A vehicle wireless charging system of multiplexing OBC secondary circuit and a control method thereof

Abstract

The application discloses a kind of multiplexing OBC secondary circuit's vehicle wireless charging system and its control method, belong to wireless charging technical field.The system includes magnetic coupling receiving module, mode switching module, control module, OBC, vehicle controller, power battery, wherein, OBC includes OBC primary circuit and OBC secondary circuit;The mode switching module is connected between the output of the magnetic coupling receiving module and the wireless input of OBC secondary circuit;OBC secondary circuit output and the vehicle controller electric connection;The magnetic coupling receiving module, mode switching module, vehicle controller, OBC primary circuit, OBC secondary circuit are also respectively connected with the control module communication.The application realizes low cost, high integration of wireless charging.

Description

Technical Field

[0001] This invention belongs to the field of wireless charging technology. Specifically, this invention relates to a vehicle wireless charging system that reuses the OBC secondary circuit and its control method. Background Technology

[0002] The mainstream power battery platform for new energy unmanned logistics vehicles is currently a low-voltage platform (less than 96V), but high-voltage platforms (such as 350V) are becoming the future trend. Additionally, slow charging uses the traditional 6.6kW OBC, but this method requires manual operation, resulting in high labor costs. Currently, wireless charging solutions are mainly in the research stage, and their high cost poses a significant obstacle to engineering applications. Current wireless charging solutions typically require additional, complete receiver-side rectification, filtering, and compensation circuitry, leading to increased hardware costs and limited chassis mounting space. Furthermore, the rectifier bridge, filter capacitors, and resonant inductor on the OBC secondary side highly overlap in function with the subsequent processing circuitry of the wireless charging receiver.

[0003] Therefore, this invention proposes a vehicle wireless charging system and its control method that reuses the OBC secondary circuit. Summary of the Invention

[0004] This invention aims to overcome the shortcomings of the prior art and proposes a vehicle wireless charging system and its control method that reuses the OBC secondary circuit, in order to achieve the following objectives: to realize low-cost, highly integrated wireless charging.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a vehicle wireless charging system that reuses the secondary circuit of an OBC (On-Board Charger). The system includes a magnetic coupling receiver module, a mode switching module, a control module, an OBC, a vehicle controller, and a power battery. The OBC includes a primary circuit and a secondary circuit. The mode switching module is connected in series between the output of the magnetic coupling receiver module and the wireless input of the OBC secondary circuit. The output of the OBC secondary circuit is electrically connected to the power battery. The magnetic coupling receiver module, the mode switching module, the vehicle controller, the OBC primary circuit, and the OBC secondary circuit are also communicatively connected to the control module.

[0006] Furthermore, the magnetically coupled receiving module includes a receiving coil L, a first capacitor C1, a second capacitor C2, an inductor Ls, a capacitor Cs, and an output connector J1. The first end of the receiving coil L is connected to the first end of the first capacitor C1, the first end of the second capacitor C2, and the first end of the output connector J1. The second end of the receiving coil L is connected to ground, the second end of the first capacitor C1, the second end of the inductor Ls, the second end of the capacitor Cs, and the second end of the output connector J1. The second end of the second capacitor C2 is connected to the first end of the inductor Ls, the first end of the capacitor Cs, and the first end of the output connector J1. A voltage sensor is also connected in parallel across the two ends of the receiving coil L, and the voltage sensor is communicatively connected to the control module.

[0007] Furthermore, the mode switching module includes a relay K1, the control terminal of which is connected to the control module; the first end of the contact of the relay K1 is connected to the wireless input terminal of the OBC secondary circuit, and the second end is connected to the output terminal of the magnetic coupling receiving module; wherein, the control terminal of the relay K1 controls the opening and closing of the contact according to the control signal of the control module, thereby controlling the opening and closing of the path between the output terminal of the magnetic coupling receiving module and the wireless input terminal of the OBC secondary circuit.

[0008] Furthermore, a bleeder resistor R3 is connected in parallel across the contacts of the relay K1.

[0009] Furthermore, the mode switching module also includes a status detection circuit. In the status detection circuit, the first end of the contact of the relay K1 is connected to the negative input terminal of the optocoupler U1. The negative input terminal of the optocoupler U1 is also led out to a terminal and connected in series with a resistor R2 before being grounded. The positive input terminal of the optocoupler U1 is grounded. The output terminal of the optocoupler U1 is connected to the control module as a status detection output terminal. At the same time, the output terminal of the optocoupler U1 is connected in series with a pull-up resistor R4 and then connected to the power supply VCC. In addition, the output terminal of the optocoupler U1 is connected in series with a resistor R5 and then grounded.

[0010] Furthermore, the state detection circuit also includes an RC filter circuit, which includes a resistor R1 and a capacitor C1. The first contact of the relay K1 is connected to the first terminal of the resistor R1; the second terminal of the resistor R1 is connected to the negative input terminal of the optocoupler U1; and a terminal capacitor C1 is connected in series between the second terminal of the resistor R1 and the negative input terminal of the optocoupler U1 and then grounded.

[0011] Furthermore, the magnetic coupling receiving module, the mode switching module, and the vehicle controller are also connected to the control module via a CAN bus.

[0012] This invention also provides a control method for a vehicle wireless charging system that reuses the OBC secondary circuit. Using the aforementioned vehicle wireless charging system that reuses the OBC secondary circuit, the method includes: Step S1: System power-on initialization; Step S2: The vehicle controller detects whether the charging gun is inserted and sends the information to the control module. If it is not inserted, proceed to the next step. Step S3: The magnetic coupling receiving module detects the receiving coil voltage and sends it to the control module. The control module determines whether the receiving coil voltage is greater than a preset voltage threshold; if it is, proceed to the next step. Step S4: The control module controls the mode switching unit to switch to wireless charging mode. Correspondingly, the mode switching unit opens the path between the output terminal of the magnetic coupling receiver module and the wireless input terminal of the OBC secondary circuit. Step S5: The magnetic coupling receiving module obtains high-frequency AC power through the receiving coil and sends it to the OBC secondary circuit. After rectification and voltage regulation by the OBC secondary circuit, the power battery is charged.

[0013] Furthermore, in step S2, if the insertion of the charging gun is detected, the control module controls the mode switching unit to switch to wired charging mode. Correspondingly, the mode switching unit closes the path between the output terminal of the magnetic coupling receiver module and the wireless input terminal of the OBC secondary circuit. At this time, the electrical energy input by the charging gun is processed by the OBC primary circuit and the OBC secondary circuit in sequence and then sent to the power battery for charging.

[0014] Furthermore, throughout the charging process, the mode switching unit provides real-time feedback on the path status between the output of the magnetic coupling receiver module and the wireless input of the OBC secondary circuit to the control module via the status detection circuit. If the path status fed back by the control module after issuing the control signal from the mode switching unit does not match the target status of the control signal, an alarm will be triggered.

[0015] The technical effects of this invention are as follows: This invention achieves efficient reuse of the OBC secondary circuit, realizing a low-cost, highly integrated wireless charging solution. Traditional solutions require separate rectifiers, DC-DC converters, and controllers, resulting in high costs. This invention, by reusing the OBC secondary circuit, eliminates the need for a separate wireless charging rectifier unit, reducing system costs, the number and size of components, and facilitating vehicle layout and weight reduction.

[0016] The mode switching module of this invention achieves physical isolation between the coupling receiver module and the OBC secondary circuit through a mechanical relay, enabling seamless switching between wired and wireless charging modes. Attached Figure Description

[0017] Figure 1A schematic diagram of a vehicle wireless charging system architecture that reuses the OBC secondary circuit is provided in an embodiment of the present invention; Figure 2 A circuit diagram of a magnetic coupling receiving module provided in an embodiment of the present invention; Figure 3 A circuit diagram of a mode switching module provided in an embodiment of the present invention; Figure 4 The primary and secondary circuit diagrams of the OBC provided in the embodiments of the present invention are shown. Detailed Implementation

[0018] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. This is to help those skilled in the art to have a more complete, accurate, and in-depth understanding of the inventive concept and technical solutions of the present invention, and to facilitate its implementation. It should be noted that the terms "first," "second," etc., used in this application are only for the convenience of describing the technical solutions and to distinguish components; the corresponding component configurations may be the same or different, and are not intended to limit the scope of this application. To make the technical solutions of the present invention clearer, the present invention will be explained and illustrated through the following embodiments.

[0019] This invention provides a vehicle wireless charging system that reuses the OBC secondary circuit, aiming to solve the technical problems of ineffective reuse of the OBC secondary circuit, high system cost, and complex structure in existing electric vehicle wireless charging systems. The system achieves seamless switching between wired and wireless charging modes through a clever mode-switching module design, enabling efficient reuse of the OBC secondary circuit in both charging modes. This significantly reduces system cost and simplifies the overall vehicle electrical architecture.

[0020] like Figure 1 As shown, the system of this embodiment includes a magnetic coupling receiver module, a mode switching module, a control module, an OBC (On-Board Cell), a vehicle controller, and a power battery. The OBC includes a primary circuit and a secondary circuit. The mode switching module is connected in series between the output of the magnetic coupling receiver module and the wireless input of the secondary circuit. The output of the secondary circuit is electrically connected to the power battery. The magnetic coupling receiver module, mode switching module, vehicle controller, primary circuit, and secondary circuit are also communicatively connected to the control module.

[0021] CAN is a widely used serial communication protocol in the automotive field, featuring high speed, high reliability, multi-master structure, and non-destructive arbitration.

[0022] The core innovation of this invention lies in the following: Based on the traditional OBC architecture, a mode switching module is connected in series between the output of the magnetic coupling receiver module and the wireless input of the OBC secondary circuit, enabling flexible connection between the wireless charging receiver and the OBC secondary circuit. When the vehicle is in wireless charging mode, the mode switching module opens the path between the magnetic coupling receiver module and the OBC secondary circuit, allowing the high-frequency AC power obtained from the ground transmitter to be directly fed into the OBC secondary circuit for rectification and voltage regulation. When the vehicle is in wired charging mode, the mode switching module disconnects the above path, and the AC power input from the charging gun is processed by the OBC primary circuit before being fed into the OBC secondary circuit to charge the power battery. This design makes the OBC secondary circuit a shared rectification and voltage regulation unit for both wired and wireless charging modes, avoiding the need for a separate rectifier circuit for wireless charging in traditional solutions, and greatly improving system integration and cost-effectiveness.

[0023] The entire system operates as follows: After power-on initialization, the vehicle controller first checks if the charging gun is inserted. If the charging gun is inserted, the system enters wired charging mode. The mode switching module disconnects the path between the magnetic coupling receiver module and the OBC secondary circuit. The AC power input from the charging gun is processed sequentially through the OBC primary circuit and the OBC secondary circuit to charge the power battery. If the charging gun is not inserted, the magnetic coupling receiver module detects the receiving coil voltage. When the receiving coil voltage is greater than a preset threshold, it indicates that the vehicle is parked within an effective wireless charging area and the ground transmitter is functioning normally. At this time, the control module controls the mode switching module to switch to wireless charging mode, opening the path between the magnetic coupling receiver module and the OBC secondary circuit. The high-frequency AC power acquired by the magnetic coupling receiver module is directly fed into the OBC secondary circuit for rectification and voltage regulation, ultimately charging the power battery. Throughout the charging process, the status detection circuit built into the mode switching module provides real-time feedback on the path status to the control module, ensuring the accuracy and safety of mode switching.

[0024] The following section provides a detailed explanation of each module of the system.

[0025] The magnetic coupling receiver module is the energy receiving front-end of the wireless charging system in this embodiment. Its core function is to acquire high-frequency AC power from the ground-based wireless charging transmitter through electromagnetic induction, and then output the acquired power to the subsequent mode switching module and OBC secondary circuit after preliminary resonant tuning and impedance matching. The design of this module directly affects the transmission efficiency, power level, and operational stability of the wireless charging system.

[0026] like Figure 2As shown, the magnetic coupling receiving module in this embodiment adopts an LCC compensated topology, specifically including a receiving coil L, a first capacitor C1, a second capacitor C2, an inductor Ls, a capacitor Cs, and an output connector J1. The first end of the receiving coil L is connected to the first end of the first capacitor C1, the first end of the second capacitor C2, and the first end of the output connector J1. The second end of the receiving coil L is connected to ground, the second end of the first capacitor C1, the second end of the inductor Ls, the second end of the capacitor Cs, and the second end of the output connector J1. The second end of the second capacitor C2 is connected to the first end of the inductor Ls, the first end of the capacitor Cs, and the first end of the output connector J1. A voltage sensor is also connected in parallel across the two ends of the receiving coil L, and the voltage sensor is communicatively connected to the control module.

[0027] The receiving coil L is the core energy conversion element of the entire magnetic coupling receiving module. It is wound with multi-strand enameled copper wire, has 18 turns, and an inductance of 75μH. The first capacitor C1 and the second capacitor C2 are both 150nF metallized polypropylene film capacitors. The inductor Ls is a 40μH high-frequency inductor. The capacitor Cs is a 120nF capacitor. The output connector J1 is the physical connection interface between the magnetic coupling receiving module and the subsequent mode switching module. It can be AC-RF type, with a rated operating frequency of 85kHz, and is specifically designed for the transmission of high-frequency, high-power AC power. In this embodiment, all the above components are encapsulated as an IP67-rated module, achieving modular plug-and-play functionality.

[0028] The first capacitor C1 is connected in parallel across the receiving coil L, forming a parallel resonant circuit together with the receiving coil L. The main functions of this parallel resonant circuit include: (1) Reactive power compensation: The receiving coil L, as an inductive element, absorbs reactive power in AC operation. The parallel capacitor C1 can provide capacitive reactive power, which compensates for the reactive power absorbed by the coil, thereby reducing the total reactive power absorbed from the power supply side and improving the power factor of the system; (2) Resonant Tuning: The resonant frequency of the parallel resonant circuit is designed to match the system operating frequency (85kHz). In the resonant state, the equivalent impedance of the parallel circuit reaches its maximum value, exhibiting high impedance characteristics, which is beneficial to improving the output voltage and power transmission capability of the receiver. (3) Filtering effect: Parallel resonant circuits present high impedance to signals near the resonant frequency and low impedance to signals far from the resonant frequency. Therefore, they have a certain frequency selectivity and can filter out some high-frequency harmonic components, thus improving the output power quality.

[0029] The second capacitor C2, together with the inductor Ls and capacitor Cs, forms a series resonant branch, which, together with the parallel resonant circuit (L and C1), forms an LCC composite compensation structure. This composite structure combines the advantages of parallel compensation and series compensation, and can maintain high transmission efficiency over a wide load range.

[0030] Based on the LCC topology described above, the magnetically coupled receiver module in this embodiment exhibits an output current that is essentially independent of the load impedance when the system is in a resonant state, displaying an approximately constant current output characteristic. This characteristic is highly suitable for battery charging applications, as lithium batteries undergo two stages during charging: constant current charging and constant voltage charging. The constant current output characteristic simplifies the design of subsequent charging control circuits.

[0031] In addition, this embodiment also includes a voltage sensor connected in parallel across the receiving coil L to collect the induced voltage amplitude across the receiving coil L in real time. This voltage amplitude directly reflects the coupling state between the vehicle and the ground transmitter: when the vehicle is accurately aligned with the transmitter and the transmitter is working normally, the receiving coil voltage increases until it reaches its maximum value; when the vehicle deviates from the transmitter or the transmitter is not working, the receiving coil voltage decreases significantly or even to zero. Based on this, the control module can determine whether the vehicle is within a valid wireless charging area based on the receiving coil voltage value fed back by the voltage sensor. Specifically, the control module has a preset voltage threshold (set to 50V in this embodiment, but can be flexibly replaced according to actual conditions). When the receiving coil voltage is greater than this threshold, it is determined that the vehicle is parked in a valid wireless charging position and wireless charging can proceed; when the receiving coil voltage is less than this threshold, it is determined that the vehicle is not in a valid charging area and wireless charging will not be performed. The voltage sensor can also be used for system fault diagnosis. For example, if the receiving coil voltage is abnormally high, it may indicate that the resonant network is detuned or the load is open; if the voltage is abnormally low, it may indicate that the coil is short-circuited or the coupling is severely poor. The control module can perform fault diagnosis and alarm based on the abnormal voltage characteristics.

[0032] Voltage sensors are typically implemented using high-precision resistive voltage dividers or isolated voltage transformers. Their output signals are converted from analog to digital and then sent to the control module via the CAN bus.

[0033] The mode switching module reliably switches between wired and wireless charging modes, ensuring that the two modes operate mutually exclusively to avoid electrical conflicts and safety risks. This module is connected in series between the output of the magnetically coupled receiver module and the wireless input of the OBC secondary circuit, and its on / off state is switched via control signals from the control module.

[0034] Specifically, such as Figure 3As shown, the core actuator of the mode switching module is relay K1. The control terminal of relay K1 (i.e., the relay coil, which generates an electromagnetic field to drive the contact mechanism when energized) is connected to the control module. The first end of the contact of relay K1 is connected to the wireless input terminal of the OBC secondary circuit, and the second end is connected to the output terminal of the magnetic coupling receiver module. The control terminal of relay K1 controls the opening and closing of the contacts according to the control signal from the control module, thereby controlling the connection between the output terminal of the magnetic coupling receiver module and the wireless input terminal of the OBC secondary circuit. In this embodiment, relay K1 is selected as a high-voltage relay with a withstand voltage of 750V and a rated current of 30A.

[0035] In addition, this embodiment also connects a bleeder resistor R3 in parallel across the contacts of the relay K1. In wireless charging mode, when the relay K1 switches from the closed state to the open state, residual charge may be stored in the resonant network of the magnetic coupling receiver module. Since the capacitors (C1, C2, Cs) in the resonant network store electric field energy during charging, if the relay is suddenly disconnected, these residual charges have nowhere to be released, potentially causing a high voltage to remain across the resonant network. This residual voltage not only poses a safety hazard (risk of electric shock for maintenance personnel) but may also generate a large inrush current when the relay recloses. The bleeder resistor R3 provides a release path for the residual charge. When the relay is disconnected, the capacitors in the resonant network slowly discharge through R3, and the voltage gradually decreases to a safe level.

[0036] In this embodiment, the resistance value of the bleeder resistor R3 is selected as 150kΩ, but it can be flexibly selected according to the actual situation in specific implementation. If the resistance value is too small, although the bleedering speed is fast, R3 will divert some current when the relay is closed for wireless charging, resulting in power consumption and efficiency loss; if the resistance value is too large, the bleedering speed will be slowed down, and the safety protection effect will be reduced.

[0037] The mode switching module in this embodiment also includes a status detection circuit, which is used to detect the on / off state of the relay K1 contact in real time and feed the detection result back to the control module. The status detection circuit is an important safety function module in this embodiment, ensuring the reliability and safety of mode switching.

[0038] The core component of the status detection circuit is the optocoupler U1, specifically model 6N137. In this status detection circuit, the first terminal of the contact of the relay K1 is connected to the negative input terminal of the optocoupler U1 (usually the cathode of the LED). The negative input terminal of the optocoupler U1 also has a terminal led out and connected in series with a resistor R2 to ground. The positive input terminal of the optocoupler U1 (usually the anode of the LED) is grounded. The output terminal of the optocoupler U1 (usually the collector of the transistor) is connected to the control module as the status detection output terminal. At the same time, the output terminal of the optocoupler U1 is connected in series with a pull-up resistor R4 and then connected to the power supply VCC. Furthermore, the output terminal of the optocoupler U1 is connected in series with a resistor R5 and then grounded.

[0039] The working principle of the state detection circuit is as follows: When relay K1 contacts open, the output terminal of the magnetic coupling receiver module (the second end of the contact) is open-circuited with the wireless input terminal of the OBC secondary circuit (the first end of the contact). At this time, because relay K1 contacts are open, the voltage at the first end of the contact is close to ground potential; if relay K1 contacts are closed, the first end of the contact will present a certain high-frequency AC voltage. Therefore, when relay K1 contacts open, the LED inside optocoupler U1 is in the off state, and correspondingly, the transistor inside optocoupler U1 is cut off, and the output terminal of optocoupler U1 outputs a high level due to the pull-up resistor R4; when relay K1 contacts close, the LED inside optocoupler U1 is energized and conducts, emitting light. Correspondingly, this light source is received by the photodetector inside optocoupler U1 and drives the transistor to conduct. At this time, the output terminal of optocoupler U1 is pulled low and outputs a low level.

[0040] In this embodiment, optocoupler U1 achieves electrical isolation between the high-voltage area (high-voltage side, the area at the same potential as the relay contacts) and the low-voltage area (low-voltage side, the area where the control module is located). This isolation is crucial because the relay contacts may carry high voltages of hundreds of volts, while the control module typically operates at low voltage logic levels of 5V or 3.3V. Direct connection would pose safety risks and damage to the equipment.

[0041] Additionally, regarding resistor R2, it is connected in series between the negative input terminal of optocoupler U1 and ground. Its main function is to limit the current flowing through the internal LED of optocoupler U1, preventing excessive current from damaging the optocoupler. The resistance value of R2 can be selected as 1kΩ. Resistor R4 is connected in series between the positive power supply terminal of optocoupler U1 and VCC, serving as a pull-up resistor for the optocoupler output. Since the output terminal of 6N137 has an open collector structure, an external pull-up resistor is required to output a high level. In this embodiment, the resistance value of R4 can be selected as 2.2kΩ. Resistor R5 is connected in series between the output terminal of optocoupler U1 and ground, forming a voltage divider relationship with R4. It is used to adjust the amplitude of the output level to output a stable MCU_EN status signal to the vehicle controller, realizing fault diagnosis of relay engagement, disengagement, and sticking. The resistance value of R4 can be selected as 10kΩ. In this embodiment, the state detection circuit further includes an RC filter circuit, which includes a resistor R1 and a capacitor C1. The first terminal of the relay K1 contact is connected to the first terminal of the resistor R1; the second terminal of the resistor R1 is connected to the negative input terminal of the optocoupler U1; a terminal is led out between the second terminal of the resistor R1 and the negative input terminal of the optocoupler U1, connected in series with a capacitor C1, and then grounded. That is, R1 and C1 form a low-pass filter connected between the first terminal of the relay contact and the input terminal of the optocoupler. In this embodiment, the resistor R1 = 10Ω and C1 = 1μF.

[0042] The main function of an RC filter circuit is to filter out high-frequency noise and interference, preventing optocoupler malfunction. During high-frequency, high-current switching, relay contacts may generate arcing and electromagnetic interference, which can enter the status detection circuit through parasitic coupling. An RC low-pass filter can effectively filter out this high-frequency noise. When the relay contacts open, voltage spikes may occur (due to the release of energy stored in the line inductance and resonant network). The RC filter circuit can absorb and mitigate these voltage spikes, protecting the optocoupler from overvoltage damage. Furthermore, for 85kHz high-frequency AC signals, the RC filter circuit can smooth them into an approximately DC voltage signal, allowing the optocoupler to more stably reflect the state of the relay contacts.

[0043] For example Figure 3 As shown, the status detection circuit is divided into two parts by dashed lines: a high-voltage area and a low-voltage area. The high-voltage area includes relay K1, bleeder resistor R3, and RC filter circuit (R1, C1). The low-voltage area includes resistor R2, the input side of optocoupler U1, the output side of optocoupler U1, resistors R4 and R5, and the status detection output terminal MCU_EN. This partitioned design is based on safety considerations: the high-voltage area may carry high voltages of hundreds of volts, requiring high insulation and withstand voltage; the low-voltage area is the control circuit, with low voltage, requiring strict safety requirements for personnel and equipment. Optocoupler U1, as an isolation element spanning the two areas, has sufficient insulation distance and withstand voltage rating between its input and output to ensure that high voltage from the high-voltage area does not enter the low-voltage area.

[0044] The control module is the central control unit of the wireless charging system in this embodiment. It is responsible for coordinating the work of each module, realizing intelligent judgment and switching control of charging modes, as well as real-time monitoring and safety protection of the charging process. The control module communicates with the magnetic coupling receiving module, the mode switching module, and the vehicle controller via the CAN bus to obtain the status information and parameter data of each module, and issues corresponding control commands according to the preset control algorithm.

[0045] In this embodiment, the control module uses a microcontroller (MCU, such as the STM32G4 series) as its core processor, responsible for running control algorithms, processing communication protocols, and managing peripheral interfaces. The MCU offers strong real-time performance, meeting real-time control requirements; it also features rich peripheral interfaces and high expandability. Simultaneously, the control module is equipped with a CAN communication interface to establish communication with the magnetic coupling receiver module, mode switching module, and vehicle controller via the CAN bus.

[0046] On-board charger (OBC) is one of the core power electronic devices in electric vehicles. Its function is to convert external AC power (from the power grid or wireless charging receiver) into DC power suitable for charging the battery. Figure 4 As shown, the OBC in this embodiment adopts a traditional two-stage structure, including a primary circuit and a secondary circuit. The output of the primary circuit is connected to the input of the secondary circuit. Simultaneously, the input of the secondary circuit needs to be designed to accept high-frequency AC power from two sources: Wired charging mode: High-frequency AC power output from the high-frequency inverter in the primary circuit, the frequency of which is usually set internally by the OBC.

[0047] Wireless charging mode: High-frequency AC power output from the magnetic coupling receiver module, typically 85kHz (compliant with wireless charging standards).

[0048] Both the OBC primary circuit and the OBC secondary circuit are configured to connect to the control module, so that the control module can output control signals to the OBC primary circuit and / or the OBC secondary circuit to drive their operation according to the actual situation of wireless charging mode and wired charging mode.

[0049] The OBC primary circuit includes a PFC (Power Factor Correction) circuit, an LLC full-bridge inverter circuit (containing four NMOS transistors Q1 to Q4), a resonant capacitor Cres, and a resonant inductor Lres. The OBC secondary circuit includes a rectifier circuit consisting of full-bridge rectifier transistors D1 to D4 and filter capacitors C1 and C2. In operation, the control module controls the switching frequency of Q1 to Q4 or D1 to D4 through the output control signal, thereby controlling the OBC primary and secondary circuits.

[0050] The OBC secondary circuit is a key reuse object in this embodiment. Its function is to rectify, filter, and regulate the input high-frequency AC power (from the inverter in the primary circuit or from the wireless charging receiver) and then output it to the power battery. Wireless access points a and b are set on the OBC secondary circuit as wireless access terminals, which are connected to the output of the mode switching module.

[0051] In this embodiment, the Vehicle Control Unit (VCU) is the central control unit of the electric vehicle, responsible for coordinated control at the vehicle level. In the wireless charging system of this invention, the VCU is primarily used for charging gun insertion detection. The VCU determines whether the charging gun is inserted into the vehicle by detecting the physical connection status of the charging gun connector (such as CC signal, CP signal, etc.). The CC signal detects the connection status through resistance, while the CP signal achieves more complex interaction through PWM communication. When the charging gun is inserted, the VCU sends the charging gun insertion status to the control module via the CAN bus. This is the key basis for the system to determine whether to enter wired charging mode.

[0052] The power battery is the target charging object of the system in this embodiment. In this embodiment, a Battery Management System (BMS) is configured for the power battery. The BMS is used to detect the charging status during charging and to detect problems such as overcharging, overcurrent, and overtemperature. The BMS is configured to connect to the control module via a CAN bus. Based on this, when problems such as overcharging, overcurrent, or overtemperature occur, the control module can control relay K1 to disconnect to stop wireless charging, and simultaneously control the OBC to stop working to stop wired charging, thus realizing fault protection for the charging process.

[0053] This embodiment also proposes a control method for a vehicle wireless charging system that reuses the OBC secondary circuit. Using the above-mentioned vehicle wireless charging system that reuses the OBC secondary circuit, the method includes: Step S1: System power-on initialization; Step S2: The vehicle controller detects whether the charging gun is inserted and sends the information to the control module. If it is not inserted, proceed to the next step. Step S3: The magnetic coupling receiving module detects the receiving coil voltage and sends it to the control module. The control module determines whether the receiving coil voltage is greater than a preset voltage threshold; if it is, proceed to the next step. Step S4: The control module controls the mode switching unit to switch to wireless charging mode. Correspondingly, the mode switching unit opens the path between the output terminal of the magnetic coupling receiver module and the wireless input terminal of the OBC secondary circuit. Step S5: The magnetic coupling receiving module obtains high-frequency AC power through the receiving coil and sends it to the OBC secondary circuit. After rectification and voltage regulation by the OBC secondary circuit, the power battery is charged.

[0054] Referring to step S1, system power-on initialization is the starting point of the entire control process, which specifically includes: hardware initialization, including the MCU of the control module, the vehicle controller, the OBC main controller, etc.; communication initialization, including the initialization of the CAN bus status; parameter configuration, including the setting of various thresholds in the control algorithm.

[0055] Referring to step S2, the control module receives the charging gun status message sent by the vehicle controller via the CAN bus. This message typically contains the following information: charging gun connection status (inserted or not inserted); charging gun type (AC slow charging or DC fast charging); CC signal status (connection confirmation resistor value); CP signal status (control guide PWM duty cycle).

[0056] If the charging gun is detected to be inserted, the control module switches the mode switching unit to wired charging mode. Correspondingly, the mode switching unit closes the path between the output of the magnetic coupling receiver module and the wireless input of the OBC secondary circuit. At this time, the electrical energy input from the charging gun is processed sequentially through the OBC primary circuit and the OBC secondary circuit before being sent to the power battery for charging. Specifically: the control module sends a disconnect command to the mode switching module to ensure that relay K1 is in the open state; subsequently, the control module sends a wired charging mode command to the OBC, and the OBC immediately enters the wired charging process, with charging completed jointly by the OBC primary and secondary circuits. Normally, even if the vehicle is within the wireless charging area and the receiving coil has voltage, wireless charging will not be activated.

[0057] If the charging gun is not detected to be inserted, the system enters the wireless charging detection process, see step S3. The control module receives the receiving coil voltage data sent by the magnetic coupling receiving module via the CAN bus. The voltage sensor monitors the induced voltage across the receiving coil L in real time and periodically sends this data to the control module. The control module compares the receiving coil voltage with a preset voltage threshold: If the voltage of the receiving coil is greater than the preset voltage threshold, it is determined that the vehicle is in an effective wireless charging area and the ground transmitter is working normally, so wireless charging can be performed, and proceed to step S4. If the voltage of the receiving coil is less than or equal to the preset voltage threshold, it is determined that the vehicle is not in an effective wireless charging area or the ground transmitter is not working. In this case, return to step S2 to continue the detection.

[0058] To avoid misjudgments caused by transient interference, voltage judgment usually requires filtering: Time filtering: Requires the voltage to exceed the threshold for a certain period of time (e.g., 1-3 seconds) before it is considered valid; Multiple sampling: Validity is determined only if multiple consecutive sampled values ​​exceed the threshold; Hysteresis comparison: Changes the preset voltage threshold to a threshold range defined by two thresholds, exceeding the upper threshold determines entry into the charging area, and falling below the lower threshold determines exit from the charging area, avoiding jitter near the threshold.

[0059] Referring to step S4, after confirming wireless charging, the control module's control mode switching unit switches to wireless charging mode. Specifically, the control module sends a closing command to relay K1, energizing the relay coil. After the relay coil is energized, the relay contact structure closes, creating a path between the magnetic coupling receiver module's output and the OBC secondary circuit's wireless input. Simultaneously, the control module sends a wireless charging mode command to the OBC to activate the OBC secondary circuit. By fine-tuning the switching frequency of each switch in the OBC secondary circuit, precise control of the output voltage and current is achieved to match the constant current / constant voltage charging curve of the 350V power battery.

[0060] Referring to step S5, after the above processing, the power battery officially begins wireless charging. The energy transmission path in wireless charging mode is: ground transmitter → magnetic coupling receiver module → closed relay K1 → OBC secondary circuit → power battery.

[0061] In addition, based on the status detection circuit set in this embodiment, during the entire charging process, the mode switching unit provides real-time feedback on the path status between the output of the magnetic coupling receiver module and the wireless input of the OBC secondary circuit to the control module. If the path status fed back after the control module sends a control signal from the mode switching unit does not match the target status of the control signal, an alarm is triggered. For example, in wireless charging mode, the control module issues a closing command for relay K1. However, after a period of time, the status detection circuit detects that MCU_EN has not changed to a low level, indicating that relay K1 is not closed. This can be determined as a relay closure fault, at which point the control module can issue an alarm to the user, including local audible and visual alarms and remote communication alarms.

[0062] In addition, the method in this embodiment also includes a fault handling process: regardless of whether it is in wireless charging mode or wired charging mode, the battery management system (BMS) detects abnormalities such as overcharging, overcurrent, and overtemperature of the power battery in real time and feeds them back to the control module. If there are no abnormalities such as overcharging, overcurrent, or overtemperature, the control module maintains the current charging. If the control module detects any of the abnormalities such as overcharging, overcurrent, or overtemperature, the control module immediately controls the relay K1 to disconnect to stop wireless charging, and at the same time controls the OBC to stop working to stop wired charging. Simultaneously, the control module sends an alarm signal to drive the alarm device to sound an alarm to remind the user.

[0063] In summary, this embodiment achieves efficient reuse of the OBC secondary circuit. Traditional solutions require independent rectifiers, DC-DC converters, and controllers, resulting in high costs. This embodiment, by reusing the OBC secondary circuit, eliminates the need for a separate wireless charging rectifier unit, reducing system costs, the number and size of components, and facilitating vehicle layout and weight reduction.

[0064] This embodiment incorporates a mode switching module that uses mechanical relays for physical isolation, ensuring that the two modes operate mutually exclusively. Simultaneously, the mode switching module introduces an optocoupler-isolated state detection circuit to monitor the relay status in real time, enabling closed-loop control and safety diagnostics. The optocoupler provides electrical isolation between the high-voltage and low-voltage areas, ensuring the safety of the control circuit.

[0065] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution; or the direct application of the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A vehicle wireless charging system that reuses the OBC secondary circuit, characterized in that: The system includes a magnetic coupling receiver module, a mode switching module, a control module, an OBC (On-Board Cell), a vehicle controller, and a power battery. The OBC includes a primary circuit and a secondary circuit. The mode switching module is connected in series between the output of the magnetic coupling receiver module and the wireless input of the OBC secondary circuit. The output of the OBC secondary circuit is electrically connected to the power battery. The magnetic coupling receiver module, the mode switching module, the vehicle controller, the OBC primary circuit, and the OBC secondary circuit are also communicatively connected to the control module.

2. The vehicle wireless charging system with multiplexed OBC secondary circuit according to claim 1, characterized in that: The magnetically coupled receiving module includes a receiving coil L, a first capacitor C1, a second capacitor C2, an inductor Ls, a capacitor Cs, and an output connector J1. The first end of the receiving coil L is connected to the first ends of the first capacitor C1, the second capacitor C2, and the output connector J1. The second end of the receiving coil L is connected to ground, the second end of the first capacitor C1, the second end of the inductor Ls, the second end of the capacitor Cs, and the second end of the output connector J1. The second end of the second capacitor C2 is connected to the first ends of the inductor Ls, the first end of the capacitor Cs, and the first end of the output connector J1. A voltage sensor is also connected in parallel across the two ends of the receiving coil L, and the voltage sensor is communicatively connected to the control module.

3. A vehicle wireless charging system that reuses the OBC secondary circuit according to claim 1, characterized in that: The mode switching module includes a relay K1, the control terminal of which is connected to the control module. The first end of the contact of the relay K1 is connected to the wireless input terminal of the OBC secondary circuit, and the second end is connected to the output terminal of the magnetic coupling receiving module. The control terminal of the relay K1 controls the opening and closing of the contact according to the control signal of the control module, thereby controlling the opening and closing of the path between the output terminal of the magnetic coupling receiving module and the wireless input terminal of the OBC secondary circuit.

4. A vehicle wireless charging system that reuses the OBC secondary circuit according to claim 3, characterized in that: A bleeder resistor R3 is connected in parallel across the contacts of the relay K1.

5. A vehicle wireless charging system for reusing the OBC secondary circuit according to any one of claims 3 or 4, characterized in that: The mode switching module also includes a status detection circuit. In the status detection circuit, the first end of the contact of the relay K1 is connected to the negative input terminal of the optocoupler U1. The negative input terminal of the optocoupler U1 is also connected to a terminal and grounded after being connected in series with a resistor R2. The positive input terminal of the optocoupler U1 is grounded. The output terminal of the optocoupler U1 is connected to the control module as a status detection output terminal. At the same time, the output terminal of the optocoupler U1 is connected to the power supply VCC after being connected in series with a pull-up resistor R4. Furthermore, the output terminal of the optocoupler U1 is connected to the ground after being connected in series with a resistor R5.

6. A vehicle wireless charging system that reuses the OBC secondary circuit according to claim 5, characterized in that: The state detection circuit also includes an RC filter circuit, which includes a resistor R1 and a capacitor C1. The first terminal of the contact of the relay K1 is connected to the first terminal of the resistor R1; the second terminal of the resistor R1 is connected to the negative input terminal of the optocoupler U1; and a terminal capacitor C1 is connected in series between the second terminal of the resistor R1 and the negative input terminal of the optocoupler U1 and then grounded.

7. A vehicle wireless charging system that reuses the OBC secondary circuit according to claim 1, characterized in that: The magnetic coupling receiving module, mode switching module, and vehicle controller are also connected to the control module via a CAN bus.

8. A control method for a vehicle wireless charging system that reuses the OBC secondary circuit, using a vehicle wireless charging system that reuses the OBC secondary circuit according to any one of claims 1-7, characterized in that: The method includes: Step S1: System power-on initialization; Step S2: The vehicle controller detects whether the charging gun is inserted and sends the information to the control module. If it is not inserted, proceed to the next step. Step S3: The magnetic coupling receiving module detects the receiving coil voltage and sends it to the control module. The control module determines whether the receiving coil voltage is greater than a preset voltage threshold; if it is, proceed to the next step. Step S4: The control module controls the mode switching unit to switch to wireless charging mode. Correspondingly, the mode switching unit opens the path between the output terminal of the magnetic coupling receiver module and the wireless input terminal of the OBC secondary circuit. Step S5: The magnetic coupling receiving module obtains high-frequency AC power through the receiving coil and sends it to the OBC secondary circuit. After rectification and voltage regulation by the OBC secondary circuit, the power battery is charged.

9. The control method for a vehicle wireless charging system that reuses the OBC secondary circuit according to claim 8, characterized in that: In step S2, if the insertion of the charging gun is detected, the control module controls the mode switching unit to switch to wired charging mode. Correspondingly, the mode switching unit closes the path between the output of the magnetic coupling receiver module and the wireless input of the OBC secondary circuit. At this time, the electrical energy input by the charging gun is processed by the OBC primary circuit and the OBC secondary circuit in sequence and then sent to the power battery for charging.

10. A control method for a vehicle wireless charging system that reuses the OBC secondary circuit according to claim 8 or 9, characterized in that: Throughout the charging process, the mode switching unit provides real-time feedback on the path status between the output of the magnetic coupling receiver module and the wireless input of the OBC secondary circuit to the control module via the status detection circuit. If the path status fed back by the control module after sending a control signal from the mode switching unit does not match the target status of the control signal, an alarm will be triggered.

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