An electric vehicle wireless charging system with power level interoperability

Abstract

The application provides a wireless charging system for electric vehicles with power level interoperability, comprising two charging channels, channel 1 adopts a single-pole coil, channel 2 adopts a double-pole coil, the coils of the two charging channels form a cross-arranged coupling structure; the transmitting end adopts an inverter composed of four switch tubes; the two ends of channel 1 are respectively connected between switch tube S1 and switch tube S2 and between switch tube S3 and switch tube S4 of the inverter; the two ends of channel 2 are respectively connected between switch tube S1 and switch tube S2 of the inverter and the negative pole of the power supply; the receiving end adopts three groups of parallelly-connected half-bridges uncontrolled rectifiers; 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. By changing the conduction state of the four switch tubes of the transmitting end, four different levels of output power can be realized without changing the input voltage.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wireless charging, and particularly relates to a wireless charging system for electric vehicles with power level interoperability. BACKGROUND

[0002] The main charging mode for electric vehicles is wired charging using charging piles. Although this charging mode is simple and efficient, it still has great limitations, such as the possibility of contact sparks at the contact head and the possibility of exposed transmission lines. Therefore, how to solve the above safety problems has become a hot research topic for electric vehicles.

[0003] Wireless power transfer (WPT) technology mainly includes magnetic field coupling, electric field coupling, and wireless electric waves. It overcomes the shortcomings of traditional wired power supply methods, such as the generation of electric contact sparks, aging and wear, and poor convenience. It has the advantages of high reliability and good flexibility. In the charging standard of electric vehicle wireless charging, the charging power is divided into WPT1 (<3.70kW), WPT2 (2.96-7.70kW), and WPT3 (6.16-11.10kW) three levels. In the WPT field, in order to realize the output of multiple powers, additional switching tubes are often added, the system frequency is changed, the equivalent load is changed, and synchronous rectification is used. The above-mentioned methods reduce the degree of 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

[0004] In view of the defects and deficiencies of the prior art, in order to realize the output of multiple power levels under the same output while ensuring the degree of freedom of WPT system design and the robustness of the system, the application provides a wireless charging system for electric vehicles with power level interoperability, which can realize wireless power transfer of WPT1-3 three power levels without adding other additional switches. By changing the switching states of switching tubes S1-S4, four different output power levels are further realized. Different conduction states of S1-S4 correspond to different magnetic coupling structure working states, and the double-channel energy transmission formed by the system can further realize four different WPT output power levels to meet the interoperability performance of different power levels under multiple air gaps.

[0005] The technical solution adopted by the application to solve its technical problems is:

[0006] A power level interoperable electric vehicle wireless charging system: comprising two charging channels, channel 1 adopts a single-pole coil, channel 2 adopts a double-pole coil, and the coils of the two charging channels form a cross-arranged coupling structure;

[0007] The transmitting end adopts an inverter composed of four switch tubes; the two ends of channel 1 are respectively connected between switch tube S1 and switch tube S2 and between switch tube S3 and switch tube S4 of the inverter; and the two ends of channel 2 are respectively connected between switch tube S1 and switch tube S2 and the negative electrode of the power supply of the inverter;

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

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

[0010] Without changing the input voltage and the transmission distance, four different output power levels are realized by changing the switching states of switch tubes S1-S4.

[0011] When the system works in mode one, switch tube S1 and switch tube S2 are in the always-on state, and switch tube S3 and switch tube S4 are in the complementary state.

[0012] When the system works in mode two, switch tube S3 and switch tube S4 are in the always-on state, and switch tube S1 and switch tube S2 are in the complementary state.

[0013] When the system works in mode three, switch tube S3 is in the always-on state, switch tube S4 is in the always-closed state, and switch tube S1 and switch tube S2 are in the complementary state,

[0014] When the system works in mode four, switch tube S1 and switch tube S4 are in the same phase conduction, switch tube S2 and switch tube S3 are in the same phase conduction, switch tube S1 and switch tube S2 are in the complementary state, and switch tube S3 and switch tube S4 are in the complementary state.

[0015] Compared with the prior art, the prominent features and advantages of the present application and the preferred scheme thereof at least include:

[0016] (1) The system does not need to use additional switches, thereby saving the cost and the circuit board layout space;

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

[0018] (3) The system has high freedom, i.e. the shape of the transmitting and receiving coils is not limited, and the anti-deviation characteristic can be achieved to a certain extent by changing different magnetic coupling structures. BRIEF DESCRIPTION OF DRAWINGS

[0019] The application will be described in further detail below with reference to the drawings and specific embodiments:

[0020] Figure 1 A circuit structure diagram of the electric vehicle wireless charging system with power level interoperability according to the embodiment of the application;

[0021] Figure 2 A magnetic coupling structure diagram according to the embodiment of the application;

[0022] Figure 3 A mode 1 state circuit structure diagram of the WPT system according to the embodiment of the application;

[0023] Figure 4 A mode 2 state circuit structure diagram of the WPT system according to the embodiment of the application;

[0024] Figure 5 A mode 3 state circuit structure diagram of the WPT system according to the embodiment of the application;

[0025] Figure 6 A mode 4 state circuit structure diagram of the WPT system according to the embodiment of the application. DETAILED DESCRIPTION

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

[0027] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in the specification have the same meaning as 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 the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should be understood that when the terms "comprise" and / or "include" are used in the specification, there is a feature, step, operation, device, component and / or combination thereof.

[0029] The embodiment of the application will be specifically introduced as follows:

[0030] The embodiment of the application proposes an electric vehicle wireless charging system with power level interoperability, such as Figure 1As shown, it includes two charging channels, channel 1 adopts a single-pole coil, channel 2 adopts a double-pole coil, the coils of the two charging channels constitute a coupling structure as shown in Figure 2 .

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

[0032] The receiving end adopts three groups of parallel half-bridge uncontrolled rectifiers; 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] But it needs to be explained that the structure proposed in the application is not limited to the LCC compensation network as shown in Figure 1 , but can also be adapted to a variety of simple or complex compensation networks. The transmitting end (Tx) and the receiving end (Rx) in the structure of the application are single-pole and double-pole coil structures, and the coupling structure presented is as shown in Figure 2 . The coupling structure adopted in the application is not limited to single-pole and double-pole coil structures. The coils do not limit the overall size (l1 and l2), and do not limit the number of turns, the winding method, the air gap (h1 and h2), and the winding material, and can be wound with Litz wire or integrated into a planar PCB board.

[0034] Based on the above structure, by changing the switching states of switch tubes S1-S4, the embodiment further realizes four different output power levels, and the time sequence states of the switch tubes corresponding to each mode and the corresponding circuit topologies are as shown in Figures 3-6 . Different conduction states of S1-S4 correspond to different magnetic coupling structure working states, and in combination with the double-channel energy transmission composed of the 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 one state

[0036] The self-inductance of the transmitting and receiving coils contained in the proposed WPT system can be defined as L T1 , L T2 , L R1 and L R2 . L F1 and L F2 are compensation inductances. C F1 , C F2 , C T1 , C T2 , CR1 and C R2 is the compensation capacitor. For simplicity of the subsequent description, it is defined that M1 is greater than M2, so in mode one, the formed circuit topology, switching sequence and equivalent circuit are shown in Figure 3 , where V INV (V L ) and U T1 (U R ) are the inverse (rectified) DC voltage and fundamental AC voltage, respectively. R EQ is the equivalent load resistance. They can be expressed as:

[0037]

[0038] The resonance relationship presented by the system at the resonance frequency can be expressed as:

[0039]

[0040] In mode one, the switching tubes S1 and S2 are in the always-on state, and S3 and S4 are in the complementary state. At this time, the transmitting ends L T1 and L T2 are in series connection, and based on Kirchhoff's voltage law (KVL), it can be further obtained that the final output power is expressed as:

[0041]

[0042] (2) Mode two state

[0043] In mode two, the formed circuit topology, switching sequence and equivalent circuit are shown in Figure 4 .

[0044] In mode two, the switching tubes S3 and S4 are in the always-on state, and S1 and S2 are in the complementary state. In this mode, only L T2 is the transmitting coil, and since there is no additional cross-coupling between the transmitting and receiving coils, based on KVL, the final output power can be expressed as:

[0045]

[0046] (3) Mode three state

[0047] In mode three, the formed circuit topology, switching sequence and equivalent circuit are shown in Figure 5 .

[0048] In mode three, the switching tube S3 is in the always-on state, the switching tube S4 is in the always-closed state, and S1 and S2 are in the complementary state. In this mode, the transmitting ends L T1 and L T2Equivalent to parallel connection state, while receiving end L R1 and L R2 Equivalent to series connection state, based on KVL further can get the final output power expression as:

[0049]

[0050] (4) Mode four state

[0051] In mode four, the circuit topology formed, switch timing and equivalent circuit as shown in Figure 6 , wherein U T2 is the fundamental AC voltage, which can be expressed as:

[0052]

[0053] In mode four, switch S1 and S4 in phase conduction, switch S2 and S3 in phase conduction, and S1 and S2 in complementary state, S3 and S4 in complementary state. In this mode, L T1 works in full bridge mode, L T2 works in half bridge mode, while receiving end L R1 and L R2 Equivalent to series connection state. Based on KVL further can get the final output power expression as:

[0054]

[0055] It should be noted that unless otherwise defined, the technical terms or scientific terms used in the present application should be understood as the usual meaning understood by those skilled in the art to which the present application belongs. The "first", "second" and similar words used in the present application do not represent any order, quantity or importance, but are only used to distinguish different components. "Include" or "contain" and similar words mean that the elements or objects before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connected" or "connected" and similar words are not limited to physical or mechanical connection, but can include electrical connection, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to represent relative positional relationship, when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0056] The present patent is not limited to the above best mode, anyone can derive other various forms of a power level interoperable electric vehicle wireless charging system under the inspiration of the present patent, any equivalent changes and modifications made within the scope of the present patent application shall be covered by the present patent.

Claims

1. A wireless electric vehicle charging system with power level interoperability, characterized by: Two charging channels are included, channel 1 adopts a single-pole coil, and channel 2 adopts a double-pole coil; the coils of the two charging channels form a cross-arranged coupling structure; The transmitting end adopts an inverter composed of four switch tubes; the two ends of channel 1 are respectively connected between switch tube S1 and switch tube S2 and between switch tube S3 and switch tube S4 of the inverter; the two ends of channel 2 are respectively connected between switch tube S1 and switch tube S2 and between the negative electrode of the power supply of the inverter; The receiving end adopts three groups of half-bridge uncontrolled rectifiers 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; Without changing the input voltage and transmission distance, four different output power levels are realized by changing the switching states of switch tubes S1-S4; When the system works in mode one, switch tubes S1 and S2 are in the always-on state, and switch tubes S3 and S4 are in the complementary state; When the system works in mode two, switch tubes S3 and S4 are in the always-on state, and switch tubes S1 and S2 are in the complementary state; When the system works in mode three, switch tube S3 is in the always-on state, switch tube S4 is in the always-off state, and switch tubes S1 and S2 are in the complementary state; When the system works in mode four, switch tubes S1 and S4 are in the same phase conduction, switch tubes S2 and S3 are in the same phase conduction, switch tubes S1 and S2 are in the complementary state, and switch tubes S3 and S4 are in the complementary state.

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

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