Wireless power transmission system with modal switching and parameter optimization design method

Abstract

The application discloses a wireless power transmission system with mode switching and a parameter optimization design method, and relates to the technical field of wireless power transmission. The system is designed with a series hybrid compensation topology network, a quantitative relationship between the system and the working frequency is established, the working mode is controlled by taking the working frequency as a variable, and all system parameters are established. Since the quantitative relationship between the output current and the system parameters is established, the hybrid topology has a load-independent output characteristic, and the system parameters can be directly solved according to the constraint condition. In addition, a parameter optimization design method is established based on the system, which includes establishing a mutual inductance fluctuation retention ratio, taking the combined current fluctuation ratio as a constraint, and taking the maximum mutual inductance fluctuation retention ratio as an optimization target, so that the anti-deviation capability of the system is improved, the parameter design is simplified, and the high-efficiency output of the constant-current mode is ensured. The method can be popularized to other hybrid topologies, is suitable for different asymmetric magnetic coupling mechanisms, and realizes the maximization of multi-directional misalignment tolerance.

Description

Technical Field

[0001] This invention relates to the field of wireless power transmission technology, and in particular to a wireless power transmission system with mode switching and a parameter optimization design method. Background Technology

[0002] Wireless power transfer (WPT) is a technology that utilizes spatial electromagnetic variations to achieve contactless power transmission. This technology overcomes the limitations of traditional wired and contact-based power transmission, attracting increasing attention from researchers. Furthermore, WPT continues to evolve towards higher efficiency, higher power, and greater applicability. However, the transmission distance significantly impacts system power and efficiency; therefore, the widespread application of WPT technology lies in utilizing the near-field effect of electromagnetic fields (EMF) to achieve short-distance power transmission.

[0003] Based on the transmission channel, near-field power transfer (WPT) technologies utilizing electromagnetic fields can be divided into two categories. Capacitive power transfer (CCPT) is a representative example of electric field-coupled WPT technology, while inductive wireless power transfer (IPT) is a representative example of magnetic field-coupled WPT technology. Compared to magnetic field-coupled technology, electric field-coupled technology is limited by its finite transmission distance, while magnetic field-coupled transmission channels exhibit a wider transmission range in near-field environments. Currently, this technology has been applied in fields such as drones, portable electronic devices, implantable medical devices, and electric vehicles. However, in practical applications of IPT systems, misalignment of the receiving coil will lead to a sharp decrease in the system's output efficiency and reliability. Therefore, improving misalignment tolerance is one of the key issues in IPT technology research.

[0004] To address the output fluctuation problem of IPT systems, current research focuses on hybrid topologies, parameter optimization, control strategies, and magnetic coupling mechanisms. Hybrid topologies include series hybrid compensation structures, variable inductor topologies, and clamping circuits. Reconfigurable topologies ensure stable output under weak coupling conditions. However, the sensitivity of compensation parameters in hybrid topologies can still lead to output characteristic drift, and achieving ZVS operation of the inverter switches is difficult. Parameter optimization methods, such as particle swarm optimization, multi-objective optimization, and frequency tuning strategies, achieve high-efficiency output under coupling and load fluctuations. However, the improvement in misalignment tolerance through parameter optimization alone is often limited. Control strategies include hybrid control combining phase-shift modulation and frequency tracking, and dual-loop decoupling control. However, the increased system control complexity leads to a sharp decline in system reliability and stability over a wide coil offset range. In terms of magnetic coupling mechanism design, increasing the size difference between the receiving and transmitting coils suppresses mutual inductance fluctuations caused by lateral offset, and constructing an intermediate coil improves the system misalignment tolerance. Nevertheless, traditional coupling mechanisms have limited resistance to offset, and the addition of an intermediate coil increases the size of the coupler, which increases system losses and reduces system transmission efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a wireless power transmission system with mode switching and a parameter optimization design method, aiming to solve or improve at least one of the above-mentioned technical problems.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] A wireless power transfer system with mode switching includes: a series hybrid compensation topology network consisting of a full-bridge inverter circuit, a primary-side compensation network, a coupling coil, a secondary-side compensation network, and a rectifier filter circuit; wherein the primary-side compensation network includes: a primary-side series compensation capacitor C. p1 Primary circuit compensation capacitor C p2 Primary branch compensation capacitor C p0 and compensation inductor L p0 ; wherein, the primary side branch compensation capacitor C p0 and the compensation inductor L p0 Connect in parallel to form the original side branch;

[0008] The input terminal of the full-bridge inverter circuit is connected to the DC voltage source U. D The primary-side series compensation capacitor C is connected. p1 One end is connected to the output terminal A of the full-bridge inverter circuit, and the output terminal B of the full-bridge inverter circuit is connected to the primary-side circuit compensation capacitor C. p2 Connected to one end of the primary side branch; the primary side series compensation capacitor C p1 The primary circuit compensation capacitor C p2 The other end of the primary branch is connected to the primary input terminal of the coupling coil; the secondary output terminal of the coupling coil is connected to the input terminal of the secondary compensation network, the output terminal of the secondary compensation network is connected to the input terminal of the rectifier-filter circuit, and the output terminal of the rectifier-filter circuit is connected to the battery load R. L connect.

[0009] Optionally, the coupling coil specifically includes: a primary-side first transmitting coil L p1 Primary side second transmitting coil L p2 Secondary side first receiving coil L s1 and the second receiving coil L on the secondary side s2 ;

[0010] The primary side first transmitting coil L p1 and the second transmitting coil L on the primary side p2 The two are connected in series in the same direction, and the first receiving coil L on the secondary side is... s1 and the second receiving coil L on the secondary side s2They are connected in the same direction and electromagnetically coupled between the two coils on the primary side and the two coils on the secondary side;

[0011] Wherein, the primary side first transmitting coil L p1 One end is connected in series with the primary side to a compensation capacitor C p1 Connection, the primary side first transmitting coil L p1 The other end is connected to the primary side branch and the primary side second transmitting coil L, respectively. p2 One end is connected to the primary side second transmitting coil L. p2 The other end is connected to the primary side loop compensation capacitor C. p2 Connection; the secondary side first receiving coil L s1 and the second receiving coil L on the secondary side s2 All are connected to the secondary side compensation network.

[0012] Optionally, the secondary-side compensation network specifically includes: a secondary-side series compensation capacitor C. s1 Secondary circuit compensation capacitor C s2 Secondary branch series compensation capacitor C x Parallel compensation capacitor C of secondary branch s0 and compensation inductor L s0 The secondary branch parallel compensation capacitor C s0 and the compensation inductor L s0 Parallel connections form secondary side branches;

[0013] The secondary-side series compensation capacitor C s1 One end is connected to the secondary side first receiving coil L s1 One end is connected, and the other end is connected to the contact C of the rectifier and filter circuit; the secondary side first receiving coil L s1 The other end is connected to the secondary side second receiving coil L. s2 One end of the secondary branch is connected in series with a compensation capacitor C x Connection; the secondary side branch series compensation capacitor C x The other end is connected to one end of the secondary branch; the secondary second receiving coil L s2 The other end is connected to the secondary circuit compensation capacitor C. s2 One end is connected; the secondary circuit compensation capacitor C s2 The other end of the circuit and the other end of the secondary branch are both connected to the contact D of the rectifier filter circuit.

[0014] Optionally, when the operating frequency of the wireless power transmission system is f1, the operating mode 1 of the wireless power transmission system is:

[0015] The primary-side series compensation capacitor C in the primary-side compensation network p1Primary branch compensation capacitor C p0 Compensating inductor L p0 and the primary side of the first transmitting coil L in the coupling coil p1 This constitutes a series resonant network; the primary-side loop compensation capacitor C in the primary-side compensation network p2 Primary branch compensation capacitor C p0 Compensating inductor L p0 and the primary side of the second transmitting coil L in the coupling coil p2 A series resonant network is formed; the secondary-side series compensation capacitor C in the secondary-side compensation network s1 Secondary branch series compensation capacitor C x Parallel compensation capacitor C of secondary branch s0 Compensating inductor L s0 and the secondary side of the first receiving coil L in the coupling coil s1 This forms a series resonant network; the secondary circuit compensation capacitor C s2 Secondary branch series compensation capacitor C x Parallel compensation capacitor C of secondary branch s0 and compensation inductor L s0 and the secondary receiving coil L in the coupling coil s2 This forms a series resonant network.

[0016] Optionally, when the operating frequency of the wireless power transmission system is f2, the operating mode 2 of the wireless power transmission system is:

[0017] The primary-side series compensation capacitor C in the primary-side compensation network p1 Primary circuit compensation capacitor C p2 and the primary side of the first transmitting coil L in the coupling coil p1 Primary side second transmitting coil L p2 A series resonant network is formed; the secondary-side series compensation capacitor C in the secondary-side compensation network s1 Secondary circuit compensation capacitor C s2 and the secondary side of the first receiving coil L in the coupling coil s1 Secondary receiving coil L s2 This forms a series detuned network.

[0018] This invention also provides a parameter optimization design method for a wireless power transfer system with mode switching, based on the system described above, comprising:

[0019] Step 1: Set the DC input voltage U according to the operating requirements. D Rated output current I0, battery load R L The system output current fluctuation ratio δ and the system operating frequency f1 under operating mode 1;

[0020] Step 2: Based on the resonance states of the primary and secondary side compensation networks under operating mode 1 and operating mode 2, obtain the constant current equation of the wireless power transfer system and the quantitative relationship between the compensation parameters.

[0021] Step 3: Based on the design requirements of the coupling coil in the wireless power transmission system, obtain the primary side first transmitting coil L using finite element simulation software. p1 Primary side second transmitting coil L p2 Secondary side first receiving coil L s1 and the second receiving coil L on the secondary side s2 The self-inductance value and mutual inductance value under different offset states were obtained, and the relationship between the main coupled mutual inductances M1 and M2 was analyzed using curve fitting.

[0022] Step 4: Define the mutual inductance holding ratio λ, and calculate the output current holding ratio relationship under working mode 1, the system operating frequency f2 and the output current holding ratio relationship under working mode 2 respectively, based on the constant current equation of the wireless charging system under working mode 1 and working mode 2, as well as the set system output current fluctuation ratio δ and system operating frequency f1 under working mode 1.

[0023] Step 5: Based on the quantitative relationship between the primary and secondary side compensation parameters under working mode 1 and working mode 2, and the optimized value of the mutual inductance retention ratio under working mode 1 and working mode 2, complete the tuning of the compensation element parameters.

[0024] Optionally, the system output current fluctuation ratio δ in step one is defined as follows:

[0025]

[0026] Among them, I Omax I represents the maximum allowable current for a wireless power transfer system. Omin This indicates the minimum current that a wireless power transmission system is allowed to transmit, and the following relationship is specified:

[0027]

[0028] Where I0 represents the rated output current.

[0029] Optionally, step two specifically includes:

[0030] Calculate the constant current equation of the wireless power transfer system in operating mode 1:

[0031]

[0032] Where A = L peq / ω1C seqB = ω1, where ω1 is the operating angular frequency of the system when the operating frequency is f1, i.e., ω1 = 2πf1, U in L is the output voltage of the full-bridge inverter circuit. peq The primary branch compensation capacitor C p0 and compensation inductor L p0 The equivalent inductance value, C seq The secondary branch is connected in series with a compensation capacitor C. x Parallel compensation capacitor C of secondary branch s0 and compensation inductor L s0 The equivalent capacitance value, M1 represents the primary side first transmitting coil L p1 and the second-side first receiving coil L s1 The mutual inductance value, M2 represents the primary side second transmitting coil L p2 and the second receiving coil L on the secondary side s2 The mutual inductance value;

[0033] Calculate the constant current equation of the wireless power transfer system in operating mode 2:

[0034]

[0035] Where ω2 is the operating angular frequency of the system when the operating frequency is f2, i.e., ω2=2πf2;

[0036] The following relationship exists between the compensation parameters of the wireless power transfer system in operating mode 1:

[0037]

[0038] Among them, C p1 C represents the capacitance value of the primary-side series compensation capacitor. p2 C represents the capacitance value of the primary loop compensation capacitor. p0 L represents the capacitance value of the primary branch compensation capacitor. p0 C represents the inductance value of the primary branch compensation inductor. s1 C represents the capacitance value of the secondary-side series compensation capacitor. s2 C represents the capacitance value of the secondary circuit compensation capacitor. x C represents the capacitance value of the series compensation capacitor in the secondary branch. s0 L represents the capacitance value of the parallel compensation capacitor in the secondary branch. s0 L represents the inductance value of the parallel compensation inductor in the secondary branch. p1 L represents the inductance value of the first transmitting coil on the primary side. p2 L represents the inductance value of the second transmitting coil on the primary side. s1 L represents the inductance value of the first receiving coil on the secondary side. s2 This indicates the inductance value of the second receiving coil on the secondary side;

[0039] The following relationship exists between the compensation parameters of the wireless power transfer system in operating mode 2:

[0040]

[0041] Among them, C p1 C represents the capacitance value of the primary-side series compensation capacitor. p2 C represents the capacitance value of the primary loop compensation capacitor. p0 L represents the capacitance value of the primary branch compensation capacitor. p0 C represents the inductance value of the primary branch compensation inductor. s1 C represents the capacitance value of the secondary-side series compensation capacitor. s2 C represents the capacitance value of the secondary circuit compensation capacitor. x C represents the capacitance value of the series compensation capacitor in the secondary branch. s0 L represents the capacitance value of the parallel compensation capacitor in the secondary branch. s0 L represents the inductance value of the parallel compensation inductor in the secondary branch. p1 L represents the inductance value of the first transmitting coil on the primary side. p2 L represents the inductance value of the second transmitting coil on the primary side. s1 L represents the inductance value of the first receiving coil on the secondary side. s2 This indicates the inductance value of the second receiving coil on the secondary side.

[0042] Optionally, the definition of the mutual inductance retention ratio λ in step four is as follows:

[0043]

[0044] Among them, M min M0 represents the minimum mutual inductance value of the coupling mechanism within the range of output current fluctuation ratio δ, and M0 represents the main coupling mutual inductance when the coupling mechanism is aligned.

[0045] The definition of the system output current holding ratio Δ is as follows:

[0046]

[0047] Among them, I O I0 represents the output current of the wireless power transfer system, and I0 represents the rated output current of the wireless power transfer system when the coupling mechanism is aligned.

[0048] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0049] This invention discloses a wireless power transfer system with mode switching and a parameter optimization design method. The system includes designing a series hybrid compensation topology network, establishing a quantitative relationship between the network and the system's operating frequency, controlling the operating mode using the operating frequency as a variable, and constructing all system parameters. Because a quantitative relationship between the output current and system parameters is established, the hybrid topology possesses load-independent output characteristics, and the system parameters can be directly solved according to constraints. Furthermore, a parameter optimization design method is constructed based on this system, including establishing the mutual inductance fluctuation retention ratio, using the joint current fluctuation ratio as a constraint, and taking the maximum mutual inductance fluctuation retention ratio as the optimization objective. This improves the system's anti-offset capability, simplifies parameter design, and ensures efficient output in constant current mode. This method can be extended to other hybrid topologies, adapting to different asymmetric magnetic coupling mechanisms, and maximizing multi-directional misalignment tolerance. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0051] Figure 1 This is a schematic diagram of the main circuit architecture of the mode-switching wireless power transmission system in this embodiment;

[0052] Figure 2 This is the equivalent circuit diagram of the system in operating mode 1 in this embodiment;

[0053] Figure 3 This is the equivalent circuit diagram of the system in operating mode 2 in this embodiment;

[0054] Figure 4 This is a flowchart illustrating the steps of the wireless power transmission system parameter design method in this embodiment;

[0055] Figure 5 This is a schematic diagram of the system output current-coupling mutual inductance curve under operating mode 1 in this embodiment;

[0056] Figure 6 This is a schematic diagram of the system output current-coupling mutual inductance curve under operating mode 2 in this embodiment. Detailed Implementation

[0057] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] The purpose of this invention is to provide a wireless power transmission system with mode switching and a parameter optimization design method, aiming to solve or improve at least one of the above-mentioned technical problems.

[0059] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0060] like Figure 1 As shown, the present invention provides a wireless power transmission system with mode switching, including: a full-bridge inverter circuit, a primary-side compensation network, a coupling coil, a secondary-side compensation network, and a rectifier filter circuit.

[0061] The input terminal of the full-bridge inverter circuit is connected to a DC voltage source U. D The output terminal is connected to the input terminal of the primary-side compensation network, the output terminal of the primary-side compensation network is connected to the primary-side input terminal of the coupling coil, the secondary-side output terminal of the coupling coil is connected to the input terminal of the secondary-side compensation network, and the output terminal of the secondary-side compensation network is connected to the input terminal of the rectifier and filter circuit; the output terminal of the rectifier and filter circuit is connected to the battery load R. L .

[0062] The primary-side compensation network includes a primary-side series compensation capacitor C. p1 Primary circuit compensation capacitor C p2 Primary branch compensation capacitor C p0 and compensation inductor L p0 ;

[0063] The coupling coil includes the primary side first transmitting coil L p1 Primary side second transmitting coil L p2 and the second-side first receiving coil L s1 Secondary receiving coil L s2 ;

[0064] The secondary-side compensation network includes a secondary-side series compensation capacitor C. s1 Secondary circuit compensation capacitor C s2 Secondary branch series compensation capacitor C x Parallel compensation capacitor C of secondary branch s0 and compensation inductor L s0 .

[0065] In the original edge compensation network:

[0066] Primary-side series compensation capacitor C p1 One end is connected to one output terminal of the full-bridge inverter circuit, and the other end is connected to the first transmitting coil L on the primary side. p1 One end;

[0067] Primary circuit compensation capacitor C p2 One end is connected to the other output terminal of the full-bridge inverter circuit, and the primary branch compensation capacitor C. p0 One end, compensating inductor L p0 One end, the primary circuit compensation capacitor C p2 The other end is connected to the primary side second transmitting coil L p2 One end;

[0068] Primary branch compensation capacitor C p0 and compensation inductor L p0 One end is connected to the full-bridge inverter circuit and the primary-side circuit compensation capacitor C. p2 The connected end is the primary branch compensation capacitor C. p0 and compensation inductor L p0 The other end is connected to the primary side first transmitting coil L p1 and the second transmitting coil L on the primary side p2 The connected end.

[0069] In the secondary side compensation network:

[0070] Secondary series compensation capacitor C s1 One end is connected to one input terminal of the rectifier filter circuit, and the other end is connected to the first transmitting coil L on the secondary side. s1 One end;

[0071] Secondary circuit compensation capacitor C s2 One end is connected to the other input terminal of the rectifier filter circuit, and a compensation capacitor C is connected in parallel to the secondary branch. s0 One end, compensating inductor L s0 One end, secondary circuit compensation capacitor C s2 The other end is connected to the secondary side second transmitting coil L s2 One end;

[0072] Parallel compensation capacitor C of secondary branch s0 and compensation inductor L s0 One end is connected to the rectifier filter circuit and the secondary circuit compensation capacitor C. s2 At one end, a compensation capacitor C is connected in parallel to the secondary branch. s0 and compensation inductor L s0 The other end is connected to the secondary branch series compensation capacitor C. x One end.

[0073] Secondary branch series compensation capacitor Cx One end is connected to the secondary branch parallel compensation capacitor C s0 and compensation inductor L s0 At one end, the secondary branch is connected in series with a compensation capacitor C. x The other end is connected to the secondary side first transmitting coil L s1 and the second transmitting coil L on the secondary side s2 The connected end.

[0074] like Figure 2 and Figure 3 As shown, by controlling the operating frequency of the wireless power transmission system, the system can enter two operating modes, which correspond to different magnetic coupling mechanism offset methods, namely operating mode 1 and operating mode 2.

[0075] Furthermore, M is designed using a coupler. p M S Approaching zero, forming self-decoupling; through coupler design, M is... 12 and M 21 Approximately zero, constituting cross-decoupling.

[0076] like Figure 2 As shown, when the wireless power transfer system operates at frequency f1, i.e., operating mode 1:

[0077] The primary-side series compensation capacitor C in the primary-side compensation network p1 Primary branch compensation capacitor C p0 and compensation inductor L p0 The primary side of the coupling coil, first transmitting coil L p1 This constitutes a series resonant network; the primary-side loop compensation capacitor C in the primary-side compensation network p2 Primary branch compensation capacitor C p0 and compensation inductor L p0 The primary side of the coupling coil, the second transmitting coil L p2 A series resonant network is formed; the secondary-side compensation network includes a secondary-side series compensation capacitor Cs1, a secondary-side branch series compensation capacitor Cx, a secondary-side branch parallel compensation capacitor Cs0, a compensation inductor Ls0, and the secondary-side first receiving coil Ls1 in the coupling coil, forming a series resonant network; the secondary-side circuit compensation capacitor Cs2, a secondary-side branch series compensation capacitor Cx, a secondary-side branch parallel compensation capacitor Cs0, a compensation inductor Ls0, and the secondary-side second receiving coil Ls2 in the coupling coil, forming a series resonant network. Specifically:

[0078]

[0079] In the formula, ω1 is the operating angular frequency of the system when the operating frequency is f1, i.e., ω1 = 2πf1, L peq The primary branch compensation capacitor C p0and compensation inductor L p0 The equivalent inductance value, C seq The secondary branch is connected in series with a compensation capacitor C. x Parallel compensation capacitor C of secondary branch s0 and compensation inductor L s0 The equivalent capacitance value.

[0080] At this point, the constant current equation of the wireless power transfer system in mode 1 is:

[0081]

[0082] In the formula, A = L peq / ω1C seq B = ω1, where ω1 is the operating angular frequency of the system when the operating frequency is f1, and U in M1 represents the output voltage of the full-bridge inverter circuit, and M1 represents the primary side first transmitting coil L. p1 and the second-side first receiving coil L s1 The mutual inductance value, M2 represents the primary side second transmitting coil L p2 and the second receiving coil L on the secondary side s2 The mutual inductance value.

[0083] In mode 1, the current flows through the first transmitting coil L p1 Current I p1 and flowing through the second transmitting coil L p2 Current I p2 The expression is as follows:

[0084]

[0085] In the formula, R eq This represents the equivalent AC resistance before the rectifier bridge.

[0086] Furthermore, when M1→0 and M2→0, I p1 and I p2 They are respectively equal to:

[0087]

[0088] As can be seen from equation (4), when the receiving coil deviates from the working area or is removed (unloaded), the current flowing through the transmitting coil L p1 The current and the transmitting coil L p2 The current will not increase sharply, thus avoiding the risk of overcurrent in the transmitting coil when the receiving coil is away from the working area or removed (unloaded).

[0089] Furthermore, the input impedance Z of the system in mode 1 in It can be represented as:

[0090]

[0091] From equation (5), it can be seen that the system's input impedance Z in The imaginary part is equal to zero, meaning the system's input impedance is purely resistive. This indicates that zero phase difference between the primary input current and input voltage can be achieved. The system has zero phase angle output characteristics, does not generate reactive power, and fine-tuning the insensitive compensation parameters is expected to achieve zero-voltage conduction of the inverter switching transistor.

[0092] like Figure 3 As shown, when the wireless power transfer system operates at frequency f2, i.e., operating mode 2:

[0093] The primary-side series compensation capacitor C in the primary-side compensation network p1 Primary circuit compensation capacitor C p2 The primary side of the coupling coil, first transmitting coil L p1 The primary side second transmitting coil Lp2 forms a series resonant network; the secondary side compensation network contains a secondary side series compensation capacitor C. s1 Secondary circuit compensation capacitor C s2 The secondary side of the coupling coil, the first receiving coil L s1 Secondary receiving coil L s2 This constitutes a series mistuned network;

[0094] Specifically:

[0095]

[0096] In the formula, ω2 is the operating angular frequency of the system when the operating frequency is f2, that is, ω2=2πf2.

[0097] At this point, the constant current equation of the wireless power transfer system in mode 2 is:

[0098]

[0099] In the formula, ω2 is the operating angular frequency of the system when the operating frequency is f2.

[0100] In mode 2, the current flows through the first transmitting coil L p1 and flowing through the second transmitting coil L p2 Current I p The expression is as follows:

[0101]

[0102] In the formula, R eq This represents the equivalent AC resistance before the rectifier bridge.

[0103] Furthermore, the input impedance Z of the system in mode 2 in It can be represented as:

[0104]

[0105] From equation (5), it can be seen that the system's input impedance Z in The inductive property indicates that the system is likely to achieve zero-voltage turn-on of the inverter switch.

[0106] In equations (2) to (9), U in U represents the output voltage of the full-bridge inverter circuit, and U in =U D ;R eq R represents the equivalent AC resistance before the rectifier bridge, and R eq =R L .

[0107] like Figure 4 As shown, this embodiment provides a mode-switching wireless power transfer system, which is feasible for different coupling mechanisms, and includes the following steps:

[0108] Step 1: Set the DC input voltage U according to the operating requirements. D Rated output current I0, battery load R L The system output current fluctuation ratio δ and the system operating frequency f1 in mode 1;

[0109] Step one specifically includes:

[0110] The definition of the system output current fluctuation ratio δ is as follows:

[0111]

[0112] In formula (1), I Omax I represents the maximum allowable current for a wireless power transfer system. Omin This indicates the minimum current that a wireless power transfer system is allowed to transmit, and specifies the following relationship between them:

[0113]

[0114] In formula (2), I0 represents the rated current transmitted by the wireless power transmission system.

[0115] Step 2: Based on the resonance states or relationships of the primary and secondary side compensation networks in mode 1 and mode 2, obtain the constant current equation of the wireless power transfer system and the quantitative relationship between the compensation parameters.

[0116] Step two specifically includes equations (1) to (2) and equations (6) to (7).

[0117] Step 3: Based on the design requirements of the coupling coil in the wireless power transmission system, obtain the primary side first transmitting coil L using finite element simulation software. p1Primary side second transmitting coil L p2 and the second-side first receiving coil L s1 Secondary receiving coil L s2 The self-inductance value and mutual inductance value under different offset states were obtained, and the relationship between the main coupled mutual inductances M1 and M2 was analyzed using curve fitting.

[0118] Step three specifically includes:

[0119] When the main coupling mutual inductances M1 and M2 are not always equal during the offset of the coupling mechanism, mode 1 is used. The relationship between M1 and M2 is analyzed by curve fitting as follows:

[0120] M1 = CM2 b (12)

[0121] Where M1 represents the first transmitting coil L on the primary side. p1 and the second-side first receiving coil L s1 The mutual inductance value, M2 represents the primary side second transmitting coil L p2 and the second receiving coil L on the secondary side s2 The mutual inductance values; the values ​​of C and b are determined by the actual fitting effect, and the coefficient of determination R of the fitting curve must be guaranteed. 2 >0.99.

[0122] When the main coupling mutual inductances M1 and M2 are always equal during offset in other directions of the coupling mechanism, mode 2 is used, i.e., the relationship between M1 and M2 is as follows:

[0123] M1 = M2 (13)

[0124] Step 4: Define the mutual inductance retention ratio λ, and calculate the output current retention ratio relationship under mode 1, the system operating frequency f2 under mode 2 and the output current retention ratio relationship under mode 2 respectively, based on the constant current equation of the wireless charging system under mode 1 and mode 2, as well as the set system output current fluctuation ratio δ and system operating frequency f1 under mode 1.

[0125] Step four specifically includes:

[0126] The definition of the mutual inductance retention ratio λ of the system is as follows:

[0127]

[0128] In equation (14), M min M0 represents the minimum mutual inductance of the coupling mechanism within the range of output current fluctuation ratio δ, and M0 represents the main coupling mutual inductance when the coupling mechanism is properly aligned. The system output current holding ratio Δ is defined as follows:

[0129]

[0130] In equation (15), IO Let I0 represent the output current of the wireless power transfer system, and I0 represent the rated output current of the wireless power transfer system when the coupling mechanism is aligned. Combining equations (2) and (12), the relationship between the system output current holding ratio Δ in mode 1 is as follows:

[0131]

[0132] In equation (16), parameters B, C, b, and M0 can all be determined by the system operating conditions and the design of the coupling coil. That is, the system output current holding ratio Δ under mode 1 is only related to the system mutual inductance holding ratio λ and parameter A.

[0133] like Figure 5 As shown, to ensure that the output current of the wireless power transmission system is within the system output current fluctuation ratio δ required by the operating conditions, i.e., to limit the system output current holding ratio Δ, the constraints are as follows:

[0134]

[0135] Equation (17) shows that the optimal parameter A can be selected within the output current fluctuation ratio δ to minimize the mutual inductance retention ratio λ, that is, to maximize the system's misalignment tolerance.

[0136] Combining equations (2) and (13), the relationship between the system output current holding ratio Δ in mode 2 is as follows:

[0137]

[0138] In equation (18), the system output current holding ratio Δ under mode 2 is only related to the system mutual inductance holding ratio λ.

[0139] like Figure 6 As shown, to ensure that the output current of the wireless power transmission system is within the system output current fluctuation ratio δ required by the operating conditions, i.e., to limit the system output current holding ratio Δ, the constraints are as follows:

[0140]

[0141] Equation (19) shows that the minimum value of the system mutual inductance retention ratio λ that the system can achieve within the output current fluctuation ratio δ can be determined by the system operating conditions.

[0142] Step 5: Based on the quantitative relationship between the primary and secondary side compensation parameters under working mode 1 and working mode 2, and the optimized value of the mutual inductance retention ratio of mode 1 and mode 2, complete the tuning of the compensation element parameters.

[0143] Step five specifically includes:

[0144] The formula for calculating the system's operating angular frequency ω2 in mode 2 is as follows:

[0145]

[0146] Combining equations (1) and (6) with the optimal parameter A selected in step four, the compensation parameters of the primary and secondary compensation networks of the system can be obtained.

[0147] Therefore, the present invention has the following beneficial effects:

[0148] 1. This invention designs a series hybrid compensation topology network, constructs a quantitative relationship between the compensation topology network and the system operating frequency, uses only the operating frequency as a variable to control the system's operating mode, and constructs all wireless charging system parameters, including compensation parameters, constant current frequency, and coil mutual inductance. Furthermore, because a quantitative relationship is constructed between the output current and the wireless charging system parameters, the hybrid topology is guaranteed to have inherent load-independent output, and all parameters of the wireless charging system can be directly solved using constraint conditions.

[0149] 2. By establishing the mutual inductance fluctuation retention ratio, this invention achieves the global maximization of the system's overall anti-offset capability under the premise of satisfying basic conditions, using the combined current fluctuation ratio as a constraint and the maximum mutual inductance fluctuation retention ratio as the optimization objective. This does not require the introduction of other iterative loops or optimization algorithms, simplifying the multivariate optimization problem into a single-variable optimization problem. It enables the rapid determination of all parameters of the wireless charging system, simplifies the parameter design steps of the wireless charging system, and ensures the efficient output of the constant current mode of the wireless charging system under coupled fluctuations.

[0150] 3. The wireless charging system parameter optimization design method provided by the present invention can be applied to asymmetric magnetic coupling mechanisms and can be extended to other hybrid topologies. It is feasible for different magnetic coupling mechanisms and can maximize the misalignment tolerance of the magnetic coupling mechanism in multiple directions.

[0151] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0152] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A wireless power transfer system with modal switching, characterized in that, Comprise: The series hybrid compensation topology network is composed of a full-bridge inverter circuit, a primary side compensation network, a coupling coil, a secondary side compensation network and a rectification filter circuit. p1 The primary side compensation network includes a primary side series compensation capacitor C p2 , a primary side loop compensation capacitor C p0 and a compensation inductor L p0 ; wherein the primary side branch compensation capacitor C p0 and the compensation inductor L p0 are connected in parallel to form a primary side branch. The input end of the full-bridge inverter circuit is connected with a direct current voltage source U D The one end of the primary series compensation capacitor C p1 is connected with the output end junction A of the full-bridge inverter circuit, and the output end junction B of the full-bridge inverter circuit is respectively connected with the primary loop compensation capacitor C p2 and the one end of the primary branch; the other end of the primary series compensation capacitor C p1 , the primary loop compensation capacitor C p2 and the primary branch are all connected with the primary input end of the coupling coil; the secondary output end of the coupling coil is connected with the input end of the secondary compensation network, the output end of the secondary compensation network is connected with the input end of the rectification filter circuit, and the output end of the rectification filter circuit is connected with a battery load R L . The coupling coil specifically comprises: a primary first transmitting coil L p1 , a primary second transmitting coil L p2 , a secondary first receiving coil L s1 , and a secondary second receiving coil L s2 ; The primary side first transmitting coil L p1 And the primary side second transmitting coil L p2 Adopt the same direction series between the secondary side first receiving coil L s1 And the secondary side second receiving coil L s2 Adopt the same direction series, and electromagnetic coupling occurs between the two coils of the primary side and the two coils of the secondary side; One end of the primary side first transmitting coil L p1 is connected with the primary side series compensation capacitor C p1 , the other end of the primary side first transmitting coil L p1 is connected with the primary side branch and one end of the primary side second transmitting coil L p2 respectively, the other end of the primary side second transmitting coil L p2 is connected with the primary side loop compensation capacitor C p2 ; the secondary side first receiving coil L s1 and the secondary side second receiving coil L s2 are connected with the secondary side compensation network respectively. The secondary side compensation network specifically comprises a secondary side series compensation capacitor C s1 , a secondary side loop compensation capacitor C s2 , a secondary side branch series compensation capacitor C x , a secondary side branch parallel compensation capacitor C s0 and a compensation inductor L s0 ; wherein the secondary side branch parallel compensation capacitor C s0 and the compensation inductor L s0 are connected in parallel to form a secondary side branch; One end of the auxiliary side series compensation capacitor C s1 is connected with one end of the auxiliary side first receiving coil L s1 , and the other end is connected with the junction point C of the rectification filter circuit; the other end of the auxiliary side first receiving coil L s1 is connected with one end of the auxiliary side second receiving coil L s2 and the auxiliary side branch series compensation capacitor C x respectively; the other end of the auxiliary side branch series compensation capacitor C x is connected with one end of the auxiliary side branch; the other end of the auxiliary side second receiving coil L s2 is connected with one end of the auxiliary side loop compensation capacitor C s2 ; the other end of the auxiliary side loop compensation capacitor C s2 and the other end of the auxiliary side branch are both connected with the junction point D of the rectification filter circuit.

2. The wireless power transfer system with modal switching of claim 1, wherein, When the operating frequency of the wireless power transmission system is f1, the operating mode 1 of the wireless power transmission system is: The primary side series compensation capacitor C in the primary side compensation network p1 The primary side branch compensation capacitor C p0 The compensation inductor L p0 The primary side first transmitting coil L in the coupling coil p1 constitutes a series resonance network; the primary side loop compensation capacitor C in the primary side compensation network p2 The primary side branch compensation capacitor C p0 The compensation inductor L p0 The primary side second transmitting coil L in the coupling coil p2 constitutes a series resonance network; the secondary side series compensation capacitor C in the secondary side compensation network s1 The secondary side branch series compensation capacitor C x The secondary side branch parallel compensation capacitor C s0 The compensation inductor L s0 The secondary side first receiving coil L in the coupling coil s1 constitutes a series resonance network; the secondary side loop compensation capacitor C s2 The secondary side branch series compensation capacitor C x The secondary side branch parallel compensation capacitor C s0 The compensation inductor L s0 The secondary side second receiving coil L in the coupling coil s2 constitutes a series resonance network.

3. The wireless power transfer system with modal switching of claim 1, wherein, When the operating frequency of the wireless power transmission system is f2, the operating mode 2 of the wireless power transmission system is: The primary side series compensation capacitor C in the primary side compensation network p1 The primary side loop compensation capacitor C p2 The primary side first transmitting coil L in the coupling coil p1 The primary side second transmitting coil L p2 The primary side series compensation capacitor C in the primary side compensation network s1 The primary side loop compensation capacitor C s2 The primary side first transmitting coil L in the coupling coil s1 The primary side second transmitting coil L s2 The primary side series compensation capacitor C in the primary side compensation network 4. A method for parametric optimization design of a wireless power transfer system with modal switching, based on the system of any one of claims 1-3, characterized in that, Comprise: Step one: set the DC input voltage U according to the working condition requirements D , rated output current I0, battery load R L , system output current fluctuation ratio δ and system operating frequency f1 under working mode 1; Step two: according to the resonance state of the primary and secondary compensation network under the operating mode 1 and the operating mode 2, the quantitative relationship between the constant current equation and the compensation parameter of the wireless power transmission system is obtained respectively; Step three: according to the design requirements of the coupling coils in the wireless power transmission system, the self-inductance values and mutual-inductance values of the primary first transmitting coil L p1 , the primary second transmitting coil L p2 , the secondary first receiving coil L s1 , and the secondary second receiving coil L s2 in different offset states are obtained by means of finite element simulation software, and the relationship between the main coupling mutual inductances M1 and M2 is analyzed using curve fitting; Step four: define the mutual inductance retention ratio λ, and according to the constant current equation of the wireless charging system under the operating mode 1 and the operating mode 2, and the system output current fluctuation ratio δ set and the system operating frequency f1 under the operating mode 1, the output current retention ratio relationship formula under the operating mode 1, the system operating frequency f2 under the operating mode 2 and the output current retention ratio relationship formula are calculated respectively; Step five: according to the quantitative relationship between the primary and secondary compensation parameters under the operating mode 1 and the operating mode 2, and the optimization value of the mutual inductance retention ratio of the operating mode 1 and the operating mode 1, the compensation element parameter is completed.

5. The method for parametric optimization design of wireless power transfer system with modal switching as claimed in claim 4, wherein, The definition formula of the system output current fluctuation ratio δ in the step one is as follows: wherein I Omax represents the maximum value of the current allowed to be transmitted by the wireless power transfer system, I Omin represents the minimum value of the current allowed to be transmitted by the wireless power transfer system, and is subject to the following relationship: Wherein, I0 represents the rated output current.

6. The method for parametric optimization design of wireless power transfer system with modal switching as claimed in claim 4, wherein, The definition formula of the mutual inductance retention ratio λ in the step four is as follows: where M min represents the minimum mutual inductance of the coupling mechanism within the output current fluctuation ratio δ range, and M0 represents the main coupling mutual inductance when the coupling mechanism is in perfect alignment. The definition formula of the system output current retention ratio Δ is as follows: The definition formula of the system output current retention ratio Δ is as follows: where I O represents the output current of the wireless power transfer system, I0represents the rated output current of the wireless power transfer system at the coupling mechanism alignment.

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