A wide-range decoupled frequency autonomous wireless power transfer system

Abstract

This invention relates to the field of wireless power transfer technology, specifically disclosing a wide-range decoupled frequency-autonomous wireless power transfer system. The transmitter uses a DC current source, and the current-source inverter and push-pull rectifier employ an autonomous push-pull circuit with the same circuit structure. A stable autonomous oscillation frequency is adaptively calculated based on current system parameters (unchanging parameters and varying mutual inductance and load) to drive the switching transistors of the current-source inverter and push-pull rectifier. This achieves system decoupling under a wide range of coupling coefficient and load variations, resulting in high-efficiency power transfer. Experimental results are consistent with theoretical results, confirming the effectiveness of the wide-range decoupled frequency-autonomous wireless power transfer system proposed in this invention in achieving high-efficiency power transfer under wide-range coupling coefficient and load variations.

Description

Technical Field

[0001] This invention relates to the field of wireless power transmission technology, and more particularly to a wide-range decoupled frequency autonomous wireless power transmission system. Background Technology

[0002] In recent years, inductive wireless power transfer (WPT) systems have been successfully applied in electric vehicles, drones, and mobile wireless charging 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, due to misalignment of the coupling mechanism, environmental factors, and load variations, unavoidable changes in these parameters can lead to system detuning. This results in reduced smoothness of the system output voltage, increased power loss, and decreased system stability. To ensure stable system output and improve the flexibility of power transfer, the system's tolerance to misalignment errors must be increased.

[0003] Methods to address parameter deviations and maintain output stability in WPT systems primarily include improving coil structure, optimizing topology design, or adding control mechanisms to stabilize the output. Among these, optimizing topology design is a relatively effective approach. Introducing hybrid topologies can improve the tolerance of WPT systems to misalignment errors. However, most existing hybrid compensation topologies are driven by fixed frequency and voltage. Large DC-side capacitors limit the types of compensation topologies that can be hybridized, resulting in poor dynamic performance and adaptability to parameter variations, failing to meet the requirements of misalignment tolerance and large-scale decoupling in WPT systems. Summary of the Invention

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

[0005] To address the above technical problems, this invention provides a wide-range decoupled frequency-autonomous wireless power transfer system, comprising sequentially connected DC current sources U dc Current-source inverters, hybrid topologies, push-pull rectifiers, and load resistors R L The DC current source U dc The current-source inverter is input, and after conversion by the current-source inverter, it outputs a square wave current source 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 is the load resistor R. L Power supply; the current-source inverter and the push-pull rectifier adopt the same autonomous push-pull circuit structure and are symmetrically connected in the system.

[0006] Preferably, the current-source inverter is provided with a transmitter switch control circuit, and the push-pull rectifier is provided with a receiver switch control circuit. The transmitter switch control circuit or the receiver switch control circuit is used to calculate the system's stable autonomous oscillation frequency based on the current system parameters. The transmitter switch control circuit and the receiver switch control circuit drive the switches in the current-source inverter and the push-pull rectifier respectively with the system's stable autonomous oscillation frequency.

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

[0008] Determine the transfer function between the output voltage and output current of the current-source inverter based on the system's circuit structure;

[0009] Set the phase of the phase frequency response of the transfer function to 0, substitute the current parameters of the system, and solve to obtain multiple frequencies;

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

[0011] Preferably, the autonomous push-pull circuit includes a DC inductor, a first phase-splitting inductor, a second phase-splitting inductor, a first switching transistor, a second switching transistor, and a switching transistor 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 terminal of the first phase-separating inductor and the second phase-separating inductor. The other end of the first phase-separating inductor serves as the first AC output terminal or the first AC input terminal and is connected to the drain of the first switching transistor. The other end of the second phase-separating inductor serves as the second AC output terminal or the second AC input terminal and is connected to the drain of the second switching transistor. The gate and drain of the first switching transistor and the gate and drain of the second switching transistor are also connected to the transmitter switching transistor control circuit or the receiver switching transistor control circuit. The transmitter switching transistor control circuit or the receiver switching transistor control circuit is used to calculate the stable autonomous oscillation frequency of the system based on the current parameters of the system and alternately turn on the first switching transistor and the second switching transistor at this frequency to realize DC to AC or AC to DC conversion.

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

[0013] Preferably, determining the transfer function between the output voltage and output current of the current-source inverter based on the system's circuit structure specifically includes the following steps:

[0014] The system is simplified to a two-port network, which includes sequentially connected equivalent AC sources, a hybrid topology, and an equivalent load resistance R. eq The equivalent AC source is composed of a DC current source U. dc It is equivalent to a current-source inverter, with an equivalent load resistance R. eq Composed of a push-pull rectifier and a load resistor R L Equivalent to the whole;

[0015] Construct the transmission model of the two-port network based on the two-port network;

[0016] The transfer function between the output voltage and output current of the current-source inverter is obtained based on the transfer model.

[0017] Preferably, the transmission model of the two-port network is represented as follows:

[0018]

[0019] Where 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, respectively. eq The 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 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 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] This invention provides a wide-range decoupled frequency-autonomous wireless power transfer system. The transmitter uses a DC current source, and the current-source inverter and push-pull rectifier employ an autonomous push-pull circuit with the same circuit structure. A stable autonomous oscillation frequency is adaptively calculated based on current system parameters (unchanging parameters and varying mutual inductance and load) to drive the switching transistors of the current-source inverter and push-pull rectifier. This achieves system decoupling under a wide range of coupling coefficient and load variations, resulting in high-efficiency power transfer. Experimental results are consistent with theoretical results, confirming the effectiveness of the wide-range decoupled frequency-autonomous wireless power transfer system proposed in this invention in achieving high-efficiency power transfer under wide-range coupling coefficient and load variations. Attached Figure Description

[0024] Figure 1 This is a circuit diagram of a wide-range decoupled frequency autonomous wireless power transmission system provided in an embodiment of the present invention;

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

[0026] Figure 3 This is provided by the embodiments of the present invention. Figure 1 A simplified model diagram;

[0027] Figure 4 This is a transmission model diagram of the system provided in the embodiments of the present invention;

[0028] Figure 5 This is a frequency response polar plot provided in an embodiment of the present invention, where (a) and (b) correspond to ignoring ESR and introducing ESR, respectively;

[0029] Figure 6 This is a system gain curve diagram showing the effects of ignoring ESR and introducing ESR under load changes, provided in an embodiment of the present invention.

[0030] Figure 7 These are experimental waveform diagrams provided in the embodiments of the present invention;

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

[0032] Figure 9 This is a gain diagram of the system with a load of 100Ω under different coupling coefficients and operating frequencies provided in an embodiment of the present invention;

[0033] Figure 10 This is a gain diagram of the system with a load of 50Ω under different coupling coefficients and operating frequencies provided in an embodiment of the present invention;

[0034] Figure 11 This is an efficiency curve diagram under different loads provided in the embodiments of the present invention. Detailed Implementation

[0035] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. The embodiments are given for illustrative purposes only and should not be construed as limiting the present invention. The accompanying drawings are 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] This invention provides a wide-range decoupled frequency-autonomous wireless power transfer system, such as... Figure 1 As shown, it includes DC current sources U connected in sequence. dc Current-source inverters, hybrid topologies, push-pull rectifiers, and load resistors R L DC current source Udc The input current-source inverter converts the current to output a square wave current source, which is then fed into the hybrid topology. The hybrid topology wirelessly couples the energy to a push-pull rectifier. The push-pull rectifier converts AC to DC, acting as a load resistor R. L powered by.

[0037] In this system, the current-source inverter and the push-pull rectifier employ an autonomous push-pull circuit with the same circuit structure. The current-source inverter is used for DC-AC conversion, and the push-pull rectifier is used for AC-DC conversion. They are symmetrically connected in the WPT system. The autonomous push-pull circuit is a soft-switching circuit, a current-source circuit, including a DC inductor, a first phase-splitting inductor, a second phase-splitting inductor (the first and second phase-splitting inductors form a phase-splitting inductor for current phase splitting), a first switch, a second switch, and a switch control circuit. 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 terminal of the first phase-separating inductor and the second phase-separating inductor. The other end of the first phase-separating inductor serves as the first AC output terminal or the first AC input terminal and is connected to the drain of the first switching transistor. The other end of the second phase-separating inductor serves as the second AC output terminal or the second AC input terminal and is connected to the drain of the second switching transistor. The gate and drain of the first switching transistor and the gate and drain of the second switching transistor are also connected to the transmitter switching transistor control circuit or the receiver switching transistor control circuit. The transmitter switching transistor control circuit or the receiver switching transistor control circuit is used to calculate the stable autonomous oscillation frequency of the system based on the current parameters of the system and alternately turn on the first switching transistor and the second switching transistor at this frequency to realize DC to AC or AC to DC conversion.

[0038] like Figure 1 As shown, the current-source inverter specifically includes a DC inductor L dc1 Phase-separated first inductor L a Phase split second inductor L b (Phase-separated first inductor L) a and the second inductor L b (Forming a phase-splitting inductor for current phase splitting), the control circuit for the first switch Q1, the second switch Q2, and the transmitter switch, wherein the DC inductor L... dc1 One end is connected to a DC current source U dc DC inductor L dc1 The other end is connected to the first inductor L. a Phase split second inductor L b The common connection terminal, phase separation first inductor L a The other end serves as the first AC output terminal, connected to the drain of the first switching transistor Q1, and is connected to the second inductor L. bThe other end serves as the second AC output terminal, connected to the drain of the second switch Q2. The gate and drain of the first switch Q1, as well as the gate and drain of the second switch Q2, are also connected to the transmitter switch control circuit. The transmitter switch control circuit calculates the system's stable autonomous oscillation frequency and alternately switches on the first switch Q1 and the second switch Q2 at this frequency to achieve DC-to-AC conversion. DC power supply U dc and DC inductor L dc1 Together they form a quasi-DC power supply. Inductor L a and L b A phase-splitting inductor is formed, and the switching transistors Q1 and Q2, together with the phase-splitting inductor, constitute a push-pull inverter. The autonomous push-pull circuit utilizes the natural zero-crossing torque of the power flow to achieve a flexible energy conversion process, enabling frequency adaptation under stable system conditions. Its basic principle is that when the voltage across the parallel capacitor crosses zero, the switching transistors alternately turn on. Under steady-state operation, the phase-splitting inductor current is approximately constant, thus 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-separated first inductor L d Phase split second inductor L c (Phase-separated first inductor L) d and the second inductor L c (Forming a phase-splitting inductor for current phase splitting), the control circuit for the first switch Q4, the second switch Q3, and the receiving end switch, wherein the DC inductor L... dc2 One end is connected to the load resistor R L DC inductor L dc2 The other end is connected to the first inductor L. d Phase split second inductor L c The common connection terminal, phase separation first inductor L d The other end serves as the first AC input terminal, connected to the drain of the first switching transistor Q4, and is connected to the second inductor L. c The other end serves as the second AC input terminal, connected to the drain of the second switching transistor Q3. The gate and drain of the first switching transistor Q4, as well as the gate and drain of the second switching transistor Q3, are also connected to the receiving-end switching transistor control circuit. The receiving-end switching transistor control circuit calculates the system's stable autonomous oscillation frequency and alternately switches on the first switching transistor Q4 and the second switching transistor Q3 at this frequency to achieve AC-to-DC conversion. The push-pull rectifier operates on the same principle as a current-source inverter.

[0040] To facilitate wide-range decoupling, embodiments of the present invention provide a frequency-autonomous wireless power transfer system with wide-range decoupling, such as... Figure 1As shown, its hybrid topology employs a biorthogonal DD-type coupling mechanism and a PP-SS compensation topology. The biorthogonal DD-type coupling mechanism includes a DD-type transmitting coil and a DD-type receiving coil, wherein the DD-type transmitting coil includes a first D-type transmitting coil L connected in series. p1 and D-type second transmitting coil L p2 The DD-type receiving coil includes a first D-type receiving coil L connected in series. s1 and D-type second receiving coil L s2 The PP-SS compensation topology includes the D-type first transmitting coil L. p1 Parallel compensation capacitor C at the transmitter p1 (P type), with D type second transmitting coil L p2 Series-connected transmitter compensation capacitor C p2 (S-type), and the first receiving coil L of the D-type s1 Parallel compensation capacitor C at the receiving end s1 (P type), with D type second receiving coil L s2 Series-connected compensation capacitor C at the receiver end s2 (S-type). The first and second AC output terminals of the current-source inverter are respectively connected to the first transmitting coil L of the D-type inverter. p1 One end and the other end, D-type first transmitting coil L p1 The other end is also connected to a second D-type transmitting coil L connected in series. p2 The compensation capacitor C connected in series with the transmitter p2 The first AC output terminal of the current-source inverter is then connected. The first and second AC input terminals of the push-pull rectifier are respectively connected to the first receiving coil L of the D-type rectifier. s1 One end and the other end, D-type first receiving coil L s1 The other end is also connected to a second D-type receiving coil L connected in series. s2 The compensation capacitor C is connected in series with the receiving end. s2 The first AC input terminal of the push-pull rectifier is then connected. Due to the decoupling characteristics of the orthogonal DD-type coils, only the non-orthogonal D-type first transmitting coil L exists between the two orthogonal DD-type coupling mechanisms. p1 and D-type first receiving coil L s1 Mutual inductance M1 and non-orthogonal D-type second transmitting coil L p2 and D-type second receiving coil L s2 Mutual inductance M2 between them.

[0041] In this example, the four energy transfer coils use coils with identical parameters and have self-inductance L. p1 =L p2 =L s1 =L s2 .

[0042] Figure 2The system's seven frequency response curves are displayed, representing the system's inherent fully resonant frequencies as the coil's self-inductance and coupling coefficient change. Here, f5 is the system's stable operating frequency, i.e., the stable autonomous oscillation frequency, at which the system's output gain remains constant over a wide range. The following analyzes how to determine the system's stable autonomous oscillation frequency; the general steps include:

[0043] Determine the transfer function between the output voltage and output current of the current-source inverter based on the system's circuit structure;

[0044] Set the phase of the phase frequency response of the transfer function to 0, substitute the current parameters of the system, and solve to obtain multiple frequencies;

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

[0046] Determining the transfer function between the output voltage and output current of the current-source inverter based on the system's circuit structure specifically includes the following steps:

[0047] The system is simplified to a two-port network, which includes sequentially connected equivalent AC sources, a hybrid topology, and an equivalent load resistance R. eq The equivalent AC source is composed of a DC current source U. dc It is equivalent to a current-source inverter, with an equivalent load resistance R. eq Composed of a push-pull rectifier and a load resistor R L Equivalent to the whole;

[0048] Construct the transmission model of the two-port network based on the two-port network;

[0049] The transfer function between the output voltage and output current of the current-source inverter is obtained based on the transfer model.

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

[0051] Assuming the internal resistance of the component and the forward voltage drop of the diode are both zero, under steady state, the current flowing through L... dc1 L a L b L c L d and L dc2 The current can be considered a constant current. The output of a 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 terminals is close to the system output voltage U. out When U2 is greater than 0, L d The voltage across the terminals is U Ld :

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

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

[0055] Because under steady state, the inductance L d The voltage integral over one cycle is 0, therefore U Ld You can integrate within a loop and set it to 0:

[0056]

[0057] The relationship between voltages can be obtained:

[0058] U 2m =πU out (3)

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

[0060]

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

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

[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 represented as:

[0065]

[0066]

[0067] To simplify the formula, the custom parameters △1 and △2 are represented as follows:

[0068]

[0069]

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

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

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

[0073]

[0074] Based on the characteristics of the system, a system structure diagram 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] Subsequently, the stability at the corresponding operating frequency can be determined using 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 response curve shown is as follows. Figure 5(a) and (b) represent polar plots with and without ESR (equivalent series resistance), respectively. Figure 5 As shown in (a), the -1 / N(A) curve and the transfer function curve have seven frequency intersection points f1 to f7. According to the stability analysis method of autonomous oscillation, f1, f3, f5, and f7 correspond to the stable autonomous oscillation operating points. Figure 5 As can be seen from (a), the values ​​corresponding to the seven frequency points are the frequency points where the phase of the system's 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] The parameters a1, b1, c1, d1, e1, a2, b2, c2, and d2, defined to simplify the formula, are as follows:

[0079]

[0080] The frequency 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] Substituting the frequency of the autonomous oscillation point, we 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 which the system gain A(ω1,ω3,ω5,ω7) = 1. However, considering that the ESR of the inductor in a real system cannot be ignored, we can obtain... Figure 5 The amplitude-phase frequency response curve shown in (b) indicates that the stable operating frequency of the system is uniquely determined (f5, with the closest being 1). The system gain during stable operation can be obtained according to equation (17).

[0086] The system gain curves with and without ESR under load variation are shown below. Figure 6 As shown. According to the mathematical model, the proposed system can achieve large-scale decoupling under varying coupling coefficients, self-inductance, and load parameters.

[0087] It should also be noted that the hybrid topology in this embodiment uses a biorthogonal DD-type coupling mechanism and a PP-SS compensation topology as examples. In other embodiments, other hybrid topologies can be used, with corresponding Y... 11 (s), Y 12 (s), Y 21 (s), Y 22 (s) will change.

[0088] To verify the model's correctness, an experimental setup was constructed. The transmitting and receiving coils were wound with orthogonal DD coils to suppress cross-coupling between them. The setup parameters are shown in Table 1. To ensure the inverter output current is close to a square wave and to reduce the impact of the phase inductance on resonance, the values ​​of the DC inductance and phase inductance should be as large as possible. Furthermore, considering the impact of inductance ESR on efficiency and the reduced system response speed due to excessive inductance, the DC inductance and phase inductance in this design are approximately 10 times the coil inductance. Based on the range of self-inductance and mutual inductance variations of the system coils and the load requirements, the value of the compensation capacitor was set using formulas. Taking into account both efficiency and decoupling range requirements, an appropriate capacitance value was selected.

[0089] Table 1 System Parameters

[0090]

[0091] In the experiment, the voltage waveform and drive waveform across the switching transistor can be obtained, such as... Figure 7 As shown, autonomous systems can spontaneously implement ZVS soft switching.

[0092] By varying the distance between the transmitter and receiver, the relationship between coil self-inductance, coupling coefficient, and transmission distance can be measured, such as... Figure 8 As shown. From 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] Figure 9 For R L The experimental and calculated system gain at different coupling coefficients and operating frequencies when the Ω is 100Ω. Based on... Figure 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. This decouples the system from the self-inductance and the coupling coefficient, achieving wide-range decoupling. This is consistent with the theoretical calculation results, verifying the effectiveness of the frequency autonomous wireless power transmission system with wide-range decoupling proposed in this invention in achieving decoupling under a wide range of coupling coefficient variations.

[0094] With the load changed to 50Ω, the experimental and calculated system gain results under different coupling coefficients and operating frequencies are as follows: Figure 10 As shown, from Figure 10 As can be seen, the experimental results are consistent with the theoretical analysis. This proves the effectiveness of the wide-range decoupled frequency autonomous wireless power transfer system proposed in this invention in achieving decoupling under varying system loads.

[0095] Efficiency curves under different loads and coupling coefficients are shown below. Figure 11 As shown. From Figure 11 As can be seen, an average transmission efficiency of no less than 80% can be achieved when the coupling coefficient is higher than 0.1, and the maximum efficiency can reach 89.3% at 50Ω. This proves that the wide-range decoupled frequency autonomous wireless power transmission system proposed in this embodiment of the invention can achieve high-efficiency power transmission under system load changes and wide-range coupling coefficient changes.

[0096] In summary, the wide-range decoupled frequency-autonomous wireless power transfer system proposed in this invention uses a DC current source as the power supply at the transmitting end. The current-source inverter and push-pull rectifier employ an autonomous push-pull circuit with the same circuit structure. The system's stable autonomous oscillation frequency, which enables autonomous oscillation stability, is adaptively calculated based on current system parameters (unchanging parameters and varying mutual inductance and load) to drive the switching transistors of the current-source inverter and push-pull rectifier. This achieves system decoupling under a wide range of coupling coefficient and load variations, resulting in high-efficiency power transfer. Experimental results are consistent with theoretical results, confirming the effectiveness of the wide-range decoupled frequency-autonomous wireless power transfer system proposed in this invention in achieving high-efficiency power transfer under wide-range coupling coefficient and load variations.

[0097] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A wide-range decoupled frequency-autonomous wireless power transfer system, characterized in that: Including sequentially connected DC current sources Current-source inverters, hybrid topologies, push-pull rectifiers, and load resistors The DC current source The current-source inverter is input, and after conversion by the current-source inverter, it outputs a square wave current source 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 serves as the load resistor. 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; The hybrid topology employs a biorthogonal DD-type coupling mechanism and a PP-SS compensation topology; the biorthogonal 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 connected in series. and Type D second transmitting coil The DD-type receiving coil includes a first D-type receiving coil connected in series. and D-type second receiving coil The PP-SS compensation topology includes a D-type first transmitting coil. Parallel compensation capacitors at the transmitter With the second transmitting coil of type D Series-connected transmitter compensation capacitor With the first receiving coil of type D Parallel compensation capacitors at the receiving end With the D-type second receiving coil Series-connected compensation capacitor at the receiver end The first and second AC output terminals of the current-source inverter are respectively connected to the first D-type transmitting coil. One end and the other end, type D first transmitting coil The other end is also connected to a second D-type transmitting coil connected in series. series compensation capacitor with transmitter The first AC output terminal of the current-source inverter is connected to the first AC output terminal; the first and second AC input terminals of the push-pull rectifier are respectively connected to the first receiving coil of the D type. One end and the other end, D-type first receiving coil The other end is also connected to a second D-type receiving coil connected in series. series compensation capacitor with the receiver Then connect to the first AC input terminal of the push-pull rectifier; The current-source inverter is provided with a transmitter switch control circuit, and the push-pull rectifier is provided with a receiver switch control circuit. The transmitter switch control circuit or the receiver switch control circuit is used to calculate the system's stable autonomous oscillation frequency based on the current system parameters. The transmitter switch control circuit and the receiver switch control circuit drive the switches in the current-source inverter and the push-pull rectifier respectively with the system's stable autonomous oscillation frequency. The steps for calculating the stable autonomous oscillation frequency of the system based on the current system parameters include: Determine the transfer function between the output voltage and output current of the current-source inverter based on the system's circuit structure; Set the phase of the phase frequency response of the transfer function to 0, substitute the current parameters of the system, and solve for multiple frequencies; The system output voltage gain at multiple frequencies is calculated, and the frequency with the largest system output voltage gain is determined as the system's stable autonomous oscillation frequency.

2. The wide-range decoupled frequency autonomous wireless power transfer system according to claim 1, characterized in that: The autonomous push-pull circuit includes a DC inductor, a first phase-separating inductor, a second phase-separating inductor, a first switching transistor, a second switching transistor, and a switching transistor control circuit, wherein one end of the DC inductor is connected to a DC current source. or load resistor The other end of the DC inductor is connected to the common connection terminal of the first phase-separating inductor and the second phase-separating inductor. The other end of the first phase-separating inductor serves as the first AC output terminal or the first AC input terminal and is connected to the drain of the first switching transistor. The other end of the second phase-separating inductor serves as the second AC output terminal or the second AC input terminal and is connected to the drain of the second switching transistor. The gate and drain of the first switching transistor and the gate and drain of the second switching transistor are also connected to the transmitter switching transistor control circuit or the receiver switching transistor control circuit. The transmitter switching transistor control circuit or the receiver switching transistor control circuit is used to calculate the stable autonomous oscillation frequency of the system based on the current parameters of the system and alternately turn on the first switching transistor and the second switching transistor at this frequency to realize DC to AC or AC to DC conversion.

3. The wide-range decoupled frequency autonomous wireless power transfer system according to claim 1, characterized in that, Determining the transfer function between the output voltage and output current of the current-source inverter based on the system's circuit structure specifically includes the following steps: The system is simplified to a two-port network, which includes sequentially connected equivalent AC sources, a hybrid topology, and equivalent load resistance. The equivalent AC source is composed of a DC current source. It is equivalent to a current-source inverter, with an equivalent load resistance. Composed of push-pull rectifier and load resistor Equivalent to the whole; Construct the transmission model of the two-port network based on the two-port network; The transfer function between the output voltage and output current of the current-source inverter is obtained based on the transfer model.

4. The wide-range decoupled frequency autonomous wireless power transfer system according to claim 3, characterized in that, The transmission model of the two-port network is represented as follows: in, , Representation and complex variables The output voltage and current of the relevant equivalent AC source, and They represent the equivalent load resistances respectively. The input voltage and current, , , , Let be the admittance function. , , , .

5. A wide-range decoupled frequency autonomous wireless power transfer system according to claim 4, characterized in that, The transfer function between the output voltage and output current of the current-source inverter is: ,equal .

6. A wide-range decoupled frequency autonomous wireless power transfer system according to claim 5, characterized in that, In frequency The system output voltage gain is calculated as follows: , express and The ratio, This indicates taking the modulus.

7. A wide-range decoupled frequency autonomous wireless power transfer system according to claim 6, characterized in that: and The ratio equals .

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