Modularized reusable solar current collection device for wireless charging of electric vehicle

Abstract

The invention provides a modularized reusable solar current collection device for wireless charging of an electric vehicle, which comprises a plurality of basic sub-modules, and each basic sub-module comprises a wireless charging module and a photovoltaic power generation module; the wireless charging module comprises a full-bridge inverter consisting of four switching tubes; one bridge arm of the full-bridge inverter is multiplexed as a switch tube and a diode of a Boost circuit of the photovoltaic power generation module; the cascade H bridges are used for expanding the cascade number of the k basic sub-modules, the k basic sub-modules are all connected with switches, the multi-stage solar current collection device is obtained, and k is larger than or equal to 2; according to the technical scheme, when solar energy is stored, the voltage between the energy storage units can be actively balanced, and the reliability of normal operation of the system is ensured. When wireless charging is carried out, an S-S compensation topology can be formed with an electric vehicle receiving end, and wireless electric energy transmission is realized.

Description

Technical Field

[0001] This invention relates to the field of wireless charging technology for electric vehicles, and in particular to a modular and reusable solar power collection device for wireless charging of electric vehicles. Background Technology

[0002] With the continuous development of economic globalization, environmental pollution and energy shortages have become critical global issues that urgently need to be addressed. Electric vehicles, freed from dependence on fossil fuels, have attracted significant attention due to their zero emissions and low operating costs. Furthermore, compared to traditional wired charging facilities, wireless charging technology (WPT) requires no physical connection, offering a safer and more convenient charging experience, and is widely used in the electric vehicle sector. However, the large-scale integration of electric vehicle charging stations poses serious challenges to power grid quality and equipment operation. In contrast to the power grid, photovoltaic (PV) systems require no additional power conversion equipment and can be directly utilized as direct current (DC) energy. The combination of PV and WPT can be applied to various application scenarios, including electric vehicle charging, realizing the entire process from power generation, transmission, to distribution, and has promising application prospects.

[0003] Currently, integrated PV and WPT systems often include two stages of power conversion: a DC-DC converter for maximum power point tracking (MPPT) and a compensation network for wireless power transfer. This leads to increased component losses and reduced system efficiency. To address this issue, some literature proposes an integrated system with a hybrid MPPT control strategy. This system achieves maximum efficiency point tracking (MEPT) by adjusting the conduction angle of the semi-active rectifier and MPPT by adjusting the conduction angle of the inverter. Other approaches integrate a boost MPPT controller with a high-frequency T-type inverter, providing various voltage conversion gains. However, these systems use photovoltaics as the input source, and their power output is significantly affected by environmental factors, exhibiting uncertainty.

[0004] Integrating photovoltaic systems with battery storage can alleviate this problem and improve the overall system reliability, such as... Figure 1 As shown, when photovoltaic power supply exceeds expectations, the photovoltaic system primarily powers the downstream circuits, with some of the energy used to charge the battery via a bidirectional DC-DC converter. When photovoltaic power supply is insufficient, the energy storage system provides power. However, this system involves multiple circuit stages, resulting in a complex structure and low integration.

[0005] Furthermore, when multiple energy sources, such as photovoltaics, energy storage, and the power grid, are integrated into the system, a reasonable power control strategy is needed to resolve conflicts between them. However, existing power control strategies achieve continuous operation of the integrated system by controlling power flow, which still requires additional power conversion equipment. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a modular, reusable solar energy collection device for wireless charging of electric vehicles. During solar energy storage, it can actively balance the voltage between energy storage units to ensure the reliability of normal system operation. During wireless charging, it can form an SS-compensated topology with the electric vehicle receiver to achieve wireless power transmission.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a modular reusable solar collector for wireless charging of electric vehicles, comprising multiple basic sub-modules, wherein the basic sub-modules include a wireless charging module and a photovoltaic power generation module; the wireless charging module includes a full-bridge inverter composed of four switching transistors; one arm of the full-bridge inverter is reused as the switching transistor and diode of the Boost circuit of the photovoltaic power generation module; to use a cascaded H-bridge... k By expanding the number of cascaded basic sub-modules, and ensuring that each is connected to a switch, a multi-stage solar collector is obtained. k ≥2; The wireless charging module includes a first switching transistor S 1,k Second switch S 2,k Third switch S 3,k and the fourth switch S 4,k During the daytime, the switch is turned on, the first k Each basic submodule controls the first switching transistor S. 1,k Second switch S 2,k Charge the battery pack while controlling the third switch S 3,k and the fourth switch S 4,k To balance the voltage between basic sub-modules, solar energy is stored. At night, when the switch is turned off, the solar collector and the electric vehicle receiver form an SS compensation topology for the wireless charging module. The battery pack of the solar collector acts as a DC input source to charge the load battery of the electric vehicle.

[0008] In a preferred embodiment, in wireless charging mode, the SS equivalent circuit includes the self-inductance of the transmitting coil. L T The self-inductance of the receiving coil L R Transmitter compensation capacitor C T Receiver compensation capacitor C R and the mutual inductance between coils M TR When the first switching transistor S 1,k Fourth switch S 4,k The second switch S is turned on. 2,k Third switch S 3,k When shut down, the first kOutput of each basic submodule U Bk When the second switch S 2,k Third switch S 3,k The first switch S is on. 1,k Fourth switch S 4,k When shut down, the first k Output of each basic submodule— U Bk If the cascaded H-bridge CHB has n Each basic submodule can output m Level ( n When it is even, m = n ; n When it is an odd number, m = ( n +1), In phase-shift carrier modulation, all triangular carriers have the same amplitude and frequency, and the phase difference between any two adjacent carriers is 360° / n .

[0009] In a preferred embodiment, in photovoltaic power generation mode, the first... k Each basic submodule includes a synchronous rectification boost circuit, consisting of a first switching transistor S. 1,k Second switch S 2,k An inductor L k Voltage source U Bk Voltage source U PVk It consists of two capacitors; the first k Each basic submodule controls the first switching transistor S. 1,k Second switch S 2,k This is to enable MPPT to charge the battery pack.

[0010] In a preferred embodiment, for the first k -1 basic submodule and the first k The basic sub-modules perform equalization control in four stages: (1) Stage a: Inductor current i T lower limit I min Inductor current i T Inductor current i T upper limit I max U Bk-1 Through S1,k-1 S 4,k-1 S 1,k and S 3,k Self-inductance of the transmitting coil L T Charging causes inductor current to flow. i T It increases linearly, while U Bk-1 Reduce; at this time, U Bk Self-inductance of the transmitting coil L T Continuation path; (2) Stage b: Inductor current i T ≥ Inductor current i T upper limit I max Inductor current i T The amplitude increases to its maximum value, causing S to... 4,k-1 Off, S 3,k-1 Activation; U Bk-1 The discharge path is cut off, and the inductor current... i T Remain unchanged; (3) Stage c: Inductor current i T lower limit I min Inductor current i T Inductor current i T upper limit I max S 2,k-1 and S 2,k Activated under MPPT control, while S 1,k-1 and S 1,k Turn off; changes in the switching state of adjacent bridge arms cause S 4,k-1 Activation, S 3,k-1 Off; self-inductance of the transmitting coil L T Through S 2,k-1 S 4,k-1 S 2,k and S 3,k right U Bk Charging causes inductor current to flow. i T Linear decrease, U Bk Increase; (4) Stage d: Inductor current i T ≤Inductor current i T lower limit I min Inductor current i T The amplitude of S decreases to its minimum value, causing S to... 3,k Off, S 4,k Activation; U Bk The charging path is interrupted, and the inductor current... i T The basics remain unchanged.

[0011] Compared with the prior art, the present invention has the following beneficial effects: 1. Improved voltage balancing performance: Overcomes the limitations of modular multilevel converters or cascaded H-bridge balancing capacity, ensuring voltage balance between sub-modules even under conditions of large battery voltage variations.

[0012] 2. Fewer switching devices: No additional power conversion equipment is needed to control the flow of power, reducing the number of switching devices and lowering device costs. Attached Figure Description

[0013] Figure 1 A schematic diagram of a traditional photovoltaic energy storage wireless charging structure; Figure 2 The diagram shows commonly used circuit topologies for different systems in preferred embodiments of the present invention; wherein, (a) represents wireless charging, (b) represents photovoltaic power generation, and (c) represents an integrated system. Figure 3 This is a schematic diagram of the circuit topology of a preferred embodiment of the present invention; Figure 4 This is a schematic diagram of the SS equivalent circuit of a preferred embodiment of the present invention; Figure 5 This is a schematic diagram of carrier phase-shift modulation according to a preferred embodiment of the present invention; Figure 6 This is a circuit topology diagram of a solar collector device according to a preferred embodiment of the present invention; Figure 7 This is a schematic diagram of the operation process of the equalization circuit according to a preferred embodiment of the present invention; Figure 8 This is a schematic diagram of the operating waveforms of the equalization circuit according to a preferred embodiment of the present invention; Figure 9 This is a control block diagram of a preferred embodiment of the present invention. Detailed Implementation

[0014] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0015] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0016] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application; as used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise; furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0017] This invention combines a photovoltaic power generation circuit and a wireless charging inverter circuit into one through module reuse, resulting in a basic sub-module (SM) for a solar collector, such as... Figure 2 As shown. Among them, Figure 2 (a) and Figure 2 (b) shows the common topologies for wireless charging and photovoltaic power generation, respectively. One arm of the full-bridge inverter in a wireless charging system can be reused as the switching transistor and diode in the Boost circuit of a photovoltaic power generation system to achieve integration of the two systems, such as... Figure 2 As shown in (c).

[0018] To increase the storage capacity and voltage level of the solar collector, a cascaded H-bridge is used to expand the number of cascaded submodules, resulting in a multi-stage solar collector, such as... Figure 3 As shown.

[0019] The circuit topology works as follows: During the day, switch K is turned on. k Submodules (SM #) k Control S 1,k and S 2,k MPPT charges the battery pack while controlling S 3,k and S 4,k Solar energy is stored by balancing the voltage between submodules. At night, switch K is turned off, and the solar collector and the electric vehicle receiver can form an SS-compensated topology for a wireless charging system. The device's battery pack acts as a DC input source to charge the electric vehicle's load battery. At this time, the photovoltaic array does not affect operation.

[0020] If charging of the electric vehicle is required during the day, switch K will be turned off. In this mode, the device supports simultaneous photovoltaic power generation and wireless charging, although the photovoltaic array is not operating on its MPP.

[0021] (a) Wireless charging mode The solar energy stored in this topology can be used in wireless charging systems for electric vehicles, and the relevant equivalent circuit is as follows: Figure 4 As shown. Among them. L T ( L R ( ) represents the self-inductance of the transmitting (receiving) coil. C T ( C R () is a compensation capacitor. M TR This refers to the mutual inductance between coils. u T This provides the fundamental component of the AC output voltage for the CHB. The CHB can achieve multi-level output characteristics through specific switching combinations, thereby effectively reducing the total harmonic distortion (THD) and improving the input power factor. When S... 1,k S 4,k On and S 2,k S 3,k When shut down, SM # k Output U Bk When S 2,k S 3,k On and S 1,k S 4,k When shut down, SM # k Output — U Bk If the cascaded H-bridge CHB has n Each basic submodule can output m Level ( n When it is even, m = n ; n When it is an odd number, m = ( n +1), In phase-shift carrier modulation, all triangular carriers have the same amplitude and frequency, and the phase difference between any two adjacent carriers is 360° / n .

[0022] Taking four-level as an example, Figure 5 This is a schematic diagram of carrier modulation. The diagram shows... v m It is a sinusoidal modulated wave, carrier wave. v k Used to generate S in the module 1,k The switching transistor drive signal, where S 1,k With S 4,k In phase, S 2,k and S 3,k That's also true. S 1,kWith S 2,k They are 180° out of phase and both have a duty cycle of 50% (not considering dead zones).

[0023] Figure 4 The system employs an SS compensation topology, whose output current is inversely proportional to the mutual inductance and independent of the parameters of other coils and the load, thus enabling constant output current. This topology maintains high power even under deviation conditions, making it suitable for the high-power operating environments of electric vehicle charging.

[0024] (II) Photovoltaic power generation mode Figure 6 The equivalent circuit of this topology when used for solar energy storage is shown, where CHB's SM # k It includes a synchronous rectification boost circuit. It consists of a switch (S... 1,k S 2,k ), an inductor ( L k Two voltage sources ( U Bk , U PVk It consists of 100 capacitors and 2 capacitors. SM # k It can be controlled by S 1,k and S 2,k MPPT is used to charge the battery. Due to the different internal parameters of each SM and photovoltaic array, the battery voltage will be different, that is, the value of the state of charge (SOC) of the battery pack will be inconsistent. This will cause the following problems: (1) the battery pack will be overcharged or over-discharged, increasing the risk of equipment damage and shortening its service life; (2) the overall performance of the current collector will decline, such as reduced energy conversion efficiency and slower response speed; (3) the current collector will exhibit the "weakest link" effect, resulting in the battery pack capacity not being fully utilized. Therefore, in order to ensure the reliability of the system's normal operation, it is necessary to perform equalization control.

[0025] To simplify the analysis, the equivalent circuit diagrams of the two SM balanced circuits are as follows: Figure 7 As shown, where U B1 > U B2 .Will i T Defined as inductor current, i B1 and i B2 Defined as flowing through L T The current values ​​of the upper and lower batteries in the branch. I min and I max Representi T The lower and upper limits. The direction indicated by the dashed arrow is the actual direction of current flow at the end of the mode. Based on the current state, the operation of the balancing circuit can be mainly divided into four stages: (1) Stage a: I min < i T < I max U B1 Through S 1,1 S 4,1 S 1,2 and S 3,2 right L T Charging caused i T It increases linearly, while U B1 Reduce. At this time, U B2 quit L T Continuation path.

[0026] (2) Stage b: i T ≥ I max i T The amplitude increases to its maximum value, causing S to... 4,1 Off, S 3,1 It is now open. U B1 The discharge path was cut off. i T The basics remain unchanged.

[0027] (3) Stage c: I min < i T < I max S 2,1 and S 2,2 Activated under MPPT control, while S 1,1 and S 1,2 Turn off. Changes in the switching state of adjacent bridge arms cause S... 4,1 Activation, S 3,1 Turn off. L T Through S 2,1 S 4,1 S 2,2 and S3,2 right U B2 Charging caused i T Linear decrease, U B2 Increase.

[0028] (4) Stage d: i T ≤ I min i T The amplitude of S decreases to its minimum value, causing S to... 3,2 Off, S 4,2 It is now open. U B2 The charging path was interrupted. i T The basics remain unchanged.

[0029] Specific working waveforms are as follows: Figure 8 As shown in the figure. i B1 The actual current direction is positive. U B1 Discharge; i B2 The actual current direction is negative. U B2 Charging. Among them, U B1 Main control S 4,1 The activation enables battery discharge, while U B2 Main control S 3,2 The activation enables battery charging. Additionally, i T The amplitude is limited to I min and I max Between, can be I min and I max The magnitude of power transmission between control modules.

[0030] Usage process or method Figure 9 This is a control block diagram of the present invention. In wireless charging mode, the first... k S in each submodule 1,k and S 4,k Driven by the same signal, S 2,k and S 3,k That's also true. S 1,k and S 2,kComplementary conduction, both with a 50% duty cycle (dead time not considered). Submodule k carrier v k After phase shifting, it is modulated by the wave. v m In comparison, the drive signal for the switching transistor is obtained.

[0031] In the photovoltaic power generation mode, the first k S in each submodule 1,k and S 2,k Complementary conduction, S 3,k and S 4,k This is also true. By controlling S 1,k and S 2,k It can implement MPPT for submodules. And S 3,k and S 4,k This is used to achieve voltage balancing between submodules. This balancing strategy is implemented using SM#. k voltage U Bk Average voltage of multiple modules U avg The comparison results determine SM# k The output state, and by adjusting I min and I max Power transmission between control modules.

Claims

1. A modular, reusable solar collector for wireless charging of electric vehicles, characterized in that, It includes multiple basic sub-modules, including a wireless charging module and a photovoltaic power generation module; the wireless charging module includes a full-bridge inverter composed of four switching transistors; one arm of the full-bridge inverter is multiplexed as the switching transistor and diode of the Boost circuit of the photovoltaic power generation module; so as to use a cascaded H-bridge. k By expanding the number of cascaded basic sub-modules, and ensuring that each is connected to a switch, a multi-stage solar collector is obtained. k ≥2; The wireless charging module includes a first switching transistor S 1,k Second switch S 2,k Third switch S 3,k and the fourth switch S 4,k During the daytime, the switch is turned on, the first k Each basic submodule controls the first switching transistor S. 1,k Second switch S 2,k Charge the battery pack while controlling the third switch S 3,k and the fourth switch S 4,k To balance the voltage between basic sub-modules, solar energy is stored. At night, when the switch is turned off, the solar collector and the electric vehicle receiver form an SS compensation topology for the wireless charging module. The battery pack of the solar collector acts as a DC input source to charge the load battery of the electric vehicle.

2. A modular, reusable solar collector for wireless charging of electric vehicles according to claim 1, characterized in that, In wireless charging mode, the SS equivalent circuit includes the self-inductance of the transmitting coil. L T The self-inductance of the receiving coil L R Transmitter compensation capacitor C T Receiver compensation capacitor C R and the mutual inductance between coils M TR When the first switching transistor S 1,k Fourth switch S 4,k The second switch S is turned on. 2,k Third switch S 3,k When shut down, the first k Output of each basic submodule U Bk When the second switch S 2,k Third switch S 3,k The first switch S is turned on. 1,k Fourth switch S 4,k When shut down, the first k Output of each basic submodule— U Bk ; If the cascaded H-bridge CHB has n Each basic submodule can output m Each level, n When it is even, m = n ; n When it is an odd number, m = ( n +1), in phase-shift carrier modulation, all triangular carriers have the same amplitude and frequency, and the phase difference between any two adjacent carriers is 360° / n .

3. A modular, reusable solar collector for wireless charging of electric vehicles according to claim 1, characterized in that, In photovoltaic power generation mode, the first... k Each basic submodule includes a synchronous rectification boost circuit, consisting of a first switching transistor S. 1,k Second switch S 2,k An inductor L k Voltage source U Bk Voltage source U PVk It consists of two capacitors; the first k Each basic submodule controls the first switching transistor S. 1,k Second switch S 2,k This is to enable MPPT to charge the battery pack.

4. A modular, reusable solar collector for wireless charging of electric vehicles according to claim 3, characterized in that, For the k -1 basic submodule and the first k The basic sub-modules perform equalization control in four stages: (1) Stage a: Inductor current i T lower limit I min Inductor current i T Inductor current i T upper limit I max U Bk-1 Through S 1,k-1 S 4,k-1 S 1,k and S 3,k Self-inductance of the transmitting coil L T Charging causes inductor current to flow. i T It increases linearly, while U Bk-1 Reduce; at this time, U Bk Self-inductance of the transmitting coil L T Continuation path; (2) Stage b: Inductor current i T ≥ Inductor current i T upper limit I max Inductor current i T The amplitude increases to its maximum value, causing S to... 4,k-1 Shutdown, S 3,k-1 Activation; U Bk-1 The discharge path is cut off, and the inductor current... i T Remain unchanged; (3) Stage c: Inductor current i T lower limit I min Inductor current i T Inductor current i T upper limit I max S 2,k-1 and S 2,k Activated under MPPT control, while S 1,k-1 and S 1,k Turn off; changes in the switching state of adjacent bridge arms cause S 4,k-1 Activation, S 3,k-1 Off; self-inductance of the transmitting coil L T Through S 2,k-1 S 4,k-1 S 2,k and S 3,k right U Bk Charging causes inductor current to flow. i T Linear decrease, U Bk Increase; (4) Stage d: Inductor current i T ≤Inductor current i T lower limit I min Inductor current i T The amplitude of S decreases to its minimum value, causing S to... 3,k Shutdown, S 4,k Activation; U Bk The charging path is interrupted, and the inductor current... i T The basics remain unchanged.

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