Wireless power transmission system with multiple transmitting coils and multiple parallel inverters and high offset resistance and interoperability

Abstract

The invention provides a wireless power transmission system with multiple transmitting coils and multiple parallel inverters, which has strong offset resistance and interoperability. The wireless power transmission system comprises a primary side circuit, a secondary side circuit and a decoupling module, the primary side circuit converts the direct current into multiple paths of alternating current to drive at least two transmitting coils; the secondary circuit receives electric energy through a single receiving coil, the electric energy is supplied to a load after being rectified, and the secondary circuit is not provided with an additional decoupler; the decoupling module realizes electromagnetic decoupling between the transmitting coils through a passive impedance element, so that the system meets equivalent mutual inductance, the method realizes addition of absolute values of a plurality of mutual inductances between the primary side and the secondary side, and the anti-offset capability of the system is improved; due to the fact that an absolute value summation calculation mode is adopted in the equivalent mutual inductance, the zero-crossing problem in the multi-polarity coil coupling process is solved, and the compatibility between the coils is enhanced through the method.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of wireless power transfer, and in particular, relates to a multi-transmit coil multi-parallel inverter wireless power transfer system with strong anti-offset and interoperability. BACKGROUND

[0002] Wireless power transfer (WPT) technology has shown significant application value in the fields of electric vehicle dynamic charging, consumer electronics intelligent device non-inductive endurance, medical implant device long-term energy supply, underwater operation device power supply, deep space exploration, etc. due to its non-physical contact power transmission characteristics, which breaks through the limitations of traditional conductor connection, ensures safety, and significantly improves the convenience of power supply. Among them, the electromagnetic induction type wireless power transfer technology has become the most mature and most active mainstream scheme in the current wireless power supply field due to its deep research accumulation and wide scene adaptability. This technology is based on Faraday's law of electromagnetic induction, and energy transfer is achieved through the magnetic field coupling of a loosely coupled transformer. In actual application, the transmit coil and the receive coil of the loosely coupled transformer inevitably offset and dislocate, resulting in a decrease in the coupling coefficient and affecting the transmission power and efficiency.

[0003] To improve the anti-offset capability of the system, a multi-coil structure that is mutually decoupled is often used as a transmit coil or a receive coil, such as a DDQ type coil and a BP type coil. Such a coil has a magnetic field in multiple directions, and natural decoupling is achieved through the multi-directional magnetic field. Magnetic circuit natural decoupling design can effectively suppress cross-coupling and avoid reactive components, but it limits the size and design freedom of the coil. In addition, in actual application, the coil types of wireless chargers and charging products from different manufacturers may be different, which leads to compatibility and interoperability of wireless charging. For example, a multi-pole magnetic field coil (such as a DD type) and a single-pole magnetic field coil (such as a Q type) have a coupling coefficient of zero in the aligned state and cannot transfer energy. The magnetic field distribution in this case is shown in Figure 1 For a WPT system with constant voltage output, a coupling coefficient of zero may cause the load to power down and damage the circuit. In summary, a wireless power transfer system with anti-offset and interoperability needs to be studied. SUMMARY

[0004] To solve the above problems, the present application provides a multi-transmit coil multi-parallel inverter wireless power transfer system with strong anti-offset and interoperability, wherein the multiple transmit coils are decoupled through passive elements without additional structural design.

[0005] The present application achieves the following technical solutions: a multi-transmit coil multi-parallel inverter wireless power transfer system with strong anti-offset and interoperability: The wireless power transmission system includes a primary-side circuit, a secondary-side circuit, and a decoupling module; The primary circuit converts direct current into multiple alternating currents to drive at least two transmitting coils; The secondary circuit receives electrical energy through a single receiving coil, which is then rectified and supplied to the load. The secondary circuit has no additional decoupling device. The decoupling module achieves electromagnetic decoupling between the transmitting coils through passive impedance elements, enabling the system to meet the equivalent mutual inductance requirement. ,in M PS It is the original equivalent mutual inductance of the secondary side. M Pi It is the receiving coil and the transmitting coil. i Mutual attraction between them.

[0006] Furthermore, the passive impedance element is an inductor or capacitor, connected between the transmitting coil branches to achieve electromagnetic decoupling between the transmitting coils.

[0007] Furthermore, the primary-side circuit includes at least two sets of transmitting circuits, each set of transmitting circuits consisting of a half-bridge inverter and a compensation inductor. L fn Compensation capacitor C fn Compensation capacitor C n and transmitting coil L n composition; The half-bridge inverter includes two switching transistors; All transmitting branches share a common DC input voltage. U in and capacitor C in ; Different transmitting branches are connected by passive impedance elements.

[0008] Furthermore, the secondary circuit includes a single receiving coil and a compensation capacitor. C p A full-bridge rectifier consisting of four rectifier diodes, and a filter capacitor. C F and load resistance R L .

[0009] Furthermore, the wireless power transmission system also includes a control module. The control module dynamically adjusts the phase of the drive signal according to the polarity of the receiving coil and the mutual inductance with each transmitting coil, and reverses the phase of the drive signal by changing the timing of the inverter switching transistors.

[0010] Beneficial effects of the invention The multiple transmitting coils of the application realize decoupling through passive elements, without the need for additional structural design, are suitable for multi-coil expansion, and therefore have high coil design freedom.

[0011] The method of the application realizes the addition of the absolute values of multiple mutual inductances between the primary and secondary sides, improves the anti-offset capability of the system, and successfully solves the zero-crossing problem in the coupling process of multiple polarity coils by using the absolute value summation calculation method of equivalent mutual inductance, thereby enhancing the compatibility between coils.

[0012] The application can improve the interoperability and compatibility of the system, so that different transmitting coils and receiving coils can work normally. At the same time, since no additional devices are added to the secondary side, the lightweight design of the secondary side is facilitated.

[0013] The application eliminates the coupling zero-crossing phenomenon and also improves the safety performance of the wireless power transmission system, and can significantly improve the anti-offset capability and interoperability of the system. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a coupling zero-crossing schematic diagram; Figure 2 is a WPT system circuit diagram of a multi-coil multi-series rectifier; wherein (a) two coils, M 12 ; (b) three coils, M 12 = M 13 = M 23 ; (c) three coils, M 13 = M 23 ≠ M 12 ; (d) four coils, M 12 = M 13 = M 14 = M 23 = M 24 = M 34 ; (e) four coils, M 23 = M 24 = M34 ≠ M 12 = M 13 = M 14 ; (f) Four coil, M 12 ≠ M 13 = M 14 = M 23 = M 24， M 34 ≠ M 13 = M 14 = M 23 = M 24 ; (g) Four coil, M 34 ≠ M 23 = M 24 ≠ M 14 = M 13 = M 12 ; Figure 3 is a schematic diagram of a coil; Figure 4 is a schematic diagram of topology; Figure 5 is a schematic diagram of anti-offset; Figure 6 is a schematic diagram of driving signal; Figure 7 is a curve of output voltage varying with load when the coil is aligned. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0016] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are conventional materials, reagents, methods and instruments in the art unless otherwise specified, and can be obtained by commercial channels by those skilled in the art.

[0017] Combination Figures 1 to 7 The present application provides a multi-transmit coil multi-parallel inverter wireless power transmission system with strong anti-offset and interoperability; The circuit diagram of the WPT system based on multi-transmit coil multi-series inverter is shown in Figure 2 Commonly used are two coils, three coils and four coils, among which three coils include two cases, and four coils include four cases, and other cases can be constructed by adding differential mode inductance or common mode inductance Figure 2 For the case of more than four transmit coils, analogy can be made according to Figure 2 Form.

[0018] Figure 2 The parameter design method of (a) satisfies formula (1): (1) The compensation inductance and capacitance satisfy formula (2): (2) Figure 2 The parameter design method of (b) satisfies formula (3): (3) The compensation inductance and capacitance satisfy formula (4): (4) Figure 2 The parameter design method of (c) satisfies formula (5): (5) The compensation inductance and capacitance satisfy formula (6): (6) Figure 2 The parameter design method of (d) satisfies formula (7): (7) The compensation inductance and capacitance satisfy formula (8): (8) Figure 2 The parameter design method of (e) satisfies formula (9): (9) The compensation inductance and capacitance satisfy formula (10): (10) Figure 2 The parameter design method of (f) satisfies formula (11): (11) The compensation capacitor satisfies formula (12): (12) Figure 2 The parameter design method of (g) satisfies formula (13): (13) The compensation capacitor satisfies formula (14): (14) in Z i It is an inductor or capacitor, and 1 / Z i It can be 0 ( i =1~3), The above circuit can achieve the sum of the absolute values ​​of the mutual inductance between the primary and secondary sides, that is... ,in M PS It is the original equivalent mutual inductance of the secondary side. M Pi It is a receiving coil L P With transmitting coil L i Mutual intuition between them i =1~4).

[0019] by Figure 2 Taking case (a) as an example, the primary and secondary coils have the same external dimensions. The receiving coil is square with 12 turns, and the transmitting coil is a DD coil with 11 turns in each case. Figure 3 As shown. The compensation topology adopts LCC / S, and the WPT system circuit diagram is as follows. Figure 4 As shown. Among them U in It is the DC input voltage; Q 1~ Q 4 is the inverter switching transistor; C p , C f1 , C f2 , C 1, C 2 is the compensation capacitor; L f1 , L f2 It is a compensating inductor; L p It is the self-inductance of the secondary coil;L 1, L 2 is the self-inductance of the primary coil; M s1 , M s2 They are L s and L 1, L Mutual induction between 2; M 12 It is the primary coil L 1 and L Mutual induction between 2; D 1~ D 4 is the rectifier diode; C F It is a filter capacitor; R L It is the load resistor; U o and I o It refers to the DC output voltage and current; Z 1 is the decoupling impedance.

[0020] Let the primary coil be offset along the y-direction in the diagram. Since the left and right offsets are symmetrical, we will only discuss the case where y > 0: When the transmission distance is 10cm, the curve of mutual inductance change with respect to the y-axis offset can be obtained, such as... Figure 5 As shown. Since the coil has a centrally symmetric structure, only the case where y>0 is shown. It can be seen that this method can increase the equivalent mutual inductance value during offset, thereby improving the system's anti-offset capability.

[0021] Furthermore, regardless of the polarity of the transmitting coil, the receiving coil can automatically adapt, always adding the absolute values ​​of their mutual inductance, thus improving the interoperability of the system.

[0022] when M PS1 · M PS2 When the value is less than 0, the proposed structure allows for switching the transmitting coil from a DD type to a square coil. This improves upon the shortcomings of DD coils, namely, poor resistance to offset in the y-axis direction. Figure 5 As shown, the equivalent mutual inductance was increased by 29.1%, while the traditional coil structure showed a significant decrease in mutual inductance, accompanied by the mutual inductance of a single coil crossing zero, which is quite dangerous.

[0023] To achieve the summation of the absolute values ​​of the mutual inductances, it is necessary to... M psi When the value is less than 0, the corresponding inverter switching transistor drive signal is inverted. For example, in the case of a y offset of 10cm, Mps1 <0, M ps2 >0, the inverter drive signal schematic diagram is shown as Figure 6

[0024] In order to verify the anti-offset ability of the proposed structure, simulation experiments based on LCC / S compensation topology are carried out based on Figure 4 The circuit parameters of the WPT system are shown in Table 1, wherein f is the working frequency of the transmitting circuit.

[0025] Table 1 Circuit parameters

[0026] The output voltage when the coils are aligned is shown in Figure 7 . Within the range of 10 times load change, the output voltage decreases from 64.07 V to 63.77 V, with a fluctuation rate of 0.47%, which verifies the load-independent constant voltage output characteristics of the LCC / S compensation topology.

[0027] Since the equivalent mutual inductance adopts the calculation method of absolute value summation, the method proposed by the application successfully solves the zero-crossing problem in the coupling process of multi-polarity coils, which enhances the compatibility between the coils.

[0028] Eliminating the coupling zero-crossing phenomenon also improves the safety performance of the wireless power transmission system. Taking the LCC / S compensation system with constant voltage output as an example, the zero-crossing problem occurring in the coupling process may cause the power to suddenly and sharply rise, thereby damaging the system.

[0029] Overall, the multi-coil multi-inverter topology structure proposed by the application can significantly improve the anti-offset ability and interoperability of the system.

[0030] The above describes in detail the multi-transmitting coil multi-parallel inverter wireless power transmission system with strong anti-offset ability and interoperability proposed by the application, and the principles and implementation modes of the application are described. The above description of the embodiments is only used to help understand the method of the application and its core idea; at the same time, for those skilled in the art, according to the idea of the application, the specific implementation mode and application range will be changed, and the above description of the application should not be understood as a limitation of the application.​

Claims

1. A wireless power transfer system for multi-transmitter coil multi-parallel inverters with strong anti-offset and interoperability characteristics, characterized in that: The wireless power transmission system includes a primary-side circuit, a secondary-side circuit, and a decoupling module; The primary circuit converts direct current into multiple alternating currents to drive at least two transmitting coils; The secondary circuit receives electrical energy through a single receiving coil, which is then rectified and supplied to the load. The secondary circuit has no additional decoupling device. The decoupling module achieves electromagnetic decoupling between the transmitting coils through passive impedance elements, enabling the system to meet the equivalent mutual inductance requirement. ,in M PS It is the original equivalent mutual inductance of the secondary side. M Pi It is the receiving coil and the transmitting coil. i Mutual attraction between them.

2. The wireless power transmission system according to claim 1, characterized in that: The passive impedance element is an inductor or capacitor, connected between the transmitting coil branches to achieve electromagnetic decoupling between the transmitting coils.

3. The wireless power transmission system according to claim 2, characterized in that: The primary-side circuit includes at least two sets of transmitting circuits, each set consisting of a half-bridge inverter and a compensation inductor. L fn Compensation capacitor C fn Compensation capacitor C n and transmitting coil L n composition; All transmitting branches share a common DC input voltage. U in and capacitor C in ; Different transmitting branches are connected by passive impedance elements.

4. The wireless power transmission system according to claim 3, characterized in that: The half-bridge inverter includes two switching transistors.

5. The wireless power transmission system according to claim 1, characterized in that: The secondary circuit includes a single receiving coil and a compensation capacitor. C p A full-bridge rectifier consisting of four rectifier diodes, and a filter capacitor. C F and load resistance R L .

6. The wireless power transmission system according to claim 1, characterized in that: The wireless power transmission system also includes a control module. The control module dynamically adjusts the phase of the drive signal according to the polarity of the receiving coil and the mutual inductance with each transmitting coil, and reverses the phase of the drive signal by changing the timing of the inverter switching transistors.

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