Electric vehicle wireless charging system with power level interoperability

Abstract

The invention provides an electric vehicle wireless charging system with power level interoperability, which comprises two charging channels, the channel 1 adopts a monopole coil, the channel 2 adopts a bipolar coil, and the coils of the two charging channels form a cross-arranged coupling structure; the transmitting end adopts an inverter formed by four switching tubes; two ends of the channel 1 are respectively connected between a switch tube S1 and a switch tube S2 of the inverter and between a switch tube S3 and a switch tube S4; two ends of the channel 2 are respectively connected between the switch tube S1 and the switch tube S2 of the inverter and the negative electrode of the power supply; the receiving end adopts three groups of half-bridge uncontrolled rectifiers which are connected in parallel; two ends of the channel 1 are respectively connected between the first half bridge and the second half bridge; and two ends of the channel 2 are respectively connected between the second half bridge and the third half bridge. By changing the conducting states of the four switching tubes of the transmitting end, four different levels of output power can be realized on the premise of not changing the input voltage.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless charging, and in particular relates to an electric vehicle wireless charging system with power level interoperability. Background Art

[0002] The main way to charge electric vehicles is to use charging piles for wired charging. Although this charging method is simple and efficient, it still has major limitations, such as the possibility of contact sparks at the contact head and the possibility of exposure of the transmission line. Therefore, how to solve the above safety issues has become a hot topic in the research of electric vehicles.

[0003] Wireless Power Transfer (WPT) technology mainly includes magnetic field coupling, electric field coupling, radio waves and other methods. Because it overcomes the shortcomings of traditional wired power supply methods such as easy to generate electrical contact sparks, aging and wear, and poor convenience, it has the advantages of high reliability and good flexibility. In the charging standards in the field of wireless charging of electric vehicles, they are divided into three levels according to the charging power: WPT1 (<3.70kW), WPT2 (2.96~7.70kW) and WPT3 (6.16~11.10kW). In the field of WPT, in order to achieve the output of multiple powers, methods such as adding additional switching tubes, changing the system frequency, changing the equivalent load and synchronous rectification are often used. The above-mentioned methods reduce the freedom of system design, increase the difficulty of system maintenance, and reduce the robustness of the system under the premise of meeting multiple output power levels. Summary of the invention

[0004] In view of the defects and shortcomings of the existing technical solutions, in order to achieve the output of multiple power levels under the same output, while ensuring the freedom of design of the WPT system itself and the robustness of the system, the present invention proposes an electric vehicle wireless charging system with power level interoperability, that is, it can achieve wireless power transmission of three power levels of WPT1 to 3 without adding other additional switches. By changing the switch state of the switch tubes S1 to S4, four different output power levels can be further achieved. The different conduction states of the S1 to S4 switches correspond to different working states of the magnetic coupling structure, and combined with the dual-channel energy transmission composed of the proposed system, four different WPT output power levels can be further achieved, thereby meeting the interoperability performance of different power levels under multiple air gaps.

[0005] The technical solution adopted by the present invention to solve the technical problem is:

[0006] An electric vehicle wireless charging system with power level interoperability includes two charging channels, channel 1 uses a monopolar coil, channel 2 uses a bipolar coil, and the coils of the two charging channels form a cross-arranged coupling structure;

[0007] The transmitting end uses an inverter composed of 4 switching tubes; the two ends of channel 1 are respectively connected between the switching tube S1 and the switching tube S2 of the inverter, and between the switching tube S3 and the switching tube S4; the two ends of channel 2 are respectively connected between the switching tube S1 and the switching tube S2 of the inverter, and the negative pole of the power supply;

[0008] The receiving end uses three groups of half-bridge uncontrolled rectifiers connected in parallel; the two ends of channel 1 are respectively connected between the first half bridge and the second half bridge; the two ends of channel 2 are respectively connected between the second half bridge and the third half bridge.

[0009] The two charging channels are respectively provided with two corresponding compensation networks.

[0010] Under the premise of not changing the input voltage and transmission distance, four different output power levels can be achieved by changing the switching states of the switch tubes S1 to S4.

[0011] When the system works in mode 1, the switch tube S1 and the switch tube S2 are in a normally open state, and the switch tube S3 and the switch tube S4 are in a complementary state.

[0012] When the system works in mode 2, the switch tube S3 and the switch tube S4 are in a normally open state, and the switch tube S1 and the switch tube S2 are in a complementary state.

[0013] When the system works in mode 3, the switch tube S3 is in the normally open state, the switch tube S4 is in the normally closed state, and the switch tubes S1 and S2 are in the complementary state.

[0014] When the system works in mode 4, the switch tubes S1 and S4 are turned on in phase, the switch tubes S2 and S3 are turned on in phase, and the switch tubes S1 and S2 are in a complementary state, and the switch tubes S3 and S4 are in a complementary state.

[0015] Compared with the prior art, the outstanding features and advantages of the present invention and its preferred embodiments include at least:

[0016] (1) The proposed system does not require the use of additional switches, saving costs and circuit board layout space;

[0017] (2) The proposed system can achieve four different power outputs under the premise of a fixed input voltage, and can adapt to four different levels of output power under multiple fixed air gaps;

[0018] (3) The proposed system has a very high degree of freedom, that is, it does not restrict the shapes of the transmitting and receiving coils, and can have a certain degree of anti-offset characteristics by changing different magnetic coupling structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0020] Figure 1 This is a circuit structure diagram of an electric vehicle wireless charging system with power level interoperability according to an embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram of the magnetic coupling structure of an embodiment of the present invention;

[0022] Figure 3 This is a circuit structure diagram of mode 1 of the WPT system according to an embodiment of the present invention;

[0023] Figure 4 This is a circuit structure diagram of mode 2 of the WPT system according to an embodiment of the present invention;

[0024] Figure 5 This is a circuit structure diagram of the three-state mode of the WPT system provided in an embodiment of the present invention;

[0025] Figure 6 This is a circuit structure diagram of the four-state mode of the WPT system proposed in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the features and advantages of this patent more obvious and easy to understand, the following embodiments are specifically described in detail as follows:

[0027] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in this specification have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0028] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0029] The embodiment of the present invention specifically introduces the solution as follows:

[0030] The embodiment of the present invention provides an electric vehicle wireless charging system with power level interoperability, such as Figure 1As shown, it includes two charging channels, channel 1 uses a unipolar coil, channel 2 uses a bipolar coil, and the coils of the two charging channels are constructed as shown in FIG. Figure 2 The cross-arranged coupling structure shown;

[0031] The transmitting end uses an inverter composed of 4 switching tubes; the two ends of channel 1 are respectively connected between the switching tube S1 and the switching tube S2 of the inverter, and between the switching tube S3 and the switching tube S4; the two ends of channel 2 are respectively connected between the switching tube S1 and the switching tube S2 of the inverter, and the negative pole of the power supply;

[0032] The receiving end uses three groups of half-bridge uncontrolled rectifiers connected in parallel; the two ends of channel 1 are respectively connected between the first half bridge and the second half bridge; the two ends of channel 2 are respectively connected between the second half bridge and the third half bridge.

[0033] However, it should be noted that the structure of the present invention is not limited to Figure 1 The LCC compensation network shown can also be adapted using a variety of simple or complex compensation networks. The transmitting end (Tx) and the receiving end (Rx) in the structure of the present invention are monopolar and bipolar coil structures, and the coupling structure presented is as follows Figure 2 As shown, the coupling structure used in the present invention is not limited to monopolar and bipolar coil structures. The coil used is not limited to the overall size (l1 and l2), and is not limited to the number of coil turns, winding method, air gap (h1 and h2) and winding material. It can be wound with Litz wire or integrated into a flat PCB board.

[0034] Based on the above structure, by changing the switch states of the switch tubes S1 to S4, this embodiment further realizes four different output power levels. The timing states of the switch tubes corresponding to each mode and the corresponding circuit topologies are as follows: Figures 3 to 6 As shown in the figure, the different conduction states of the S1~S4 switches correspond to different working states of the magnetic coupling structure, and combined with the dual-channel energy transmission composed of the proposed system, four different WPT output power levels can be further realized to meet the interoperability performance of different power levels under various air gaps.

[0035] (1) Mode 1

[0036] The self-inductance of the transmitting and receiving coils included in the proposed WPT system can be defined as L T1 , L T2 , L R1 and L R2 .L F1 and L F2 To compensate the inductance. C F1 , C F2 , C T1 , C T2 , CR1 and C R2 For the convenience of subsequent description, M1 is defined as greater than M2. Therefore, in the following mode, the circuit topology, switching timing and equivalent circuit are as follows: Figure 3 As shown, V INV (V L ) and U T1 (U R ) are the inverter (rectifier) ​​DC voltage and the fundamental AC voltage respectively. EQ is the equivalent load resistance. They can be expressed as:

[0037]

[0038] The resonant relationship of the system at the resonant frequency can be expressed as:

[0039]

[0040] In mode 1, the switch tubes S1 and S2 are in the normally open state, and S3 and S4 are in the complementary state. T1 and L T2 In the series connection state, based on Kirchhoff's voltage law (KVL), the final output power can be further expressed as:

[0041]

[0042] (2) Mode 2 status

[0043] In mode 2, the circuit topology, switching timing and equivalent circuit are as follows: Figure 4 shown.

[0044] In mode 2, the switches S3 and S4 are in the normally open state, and S1 and S2 are in the complementary state. T2 is the transmitting coil. Since there is no additional cross-coupling between the transmitting and receiving coils, the final output power can be expressed as:

[0045]

[0046] (3) Mode 3

[0047] In mode 3, the circuit topology, switching timing and equivalent circuit are as follows: Figure 5 shown.

[0048] In mode 3, switch tube S3 is in the normally open state, switch tube S4 is in the normally closed state, and S1 and S2 are in the complementary state. T1 and L T2It is equivalent to a parallel connection state, and the L at the receiving end R1 and L R2 Equivalent to a series connection state, based on KVL, the final output power can be further expressed as:

[0049]

[0050] (4) Mode 4 state

[0051] In mode 4, the circuit topology, switching timing and equivalent circuit are as follows: Figure 6 As shown, U T2 is the fundamental AC voltage, which can be expressed as:

[0052]

[0053] In mode 4, switch tubes S1 and S4 are turned on in phase, switch tubes S2 and S3 are turned on in phase, and S1 and S2 are in a complementary state, and S3 and S4 are in a complementary state. T1 Working in full-bridge mode, L T2 Working in half-bridge mode, the receiving end L R1 and L R2 It is equivalent to a series connection state. Based on KVL, the final output power can be further expressed as:

[0054]

[0055] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0056] This patent is not limited to the above-mentioned best implementation mode. Anyone can derive other forms of an electric vehicle wireless charging system with power level interoperability under the inspiration of this patent. All equal changes and modifications made according to the scope of the patent application of the present invention should be covered by this patent.

Claims

1. An electric vehicle wireless charging system with power level interoperability, characterized in that: It includes two charging channels, channel 1 uses a monopolar coil, channel 2 uses a bipolar coil, and the coils of the two charging channels form a cross-arranged coupling structure; The transmitting end uses an inverter composed of 4 switching tubes; the two ends of channel 1 are respectively connected between the switching tube S1 and the switching tube S2 of the inverter, and between the switching tube S3 and the switching tube S4; the two ends of channel 2 are respectively connected between the switching tube S1 and the switching tube S2 of the inverter, and the negative pole of the power supply; The receiving end uses three groups of half-bridge uncontrolled rectifiers connected in parallel; the two ends of channel 1 are respectively connected between the first half bridge and the second half bridge; the two ends of channel 2 are respectively connected between the second half bridge and the third half bridge.

2. The electric vehicle wireless charging system with power level interoperability according to claim 1, characterized in that: The two charging channels are respectively provided with two corresponding compensation networks.

3. The electric vehicle wireless charging system with power level interoperability according to claim 1, characterized in that: Without changing the input voltage and transmission distance, four different output power levels can be achieved by changing the switching states of the switch tubes S1~S4.

4. An electric vehicle wireless charging system with power level interoperability according to any one of claims 1-3, characterized in that: When the system works in mode 1, the switch tube S1 and the switch tube S2 are in a normally open state, and the switch tube S3 and the switch tube S4 are in a complementary state.

5. An electric vehicle wireless charging system with power level interoperability according to any one of claims 1-3, characterized in that: When the system works in mode 2, the switch tube S3 and the switch tube S4 are in a normally open state, and the switch tube S1 and the switch tube S2 are in a complementary state.

6. An electric vehicle wireless charging system with power level interoperability according to any one of claims 1-3, characterized in that: When the system works in mode three, the switch tube S3 is in a normally open state, the switch tube S4 is in a normally closed state, and the switch tubes S1 and S2 are in a complementary state.

7. An electric vehicle wireless charging system with power level interoperability according to any one of claims 1-3, characterized in that: When the system works in mode 4, the switch tubes S1 and S4 are turned on in phase, the switch tubes S2 and S3 are turned on in phase, and the switch tubes S1 and S2 are in a complementary state, and the switch tubes S3 and S4 are in a complementary state.

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