Wireless power transmission system and control method thereof

Abstract

The invention provides a wireless power transmission system and a control method thereof. The wireless power transmission system comprises a plurality of active coils, a plurality of relay coils, a receiving coil and a control device. The relay coil comprises a relay coil body and a switched capacitor electrically connected with the relay coil body, and the switched capacitor comprises a capacitor and a switch assembly connected with the capacitor. The receiving coil moves between the upper part of the active coil and the upper part of the repeating coil, and is respectively coupled with the active coil or between the active coil and the repeating coil to form a transmission channel so as to transmit output power. The control device is electrically connected with the receiving coil and is used for acquiring the output power, determining the phase shift angle of the switch assembly according to the output power and controlling the switch assembly according to the phase shift angle of the switch assembly so as to adjust the output power. The detuning rate of the relay coil can be dynamically adjusted, and stable power transmission can be realized when the receiving coil moves under different load values or different coupling change ranges.

Description

Technical Field

[0001] The present application relates to the technical field of wireless power transmission, and in particular to a wireless power transmission system and a control method thereof. Background Art

[0002] Wireless power transmission technology, as an efficient and convenient way to transmit power without direct physical contact, is gradually being applied to various industrial and commercial occasions. However, the current wireless power transmission system cannot solve the problems of power fluctuation caused by the movement of the receiving coil or the power transmission change caused by the change of equivalent load. Summary of the invention

[0003] The present application provides a wireless power transmission system and a control method thereof which can realize stable power transmission when a receiving coil moves.

[0004] The present application provides a wireless power transmission system, comprising:

[0005] multiple active coils;

[0006] A plurality of relay coils, wherein the plurality of relay coils and the plurality of active coils are arranged alternately; the relay coil comprises a relay coil body and a switch capacitor electrically connected to the relay coil body, and the switch capacitor comprises a capacitor and a switch component connected to the capacitor;

[0007] A receiving coil is disposed above the active coil and the relay coil; the receiving coil moves between above the active coil and above the relay coil, and is coupled with the active coil or with the active coil and the relay coil to form a transmission channel to transmit output power; and

[0008] A control device is electrically connected to the receiving coil, and is used to obtain the output power, determine the phase shift angle of the switch component according to the output power, and control the switch component according to the phase shift angle of the switch component to adjust the output power.

[0009] Optionally, when the receiving coil moves to directly above the active coil, the output power is independent of the detuning rate of the relay coil.

[0010] Optionally, when the receiving coil moves to directly above the relay coil, the output power is negatively correlated with the detuning rate of the relay coil.

[0011] Optionally, when the receiving coil is away from the relay coil, the detuning rate of the relay coil gradually increases.

[0012] Optionally, when the receiving coil approaches the relay coil, the detuning rate of the relay coil gradually decreases.

[0013] Optionally, when the receiving coil moves from above the active coil toward above the relay coil, the detuning rate of the relay coil gradually decreases.

[0014] Optionally, when the receiving coil moves from above the relay coil toward above the adjacent active coil, the detuning rate of the relay coil gradually increases.

[0015] Optionally, the control device includes:

[0016] A control module, used for acquiring the output power, and determining the phase shift angle of the switch component according to the acquired output power;

[0017] a modulation module, electrically connected to the control module and configured to determine a duty cycle of the switch component according to a phase shift angle of the switch component; and

[0018] The driving module is electrically connected to the modulation module and the switch component, and is used to control the switch component according to the duty cycle of the switch component.

[0019] Optionally, the control module includes:

[0020] A comparator, used to compare the obtained output power with the expected output power to determine an error value;

[0021] a digital operator, electrically connected to the comparator and used to determine the detuning rate of the relay coil according to the error value; and

[0022] A PI controller is electrically connected to the digital operator and is used to determine the phase shift angle of the switch component according to the detuning rate of the relay coil.

[0023] Optionally, the wireless power transmission system also includes an analog-to-digital conversion module, which is electrically connected to the receiving coil and the control module, and the analog-to-digital conversion module is used to obtain the output power, convert the analog signal of the output power into a digital signal, and transmit it to the control module.

[0024] Optionally, the wireless power transmission system further includes a wireless communication module, and the analog-to-digital conversion module wirelessly communicates with the control module via the wireless communication module.

[0025] Optionally, the analog-to-digital conversion module includes an analog-to-digital converter.

[0026] Optionally, the modulation module includes an enhanced pulse width modulator.

[0027] Optionally, the switch assembly includes two switch tubes connected in reverse, the on-off states of the two switch tubes are complementary states, and the phase shift angles of the two switch tubes are the same.

[0028] Optionally, the switch tube includes a MOS tube; or an IGBT tube.

[0029] Optionally, the wireless power transmission system is applied to a dynamic wireless charging scenario of a mobile device, the multiple transmitting coils and the multiple relay coils are located on the ground, and the receiving coil is located in the mobile device.

[0030] Optionally, the dynamic wireless charging scenario includes at least one of an electric vehicle wireless charging scenario and a logistics robot wireless charging scenario.

[0031] The present application also provides a wireless power transmission system, comprising:

[0032] a plurality of active coils; and

[0033] A plurality of relay coils, wherein the plurality of relay coils and the plurality of active coils are arranged alternately; the relay coil comprises a relay coil body and a switch capacitor electrically connected to the relay coil body, and the switch capacitor comprises a capacitor and a switch component connected to the capacitor; a phase shift angle of the switch component is determined according to the output power transmitted through a transmission channel formed by coupling between the active coil or the relay coil and a receiving coil arranged above, and the switch component is controlled according to the phase shift angle of the switch component to adjust the output power.

[0034] The present application also provides a control method for a wireless power transmission system, which is applied to a wireless power transmission system, wherein the wireless power transmission system comprises a plurality of active coils, a plurality of relay coils and a receiving coil, wherein the plurality of relay coils and the plurality of active coils are arranged alternately; the relay coil comprises a relay coil body and a switch capacitor electrically connected to the relay coil body, wherein the switch capacitor comprises a capacitor and a switch component connected to the capacitor; the receiving coil is arranged above the active coil and the relay coil; the receiving coil moves between above the active coil and above the relay coil, and is respectively coupled with the active coil or with the active coil and the relay coil to form different transmission channels to transmit different output powers;

[0035] The control method comprises:

[0036] obtaining the output power;

[0037] Determining a phase shift angle of the switch component according to the output power; and

[0038] The switch component is controlled according to the phase shift angle of the switch component to adjust the output power.

[0039] The wireless power transmission system of the embodiment of the present application is provided with multiple active coils, multiple relay coils, a receiving coil and a control device, and the multiple relay coils and the multiple active coils are arranged alternately. The receiving coil moves between the top of the active coil and the top of the relay coil, and is respectively coupled with the active coil or with the active coil and the relay coil to form different transmission channels to transmit different output powers. The relay coil is provided with a switch component, and the control device obtains the output power, determines the phase shift angle of the switch component according to the output power, and controls the switch component according to the phase shift angle of the switch component. The detuning rate of the relay coil can be dynamically adjusted, and smooth power transmission can be achieved when the receiving coil moves under different load values ​​or different coupling variation ranges, and the no-load current of the relay coil is minimized to reduce system losses and ensure system safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0041] Figure 1 Shown is a functional block diagram of an embodiment of the wireless power transmission system of the present application.

[0042] Figure 2 shown Figure 1 The specific principle block diagram of the wireless power transmission system shown.

[0043] Figure 3 Shown Figure 2 The equivalent circuit diagram of the active coil, relay coil and receiving coil of the wireless power transmission system shown.

[0044] Figure 4 Shown Figure 3 Circuit diagram of the equivalent capacitance of the switching capacitance of the relay coil of the wireless power transmission system shown.

[0045] Figure 5 Shown Figure 3 The waveform diagram of the duty cycle and current of the switching component of the relay coil of the wireless power transmission system is shown.

[0046] Figure 6 FIG. 1 is a flowchart showing a method for controlling a wireless power transmission system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0047] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0048] The terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application. Unless otherwise defined, the technical terms or scientific terms used in this application should be understood by people with ordinary skills in the field to which this application belongs. The words "first", "second" and similar words used in the specification and claims of this application do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "one" do not indicate a quantitative limit, but indicate that there is at least one. "Multiple" or "several" means at least two. Unless otherwise specified, words such as "front", "rear", "lower" and / or "upper" are only for the convenience of explanation and are not limited to a position or a spatial orientation. Words such as "include" or "comprise" mean that the elements or objects appearing in front of "include" or "comprise" include the elements or objects listed after "include" or "comprise" and their equivalents, and do not exclude other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, and can include electrical connections, whether direct or indirect.

[0049] The singular forms "a", "said" and "the" used in this specification and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0050] The present application provides a wireless power transmission system, including multiple active coils, multiple relay coils, a receiving coil and a control device. Multiple relay coils are arranged alternately with multiple active coils. The relay coil includes a relay coil body and a switch capacitor electrically connected to the relay coil body, and the switch capacitor includes a capacitor and a switch component connected to the capacitor. The receiving coil is arranged above the active coil and the relay coil; the receiving coil moves between the top of the active coil and the top of the relay coil, and is coupled with the active coil or with the active coil and the relay coil to form a transmission channel to transmit output power. The control device is electrically connected to the receiving coil, and the control device is used to obtain the output power, determine the phase shift angle of the switch component according to the output power, and control the switch component according to the phase shift angle of the switch component to adjust the output power. In this way, the detuning rate of the relay coil can be dynamically adjusted, and stable power transmission can be achieved when the receiving coil moves under different load values ​​or different coupling variation ranges, and the no-load current of the relay coil is minimized to the greatest extent, reducing system losses and ensuring system safety.

[0051] The wireless power transmission system and control method of the present application are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the features of the following embodiments and implementations can be combined with each other.

[0052] Figure 1 The figure shows a principle block diagram of an embodiment of the wireless power transmission system 1 of the present application. The wireless power transmission system 1 can be applied to dynamic wireless charging scenarios of mobile devices. Dynamic wireless charging scenarios may include at least one of electric vehicle wireless charging scenarios and logistics robot wireless charging scenarios. In this embodiment, the wireless power transmission system 1 can be used for dynamic wireless charging scenarios of electric vehicles. This embodiment can also be extended to other forms of wireless power transmission systems. For example, it includes electric field type wireless power transmission systems, microwave type wireless power transmission systems, etc., with a wider range of applications. The following mainly takes the dynamic wireless charging scenario of electric vehicles as an example for explanation.

[0053] The wireless power transmission system 1 includes a plurality of active coils 11, a plurality of relay coils 12, a receiving coil 13 and a control device 14. The plurality of relay coils 12 are arranged alternately with the plurality of active coils 11. In this embodiment, the plurality of transmitting coils and the plurality of relay coils 12 are located on the ground and are arranged alternately in sequence. The receiving coil 13 is located in a mobile device, for example, in an electric vehicle.

[0054] exist Figure 1In the illustrated embodiment, the active coil 11 includes an active coil body 111, an AC voltage source 112, an inductor 113, and a capacitor 114. The active coil body 111 serves as a transmitting coil and is excited by the AC voltage source 112, where the AC voltage may be generated by an inverter or other circuit. The inductor 113 and the capacitor 114 form an LCL compensation network or other types of compensation networks to maintain a constant current in the transmitting coil.

[0055] The relay coil 12 includes a relay coil body 121 and a switch capacitor 122 electrically connected to the relay coil body 121. The switch capacitor 122 includes a capacitor 123 and a switch component 124 connected to the capacitor. The switch component 124 includes two switch tubes S1 and S2 connected in reverse. In some embodiments, the switch tubes S1 and S2 may include MOS tubes; or IGBT tubes, which are not limited in this application.

[0056] The receiving coil 13 includes a receiving coil body 131, a resonant capacitor 132 and a load 133. The load 133 can be a battery, a storage capacitor, a resistor or other energy storage or power consumption device. The receiving coil 13 is arranged above the active coil 11 and the relay coil 12. The receiving coil 13 moves between the upper part of the active coil 11 and the upper part of the relay coil 12 (e.g. Figure 1 The receiving coil 13 is coupled with the active coil 11 or with the active coil 11 and the relay coil 12 to form a transmission channel to transmit the output power.

[0057] The control device 14 is electrically connected to the receiving coil 13. The control device 14 is used to obtain the output power, determine the phase shift angle of the switch component 124 according to the output power, and control the switch component 124 according to the phase shift angle of the switch component 124 to adjust the output power. In this embodiment, the control device 14 is electrically connected to the load 133. The control device 14 is used to obtain the output power actually output by the load 133, determine the phase shift angle of the switch component 124 according to the actual output power obtained, and control the switch component 124 according to the phase shift angle of the switch component 124 to adjust the output power so that the output power remains stable. With such a configuration, the phase shift angles of the two switch tubes S1 and S1 of the switch assembly 124 are controlled according to the actual output power of the receiving coil 13, and the detuning rate of the relay coil 12 can be dynamically adjusted, so as to adjust the output power so that the output power reaches the expected output power and maintains a stable output, so as to achieve smooth power transmission when the receiving coil 13 moves under different load values ​​or different coupling variation ranges, and to minimize the no-load current of the relay coil 12, reduce system losses, and ensure system safety. When the user is driving, the wireless power transmission system 1 can maintain a stable output power for the moving receiving coil 13, and perform uninterrupted power transmission to the electric vehicle, meeting the user's real-time energy replenishment needs during driving, reducing the user's dependence on battery capacity, reducing the user's range anxiety, and improving the user experience.

[0058] Figure 2 shown Figure 1 The specific principle block diagram of the wireless power transmission system 1 is shown. Figure 2 In the illustrated embodiment, the control device 14 includes a control module 141, a modulation module 142 and a drive module 143. Among them, the control module 141 is used to obtain the output power and determine the phase shift angle of the switch component 124 according to the output power. The phase shift angle represents the response time delay of the output current or voltage of the switch tube S1 or S2 when the input voltage or current changes. The modulation module 142 is electrically connected to the control module 141 and is used to determine the duty cycle of the switch component 124 according to the phase shift angle of the switch component 124. The duty cycle represents the proportion of time occupied by a high level (or a valid signal occupying a part of the period) in a periodic signal. In this embodiment, the modulation module 142 includes an enhanced pulse width modulator. The drive module 143 is electrically connected to the modulation module 142 and the switch component 124, and is used to control the switch component 124 according to the duty cycle of the switch component 124. With such a configuration, the phase shift angle of the switch component 124 is determined according to the output power, and the duty cycle of the switch component 124 is determined using the phase shift angle of the switch component 124. In this way, the switch component 124 can be precisely controlled, and the detuning rate of the relay coil 12 can be dynamically adjusted, so that smooth power transmission can be achieved when the receiving coil 13 moves under different load values ​​or different coupling variation ranges.

[0059] exist Figure 2 In the illustrated embodiment, the control module 141 includes a comparator 1411, a digital operator 1412, and a PI controller 1413. The comparator 1411 is used to compare the obtained output power with the expected output power to determine the error value. The digital operator 1412 is electrically connected to the comparator 1411, and is used to determine the detuning rate of the relay coil 12 according to the error value. The PI controller 1413 is electrically connected to the digital operator 1412, and is used to determine the phase shift angle of the switch component 124 according to the detuning rate of the relay coil 12. In this way, the actual detuning rate of the switch component 124 can be determined by the actual obtained output power and the expected output power to determine the phase shift angle, so that the phase shift angle of the switch component 124 can be accurately controlled, so that the output power reaches the expected output power and is output stably, and stable power transmission can be achieved when the receiving coil 13 moves under different load values ​​or different coupling variation ranges.

[0060] exist Figure 2 In the illustrated embodiment, the wireless power transmission system 1 further includes an analog-to-digital conversion module 144, which is electrically connected to the receiving coil 13 and the control module 141. The analog-to-digital conversion module 144 is used to obtain the output power, convert the analog signal of the output power into a digital signal, and transmit it to the control module 141. In this embodiment, the analog-to-digital conversion module 144 includes an analog-to-digital converter. Figure 2 In the illustrated embodiment, the wireless power transmission system 1 further includes a wireless communication module 145 , and the analog-to-digital conversion module 144 wirelessly communicates with the control module 141 via the wireless communication module 145 .

[0061] In the above scheme, the execution process of the wireless power transmission system 1 includes: first, sampling the output power of the receiving coil 13, and converting the output power of the analog signal into a digital signal through the analog-to-digital conversion module 144. Then, the converted output power is transmitted to the transmitting end of the control module 141 through the wireless communication module 145. The comparator 1411 is used to obtain the error value according to the sampled output power and the expected power, and the digital operator 1412 is used to calculate the detuning rate α of the relay coil 12 according to the error value, and then the PI controller 1413 is used to calculate the phase shift angle of the switch component 124 (switch tube S1 or S2) according to the detuning rate α of the relay coil 12. The phase shift angle is adjusted by the modulation module 142 The duty ratios D1 and D2 of switches S1 and S2 are converted into the duty ratios D1 and D2 of switches S1 and S2, and sent to the drive module 143. In this embodiment, the drive module 143 may be a drive circuit. The switch tube S1 or S2 is controlled by the drive circuit. With this arrangement, the output power can be stably transmitted during the movement of the electric vehicle, the charging power stability in the dynamic state of the vehicle can be improved, and the user experience can be enhanced.

[0062] Figure 3Shown Figure 2 The equivalent circuit diagram of the active coil 11 , the relay coil 12 and the receiving coil 13 of the wireless power transmission system 1 is shown. Figure 4 Shown Figure 3 A circuit diagram of the equivalent capacitance of the switching capacitor 122 of the relay coil 12 of the wireless power transmission system 1 is shown. Figure 5 Shown Figure 3 The waveform diagram of the duty cycle and current of the switch component 124 of the relay coil 12 of the wireless power transmission system 1 is shown. Figures 1 to 5 As shown, the wireless power transmission system 1 has two channels for transmitting power through magnetic field coupling, one of which is the active coil 11 (transmitting coil) and the receiving coil 13 channel. The other transmission channel is the active coil 11 (transmitting coil), the relay coil 12 and the receiving coil 13 channel. The size or ratio of the output power transmitted by the two transmission channels is mainly determined by the mutual inductance between the two coils (the active coil 11 and the relay coil 12) and the receiving coil 13. The greater the mutual inductance (the stronger the coupling), the more output power is transmitted by the channel. For example, when the receiving coil 13 is located above the active coil 11, the output power is basically all transmitted from the active coil 11 to the receiving coil 13, and the relay coil 12 hardly transmits output power in this position.

[0063] exist Figure 3 In the embodiment shown, Uin1 and Uin2 are two different AC voltage sources 112, Ip1 and Ip2 are corresponding input currents, Iac1 and Iac2 are currents in the active coil 11, Irp is the current of the relay coil 12, and Ire is the current of the receiving coil 13. LT1 and LT2 are resonant inductors, Cac1 and Cac2 are parallel resonant capacitors, Lac1 and Lac2 are active coils 11a and 11b (such as Figure 1 ), Lrp is the inductance of the relay coil 12, Crp is the resonant capacitance of the relay coil 12, Lre is the inductance of the receiving coil 13, Cre is the resonant capacitance of the receiving coil 13, and RL is the equivalent load of the system. Mar1 and Mar2 are the receiving coil 13 and the active coils 11a and 11b (as shown in FIG. Figure 1 Map is the mutual inductance between the active coil 11 and the relay coil 12, and Mpr is the mutual inductance between the relay coil 12 and the receiving coil 13. S1 and S2 are two switching tubes. P1, P2 and P3 represent three different position states, respectively, where P1 represents that the receiving coil 13 is facing the active coil 11, P3 represents that the receiving coil 13 is facing the relay coil 12, P2 represents that the receiving coil 13 is neither facing the active coil 11 nor facing the relay coil 12, that is, it is located between the two, and P2 is not a specific position, but refers to a specific position interval.

[0064] exist Figure 3 In the circuit diagram shown, each AC input power source remains consistent, such as: Uin1 = Uin2. The active coil 11 of the transmitter works in a resonant state. According to the characteristics of the LCL resonant network, the current passing through the active coil 11 remains basically unchanged. The resonance restriction condition of the active coil 11 of the transmitter is:

[0065] ωL Ti =1 / ωC aci =ωL aci (i=1,2) (1)

[0066] Where ω is the system operating angular frequency.

[0067] The corresponding current of the active coil 11 is:

[0068] I aci =U ini / jωL aci (i=1,2) (2)

[0069] It can be seen from the above formulas (1) and (2) that the switching capacitor 122 is used in the relay coil 12 to adjust the external equivalent capacitance value of the resonant capacitor, thereby achieving the adjustment of the detuning rate of the relay coil.

[0070] exist Figure 4 and Figure 5 In the embodiment shown, the external equivalent capacitance value of the switch capacitor 122 of the relay coil 12 can be controlled by the switch tubes S1 and S2. In this embodiment, in this embodiment, the on-off state of the two switch tubes 125 is a complementary state, and the phase shift angles of the two switch tubes are the same. For example, when one of the switch tubes S1 is turned on, the other switch tube S2 is turned off. Or, when one of the switch tubes S1 is turned off, the other switch tube S2 is turned on. The above two switch tubes S1 and S2 are turned on or off synchronously. In this embodiment, the switch tubes S1 and S2 are turned on complementary, and the phase shift angles are both The external equivalent capacitance is Csc.

[0071] Corresponding equivalent capacitance Csc and phase shift angle The relationship is shown as follows:

[0072]

[0073] The detuning rate α is defined by the impedance of the relay coil 12, and its expression is:

[0074]

[0075] Therefore, the external impedance of the relay coil 12 can be expressed as:

[0076] X rp=αωL rp (5)

[0077] It can be seen from the above formulas (1) to (5) that by adjusting the phase shift angle of the switch tubes S1 and S2, the detuning rate of the relay coil 12 can be adjusted, thereby changing the external impedance of the relay coil 12, thereby solving the problem that the system receiving coil 13 must be limited to a detuned state.

[0078] Combination Figures 1 to 5 As shown in the above formulas (1)-(5), according to Kirchhoff's voltage law, the circuit equation of the system when the receiving coil 13 is at position P1-P3 can be obtained as follows:

[0079]

[0080] According to formulas (2)-(4), the currents of the relay coil 12 and the receiving coil 13 can be obtained as follows:

[0081]

[0082] When the receiving coil 13 is far away from the relay coil 12, that is, when the mutual inductance Mpr=0, the current amplitude of the relay coil 12 is:

[0083]

[0084] According to the above formula, when the receiving coil 13 is far away from the relay coil 12, increasing the detuning rate α can suppress the no-load current of the relay coil 12 to the greatest extent, thus solving the problem that the no-load loss current of the relay coil 12 cannot be suppressed to the greatest extent.

[0085] Similarly, the expression of the output power (load power) of the wireless power transmission system 1 can be obtained:

[0086]

[0087] Where θ is the phase angle of the output voltage and current. When the load is a pure resistor, the phase angle is zero.

[0088] Therefore, considering respectively when the receiving coil 13 is facing the active coil 11 or the relay coil 12, the relationship between the load power and the detuning rate α is: when the receiving coil 13 is facing the active coil 11, Mar1 and Map are not zero, and Mpr is zero (corresponding to position P1); when the receiving coil 13 is facing the relay coil 12, Mpr and Map are not zero, and Mar1 is zero (corresponding to position P3).

[0089] Substituting the above conditions into formula (9) we can obtain:

[0090]

[0091]

[0092] In summary, when the receiving coil 13 moves to the top of the active coil 11 (i.e., located at position P1), the output power is independent of the detuning rate α of the relay coil 12. At this time, the detuning rate can be maximized to suppress the current of the relay coil 12. When the receiving coil 13 moves to the top of the relay coil 12 (i.e., located at position P3), the output power is negatively correlated with the detuning rate α of the relay coil 12. At this time, the detuning rate can be minimized to improve the system output power.

[0093] In some embodiments, when the receiving coil 13 is away from the relay coil 12, the detuning rate of the relay coil 12 gradually increases. In some embodiments, when the receiving coil 13 is close to the relay coil 12, the detuning rate of the relay coil 12 gradually decreases. In some embodiments, when the receiving coil 13 moves from above the active coil toward above the relay coil 12, the detuning rate of the relay coil 12 gradually decreases. In some embodiments, when the receiving coil 13 moves from above the relay coil 12 toward above the adjacent active coil, the detuning rate of the relay coil 12 gradually increases. The movement process of the receiving coil 13 is a continuous process (with mutual inductance Mar1 and Mpr). When the receiving coil moves from P1 to P3, the output power decreases accordingly. At this time, it is necessary to reduce the detuning rate of the relay coil 12 and increase the current of the relay coil 12 to increase the power transmitted by the channel. Therefore, the output power can be fed back to the control device 14. According to the negative correlation between the output power and the detuning rate, the output power of the wireless power transmission system 1 can be kept constant in the dynamic process by controlling the detuning rate of the relay coil 12. This solves the problem that the wireless power transmission system 1 cannot maintain a stable output power within different coupling variation ranges.

[0094] From the above formulas (10)-(11), it can be seen that the change of the load RL will only affect the maximum output power level at the P1 position. Under different load values, the wireless power transmission system 1 can still achieve a stable output power in the dynamic process by adjusting the detuning rate of the relay coil, thus solving the problem of output power fluctuation caused by the change of the battery equivalent load of the electric vehicle.

[0095] In some embodiments, the wireless power transmission system 1 includes multiple active coils 11; and multiple relay coils 12, and the multiple relay coils 12 are arranged alternately with the multiple active coils 11; the relay coil 12 includes a relay coil body 121 and a switching capacitor 122 electrically connected to the relay coil body 121, and the switching capacitor 122 includes a capacitor 123 and a switching component 124 connected to the capacitor 123; according to the output power transmitted by the transmission channel formed by the coupling between the active coil 11 or the relay coil 12 and the receiving coil 13 arranged above, the phase shift angle of the switching component 124 is determined, and the switching component 124 is controlled according to the phase shift angle of the switching component 124 to adjust the output power. With such a configuration, the phase shift angle of the switch component 124 is controlled according to the output power actually output by the receiving coil 13, and the detuning rate of the relay coil 12 can be dynamically adjusted. In this way, the output power is adjusted so that the output power reaches the expected output power and maintains a stable output, so as to achieve smooth power transmission when the receiving coil 13 moves under different load values ​​or different coupling variation ranges, thereby minimizing the no-load current of the relay coil 12, reducing system losses, and ensuring system safety.

[0096] Figure 6 FIG. 1 is a flow chart showing a control method of the wireless power transmission system 1 according to an embodiment of the present invention. Figure 6 As shown, the control method of the wireless power transmission system is applied to the above Figures 1 to 5 The wireless power transmission system 1 shown in the embodiment includes a control method including steps S1 to S3.

[0097] Step S1, obtaining output power. In this embodiment, the output power actually output by the load 133 of the receiving coil 13 is obtained.

[0098] Step S2, determining the phase shift angle of the switch component 124 according to the output power. In this embodiment, the phase shift angles of the two switch tubes S1 and S2 of the switch component 124 are determined according to the output power actually output by the receiving coil 13.

[0099] Step S3, control the switch component 124 according to the phase shift angle of the switch component 124 to adjust the output power. In this embodiment, the two switch tubes S1 and S1 of the switch component 124 are controlled according to the phase shift angle of the switch component 124, and the detuning rate of the relay coil 12 can be dynamically adjusted, so as to adjust the output power so that the output power reaches the expected output power, maintain stable output, and realize smooth power transmission when the receiving coil 13 moves under different load values ​​or different coupling change ranges, which can minimize the no-load current of the relay coil 12, reduce system losses, and ensure system safety. For example, when the user is driving, the wireless power transmission system 1 can maintain a stable output power for the moving receiving coil 13, and perform uninterrupted power transmission to the electric vehicle, so as to meet the user's real-time energy replenishment needs during driving, reduce the user's dependence on battery capacity, reduce the user's endurance anxiety, and improve the user experience.

[0100] The execution process of the above control method includes: first, sampling the output power of the receiving coil 13, and converting the output power of the analog signal into a digital signal through the analog-to-digital conversion module 144. Then, the converted output power is transmitted to the transmitting end of the control module 141 through the wireless communication module 145. The comparator 1411 is used to obtain the error value according to the sampled output power and the expected power, and the digital operator 1412 is used to calculate the detuning rate α of the relay coil 12 according to the error value, and then the PI controller 1413 is used to calculate the phase shift angle of the switch component 124 (switch tube S1 or S2) according to the detuning rate α of the relay coil 12. The phase shift angle is adjusted by the modulation module 142 The duty ratios D1 and D2 of switches S1 and S2 are converted into the duty ratios D1 and D2 of switches S1 and S2, and sent to the drive module 143. In this embodiment, the drive module 143 may be a drive circuit. The switch tube S1 or S2 is controlled by the drive circuit. With such a configuration, the output power can be stably transmitted during the movement of the electric vehicle, the charging power stability in the dynamic state of the vehicle can be improved, and the user experience can be enhanced.

[0101] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A wireless power transmission system, characterized in that: include: multiple active coils; A plurality of relay coils, wherein the plurality of relay coils and the plurality of active coils are arranged alternately; the relay coil comprises a relay coil body and a switch capacitor electrically connected to the relay coil body, and the switch capacitor comprises a capacitor and a switch component connected to the capacitor; A receiving coil is disposed above the active coil and the relay coil; the receiving coil moves above the active coil and above the relay coil, and is coupled with the active coil or with the active coil and the relay coil to form a transmission channel to transmit output power; A control device is electrically connected to the receiving coil, and is used to obtain the output power, determine the phase shift angle of the switch component according to the output power, and control the switch component according to the phase shift angle of the switch component to adjust the output power.

2. The wireless power transmission system according to claim 1, characterized in that: When the receiving coil is moved to directly above the active coil, the output power is independent of the detuning rate of the relay coil; or When the receiving coil moves to directly above the relay coil, the output power is negatively correlated with the detuning rate of the relay coil.

3. The wireless power transmission system according to claim 1, characterized in that: When the receiving coil is away from the relay coil, the detuning rate of the relay coil gradually increases; or When the receiving coil approaches the relay coil, the detuning rate of the relay coil gradually decreases.

4. The wireless power transmission system according to claim 1, characterized in that: When the receiving coil moves from above the active coil toward above the relay coil, the detuning rate of the relay coil gradually decreases; or When the receiving coil moves from above the relay coil toward above the adjacent active coil, the detuning rate of the relay coil gradually increases.

5. The wireless power transmission system according to claim 1, characterized in that: The control device comprises: A control module, used for acquiring the output power, and determining the phase shift angle of the switch component according to the acquired output power; a modulation module, electrically connected to the control module and configured to determine a duty cycle of the switch component according to a phase shift angle of the switch component; and The driving module is electrically connected to the modulation module and the switch component, and is used to control the switch component according to the duty cycle of the switch component.

6. The wireless power transmission system according to claim 5, characterized in that: The control module comprises: A comparator, used to compare the obtained output power with the expected output power to determine an error value; a digital operator, electrically connected to the comparator and used to determine the detuning rate of the relay coil according to the error value; and A PI controller is electrically connected to the digital operator and is used to determine the phase shift angle of the switch component according to the detuning rate of the relay coil.

7. The wireless power transmission system according to claim 5, characterized in that: The wireless power transmission system further includes an analog-to-digital conversion module, which is electrically connected to the receiving coil and the control module, and the analog-to-digital conversion module is used to obtain the output power, convert the analog signal of the output power into a digital signal, and transmit the digital signal to the control module; The wireless power transmission system further includes a wireless communication module, and the analog-to-digital conversion module wirelessly communicates with the control module via the wireless communication module; and / or The analog-to-digital conversion module includes an analog-to-digital converter; and / or The modulation module includes an enhanced pulse width modulator.

8. The wireless power transmission system according to any one of claims 1 to 7, characterized in that: The switch assembly includes two switch tubes connected in reverse, the on and off states of the two switch tubes are complementary states, and the phase shift angles of the two switch tubes are the same.

9. The wireless power transmission system according to claim 8, characterized in that: The switch tube includes a MOS tube; or an IGBT tube.

10. The wireless power transmission system according to claim 1, characterized in that: The wireless power transmission system is applied to a dynamic wireless charging scenario of a mobile device, the multiple transmitting coils and the multiple relay coils are located on the ground, and the receiving coil is located in the mobile device.

11. The wireless power transmission system according to claim 10, characterized in that: The dynamic wireless charging scenario includes at least one of an electric vehicle wireless charging scenario and a logistics robot wireless charging scenario.

12. A wireless power transmission system, characterized in that: include: multiple active coils; and A plurality of relay coils, wherein the plurality of relay coils and the plurality of active coils are arranged alternately; the relay coil comprises a relay coil body and a switch capacitor electrically connected to the relay coil body, and the switch capacitor comprises a capacitor and a switch component connected to the capacitor; The phase shift angle of the switch component is determined according to the output power transmitted through the transmission channel formed by coupling between the active coil or the relay coil and the receiving coil arranged above, and the switch component is controlled according to the phase shift angle of the switch component to adjust the output power.

13. A control method for a wireless power transmission system, characterized in that: Applied to a wireless power transmission system, the wireless power transmission system comprises a plurality of active coils, a plurality of relay coils and a receiving coil, wherein the plurality of relay coils and the plurality of active coils are arranged alternately; the relay coil comprises a relay coil body and a switch capacitor electrically connected to the relay coil body, and the switch capacitor comprises a capacitor and a switch component connected to the capacitor; the receiving coil is arranged above the active coil and the relay coil; the receiving coil moves between above the active coil and above the relay coil, and is respectively coupled with the active coil or with the active coil and the relay coil to form different transmission channels to transmit different output powers; The control method comprises: obtaining the output power; Determining a phase shift angle of the switch component according to the output power; and The switch component is controlled according to the phase shift angle of the switch component to adjust the output power.

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