CN105305658B - Wireless power transmission methods, devices and systems - Google Patents

Abstract

The invention discloses a wireless energy transmission method, device and system, wherein the method includes: the transmitting device transmits the energy corresponding to the obtained alternating current to the transmitting coil in the transmitting device through the exciting coil in the transmitting device; Transmitting electric energy to the receiving device, the electric energy is generated by the transmitting coil according to the energy; wherein, the wire diameter of the transmitting coil is proportional to the cube of the transmission distance divided by the radius of the transmitting coil, and is respectively related to the vacuum magnetic permeability, the first transmission coil The conductivity and the first resonant angular frequency of the transmitting coil are directly proportional to the power of negative one-half; the distance between the transmitting device and the receiving device is the transmission distance. When the transmitting coil adopts the above wire diameter, the entire power transmission system can be in a critical coupling state, so that the transmission efficiency can be significantly improved.

Description

Wireless power transmission method, device and system

technical field

The present invention relates to power transmission technology, in particular to a wireless power transmission method, device and system.

Background technique

As an indispensable source of energy in people's lives, electric energy is mainly transmitted through wires. So far, the status of this transmission method is still irreplaceable. However, with the vigorous development of science and technology, the traditional power supply methods have become increasingly unable to meet the actual needs of production and life, and modern people's demand for wireless power transmission is becoming more and more urgent.

At present, the magnetic coupling resonant wireless power transmission is an implementation method of wireless power transmission. Specifically, the magnetically coupled resonant wireless energy utilizes the principle of resonance, so that it can still obtain high efficiency and high power when transmitting at a medium distance (the transmission distance is generally several times the diameter of the transmission coil), and the power transmission Not affected by non-magnetic obstacles in space, it has the advantages of longer transmission distance, less impact on the electromagnetic environment, and higher power.

However, in the wireless power transmission method in the prior art, the energy transmission efficiency of the wireless power transmission system is not always at the maximum value, and the energy transmission efficiency is low. Therefore, there is an urgent need for a wireless power transmission method that can improve energy transmission efficiency during wireless power transmission.

Contents of the invention

The purpose of the present invention is to provide a wireless power transmission method, device and system to solve the problem that the energy transmission efficiency of the wireless power transmission method in the prior art is not always at the maximum value and the energy transmission efficiency is low.

To achieve the above object, the present invention provides a wireless power transmission method, including:

The transmitting device transfers the energy corresponding to the obtained alternating current to the transmitting coil in the transmitting device through the exciting coil in the transmitting device;

The transmitting device transmits electric energy to the receiving device through the transmitting coil, and the electric energy is generated by the transmitting coil according to the energy;

Wherein, the wire diameter of the transmitting coil is directly proportional to the cube of the transmission distance divided by the radius of the transmitting coil, and is respectively proportional to the vacuum magnetic permeability, the first electrical conductivity of the transmitting coil, and the negative of the first resonant angular frequency of the transmitting coil. One-half power is proportional; the distance between the transmitting device and the receiving device is the transmission distance.

Another aspect of the present invention also provides a wireless power transmission method, including:

The receiving device receives the electric energy transmitted by the transmitting device through the receiving coil of the receiving device;

The receiving device transmits the electric energy to the load coil in the receiving device through the receiving coil;

Wherein, the wire diameter of the receiving coil is proportional to the cube of the transmission distance divided by the radius of the receiving coil, and is respectively proportional to the vacuum magnetic permeability, the second electrical conductivity of the receiving coil, and the negative of the second resonant angular frequency of the receiving coil. One-half power is proportional;

The distance between the transmitting device and the receiving device is the transmission distance.

Another aspect of the present invention provides a wireless power transmission device, including:

An exciting coil for transferring energy corresponding to the obtained alternating current to the transmitting coil, and for transmitting electric energy generated according to the energy to the transmitting coil of the wireless energy receiving device;

Wherein, the wire diameter of the transmitting coil is directly proportional to the cube of the transmission distance divided by the radius of the transmitting coil, and is respectively proportional to the vacuum magnetic permeability, the first electrical conductivity of the transmitting coil, and the negative of the first resonant angular frequency of the transmitting coil. One-half power is proportional;

The distance between the transmitting device and the receiving device is the transmission distance.

Another aspect of the present invention provides a wireless power transmission device, including:

a receiving coil for receiving the electric energy transmitted by the transmitting device, and a load coil for receiving the electric energy transmitted by the receiving coil;

Wherein, the wire diameter of the receiving coil is proportional to the cube of the transmission distance divided by the radius of the transmitting coil, and is proportional to the negative half of the second vacuum permeability, the second electrical conductivity, and the second resonant angular frequency, respectively. The square is proportional;

The distance between the transmitting device and the receiving device is the transmission distance.

Another aspect of the present invention provides a wireless power transmission system, including: any wireless power transmitting device on the market and any of the above wireless power receiving devices, wherein the wire diameter of the transmitting coil is equal to the wire diameter of the receiving coil, and the first The resonant angular frequency is equal to the second resonant angular frequency, the first conductivity is equal to the second conductivity, and the radius of the transmitting coil is equal to the radius of the receiving coil.

It can be seen from the above technical solutions that in the wireless power transmission method, device and system provided by the present invention, when the transmission distance D between the transmitting device and the receiving device is fixed, and the material, coil radius and resonant operating frequency of the receiving coil are fixed , at this time, if the wire diameter of the receiving coil is proportional to the cube of the transmission distance divided by the radius of the receiving coil, and is respectively proportional to the negative half power of the vacuum permeability, the second electrical conductivity, and the second resonant angular frequency When proportional, when the receiving device receives the electric energy transmitted by the transmitting device, the entire electric energy transmission system is in a critical coupling state, so that the transmission efficiency is significantly improved.

Description of drawings

FIG. 1 is a flowchart of a wireless power transmission method provided by an embodiment of the present invention;

Fig. 2 is a flowchart of a wireless power transmission method provided by another embodiment of the present invention;

3 is an equivalent circuit diagram of a transmitting device and a receiving device provided by an embodiment of the present invention;

FIG. 4 is a flow chart of a wireless power transmission method provided in another embodiment of the present invention;

FIG. 5 is a flow chart of a wireless power transmission method provided in yet another embodiment of the present invention;

FIG. 6 is a schematic circuit diagram of a wireless energy transmitting device provided in another embodiment of the present invention;

Fig. 7 is a schematic circuit diagram of a wireless power receiving device according to another embodiment of the present invention.

Detailed ways

Embodiment one

Fig. 1 is a flowchart of a wireless power transmission method provided by an embodiment of the present invention. The execution subject of this embodiment is a transmitting device. As shown in Fig. 1, the wireless power transmission method includes:

Step 101, the transmitting device transmits the energy corresponding to the acquired alternating current to the transmitting coil in the transmitting device through the excitation coil in the transmitting device, wherein the wire diameter of the transmitting coil is proportional to the cube of the transmission distance divided by the radius of the transmitting coil, and They are respectively proportional to the vacuum magnetic permeability, the first conductivity of the transmitting coil, and the negative half power of the first resonant angular frequency of the transmitting coil. The distance between the transmitting device and the receiving device is the transmission distance.

Among them, the first conductivity is determined by the material of the transmitting coil, the transmitting coil can be copper wire or aluminum wire, the transmission distance and the radius of the transmitting coil can be selected according to actual needs, for example, the transmission distance can be selected as 50 cm, in order to limit the emission The volume of the device, the radius of the transmitting coil can be selected as 10 cm.

Step 102, the transmitting device transmits electric energy to the receiving device through the transmitting coil, and the electric energy is generated by the transmitting coil according to the energy.

Specifically, the excitation coil is composed of an excitation source and a single-turn coil. Between the exciting coil and the transmitting coil, energy is transferred from the exciting coil to the transmitting coil through a direct coupling relationship. Wherein, the transmitting coil of the transmitting device should be placed coaxially with the receiving coil of the receiving device.

It can be seen that when the transmission distance D between the transmitting device and the receiving device is fixed, and the material, coil radius and resonant operating frequency of the transmitting coil have been fixed, if the wire diameter of the transmitting coil is divided by the transmission distance by the transmitting coil is proportional to the cube of the radius, and is proportional to the negative half power of the vacuum magnetic permeability, the first electrical conductivity, and the first resonant angular frequency respectively, then it can make the transmitting device transmit electric energy to the receiving device when the transmitting device Being in a critical coupling state, the transmission efficiency is significantly improved.

Embodiment two

Fig. 2 is a flowchart of a wireless power transmission method provided by another embodiment of the present invention. As shown in Fig. 2, the wireless power transmission method includes:

Step 201 , the transmitting device transmits the energy corresponding to the acquired alternating current to the transmitting coil in the transmitting device through the excitation coil in the transmitting device. Wherein, the wire diameter a1 _of the transmitting coil satisfies the following formula:

Among them, D is the transmission distance, μ ₀ is the vacuum magnetic permeability, ω ₁ is the first resonant angular frequency, σ ₁ is the first electrical conductivity, and r ₁ is the radius of the transmitting coil.

According to the above formula, it can be deduced that That is, the wire diameter of the transmitting coil is proportional to the cube of the transmission distance divided by the radius of the transmitting coil, and is respectively negative half of the vacuum magnetic permeability, the first conductivity of the transmitting coil, and the first resonant angular frequency of the transmitting coil. The first square is proportional.

Step 202, the transmitting device transmits electric energy to the receiving device through the transmitting coil, and the electric energy is generated by the transmitting coil according to the energy.

In order to facilitate understanding of the technical solution provided in this embodiment, the method for obtaining the above formula is given below.

Specifically, for the transmitting device, the circuit of the excitation coil can be reflected to the transmitting coil, which is equivalent to adding an induced electromotive force to the transmitting coil. For the receiving device, the receiving device includes a receiving coil and a load coil, which can reflect the load coil to the receiving coil, which is equivalent to adding a reflection impedance to the receiving coil. Fig. 3 is the equivalent circuit diagram of the transmitting device and the receiving device provided by an embodiment of the present invention, according to the analysis of the equivalent circuit diagram of Fig. 3, the following formula can be obtained:

Among them, U _S is the induced electromotive force equivalent to the transmitting coil from the exciting coil of the transmitting device, is the amplitude vector of U _S , R ₁ is the sum of the internal resistance of the excitation source of the exciting coil and the first equivalent capacitance of the exciting coil equivalent to the impedance of the transmitting coil, R ₂ is the second loss resistance of the transmitting coil, the second Radiation resistance and the sum of the first loss resistance of the exciting coil and the impedance of the first radiation resistance; M ₂₃ is the mutual inductance coefficient between the transmitting coil and the receiving coil, R ₃ is the third loss resistance of the receiving coil, the third radiation resistance and The sum of the fourth loss resistance of the load coil and the _fourth radiation resistance, R4 is the sum of the load of the load coil of the receiving device and the impedance of the fourth equivalent capacitance equivalent to the receiving coil. L ₂ is the second inductance of the transmitting coil, L ₃ is the third inductance of the receiving coil, C ₂ is the second equivalent capacitance of the transmitting coil, and C ₃ is the third equivalent capacitance of the receiving coil. j is the imaginary unit, I ₁ is the current flowing through the transmitter, is the amplitude vector of I ₁ , I ₂ is the current flowing through the receiving device, is the amplitude vector of I ₂ , ω is the angular frequency of the transmitter or receiver, and the current directions of I ₁ and I ₂ are clockwise in Figure 3.

Optionally, the transmitting device and the receiving device can be designed to have the same size and mechanical structure. In this case, R ₁ +R ₂ =R ₂ +R ₃ , L ₂ =L ₃ , C ₂ =C ₃ , where, Let R ₁ +R ₂ =R ₂ +R ₃ =R, L ₂ =L ₃ =L, C ₂ =C ₃ =C, M ₂₃ =M, and introduce a generalized detuning factor ξ:

in, Q is the quality factor, _ω0 is the resonant frequency, and then according to the formula (1), the following equation can be obtained:

Further, define the coupling factor η, where, Then the voltage received by the receiving device can be obtained according to formula (2):

Wherein, U is the receiving voltage of the electric energy received by the load of the receiving device, is the vector representation of U.

According to the received voltage U, the modulus value of the received voltage can be obtained as:

Among them, |U| is the modulus value of U.

Take the derivative of the modulus |U| of the received voltage, so that It can be obtained that at ξ ₁ =0 and The extreme value of the received voltage modulus is obtained at the place, and the extreme value |U _max | of the received voltage modulus is:

Then, the received voltage of the electric energy received by the load of the receiving device is normalized. The specific normalization method is to divide the received voltage modulus by the extreme value of the received voltage modulus to obtain the normalized voltage α as:

According to the analysis of formula (5), it can be known that when ξ=0, that is, when the transmitter works at the resonant frequency ω=ω ₀ :

and in , the voltage received by the load of the receiving device is the maximum value;

At η>1, there will be a phenomenon of frequency splitting, that is, there will be two different resonant frequencies in the process of power transmission, which is frequency splitting, but no matter which resonant frequency position is, the load can still receive the maximum voltage ;

At η<1, the voltage that the load can receive drops sharply as the coupling coefficient decreases.

Further, since the mutual inductance coefficient M between the transmitting device and the receiving device is:

Among them, μ ₀ is the magnetic permeability of vacuum, n ₁ is the number of turns of the transmitting coil in the sending device, n ₂ is the number of turns of the receiving coil in the receiving device, r ₁ is the radius of the transmitting coil, r ₂ is the radius of the receiving coil, D is the transmission distance. Since the structural dimensions of the transmitting coil and the receiving coil are the same, n ₁ =n ₂ , r ₁ =r ₂ , formula (6) is written as:

And, generally speaking, the magnetic coupling resonant operating frequency is between 1 MHz and 50 MHz, and the loss resistance R ₀ of the transmitting coil under this high frequency condition is:

Among them, ω is the angular frequency of the transmitting device, σ1 is the conductivity _of the transmitting coil, that is, the _first conductivity, and a1 is the wire diameter of the transmitting coil. When it needs to be explained, the loss resistance R ₀ of the transmitting coil is the sum of R ₁ and R ₂ .

When the transmitting device works at the resonant frequency, the voltage received by the load of the receiving device is the maximum value, and the formula (7) and formula (8) can be substituted into

Since the resonant frequency of the transmitting device is equal to the resonant frequency of the receiving device, that is, ω=ω ₁ =ω ₂ , where ω ₁ is the resonant frequency of the transmitting device, recorded as the first resonant angular frequency, and ω ₂ is the resonant frequency of the receiving device , recorded as the second resonant angular frequency. therefore,

It can be seen from this that, when the transmission distance D between the transmitting device and the receiving device is fixed, and the material, coil radius, and resonant operating frequency of the transmitting coil have been fixed, at this time, if the wire diameter of the transmitting coil is divided by the transmission distance When the cube of the radius of the transmitting coil is proportional to the vacuum permeability, the first electrical conductivity, and the negative half power of the first resonant angular frequency, the transmitting device can transmit electric energy to the receiving device. The transmitting device is in a critical coupling state, so that the transmission efficiency is significantly improved.

Embodiment Three

Fig. 4 is a flow chart of a wireless power transmission method provided in another embodiment of the present invention. The execution subject of the wireless power transmission method provided in this embodiment is a receiving device. As shown in Fig. 4, the wireless power transmission method includes:

Step 301, the receiving device receives the electric energy transmitted by the transmitting device through the receiving coil of the receiving device.

Step 302, the receiving device transmits electric energy to the load coil in the receiving device through the receiving coil, wherein the wire diameter of the receiving coil is proportional to the cube of the transmission distance divided by the radius of the receiving coil, and is respectively proportional to the vacuum magnetic permeability , the second conductivity of the receiving coil, and the second resonant angular frequency of the receiving coil are proportional to the negative half of the power, and the distance between the transmitting device and the receiving device is the transmission distance.

Wherein, the second conductivity is determined by the material of the receiving coil, the receiving coil can be copper wire or aluminum wire, the transmission distance, the coil radius of the transmitting coil can be selected according to actual needs, for example, the transmission distance can be selected as 50 cm, in order to limit The volume of the receiving device, the radius of the receiving coil can be selected as 10 cm.

It can be seen that when the transmission distance D between the receiving device and the transmitting device is fixed, and the material, coil radius and resonant operating frequency of the receiving coil of the receiving device are fixed, if the wire diameter of the receiving coil is divided by the transmission distance When it is proportional to the cube of the radius of the receiving coil, and is proportional to the vacuum magnetic permeability, the second electrical conductivity, and the negative half power of the second resonant angular frequency, the receiving device can receive the transmitted signal transmitted by the sending device. When receiving electric energy, the receiving device is in a critical coupling state, so that the transmission efficiency is significantly improved.

Embodiment four

Fig. 5 is a flow chart of a wireless power transmission method provided by another embodiment of the present invention. As shown in Fig. 5, the wireless power transmission method includes:

Step 401, the receiving device receives the electric energy transmitted by the transmitting device through the receiving coil of the receiving device.

Step 402, the receiving device transmits the electric energy to a load coil in the receiving device through the receiving coil.

Wherein, the wire diameter a2 of the receiving coil satisfies the following _formula :

Among them, D is the transmission distance, a ₂ is the wire diameter of the receiving coil, μ ₀ is the vacuum magnetic permeability, ω ₂ is the second resonant angular frequency, σ ₂ is the second electrical conductivity, and r ₂ is the radius of the receiving coil.

According to the above formula, it can be deduced that

In order to facilitate understanding of the technical solution provided in this embodiment, the method for obtaining the above formula is given below.

Specifically, for the receiving device, the receiving device includes a receiving coil and a load coil, which can reflect the load coil to the receiving coil, which is equivalent to adding a reflection impedance to the receiving coil. For the transmitting device, the circuit of the excitation coil can be reflected to the transmitting coil, which is equivalent to adding an induced electromotive force to the transmitting coil. Similarly, as shown in Figure 3, the following formula can be obtained according to the analysis of the simplified circuit diagram in Figure 3:

U _S is the induced electromotive force equivalent to the excitation coil of the transmitter to the transmitter coil, is the amplitude vector of U _S , R ₁ is the sum of the internal resistance of the excitation source of the exciting coil and the first equivalent capacitance of the exciting coil equivalent to the impedance of the transmitting coil, R ₂ is the second loss resistance of the transmitting coil, the second Radiation resistance and the sum of the first loss resistance of the exciting coil and the impedance of the first radiation resistance; M ₂₃ is the mutual inductance coefficient between the transmitting coil and the receiving coil, R ₃ is the third loss resistance of the receiving coil, the third radiation resistance and The sum of the fourth loss resistance of the load coil and the _fourth radiation resistance, R4 is the sum of the load of the load coil of the receiving device and the impedance of the fourth equivalent capacitance equivalent to the receiving coil. L ₂ is the second inductance of the transmitting coil, L ₃ is the third inductance of the receiving coil, C ₂ is the second equivalent capacitance of the transmitting coil, and C ₃ is the third equivalent capacitance of the receiving coil. j is the imaginary unit, I ₁ is the current flowing through the transmitter, is the amplitude vector of I ₁ , I ₂ is the current flowing through the receiving device, is the amplitude vector of I ₂ , ω is the angular frequency of the transmitter or receiver, and the current directions of I ₁ and I ₂ are clockwise in Figure 3.

Optionally, the transmitting device and the receiving device can be designed to have the same size and mechanical structure. In this case, R ₁ +R ₂ =R ₂ +R ₃ , L ₂ =L ₃ , C ₂ =C ₃ , where, Let R ₁ +R ₂ =R ₂ +R ₃ =R, L ₂ =L ₃ =L, C ₂ =C ₃ =C, M ₂₃ =M, and introduce a generalized detuning factor ξ:

in, Q is the quality factor, _ω0 is the resonant frequency, and then according to the formula (1), the following equation can be obtained:

Further, define the coupling factor η, where, Then the voltage received by the receiving device can be obtained according to formula (2):

Wherein, U is the receiving voltage of the electric energy received by the load of the receiving device, is the vector representation of U.

According to the received voltage U, the modulus value of the received voltage can be obtained as:

Among them, |U| is the modulus value of U.

Take the derivative of the modulus |U| of the received voltage, so that It can be obtained that at ξ ₁ =0 and The extreme value of the received voltage modulus is obtained at the place, and the extreme value |U _max | of the received voltage modulus is:

Then, the received voltage of the electric energy received by the load of the receiving device is normalized. The specific normalization method is to divide the received voltage modulus by the extreme value of the received voltage modulus, and the normalized voltage α can be obtained as:

According to the analysis of formula (5), it can be known that ξ=0, that is, when the transmitter works at the resonant frequency ω=ω ₀ :

and in , the voltage received by the load of the receiving device is the maximum value;

At η>1, there will be a phenomenon of frequency splitting, that is, there will be two different resonant frequencies in the process of power transmission, which is frequency splitting, but no matter which resonant frequency position is, the load can still receive the maximum voltage ;

At η<1, the voltage that the load can receive drops sharply as the coupling coefficient decreases.

Further, since the mutual inductance coefficient M between the transmitting device and the receiving device is:

Among them, μ ₀ is the magnetic permeability of vacuum, n ₁ is the number of turns of the transmitting coil in the sending device, n ₂ is the number of turns of the receiving coil in the receiving device, r ₁ is the radius of the transmitting coil, r ₂ is the radius of the receiving coil, D is the transmission distance. Since the structural dimensions of the transmitting coil and the receiving coil are the same, n ₁ =n ₂ , r ₁ =r ₂ , formula (6) is written as:

And, generally speaking, the magnetic coupling resonant operating frequency is between 1 MHz and 50 MHz, and the loss resistance R ₀ ' of the receiving coil under this high frequency condition is:

Among them, ω is the angular frequency of the receiving device, _σ2 is the conductivity of the transmitting coil, that is, the _second conductivity, and a2 is the wire diameter of the receiving coil. It should be noted that the loss resistance R ₀ ′ of the receiving coil is the sum of R ₃ and R ₄ .

When the receiving device works at the resonant frequency, that is, the voltage received by the load of the receiving device is the maximum value, and formula (7 ^* ) and formula (8 ^* ) can be substituted into

Since the resonant frequency of the receiving device is equal to the resonant frequency of the transmitting device, that is, ω=ω ₁ =ω ₂ , where ω ₂ is the resonant frequency of the receiving device, recorded as the second resonant angular frequency, and ω ₁ is the resonant frequency of the transmitting device , denoted as the first resonant angular frequency. therefore,

It can be seen that when the transmission distance D between the transmitting device and the receiving device is fixed, and the material, coil radius and resonant operating frequency of the receiving coil have been fixed, if the wire diameter of the receiving coil is divided by the transmission distance by the receiving coil is proportional to the cube of the radius, and is proportional to the vacuum permeability, the second electrical conductivity, and the negative half power of the second resonant angular frequency respectively, when the receiving device receives the electric energy transmitted by the transmitting device, the receiving device is at The critical coupling state makes the transmission efficiency significantly improved.

Embodiment five

This embodiment provides a wireless power transmission device, which is used to implement the wireless power transmission method in Embodiment 1 and Embodiment 2. FIG. 6 is a schematic circuit diagram of the wireless power transmission device provided in this embodiment. As shown in FIG. 6, the The wireless power transmitting device includes: an exciting coil 11 for transferring the energy corresponding to the acquired alternating current to the transmitting coil, and a transmitting coil 12 for transmitting electric energy generated according to the above energy to the wireless power receiving device.

Wherein, the wire diameter of transmitting coil 12 is directly proportional to the cube of the transmission distance divided by the radius of the transmitting coil, and is respectively proportional to the vacuum magnetic permeability, the first electrical conductivity of the transmitting coil, and the minus two of the first resonant angular frequency of the transmitting coil. It is proportional to the power of one-third; the distance between the transmitting device and the receiving device is the transmission distance.

Wherein, the excitation coil 11 includes an excitation source and a single-turn coil connected in series, and the transmitting coil 12 is a multi-turn coil. The number of turns of the transmitting coil 12 can be determined according to the resonant frequency of the transmitting device when it is working.

When the transmission distance D between the transmitting device and the receiving device is fixed, and the material, coil radius and resonant operating frequency of the transmitting coil 12 have been fixed, if the wire diameter of the transmitting coil 12 is divided by the transmission distance by the transmission distance of the transmitting coil 12 When the cube of the radius is proportional to the vacuum magnetic permeability, the first electrical conductivity, and the negative half power of the first resonant angular frequency, the transmitting device can be in the The critical coupling state makes the transmission efficiency significantly improved.

Embodiment six

This embodiment is a further supplementary description to the above embodiment, wherein the wire diameter a1 of the transmitting coil ₁₂ satisfies the following formula:

Among them, D is the transmission distance, a ₁ is the wire diameter of the transmitting coil, μ ₀ is the vacuum magnetic permeability, ω ₁ is the first resonant angular frequency, σ ₁ is the first electrical conductivity, and r ₁ is the radius of the transmitting coil.

In addition, the internal resistance and capacitance of the excitation coil 11 can be equivalent to obtain the equivalent circuit of the excitation coil 11, as shown in Figure 6, the equivalent circuit includes: the first radiation resistance R _rad1 and the excitation coil connected in series 11 The first loss resistance R _p1 , the internal resistance R _s of the excitation source, the first equivalent capacitance C ₁ , and the first inductance L ₁ due to skin effect and other factors.

Similarly, the equivalent circuit of the transmitting coil 12 can also be obtained. As shown in FIG. 6, the equivalent circuit of the transmitting coil 12 includes: the second radiation resistance R _rad2 connected in series, The second loss resistor R _p2 , the second equivalent capacitor C ₂ and the second inductance L ₂ .

Further, the equivalent circuit of the exciting coil 11 can be reflected to the transmitting coil 12 to obtain the equivalent circuit of the transmitting device, as shown in Figure 3, wherein the equivalent circuit of the transmitting device includes: The resistance R _s and the first equivalent capacitance C ₁ of the exciting coil 11 are equivalent to the sum R ₁ of the impedance of the transmitting coil 12, the first loss resistance R _p1 of the exciting coil 11 and the first radiation resistance R _rad1 and the impedance of the transmitting coil 12 The second loss resistance R _p2 and the second radiation resistance R _rad2 are equivalent to the sum R ₂ of the impedance of the transmitting coil 12 , the second inductance L ₂ of the transmitting coil 12 , and the second equivalent capacitance C ₂ of the transmitting coil 12 .

Specifically, the method for obtaining the wire diameter of the transmitting coil 12 may refer to the detailed description of the second embodiment, and details are not repeated here.

When the transmission distance D between the transmitting device and the receiving device is fixed, and the material, coil radius and resonant operating frequency of the transmitting coil 11 are fixed, if the wire diameter of the transmitting coil is equal to the transmission distance divided by the radius of the transmitting coil is proportional to the cube, and is proportional to the vacuum permeability, the first electrical conductivity, and the negative half power of the first resonant angular frequency respectively, then the transmitting device can be in critical coupling when the transmitting device transmits electric energy to the receiving device state, so that the transmission efficiency is significantly improved.

Embodiment seven

This embodiment provides a wireless power receiving device, which is used to implement the wireless power transmission method in Embodiment 3 and Embodiment 4. FIG. 7 is a schematic circuit diagram of the wireless power receiving device provided in this embodiment, as shown in FIG. 7 , The wireless power receiving device includes: a receiving coil 21 for receiving the power transmitted by the transmitting device, and a load coil 22 for receiving the power transmitted by the receiving coil 21 .

Specifically, the receiving coil 21 is a multi-turn coil, and the load coil 22 includes a load and a single-turn coil connected in series.

Wherein, the wire diameter of the receiving coil 21 is proportional to the cube of the transmission distance divided by the radius of the receiving coil, and is proportional to the negative half power of the second vacuum permeability, the second electrical conductivity, and the second resonant angular frequency, respectively. In direct proportion, the distance between the transmitting device and the receiving device is the transmission distance.

Specifically, the receiving coil 21 is a multi-turn coil, and the load coil 22 includes a load and a single-turn coil connected in series.

Wherein, the second conductivity is determined by the material of the receiving coil 21, the receiving coil 21 can adopt copper wire or aluminum wire, the transmission distance, the radius of the receiving coil 21 can be selected according to actual needs, for example, the transmission distance can be selected as 50 cm, In order to limit the volume of the receiving device, the radius of the receiving coil 21 can be selected as 10 cm.

It can be seen that when the transmission distance D between the receiving device and the transmitting device is fixed, and the material, coil radius and resonant operating frequency of the receiving coil 21 of the receiving device are fixed, if the wire diameter of the receiving coil 21 is the same as that of the transmission When the distance is proportional to the cube of the radius of the receiving coil 21, and is proportional to the negative half power of the vacuum permeability, the second electrical conductivity, and the second resonant angular frequency respectively, then the receiving device can be made to receive and send When the electric energy transmitted by the device is received, the receiving device is in a critical coupling state, so that the transmission efficiency is significantly improved.

Embodiment Eight

This embodiment is a further explanation of the above embodiment, wherein the wire diameter a2 of the receiving coil ₂₁ satisfies the following formula:

Among them, D is the transmission distance, a ₂ is the wire diameter of the receiving coil, μ ₀ is the vacuum magnetic permeability, ω ₂ is the second resonant angular frequency, σ ₂ is the second electrical conductivity, and r ₂ is the radius of the receiving coil.

In addition, the internal resistance and capacitance of the receiving coil 21 can be equivalent to obtain the equivalent circuit of the receiving coil 21, as shown in Figure 7, the equivalent circuit includes: the third radiation resistor R _rad3 and the receiving coil connected in series 21 The third loss resistance R _p3 , the third equivalent capacitance C ₃ , and the third inductance L ₃ generated due to skin effect and other factors.

Similarly, the load coil 22 can also obtain an equivalent circuit, as shown in Figure 7, the equivalent circuit of the load coil 22 includes: the fourth radiation resistor R _rad4 connected in series and the load coil 22 due to factors such as skin effect The fourth loss resistor R _p4 , the fourth inductor L ₄ , the fourth equivalent capacitor C ₄ and the load R _L .

Further, the equivalent circuit of the load coil 22 can be reflected to the receiving coil 21 to obtain the equivalent circuit of the receiving device, as shown in FIG. 3 , wherein the equivalent circuit of the receiving device includes: the third radiation resistance of the receiving coil 21 R _rad3 and the third loss resistance R _p3 and the fourth radiation resistance R _rad4 of the load coil 22 and the impedance sum of the fourth loss resistance Rp4 R ₃ , the load R _L of the load coil 22 and the fourth capacitance C ₄ are equivalent to the receiver The sum R ₄ of the impedance of the coil 21 , the third equivalent capacitance C ₃ of the receiving coil 21 , and the third inductance L ₃ of the receiving coil 21 .

Specifically, the method for obtaining the wire diameter of the receiving coil 21 may refer to the detailed description of Embodiment 4, and details are not repeated here.

When the transmission distance D between the transmitting device and the receiving device is fixed, and the material, coil radius and resonant operating frequency of the receiving coil have been fixed, if the wire diameter of the receiving coil is the cube of the transmission distance divided by the radius of the receiving coil When it is directly proportional to the vacuum magnetic permeability, the second electrical conductivity, and the negative half power of the second resonant angular frequency, the receiving device can be in a critical coupling state when the receiving device receives the electric energy transmitted by the transmitting device , so that the transmission efficiency is significantly improved.

Embodiment nine

This embodiment provides a power transmission system. As shown in FIG. 3, the wireless power transmission system includes the power transmitting device 1 and the wireless power receiving device 2 provided in the above embodiment, wherein the wire diameter of the transmitting coil and the diameter of the receiving coil The wire diameters are equal, the first resonant angular frequency is equal to the second resonant angular frequency, the first conductivity is equal to the second conductivity, and the radius of the transmitting coil is equal to the radius of the receiving coil. That is, the transmitting device and the receiving device can be designed to have the same size and mechanical structure. Also, the transmitting coil and the receiving coil are helical coils and coaxially placed.

It can be seen that when the transmission distance D between the transmitting device and the receiving device is fixed, and the material, coil radius and resonant operating frequency of the receiving coil have been fixed, if the wire diameter of the receiving coil is divided by the transmission distance by the receiving coil is proportional to the cube of the radius, and is proportional to the vacuum magnetic permeability, the second electrical conductivity, and the negative half power of the second resonant angular frequency respectively, when the receiving device receives the electric energy transmitted by the transmitting device, the entire electric energy The transmission system is in a critically coupled state, so that the transmission efficiency is significantly improved.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, passengers of ordinary skill in the art should understand that: it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (10)

1. A wireless power transmission method, comprising:

the transmitting device transmits the energy corresponding to the acquired alternating current to a transmitting coil in the transmitting device through an exciting coil in the transmitting device;

the transmitting device transmits electric energy to the receiving device through the transmitting coil, and the electric energy is generated by the transmitting coil according to the energy;

wherein, under the condition that the transmission distance between the transmitting device and the receiving device is fixed, and the material, the coil radius and the resonance working frequency of the transmitting coil are fixed, the linear diameter of the transmitting coil is in direct proportion to the cube of the transmission distance divided by the radius of the transmitting coil, and is in direct proportion to the vacuum magnetic permeability, the first electric conductivity of the transmitting coil and the minus half power of the first resonance angular frequency of the operation of the transmitting coil respectively;

the distance between the transmitting device and the receiving device is a transmission distance.

2. The wireless power transmission method according to claim 1, wherein a wire diameter a of the transmitting coil₁The following formula is satisfied:

wherein D is a transmission distance, mu₀Is a vacuum magnetic permeability, omega₁At a first resonant angular frequency, σ₁Is a first conductivity, r₁Is the radius of the transmit coil.

3. A wireless power transmission method, comprising:

the receiving device receives the electric energy transmitted by the transmitting device through a receiving coil of the receiving device;

the receiving device transmits the electric energy to a load coil in the receiving device through the receiving coil;

wherein, under the condition that the transmission distance between the receiving device and the transmitting device is fixed, and the material, the coil radius and the resonance working frequency of a receiving coil of the receiving device are fixed, the linear diameter of the receiving coil is in direct proportion to the cube of the transmission distance divided by the radius of the receiving coil, and is in direct proportion to the vacuum magnetic permeability, the second electric conductivity of the receiving coil and the negative half power of the second resonance angular frequency of the receiving coil;

the distance between the transmitting device and the receiving device is a transmission distance.

4. The wireless power transmission method according to claim 3, wherein a wire diameter a of the receiving coil₂The following formula is satisfied:

wherein D is a transmission distance, a₂Which is the wire diameter of the receiving coil,is the second vacuum permeability, ω₂At a second resonance angular frequency, σ₂Is a second conductivity, r₂Is the radius of the receive coil.

5. A wireless power transmitting device, comprising: an excitation coil for transmitting energy corresponding to the acquired alternating current to a transmitting coil, and the transmitting coil for transmitting electric energy generated according to the energy to a wireless electric energy receiving device;

wherein, under the condition that the transmission distance between the transmitting device and the receiving device is fixed, and the material, the coil radius and the resonance working frequency of the transmitting coil are fixed, the linear diameter of the transmitting coil is in direct proportion to the cube of the transmission distance divided by the radius of the transmitting coil, and is in direct proportion to the vacuum magnetic permeability, the first electric conductivity of the transmitting coil and the minus half power of the first resonance angular frequency of the operation of the transmitting coil respectively;

the distance between the transmitting device and the receiving device is a transmission distance.

6. The apparatus of claim 5, wherein the excitation coil comprises an excitation source and a single turn coil connected in series, and the transmission coil is a multi-turn coil.

7. The wireless power transmission apparatus of claim 5, wherein the transmission coil is ofWire diameter a₁The following formula is satisfied:

wherein D is a transmission distance, a₁Is the wire diameter of the transmitting coil, mu₀Is a vacuum magnetic permeability, omega₁At a first resonant angular frequency, σ₁Is a first conductivity, r₁Is the radius of the transmit coil.

8. A wireless power receiving device, comprising:

the receiving coil is used for receiving the electric energy transmitted by the transmitting device, and the load coil is used for receiving the electric energy transmitted by the receiving coil;

wherein, under the condition that the transmission distance between the receiving device and the transmitting device is fixed, and the material, the coil radius and the resonance working frequency of a receiving coil of the receiving device are fixed, the linear diameter of the receiving coil is in direct proportion to the cube of the transmission distance divided by the radius of the transmitting coil, and is in direct proportion to the second vacuum magnetic permeability, the second electric conductivity and the negative half power of the second resonance angular frequency respectively;

the distance between the transmitting device and the receiving device is a transmission distance.

9. The device of claim 8, wherein the wire diameter a of the receiving coil is larger than the wire diameter of the receiving coil₂The following formula is satisfied:

wherein D is a transmission distance, a₂Is the wire diameter of the receiving coil, mu₀Is the second vacuum permeability, ω₂At a second resonance angular frequency, σ₂Is a second conductivity, r₂Is the radius of the receive coil.

10. A wireless power transfer system comprising a wireless power transmitting device as claimed in any one of claims 5 to 7 and a wireless power receiving device as claimed in any one of claims 8 to 9, wherein the wire diameter of the transmitting coil and the wire diameter of the receiving coil are equal, the first resonant angular frequency and the second resonant angular frequency are equal, the first conductivity and the second conductivity are equal, and the radius of the transmitting coil and the radius of the receiving coil are equal.