Wide-range decoupling frequency autonomous wireless power transmission system

Abstract

The invention relates to the technical field of wireless power transmission, and particularly discloses a wide-range decoupling frequency autonomous wireless power transmission system, which is characterized in that a direct current source is adopted as a power supply of a transmitting end, and autonomous push-pull circuits with the same circuit structure are adopted as a current inverter and a push-pull rectifier; the system stable autonomous oscillation frequency capable of enabling the system to have the autonomous oscillation stability characteristic is obtained through self-adaptive calculation according to current system parameters (invariable parameters and variable mutual inductance and load) so as to drive switching tubes of a current type inverter and a push-pull rectifier, and therefore system decoupling under the wide-range change of the coupling coefficient and the load is achieved; and high-efficiency power transmission under the wide-range change of the coupling coefficient and the load is realized. An experimental result is consistent with a theoretical result, which proves that the wide-range decoupling frequency autonomous wireless power transmission system provided by the embodiment of the invention realizes high-efficiency power transmission effectiveness through decoupling under the wide-range change of the coupling coefficient and the load.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless power transmission, and in particular to a frequency autonomous wireless power transmission system with wide range decoupling. Background Art

[0002] In recent years, inductive wireless power transfer (WPT) systems have been successfully applied to electric vehicles, drones, mobile wireless charging and other systems. The output characteristics of such systems are closely related to inherent parameters such as coupling coefficient, load, self-inductance and compensation capacitance. However, in practical applications, the inevitable changes in these parameters can lead to system detuning due to the misalignment of the coupling mechanism, environmental factors and load changes. This leads to reduced smoothness of the system output voltage, increased power loss and reduced system stability. In order to ensure stable system output and improve the flexibility of power transmission, the system's tolerance to misalignment errors must be improved.

[0003] Methods to solve parameter deviation and maintain the output stability of WPT system mainly include improving coil structure, optimizing topology design or adding control mechanism to stabilize output, among which optimizing topology design is a more effective way. The introduction of hybrid topology can improve the tolerance of WPT system to misalignment error. However, most existing hybrid compensation topologies are fixed frequency and voltage driven, and large DC side capacitors limit the types of compensation topologies that can be mixed, resulting in poor dynamic performance and adaptability to parameter changes of the system, which cannot meet the requirements of misalignment tolerance and large-scale decoupling in WPT system. Summary of the invention

[0004] The present invention provides a frequency autonomous wireless power transmission system with wide range decoupling, which solves the technical problem that the existing hybrid compensation topologies are all fixed frequency and voltage driven, and cannot meet the requirements of misalignment tolerance and large-scale decoupling in the WPT system.

[0005] In order to solve the above technical problems, the present invention provides a frequency autonomous wireless power transmission system with wide range decoupling, comprising a DC current source U connected in sequence dc , current source inverter, hybrid topology, push-pull rectifier and load resistor R L ; The DC current source U dc The current source inverter is input, and after being transformed by the current source inverter, a square wave current source is output to the hybrid topology; the hybrid topology wirelessly couples energy to the push-pull rectifier; the push-pull rectifier realizes AC to DC conversion, and the load resistor R L power supply; the current source inverter and the push-pull rectifier adopt an autonomous push-pull circuit with the same circuit structure and are symmetrically connected in the system.

[0006] Preferably, the current-type inverter is provided with a transmitting-end switch tube control circuit, and the push-pull rectifier is provided with a receiving-end switch tube control circuit. The transmitting-end switch tube control circuit or the receiving-end switch tube control circuit is used to calculate the system stable autonomous oscillation frequency according to the current parameters of the system. The transmitting-end switch tube control circuit and the receiving-end switch tube control circuit respectively drive the switch tubes in the current-type inverter and the push-pull rectifier with the system stable autonomous oscillation frequency.

[0007] Preferably, the step of calculating the system stable autonomous oscillation frequency according to the current parameters of the system includes:

[0008] Determining a transfer function between an output voltage and an output current of the current source inverter according to a circuit structure of the system;

[0009] Set the phase of the transfer function's phase-frequency characteristic to 0, substitute the current system parameters, and solve for multiple frequencies;

[0010] The system output voltage gain at multiple frequencies is calculated and solved, and the frequency with the maximum system output voltage gain is determined as the system stable autonomous oscillation frequency.

[0011] Preferably, the autonomous push-pull circuit comprises a DC inductor, a phase-divided first inductor, a phase-divided second inductor, a first switch tube, a second switch tube and a switch tube control circuit, wherein one end of the DC inductor is connected to a DC current source U dc or load resistance R L The other end of the DC inductor is connected to the common connection end of the first phase-divided inductor and the second phase-divided inductor, the other end of the first phase-divided inductor is connected to the drain of the first switch tube as the first AC output end or the first AC input end, and the other end of the second phase-divided inductor is connected to the drain of the second switch tube as the second AC output end or the second AC input end. The gate and drain of the first switch tube and the gate and drain of the second switch tube are also connected to the transmitting end switch tube control circuit or the receiving end switch tube control circuit. The transmitting end switch tube control circuit or the receiving end switch tube control circuit is used to calculate the system stable autonomous oscillation frequency according to the current parameters of the system and alternately connect the first switch tube and the second switch tube at the frequency to realize DC to AC or AC to DC.

[0012] Preferably, the hybrid topology adopts a dual-orthogonal DD-type coupling mechanism and a PP-SS compensation topology; the dual-orthogonal DD-type coupling mechanism includes a DD-type transmitting coil and a DD-type receiving coil, wherein the DD-type transmitting coil includes a D-type first transmitting coil L connected in series p1 and the D-type second transmitting coil L p2 , the DD type receiving coil comprises a D type first receiving coil L connected in series s1 and the D-type second receiving coil L s2The PP-SS compensation topology includes a D-type first transmitting coil L p1 Parallel transmitter parallel compensation capacitor C p1 , and the D-type second transmitting coil L p2 The transmitter series compensation capacitor C p2 , and the D-type first receiving coil L s1 The parallel compensation capacitor C of the receiving end s1 , and the D-type second receiving coil L s2 The receiving end series compensation capacitor C s2 The first and second AC output terminals of the current source inverter are respectively connected to the D-type first transmitting coil L p1 One end and the other end of the D-type first transmitting coil L p1 The other end is also connected in series with the D-type second transmitting coil L p2 And the transmitter series compensation capacitor C p2 The first and second AC input ends of the push-pull rectifier are respectively connected to the D-type first receiving coil L s1 One end and the other end of the D-type first receiving coil L s1 The other end is also connected in series with the D-type second receiving coil L s2 And the receiving end series compensation capacitor C s2 Then connected to the first AC input end of the push-pull rectifier.

[0013] Preferably, the step of determining the transfer function between the output voltage and the output current of the current source inverter according to the circuit structure of the system specifically comprises the following steps:

[0014] The system is simplified into a two-port network consisting of an equivalent AC source connected in sequence, a hybrid topology, and an equivalent load resistor R eq , where the equivalent AC source is a DC current source U dc The equivalent load resistance R eq The push-pull rectifier and load resistor R L The whole is equivalent;

[0015] constructing a transfer model of the two-port network according to the two-port network;

[0016] A transfer function between an output voltage and an output current of the current source inverter is obtained according to the transfer model.

[0017] Preferably, the transfer model of the two-port network is expressed as:

[0018]

[0019] Among them, U1(s) and I1(s) represent the output voltage and current of the equivalent AC source related to the complex variable s, and U2(s) and I2(s) represent the equivalent load resistance R eq Input voltage and current, Y 11 (s), Y 12 (s), Y 21 (s), Y 22 (s) is the admittance function,

[0020] Preferably, the transfer function between the output voltage and the output current of the current source inverter is U2(s):I1(s), which is equal to (1+R eq Y 22 (s)):(R eq Y 11 (s)Y 22 (s)+R eq Y 12 (s)Y 21 (s)+Y 11 (s)).

[0021] Preferably, the system output voltage gain at the frequency ω is calculated as A(ω)=|G2(s)|, where G2(s) represents the ratio of U2(s) to I2(s), and || represents the modulus.

[0022] Preferably, the ratio of U2(s) to I2(s) is equal to Y 12 (s)R eq :(Y 22 (s)R eq +1).

[0023] The present invention provides a wide-range decoupled frequency autonomous wireless power transmission system, in which the power supply of the transmitting end adopts a DC current source, the current-type inverter and the push-pull rectifier adopt an autonomous push-pull circuit with the same circuit structure, and the system stable autonomous oscillation frequency that enables the system to have autonomous oscillation stability characteristics is obtained through adaptive calculation of the current system parameters (unchanged parameters and changing mutual inductance and load), so as to drive the switch tubes of the current-type inverter and the push-pull rectifier, thereby realizing system decoupling under wide-range changes in coupling coefficient and load, and realizing high-efficiency power transmission under wide-range changes in coupling coefficient and load. The experimental results are consistent with the theoretical results, which confirms the effectiveness of the wide-range decoupled frequency autonomous wireless power transmission system proposed in the embodiment of the present invention in decoupling under wide-range changes in coupling coefficient and load to achieve high-efficiency power transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a circuit diagram of a frequency autonomous wireless power transmission system with wide range decoupling provided by an embodiment of the present invention;

[0025] Figure 2 It is a diagram of the inherent complete resonant frequency of the system when the coil self-inductance and coupling coefficient change, provided by an embodiment of the present invention;

[0026] Figure 3 The embodiment of the present invention provides Figure 1 Simplified model diagram of ;

[0027] Figure 4 is a transfer model diagram of a system provided by an embodiment of the present invention;

[0028] Figure 5 1 is a polar coordinate diagram of frequency characteristics provided by an embodiment of the present invention, wherein (a) and (b) correspond to ignoring ESR and introducing ESR, respectively;

[0029] Figure 6 is a system gain curve diagram of ignoring ESR and introducing ESR under load change provided by an embodiment of the present invention;

[0030] Figure 7 is an experimental waveform diagram provided by an embodiment of the present invention;

[0031] Figure 8 is a relationship diagram between transmission distance, self-inductance and coupling coefficient provided by an embodiment of the present invention;

[0032] Fig. 9 is a gain diagram of the system at different coupling coefficients and operating frequencies when the load is 100Ω provided by an embodiment of the present invention;

[0033] Fig.10 is a gain diagram of the system at different coupling coefficients and operating frequencies when the load is 50Ω provided by an embodiment of the present invention;

[0034] Fig.11 is an efficiency curve diagram under different loads provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The following specifically illustrates the implementation mode of the present invention in conjunction with the accompanying drawings. The embodiments are provided for illustrative purposes only and cannot be understood as limiting the present invention. The accompanying drawings are provided for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0036] An embodiment of the present invention provides a frequency autonomous wireless power transmission system with wide range decoupling, such as Figure 1 As shown, it includes a DC current source U connected in series dc , current source inverter, hybrid topology, push-pull rectifier and load resistor R L . DC current source Udc The input current source inverter outputs a square wave current source to the hybrid topology after transformation by the current source inverter; the hybrid topology wirelessly couples the energy to the push-pull rectifier; the push-pull rectifier realizes AC to DC conversion, and the load resistor R L powered by.

[0037] Among them, the current-source inverter and the push-pull rectifier use an autonomous push-pull circuit with the same circuit structure. The current-source inverter is used for direct current to alternating current (DC-AC), and the push-pull rectifier is used for alternating current to direct current (AC-DC). They are symmetrically connected in the WPT system. The autonomous push-pull circuit is a soft switching circuit, which is a current-source circuit, including a DC inductor, a first phase-dividing inductor, a second phase-dividing inductor (the first phase-dividing inductor and the second phase-dividing inductor form a phase-dividing inductor for current phase separation), a first switch tube, a second switch tube, and a switch tube control circuit, wherein one end of the DC inductor is connected to a DC current source U dc or load resistance R L The other end of the DC inductor is connected to the common connection end of the first phase-divided inductor and the second phase-divided inductor, the other end of the first phase-divided inductor is connected to the drain of the first switch tube as the first AC output end or the first AC input end, and the other end of the second phase-divided inductor is connected to the drain of the second switch tube as the second AC output end or the second AC input end. The gate and drain of the first switch tube and the gate and drain of the second switch tube are also connected to the transmitting end switch tube control circuit or the receiving end switch tube control circuit. The transmitting end switch tube control circuit or the receiving end switch tube control circuit is used to calculate the system stable autonomous oscillation frequency according to the current parameters of the system and alternately connect the first switch tube and the second switch tube at the frequency to realize DC to AC or AC to DC.

[0038] like Figure 1 As shown, the current source inverter specifically includes a DC inductor L dc1 , Phase first inductor L a , Phase-divided second inductor L b (Phase first inductance L a and the second phase inductor L b The DC inductor L forms a phase-dividing inductor for current phase separation), the first switch tube Q1, the second switch tube Q2 and the transmitter switch tube control circuit, wherein the DC inductor L dc1 One end is connected to a DC current source U dc , DC inductance L dc1 The other end is connected to the first phase inductor L a , Phase-divided second inductor L b The common connection terminal, the first phase inductor L a The other end of the first AC output terminal is connected to the drain of the first switch tube Q1, and the second inductor L bThe other end is connected to the drain of the second switch tube Q2 as the second AC output end. The gate and drain of the first switch tube Q1 and the gate and drain of the second switch tube Q2 are also connected to the transmitter switch tube control circuit. The transmitter switch tube control circuit is used to calculate the system stable autonomous oscillation frequency and alternately connect the first switch tube Q1 and the second switch tube Q2 at this frequency to realize DC to AC conversion. DC power supply U dc and DC inductance L dc1 Together they form a quasi-DC power supply. a and L b The phase-divided inductor is formed, and the switch tubes Q1, Q2 and the phase-divided inductor form a push-pull inverter. The autonomous push-pull circuit uses the natural zero-crossing moment of the power flow to realize the flexible energy conversion process, and can achieve frequency adaptation under stable system conditions. Its basic principle is that when the voltage across the parallel capacitor passes through zero, the switch tubes are alternately turned on. Under steady-state operation, the phase-divided inductor current is approximately constant, and the push-pull inverter can be equivalent to a square wave current source.

[0039] like Figure 1 As shown, the push-pull rectifier specifically includes a DC inductor L dc2 , Phase first inductor L d , Phase-divided second inductor L c (Phase first inductance L d and the second phase inductor L c The DC inductor L forms a phase-dividing inductor for current phase separation), the first switch tube Q4, the second switch tube Q3 and the receiving end switch tube control circuit, wherein the DC inductor L dc2 One end of the load resistor R L , DC inductance L dc2 The other end is connected to the first phase inductor L d , Phase-divided second inductor L c The common connection terminal, the first phase inductor L d The other end of the first AC input terminal is connected to the drain of the first switch tube Q4, and the second inductor L c The other end is connected to the drain of the second switch tube Q3 as the second AC input end, and the gate and drain of the first switch tube Q4 and the gate and drain of the second switch tube Q3 are also connected to the receiving end switch tube control circuit, which is used to calculate the system stable autonomous oscillation frequency and alternately connect the first switch tube Q4 and the second switch tube Q3 at the frequency to realize AC to DC conversion. The push-pull rectifier has the same control principle as the current-type inverter.

[0040] In order to facilitate wide-range decoupling, an embodiment of the present invention provides a wide-range decoupling frequency autonomous wireless power transmission system, such as Figure 1As shown, the hybrid topology adopts a dual-orthogonal DD-type coupling mechanism and a PP-SS compensation topology. The dual-orthogonal DD-type coupling mechanism includes a DD-type transmitting coil and a DD-type receiving coil, wherein the DD-type transmitting coil includes a D-type first transmitting coil L connected in series. p1 and the D-type second transmitting coil L p2 , the DD type receiving coil comprises a D type first receiving coil L connected in series s1 and the D-type second receiving coil L s2 The PP-SS compensation topology includes a D-type first transmitting coil L p1 Parallel transmitter parallel compensation capacitor C p1 (P type), and the D type second transmitting coil L p2 The transmitter series compensation capacitor C p2 (S type), and the D type first receiving coil L s1 The parallel compensation capacitor C of the receiving end s1 (P type), and the D type second receiving coil L s2 The receiving end series compensation capacitor C s2 The first and second AC output terminals of the current source inverter are respectively connected to the D-type first transmitting coil L p1 One end and the other end of the D-type first transmitting coil L p1 The other end is also connected in series with the D-type second transmitting coil L p2 And the transmitter series compensation capacitor C p2 The first and second AC input terminals of the push-pull rectifier are respectively connected to the D-type first receiving coil L s1 One end and the other end of the D-type first receiving coil L s1 The other end is also connected in series with the D-type second receiving coil L s2 And the receiving end series compensation capacitor C s2 After that, it is connected to the first AC input terminal of the push-pull rectifier. Due to the decoupling characteristics of the orthogonal DD type coil, there is only a non-orthogonal D-type first transmitting coil L between the dual orthogonal DD type coupling mechanism. p1 and the D-type first receiving coil L s1 The mutual inductance M1 and the non-orthogonal D-type second transmitting coil L p2 and the D-type second receiving coil L s2 The mutual inductance M2 between them.

[0041] The four energy transmission coils in this example use coils with the same parameters, with self-inductance L p1 =L p2 =L s1 =L s2 .

[0042] Figure 2The system shows seven frequency characteristic curves, representing the inherent complete resonant frequency of the system when the coil self-inductance and coupling coefficient change. Among them, f5 is the stable operating frequency of the system, that is, the stable autonomous oscillation frequency. At this time, the output gain (Gain) of the system remains constant in a wide range. The following analyzes how to determine the stable autonomous oscillation frequency of the system. The general steps include:

[0043] Determining a transfer function between an output voltage and an output current of the current source inverter according to a circuit structure of the system;

[0044] Let the phase of the transfer function's phase-frequency characteristic be 0, substitute the current system parameters, and solve for multiple frequencies;

[0045] The system output voltage gain at multiple frequencies is calculated and solved, and the frequency with the maximum system output voltage gain is determined as the system stable autonomous oscillation frequency.

[0046] Determining the transfer function between the output voltage and the output current of the current source inverter according to the circuit structure of the system specifically includes the following steps:

[0047] The system is simplified into a two-port network consisting of an equivalent AC source connected in sequence, a hybrid topology, and an equivalent load resistor R eq , where the equivalent AC source is a DC current source U dc The equivalent load resistance R eq The push-pull rectifier and load resistor R L The whole is equivalent;

[0048] constructing a transfer model of the two-port network according to the two-port network;

[0049] A transfer function between an output voltage and an output current of the current source inverter is obtained according to the transfer model.

[0050] In the following example analysis, the nonlinearity of the rectifier part is ignored. The rectifier part is equivalent to the load and does not affect the analysis of the system's stable autonomous oscillation frequency.

[0051] Assuming that the internal resistance of the component and the forward voltage drop of the diode are both 0, in steady state, the current flowing through L dc1 , L a , L b , L c , L d and L dc2 The current can be regarded as a constant current. The output of the push-pull inverter can be equivalent to a square wave current source.

[0052] When the input voltage U2 of the push-pull rectifier is less than 0, the inductor L dThe voltage across the two ends is close to the system output voltage U out When U2 is greater than 0, L d The voltage across the two ends is U Ld :

[0053] U Ld =U out -U2=U out -U 2m sin(ωt) (1)

[0054] Among them, U 2m represents the peak value of U2, and ω represents the operating frequency of the system.

[0055] Since in steady state, the inductor L d The voltage integral in one cycle is 0, so U Ld This can be integrated and set to 0 in a loop:

[0056]

[0057] The relationship between the voltages can be obtained:

[0058] U 2m =πU out (3)

[0059] Based on the consistent power consumption, the equivalent load resistance of the rectifier link is calculated as follows:

[0060]

[0061] Based on the above equivalence, Figure 1 The simplified model is as follows Figure 3 As shown, I represents the DC current source U dc The equivalent AC source equivalent to the push-pull inverter has a voltage across it represented by U1(s), a current represented by I1(s), and an equivalent load resistance R eq The input voltage and current are expressed as U2(s) and I2(s) respectively, where s represents a complex variable (=jω). p1 , L p2 , L s1 , L s2 The equivalent series resistance is represented by R p1 , R p2 , R s1 , R s2 .

[0062] Figure 3 The simplified model shown is expressed in the form of a two-port network:

[0063]

[0064] Among them, Y 11 (s), Y 12 (s), Y 21 (s), Y 22 (s) is the admittance function, Specifically, Y 11 (s), Y 12 (s), Y 21 (s), Y 22 (s) is expressed as:

[0065]

[0066]

[0067] Among them, the parameters △1 and △2 that are customized to simplify the formula expression are expressed as:

[0068]

[0069]

[0070] The output side is equivalent to a resistor, then:

[0071] U2(s)=-R eq I2(s) (11)

[0072] Combining equations (5), (6), (7) and (8), we can obtain the transfer function G(s) between U1(s) and I1(s):

[0073]

[0074] According to the characteristics of the system, the structure diagram of the system can be obtained, such as Figure 4 As shown, M represents the input current value during mode switching, A represents the fundamental amplitude of the input quantity of the nonlinear element, and N(A) represents the nonlinear component of the system:

[0075]

[0076] Then, the stability at the corresponding operating frequency can be determined according to the describing function method, where L p1 =L s1 =L1,L p2 =L s2 =L2,C p1 =C s1 =C1,C p2 =C s2 =C2, we can get Figure 5 The frequency characteristic curve shown is Figure 5(a) and (b) are polar coordinate diagrams with ESR (equivalent series resistance) ignored and ESR introduced, respectively. Figure 5 As shown in (a), the -1 / N(A) curve and the transfer function curve have seven frequency intersections f1 to f7. According to the stability analysis method of autonomous oscillation, f1, f3, f5, and f7 correspond to stable autonomous oscillation operating points. Figure 5 It can be seen from (a) that the values ​​corresponding to the seven frequency points are the frequency points when the phase of the system phase-frequency characteristic is 0, that is, Therefore, the frequency can be solved by the following expression:

[0077] (a1ω 8 +b1ω 6 +c1ω 4 +d1ω 2 +e1)(a2ω 6 +b2ω 4 +c2ω 2 +d2)=0 (14)

[0078] Among them, the parameters a1, b1, c1, d1, e1, a2, b2, c2, and d2 customized to simplify the formula are as follows:

[0079]

[0080] The frequencies can be obtained by solving equation (14) separately.

[0081] According to equation (5), the relationship between U2(s) and U1(s) can be obtained:

[0082]

[0083] Substitute the frequency of the autonomous oscillation point to obtain the output voltage gain A(ω) at the stable operating frequency point ω:

[0084] A(ω)=|G2(jω)| (17)

[0085] The above analysis is based on ideal conditions. Under ideal conditions, the system gain A(ω1,ω3,ω5,ω7) = 1. However, considering that the ESR of the inductor in the actual system cannot be ignored, we can obtain Figure 5 The amplitude-phase-frequency characteristic curve (b) shows that the system stable operating frequency point is unique (f5, which is closest to 1). According to equation (17), the system gain during stable operation can be obtained.

[0086] The system gain curves when ESR is introduced and ESR is ignored when the load changes are as follows Figure 6 According to the mathematical model, the proposed system can achieve large-scale decoupling with the variation of coupling coefficient, self-inductance and load parameters.

[0087] It should also be noted that the hybrid topology of this embodiment takes the dual orthogonal DD coupling mechanism and the PP-SS compensation topology as an example, and in other implementations, other hybrid topologies may be used, and the corresponding Y 11 (s), Y 12 (s), Y 21 (s), Y 22 (s) will change.

[0088] In order to verify the correctness of the model, an experimental device is constructed in this example. The transmitting and receiving coils are wound with orthogonal DD coils to suppress cross-coupling between the coils. The parameter settings of the device are shown in Table 1. In order to ensure that the inverter output current is close to a square wave and reduce the influence of the phase inductance on resonance, the values ​​of the DC inductance and the phase inductance should be as large as possible. In addition, considering the influence of the inductor ESR on efficiency and the fact that excessive inductance reduces the system response speed, the DC inductance and the phase inductance in this design are about 10 times the coil inductance. According to the range of self-inductance and mutual inductance of the system coil and the load requirements, the value of the compensation capacitor is set by the formula, and the appropriate capacitance is selected by comprehensively considering the needs of efficiency and decoupling range.

[0089] Table 1 System parameters

[0090]

[0091] In the experiment, the voltage waveform and driving waveform at both ends of the switch tube can be obtained, such as Figure 7 As shown, the autonomous system can spontaneously achieve ZVS soft switching.

[0092] By changing the distance between the transmitter and the receiver, the relationship between the coil self-inductance, coupling coefficient and transmission distance is measured, such as Figure 8 As shown. Figure 8 It can be seen that as the wireless transmission distance continues to increase, the mutual inductance of the four energy transmission coils gradually decreases, and the coupling coefficients k1 and k2 between the two pairs of coils gradually decrease to close to 0.

[0093] Fig. 9 For R L =100Ω, the experimental and calculated system gain at different coupling coefficients and operating frequencies. Fig. 9 It can be seen that when the coupling coefficient is 0.05, the system gain is 0.9. When the coupling coefficient increases, the system gain is about 1, which is decoupled from the self-inductance and the coupling coefficient, achieving a wide range of decoupling. This is consistent with the theoretical calculation results, and verifies the effectiveness of the frequency-autonomous wireless power transmission system with wide-range decoupling proposed in the present invention in achieving decoupling under a wide range of coupling coefficient changes.

[0094] The load is changed to 50Ω, and the experimental and calculated system gain results at different coupling coefficients and operating frequencies are as follows Fig.10 As shown, from Fig.10 It can be seen that the experimental results are consistent with the theoretical analysis results, which proves the effectiveness of the frequency autonomous wireless power transmission system with wide range decoupling proposed by the present invention in achieving decoupling under system load changes.

[0095] The efficiency curves under different coupling coefficients under different loads are as follows: Fig.11 As shown. Fig.11 It can be seen that when the coupling coefficient is higher than 0.1, the average transmission efficiency can reach no less than 80%. At 50Ω, the maximum efficiency can reach 89.3%. This proves that the frequency-autonomous wireless power transmission system with wide-range decoupling proposed in the embodiment of the present invention can achieve higher-efficiency power transmission under changes in system load and wide-range changes in coupling coefficient.

[0096] In summary, the wide-range decoupled frequency autonomous wireless power transmission system proposed in the embodiment of the present invention adopts a DC current source as the power supply at the transmitting end, and the current-type inverter and the push-pull rectifier adopt an autonomous push-pull circuit with the same circuit structure, and the system stable autonomous oscillation frequency that enables the system to have autonomous oscillation stability characteristics is obtained through adaptive calculation of the current system parameters (unchanged parameters and changing mutual inductance and load) to drive the switch tubes of the current-type inverter and the push-pull rectifier, thereby realizing system decoupling under wide-range changes in coupling coefficient and load, and realizing high-efficiency power transmission under wide-range changes in coupling coefficient and load. The experimental results are consistent with the theoretical results, which confirms the effectiveness of the wide-range decoupled frequency autonomous wireless power transmission system proposed in the embodiment of the present invention in decoupling under wide-range changes in coupling coefficient and load to achieve high-efficiency power transmission.

[0097] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A frequency autonomous wireless power transmission system with wide range decoupling, characterized by: Including the DC current source U connected in series dc , current source inverter, hybrid topology, push-pull rectifier and load resistor R L ; The DC current source U dc The current source inverter is input, and after being transformed by the current source inverter, a square wave current source is output to the hybrid topology; the hybrid topology wirelessly couples energy to the push-pull rectifier; the push-pull rectifier realizes AC to DC conversion, and the load resistor R L power supply; the current source inverter and the push-pull rectifier adopt an autonomous push-pull circuit with the same circuit structure and are symmetrically connected in the system.

2. A frequency autonomous wireless power transmission system with wide range decoupling according to claim 1, characterized in that: The current-type inverter is provided with a transmitting-end switch tube control circuit, and the push-pull rectifier is provided with a receiving-end switch tube control circuit. The transmitting-end switch tube control circuit or the receiving-end switch tube control circuit is used to calculate the system stable autonomous oscillation frequency according to the current parameters of the system. The transmitting-end switch tube control circuit and the receiving-end switch tube control circuit respectively drive the switch tubes in the current-type inverter and the push-pull rectifier with the system stable autonomous oscillation frequency.

3. A frequency autonomous wireless power transmission system with wide range decoupling according to claim 2, characterized in that: The steps for calculating the system's stable autonomous oscillation frequency based on the system's current parameters include: Determining a transfer function between an output voltage and an output current of the current source inverter according to a circuit structure of the system; Let the phase of the transfer function's phase-frequency characteristic be 0, substitute the current system parameters, and solve for multiple frequencies; The system output voltage gain at multiple frequencies is calculated and solved, and the frequency with the maximum system output voltage gain is determined as the system stable autonomous oscillation frequency.

4. A frequency autonomous wireless power transmission system with wide range decoupling according to claim 3, characterized in that: The autonomous push-pull circuit comprises a DC inductor, a first phase-divided inductor, a second phase-divided inductor, a first switch tube, a second switch tube and a switch tube control circuit, wherein one end of the DC inductor is connected to a DC current source U dc or load resistance R L The other end of the DC inductor is connected to the common connection end of the first phase-divided inductor and the second phase-divided inductor, the other end of the first phase-divided inductor is connected to the drain of the first switch tube as the first AC output end or the first AC input end, and the other end of the second phase-divided inductor is connected to the drain of the second switch tube as the second AC output end or the second AC input end. The gate and drain of the first switch tube and the gate and drain of the second switch tube are also connected to the transmitting end switch tube control circuit or the receiving end switch tube control circuit. The transmitting end switch tube control circuit or the receiving end switch tube control circuit is used to calculate the system stable autonomous oscillation frequency according to the current parameters of the system and alternately connect the first switch tube and the second switch tube at the frequency to realize DC to AC or AC to DC.

5. A frequency autonomous wireless power transmission system with wide range decoupling according to claim 4, characterized in that: The hybrid topology adopts a dual orthogonal DD coupling mechanism and a PP-SS compensation topology; the dual orthogonal DD coupling mechanism includes a DD transmitting coil and a DD receiving coil, wherein the DD transmitting coil includes a D-type first transmitting coil L connected in series p1 and the D-type second transmitting coil L p2 , the DD type receiving coil comprises a D type first receiving coil L connected in series s1 and the D-type second receiving coil L s2 The PP-SS compensation topology includes a D-type first transmitting coil L p1 Parallel transmitter parallel compensation capacitor C p1 , and the D-type second transmitting coil L p2 The transmitter series compensation capacitor C p2 , and the D-type first receiving coil L s1 The parallel compensation capacitor C of the receiving end s1 , and the D-type second receiving coil L s2 The receiving end series compensation capacitor C s2 The first and second AC output terminals of the current source inverter are respectively connected to the D-type first transmitting coil L p1 One end and the other end of the D-type first transmitting coil L p1 The other end is also connected in series with the D-type second transmitting coil L p2 And the transmitter series compensation capacitor C p2 The first and second AC input ends of the push-pull rectifier are respectively connected to the D-type first receiving coil L s1 One end and the other end of the D-type first receiving coil L s1 The other end is also connected in series with the D-type second receiving coil L s2 And the receiving end series compensation capacitor C s2 Then connected to the first AC input end of the push-pull rectifier.

6. A frequency autonomous wireless power transmission system with wide range decoupling according to claim 5, characterized in that: Determining the transfer function between the output voltage and the output current of the current source inverter according to the circuit structure of the system specifically comprises the steps of: The system is simplified into a two-port network consisting of an equivalent AC source connected in sequence, a hybrid topology, and an equivalent load resistor R eq , where the equivalent AC source is a DC current source U dc The equivalent load resistance R eq The push-pull rectifier and load resistor R L The whole is equivalent; constructing a transfer model of the two-port network according to the two-port network; A transfer function between an output voltage and an output current of the current source inverter is obtained according to the transfer model.

7. A frequency autonomous wireless power transmission system with wide range decoupling according to claim 6, characterized in that: The transfer model of the two-port network is expressed as: Among them, U1(s) and I1(s) represent the output voltage and current of the equivalent AC source related to the complex variable s, and U2(s) and I2(s) represent the equivalent load resistance R eq Input voltage and current, Y 11 (s), Y 12 (s), Y 21 (s), Y 22 (s) is the admittance function, 8. A frequency autonomous wireless power transmission system with wide range decoupling according to claim 7, characterized in that: The transfer function between the output voltage and output current of the current source inverter is U2(s):I1(s), which is equal to (1+R eq Y 22 (s)):(R eq Y 11 (s)Y 22 (s)+R eq Y 12 (s)Y 21 (s)+Y 11 (s)).

9. A frequency autonomous wireless power transmission system with wide range decoupling according to claim 8, characterized in that: The system output voltage gain at frequency ω is calculated as A(ω)=|G2(s)|, where G2(s) represents the ratio of U2(s) to I2(s), and || represents the modulus.

10. A frequency autonomous wireless power transmission system with wide range decoupling according to claim 9, characterized in that: The ratio of U2(s) to I2(s) is equal to Y 12 (s)R eq :(Y 22 (s)R eq +1).

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