Underwater wireless power transmission device

Abstract

The underwater wireless power transmission device based on impedance matching solves the problem that the mutual inductance value of the receiving and transmitting coils of the underwater wireless power transmission system changes due to relative position offset, thereby causing a decrease in power transmission efficiency. It belongs to the field of wireless power transmission of underwater robots. The present invention includes a DC-DC conversion circuit, a full-bridge inverter circuit, a coupling circuit, a full-bridge active rectifier circuit and a control device; the output of the DC power supply at the transmitting end passes through the DC-DC conversion circuit and the full-bridge inverter circuit in sequence, and then is input into the full-bridge active rectifier circuit through the coupling circuit; the control device is used to control the DC-DC conversion circuit, the full-bridge inverter circuit, the coupling circuit, and the full-bridge active rectifier circuit to realize underwater wireless power transmission, wherein the control device changes the equivalent impedance of the receiving end by changing the duty cycle of the MOSFET active rectifier device in the full-bridge active rectifier circuit, thereby realizing impedance adaptation and completing impedance matching.

Description

Technical Field

[0001] The invention relates to an underwater wireless power transmission device, belonging to the field of wireless power transmission of underwater robots. Background Art

[0002] The power supply of underwater robots (AUVs) is a crucial factor in determining their operational capabilities and range. Traditional floating charging methods lack visibility, are complex, and require long operation times, severely impacting the AUV's operating radius and lifespan. Wireless power transmission (WPT), a contactless energy transmission method, can significantly improve the AUV's stealth, safety, and reliability.

[0003] However, existing wireless power transmission devices have some problems in specific underwater environments. For example, the position of the underwater robot will continue to fluctuate randomly due to changes in the seabed ocean currents, and the resulting fluctuations in the mutual inductance of the coils will interfere with the system's transmission efficiency. Therefore, dynamic wireless power transmission efficiency is one of the important parameters for evaluating the overall performance of the system. There are few related inventions for this problem, and the current hot topic of invention is to improve transmission efficiency through impedance matching. There are three main research methods for impedance matching, including passive impedance matching networks, relay coil impedance matching, and active impedance matching networks. Passive impedance matching networks have disadvantages such as complex control methods, only discrete adjustment, and excessively large system size. The relay coil impedance matching method has high requirements on the relative positions of the coils at both ends, which greatly limits the flexibility of the equipment. The active impedance matching method is a two-stage control method at the receiving end, which is difficult to control. Summary of the Invention

[0004] To address the problem that the mutual inductance value of the receiving and transmitting coils of an underwater wireless power transmission system changes due to relative position offset, thereby causing a decrease in power transmission efficiency, the present invention provides an underwater wireless power transmission device.

[0005] An underwater wireless power transmission device of the present invention includes a DC-DC conversion circuit, a full-bridge inverter circuit, a coupling circuit, a full-bridge active rectification circuit and a control device;

[0006] The output of the DC power supply at the transmitting end passes through the DC-DC conversion circuit and the full-bridge inverter circuit in sequence, and then is input into the full-bridge active rectifier circuit through the coupling circuit;

[0007] The control device is used to control the DC-DC conversion circuit, full-bridge inverter power, coupling circuit, and full-bridge active rectification circuit to realize underwater wireless power transmission. The control device changes the duty cycle of the MOSFET active rectification device in the full-bridge active rectification circuit and thus changes the equivalent impedance of the receiving end, thereby realizing impedance adaptation and completing impedance matching.

[0008] Preferably, the control device changes the duty cycle of the MOSFET active rectifier device in the full-bridge active rectifier circuit by:

[0009] Get the optimal duty cycle D η-max :

[0010]

[0011] Where M is the mutual inductance, R is the internal resistance of the two-terminal coil, and R L is the real-time actual impedance value of the receiving end, and ω is the system operating angular frequency.

[0012] Preferably, the mutual inductance value is obtained by real-time identification, and the obtaining method is:

[0013]

[0014] Among them, D is the duty cycle value of the output of the set receiver, U in is the output voltage of the transmitter, I in is the output current value of the transmitter.

[0015] Preferably, the control device includes a transmitting end MCU controller, a PI controller, a No. 1 PWM generator and a No. 2 PWM generator, a receiving end MCU controller and a PWM drive circuit;

[0016] The transmitting end MCU controller and the receiving end MCU controller communicate wirelessly. The receiving end MCU controller transmits the actual load voltage value to the transmitting end MCU controller, and the transmitting end MCU controller transmits the RMS calculated value of the output voltage and current of the full-bridge inverter circuit to the receiving end MCU controller.

[0017] The PWM signal output terminal of PWM generator No. 1 is connected to the PWM signal input terminal of the DC-DC conversion circuit. The transmitting end MCU controller is connected to PWM generator No. 1 through a PI controller. The transmitting end MCU controller is used to control the duty cycle of the PWM signal transmitted to the DC-DC converter circuit according to the actual voltage value of the load, thereby controlling the system output voltage;

[0018] The PWM signal output terminal of the No. 2 PWM generator is connected to the PWM signal input terminal of the full-bridge inverter circuit. The transmitting end MCU controller controls the No. 2 PWM generator to output a high-frequency AC PWM signal to the full-bridge inverter circuit, thereby establishing a transmission magnetic field by the transmitting end MCU controller.

[0019] The MCU controller at the receiving end obtains the real-time actual impedance value R of the receiving end based on the RMS calculation value of voltage and current. L The receiving end MCU controller samples the receiving coil current synchronization signal in the coupling circuit, and then combines the obtained R L Calculate the optimal duty cycle Dη-max The receiving end MCU controller is based on the optimal duty cycle D η-max The full-bridge active rectifier circuit is driven by a PWM drive circuit.

[0020] Preferably, the DC-DC conversion circuit is a BUCK type step-down circuit.

[0021] Preferably, both the transmitting end MCU controller and the receiving end MCU controller are implemented using STM32F103VET6 model chips.

[0022] Preferably, the switching device in the full-bridge inverter circuit uses a DMT3009LDT-7 MOSFET tube as the switching device.

[0023] Preferably, the transmitting end MCU controller and the receiving end MCU controller use ESP8266 module for wireless communication.

[0024] Preferably, the switching device in the full-bridge active rectification circuit adopts a CMP060N10 NMOS switching tube.

[0025] The present invention has the beneficial effects of combining rectification and impedance matching functions in the rectifier circuit at the receiving end of wireless power transmission, thereby further reducing the overall circuit size and control difficulty. Furthermore, by collecting real-time parameters from the circuits at both ends and establishing a parameter identification model, the present invention achieves real-time identification of the mutual inductance value at both ends, thus enabling adaptive control of the optimal transmission efficiency of the underwater wireless power transmission system. Compared to other wireless power transmission devices based on impedance matching, the present invention has a smaller circuit size, significantly improving the portability of the equipment. Unlike other impedance matching methods that can only adjust the impedance matching control mode based on known mutual inductance values, the present invention can identify unknown mutual inductance values ​​by collecting real-time information from the two-end circuit devices. The present invention establishes a two-end wireless Wi-Fi communication mode based on actual underwater conditions, enabling rapid exchange of information parameters across the entire system. Compared to other wireless power transmission devices without impedance matching, the present invention can improve transmission efficiency by more than 5% when horizontal and vertical offsets are within 85%. The overall system response time is short, with good real-time performance, and the output voltage can be stably maintained at the previously set value. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a topological diagram of a wireless power transmission system based on active rectification and impedance matching;

[0027] Figure 2 This is the closed-loop control principle diagram of the wireless power transmission system based on active rectification impedance matching;

[0028] Figure 3This is the hardware circuit diagram of the DC-DC conversion circuit;

[0029] Figure 4 This is the hardware circuit diagram of the full-bridge inverter circuit;

[0030] Figure 5 This is the hardware circuit diagram of the full-bridge active rectifier circuit. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0032] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0034] To address the aforementioned issues, this embodiment proposes a wireless power transmission system based on active rectification and impedance matching. Based on this, a mutual inductance identification method is developed and a corresponding optimal efficiency tracking control strategy is designed. This achieves stable voltage output while maintaining a high transmission efficiency point for the overall underwater wireless power transmission system.

[0035] The underwater wireless power transmission device of this embodiment includes a DC-DC conversion circuit, a full-bridge inverter circuit, a coupling circuit, a full-bridge active rectification circuit and a control device;

[0036] The output of the DC power supply at the transmitting end passes through the DC-DC conversion circuit and the full-bridge inverter circuit in sequence, and then is input into the full-bridge active rectifier circuit through the coupling circuit;

[0037] The control device is used to control the DC-DC conversion circuit, full-bridge inverter power, coupling circuit, and full-bridge active rectification circuit to realize underwater wireless power transmission. The control device changes the duty cycle of the MOSFET active rectification device in the full-bridge active rectification circuit and thus changes the equivalent impedance of the receiving end, thereby realizing impedance adaptation and completing impedance matching.

[0038] This embodiment replaces the passive rectifier module in the existing impedance matching scheme with a synchronous active rectifier module. By varying the duty cycle of the MOSFET active rectifier device in the impedance matching circuit, the equivalent impedance of the receiving end's downstream stage is altered. Varying the active rectifier duty cycle causes changes in the system's equivalent impedance. A control device calculates the optimal impedance value and selects whether to increase or decrease the active rectifier duty cycle, thereby achieving impedance adaptation, completing impedance matching, and improving overall transmission efficiency.

[0039] In this embodiment, the control device changes the duty cycle of the MOSFET active rectifier device in the full-bridge active rectifier circuit by:

[0040] The optimal duty cycle calculation output model of the wireless power transmission device based on impedance matching is used to obtain the optimal duty cycle D η-max , the output model is:

[0041]

[0042] Where M is the mutual inductance, R is the internal resistance of the two-terminal coil, and R L is the real-time actual impedance value of the receiving end, and ω is the system operating angular frequency.

[0043] The mutual inductance value of this embodiment is obtained by real-time identification using a mutual inductance identification model of a wireless power transmission device based on impedance matching. The identification model is:

[0044]

[0045] Among them, D is the duty cycle value of the output of the set receiver, U in is the output voltage of the transmitter, I in is the output current value of the transmitter.

[0046] According to the experimental results, the initial value of D is set to 0.45.

[0047] In this embodiment, the real-time equivalent impedance value feedback control device of the subsequent circuit calculates the mutual inductance value at both ends of the coil in real time through the mutual inductance value identification model and stores it in the control device.

[0048] The control device of this embodiment includes a transmitting end MCU controller, a PI controller, a PWM generator No. 1 and a PWM generator No. 2, a receiving end MCU controller and a PWM drive circuit;

[0049] The transmitting end MCU controller and the receiving end MCU controller communicate wirelessly through the WIFI module. The receiving end MCU controller transmits the actual load voltage value to the transmitting end MCU controller, and the transmitting end MCU controller transmits the RMS calculated value of the output voltage and current of the full-bridge inverter circuit to the receiving end MCU controller;

[0050] The PWM signal output terminal of PWM generator No. 1 is connected to the PWM signal input terminal of the DC-DC conversion circuit. The transmitting end MCU controller is connected to PWM generator No. 1 through a PI controller. The transmitting end MCU controller is used to control the duty cycle of the PWM signal transmitted to the DC-DC converter circuit according to the actual voltage value of the load, thereby controlling the system output voltage;

[0051] The PWM signal output terminal of the No. 2 PWM generator is connected to the PWM signal input terminal of the full-bridge inverter circuit. The transmitting end MCU controller controls the No. 2 PWM generator to output a high-frequency AC PWM signal to the full-bridge inverter circuit, thereby establishing a transmission magnetic field by the transmitting end MCU controller.

[0052] The MCU controller at the receiving end obtains the real-time actual impedance value R of the receiving end based on the RMS calculation value of voltage and current. L The receiving end MCU controller samples the receiving coil current synchronization signal in the coupling circuit, and then combines the obtained R L Calculate the optimal duty cycle D η-max The receiving end MCU controller is based on the optimal duty cycle D η-max The full-bridge active rectifier circuit is driven by a PWM drive circuit.

[0053] The working process of this embodiment is as follows: the DC power supply transmits electrical energy to the Figure 3 The DC-DC conversion circuit shown. The DC-DC conversion circuit adopts a BUCK type step-down circuit. The transmitting end MCU controller compares the expected voltage with the actual output voltage of the receiving end through the PI controller, and controls the duty cycle of the PWM signal transmitted to the DC-DC conversion circuit, thereby controlling the system output voltage. Among them, the transmitting end MCU controller and the receiving end MCU controller both use the STM32F103VET6 model chip as the main control chip of the system. The maximum clock frequency allowed by this chip is 72MHZ. In order to increase the operation speed as much as possible, this embodiment designs an external clock of 8MHZ and sets the PLLXTPRE switch controller to non-frequency division mode. Then the transmitting end MCU controller controls the output of two high-frequency AC PWM signals and transmits them to the following Figure 4The full-bridge inverter circuit shown in the figure emits high-frequency alternating current to establish a transfer magnetic field. The switching device in the full-bridge inverter circuit uses a DMT3009LDT-7 MOSFET tube as a switching device. The device packages two MOSFET tubes together, which saves space. The RMS calculated value of the inverter circuit output voltage and current is then transmitted to the receiving end MCU controller through the WIFI module. The WIFI module uses the ESP8266 module. After the receiving end receives the high-frequency alternating current converted from the alternating magnetic field, the receiving end MCU controller samples the receiving coil current synchronization signal, and uses the optimal duty cycle calculation model combined with the received transmitter parameters to derive the optimal duty cycle for the emitted PWM signal, and sends the synchronized PWM signal to the receiving end. Figure 5 In the active rectification circuit shown, the switching devices in the full-bridge active rectification circuit use CMP060N10 NMOS switches to achieve rectification and impedance matching. The actual load voltage value is collected and transmitted to the transmitter MCU via the Wi-Fi module, completing the closed-loop voltage regulation task. This allows the entire system to achieve real-time optimal efficiency transmission and maintain a stable output voltage, ultimately achieving real-time tracking of the system's optimal efficiency.

[0054] This invention utilizes an active impedance matching device with active receiving-end rectification, enabling the receiving-end rectification circuit to combine rectification and impedance matching functions, further reducing the overall circuit size and control difficulty. Furthermore, by collecting real-time parameters from both ends of the circuit and establishing a parameter identification model, the invention achieves real-time identification of the mutual inductance between the two terminals, thus enabling adaptive control of the optimal transmission efficiency of the underwater wireless power transmission system.

[0055] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the invention. It should be understood that many modifications may be made to the illustrative embodiments, and that other arrangements may be devised, without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in ways other than those described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be employed in conjunction with other described embodiments.

Claims

1. An underwater wireless power transmission device, characterized in that: The device includes a DC-DC conversion circuit, a full-bridge inverter circuit, a coupling circuit, a full-bridge active rectification circuit and a control device; The output of the DC power supply at the transmitting end passes through the DC-DC conversion circuit and the full-bridge inverter circuit in sequence, and then is input into the full-bridge active rectifier circuit through the coupling circuit; The control device is used to control the DC-DC conversion circuit, full-bridge inverter power, coupling circuit, and full-bridge active rectification circuit to achieve underwater wireless power transmission. The control device changes the duty cycle of the MOSFET active rectification device in the full-bridge active rectification circuit to change the equivalent impedance of the receiving end, thereby achieving impedance adaptation and completing impedance matching. The control device changes the duty cycle of the MOSFET active rectifier device in the full-bridge active rectifier circuit by: Get the optimal duty cycle D η-max : Where M is the mutual inductance, R is the internal resistance of the two-terminal coil, and R L is the real-time actual impedance value of the receiving end, ω is the system operating angular frequency; The mutual inductance value is obtained by real-time identification, and the acquisition method is: Among them, D is the duty cycle value of the output of the set receiver, U in is the output voltage of the transmitter, I in is the output current value of the transmitter.

2. The underwater wireless power transmission device according to claim 1, characterized in that: The control device includes a transmitting end MCU controller, a PI controller, a No. 1 PWM generator and a No. 2 PWM generator, a receiving end MCU controller and a PWM drive circuit; The transmitting end MCU controller and the receiving end MCU controller communicate wirelessly. The receiving end MCU controller transmits the actual load voltage value to the transmitting end MCU controller, and the transmitting end MCU controller transmits the RMS calculated value of the output voltage and current of the full-bridge inverter circuit to the receiving end MCU controller. The PWM signal output terminal of PWM generator No. 1 is connected to the PWM signal input terminal of the DC-DC conversion circuit. The transmitting end MCU controller is connected to PWM generator No. 1 through a PI controller. The transmitting end MCU controller is used to control the duty cycle of the PWM signal transmitted to the DC-DC converter circuit according to the actual voltage value of the load, thereby controlling the system output voltage; The PWM signal output terminal of the No. 2 PWM generator is connected to the PWM signal input terminal of the full-bridge inverter circuit. The transmitting end MCU controller controls the No. 2 PWM generator to output a high-frequency AC PWM signal to the full-bridge inverter circuit, thereby establishing a transmission magnetic field by the transmitting end MCU controller. The MCU controller at the receiving end obtains the real-time actual impedance value R of the receiving end based on the RMS calculation value of voltage and current. L The receiving end MCU controller samples the receiving coil current synchronization signal in the coupling circuit, and then combines the obtained R L Calculate the optimal duty cycle D η-max The receiving end MCU controller is based on the optimal duty cycle D η-max The full-bridge active rectifier circuit is driven by a PWM drive circuit.

3. The underwater wireless power transmission device according to claim 2, characterized in that: The DC-DC conversion circuit is a BUCK type step-down circuit.

4. The underwater wireless power transmission device according to claim 2, characterized in that: The MCU controller of the transmitting end and the MCU controller of the receiving end are both implemented using the STM32F103VET6 model chip.

5. The underwater wireless power transmission device according to claim 2, characterized in that: The switching device in the full-bridge inverter circuit uses a DMT3009LDT-7 MOSFET tube as the switching device.

6. The underwater wireless power transmission device according to claim 2, characterized in that: The transmitting end MCU controller and the receiving end MCU controller use ESP8266 module for wireless communication.

7. The underwater wireless power transmission device according to claim 2, characterized in that: The switching device in the full-bridge active rectifier circuit adopts CMP060N10 NMOS switching tube.

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