CN105262154A - Wireless charging system for underwater robot and control method of wireless charging system - Google Patents

Abstract

The invention discloses a wireless charging system for an underwater robot and a control method thereof. The underwater wireless charging system includes a coupled transmitting end system and a receiving end system, and the transmitting end system includes a sequentially connected power supply system, an AC conversion system and a resonant circuit at the transmitting end; the receiving end system includes a receiving end resonant circuit, a receiving end DC conversion circuit and a receiving end load matching circuit; the energy control method includes a robot charging control and a charging power control algorithm, and the present invention utilizes electromagnetic induction The principle is to wirelessly charge the underwater robot. At the same time, an energy control method is designed to realize the control of the charging of the underwater robot, and realize the constant power charging under the condition of low charge and the control of full power failure.

Description

A wireless charging system for an underwater robot and its control method

technical field

The invention belongs to an underwater charging system and its control technology, in particular to an underwater robot wireless charging system and its control method.

Background technique

With the popularization of technology, the technology of underwater robots is more and more widely used in the civilian field, and the power supply method for underwater robots is relatively simple, mostly plug-in charging and battery replacement. Disadvantages: (1) Each plug-in charging requires the underwater robot to be charged from the bottom of the water, which greatly shortens the working time of the underwater robot underwater; (2) Frequent plug-in charging will make the interface aging , bringing potential safety hazards; (3) multiple battery replacements greatly reduce the life of the machine.

Contents of the invention

The purpose of the present invention is to provide a wireless charging system for an underwater robot and its control method, which can improve the safety of the circuit work and the transmission efficiency of energy, and at the same time manage the energy of the battery of the underwater robot to increase the underwater life of the underwater robot. During working hours, charging without an interface increases the safety of the underwater robot and increases the service life of the battery.

The technical solution to realize the object of the present invention is: a wireless charging system for an underwater robot, including a main circuit and a control circuit, the main circuit includes a coupling-connected transmitting end main circuit and a receiving end main circuit, and the transmitting end main circuit It includes a sequentially connected transmitting-end DC power supply system, a transmitting-end AC conversion system, and a transmitting-end resonant circuit, and the receiving-end main circuit includes a sequentially connected receiving-end resonant circuit, a receiving-end DC conversion circuit, and a receiving-end load matching transformation circuit;

The control circuit includes a transmitter control circuit and a receiver control circuit, the transmitter control circuit includes a transmitter PWM drive circuit and a transmitter current sampling circuit respectively connected to the transmitter digital signal processor DSP, the transmitter current sampling circuit Connected on the resonant circuit at the transmitting end; the receiving end control circuit includes a receiving end PWM drive circuit connected respectively on the receiving end digital signal processor DSP, two voltage sampling circuits at the receiving end and a receiving end current sampling circuit, the receiving end The first voltage sampling circuit at the receiving end of the two-way voltage sampling circuit at the receiving end is connected to the output end of the DC conversion circuit at the receiving end, and the second voltage sampling circuit at the receiving end is connected in series between the positive pole and the negative pole of the battery of the underwater robot. The sampling circuit is connected in series between the positive pole O of the battery of the underwater robot and the positive pole P of the load matching conversion circuit at the receiving end.

A control method for an underwater robot wireless charging system. First, detect the current of the resonant circuit at the transmitting end, and determine whether the receiving end is connected to the circuit through the current change of the resonant circuit at the transmitting end, that is, load detection. If the transmitting end detects that the receiving end is connected After entering the circuit, the digital signal processor DSP at the transmitting end issues a charging command, and the circuit enters a working state. The AC conversion system at the transmitting end is controlled by the PWM drive circuit at the transmitting end to output AC power, and the power is transmitted to the receiving end through the resonant circuit at the transmitting end. The receiving end passes through The resonant circuit at the receiving end receives the energy transmitted by the transmitting end, and converts the energy into AC output. After passing through the DC conversion circuit at the receiving end and the load matching circuit at the receiving end, it charges the battery of the underwater robot. If the transmitting end detects that the receiving end After leaving the circuit or the battery of the underwater robot at the receiving end is fully charged, the digital signal processor DSP at the transmitting end issues an instruction to stop charging, and will control the main circuit at the transmitting end to return to the detection mode;

Secondly, when the circuit is working, the current sampling circuit at the transmitting end samples the current of the resonant circuit at the transmitting end, usually samples the current of the resonant circuit at the transmitting end, compares the value of the sampling current with the zero value, and changes the The frequency of the PWM sent by the digital signal processor DSP at the transmitting end corrects the output frequency of the AC conversion system at the transmitting end to reach the resonant frequency of the resonant circuit at the transmitting end, that is, traces the resonant frequency;

Furthermore, when the main circuit at the receiving end is working, the second voltage sampling circuit at the receiving end samples the battery voltage of the underwater robot, and the current sampling circuit at the receiving end samples the charging current of the battery of the underwater robot, and the collected voltage and current information Send it to the digital signal processor DSP at the receiving end, and process it in the digital signal processor DSP at the receiving end, so that according to the processing result, a corresponding PWM signal is sent to control the charging mode of the underwater robot at the receiving end to realize the charging of the underwater robot. Battery energy management.

Compared with the prior art, the present invention has significant advantages: (1) An underwater wireless charging system is designed to realize contactless charging of underwater robots. (2) Using the principle of electromagnetic induction and load detection circuit, the detection of whether the receiving end is connected to the circuit is realized, and according to whether the receiving end is connected or not, it enters the continuous mode operation and the detection mode operation in a timely manner, avoiding excessive current, The safety performance of the circuit is improved. (3) By tracking the resonant frequency of the system, the output voltage frequency of the AC conversion system at the transmitting end is consistent with the resonant frequency of the resonant circuit at the transmitting end, which improves the energy transmission efficiency of the system. (4) The closed-loop control of the charging power of the underwater robot is realized through the battery energy control of the underwater robot, the constant power charging of the underwater robot is realized, and the charging state of the robot is detected in real time through the power.

The present invention will be described in further detail below in conjunction with the accompanying drawings.

Description of drawings

Fig. 1 is a main frame diagram of the underwater robot wireless charging system of the present invention (not including the underwater robot battery).

Fig. 2 is a schematic diagram of the main circuit of the present invention.

Fig. 3 is a schematic diagram of the control circuit of the transmitting end in the present invention.

Fig. 4 is a schematic diagram of the receiving end control circuit in the present invention.

Fig. 5 is a logic schematic diagram of the battery energy management control of the underwater robot in the present invention.

Fig. 6 is a flow chart of load detection in the present invention.

detailed description

1, the underwater robot wireless charging system of the present invention includes a main circuit and a control circuit, the main circuit includes a coupling-connected transmitter main circuit and a receiver main circuit, and the transmitter main circuit includes sequentially connected transmitters A DC power supply system, an AC conversion system at the transmitting end, and a resonant circuit at the transmitting end. The main circuit at the receiving end includes a resonant circuit at the receiving end, a DC conversion circuit at the receiving end, and a load matching conversion circuit at the receiving end connected in sequence.

The AC conversion system at the transmitting end converts the DC output of the DC power supply system at the transmitting end (inverting the voltage between electrode points A and B) into high-frequency alternating current, and converts the electric energy into field energy through the resonant circuit at the transmitting end, and then resonates at the receiving end The circuit receives the field energy sent by the transmitter, and converts the received field energy into AC power, which is converted into DC by the DC conversion circuit at the receiver, converted by the load matching conversion circuit at the receiver, and then output to charge the battery of the underwater robot. Wireless charging function.

The control circuit includes a transmitter control circuit and a receiver control circuit, the transmitter control circuit includes a transmitter PWM drive circuit and a transmitter current sampling circuit respectively connected to the transmitter digital signal processor DSP, the transmitter current sampling circuit Connected on the resonant circuit of the transmitting end; the receiving end control circuit comprises a receiving end PWM drive circuit connected respectively on the receiving end digital signal processor DSP, two voltage sampling circuits of the receiving end (by the first voltage sampling circuit of the receiving end, the first voltage sampling circuit of the receiving end, The second voltage sampling circuit at the receiving end is composed of) and the current sampling circuit at the receiving end, the first voltage sampling circuit at the receiving end of the two voltage sampling circuits at the receiving end is connected to the output end of the DC conversion circuit at the receiving end, and the second voltage sampling circuit at the receiving end The circuit is connected in series between the positive pole and the negative pole of the battery of the underwater robot, and the current sampling circuit at the receiving end is connected in series between the positive pole O of the battery of the underwater robot and the positive pole P of the load matching conversion circuit at the receiving end. The digital signal processing circuit can be composed of a dsPIC33FJ64GS606 chip and its peripheral power supply circuit.

2 and 3, the transmitter AC conversion system of the underwater robot wireless charging system of the present invention includes a first power MOS switch tube S1, a second power MOS switch tube S2, a third power MOS switch tube S3, and a fourth power MOS switch tube S3. Switch tube S4; the drain of the first power MOS switch tube S1 and the drain of the third power MOS switch tube S3 are connected to the positive pole A of the transmitting end DC power supply system, and the source of the first power MOS switch tube S1 is connected to the second power The drain of the MOS switch tube S2 is connected, the source of the third power MOS switch tube S3 is connected to the drain of the fourth power MOS switch tube S4, the source of the second power MOS switch tube S2, the fourth power MOS switch tube S4 The source of the transmitter is connected to the negative pole B of the DC power supply system at the transmitter, the gate of the first power MOS switch S1 is connected to the first PWM signal terminal of the PWM drive circuit at the transmitter, and the gate of the second power MOS switch S2 is connected to the transmitter The second PWM signal terminal of the terminal PWM drive circuit, the gate of the third power MOS switch S3 is connected to the third PWM signal terminal of the transmitter PWM drive circuit, and the gate of the fourth power MOS switch S4 is connected to the transmitter PWM The fourth PWM signal terminal of the drive circuit. The digital signal processor DSP at the transmitting end controls the action of the four power MOS switches at the transmitting end through the PWM driving circuit at the transmitting end, and the digital signal processor DSP at the receiving end controls a power MOS in the load matching circuit at the receiving end through the PWM driving circuit at the receiving end. Switch tube action.

2 and 3, the transmitter resonant circuit of the underwater robot wireless charging system of the present invention includes a transmitter resonant capacitor C1 and a transmitter resonant inductor L1, one end of the transmitter resonant capacitor C1 is connected to the first power MOS switch tube S1 The source is connected; the other end of the transmitter resonance capacitor C1 is connected to one terminal of the transmitter resonance inductor L1; the other end of the transmitter resonance inductor L1 is connected to the drain of the fourth power MOS switch S4.

Referring to Fig. 2 and Fig. 4, the receiving end DC conversion circuit of the underwater robot wireless charging system of the present invention includes a first diode VD1, a second diode VD2, a third diode VD3, and a fourth diode VD4; The cathode of the first diode VD1 and the cathode of the third diode VD3 are connected to one end of the third inductor L3, the anode of the first diode VD1 is connected to the cathode of the second diode VD2, and the third diode The anode of VD3 is connected to the cathode of the fourth diode VD4, the anode of the second diode VD2 is connected to the anode of the fourth diode VD4 and the source of the fifth power MOS switch S5. The DC conversion circuit at the receiving end rectifies the output voltage of the resonant circuit at the receiving end, and the terminals M and N are connected to the first voltage sampling circuit at the receiving end.

2 and 4, the receiving end resonant circuit of the underwater robot wireless charging system of the present invention includes a receiving end resonant capacitor C2 and a receiving end resonant inductance L2, and one end of the receiving end resonant capacitor C2 is connected to the anode of the first diode VD1 The other end is connected to one end of the resonant inductor L2 at the receiving end, and the other end of the resonant inductor L2 at the receiving end is connected to the cathode of the fourth diode VD4. The underwater robot receives the field energy transmitted by the resonant circuit at the transmitting end through the resonant inductor L2 and the resonant capacitor C2 at the receiving end and converts it into electrical energy, and charges the battery of the underwater robot after passing through the DC conversion circuit at the receiving end and the load matching circuit at the receiving end.

2 and 4, the receiving end load matching circuit of the underwater robot wireless charging system of the present invention includes a third inductor L3, a fifth power MOS switch S5, a fifth diode VD5 and a third capacitor C3. A third inductance C3 and a fifth diode VD5 are connected in series between the positive pole M output by the terminal DC conversion circuit and the positive pole P of the robot battery interface, and the drain of the fifth power MOS switch tube S5 is connected to the third inductance C3 and the fifth diode VD5. At the electrode point I between the diodes VD5, the source of the fifth power MOS switch is connected to the negative pole N output by the DC conversion circuit at the receiving end, and the gate of the fifth power MOS switch is connected to the first electrode of the PWM drive circuit at the receiving end. Five PWM signal terminals, a third capacitor C3 is connected in series between the positive pole P and the negative pole Q output by the load matching conversion circuit at the receiving end. The terminal PQ is connected to the second voltage sampling circuit at the receiving end. The voltage across the terminal PQ, the current at point R, and the voltage across the terminals M and N are used to realize the energy management of the robot battery, realize constant power charging and charging control, and match the load at the receiving end. The circuit converts the output voltage of the MN terminal of the DC conversion circuit at the receiving end, so that the output voltage level meets the voltage level of the robot battery, and at the same time satisfies the continuity of the input voltage and current, and outputs the voltage obtained by the third capacitor C3 to charge the robot battery; The PWM driving circuit at the receiving end receives the signal from the digital signal processor DSP at the transmitting end, and drives the first to fourth power MOS switches at the transmitting end to act; the PWM driving circuit at the receiving end receives the signal from the digital signal processor DSP at the receiving end signal to drive the fifth power MOS switch at the receiving end to act.

1 to 5, the present invention utilizes the above-mentioned control method of the wireless charging system for underwater robots, first of all, in the detection mode and the continuous operation mode, to detect the current of the resonant circuit at the transmitting end, and determine the current change of the resonant circuit at the transmitting end to determine the current of the receiving end. Whether it is connected to the circuit, that is, load detection, if the transmitter detects that the receiver is connected to the circuit, the digital signal processor DSP at the transmitter sends a charging command, the circuit enters a working state, and the output of the AC conversion system at the transmitter is controlled by the PWM drive circuit at the transmitter Alternating current, through the resonant circuit of the transmitting end, the electric energy is transmitted to the receiving end, and the receiving end receives the energy transmitted by the transmitting end through the resonant circuit of the receiving end, and converts these energy into AC output, and passes through the DC conversion circuit of the receiving end and the load matching circuit of the receiving end Finally, charge the battery of the underwater robot. If the transmitting end detects that the receiving end has left the circuit or the battery of the underwater robot at the receiving end is fully charged, the digital signal processor DSP at the transmitting end will issue a command to stop charging and will control the main circuit of the transmitting end. Circuit regression detection mode operation;

Secondly, when the circuit is working, the current sampling circuit at the transmitting end samples the current of the resonant circuit at the transmitting end, usually samples the current of the resonant circuit at the transmitting end, compares the value of the sampling current with the zero value, and changes the The frequency of the PWM sent by the digital signal processor DSP at the transmitting end corrects the output frequency of the AC conversion system at the transmitting end to reach the resonant frequency of the resonant circuit at the transmitting end, that is, traces the resonant frequency;

Furthermore, when the main circuit at the receiving end is working, the second voltage sampling circuit at the receiving end samples the battery voltage of the underwater robot, and the current sampling circuit at the receiving end samples the charging current of the battery of the underwater robot, and the collected voltage and current information Send it to the digital signal processor DSP at the receiving end, and process it in the digital signal processor DSP at the receiving end, so that according to the processing result, a corresponding PWM signal is sent to control the charging mode of the underwater robot at the receiving end to realize the charging of the underwater robot. Battery energy management.

In the control method of the underwater robot wireless charging system of the present invention, the specific method of load detection is: when the main circuit of the transmitting end starts to initialize, the main circuit of the transmitting end is in the detection mode and runs for 20 cycles every 1s. The middle point samples the current on the inductor (i.e. electrode point F) in the resonant circuit of the transmitting end, and takes the middle sampling value. If the current at this time is less than 20 amperes, the main circuit of the transmitting end will switch to continuous mode operation. If at this time If the current value is greater than 20 amperes, continue to run in the detection mode, take the middle sampling value, and compare it with the sampling value taken in the previous 1 second to determine the working mode of the circuit. When the receiving end is connected, the inductance coil at the receiving end will A mutual inductance impedance is generated at the transmitting end, so that the current in the inductance of the resonant circuit at the transmitting end produces a decrease in amplitude of about 2 amperes. If the current sampling value decreases by more than 2 amperes compared with the sampling value of the previous second, it proves that the main circuit of the receiving end is connected to the circuit, the circuit enters continuous mode operation, and the circuit continues to work to charge the battery of the underwater robot. During operation, the current on the transmitter inductor is sampled at the midpoint of the PWM every cycle, and the intermediate value is taken every second. At the same time, a comparison is made every second. If the detected current value increases by more than 2 amperes, then The transmitter stops working in the continuous mode and switches to the detection mode. If the current change is within 1 ampere compared with the sampling value of the previous second, it proves that the receiving end has no action, and the circuit maintains the previous mode operation.

During the working process of the circuit, in order to keep the circuit running at the maximum power and efficiency at all times, and save energy, the resonance point tracking will also be carried out. The phase difference between the current in the transmitter and the output voltage of the AC conversion system at the transmitter can be used to determine whether the transmitter circuit is working at the resonance point. In the control method of the underwater robot wireless charging system of the present invention, the method of resonant frequency tracking is: sampling the current on the inductor in the resonant circuit of the transmitting end at each rising edge of PWM, if the sampling value is greater than zero, it proves that the transmitting end The current in the resonant circuit is ahead of the output voltage of the AC conversion system at the transmitting end, and the circuit is capacitive, so increase the frequency of the output voltage of the AC conversion system at the transmitting end until the sampling value of the current is zero; if the sampling value is less than zero, it proves that The current in the resonant circuit at the transmitting end lags behind the output voltage of the AC conversion system at the transmitting end, and the circuit is inductive, so reduce the frequency of the output voltage of the AC conversion system at the transmitting end until the sampling value of the current is zero; if the sampling value is equal to zero, it proves that The current in the resonant circuit at the transmitting end is in the same phase as the output voltage of the AC conversion system at the transmitting end, and the circuit operates at the resonance point, so the frequency of the output voltage of the AC converting system at the transmitting end remains unchanged.

The control process of the present invention has also carried out energy management control to the battery, and the power matching closed-loop circuit in the system is actually equivalent to a simulated adjustable load, and since the output of the load matching circuit at the receiving end is an underwater robot battery, the voltage is fixed value, so this system controls the input voltage of the load matching circuit at the receiving end, the control object is the transfer function of the duty ratio to the input voltage, and the PI controller with zero-pole cancellation is selected to control the input voltage. First, Sampling the input voltage of the load matching circuit at the receiving end, that is, the voltage between point M and point N, comparing it with the set value, and performing PI calculation through the digital signal processor DSP at the receiving end to obtain a new PWM duty cycle. Output to the load matching circuit at the receiving end to control the input voltage of the load matching circuit at the receiving end. By controlling the input voltage of the load matching circuit at the receiving end, the value of the analog load is controlled, thereby controlling the transmission power, and at the same time matching the load at the receiving end The output voltage and output current of the circuit are sampled, and the real-time output power is calculated. By comparing with the given value, it is processed by the digital signal processor DSP at the receiving end to change the PWM duty cycle, thereby changing the output power of the system to achieve the given value. Constant value to achieve constant power charging. That is, in the control method of the underwater robot wireless charging system of the present invention, the battery energy management method of the underwater robot is as follows: when the battery power is lower than 50%, charging is performed; when the battery current is higher than 90%, the load matching converter End charging, that is, when charging the underwater robot, control the charging power of the battery to realize constant power charging, which is specifically realized by double-loop closed-loop control: sampling the voltage and charging current of the battery, and performing a test with a given constant power For comparison, the error is integrally processed by the digital signal processor DSP to generate a reference value for the input voltage of the power matching converter; the input voltage of the power matching converter is controlled to control the output power, that is, the charging power of the battery to a given constant power , to achieve constant power charging. As shown in Figure 5, it is the schematic diagram of battery energy management control, C _P is the power controller, LUT is the battery power monitoring controller, C _V is the voltage controller, G _V is the control duty obtained by using the small signal analysis method Ratio to the transfer function of the output voltage V _MN , H _V is the transfer function of the output voltage sampling circuit, this control system aims to detect and manage the battery power, and at the same time control the charging power of the battery to achieve constant power charging, the battery The power detection controller LUT is a look-up table instruction, the power controller _Cp is a power calculation instruction, the _voltage controller CV, the transfer function GV of the _voltage sampling circuit and the transfer function HV of the _voltage sampling circuit. Transfer functions of some controllers and control objects in the robot battery energy management control logic schematic diagram).

Table 1

Claims (10)

1. A wireless charging system for an underwater robot is characterized in that it comprises a main circuit and a control circuit, the main circuit includes a coupled transmitter main circuit and a receiver main circuit, and the transmitter main circuit includes sequentially connected transmitters A terminal DC power supply system, a transmitting terminal AC conversion system, and a transmitting terminal resonant circuit, and the receiving terminal main circuit includes a receiving terminal resonant circuit, a receiving terminal DC conversion circuit and a receiving terminal load matching conversion circuit connected in sequence; The control circuit includes a transmitter control circuit and a receiver control circuit, the transmitter control circuit includes a transmitter PWM drive circuit and a transmitter current sampling circuit respectively connected to the transmitter digital signal processor DSP, the transmitter current sampling circuit Connected on the resonant circuit at the transmitting end; the receiving end control circuit includes a receiving end PWM drive circuit connected respectively on the receiving end digital signal processor DSP, two voltage sampling circuits at the receiving end and a receiving end current sampling circuit, the receiving end The first voltage sampling circuit at the receiving end of the two-way voltage sampling circuit at the receiving end is connected to the output end of the DC conversion circuit at the receiving end, and the second voltage sampling circuit at the receiving end is connected in series between the positive pole and the negative pole of the battery of the underwater robot. The sampling circuit is connected in series between the positive pole O of the battery of the underwater robot and the positive pole P of the load matching conversion circuit at the receiving end. 2. The wireless charging system for underwater robots according to claim 1, wherein the AC conversion system at the transmitting end includes a first power MOS switch S1, a second power MOS switch S2, a third power MOS switch S3, the fourth power MOS switch tube S4; the drain of the first power MOS switch tube S1 and the drain of the third power MOS switch tube S3 are connected to the positive pole A of the transmitting end DC power supply system, and the drain of the first power MOS switch tube S1 The source is connected to the drain of the second power MOS switch S2, the source of the third power MOS switch S3 is connected to the drain of the fourth power MOS switch S4, the source of the second power MOS switch S2, the first The source of the four-power MOS switch S4 is connected to the negative pole B of the DC power supply system at the transmitter, the gate of the first power MOS switch S1 is connected to the first PWM signal terminal of the PWM drive circuit at the transmitter, and the second power MOS switch The gate of S2 is connected to the second PWM signal terminal of the PWM drive circuit at the transmitter, the gate of the third power MOS switch S3 is connected to the third PWM signal terminal of the PWM drive circuit at the transmitter, and the gate of the fourth power MOS switch S4 The gate is connected to the fourth PWM signal terminal of the PWM drive circuit at the transmitter. 3. The wireless charging system for an underwater robot according to claim 1 or 2, wherein the resonant circuit at the transmitting end comprises a resonant capacitor C1 at the transmitting end and a resonant inductor L1 at the transmitting end, and one end of the resonant capacitor C1 at the transmitting end is connected to The source of the first power MOS switch tube S1 is connected; the other end of the transmitter resonance capacitor C1 is connected to one end of the transmitter resonance inductor L1; the other end of the transmitter resonance inductor L1 is connected to the drain of the fourth power MOS switch tube S4 . 4. The underwater robot wireless charging system according to claim 1, characterized in that the receiving end DC conversion circuit includes a first diode VD1, a second diode VD2, a third diode VD3, a Four diodes VD4; the cathode of the first diode VD1, the cathode of the third diode VD3 are connected to one end of the third inductor L3, the anode of the first diode VD1 is connected to the cathode of the second diode VD2 , the anode of the third diode VD3 is connected to the cathode of the fourth diode VD4, the anode of the second diode VD2 is connected to the source of the fifth power MOS switch S5, and the anode of the fourth diode VD4 is connected. 5. The underwater robot wireless charging system according to claim 1 or 4, wherein the receiving end resonant circuit includes a receiving end resonant capacitor C2 and a receiving end resonant inductance L2, and one end of the receiving end resonant capacitor C2 is connected to the receiving end resonant capacitor C2. The anode of the first diode VD1 is connected, the other end is connected to one end of the receiving end resonant inductor L2, and the other end of the receiving end resonant inductor L2 is connected to the cathode of the fourth diode VD4. 6. The underwater robot wireless charging system according to claim 1, characterized in that the receiving end load matching circuit includes a third inductor L3, a fifth power MOS switch S5, a fifth diode VD5 and a third Capacitor C3, the third inductance C3 and the fifth diode VD5 are connected in series between the positive pole M output by the DC conversion circuit at the receiving end and the positive pole P of the robot battery interface, and the drain of the fifth power MOS switch tube S5 is connected to the first At the electrode point I between the three inductors C3 and the fifth diode VD5, the source of the fifth power MOS switch is connected to the negative pole N of the output of the DC conversion circuit at the receiving end, and the gate of the fifth power MOS switch is connected to the receiving terminal. A third capacitor C3 is connected in series between the positive pole P and the negative pole Q of the output of the fifth PWM signal terminal of the PWM driving circuit at the receiving end and the load matching conversion circuit at the receiving end. 7. A control method utilizing the underwater robot wireless charging system according to claim 1, characterized in that: First, detect the current of the resonant circuit at the transmitting end, and determine whether the receiving end is connected to the circuit through the current change of the resonant circuit at the transmitting end, that is, load detection. If the transmitting end detects that the receiving end is connected to the circuit, the digital signal processor DSP at the transmitting end sends out The charging command, the circuit enters the working state, controls the AC conversion system of the transmitting end to output AC through the PWM drive circuit of the transmitting end, and transmits the electric energy to the receiving end through the resonant circuit of the transmitting end, and the receiving end receives the energy transmitted by the transmitting end through the resonant circuit of the receiving end. And convert these energies into AC output, after passing through the DC conversion circuit at the receiving end and the load matching circuit at the receiving end, the battery of the underwater robot is charged. If the transmitter detects that the receiving end leaves the circuit or the battery of the underwater robot at the receiving end is fully , the digital signal processor DSP at the transmitting end issues an instruction to stop charging, and will control the main circuit at the transmitting end to return to the detection mode; Secondly, when the circuit is working, the current sampling circuit at the transmitting end samples the current of the resonant circuit at the transmitting end, usually samples the current of the resonant circuit at the transmitting end, compares the value of the sampling current with the zero value, and changes the The frequency of the PWM sent by the digital signal processor DSP at the transmitting end corrects the output frequency of the AC conversion system at the transmitting end to reach the resonant frequency of the resonant circuit at the transmitting end, that is, traces the resonant frequency; Furthermore, when the main circuit at the receiving end is working, the second voltage sampling circuit at the receiving end samples the battery voltage of the underwater robot, and the current sampling circuit at the receiving end samples the charging current of the battery of the underwater robot, and the collected voltage and current information Send it to the digital signal processor DSP at the receiving end, and process it in the digital signal processor DSP at the receiving end, so that according to the processing result, a corresponding PWM signal is sent to control the charging mode of the underwater robot at the receiving end to realize the charging of the underwater robot. Battery energy management. 8. The control method of the underwater robot wireless charging system according to claim 7, wherein the specific method of load detection is: When the main circuit of the transmitting end starts to initialize, the main circuit of the transmitting end runs in the detection mode and runs for 20 cycles every 1s. At the midpoint of each PWM wave, the current on the inductor in the resonant circuit of the transmitting end is sampled, and the middle sampling value is taken. , if the current at this time is less than 20 amperes, the main circuit of the transmitter will switch to continuous mode operation, if the current value is greater than 20 amperes at this time, then continue to run in detection mode, take the middle sampling value, and pass and the previous 1 second The sampling value is compared to determine the working mode of the circuit. If the amplitude of the current sampling value decreases by more than 2 amperes compared with the sampling value of the previous second, it proves that the main circuit of the receiving end is connected to the circuit, the circuit enters continuous mode operation, and the circuit continues to work. To charge the battery of the underwater robot, when running in continuous mode, the current on the transmitter inductor is sampled at the midpoint of the PWM every cycle, and the intermediate value is taken every second. At the same time, a comparison is made every second. If the current value increases by more than 2 amperes, the transmitter will stop working in the continuous mode and switch to the detection mode. If the change in current is within 1 ampere compared with the sampling value of the previous second, it proves that the receiver has no action. , the circuit maintains the previous mode of operation. 9. The control method of the underwater robot wireless charging system according to claim 7, wherein the method for tracking the resonant frequency is: sampling the current on the inductor in the resonant circuit at the transmitting end at the rising edge of each PWM, if If the sampling value is greater than zero, increase the frequency of the output voltage of the AC conversion system at the transmitter until the sampling value of the current is zero; if the sampling value is less than zero, reduce the frequency of the output voltage of the AC conversion system at the transmitter until the current sampling The value is zero; if the sampling value is equal to zero, the frequency of the output voltage of the AC conversion system at the transmitting end remains unchanged. 10. The control method of the underwater robot wireless charging system according to claim 7, wherein the battery energy management method of the underwater robot is as follows: when the battery power is lower than 50%, charging is performed, and when the battery current is higher than 90%. %, the charging is ended by the load matching converter, that is, when charging the underwater robot, the charging power of the battery is controlled to realize constant power charging, which is specifically realized by double-loop closed-loop control: sampling the voltage and charging current of the battery , compared with a given constant power, the error is integrated through the digital signal processor DSP to generate a reference value for the input voltage of the power matching converter; the input voltage of the power matching converter is controlled to control the output power, that is, the battery The charging power reaches a given constant power to realize constant power charging.