Real eigenstate MC-WPT system with efficient energy transmission over any distance

Abstract

The present invention relates to the technical field of magnetically coupled wireless power transmission (MC-WPT), and specifically discloses a real eigenstate MC-WPT system for efficient energy transmission within an arbitrary distance range, including a transmitting circuit, a receiving circuit, a compensation circuit and a control circuit; the transmitting circuit is provided with a transmitting coil, the receiving circuit is provided with a receiving coil, and the compensation circuit is provided with a compensation coil. The control circuit determines the control signal applied to the transmitting coil inverter and the compensation coil inverter according to the actual coupling situation, under the constraints of the optimal efficiency compensation strategy of the compensation coil, the power allocation strategy, the parameter conditions of the system resonance, the parameter setting conditions of the real eigenstate, and the zero phase angle characteristic, so as to realize the current of the compensation coil at the current amplitude ratio of the optimal power compensation by controlling the amplitude and phase of the voltage of the compensation coil, realize the energy transmission of the real eigenstate system within an arbitrary range, and improve the power output of the real eigenstate system.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetically coupled wireless power transmission (MC-WPT), and in particular to a real eigenstate MC-WPT system for efficient energy transmission within an arbitrary distance range. Background Art

[0002] Intelligent vehicles such as driverless cars have broad application prospects in the fields of transportation and logistics. Wireless power transmission (WPT) technology is an indispensable supporting technology for supporting unmanned operation and improving equipment endurance. Magnetic coupling wireless power transmission (MC-WPT) technology is currently the most mature and widely used WPT technology, and has gradually been applied to consumer electronics, household appliances, electric vehicles and other fields.

[0003] At present, most of the research on MC-WPT systems is aimed at magnetically coupled resonant systems with fixed operating frequencies. However, for equipment such as unmanned ground vehicles (UGVs), the operating conditions are accompanied by large coupling offsets, and it is necessary to ensure large power output and high transmission efficiency. The real eigenstate mode has incomparable advantages over the magnetically coupled resonant mode: 1) The operating frequency of the real eigenstate mode is always the resonant frequency of the system, the output current under system resonance is large, and the output power is high; 2) The impedance characteristic of the real eigenstate mode is always zero phase angle (ZPA), which can ensure that the system has a high transmission efficiency; 3) The real eigenstate mode does not require the addition of additional impedance matching networks and anti-offset coupling mechanisms to eliminate the influence of frequency splitting.

[0004] Compared with the magnetically coupled resonant mode system, the real eigenstate mode system has the following characteristics: 1) The system resonant frequency of the real eigenstate mode is affected by the singularity point, and the system resonant frequency can only have a real solution in the strong coupling region. The solution in the weak coupling region is a complex value, which causes the real eigenstate mode to be unable to work in the weak coupling region; 2) The output power of the real eigenstate mode is fixed, has nothing to do with the coupling condition of the system, and is only affected by the excitation voltage. However, the withstand voltage of high-frequency power switching devices is generally low, making it difficult to increase the output power of the system.

[0005] The real eigenstate MC-WPT technology has attracted much attention in recent years, but there are few related studies, which need further research. The existing research on the real eigenstate technology is summarized as follows: Regarding the problem that there is no real solution for the resonant frequency of the real eigenstate MC-WPT system in the weak coupling region outside the singularity, the current method of system electrical parameter optimization is used to obtain the influence of parameters such as coil inductance and load on the singularity through theoretical deduction, and then optimize the various electrical parameters of the system, expand the working area of ​​the strong coupling region, and improve the effective energy transfer range of the system; another method is to use other working modes in the weak coupling region outside the singularity to avoid the situation where the real eigenstate working mode is not applicable. As for the problem of fixed output power of the real eigenstate mode, it is limited by the rated withstand voltage of the high-frequency power switching device. Usually, the parameter optimization method is used to change the electrical parameter characteristics of the system itself, reduce the internal resistance of the coil itself, increase the load resistance, and improve the output power of the system under the rated voltage level.

[0006] In order to solve the problem that the real eigenstate mode in the weak coupling zone is not applicable, the parameter optimization method is often required to adjust the electrical parameter characteristics of the system. The singularity of the real eigenstate mode is related to the compensation capacitor, coil inductance, internal resistance and load resistance of the MC-WPT system. The inductance and capacitance are matched, and for the optimization of inductance, there are strict restrictions on the thickness, size and volume of the coil in certain application scenarios. The optimization of the internal resistance of the line can only be reduced to a certain extent, and the internal resistance of the device always exists. The adjustment of the load resistance often requires additional circuit devices, which not only increases the complexity of the system, but also brings additional losses. In addition, parameter optimization can only change the singularity to a certain extent and reduce the scope of the weak coupling zone, but the weak coupling zone still exists, and it still cannot solve the problem that the real eigenstate mode in the weak coupling zone cannot work.

[0007] However, when switching to other modes in the weak coupling region, the coupling regions between the different working modes are different, and the coupling regions cannot be strictly complementary. On the one hand, there may be a vacuum in the working mode, and on the other hand, additional control circuits need to be added, which makes the switching between different modes too complicated.

[0008] For the problem of fixed output power in real eigenstate mode, the parameter optimization method has limited improvement on output power. Output power is related to load resistance and line internal resistance. Therefore, optimization of load resistance also requires additional circuit components, and optimization of line internal resistance also has limited improvement.

[0009] In summary, the further development of real eigenstate modes has broad prospects, but there are still few related studies. Existing research topics are mainly used to eliminate frequency splitting, improve the energy efficiency performance in the strong coupling zone, improve the system's anti-offset characteristics and optimize the system's electrical parameters. However, whether it is to study the situation where the real eigenstate mode in the weak coupling zone outside the singularity is not applicable, or to study the situation where the output power is fixed and difficult to increase, there is currently no good solution. Existing methods make it difficult to simultaneously consider the effective energy transfer range of the real eigenstate and the problem of fixed output power. At present, there is no method that can not only improve the effective energy transfer range of the real eigenstate MC-WPT system, realize the energy transfer of the real eigenstate range in any range, but also meet the requirements of improving the system output power on the basis of fixed output power. Summary of the invention

[0010] The present invention provides a real eigenstate MC-WPT system with efficient energy transmission within an arbitrary distance range, and solves the technical problem of how to improve the effective energy transmission range of the real eigenstate MC-WPT system, realize energy transmission within an arbitrary range of real eigenstates, and also meet the requirement of improving the system output power on the basis of a fixed output power.

[0011] In order to solve the above technical problems, the present invention provides a real eigenstate MC-WPT system with efficient energy transmission within any distance range, including a transmitting circuit, a receiving circuit, a compensation circuit and a control circuit; the transmitting circuit is provided with a transmitting coil L1, and the receiving circuit is provided with a receiving coil L s1 The compensation circuit is provided with a compensation coil L2; the control circuit is used to collect the coupling mutual inductance M of the actual application scenario 1s 、M 2s and M 12 , and according to M 1s 、M 2s and M 12 , under the constraints of the optimal efficiency compensation strategy of the compensation coil, the power allocation strategy, the parameter conditions of the system resonance, the parameter setting conditions of the real eigenstate, and the zero phase angle characteristics of the real eigenstate, the control signals applied to the transmitting coil inverter and the compensation coil inverter are determined, M 1s Represents the transmitting coil L1 and the receiving coil L s1 The mutual inductance between 2s Represents the receiving coil L s1 Mutual inductance with compensation coil L2, M 12 represents the mutual inductance between the transmitting coil L1 and the compensating coil L2.

[0012] Preferably, the control signal applied by the control circuit to the transmitting coil inverter is:

[0013] The angular frequency is ω, the amplitude and phase are signal;

[0014] The control signal applied by the control circuit to the compensation coil inverter is:

[0015] The angular frequency is ω, the amplitude and phase are signal;

[0016] is the reference voltage, ω, The details are as follows:

[0017]

[0018]

[0019] Among them, the custom parameter Λ=M 1s (M 1s +αM 2s ), α represents the 1s 、M 2s 、M 12 and the current amplitude ratio between the compensation coil L2 and the transmitting coil L1 determined by the optimal efficiency compensation strategy and the optimal power allocation strategy; L s =L s1 +L s2 represents the inductance of the receiving circuit, L s2 Represents the receiving coil L s1 The series compensation lumped inductor, L1 = L2 = L s1 =L; R s =R s1 +R L represents the resistance of the receiving circuit, R L Represents the load resistance, R s1 Represents the internal resistance of the receiving coil; C = C1 = C2 = C s , C1 represents the series compensation capacitor of the transmitting coil L1, C2 represents the series compensation capacitor of the compensation coil L2, C s Represents the receiving coil L s1 Series compensation capacitor; X s =ωL s -1 / (ωC s ) represents the reactance of the receiving circuit, X2 = ωL2-1 / (ωC2) represents the reactance of the compensation circuit; R2 = R1 = R s1 =R, R1 and R2 represent the internal resistance of the transmitting coil and the compensation coil respectively; represents the transmitting coil current determined according to the zero phase angle characteristic constraint of the real eigenstate.

[0020] Preferably, the current amplitude ratio α is determined by the following steps:

[0021] According to M 1s 、M 2s 、M12 Determine the minimum compensation value of the compensation coil current amplitude ratio

[0022]

[0023] According to the optimal efficiency compensation strategy of the compensation coil L2, the optimal value of the compensation coil current amplitude ratio is determined

[0024]

[0025] According to the power allocation strategy, the current amplitude ratio of the compensation coil is determined to be α=max(α min ,α opt ), the operator max(·) is used to select α min and α opt The maximum value in .

[0026] Preferably, the parameter conditions for system resonance are:

[0027] Preferably, the compensation inductance L of the receiving coil is determined according to the parameter setting conditions of the real eigenstate. s2 =αM 12 .

[0028] Preferably, the current of the transmitting coil is determined according to the zero phase angle characteristic constraint of the real eigenstate.

[0029] Preferably, the control circuit is based on M 1s 、M 2s and M 12 , under the constraints of the optimal efficiency compensation strategy of the compensation coil, the power allocation strategy, the parameter conditions of the system resonance, the parameter setting conditions of the real eigenstate, and the zero phase angle characteristics of the real eigenstate, the control signal applied to the transmitting coil inverter and the compensation coil inverter is determined, specifically comprising the steps of:

[0030] S1. According to M 1s 、M 2s and M 12 , determine the minimum compensation value of the compensation coil current amplitude ratio

[0031]

[0032] S2. Determine the optimal value of the compensation coil current amplitude ratio based on the optimal efficiency compensation strategy of the compensation coil

[0033]

[0034] S3. According to the power allocation strategy, determine the current amplitude ratio of the compensation coil α=max(α min ,α opt), the operator max(·) is used to select α min and α opt The maximum value in ;

[0035] S4. Determine the compensation inductance L of the receiving coil according to the parameter setting conditions that meet the real eigenstate circuit. s2 =αM 12 ;

[0036] S5. According to the parameter conditions of system resonance, the working frequency of the real eigenstate system resonance is theoretically derived

[0037]

[0038] S6, with the voltage of the transmitting coil L1 As a reference voltage, determine the total power output of the system

[0039]

[0040] S7. Determine the current of the transmitting coil based on the zero phase angle characteristics of the real eigenstate

[0041] S8. Determine the amplitude and phase of the compensation coil excitation voltage:

[0042]

[0043] S9, the angular frequency, amplitude and phase applied to the transmitting coil inverter are ω. is the control signal of the reference voltage, and the angular frequency, amplitude and phase applied to the compensation coil inverter are control signal.

[0044] Preferably, the step S1 specifically comprises the steps of:

[0045] S11. In order to have a real solution for the resonant frequency of the system, The conditions are given as follows to adjust the current amplitude ratio:

[0046]

[0047] S12, determine the minimum compensation value of the compensation coil current amplitude ratio:

[0048]

[0049] In step S2, by deriving the system efficiency expression under the real eigenstate mode, the current amplitude ratio α that optimizes the system efficiency is obtained. opt , the system efficiency expression in the real eigenstate mode is as follows:

[0050]

[0051] Preferably, the step S5 specifically comprises the steps of:

[0052] S51, in Under the condition of After discarding the negative solution of ω, the four real eigenstate frequencies of the system are derived as shown in the following formula:

[0053]

[0054] Represents the quality factor of the coil;

[0055] S52, in ω 1,2 The lower operating frequency is selected from the two frequency solutions, which is shown in the following formula:

[0056]

[0057] Preferably, before step S1, the method further comprises the following steps:

[0058] S0, set the voltage of the system transmitting coil L1 is the reference voltage, set the load resistance R L , C, R, L.

[0059] The real eigenstate MC-WPT system with efficient energy transmission within any distance range provided by the present invention has the following effects:

[0060] (1) Taking the improvement of the effective energy transfer range and output power of the real eigenstate working mode as the starting point, based on the compensation effect of the active compensation coil, the system has a real number solution in the resonant frequency of the weak coupling region and improves the output power of the system. The idea and working principle of this invention are superior to the existing methods;

[0061] (2) The relationship between the system resonant frequency, output power and the current amplitude ratio between the transmitting coil and the compensation coil in the real eigenstate mode after the compensation coil is introduced is constructed, the criterion for improving the effective energy transfer range of the real eigenstate is established, and a novel optimal power allocation strategy is proposed;

[0062] (3) The designed system can realize the applicability of any coupling area of ​​the real eigenstate mode, and improve the output power of the system based on the original output power of the transmitting coil. When the position of the receiving coil changes and the coupling area changes, it is only necessary to adjust the amplitude and phase of the compensation coil. By adjusting the amplitude and phase of the compensation coil excitation voltage, changing the current amplitude ratio and changing the frequency characteristics and power characteristics of the system, the real eigenstate energy transfer range and output power can be improved without the need to optimize the parameters of the original MC-WPT system.

[0063] (4) When operating in the real eigenstate mode, the system is always in a resonant state, which can ensure a larger output power and higher transmission efficiency, improve the system's robustness and anti-offset capability, increase system stability, and the system is always in a zero phase angle (ZPA), further reducing system losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 It is a structural diagram of a real eigenstate MC-WPT system for efficient energy transmission within any distance range provided by an embodiment of the present invention;

[0065] Figure 2 It is a schematic diagram of the positions of the transmitting coil, the receiving coil, and the compensating coil provided in an embodiment of the present invention;

[0066] Figure 3 The embodiment of the present invention provides Figure 1 Equivalent circuit diagram of

[0067] Figure 4 is a control flow chart of a control circuit provided by an embodiment of the present invention;

[0068] Figure 5 is a curve diagram showing the change of the current amplitude ratio with the position of the receiving coil in the simulation provided by the embodiment of the present invention;

[0069] Figure 6 is a curve diagram showing the variation of the operating frequency with the position of the receiving coil in the simulation provided by an embodiment of the present invention;

[0070] Figure 7 is a curve diagram showing changes in system efficiency versus receiving coil position in a simulation provided by an embodiment of the present invention;

[0071] Figure 8 It is a curve diagram showing the variation of system output power with current amplitude ratio in the simulation provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0072] 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.

[0073] The embodiment of the present invention provides a real eigenstate MC-WPT system with efficient energy transmission within any distance range, such as Figure 1 As shown, in this embodiment, it includes a transmitting circuit, a receiving circuit, a compensation circuit and a control circuit. The transmitting circuit is provided with a DC power supply V D1, inverter 1, transmitting coil L1 (its internal resistance is represented by R1), the series compensation capacitor C1 of the transmitting coil L1, and the output current of inverter 1 is represented by Indicates that the output voltage is The receiving circuit is provided with a receiving coil L s1 (The internal resistance is R s1 Represents), receiving coil L s1 The series compensation lumped inductance L s2 , receiving coil L s1 The series compensation capacitor C s and load resistance R L , L s1 The current is i s The compensation circuit is equipped with a DC power supply V D2 , inverter 2, compensation coil L2 (its internal resistance is represented by R2), series compensation capacitor C2 of compensation coil L2, and the output current of inverter 2 is represented by Indicates that the output voltage is Indicates. 1s Represents the transmitting coil L1 and the receiving coil L s1 The mutual inductance between 2s Represents the receiving coil L s1 Mutual inductance with compensation coil L2, M 12 represents the mutual inductance between the transmitting coil L1 and the compensating coil L2.

[0074] like Figure 2 As shown, the transmitting coil L1 and the receiving coil L s1 The compensation coil L2 is coaxially opposite to each other.

[0075] The simplified circuit diagram of the WPT system with the compensation coil is shown in Figure 3 shown.

[0076] In order to make the system easier to analyze, it is advisable to make general assumptions about the inductance, internal resistance and compensation capacitance of the transmitting coil, receiving coil and compensation coil, as shown in the following formula:

[0077]

[0078] right Figure 3 Applying KVL to the system yields the loop equation as shown below:

[0079]

[0080] Wherein, Z1=R1+jX1 represents the impedance of the transmitting circuit, X1=ωL1-1 / (ωC1) represents the reactance of the transmitting circuit. Z2=R2+jX2 represents the impedance of the compensation circuit, X2=ωL2-1 / (ωC2) represents the reactance of the compensation circuit. s =Rs +jX s Represents the receiving circuit impedance, X s =ωL s -1 / (ωC s ) represents the reactance of the receiving circuit, L s =L s1 +L s2 Represents the inductance of the receiving circuit, R s =R s1 +R L Represents the resistance of the receiving circuit.

[0081] According to formula (2), the general expressions of the current of the receiving coil and the load power are:

[0082]

[0083] From formula (3), we can see that when In phase The maximum, at this time the load receiving power P is the maximum. Therefore, the current of the compensation coil and the transmitting coil designed in this paper must be in phase to provide the maximum power compensation for the WPT system. When the current is in phase, it is assumed that the current amplitude ratio between the compensation coil and the transmitting coil satisfies the following proportional relationship:

[0084]

[0085] Substituting equation (4) into equation (2), we get the following KVL equation:

[0086]

[0087] From formula (5), we can see that after the compensation coil is converted to the transmitting coil, the three-coil mathematical model can be equivalent to a two-coil system model. According to the circuit principle, after the load effect of the system in formula (5) is represented by the reflected impedance in the transmitting coil, the input impedance of the transmitting coil is as follows:

[0088]

[0089] Formula (6) is decomposed into real and imaginary parts as shown below:

[0090]

[0091] The custom parameter Λ=M 1s (M 1s +αM 2s ).

[0092] Formula (7) shows that the equivalent input reactance X in = 0, the system is in the eigenstate working mode, and the parameter conditions are derived as shown in the following formula:

[0093]

[0094] Formula (8) shows that when the system works in the real eigenstate mode, the self-inductance L of the receiving coil is s And the relationship between the system's resonant frequency ω and the current amplitude ratio α.

[0095] In order to achieve high energy efficiency transmission in wireless power transmission system, the quality factor of the coil Generally the setting is large. Under the condition of , combined with the formula of the system resonant frequency of formula (8), after discarding the negative solution of ω, the real eigenstate frequency of the system is derived as shown in the following formula:

[0096]

[0097] According to the condition of the system resonant frequency in equation (9), in order to make the system resonant frequency have a real solution, it is necessary to satisfy Based on the conditions, the compensation criterion for adjusting the current amplitude ratio and improving the effective energy transfer range is given as shown in the following formula.

[0098]

[0099] Formula (10) shows that by adjusting the current of the compensation coil so that the current amplitude ratio α between the compensation coil and the transmitting coil always satisfies the condition of formula (10), the real eigenstate mode can have a real solution under any coupling condition.

[0100] From formula (10), it can be seen that the minimum compensation current amplitude ratio of the compensation coil is as follows:

[0101]

[0102] The system power and efficiency formulas in real eigenstate mode are as follows:

[0103]

[0104] in is the constant output power of the transmitting coil.

[0105] Formula (12) shows that the output power of the real eigenstate wireless power transmission system with compensation can be decoupled into the output power P1 of the transmitting coil and the compensation power P1αM of the compensation coil. 2s / M 1s The compensation coil can improve the fixed output power of the real eigenstate system, and the output power of the compensation coil can be adjusted by changing the current amplitude ratio α between the compensation coil and the transmitting coil.

[0106] By taking the derivative of the current amplitude ratio α of the efficiency expression of equation (12), we can obtain the current amplitude ratio that optimizes the system efficiency as shown in the following equation:

[0107]

[0108] Formula (13) shows that by adjusting the current of the compensation coil, the efficiency of the system can be improved by adjusting the current between the compensation coil and the transmitting coil.

[0109] Therefore, this embodiment, on the basis of satisfying the real solution of the real eigenstate working mode of formula (11), combines the strategy of optimal efficiency of formula (13) to propose a novel optimal power compensation strategy, the current amplitude ratio of the compensation coil of this strategy is shown in the following formula:

[0110] α=max(α min ,α opt ) (14)

[0111] The operator max(·) is used to select α min and α opt The maximum value in .

[0112] After obtaining the current amplitude ratio α according to the optimal power allocation strategy of formula (14), combined with the parameter conditions of the receiving coil self-inductance of formula (8), the compensation inductance of the receiving coil is obtained as shown in the following formula:

[0113] L s2 =αM 12 (15)

[0114] At this time, the resonant frequency of the system is as shown in formula (9): 0,1,2,3 , because the higher the frequency of high-frequency power switching devices, the greater the switching loss of the system and the more unstable the device performance. 1,2 The lower operating frequency is selected from the two frequency solutions, which is shown in the following formula:

[0115]

[0116] According to the optimal power allocation strategy of formula (14) and the power allocation relationship between the transmitting coil and the compensation coil of formula (12), formula (12) and formula (14) are combined to obtain the voltage of the transmitting coil L1. As a reference voltage, determine the total power P output by the system.

[0117]

[0118] In the real eigenstate mode, X in =0, the equivalent impedance of the transmitting coil backward is as follows:

[0119] Zeq =R+R s (18)

[0120] According to formula (18), the transmitting coil is at zero phase angle (ZPA), and the impedance characteristic is purely resistive. At this time, the current of the transmitting coil is as follows:

[0121]

[0122] Formula (19) shows that when the resistance remains unchanged, the voltage of the transmitting coil is Under certain conditions, the current of the transmitting coil does not change with the change of coupling conditions.

[0123] In order to satisfy the current amplitude ratio of the optimal power allocation strategy in equation (14), combined with the current relationship between the transmitting coil and the compensation coil in equation (12), equations (12) and (14) are substituted into equation (2) to derive the control voltage of the compensation coil as shown below:

[0124]

[0125] Therefore, the voltage of the transmitting coil As the reference voltage, the control voltage is applied to the compensation coil After that, the current amplitude ratio α of the optimal power allocation strategy is realized. This not only ensures that the system is always in the effective energy transfer range of the real eigenstate, but also improves the power output of the system.

[0126] Based on the above analysis, if Figure 4 As shown, the control circuit of the embodiment of the present invention is based on M 1s 、M 2s and M 12 , under the constraints of the optimal efficiency compensation strategy of the compensation coil, the power allocation strategy, the parameter conditions of the system resonance, the parameter setting conditions of the real eigenstate, and the zero phase angle characteristics of the real eigenstate, the control signal applied to the transmitting coil inverter and the compensation coil inverter is determined, specifically comprising the steps of:

[0127] S0, set the voltage of the system transmitting coil L1 is the reference voltage, set the load resistance R L , C, R, L, and collect M 1s 、M 2s and M 12 ;

[0128] S1. According to M 1s 、M 2s and M 12 , determine the minimum compensation value of the compensation coil current amplitude ratio

[0129]

[0130] S2. Determine the optimal value of the compensation coil current amplitude ratio based on the optimal efficiency compensation strategy of the compensation coil

[0131]

[0132] S3. According to the power allocation strategy, determine the current amplitude ratio of the compensation coil α=max(α min ,α opt ), the operator max(·) is used to select α min and α opt The maximum value in ;

[0133] S4. Determine the compensation inductance L of the receiving coil according to the parameter setting conditions that meet the real eigenstate circuit. s2 =αM 12 ;

[0134] S5. According to the parameter conditions of system resonance, the working frequency of the real eigenstate system resonance is theoretically derived

[0135]

[0136] S6, with the voltage of the transmitting coil L1 As a reference voltage, determine the total power output of the system

[0137]

[0138] S7. Determine the current of the transmitting coil based on the zero phase angle characteristics of the real eigenstate

[0139] S8. Determine the amplitude and phase of the compensation coil excitation voltage:

[0140]

[0141] S9, the angular frequency, amplitude and phase applied to the transmitting coil inverter are ω. is the control signal of the reference voltage, and the angular frequency, amplitude and phase applied to the compensation coil inverter are control signal.

[0142] Then, the system outputs the increased total power P, and the system operates in the real eigenstate effective energy transfer range.

[0143] Wherein, step S1 specifically includes the steps of:

[0144] S11. In order to have a real solution for the resonant frequency of the system, conditions, according to Adjust the current amplitude ratio;

[0145] S12, determine the minimum compensation value of the compensation coil current amplitude ratio

[0146] Step S5 specifically includes the following steps:

[0147] S51, in Under the condition of After discarding the negative solutions, the four real eigenstate frequencies ω of the system are derived: 0,1,2,3 ;

[0148] S52, in ω 1,2 The lower operating frequency is selected among the two frequency solutions.

[0149] The compensation coil proposed by the present invention has the following advantages:

[0150] 1) The active compensation of the compensation coil can realize the effective energy transfer of the real eigenstate mode in any range, and no mode switching is required in the entire area, and it is completely in the real eigenstate working mode;

[0151] 2) The active compensation of the compensation coil can achieve parallel output of the compensation coil power and improve the output power of the system;

[0152] 3) The introduction of the compensation coil does not destroy the system resonance, and the system's transmitting coil can still achieve zero phase angle (ZPA) operation, further reducing the system's loss and improving the system's energy efficiency performance;

[0153] 4) On the basis of meeting the effective energy transmission range, the compensation coil improves the output power of the system with optimal power distribution.

[0154] The real eigenstate MC-WPT system with efficient energy transmission within any distance range provided by the embodiment of the present invention has the following effects:

[0155] (1) Taking the improvement of the effective energy transfer range and output power of the real eigenstate working mode as the starting point, based on the compensation effect of the active compensation coil, the problem of fixed output power of the real eigenstate system is made up, so that the system has a real number solution in the weak coupling region resonant frequency and improves the output power of the system. The idea and working principle of the invention are superior to the existing methods;

[0156] (2) The relationship between the system resonant frequency, output power and the current amplitude ratio between the transmitting coil and the compensation coil in the real eigenstate mode after the compensation coil is introduced is constructed, the criterion for improving the effective energy transfer range of the real eigenstate is established, and a novel optimal power allocation strategy is proposed;

[0157] (3) The designed system can realize the applicability of any coupling area of ​​the real eigenstate mode, and improve the output power of the system based on the original output power of the transmitting coil. When the position of the receiving coil changes and the coupling area changes, it is only necessary to adjust the amplitude and phase of the compensation coil. By adjusting the amplitude and phase of the compensation coil excitation voltage, changing the current amplitude ratio and changing the frequency characteristics and power characteristics of the system, the real eigenstate energy transfer range and output power can be improved without the need to optimize the parameters of the original MC-WPT system.

[0158] (4) When operating in the real eigenstate mode, the system is always in a resonant state, which can ensure a larger output power and higher transmission efficiency, improve the system's robustness and anti-offset capability, increase system stability, and the system is always in a zero phase angle (ZPA), further reducing system losses.

[0159] The effect of the present invention is verified below.

[0160] For the above conclusions, this example uses MATLAB numerical simulation to verify the real eigenstate wireless power transmission system with compensation coils. The simulation parameters are shown in Table 1.

[0161] Table 1 Simulation parameter settings

[0162]

[0163] By changing the position of the receiving coil so that the receiving coil is in different coupling areas, the curves of the current amplitude ratio, the system resonant frequency, and the overall efficiency of the system changing with the position of the receiving coil can be obtained as shown in the figure below. Figure 5 , Figure 6 , Figure 7 As shown, curve α = 0 means the compensation coil is not working, curve α min The compensation coil works with the minimum compensation current amplitude ratio within the energy transfer range. Curve α opt An efficiency-optimal current amplitude ratio is adopted for the compensation coil.

[0164] according to Figure 5 The simulation results show that: as shown by the curve α = 0, the compensation coil is not working; as shown by the curve α min As shown in the figure, in the strong coupling area, the compensation coil does not need to work. In the weak coupling area, in order to meet the minimum compensation of the effective energy transfer range of the system, the current amplitude ratio begins to increase; as shown in the curve α opt As shown, to achieve the most efficient power distribution, the current amplitude ratio varies with the position of the receiving coil in both the strong coupling region and the weak coupling region.

[0165] according to Figure 6The simulation results in Fig. 2 show that: as shown by the curve α = 0, when the compensation coil is not working, the system resonant frequency can only have a real solution in the strong coupling region, and there is no real solution in the weak coupling region; as shown by the curve α min When the compensation coil shown in the figure adopts the minimum compensation current amplitude ratio in the energy transfer range, the system resonant frequency in the weak coupling region appears a solution and coincides; as shown in curve α opt As shown in the figure, when the compensation coil adopts the current amplitude ratio with the best efficiency, due to the current amplitude ratio α opt >α min , at this time, the compensation effect of the compensation coil is stronger, and the resonant frequency of the system is split into two independent real solutions. That is, the system can adjust the current amplitude ratio of the compensation coil to achieve a real solution of the real eigenstate mode in the weak coupling region system resonant frequency, thereby improving the effective energy transfer range of the real eigenstate mode.

[0166] according to Figure 7 The simulation results in Fig. 2 show that: as shown by the curve α = 0, when the compensation coil is not working, the system efficiency is constant in the strong coupling region; as shown by the curve α min As shown in Fig. 1, when the compensation coil adopts the minimum compensation current amplitude ratio in the energy transfer range, the compensation coil starts to work in the weak coupling area, which improves the efficiency of the weak coupling area system. opt When the compensation coil adopts the current amplitude ratio with the best efficiency, the compensation coil can improve the system efficiency the most. That is, the system adopts the optimal power allocation strategy α=max(α min ,α opt ), the current amplitude ratio should be α=α opt , a power allocation strategy can be implemented to satisfy the real eigenstate operating frequency and maximize the system efficiency.

[0167] According to the optimal power allocation strategy, the current amplitude ratio is α = α opt By changing the position of the receiving coil, we can get the curve of output power changing with the position of the receiving coil. Figure 8 As shown. Among them, curve P1 is the power output of the transmitting coil, curve P1αM 2s / M 1s is the compensation power output by the compensation coil, and curve P is the total output power of the system.

[0168] according to Figure 8 From the simulation results, it can be seen that, as shown by curve P1, the output power of the transmitting coil is fixed and does not change with the position of the receiving coil. 2s / M 1sAs shown in the figure, the power output of the compensation coil changes with the current amplitude ratio, and the power output of the compensation system is compensated in parallel. As shown in the curve P, after the total output power of the system is compensated, the power output capacity is greatly improved. That is, the system can achieve the fixed power output of the real eigenstate mode, and improve the overall power output capacity of the system through the power compensation of the compensation coil.

[0169] In summary, the simulation results are consistent with the theoretical derivation conclusions. By controlling the amplitude and phase of the voltage of the compensation coil, the current of the compensation coil can be at the current amplitude ratio for optimal power compensation, which can realize energy transfer in any range of the real eigenstate system and improve the constant power output of the real eigenstate system.

[0170] 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 real eigenstate MC-WPT system with efficient energy transmission within any distance range, characterized by: It includes a transmitting circuit, a receiving circuit, a compensation circuit and a control circuit; the transmitting circuit is provided with a transmitting coil L1, and the receiving circuit is provided with a receiving coil L s1 The compensation circuit is provided with a compensation coil L2; the control circuit is used to collect the coupling mutual inductance M of the actual application scenario 1s 、M 2s and M 12 , and according to M 1s 、M 2s and M 12 , under the constraints of the optimal efficiency compensation strategy of the compensation coil, the power allocation strategy, the parameter conditions of the system resonance, the parameter setting conditions of the real eigenstate, and the zero phase angle characteristics of the real eigenstate, the control signals applied to the transmitting coil inverter and the compensation coil inverter are determined, M 1s Represents the transmitting coil L1 and the receiving coil L s1 The mutual inductance between 2s Represents the receiving coil L s1 Mutual inductance with compensation coil L2, M 12 represents the mutual inductance between the transmitting coil L1 and the compensating coil L2; The control circuit is based on M 1s 、M 2s and M 12 , under the constraints of the optimal efficiency compensation strategy of the compensation coil, the power allocation strategy, the parameter conditions of the system resonance, the parameter setting conditions of the real eigenstate, and the zero phase angle characteristics of the real eigenstate, the control signal applied to the transmitting coil inverter and the compensation coil inverter is determined, specifically comprising the steps of: S1. According to M 1s 、M 2s and M 12 , determine the minimum compensation value of the compensation coil current amplitude ratio S2. Determine the optimal value of the compensation coil current amplitude ratio based on the optimal efficiency compensation strategy of the compensation coil S3. According to the power allocation strategy, determine the current amplitude ratio of the compensation coil α=max(α min ,α opt ), the operator max(·) selects the maximum value between αmin and αopt; S4. Determine the compensation inductance L of the receiving coil according to the parameter setting conditions that meet the real eigenstate circuit. s2 =αM 12 ; S5. According to the parameter conditions of system resonance, the working frequency of the real eigenstate system resonance is theoretically derived S6, with the voltage of the transmitting coil L1 As a reference voltage, determine the total power output of the system S7. Determine the current of the transmitting coil based on the zero phase angle characteristics of the real eigenstate S8. Determine the amplitude and phase of the compensation coil excitation voltage: S9, the angular frequency applied to the transmitting coil inverter is ω, the amplitude and phase are The control signal applied to the compensation coil inverter has an angular frequency of ω, an amplitude and a phase of The control signal of Among them, the custom parameter Λ=M 1s (M 1s +αM 2s ), L s =L s1 +L s2 represents the inductance of the receiving circuit, L s2 Represents the receiving coil L s1 The series compensation lumped inductor, L1 = L2 = L s1 =L; R s =R s1 +R L represents the resistance of the receiving circuit, R L Represents the load resistance, R s1 Indicates the internal resistance of the receiving coil; C=C1=C2=C s , C1 represents the series compensation capacitor of the transmitting coil L1, C2 represents the series compensation capacitor of the compensation coil L2, and Cs represents the series compensation capacitor of the receiving coil Ls1; X s =ωL s -1 / (ωC s ) represents the reactance of the receiving circuit, X2 = ωL2-1 / (ωC2) represents the reactance of the compensation circuit; R2 = R1 = R s1 =R, R1 and R2 represent the internal resistance of the transmitting coil and the compensation coil respectively; The step S1 specifically includes the following steps: S11. In order to have a real solution for the resonant frequency of the system, The conditions are given as follows to adjust the current amplitude ratio: S12, determine the minimum compensation value of the compensation coil current amplitude ratio: In step S2, by deriving the system efficiency expression under the real eigenstate mode, the current amplitude ratio α that optimizes the system efficiency is obtained. opt , the system efficiency expression in the real eigenstate mode is as follows: The step S5 specifically includes the following steps: S51, in Under the condition of After discarding the negative solution of ω, the four real eigenstate frequencies of the system are derived as shown in the following formula: Represents the quality factor of the coil; S52, in ω 1,2 The lower operating frequency is selected in the two frequency solutions, which is shown in the following formula: Before step S1, the method further includes the following steps: S0, set the voltage of the system transmitting coil L1 is the reference voltage, set the load resistance R L , C, R, L.

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