CN111224471B - Maximum efficiency tracking method for electric field coupling type underwater wireless power transmission system - Google Patents

Abstract

The invention discloses a maximum efficiency tracking method of an electric field coupling type underwater wireless power transmission system, which comprises the steps of firstly establishing a coupling capacitance model of the electric field coupling type underwater wireless power transmission system, and realizing the simulation of coupling capacitance based on an aqueous medium; then constructing an equivalent circuit model of a wireless power transmission unit of the electric field coupling type underwater wireless power transmission system, calculating an equivalent output resistance under the condition of maximum energy transmission efficiency, and searching a relation between the equivalent output resistance and a coupling capacitor under the condition of maximum energy transmission efficiency, so that the maximum energy transmission efficiency is constructed by detecting a coupling capacitor value; and finally, the switching frequency of the transmitting end full-bridge inverter circuit and the phase shift angle of the receiving end full-bridge rectifier circuit are adjusted in real time through the detected coupling capacitance value, so that the tracking of the maximum energy transmission efficiency of the wireless electric energy transmission system is realized. The invention solves the problem of unstable charging power of the underwater equipment in the prior art caused by ocean current, water pressure, temperature, salinity and other factors.

Description

Maximum efficiency tracking method of electric field coupled underwater wireless power transmission system

Technical field

The invention belongs to the technical field of wireless power transmission, and specifically relates to a maximum efficiency tracking method of an electric field coupled underwater wireless power transmission system.

Background technique

Today, a major technical challenge facing the construction and long-term operation and maintenance of large-scale underwater intelligent systems and military facilities (such as underwater sensors, ocean monitoring systems, and autonomous underwater vehicles (AUVs)) is the lack of safe and reliable energy supply. Especially under deep-sea conditions, compared with other power transmission methods (replacing batteries and cables), the wireless power transmission system has significant advantages of high reliability and high safety, and is more suitable for application in autonomous underwater vehicles or other underwater platforms. Therefore, research on key technologies of underwater wireless power transmission systems plays a vital role in realizing the country’s strategy of “marine power”.

The marine environment is a complex and ever-changing environment. Factors such as temperature, salinity, and weather in the ocean will directly affect the safe operation of the underwater wireless power transmission system. For example, when the angle or distance between the transmitter coil and the receiver coil of the wireless power transmission system changes due to the external environment or the movement of the underwater vehicle itself, the power transmission of the underwater wireless power transmission system will be greatly affected. Therefore, how to achieve stable and safe operation of the wireless power transmission system is the key to the problem that the underwater wireless power transmission system needs to solve. In the underwater environment, electric energy resources are extremely limited. How to maximize the utilization of electric energy resources is also an urgent problem that needs to be solved. With the development of science and technology and the implementation of national marine strategies, autonomous underwater vehicles have been increasingly widely used in fields such as ocean survey, military, scientific and industrial exploration. At this stage, the main charging methods for autonomous underwater vehicles are physical cables, manual battery replacement, and wireless power transmission systems based on submarine base stations. Compared with physical cables and manual battery replacement, the underwater wireless power transmission system can efficiently and conveniently charge autonomous underwater vehicles. The currently adopted underwater wireless power transmission systems are mainly based on magnetic field induction or magnetic field coupling resonant wireless power transmission systems. However, the inductor coil will produce eddy current losses in conductive fresh water or sea water, which will continue to increase as the frequency increases. In addition, the inductor coil is sensitive to surrounding metal, which will seriously affect the safety of wireless charging of autonomous underwater vehicles.

The electric field-coupled wireless power transmission system has been proven to be capable of efficient, long-distance, and high-power wireless power transmission. It has no eddy current loss in seawater and is insensitive to longitudinal angle deviation. In addition, the electric field coupling wireless power transmission system is not greatly affected by the surrounding metal during operation. Because the relative dielectric constant of seawater medium is about 72 times that of air medium (water temperature is 25 degrees, seawater salinity is 35‰, frequency is below 2G Hz). Therefore, compared with the air medium, its underwater power transmission capability will be greatly enhanced. In addition, using only metal plates as the medium for wireless power transmission will reduce costs to a great extent. Therefore, the electric field coupled wireless power transmission system will have bright application prospects in underwater wireless power transmission. However, there is still a lack of research on the coupling capacitance model and maximum efficiency tracking algorithm of the electric field coupled wireless power transmission system based on seawater medium. These aspects of work will realize the dynamic and high-efficiency operation of underwater wireless power. Therefore, these studies will have a key impact on the safe and stable operation of wireless power transmission systems.

Against this background, the patent of this invention proposes a maximum efficiency tracking method for an electric field coupled underwater wireless power transmission system.

Contents of the invention

The purpose of the present invention is to provide a maximum efficiency tracking method for an electric field-coupled underwater wireless power transmission system, which solves the problem of charging power caused by underwater equipment in the prior art due to ocean currents, water pressure, temperature, salinity and other factors. Unstable issues.

The technical solution adopted by the present invention is a maximum efficiency tracking method for an electric field coupled underwater wireless power transmission system, which is specifically implemented in accordance with the following steps:

Step 1. Establish a coupling capacitance model of the electric field coupling underwater wireless power transmission system to simulate the coupling capacitance based on water media;

Step 2. Construct an equivalent circuit model of the wireless power transmission unit of the electric field coupled underwater wireless power transmission system to calculate the equivalent output resistance under the maximum energy transmission efficiency and find the equivalent output resistance and coupling under the maximum energy transmission efficiency. The relationship between capacitances, thereby constructing the maximum energy transfer efficiency by detecting the coupling capacitance value;

Step 3. Use the detected coupling capacitance value to adjust the switching frequency of the full-bridge inverter circuit at the transmitting end and the phase shift angle of the full-bridge rectifier circuit at the receiving end in real time, thereby achieving tracking of the maximum energy transfer efficiency of the wireless power transmission system.

The present invention is also characterized in that,

The specific structure of the coupling capacitor model of the electric field coupled underwater wireless power transmission system in step 1 is: including a full-bridge inverter circuit and a full-bridge rectifier circuit connected through the coupling capacitor. In the full-bridge inverter circuit, Vin is the wireless power transmission system Power supply, S ₁₁ ~ S ₁₄ are four power switch tubes of the full-bridge inverter circuit, among which S ₁₁ and S ₁₄ form a bridge arm, and S ₁₂ and S ₁₃ form a bridge arm;

In the coupling capacitor, P ₁ ~ P ₄ are the four metal plates that constitute the coupling capacitor. Among them, P ₁ and P ₄ are the transmitting end metal plates, and P ₂ and P ₃ are the receiving end metal plates;

In the full-bridge rectifier circuit, S ₂₁ to S ₂₄ are the four power switch tubes of the full-bridge rectifier circuit. Among them, S ₂₁ and S ₂₄ form a bridge arm, and S ₂₂ and S ₂₃ form a bridge arm;

L _P is the resonant inductance of the primary side resonant network. The resonant inductor L _P is connected between the power switch tube S ₁₁ and the transmitting end metal plate P ₁ . L _S is the resonant inductance of the secondary side resonant network. The resonant inductor L _S is connected to the receiving end. Between the terminal metal plate P ₂ and the power switch tube S ₂₁ ;

The entire structure is powered by the battery V _battery .

The equivalent circuit of the coupling capacitor in step 2 is as follows:

Assume that the equivalent capacitance of the primary side of the coupling capacitor is C _P , the equivalent voltage is _VP , and the equivalent current is I _P ; the primary side of the coupling capacitor is equivalent to a current source, and the current of the equivalent current source is I = jωC _M V _S , assuming that the equivalent capacitance of the secondary side of the coupling capacitor is C _S , the equivalent voltage is V _S , and the equivalent current is I _S , the secondary side of the coupling capacitor is equivalent to a current source and the equivalent current source current is I = jωC _M V _P ;

The relationship between the capacitive coupling coefficient k _c and the coupling capacitance C _M is expressed by the following formula:

The equivalent circuit model of the wireless power transmission unit of the capacitive underwater wireless power transmission system in step 2 is as follows:

Including the wireless power transmission system power supply Us, the equivalent voltage _VP of the primary resonant network, _{the equivalent inductance LP of the primary resonant network, the equivalent resistance R P of} the primary resonant network, the equivalent resistance C _P of the primary resonant network, etc. The current of the effective current source is I=jωC _M V _S ;

Assume the equivalent voltage V _S of the secondary resonant network, the equivalent resistance R _S of the secondary resonant network, the equivalent inductance L _S of the secondary resonant network, the equivalent capacitance C _S of the secondary resonant network, and the equivalent output resistance R _Leq , then:

The maximum power transmission efficiency of electric field coupled wireless power transmission satisfies the formula:

Let α=[jωC _p C _s -jω(C _M ) ² ], β=(jωL _s +R _s )[jωC _p C _s -jω(C _M ) ² ]+C _p , γ=β ² R _p + (C _M ) ² R _s , α, β, r are intermediate substitution amounts;

Formula (3) is simplified to:

Among them, C _M is the coupling capacitance, R _Leq is the equivalent output resistance, and R _p is the equivalent resistance of the primary resonant network;

Formula (4) is the formula for the maximum power transmission efficiency of the electric field coupling wireless power transmission system;

Derive the equivalent output resistance R _Leq in formula (4). Under the condition of maximum power transmission efficiency, the equivalent output resistance R _Leq is expressed as:

Among them, R _p is the equivalent resistance of the primary side resonant network, C _M is the coupling capacitance, and R _s is the equivalent resistance of the secondary side resonant network.

Step 3 is detailed as follows:

Assume that the phase shift angle of the full-bridge rectifier circuit at the receiving end in the coupling capacitor model of the electric field coupled underwater wireless power transmission system in step 1 is θ, and the relationship between the load resistance R _L and the equivalent output resistance R _Leq is expressed as:

Combining formulas (5) and (6), it can be concluded that the relationship between the coupling capacitance C _M and the phase shift angle θ is:

The coupling capacitance C _M has the following relationship with the primary resonant voltage V _p and the secondary resonant voltage V _s :

In the formula: k ₃ =C _s , V _s is the voltage of the secondary resonant network, V _p is the voltage of the primary resonant network, C _s is the equivalent capacitance of the secondary resonant network, L _s is the equivalent inductance of the secondary resonant network, R _s is the equivalent resistance of the secondary resonant network, R _Leq is the equivalent output resistance;

It can be seen from formulas (7) and (8) that as long as the primary side resonance voltage V _p and the secondary side resonance voltage V _s of the resonant network are detected, the coupling capacitance C _M can be calculated. When the load resistance R _L is determined and the coupling When the capacitance C _M changes in real time, the phase shift angle θ of the full-bridge rectifier circuit can be adjusted in real time to make formula (7) always true. Combined with the real-time adjustment of the frequency of the resonant network at the transmitter, the maximum power transmission efficiency can be obtained.

The beneficial effects of the present invention are: (1) The coupled capacitive underwater wireless power transmission system of the present invention has no eddy current loss and is insensitive to surrounding metals. It is very suitable for underwater wireless charging scenarios and can operate with high power and high efficiency; (2) In a dynamic underwater environment, underwater equipment can be charged stably. The coupling capacitance model based on conductive water media (including seawater media) is used to track the maximum power transmission efficiency, thereby achieving the maximum energy transmission efficiency of the system; (3) The coupling capacitive underwater wireless power transmission system can achieve the maximum power transmission efficiency using only metal plates. Charging of underwater equipment can greatly reduce the cost of underwater wireless power transmission systems; (4) the maximum efficiency tracking method proposed by the present invention can be widely used in the field of underwater wireless charging or other fields, Expand the live operation time and working range of underwater equipment.

Description of the drawings

Figure 1 is an electric field coupled underwater wireless power transmission system topology applied in the present invention;

Figure 2 is an equivalent circuit of the coupling capacitor topology used in the present invention;

Figure 3 is the equivalent circuit of the wireless power transmission unit involved in the present invention.

Detailed ways

The present invention will be described in detail below with reference to the drawings and specific embodiments.

The invention proposes an electric field coupling wireless power transmission system for autonomous underwater vehicles. The electric field coupling wireless power transmission system has a certain ability to suppress charging power instability caused by lateral offset or misalignment of the charging coupling unit. Therefore, in a dynamic seawater environment, a stable charging process of autonomous vehicle lithium batteries can be achieved. The maximum energy transmission efficiency is achieved by tracking the maximum power transmission efficiency based on the electric field coupling wireless power transmission system. The topological structure of the electric field coupling wireless transmission system used is shown in Figure 1 (the simple resonant network circuit used in the figure, the patent of this invention is also applicable to other topologies).

Maximum efficiency tracking of wireless power transmission systems is a key technology to achieve effective utilization of limited power under the sea. The patent of this invention studies the maximum efficiency tracking strategy of the electric field coupled underwater wireless power transmission system based on the seawater coupling capacitance model. The content includes: establishing an equivalent circuit based on the electric field coupled wireless power transmission system. The equivalent output resistance model under the maximum power transmission efficiency is derived based on the equivalent circuit. Under the condition of calculating the maximum power transmission efficiency, the relationship between the equivalent output resistance and the coupling capacitance is used to achieve the maximum power efficiency tracking algorithm by indirectly adjusting the coupling capacitance. Combining the control module and the seawater coupling capacitance model, a maximum efficiency tracking control strategy is established to achieve maximum efficiency tracking of the coupled capacitive underwater wireless power transmission system.

The maximum efficiency tracking method of the electric field coupled underwater wireless power transmission system of the present invention is specifically implemented according to the following steps:

Step 1. Establish a coupling capacitance model of the electric field coupling underwater wireless power transmission system, as shown in Figure 1, to simulate the coupling capacitance based on water media;

Step 2. Construct an equivalent circuit model of the wireless power transmission unit of the electric field coupled underwater wireless power transmission system to calculate the equivalent output resistance under the maximum energy transmission efficiency and find the equivalent output resistance and coupling under the maximum energy transmission efficiency. The relationship between capacitances, thereby constructing the maximum energy transfer efficiency by detecting the coupling capacitance value;

Step 3. Use the detected coupling capacitance value to adjust the switching frequency of the full-bridge inverter circuit at the transmitting end and the phase shift angle of the full-bridge rectifier circuit at the receiving end in real time, thereby achieving tracking of the maximum energy transfer efficiency of the wireless power transmission system.

Among them, as shown in Figure 2 and Figure 3, the specific structure of the coupling capacitor model of the electric field coupled underwater wireless power transmission system in step 1 is: including a full-bridge inverter circuit and a full-bridge rectifier circuit connected through the coupling capacitor. In the inverter circuit, Vin is the power supply of the wireless power transmission system, S ₁₁ ~ S ₁₄ are the four power switch tubes of the full-bridge inverter circuit, among which S ₁₁ and S ₁₄ form a bridge arm, and S ₁₂ and S ₁₃ form a bridge arm. ;

In the coupling capacitor, P ₁ ~ P ₄ are the four metal plates that constitute the coupling capacitor. Among them, P ₁ and P ₄ are the transmitting end metal plates, and P ₂ and P ₃ are the receiving end metal plates;

In the full-bridge rectifier circuit, S ₂₁ to S ₂₄ are the four power switch tubes of the full-bridge rectifier circuit. Among them, S ₂₁ and S ₂₄ form a bridge arm, and S ₂₂ and S ₂₃ form a bridge arm;

L _P is the resonant inductance of the primary side resonant network. The resonant inductor L _P is connected between the power switch tube S ₁₁ and the transmitting end metal plate P ₁ . L _S is the resonant inductance of the secondary side resonant network. The resonant inductor L _S is connected to the receiving end. Between the terminal metal plate P ₂ and the power switch tube S ₂₁ ;

The entire structure is powered by the battery V _battery .

The equivalent circuit of the coupling capacitor in step 2 is as follows:

Assume that the equivalent capacitance of the primary side of the coupling capacitor is C _P , the equivalent voltage is _VP , and the equivalent current is I _P ; the primary side of the coupling capacitor is equivalent to a current source, and the current of the equivalent current source is I = jωC _M V _S , assuming that the equivalent capacitance of the secondary side of the coupling capacitor is C _S , the equivalent voltage is V _S , and the equivalent current is I _S , the secondary side of the coupling capacitor is equivalent to a current source and the equivalent current source current is I = jωC _M V _P ;

The relationship between the capacitive coupling coefficient k _c and the coupling capacitance C _M is expressed by the following formula:

The equivalent circuit model of the wireless power transmission unit of the capacitive underwater wireless power transmission system in step 2 is as follows:

Including the wireless power transmission system power supply Us, the equivalent voltage _VP of the primary resonant network, _{the equivalent inductance LP of the primary resonant network, the equivalent resistance R P of} the primary resonant network, the equivalent resistance C _P of the primary resonant network, etc. The current of the effective current source is I=jωC _M V _S ;

Assume the equivalent voltage V _S of the secondary resonant network, the equivalent resistance R _S of the secondary resonant network, the equivalent inductance L _S of the secondary resonant network, the equivalent capacitance C _S of the secondary resonant network, and the equivalent output resistance R _Leq , then:

The maximum power transmission efficiency of electric field coupled wireless power transmission satisfies the formula:

Let α=[jωC _p C _s -jω(C _M ) ² ], β=(jωL _s +R _s )[jωC _p C _s -jω(C _M ) ² ]+C _p , γ=β ² R _p + (C _M ) ² R _s , α, β, r are intermediate substitution amounts;

Formula (3) is simplified to:

Among them, C _M is the coupling capacitance, R _Leq is the equivalent output resistance, and R _p is the equivalent resistance of the primary resonant network;

Formula (4) is the formula for the maximum power transmission efficiency of the electric field coupling wireless power transmission system;

Derive the equivalent output resistance R _Leq in formula (4). Under the condition of maximum power transmission efficiency,

The equivalent output resistance R _Leq is expressed as:

Among them, R _p is the equivalent resistance of the primary side resonant network, C _M is the coupling capacitance, and R _s is the equivalent resistance of the secondary side resonant network.

Step 3 is detailed as follows:

Assume that the phase shift angle of the full-bridge rectifier circuit at the receiving end in the coupling capacitor model of the electric field coupled underwater wireless power transmission system in step 1 is θ, and the relationship between the load resistance R _L and the equivalent output resistance R _Leq is expressed as:

Combining formulas (5) and (6), it can be concluded that the relationship between the coupling capacitance C _M and the phase shift angle θ is:

The coupling capacitance C _M has the following relationship with the primary resonant voltage V _p and the secondary resonant voltage V _s :

In the formula: k ₃ =C _s , V _s is the voltage of the secondary resonant network, V _p is the voltage of the primary resonant network, C _s is the equivalent capacitance of the secondary resonant network, L _s is the equivalent inductance of the secondary resonant network, R _s is the equivalent resistance of the secondary resonant network, R _Leq is the equivalent output resistance;

It can be seen from formulas (7) and (8) that as long as the primary side resonance voltage V _p and the secondary side resonance voltage V _s of the resonant network are detected, the coupling capacitance C _M can be calculated. When the load resistance R _L is determined and the coupling When the capacitance C _M changes in real time, the phase shift angle θ of the full-bridge rectifier circuit can be adjusted in real time to make formula (7) always true. Combined with the real-time adjustment of the frequency of the resonant network at the transmitter, the maximum power transmission efficiency can be obtained.

The present invention proposes a maximum efficiency tracking method for an electric field coupled underwater wireless power transmission system, which can achieve stable and efficient operation of the wireless power transmission system in a dynamic underwater environment.

Claims (1)

1. The maximum efficiency tracking method of the electric field coupling type underwater wireless power transmission system is characterized by comprising the following steps of:

step 1, a coupling capacitance model of an electric field coupling type underwater wireless power transmission system is established, and simulation of coupling capacitance based on an aqueous medium is realized;

the specific structure of the coupling capacitance model of the electric field coupling type underwater wireless power transmission system in the step 1 is as follows: comprises a full-bridge inverter circuit and a full-bridge rectifier circuit which are connected through a coupling capacitor, wherein Vin in the full-bridge inverter circuit is a power supply of a wireless power transmission system, and S ₁₁ ～S ₁₄ Four power switching tubes of the full-bridge inverter circuit, wherein S ₁₁ And S is ₁₄ Form a bridge arm S ₁₂ And S is ₁₃ Forming a bridge arm;

in the coupling capacitor, P ₁ ～P ₄ Four metal plates for forming coupling capacitor, wherein P ₁ And P ₄ Is a transmitting end metal plate, P ₂ And P ₃ Is a receiving end metal plate;

in the full bridge rectifier circuit, S ₂₁ ～S ₂₄ Four power switch tubes of the full-bridge rectifying circuit, wherein S ₂₁ And S is ₂₄ Form a bridge arm S ₂₂ And S is ₂₃ Forming a bridge arm;

L _P is the resonance inductance of the primary resonance network, the resonance inductance L _P Is connected to a power switch tube S ₁₁ And a transmitting-end metal plate P ₁ Between, L _S Resonance inductance L is the resonance inductance of the secondary resonance network _S Connected to the receiving end metal plate P ₂ And a power switch tube S ₂₁ Between them;

the whole structure consists of a battery V _battery Supplying power;

step 2, constructing an equivalent circuit model of a wireless power transmission unit of the electric field coupling type underwater wireless power transmission system, so as to calculate an equivalent output resistance under the condition of maximum energy transmission efficiency, and searching a relation between the equivalent output resistance and a coupling capacitor under the condition of maximum energy transmission efficiency, thereby constructing maximum energy transmission efficiency by detecting a coupling capacitor value;

the equivalent circuit of the coupling capacitor in the step 2 is specifically as follows:

let the equivalent capacitance of the primary side of the coupling capacitor be C _P Equivalent voltage of V _P Equivalent current is I _P The method comprises the steps of carrying out a first treatment on the surface of the The primary side of the coupling capacitor is equivalent to a current source, and the current of the equivalent current source is I=jωC _M V _S Let the secondary equivalent capacitance of the coupling capacitor be C _S Equivalent voltage of V _S Equivalent current is I _S The secondary side of the coupling capacitor is equivalent to a current source equivalent current source current of I=jωC _M V _P ；

Capacitive coupling coefficient k _c And coupling capacitor C _M The relationship that exists is expressed by the following formula:

the equivalent circuit model of the wireless power transmission unit of the capacitive underwater wireless power transmission system in the step 2 is specifically as follows:

comprising a power supply Us of a wireless power transmission system and an equivalent voltage V of a primary side resonance network _P Primary side resonant network equivalent inductance L _P Equivalent resistance R of primary side resonance network _P Equivalent resistance C of primary side resonance network _P The current of the equivalent current source is i=jωc _M V _S ；

Set equivalent voltage V of secondary side resonance network _S Equivalent resistance R of secondary side resonance network _S Equivalent inductance L of secondary side resonant network _S Equivalent capacitance of secondary side resonant networkC _S Equivalent output resistance R _Leq Then:

the maximum electric energy transmission efficiency of electric field coupling type wireless electric energy transmission meets the formula:

let α= [ jωc ] _p C _s -jω(C _M ) ² ]，β＝(jωL _s +R _s )[jωC _p C _s -jω(C _M ) ² ]+C _p ，

γ＝β ² R _p +(C _M ) ² R _s Alpha, beta and r are intermediate substitution amounts;

the formula (3) is simplified to obtain:

wherein C is _M R is a coupling capacitance _Leq R is equivalent to output resistance _p The equivalent resistance of the primary resonance network;

equation (4) is the maximum power transmission efficiency equation of the electric field coupling type wireless power transmission system;

for the equivalent output resistance R in formula (4) _Leq Deriving, in the case of maximum power transfer efficiency,

equivalent output resistance R _Leq Expressed as:

wherein R is _p Is the equivalent resistance of the primary side resonance network, C _M R is a coupling capacitance _s The equivalent resistance of the secondary resonance network;

step 3, the switching frequency of the transmitting end full-bridge inverter circuit and the phase shift angle of the receiving end full-bridge rectifier circuit are adjusted in real time through the detected coupling capacitance value, so that the tracking of the maximum energy transmission efficiency of the wireless electric energy transmission system is realized, and the step 3 is specifically as follows:

setting the phase shift angle of a receiving end full-bridge rectifier circuit in a coupling capacitance model of the electric field coupling type underwater wireless power transmission system in the step 1 as theta, and loading a resistor R _L And equivalent output resistance R _Leq The relationship between them is expressed as:

by combining the formulas (5) and (6), the coupling capacitance C is obtained under the condition of maximum electric energy transmission power _M The relationship with the phase shift angle θ is:

coupling capacitor C _M With primary resonance voltage V _p And secondary resonance voltage V _s The following relationships are satisfied:

wherein:k ₃ ＝C _s ，V _s for secondary resonance network voltage, V _p For primary resonance network voltage, C _s Is the equivalent capacitance of the secondary resonance network, L _s Is equivalent inductance of secondary resonance network, R _s Is the equivalent resistance of the secondary resonance network, R _Leq Is an equivalent output resistance;

as can be seen from formulas (7) and (8), as long as the primary resonance voltage V of the resonance network is detected _p And secondary resonance voltage V _s The coupling capacitance C can be calculated _M When the load resistor R _L Determining whenCoupling capacitor C _M When the power transmission efficiency is changed in real time, the phase shift angle theta of the full-bridge rectifying circuit can be adjusted in real time to enable the formula (7) to be constant, and the maximum power transmission efficiency is obtained by combining the real-time adjustment of the resonant network frequency of the transmitting end.