Anti-offset wireless power transmission system with constant-current and constant-voltage output and control method

Abstract

The invention provides an anti-offset wireless power transmission system with constant-current and constant-voltage output and a control method. A system transmitting end comprises a first transmitting coil L1 and a second transmitting coil L3 which are connected in series, and a receiving end comprises a first receiving coil L2 and a second receiving coil L4 which are connected in parallel; the L1 and the L2 are respectively configured with respective compensation circuits to form a CLC-S type topological structure, the L3 and the L4 are respectively configured with respective compensation circuits to form an S-CLC type topological structure, and a variable-structure T type topological structure is also arranged at the receiving end; the variable-structure T-shaped topological structure comprises an inductor L6, an inductor L7, a capacitor C6 and a capacitor C7, the C6 is connected with a circuit break switch S1 in series, and the C7 is connected with a short-circuit switch S2 in parallel; when constant current output is needed, the S1 and the S2 are switched on at the same time, and when constant voltage output is needed, the S1 and the S2 are switched off at the same time. The system has the advantages that the anti-offset capability of the system is further improved, the constant-current / constant-voltage output characteristic is achieved, and meanwhile high transmission efficiency is achieved.

Description

Technical Field

[0001] The present invention relates to the field of wireless power transmission, and in particular to an anti-drift wireless power transmission system with constant current and constant voltage output and a control method. Background Art

[0002] Magnetically Coupled Wireless Power Transfer (MC-WPT) technology is a technology that uses magnetic field as a carrier of energy transmission and uses the principle of electromagnetic induction to achieve non-contact transmission of electrical energy. With the development of modern science and technology, this technology is increasingly used in various fields, such as medical electronics and electric vehicles, due to its advantages of safety, efficiency, flexibility and convenience. In the wireless charging system of electric vehicles, the rechargeable battery is usually a lithium battery, and the constant current / constant voltage charging mode is generally adopted. Figure 1 As shown in the figure, at the initial moment of battery charging, the equivalent resistance of the battery is usually relatively small, so the constant current (CC) charging mode is adopted at this time, the charging current remains constant, and the charging voltage gradually increases with the charging time. In the later stage of charging, the battery voltage remains unchanged after reaching a certain value, and enters the constant voltage (CV) charging mode. In addition, in practical applications, the coupling mechanism of the MC-WPT system will be offset, resulting in a decrease in system performance. Therefore, in view of the offset of the coupling mechanism during wireless charging of electric vehicles and the constant current / constant voltage mode charging of lithium batteries, it is necessary to study a MC-WPT system with constant current / constant voltage output characteristics and anti-offset capability. Summary of the invention

[0003] The primary purpose of the present invention is to provide an anti-deviation wireless power transmission system with constant current and constant voltage output. By adopting a variable structure hybrid topology structure, the anti-deviation capability of the MC-WPT system is further improved and constant current / constant voltage output characteristics are achieved when the coupling mechanism has a larger offset range and a wider load range, while the system has a higher transmission efficiency.

[0004] In order to achieve the above object, the specific technical solutions adopted by the present invention are as follows:

[0005] An anti-offset wireless power transmission system with constant current and constant voltage output includes a transmitting end and a receiving end, wherein the transmitting end includes a first transmitting coil L1 and a second transmitting coil L3 connected in series, and the receiving end includes a first receiving coil L2 and a second receiving coil L4 connected in parallel;

[0006] The first transmitting coil L1 and the first receiving coil L2 are respectively configured with respective compensation circuits to form a CLC-S type topology structure, the second transmitting coil L3 and the second receiving coil L4 are respectively configured with respective compensation circuits to form an S-CLC type topology structure, and a variable structure T-type topology structure is also provided at the receiving end;

[0007] The variable structure T-type topology structure includes an inductor L6, an inductor L7, a capacitor C6 and a capacitor C7, a circuit breaker S1 is connected in series to the capacitor C6, and a short-circuit switch S2 is connected in parallel to the capacitor C7; when a constant current output is required, the circuit breaker S1 and the short-circuit switch S2 are closed at the same time, and when a constant voltage output is required, the circuit breaker S1 and the short-circuit switch S2 are opened at the same time.

[0008] Optionally, the transmitting end further includes a DC power supply and a high-frequency inverter, and the transmitting end of the CLC-S type topology structure and the transmitting end of the S-CLC type topology structure are serially connected to the output end of the high-frequency inverter.

[0009] Optionally, the receiving end also includes a rectifier and filter circuit and an electrical load, and the receiving end of the CLC-S type topology structure and the receiving end of the S-CLC type topology structure are connected in parallel to the input end of the variable structure T type topology structure, and the output end of the variable structure T type topology structure supplies power to the electrical load after passing through the rectifier and filter circuit.

[0010] Optionally, both the disconnect switch S1 and the short-circuit switch S2 in the variable structure T-type topology structure are bidirectional switches.

[0011] Optionally, the CLC-S type topology structure satisfies:

[0012]

[0013] The S-CLC topology meets the following requirements:

[0014]

[0015] Among them, ω is the resonant operating frequency of the system, L0 is the self-inductance of the primary compensation inductor in the CLC-S topology structure, C0 is the series compensation capacitance value of the transmitting coil main circuit in the CLC-S topology structure, C1 is the series compensation capacitance value of the transmitting coil branch in the CLC-S topology structure, C2 is the series compensation capacitance value of the receiving coil in the CLC-S topology structure, C3 is the primary series compensation capacitance value in the S-CLC topology structure, L5 is the self-inductance value of the secondary compensation inductor in the S-CLC topology structure, C4 is the series compensation capacitance value of the receiving coil branch in the CLC-S topology structure, and C5 is the series compensation capacitance value of the receiving coil main circuit in the CLC-S topology structure.

[0016] Optionally, first follow the charging current I out Perform constant current charging, then detect the charging voltage. When the charging voltage reaches When the charging voltage is switched to constant voltage charging state, R L is the load value at the switching point, M 12 The mutual inductance between the first transmitting coil L1 and the first receiving coil L2, M 34 is the mutual inductance between the second transmitting coil L3 and the second receiving coil L4.

[0017] Optionally, it is characterized in that the first transmitting coil L1 and the first receiving coil L2 both adopt DD type coils and have the same self-inductance, the second transmitting coil L3 and the second receiving coil L4 both adopt Q type coils and have the same self-inductance, the first transmitting coil L1 and the second transmitting coil L3 are stacked at the transmitting end to form a DDQ coil structure, and the first receiving coil L2 and the second receiving coil L4 are stacked at the receiving end to form a DDQ coil structure.

[0018] Based on the above system, the present invention also provides a control method for an anti-offset wireless power transmission system with constant current and constant voltage output, the key of which is that it includes the following steps:

[0019] S1: Start charging, close the circuit breaker S1 and the short-circuit switch S2, and the system enters the constant current charging mode;

[0020] S2: Detect the load voltage to determine whether it reaches the switching value; if it does, proceed to step S3, otherwise, repeat the detection;

[0021] S3: disconnect the circuit breaker S1 and the short-circuit switch S2, and the system enters a constant voltage charging mode;

[0022] S4: Load shedding, charging ends.

[0023] Optionally, the switching value of the load voltage in step S2 is calculated as follows:

[0024]

[0025] Where: R L is the load value at the switching point, M 12 The mutual inductance between the first transmitting coil L1 and the first receiving coil L2, M 34 is the mutual inductance between the second transmitting coil L3 and the second receiving coil L4.

[0026] The remarkable effects of the present invention are:

[0027] The present invention proposes an anti-deviation wireless power transmission system with constant current and constant voltage output. By adopting a variable structure hybrid topology structure, the anti-deviation capability of the MC-WPT system is further improved and constant current / constant voltage output characteristics are achieved when the coupling mechanism has a larger offset range and a wider load range, while the system has a higher transmission efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings of the present invention are as follows.

[0029] Figure 1 This is a schematic diagram of the constant current / constant voltage charging process of an existing electric vehicle;

[0030] Figure 2 is a circuit diagram of a specific embodiment of the present invention;

[0031] Figure 3 It is a structural schematic diagram of a bidirectional switch in a specific embodiment of the present invention;

[0032] Figure 4 It is a traditional T-type topology;

[0033] Figure 5 It is a variable structure T-type topology structure;

[0034] Figure 6 is an equivalent circuit diagram of a constant current charging mode in a specific embodiment of the present invention;

[0035] Figure 7 is an equivalent circuit diagram of a constant voltage charging mode in a specific embodiment of the present invention;

[0036] Figure 8 It is a flow chart of the control method in a specific embodiment of the present invention;

[0037] Fig. 9 This is a design diagram of the coil structure in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0039] like Figure 2 An anti-offset wireless power transmission system with constant current and constant voltage output shown in the figure comprises a transmitting end and a receiving end, wherein the transmitting end comprises a first transmitting coil L1 and a second transmitting coil L3 connected in series, and the receiving end comprises a first receiving coil L2 and a second receiving coil L4 connected in parallel;

[0040] The first transmitting coil L1 and the first receiving coil L2 are respectively configured with respective compensation circuits to form a CLC-S type topology structure, the second transmitting coil L3 and the second receiving coil L4 are respectively configured with respective compensation circuits to form an S-CLC type topology structure, and a variable structure T-type topology structure is also provided at the receiving end;

[0041] The variable structure T-type topology structure includes an inductor L6, an inductor L7, a capacitor C6 and a capacitor C7, a circuit breaker S1 is connected in series to the capacitor C6, and a short-circuit switch S2 is connected in parallel to the capacitor C7; when a constant current output is required, the circuit breaker S1 and the short-circuit switch S2 are closed at the same time, and when a constant voltage output is required, the circuit breaker S1 and the short-circuit switch S2 are opened at the same time.

[0042] pass Figure 2 It can be seen that in this system, the variable structure hybrid topology circuit connects the input ends of the CLC-S type and S-CLC type topologies in series and connects the output ends in parallel. This part is the front-stage circuit, which is mainly used to improve the anti-offset performance of the system. And on this basis, the variable structure T-type compensation topology is added to the output end to form a post-stage T-type circuit. The circuit is composed of two compensation inductors, two compensation capacitors and two bidirectional switches, so as to change the output unit structure of the hybrid topology circuit to achieve the purpose of constant current / constant voltage switching. Figure 2 In the figure, E is the DC power supply, Q1-Q4 are the MOSFETs that make up the inverter module, D1-D4 are the diodes that make up the rectifier module, and U in is the fundamental voltage after inversion, the input current is I0, C0, C1 are the series capacitors of the CLC-S type compensation topology, L0 is the parallel compensation inductor, C2 is the series compensation capacitor of the secondary side, L1, L2 are the primary and secondary self-inductances of the CLC-S type compensation topology, M 12 is the mutual inductance of the primary and secondary sides; C3 is the primary series compensation capacitor of the S-CLC compensation topology, C4 and C5 are the secondary series compensation capacitors, L5 is the secondary parallel compensation inductor, L3 and L4 are the primary and secondary self-inductances of the S-CLC compensation topology, M 34 is the original secondary side mutual inductance, M 13 is the cross-coupled mutual inductance of the primary side of the CLC-S and S-CLC compensation topologies, M 24 is the cross-coupled mutual inductance of the secondary side; L6, L7, C6 and C7 constitute the variable structure T-type compensation topology of the output unit; U out is the output voltage, R e is the equivalent AC load resistance, R L is the actual resistance load, U o ,I o In order to achieve constant current / constant voltage switching, a bidirectional switch is needed to change the structure of the T-type topology. In specific implementation, the bidirectional switch structure is as follows: Figure 3 shown.

[0043] The present invention uses a variable structure to reorganize the output end, forming an output end variable structure T-type compensation topology, and uses the switching of a bidirectional switch to change the system equivalent topology structure to change the output characteristics of the system. When the load requires constant current charging, the output end structure of the system is changed by the bidirectional switch, so that the system output presents a constant current characteristic; when the load requires constant voltage charging, the output end structure is changed by the bidirectional switch, so that the system output presents a constant voltage characteristic.

[0044] Traditional T-type compensation topology Figure 4 As shown. Z0, Z1 and Z2 are three impedance parts, distributed in the three branches of the T-type circuit. I , I0 is the input voltage and input current of the T-type topology, U o , I1 is the output voltage and output current.

[0045] According to Kirchhoff's law, the output characteristics of the T-type compensation topology are as follows:

[0046] U o +I1Z1=I2Z2

[0047] For the current, the following relationship holds

[0048] I1+I2=I0

[0049] Substituting into the above formula we can get:

[0050] U o =I0Z2-I1(Z1+Z2)

[0051] When Z1+Z2=0, then:

[0052] U o =I0Z2

[0053] That is, when Z1=-Z2, the output voltage changes linearly with the input current. When the input is a constant current input, the T-type compensation topology can achieve a constant voltage output.

[0054] Similarly, analyzing the input characteristics of the T-type compensation topology, Kirchhoff's voltage-current law can be used to obtain:

[0055] U I =I0Z0+Z2I2

[0056] Substituting in, we get:

[0057] U I =I0(Z0+Z2)-I1Z2

[0058] When Z0+Z2=0, we have:

[0059]

[0060] That is, when Z0=-Z2, the output current changes linearly with the input voltage. When the input is a constant voltage input, the T-type compensation topology can achieve a constant current output.

[0061] As long as Z0=-Z2=Z1 is satisfied, the T-type topology can realize constant voltage and constant current output conversion. According to the characteristics of the T-type topology, the present invention designs the following Figure 5 The variable structure T-type compensation topology shown in FIG. 1 satisfies Z0=-Z2=Z1 when switches S1 and S2 are closed. Figure 4 Equivalent, constant voltage and constant current output conversion can be achieved. When switches S1 and S2 are turned off, that is, Z2 in the T-type topology is removed from the circuit, and Z3 is added to the circuit, at this time Z0+Z1=-Z3, the system output is the same as the output without T-type compensation topology, that is, the system output characteristics are not changed.

[0062] Combined with the previous description, when the constant current is working, when the bidirectional switches S1 and S2 are closed, the equivalent hybrid topology circuit is as follows Figure 6 As shown, in order to simplify the analysis process of the circuit model, the hybrid topology circuit is divided into two parts: the front-stage circuit and the rear-stage T-type circuit. Figure 6 Middle U out1 Indicates the output voltage of the first part of the front stage circuit, U out2 Represents the output voltage of the second-stage T-type circuit, R E is the equivalent impedance of the subsequent T-type circuit. The constant voltage output of the previous circuit can be regarded as the constant voltage input source of the subsequent T-type circuit.

[0063] When the input of the subsequent T-type circuit is a constant voltage source, the output is a constant current. According to the circuit resonance principle, we can get:

[0064]

[0065] Ignoring the internal resistance of each part of the system, using Kirchhoff's voltage and current law to analyze the circuit, we can get:

[0066]

[0067] In the above formula:

[0068]

[0069] When the cross-coupling M 13 、M 14 、M 23 、M 24 When the influence of can be ignored, the output voltage and input impedance can be obtained as:

[0070]

[0071] Further, the current of each branch in the circuit can be obtained:

[0072]

[0073] According to the analysis of T-type compensation topology, we can get:

[0074]

[0075] The input impedance of the T-type compensation topology is obtained, that is, R E for:

[0076]

[0077] Thus we can get:

[0078]

[0079] From the above formula, we can see that the input impedance of the hybrid topology circuit in constant current mode is purely resistive, and there is no phase difference between the input voltage and the input current, which is beneficial to reduce the system reactive power and improve the system transmission efficiency. Finally, the output current can be obtained as:

[0080]

[0081] From the above formula, we can see that when the cross coupling M 13 、M 14 、M 23 、M 24 When the influence of can be ignored, the output current has nothing to do with the load value. The proposed variable structure hybrid topology can achieve constant current output when the input voltage is constant. And the output current is only related to the input voltage U in , system operating frequency ω, mutual inductance M 12 、M 34 , which is related to the resonant capacitors C0, C5 and inductor L7. When the MC-WPT system is offset, the mutual inductance M of the MC-WPT system 12 、M 34 will decrease, and M 12 , C0 and M 34 , C5 changes in opposite directions. At this time, the CLC-S topology will increase the output current, and the S-CLC topology will reduce the output current. Therefore, for the hybrid topology, the output current of the system can be kept constant by reasonably designing the system parameters.

[0082] When the bidirectional switches S1 and S2 in the system are disconnected, that is, the two back-to-back MOSFETs are turned off, the equivalent hybrid topology circuit is as follows: Figure 7As shown, similar to the constant current mode, the circuit is divided into two parts: the front stage circuit and the rear stage T-type circuit. Figure 7 Middle U out1 Indicates the output voltage of the first part of the front stage circuit, U out2 Represents the output voltage of the second-stage T-type circuit, R E is the equivalent resistance before the next stage T-type circuit. The constant voltage output of the previous stage circuit can be regarded as the constant voltage input source of the next stage T-type circuit. The analysis of the previous stage circuit is the same as that of the constant current mode, so this section mainly analyzes the T-type topology after the switch is switched. According to the circuit resonance principle, it can be obtained:

[0083]

[0084] From the above formula, we can get the input impedance of the T-type compensation topology, that is, R E for:

[0085]

[0086] It can be known that the system output voltage will remain unchanged after passing through the subsequent T-type circuit. At this time, the system output voltage is:

[0087]

[0088] The system input impedance is:

[0089]

[0090] According to the above formula, we can know that the input impedance of the system is purely resistive in constant voltage mode, which means that the system can achieve ZPA in normal operation, reduce reactive power, and improve system transmission efficiency. 13 、M 14 、M 23 、M 24 When the influence of can be ignored, it can be seen that the system can achieve constant voltage output regardless of the load, and the mutual inductance M of the CLC-S and S-CLC compensation topologies is 12 、M 34 Therefore, when the MC-WPT system is offset and causes the mutual inductance to fluctuate, the system output voltage can be kept constant by reasonably optimizing the system compensation parameters, thereby improving the anti-offset capability of the MC-WPT system.

[0091] Combined with the analysis of the variable structure hybrid topology circuit proposed above, it is necessary to change the state of the bidirectional switch to switch the MC-WPT system from constant current mode to constant voltage mode. Due to the presence of inductance and capacitance components in the circuit, voltage or current impact problems may occur. In order to avoid the impact of energy impact, the present invention optimizes the load switching point and then designs a topology smooth switching strategy. When implemented specifically:

[0092] In order to reduce the output power fluctuation before and after the system working mode switching, it is necessary to optimize the load design during switching. Therefore, the output power of the constant current mode can be equal to the output power of the constant voltage mode. From the above analysis, the output power of the constant current mode and the constant voltage mode can be obtained as:

[0093]

[0094] Let P in the above formula outcv =P outcc , replace the load R in the formula L Assuming it as a variable and other parameters as constants, the load resistance at the switching point can be obtained as:

[0095]

[0096] In the above formula, U out is the charging voltage during constant voltage charging, I out is the charging current of the constant current charging process. As can be seen from the above formula, when designing the MC-WPT system parameters, the system's output voltage, current and switching point load can be designed according to the battery charging curve, that is, the switching point load value is determined according to the above formula, and the voltage value at this time is used as the switching voltage reference value, that is, during constant current charging, as the resistance value continues to increase, the load voltage also continues to increase. When the voltage value is detected to reach the set value, the load resistance also reaches the switching point at this time, and the T-type compensation topology switches the switch to enter the constant voltage charging mode. Therefore, by detecting the switching point voltage, it can be ensured that the load end power fluctuation is reduced when the system switches the working mode, and a smooth switching topology is achieved.

[0097] Therefore, combined with Figure 8 As shown, this embodiment provides a control method for an anti-offset wireless power transmission system with constant current and constant voltage output, comprising the following steps:

[0098] S1: Start charging, close the circuit breaker S1 and the short-circuit switch S2, and the system enters the constant current charging mode;

[0099] S2: Detect the load voltage to determine whether it reaches the switching value; if it does, proceed to step S3, otherwise, repeat the detection;

[0100] S3: disconnect the circuit breaker S1 and the short-circuit switch S2, and the system enters a constant voltage charging mode;

[0101] S4: Load shedding, charging ends.

[0102] The switching value of the load voltage in step S2 is calculated as follows:

[0103]

[0104] Where: R L is the load value at the switching point, M 12 The mutual inductance between the first transmitting coil L1 and the first receiving coil L2, M 34 is the mutual inductance between the second transmitting coil L3 and the second receiving coil L4.

[0105] In addition, in order to prevent the system structure from being affected by the same-side cross-coupling and the opposite-side cross-coupling, the coupling mechanism usually needs to meet the following conditions during implementation: ① The coupling mechanism needs to have two primary-side transmitting coils and two secondary-side receiving coils; ② When the MC-WPT system is offset, its self-inductance needs to remain unchanged, and the two pairs of mutual inductances M 12 and M 34 There needs to be the same change trend and the cross-coupling should be as small as possible.

[0106] According to existing research, the characteristics of DDQ coils are M DDQ ≈0, that is, the mutual inductance of the DD coil and the Q coil in the primary transmitting coil in the DDQ coil is approximately zero. Therefore, combined with Fig. 9 It can be seen that in the specific implementation of the present invention, the first transmitting coil L1 and the first receiving coil L2 both adopt DD-type coils and have the same self-inductance, the second transmitting coil L3 and the second receiving coil L4 both adopt Q-type coils and have the same self-inductance, the first transmitting coil L1 and the second transmitting coil L3 are stacked at the transmitting end to form a DDQ coil structure, and the first receiving coil L2 and the second receiving coil L4 are stacked at the receiving end to form a DDQ coil structure.

[0107] In summary, the present invention provides an anti-deviation wireless power transmission system and control method with constant current and constant voltage output, which further improves the anti-deviation capability of the MC-WPT system and realizes constant current / constant voltage output characteristics, while enabling the system to have higher transmission efficiency.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. An anti-drift wireless power transmission system with constant current and constant voltage output, comprising a transmitting end and a receiving end, characterized in that: The transmitting end includes a first transmitting coil L1 and a second transmitting coil L3 connected in series, and the receiving end includes a first receiving coil L2 and a second receiving coil L4 connected in parallel; The first transmitting coil L1 and the first receiving coil L2 are respectively configured with respective compensation circuits to form a CLC-S type topology structure, the second transmitting coil L3 and the second receiving coil L4 are respectively configured with respective compensation circuits to form an S-CLC type topology structure, and a variable structure T-type topology structure is also provided at the receiving end; The variable structure T-type topology structure includes an inductor L6, an inductor L7, a capacitor C6 and a capacitor C7, a circuit breaker S1 is connected in series to the capacitor C6, and a short-circuit switch S2 is connected in parallel to the capacitor C7; when a constant current output is required, the circuit breaker S1 and the short-circuit switch S2 are closed at the same time, and when a constant voltage output is required, the circuit breaker S1 and the short-circuit switch S2 are opened at the same time.

2. The anti-offset wireless power transmission system with constant current and constant voltage output according to claim 1, characterized in that: The transmitting end also includes a direct current power supply and a high-frequency inverter. The transmitting end of the CLC-S type topology structure and the transmitting end of the S-CLC type topology structure are serially connected to the output end of the high-frequency inverter.

3. The anti-offset wireless power transmission system with constant current and constant voltage output according to claim 1, characterized in that: The receiving end also includes a rectifier and filter circuit and an electrical load. The receiving end of the CLC-S type topology structure and the receiving end of the S-CLC type topology structure are connected in parallel to the input end of the variable structure T type topology structure. The output end of the variable structure T type topology structure supplies power to the electrical load after passing through the rectifier and filter circuit.

4. The anti-offset wireless power transmission system with constant current and constant voltage output according to claim 1 or 3, characterized in that: The disconnect switch S1 and the short-circuit switch S2 in the variable structure T-type topology structure are both bidirectional switches.

5. The anti-offset wireless power transmission system with constant current and constant voltage output according to claim 1, characterized in that: The CLC-S topology meets the following requirements: The S-CLC topology meets the following requirements: Among them, ω is the resonant operating frequency of the system, L0 is the self-inductance of the primary compensation inductor in the CLC-S topology structure, C0 is the series compensation capacitance value of the transmitting coil main circuit in the CLC-S topology structure, C1 is the series compensation capacitance value of the transmitting coil branch in the CLC-S topology structure, C2 is the series compensation capacitance value of the receiving coil in the CLC-S topology structure, C3 is the primary series compensation capacitance value in the S-CLC topology structure, L5 is the self-inductance value of the secondary compensation inductor in the S-CLC topology structure, C4 is the series compensation capacitance value of the receiving coil branch in the CLC-S topology structure, and C5 is the series compensation capacitance value of the receiving coil main circuit in the CLC-S topology structure.

6. The anti-offset wireless power transmission system with constant current and constant voltage output according to claim 5, characterized in that: First, according to the charging current I out Perform constant current charging, then detect the charging voltage. When the charging voltage reaches When the charging voltage is switched to constant voltage charging state, R L is the load value at the switching point, M 12 The mutual inductance between the first transmitting coil L1 and the first receiving coil L2, M 34 is the mutual inductance between the second transmitting coil L3 and the second receiving coil L4.

7. The anti-offset wireless power transmission system with constant current and constant voltage output according to claim 5 or 6, characterized in that: The first transmitting coil L1 and the first receiving coil L2 both adopt DD type coils and have the same self-inductance, the second transmitting coil L3 and the second receiving coil L4 both adopt Q type coils and have the same self-inductance, the first transmitting coil L1 and the second transmitting coil L3 are stacked at the transmitting end to form a DDQ coil structure, and the first receiving coil L2 and the second receiving coil L4 are stacked at the receiving end to form a DDQ coil structure.

8. A control method for an anti-offset wireless power transmission system with constant current and constant voltage output according to any one of claims 5 to 7, characterized in that: The following steps are involved: S1: Start charging, close the circuit breaker S1 and the short-circuit switch S2, and the system enters the constant current charging mode; S2: Detect the load voltage to determine whether it reaches the switching value; if it does, proceed to step S3, otherwise, repeat the detection; S3: disconnect the circuit breaker S1 and the short-circuit switch S2, and the system enters a constant voltage charging mode; S4: Load shedding, charging ends.

9. The control method of the anti-offset wireless power transmission system with constant current and constant voltage output according to claim 8, characterized in that: The switching value of the load voltage in step S2 is calculated as follows: Where: R L is the load value at the switching point, M 12 The mutual inductance between the first transmitting coil L1 and the first receiving coil L2, M 34 is the mutual inductance between the second transmitting coil L3 and the second receiving coil L4.

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