CN114530948B - Wireless energy transmission system and method utilizing second harmonic positioning - Google Patents

Abstract

The invention discloses a wireless energy transmission system and method using second harmonic positioning. The transmission system includes a radio frequency energy transmitting end and a radio frequency energy receiving end. The number of radio frequency energy transmitting ends is at least three. Each of the radio frequency energy transmitting ends The transmitting end includes an energy transmitting device, a second harmonic receiving antenna, and a signal processing module. The RF energy receiving end includes an energy receiving rectenna and a second harmonic radiation antenna. The energy receiving rectenna is used to receive the frequency modulated continuous wave signal from the energy transmitting end. The energy is converted into electrical energy, during which the second harmonic is generated through the nonlinear device; the second harmonic radiation antenna is used to radiate the second harmonic generated by the energy receiving rectenna. The present invention can not only increase the distance of wireless energy transmission, but also realize the alignment of the radio frequency energy transmitting end antenna and the energy receiving end antenna without consuming the power of the energy receiving end, thereby improving the transmission efficiency of the radio frequency wireless energy transmission system.

Description

A wireless energy transmission system and method using second harmonic positioning

Technical field

The invention belongs to the field of radio frequency wireless energy technology and relates to a wireless energy transmission system and method utilizing second harmonic positioning.

Background technique

Wireless energy transmission refers to the way in which an energy source transmits energy to an energy receiving end without contact. Wireless energy transmission technologies mainly include electromagnetic induction coupling, magnetic resonance coupling, laser wireless energy transmission and radio frequency wireless energy transmission. Among them, electromagnetic induction coupling and magnetic resonance coupling are near-field wireless energy transmission methods. Their advantage is high transmission efficiency, but their disadvantage is short transmission distance. Electromagnetic induction coupling is currently the most mature wireless energy transmission technology and has been widely used in various digital products and household appliances. However, electromagnetic induction coupling can only be used for short-range (millimeter to centimeter level) energy transmission. Laser wireless energy transmission and radio frequency wireless energy transmission are far-field energy transmission methods. However, laser wireless energy transmission has weak anti-interference. When there are obstacles in the transmission path, it will seriously affect the energy transmission efficiency, and the application of laser is dangerous. sex. In comparison, radio frequency wireless energy transmission is less affected by the environment and is suitable for long-distance energy transmission.

Radio frequency wireless energy transmission is a wireless transmission method that transmits energy by radiating radio frequency electromagnetic waves. The RF energy transmitter converts DC power into RF energy. The RF energy realizes space energy radiation through the antenna. The RF energy receiver collects the energy radiated from space and converts it into easy-to-use DC through the antenna and rectifier circuit. The converted DC power is It can be powered directly to low-power devices or stored in a battery. Compared with laser energy transmission, radio frequency wireless energy transmission has a certain anti-interference ability due to the penetrability of electromagnetic waves; compared with near-field wireless energy transmission, radio frequency wireless energy transmission has potential for long-distance transmission. Long-distance transmission capability, but radio frequency wireless energy transmission method has the problem of low energy transmission efficiency. The main factors that affect the efficiency of radio frequency wireless energy transmission include path attenuation when radio frequency electromagnetic waves propagate in space; the energy conversion efficiency of the energy conversion circuits at the radio frequency energy transmitter and radio frequency energy receiver; and the misalignment of the radio frequency energy transmitting antenna with the radio frequency energy receiving antenna. The path attenuation of radio frequency electromagnetic waves propagating in space is inevitable; for the problem of low energy conversion efficiency of the energy conversion circuits at the radio frequency energy transmitting end and radio frequency energy receiving end, there has been research on more efficient conversion circuits.

As for the alignment problem of energy transmitting antennas and RF energy receiving antennas, current solutions are mostly based on the method of using beam forming at the energy transmitting end, that is, using a phased array antenna at the energy transmitting end to form a beam directed to the energy receiving end antenna. However, this method either requires the energy receiving end to send a signal first to allow the energy transmitting end to determine its position, which requires additional power consumption for low-power devices; or the energy transmitting end determines the position of the energy receiving end through beam scanning. , but the collected energy power value needs to be measured at the energy receiving end and fed back to the energy transmitting end. This not only requires a complex scanning algorithm, but also not only requires the integration of a signal processing module inside the energy receiving end, but also adds unnecessary energy loss.

Contents of the invention

In order to solve the above problems, the present invention provides a wireless energy transmission system that utilizes second harmonic positioning, which can not only increase the distance of wireless energy transmission, but also realize the radio frequency energy transmitting end antenna and the radio frequency energy transmitting end antenna without consuming the energy receiving end. The alignment of the energy receiving end antenna further improves the transmission efficiency of the radio frequency wireless energy transmission system and solves the problems existing in the existing technology.

Another object of the present invention is to provide a wireless energy transmission method using second harmonic positioning.

The technical solution adopted by the present invention is a wireless energy transmission system utilizing second harmonic positioning, including

Radio frequency energy transmitting ends. The number of the radio frequency energy transmitting ends is at least three and non-coplanar. Each of the radio frequency energy transmitting ends includes

An energy transmitting device for transmitting frequency modulated continuous wave signals; and

a second harmonic receiving antenna for receiving the second harmonic signal from the energy receiving end; and

The signal processing module is used to perform signal processing on the received second harmonic signal, obtain the position information of the energy receiving end, and feed back the position information of the energy receiving end to the energy transmitting device. The energy transmitting device adjusts the beam center to align with the radio frequency in real time. energy receiving end;

Radio frequency energy receiving end, the radio frequency energy receiving end includes

The energy receiving rectenna is used to receive the energy of the frequency modulated continuous wave signal from the energy transmitting end and convert it into electrical energy. In the process, the second harmonic is generated through the nonlinear device; and

The second harmonic radiation antenna is used to radiate the second harmonic generated by the energy receiving rectenna.

Further, the radio frequency energy transmitting end also includes

Signal source, used to generate original frequency modulated continuous wave signals to realize the conversion of electrical energy into radio frequency energy;

A power amplifier is used to amplify the power of the generated signal and send it to the energy transmitting device.

Further, the energy receiving rectenna includes

Energy receiving antenna, used to receive frequency modulated continuous wave signals emitted by the energy transmitting device;

The rectifier circuit is used to convert radio frequency energy into electrical energy, and at the same time radiate the generated second harmonic signal outward through the second harmonic radiation antenna.

Further, the frequency modulated continuous wave signals emitted by the three radio frequency energy transmitting ends are respectively recorded as S ₁ , S ₂ and S ₃ . The signals S ₁ , S ₂ and S ₃ respectively pass through the second harmonic generated by the radio frequency energy receiving end. The wave signals are recorded as S _r1 , S _r2 and S _r3 respectively. Based on the second harmonic signals corresponding to the three sets of radio frequency energy transmitting ends at different positions, the distance between the corresponding radio frequency energy transmitting end and the radio frequency energy receiving end is calculated, which is recorded as R ₁ , R ₂ , R ₃ , obtain the intersection point of the three circles with the three RF energy transmitting ends as the center and R ₁ , R ₂ , and R ₃ as the radii, that is, the location of the RF energy receiving end.

Further, the distance R between the radio frequency energy transmitting end and the radio frequency energy receiving end is determined according to the following formula:

Among them, c represents the propagation speed of electromagnetic waves, T _s is the frequency sweep period, that is, the period of the frequency modulated continuous wave signal; B is the bandwidth of the frequency modulated continuous wave signal, f _b represents the frequency of the difference frequency signal, and τ is the transmission delay.

Further, the frequency modulated continuous wave signals transmitted by the three radio frequency energy transmitting ends are non-coherent.

A wireless energy transmission method using second harmonic positioning, using the above-mentioned wireless energy transmission system using second harmonic positioning, specifically following the following steps:

Step S1, the energy transmitting devices of at least three radio frequency energy transmitting ends transmit non-coherent frequency modulated continuous wave signals. The transmitted frequency modulated continuous wave signals propagate in space and are received by the energy receiving rectenna of the radio frequency energy receiving end and converted into electrical energy;

Step S2, in the process of receiving the frequency modulated continuous wave signal by the energy receiving rectenna, the nonlinear device generates the second harmonic, which is radiated through the second harmonic radiation antenna;

Step S3: The second harmonic receiving antenna at the radio frequency energy transmitting end receives the second harmonic signal from the energy receiving end;

Step S4: The radio frequency energy transmitting end processes the received second harmonic signal through the signal processing module to obtain the location information of the energy receiving end;

Step S5: The signal processing module feeds back the position information of the energy receiving end to the energy transmitting device, and the energy transmitting device adjusts the beam center to align with the radio frequency energy receiving end in real time.

Further, in the steps S2 and S3, the second harmonic signal S ₀ emitted by the second harmonic radiation antenna at the radio frequency energy receiving end is expressed as: Where ρ ₀ is the amplitude of the signal emitted by the second harmonic radiation antenna, ω ₀ represents the input signal frequency, ω ₀ =2πf ₀ , A represents the intermediate parameter, A = 2πB/T _s , T _s is the frequency sweep period, frequency sweep Period refers to the period of FM continuous wave signal; t is time;

The second harmonic signal S _H received by the second harmonic receiving antenna at the radio frequency energy transmitting end is expressed as: S _H =ρ ₁ cos(2ω ₀ (t-τ)+A(t-τ) ² ), where ρ ₁ Represents the amplitude of the signal received by the second harmonic receiving antenna, and τ is the transmission delay;

The second harmonic signal _Sk generated by the circuit at the energy transmitting end is expressed as: _Sk =ρ ₂ cos(2ω ₀ t+At ² ), where ρ ₂ represents the second harmonic signal generated by the circuit at the energy transmitting end. amplitude;

After mixing the signal _Sk and _SH we get:

Among them, the first term cos[(4ω ₀ -2Aτ)t+2At ² +(Aτ ² -2ω ₀ )t] is filtered out, and the second term cos[2Atτ+(2ω ₀ τ-Aτ ² )]) represents the difference frequency signal, and the phase derivation of the difference frequency signal is used to obtain its frequency, expressed as/> Since τ=2R/c, where c represents the propagation speed of electromagnetic waves, therefore through the formula/> The distance R between the radio frequency energy receiving end and the radio frequency energy transmitting end can be determined.

Further, in step S4, according to the positions of the three radio frequency energy transmitting ends in the spatial coordinate system, the coordinates of the first radio frequency energy transmitting end are obtained as (x ₁ , y ₁ , z ₁ ), and the coordinates of the second radio frequency energy transmitting end are respectively obtained. is (x ₂ , y ₂ , z ₂ ), the coordinates of the radio frequency energy transmitting end are (x ₃ , y ₃ , z ₃ ); assuming that the coordinates of the radio frequency energy receiving end are (x, y, z), the radio frequency energy transmitting end 1. The distances between RF energy transmitting end 2 and RF energy transmitting end 3 and the RF energy receiving end are respectively recorded as R ₁ , R ₂ and R ₃ . Since the three RF energy transmitting ends are not in the same plane, the three RF energy transmitting ends are The intersection point of three circles with R ₁ , R ₂ , and R ₃ as the center and radii R 1 , R 2 , and R 3 is the location coordinate of the radio frequency energy receiving end.

Further, the coordinates of the radio frequency energy receiving end are (x, y, z) and are solved by the following set of equations:

The present invention uses three radio frequency energy transmitting devices to transmit frequency modulated continuous wave signals of the same frequency. In order to reduce the loss of energy propagation in space and avoid additional energy overhead at the energy receiving end, the present invention uses frequency modulated continuous wave radar signals in nonlinear The device will produce harmonic signal characteristics, and the second harmonic signal generated at the energy receiving end will be radiated through the antenna. Then the three energy receiving devices will process the received second harmonic signal to calculate The position information of the energy receiving end is then fed back to the transmitting antenna of the energy transmitting end. The transmitting antenna adjusts its beam direction to achieve the alignment of the radio frequency energy transmitting antenna and the energy receiving antenna.

The beneficial effects of the present invention are:

1. The radio frequency wireless transmission system proposed by the present invention has the advantages of long energy transmission distance and anti-interference. At the same time, it can also adjust the antenna beam direction of the radio frequency energy transmitting end in real time to realize the alignment of the transmitting end antenna and the energy receiving end antenna, so that it can Long-distance wireless energy transmission for moving devices.

2. The present invention uses frequency modulated continuous wave signals to achieve long-distance and high-efficiency radio frequency wireless energy transmission. In order to achieve the alignment of the transmitting end antenna and the energy receiving end antenna, the present invention utilizes the harmonics generated by radio frequency electromagnetic waves through nonlinear devices. This physical characteristic obtains the position information of the energy receiving end by recycling the second harmonic energy. Different from other radio frequency wireless energy transmission systems, the present invention does not need to consume the power of the energy receiving end to complete the alignment of the energy transmitting end and the energy receiving end antenna, and performs long-distance energy transmission for moving equipment; for example, it can be used for smart devices in logistics warehouses. The handling and sorting robots are charged while working, which eliminates the need for the machine to return to a fixed location to rest and recharge when the battery is low, which can improve the working efficiency of the machine. Compared with other methods, the method proposed by the present invention is more suitable for charging movable, low-power consumption devices, has a longer transmission distance, and has higher transmission efficiency.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting creative efforts.

Figure 1 is a structural diagram of a wireless energy transmission system using second harmonic positioning according to an embodiment of the present invention.

Figure 2 is an energy transfer model diagram between the energy transmitting end and the energy receiving end according to the embodiment of the present invention.

Figure 3 is a flow chart of the rectifier circuit system according to the embodiment of the present invention.

Figure 4 is a schematic diagram of a rectifier circuit according to an embodiment of the present invention.

Figure 5 is a schematic diagram of the positioning algorithm according to the embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

Example 1,

A wireless energy transmission system using second harmonic positioning, as shown in Figure 1, includes a radio frequency energy transmitter and a radio frequency energy receiver.

The radio frequency energy transmitting end includes three energy transmitting devices. Each energy transmitting device includes a signal source, a power amplifier, an energy transmitting antenna, a second harmonic receiving antenna and a signal processing module. The three energy transmitting devices are installed in different locations. On the plane, it is convenient to obtain the position information of the energy receiving end later.

Signal source is used to generate original frequency modulated continuous wave signals to realize the conversion of electrical energy into radio frequency energy.

Power amplifier is used to amplify the power of the generated signal.

The energy transmitting antenna is used to transmit the amplified frequency modulated continuous wave signal.

The second harmonic receiving antenna is used to receive the second harmonic signal from the energy receiving end.

The signal processing module is used to perform signal processing on the received second harmonic signal, obtain the position information of the energy receiving end, and feed back the position information of the energy receiving end to the energy transmitting device. The energy transmitting device adjusts the beam center to align with the radio frequency in real time. energy receiving end;

The energy receiving end is a radio frequency energy receiving device. The radio frequency energy receiving device includes an energy receiving rectenna and a second harmonic radiation antenna. The energy receiving rectenna includes an energy receiving antenna and a rectifier circuit. The energy receiving antenna is used to capture the energy of the frequency modulated continuous wave signal from the energy transmitter. The rectifier circuit converts the received radio frequency energy into electrical energy, during which process it passes through nonlinear devices. The second harmonic is generated, and the generated second harmonic is emitted through the second harmonic radiation antenna.

The energy transfer model between the radio frequency energy transmitting end and the radio frequency energy receiving end is shown in Figure 2. The three radio frequency energy transmitting ends are marked as radio frequency energy transmitting end one, radio frequency energy transmitting end two and radio frequency energy transmitting end three. Each radio frequency energy transmitter contains two modules: radio frequency energy transmission and second harmonic reception. The transmission signals of the three radio frequency energy transmitting ends are marked as S ₁ , S ₂ and S ₃ respectively, and the second harmonic signals generated by the energy transmitting signal passing through the energy receiving end circuit are marked as S _r1 , S _r2 and S _r3 respectively.

The purpose of using three energy transmitting ends in the embodiment of the present invention is to obtain three sets of second harmonic signals at different positions, and calculate the distances between each of them and the energy receiving end, which are recorded as R ₁ , R ₂ , and R ₃ , and are used as positioning signals through Subsequent signal processing calculates the position information of the energy receiving end, and uses the position information to adjust the direction of the antenna's beam center to achieve alignment from the energy transmitting end to the energy receiving end antenna, thereby achieving maximum power transmission efficiency.

Example 2,

A wireless energy transmission method using second harmonic positioning, including the following steps:

Step S1, the energy transmitting devices of at least three radio frequency energy transmitting ends transmit non-coherent frequency modulated continuous wave signals; the energy transmitting end generates frequency modulated continuous wave signals through the signal source, and the generated frequency modulated continuous wave signals realize the transformation from electrical energy to radio frequency Transformation of energy. Since the power of the FM continuous wave signal generated by the signal source is generally low, a power amplifier is used after the signal source to amplify the RF signal. The radio frequency signal amplified by the power amplifier is transmitted through the energy transmitting antenna at the radio frequency energy transmitting end. The transmitted FM continuous wave signal propagates in space and will eventually be captured by the energy receiving antenna at the radio frequency energy receiving end. After the radio frequency energy receiving end receives the signal through the energy receiving antenna, it completes the conversion of radio frequency energy and electrical energy through the rectifier circuit.

Step S2: During the process of receiving the FM continuous wave signal by the energy receiving rectenna, the nonlinear device of the energy receiving rectenna generates a second harmonic, and the generated second harmonic signal is radiated outward through the second harmonic radiation antenna. ;

The system flow of the rectifier circuit is shown in Figure 3; the rectifier circuit includes a low-pass filter, a matching circuit, a rectifier diode, a straight-through filter and a load. The signal first passes through the low-pass filter, then passes through the matching circuit and rectifier circuit, and finally passes through The pass-through filter is delivered to the load to complete wireless energy transmission; the rectifier circuit is used to convert RF energy into electrical energy.

First, the input low-pass filter filters the FM continuous wave signal, and then the matching circuit realizes the matching between the input low-pass filter and the rectifier diode. The rectifier diode rectifies the RF signal into DC power, and finally the rectified The DC voltage is smoothed and filtered to obtain a stable DC voltage.

The rectifier diode uses a Schottky barrier diode. The Schottky barrier diode is the core of the rectifier circuit and also plays a decisive role in the rectification efficiency of the rectifier circuit. The Schottky diode is a nonlinear device. The received FM continuous wave signal will generate harmonic components through the nonlinear device. The harmonic components are composed of integer multiples of the signal frequency. The relationship between the current and voltage through the Schottky diode can be expressed as Where q is the charge, k represents Boltzmann's constant, T is the temperature, n represents the ideality factor, _IS represents the saturation current, I(V) represents the voltage through the diode, and v represents the conduction voltage drop of the diode.

The voltage of the input signal of the rectifier (rectifier circuit) V = V _s cos (ω ₀ t), where _VS is the amplitude of the signal (ie, frequency modulated continuous wave), ω ₀ represents the input signal frequency, and t represents time.

The output response of the nonlinear diode rectifier can be described by Taylor series, where the sinusoidal input signal voltage can be expressed as V ₀ ＝x ₀ +x ₁ V _s cos(ω ₀ t)+x ₂ [V _s cos(ω ₀ t) ] ² +x ₃ [V _s cos(ω ₀ t)] ³ +…, where x ₀ , x ₁ , x ₂ ,… represent Taylor expansion coefficients.

because so,

V ₀ represents the sinusoidal input signal voltage.

Therefore, the output voltage contains the DC rectified output and the AC signals ω ₀ , 2ω ₀ , 3ω ₀ .... The second harmonic of the rectifier can be expressed as At the same time, the second harmonic is also the harmonic component with the highest power value in the harmonic response. The embodiment of the present invention utilizes this physical characteristic to radiate the generated second harmonic at the radio frequency energy receiving end through the second harmonic radiation antenna as a positioning signal.

The schematic diagram of the rectifier circuit with second harmonic recovery is shown in Figure 4, where the radio frequency input in Figure 4 is the energy receiving antenna in Figure 1, and the matching and filtering circuit, rectifier diode and pass-through filter correspond to the rectifier circuit in Figure 1; Among them, the matching and filtering circuit realizes the matching between the input low-pass filter and the rectifier diode, and also completes the low-pass filtering function. The matching circuit and filter are important aspects that affect the rectification efficiency. Low-pass filters are used to filter noise and clutter. On a radio frequency transmission line, the ratio of voltage to current is called characteristic impedance; at both ends of the load, the ratio of voltage to current is equal to the load impedance. When the load impedance is different from the characteristic impedance, the voltage and current on the transmission line are discontinuous with the voltage and current on the load. At this time, a part of the reflected wave will be generated. When the load impedance is equal to the characteristic impedance, no reflection will occur and the load absorbs all energy. That is to say, when the circuit does not match, the RF signal does not effectively enter the diode and is lost by reflection, or causes power instability. Therefore, a matching circuit is required to achieve maximum energy transmission. Capacitors C1 and C2 are used to isolate DC signals, and inductor L is used to isolate RF signals. The two diodes realize double voltage rectification, and the rectified DC signal is transmitted to the load through the inductor L. The second harmonic generated by the diode passes through the capacitor C2 and is finally emitted through the second harmonic radiation antenna.

Step S3, the energy transmitting devices of the three radio frequency energy transmitting ends receive the second harmonic signal generated from the energy receiving end through the second harmonic receiving antenna; the radar has a certain degree of anti-interference, because the energy transmitted by the three energy transmitting ends The signals are non-coherent. The initial phase of the signal emitted by each radar must be different. In this way, when the echo signal is received, only its own echo is coherent, so it can distinguish itself through matching filtering. The second harmonic generated by the transmitted signal.

Step S4: The radio frequency energy transmitting end processes the received FM continuous wave signal, and then calculates its position information. Assume that the frequency modulated continuous wave signal transmitted in the frequency range [f ₀ , f ₀ +B] is Among them, ρ ₀ is the amplitude of the signal transmitted by the second harmonic transmitting antenna, f ₀ is the starting frequency of the frequency modulated continuous wave signal, B is the frequency modulated continuous wave signal bandwidth, ω ₀ =2πf ₀ , A represents the intermediate parameter, A = 2πB / _Ts .

The expression of the second harmonic signal received by the second harmonic receiving antenna at the radio frequency energy transmitting end is S _H =ρ ₁ cos(2ω ₀ (t-τ)+A(t-τ) ² ), where A = 2πB/ T _s , ρ ₁ represents the amplitude of the signal received by the second harmonic receiving antenna, and T _s is the frequency sweep period. The frequency sweep period refers to the period of the FM continuous wave signal, which is set when designing the transmit signal parameters. are known parameters; t is time and τ is transmission delay. The second harmonic not only exists at the energy receiving end, but also when the signal source in the energy transmitting end circuit generates a linear frequency modulated continuous wave signal, it will also generate the second harmonic of the transmitting signal. The second harmonic signal generated by the signal source is expressed as S _k =ρ ₂ cos(2ω ₀ t+At ² ), so the embodiment of the present invention mixes the second harmonic at the energy transmitting end with the received second harmonic from the energy receiving end.

After the signal _Sk is mixed with the received second harmonic signal _SH , we get:

ρ ₂ represents the amplitude of the second harmonic signal at the energy transmitting end; mixing is achieved through a mixer, which is a three-terminal device with two input terminals and one output terminal. The output signal is equal to the product of the input signal, when The product of domains corresponds to the convolution of the frequency domain. Among them, cos[(4ω ₀ -2Aτ)t+2At ² +(Aτ ² -2ω ₀ )t] is filtered out, cos[2Atτ+(2ω ₀ τ-Aτ ² )]) represents the difference frequency signal, and the difference frequency signal After derivation of the phase, its frequency is obtained, expressed as/> Since τ=2R/c, where c represents the propagation speed of electromagnetic waves, therefore through the formula/> The distance R between the radio frequency energy receiving end and the radio frequency energy transmitting end can be determined (a collective name for the distances R ₁ , R ₂ , and R ₃ ). Frequency modulated continuous wave radar emits continuous waves with changing frequencies during the frequency sweep cycle. The echo reflected by the object has a certain frequency difference with the transmitted signal. By measuring the frequency difference, the distance information between the target and the radar can be obtained.

After the three radio frequency energy transmitting ends obtain the distance information from the radio frequency energy receiving end, the three-dimensional position coordinates of the radio frequency energy receiving end are solved through the positioning algorithm.

The principle of the positioning algorithm is shown in Figure 5. According to the positions of the three radio frequency energy transmitting ends in the spatial coordinate system, the coordinates of the radio frequency energy transmitting end one can be obtained as (x ₁ , y ₁ , z ₁ ), and the coordinates of the radio frequency energy transmitting end two are (x 1 , y 1 , z 1 ). The coordinates of are (x ₂ , y ₂ , z ₂ ), and the coordinates of radio frequency energy transmitting end 3 are (x ₃ , y ₃ , z ₃ ). Assume that the coordinates of the RF energy receiving end are (x, y, z), and the distance information to the RF energy receiving end is obtained based on the obtained three RF energy transmitting ends, RF energy transmitting end 1, RF energy transmitting end 2 and RF energy transmitting end The distances from the three radio frequency energy receiving ends are recorded as R ₁ , R ₂ , and R ₃ respectively. Since the three transmitting ends are not in the same plane, according to R ₁ , R ₂ , and R ₃ , the three radio frequency energy transmitting ends can be centered, The intersection of circles with R ₁ , R ₂ , and R ₃ as radii determines the location coordinates of the radio frequency energy receiving end, that is, the three-dimensional coordinates (x, y, z) of the receiving end are solved through the following set of equations;

Step S5: Based on the obtained position information of the receiving end, the three radio frequency energy transmitting ends adjust the beam center to the radio frequency energy receiving end in real time, so that the radio frequency energy receiving end obtains maximum energy, reduces energy loss, and improves the energy of the wireless energy transmission system. transmission efficiency.

The embodiment of the present invention utilizes the nonlinear physical characteristics of the rectifier diode in the rectifier circuit, uses the second harmonic signal generated by it to locate the energy receiving end, and designs a radio frequency wireless energy transmission system accordingly. First, in order to utilize the second harmonic signal generated by the energy receiving end circuit for positioning, the present invention uses three energy transmitting ends to transmit linear frequency modulated continuous wave signals. When the signals from the three energy transmitting ends reach the rectifier circuit at the energy receiving end, due to the nonlinear characteristics of the diodes in the rectifier circuit, the three transmitted signals S ₁ , S ₂ and S ₃ from the RF energy transmitting end are converted into electrical energy at the same time. Corresponding second harmonic signals S _r1 , S _r2 and S _r3 will be generated. Secondly, the second harmonic signal generated is weak. Although it will still radiate outward, it may not be captured at the energy receiving end. In order to feed back the second harmonic signal generated in the rectifier circuit to the three radio frequency energy transmitting ends , the embodiment of the present invention adds a second harmonic radiation antenna in the rectifier circuit, and uses the second harmonic radiation antenna to radiate the generated second harmonic signal to facilitate the reception of the radio frequency energy transmitting end. Finally, since the signals emitted by the three energy transmitting ends are non-coherent, the three energy transmitting ends respectively receive the second harmonic signal due to their transmitted signals, and then perform signal processing on the signals to obtain the energy receiving end. Based on the distances R ₁ , R ₂ , and R ₃ from itself, the three-dimensional position information of the energy receiving end can be calculated through the positioning algorithm proposed by the present invention. Through the obtained three-dimensional position information, the energy transmitting antenna beam at the energy transmitting end can be adjusted to point to the receiving antenna at the energy receiving end, thereby obtaining maximum energy transmission efficiency.

Compared with the existing technology, the present invention combines the advantages of radar systems and radar signal processing with wireless energy transmission systems, and proposes a long-distance, adaptive wireless energy transmission system that utilizes the rectifier diode itself at the energy receiving end. The second harmonic signal generated by the characteristic realizes the alignment of the energy transmitting end and the energy receiving end antenna. It does not consume the power of the energy receiving end. It only uses the antenna to radiate it out, and there is no need to add redundant hardware circuits at the energy receiving end. , has the advantages of higher energy transmission efficiency, less energy loss and simple circuit, and the system is more suitable for wireless energy transmission of low-power devices.

The above descriptions are only preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the protection scope of the present invention.

Claims (8)

1. A wireless energy transfer system utilizing second harmonic localization, comprising

The radio frequency energy transmitting ends are at least three and are non-coplanar, and each radio frequency energy transmitting end comprises

The energy transmitting device is used for transmitting the frequency modulation continuous wave signal; and

a second harmonic receiving antenna for receiving a second harmonic signal from the energy receiving end; and

the signal processing module is used for performing signal processing on the received second harmonic signal, acquiring the position information of the energy receiving end, feeding back the position information of the energy receiving end to the energy transmitting device, and adjusting the beam center to be aligned with the radio frequency energy receiving end in real time by the energy transmitting device;

the radio frequency energy receiving end comprises

The energy receiving rectifying antenna is used for receiving energy of the frequency modulation continuous wave signal from the energy transmitting end and converting the energy into electric energy, and in the process, a second harmonic wave is generated through the nonlinear device; and

the second harmonic radiation antenna is used for radiating out the second harmonic generated by the energy receiving rectifying antenna;

the frequency modulation continuous wave signals transmitted by the three radio frequency energy transmitting ends are respectively marked as S ₁ 、S ₂ And S is ₃ Signal S ₁ 、S ₂ And S is ₃ The second harmonic signals respectively generated by the radio frequency energy receiving ends are respectively marked as S _r1 、S _r2 And S is _r3 Based on the second harmonic signals corresponding to the radio frequency energy transmitting ends of three groups of different positions, the distance between the corresponding radio frequency energy transmitting end and the radio frequency energy receiving end is calculated and recorded as R ₁ 、R ₂ 、R ₃ Acquiring R with three radio frequency energy transmitting ends as the center ₁ 、R ₂ 、R ₃ The intersection point of three circles which are the radius is the position of the radio frequency energy receiving end;

the distance R between the radio frequency energy transmitting end and the radio frequency energy receiving end is determined according to the following formula:

wherein c represents the propagation velocity of electromagnetic wave, T _s The frequency sweep period is the period of the frequency modulation continuous wave signal; b is the bandwidth of the frequency modulation continuous wave signal, f _b And represents the frequency of the difference frequency signal, and τ is the transmission delay.

2. The wireless energy transfer system of claim 1, wherein said rf energy transmitting end further comprises

The signal source is used for generating an original frequency modulation continuous wave signal and converting electric energy into radio frequency energy;

and the power amplifier is used for amplifying the power of the generated signal and transmitting the amplified signal to the energy transmitting device.

3. A wireless energy transfer system using second harmonic positioning as in claim 1 wherein the energy receiving rectenna comprises

The energy receiving antenna is used for receiving the frequency modulation continuous wave signal transmitted by the energy transmitting device;

and the rectification circuit is used for converting radio frequency energy into electric energy and simultaneously radiating the generated second harmonic signal outwards through the second harmonic radiation antenna.

4. The wireless energy transmission system using second harmonic positioning of claim 1, wherein the fm continuous wave signals transmitted by the three rf energy transmitting terminals are non-coherent.

5. A wireless energy transmission method using second harmonic positioning, characterized in that a wireless energy transmission system using second harmonic positioning as claimed in claim 1 is adopted, specifically comprising the following steps:

step S1, an energy transmitting device of at least three radio frequency energy transmitting ends transmits out non-coherent frequency modulation continuous wave signals, the transmitted frequency modulation continuous wave signals propagate in space and are received by an energy receiving rectifying antenna of a radio frequency energy receiving end and converted into electric energy;

step S2, in the process of receiving the frequency modulation continuous wave signal, the nonlinear device generates second harmonic waves, and the second harmonic waves are radiated by the energy receiving rectifying antenna;

step S3, a second harmonic receiving antenna of the radio frequency energy transmitting end receives a second harmonic signal from the energy receiving end;

s4, the radio frequency energy transmitting terminal processes the received second harmonic signal through the signal processing module to acquire the position information of the energy receiving terminal;

and S5, feeding back the position information of the energy receiving end to the energy transmitting device by the signal processing module, and adjusting the beam center to be aligned with the radio frequency energy receiving end by the energy transmitting device in real time.

6. The wireless energy transmission method using second harmonic positioning according to claim 5, wherein in the steps S2 and S3, the second harmonic signal S emitted by the second harmonic radiation antenna of the rf energy receiving end ₀ Expressed as:wherein ρ is ₀ Amplitude, omega, of signal transmitted by second harmonic radiation antenna ₀ Representing the frequency, omega of the input signal ₀ ＝2πf ₀ A represents an intermediate parameter, a=2pi B/T _s ，T _s The frequency sweep period is the period of the frequency modulation continuous wave signal; t is time; b is the bandwidth of the frequency modulation continuous wave signal;

second harmonic signal S received by second harmonic receiving antenna of radio frequency energy transmitting end _H Expressed as: s is S _H ＝ρ ₁ cos(2ω ₀ (t-τ)+A(t-τ) ² ) Wherein ρ is ₁ The amplitude of the signal received by the second harmonic receiving antenna is represented, and tau is the transmission delay;

the circuit of the energy transmitting end generates a second harmonic signal S of the transmitting signal _k Expressed as: s is S _k ＝ρ ₂ cos(2ω ₀ t+At ² ) Wherein ρ is ₂ Representing the amplitude of a second harmonic signal generated by a circuit at the energy transmitting end;

signal S _k And S is equal to _H Mixing to obtain:

wherein the first term cos [ (4 omega) ₀ -2Aτ)t+2At ² +(Aτ ² -2ω ₀ )t]Filtered out, the second term cos [2Atτ+ (2ω) ₀ τ-Aτ ² )]Representing the difference frequency signal, the frequency of which is obtained after the phase derivation of the difference frequency signal, expressed as +.>Since τ=2r/c, where c represents the propagation velocity of electromagnetic waves, the formula +.>The distance R between the radio frequency energy receiving end and the radio frequency energy transmitting end can be determined.

7. The method of claim 6, wherein in step S4, the coordinates of the first rf energy transmitting end are obtained according to the positions of the three rf energy transmitting ends in the spatial coordinate system (x ₁ ,y ₁ ,z ₁ ) The coordinate of the second radio frequency energy transmitting end is (x) ₂ ,y ₂ ,z ₂ ) The three coordinates of the radio frequency energy transmitting end are (x) ₃ ,y ₃ ,z ₃ ) The method comprises the steps of carrying out a first treatment on the surface of the Assuming that the coordinates of the radio frequency energy receiving end are (x, y, z), the distances between the radio frequency energy transmitting end I, the radio frequency energy transmitting end II and the radio frequency energy transmitting end III and the radio frequency energy receiving end are respectively recorded as R ₁ 、R ₂ 、R ₃ Because the three radio frequency energy emitting ends are not on the same plane, the three radio frequency energy emitting ends are taken as the center and R is taken as the center ₁ 、R ₂ 、R ₃ The intersection point of the three circles is the position coordinate of the radio frequency energy receiving end.

8. The wireless energy transmission method using second harmonic localization of claim 7, wherein the coordinates of the rf energy receiving end are (x, y, z) solved by the following equation: