation sub-coil 5 and the second compensation sub-coil 6 have the same size, and the first receiving sub-coil 3, the second receiving sub-coil 4, the first compensation sub-coil 5 and the second compensation sub-coil 6 have the same length and width. S Maximum number of turns allowed N SMAX The maximum number of turns allowed by the first receiving sub-coil 3 and the second receiving sub-coil 4. P Maximum number of turns allowed N PMAX The maximum number of turns allowed for the outer transmitting sub-coil 2. Set the transmitting coil L P The wire diameter w2 is 3.3 mm, and the receiving coil L S and secondary compensation coil L f2 The wire diameter w3 is 2.1mm.

[0092] S1.3 Set the allowable deviation range of output parameters, including the transmitting coil L P and receiving coil L S Mutual inductance and the allowable deviation range of output current.

[0093] In this embodiment, the transmitting coil L is set P and receiving coil L S The allowable offset range of mutual inductance is 10%, and the allowable offset range of output current satisfies:

[0094] I S |I L-I LE |≤2% (11)

[0095] In the formula, I S is the transmitter output current, I L is the output current of the receiving end, I LE is the expected output current of the receiver.

[0096] S2 Design the parameters of the transmitting and receiving coils: Set the transmitting coil L at the initial moment P With receiving coil L S The variable parameters of the transmitting coil L P and receiving coil L S Mutual inductance limit conditions and transmitting coil L P and receiving coil L S The number of turns of the output transmitting coil L is limited P and receiving coil L S Parameters; the specific steps are:

[0097] S2.1 sets the variable parameters of the transmitting coil and receiving coil at the initial moment, including the inner transmitting sub-coil 1, the outer transmitting sub-coil 2 and the receiving coil L S The coil turns value N P1 、N P2 and N S , and the turn spacing value D between the inner transmitting sub-coil 1 and the outer transmitting sub-coil 2 P1 and D P2 , and the outer diameter value d2 of the outer transmitting sub-coil 2;

[0098] In this embodiment, the inner transmitting sub-coil 1, the outer transmitting sub-coil 2 and the receiving coil L are initially set. S The coil turns value N P1 、N P2 and N S Both are 1, the turn spacing value D between the inner transmitting sub-coil 1 and the outer transmitting sub-coil 2 P1 and D P2 is 0, and the outer diameter d2 of the outer transmitting sub-coil 2 is 0.

[0099] S2.2 Determine the first receiving sub-coil 3 and the transmitting coil L P Whether the mutual inductance value changes linearly when it is offset along the y-axis, if so, go to step S2.3, if not, change the variable parameters of the transmitting coil and the receiving coil, and return to step S2.1;

[0100] In this embodiment, the first receiving sub-coil 3 and the transmitting coil L P The mutual inductance value is M 11 , the second receiving sub-coil 4 and the transmitting coil L P The mutual inductance value is M12 , receiving coil L S With the transmitting coil L P The mutual inductance value M1=M 11 +M 12 .

[0101] S2.3 Determine the receiving coil L S With the transmitting coil L P Is the mutual inductance value less than the allowable offset range? If so, go to step S2.4. If not, change the transmitting coil L. P With receiving coil L S The variable parameters are returned to step S2.1;

[0102] In this embodiment, the receiving coil L S With the transmitting coil L P The allowable fluctuation range of mutual inductance value is 10%.

[0103] S2.4 Determine the transmitting coil L P and receiving coil L S Number of turns N P and N S Is it less than the maximum number of turns N allowed? PMAX and N SMAX If yes, then return to step S1 and change the system fixed parameters; if no, then go to step S3.

[0104] S3 Design the secondary compensation coil parameters: Set the secondary compensation coil L at the initial moment f2 The variable parameters are based on the secondary compensation coil L f2 With the transmitting coil L P Mutual inductance limit conditions, output current limit conditions, and cable allowable current limit conditions Output secondary compensation coil L f2 Parameters; the specific steps are:

[0105] S3.1 Select the secondary compensation coil L f2 The wire diameter w4 is set, and the secondary compensation coil L is set at the initial moment. f2 Variable parameters, secondary compensation coil L f2 The variable parameter values ​​include the secondary compensation coil L f2 Number of coil turns N f2 And the turn spacing value D P3 ;

[0106] S3.2 Calculate the output current I of the system L , and simulate the secondary compensation coil L f2 With the transmitting coil L P The mutual inductance value M3 between the two sides, and the secondary compensation coil L f2 The self-inductance value L f2 ;

[0107] S3.3 Determine the secondary compensation coil L f2 With the transmitting coil L P The mutual inductance M3 between them is greater than the secondary compensation coil L f2 The self-inductance value, and the product of the absolute value of the difference between the output current and the expected output current and the input current of the receiving end are less than the preset threshold value. If yes, go to step S3.4. If not, change the secondary compensation coil L f2 The variable parameters are returned to step S3.2;

[0108] S3.4 Calculate the system transmitter output current I P and the receiving input current I S ;

[0109] S3.5 determines whether the selected cable diameter allows the current to pass through. If so, output the system parameters. If not, reselect the transmitting coil L. P and receiving coil L S and go to step S1.2.

[0110] S4 simulation verification: The parameters of the wireless charging system for the unmanned aerial vehicle described in Example 1 are designed by the design method from step S1 to step S3 to obtain the coupling mechanism parameters shown in Table 1.

[0111] Table 1 Coupling mechanism parameters

[0112] parameter value parameter value <![CDATA[d1]]> 400mm <![CDATA[N f2 ]]> 4 <![CDATA[d2]]> 520mm <![CDATA[W1]]> 5mm <![CDATA[d3]]> 260mm <![CDATA[W2]]> 3.3mm <![CDATA[d4]]> 60mm <![CDATA[W3]]> 2.1mm <![CDATA[d5]]> 236mm <![CDATA[W4]]> 2.1mm <![CDATA[N p1 ]]> 14 <![CDATA[d p1 ]]> 2mm <![CDATA[N p2 ]]> 11 <![CDATA[d p2 ]]> 8mm <![CDATA[N s ]]> 11 <![CDATA[d p3 ]]> 0mm

[0113] As shown in Table 1, d1 is the outer diameter of the inner transmitting sub-coil 1, d2 is the outer diameter of the outer transmitting sub-coil 2, d3 is the length of the first receiving sub-coil 3, the second receiving sub-coil 4, the first compensation sub-coil 5 and the second compensation sub-coil 6, d4 is the width of the first receiving sub-coil 3, the second receiving sub-coil 4, the first compensation sub-coil 5 and the second compensation sub-coil 6, d5 is the distance between the first receiving sub-coil 3 and the second receiving sub-coil 4, N p1 is the number of turns of the inner transmitting sub-coil 1, N p2 is the number of turns of the outer transmitting sub-coil 2, N s The receiving coil L S Number of turns, N f2 L is the secondary compensation coil f2 The number of turns, W1 is the thickness of the magnetic core 7, W2 is the transmitting coil L P The thickness of W3 is the receiving coil L S The thickness of W4 is the secondary compensation coil L f2 Thickness, d p1 is the turn spacing of the inner transmitting sub-coil 1, d p2is the turn spacing of the outer transmitting sub-coil 2, d p3 The receiving coil L S and secondary compensation coil L f2 The turn spacing.

[0114] Through the coupling mechanism parameter design, L f2 =13.98μH, M3=18.73μH. From formula (6), we can see that when M3>L f2 The imaginary part of the primary impedance can be made positive, and the imaginary part is much smaller than the real part. The weak inductive primary impedance can realize the zero voltage switching (ZVS) of the primary inverter.

[0115] Through the design of the coupling mechanism parameters, the mutual inductance M between the single-side receiving coil and the transmitting coil when the y-axis lateral offset is generated 11 、M 12 The mutual inductance fluctuation is shown as follows: Figure 7 As shown, Figure 7 (a) is shown. The increase and decrease of the mutual inductance of the two receiving coils cancel each other out, so the system can maintain a relatively stable mutual inductance when it is offset along the y-axis. The mutual inductance fluctuation of the system does not exceed 10% within the range of 7cm offset along the y-axis and 10cm offset along the x-axis. In addition, due to the disc structure of the transmitting coil of the coupling mechanism, the coupling mechanism can achieve basically unchanged mutual inductance under 360° rotation.

[0116] The feasibility of this system design is verified through experiments. Figure 8 It is the dynamic response of voltage and current at the output end and after the inverter when the load end size changes.

[0117] The output current and efficiency of the system are recorded under lateral displacement and rotation. The current and efficiency changes under different displacement degrees are as follows: Fig. 9 The transmission efficiency η of the system can reach 85.6% without offset, and the output current does not fluctuate by more than 10% under the 4.5A benchmark when the output current is offset by 70mm on the y-axis or 100mm on the x-axis.

[0118] In summary, this application integrates the magnetic coupling mechanism with the LCC-LCC compensation network, and the receiving coil and the secondary compensation coil are embedded in the UAV landing gear using rectangular planar coils. A set of parameter optimization methods is proposed for the coupling mechanism, and finally the system can achieve high anti-offset performance of wireless charging of UAVs, and the system has the characteristics of ZVS, relatively large output current, and the output current is independent of the load size.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. An anti-drift UAV wireless charging system, comprising a transmitting end and a receiving end, characterized in that: The transmitting end comprises a transmitting coil, the transmitting coil comprises an inner transmitting sub-coil (1) and an outer transmitting sub-coil (2) which are coaxially arranged, the inner transmitting sub-coil (1) being arranged inside the outer transmitting sub-coil (2); The receiving end comprises a receiving coil and a secondary side compensation circuit. The secondary side compensation circuit comprises a secondary side compensation coil. The secondary side compensation coil is attached to one side end surface of the receiving coil.

2. The anti-drift UAV wireless charging system according to claim 1, characterized in that: The receiving coil comprises a first receiving sub-coil (3) and a second receiving sub-coil (4) connected in series, and the secondary compensation coil comprises a first compensation sub-coil (5) and a second compensation sub-coil (6) connected in series; The first compensation sub-coil (5) is attached to one side end surface of the first receiving sub-coil (3), and the second compensation sub-coil (6) is attached to one side end surface of the second receiving sub-coil (4). The first receiving sub-coil (3) and the second receiving sub-coil (4) are respectively mounted on a landing gear at the bottom of the drone.

3. The anti-drift UAV wireless charging system according to claim 2, characterized in that: The first receiving sub-coil (3), the second receiving sub-coil (4), the first compensation sub-coil (5) and the second compensation sub-coil (6) are all arranged perpendicularly to the inner transmitting sub-coil (1) and the outer transmitting sub-coil (2).

4. The anti-drift UAV wireless charging system according to claim 2, characterized in that: The inner transmitting sub-coil (1) and the outer transmitting sub-coil (2) are both planar annular coils; The first receiving sub-coil (3), the second receiving sub-coil (4), the first compensation sub-coil (5) and the second compensation sub-coil (6) are all planar double-sided rectangular coils.

5. The anti-drift UAV wireless charging system according to claim 1, characterized in that: The transmitting end also includes a DC power supply, an inverter circuit and a primary compensation circuit connected in sequence, and the output end of the primary compensation circuit is connected to the transmitting coil; The receiving end also includes a rectifier filter circuit and a load, the two ends of the receiving coil are connected to the input end of the secondary side compensation circuit, the output end of the secondary side compensation circuit is connected to the input end of the rectifier filter circuit, and the output end of the rectifier filter circuit is connected to the load.

6. The anti-drift wireless charging system for unmanned aerial vehicles according to claim 5, characterized in that: The primary side compensation circuit and the secondary side compensation circuit are symmetrically arranged in an LCC topology structure.

7. A parameter design method for an anti-drift UAV wireless charging system, characterized in that: The method is used to design the parameters of the anti-drift UAV wireless charging system according to any one of claims 1 to 6, and the specific steps are: S1 sets the fixed parameters of the system: given the circuit parameters and output expectations at the initial moment of the system and the allowable deviation range of the output parameters, calculate the maximum allowable number of turns of the coil; S2 designs the parameters of the transmitting and receiving coils: sets the variable parameters of the transmitting and receiving coils at the initial moment, and outputs the parameters of the transmitting and receiving coils according to the limiting conditions of the mutual inductance value of the transmitting and receiving coils and the limiting conditions of the number of turns of the transmitting and receiving coils; S3 designs the secondary compensation coil parameters: sets the variable parameters of the secondary compensation coil at the initial moment, and outputs the secondary compensation coil parameters according to the mutual inductance limit conditions between the secondary compensation coil and the transmitting coil, the output current limit conditions, and the allowable current limit conditions of the cable.

8. The parameter design method of a non-drifting UAV wireless charging system according to claim 7, characterized in that: The specific steps for setting the system initial parameters in step S1 are: S1.1 Given the circuit parameters and output expectations of the system at the initial moment, the system initial parameters include the DC power supply value, system frequency, load resistance, outer diameter of the transmitting coil and length of the receiving coil. The output expectations include the expected output current and expected output voltage. S1.2 Select the wire diameter of the transmitting coil and the receiving coil, and calculate the maximum number of turns allowed for the transmitting coil and the receiving coil according to the outer diameter of the transmitting coil and the length of the receiving coil; S1.3 sets the allowable deviation range of the output parameters, including the allowable deviation range of the mutual inductance of the transmitting coil and the receiving coil and the output current.

9. The parameter design method of a non-drifting UAV wireless charging system according to claim 7, characterized in that: The specific steps for designing the parameters of the transmitting and receiving coils in step S2 are: S2.1 sets variable parameters of the transmitting coil and the receiving coil at the initial moment, including the coil turn values ​​of the inner transmitting sub-coil (1), the outer transmitting sub-coil (2) and the receiving coil, the turn spacing value of the inner transmitting sub-coil (1) and the outer transmitting sub-coil (2), and the outer diameter value of the outer transmitting sub-coil (2); S2.2 determines whether the mutual inductance value of the first receiving sub-coil (3) and the transmitting coil changes linearly when offset along the y-axis. If so, go to step S2.

3. If not, change the variable parameters of the transmitting coil and the receiving coil, and return to step S2.

1. S2.3 determines whether the mutual inductance of the receiving coil and the transmitting coil is less than the allowable offset range. If so, go to step S2.

4. If not, change the variable parameters of the transmitting coil and the receiving coil, and return to step S2.

1. S2.4 determines whether the number of turns of the transmitting coil and the receiving coil is less than the maximum number of turns allowed. If so, return to step S1 and change the system fixed parameters. If not, go to step S3.

10. The parameter design method of a non-drifting UAV wireless charging system according to claim 8, characterized in that: The specific steps of designing the secondary compensation coil parameters in step S3 are: S3.1 selects the wire diameter of the secondary compensation coil and sets the variable parameters of the secondary compensation coil at the initial moment. The variable parameter values ​​of the secondary compensation coil include the number of turns and the turn spacing value of the secondary compensation coil; S3.2 calculates the output current of the system, and simulates the mutual inductance between the secondary compensation coil and the transmitting coil, as well as the self-inductance of the secondary compensation coil; S3.3 determines whether the mutual inductance between the secondary compensation coil and the transmitting coil is greater than the self-inductance of the secondary compensation coil, and whether the product of the absolute value of the difference between the output current and the expected output current and the input current of the receiving end is less than a preset threshold value. If so, go to step S3.4; if not, change the variable parameters of the secondary compensation coil and return to step S3.2; S3.4 Calculate the system transmitter output current and receiver input current; S3.5 determines whether the selected cable diameter allows the current of this magnitude to pass through. If so, output the system parameters. If not, reselect the wire diameters of the transmitting coil and the receiving coil and go to step S1.2.

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