Directional transmission method based on golden section in microwave wireless power transmission system

Abstract

The present invention discloses a directional transmission method based on the golden section in a microwave wireless power transmission system, belonging to the technical field of electrical communications. The present invention first establishes an N-channel transmitting antenna array, activates transmitting channel 1, and initializes its phase shift angle. Next, guided by maximizing received power, the phase shift angles of the remaining N−1 channels, excluding transmitting channel 1, are adjusted sequentially, including coarse adjustment and fine adjustment based on the golden section method. Finally, the phase shift angles of all N channels are adjusted, all transmitting channels are activated, and the receiving end power reaches maximum, achieving directional transmission of microwave power. The present invention uses a coarse adjustment method to lock the starting fine adjustment range of the phase shift angle in large steps, and uses the golden section method to quickly optimize the fine adjustment range of the phase shift angle, thereby improving the search speed for the optimal phase shift angle of the transmitting antenna subarray.

Description

Technical Field

[0001] The invention relates to microwave wireless power transmission technology, discloses a directional emission method based on golden section in a microwave wireless power transmission system, and belongs to the technical field of electrical communications. Background Art

[0002] Microwave wireless power transmission technology has flourished in recent years. It enables wireless power transmission over long distances, avoiding the cable losses and high maintenance costs associated with traditional wired power transmission. Microwave wireless power transmission can achieve directional power transmission through the alignment of transmitting and receiving antennas. Unrestricted by natural conditions such as terrain and topography, it is applicable to a wide range of environments and applications.

[0003] Directional transmission technology can significantly improve energy utilization and system efficiency. Traditional microwave directional transmission technology can be implemented primarily through two methods: open-loop directional transmission based on the phased array principle. The phase shift angle is determined based on the known positions of the transmit and receive antennas, and each subarray of the transmit antenna is fed based on this phase shift angle. The second directional transmission method, based on the superposition principle, scans the phase shift angle of each transmit antenna subarray in small steps over a range of 0° to 360°, records and selects the phase shift angle that maximizes received power, and then feeds each transmit antenna subarray based on this selected phase shift angle. The first microwave directional transmission technology can theoretically achieve directional power transmission, but due to errors in the manufacture, installation, and actual use of the transmit antenna, the actual transmission angle deviates from the theoretically calculated value. While this can be corrected through phase calibration, the calibration workload increases dramatically as the number of subarrays increases, making its engineering application value lower. The second microwave directional transmission technology requires scanning the phase shift angle of all transmit antenna channels in small steps, which is labor-intensive and time-consuming. Therefore, it is necessary to find a method that is universal, simple, effective and can quickly achieve power-directional transmission. Summary of the Invention

[0004] The purpose of the present invention is to address the deficiencies of the above-mentioned background technology and propose a directional transmission method based on the golden section in a microwave wireless power transmission system to solve the technical problems of the existing directional transmission method such as the transmission angle deviation and the long time-consuming scheme. The starting fine-tuning interval of the phase shift angle is locked in a large step by a coarse adjustment method, and the golden section method is used to quickly optimize the fine-tuning interval of the phase shift angle, thereby improving the search speed of the optimal phase shift angle of the transmitting antenna subarray, thereby ensuring that each transmitting antenna channel operates at the optimal phase shift angle, maximizing the receiving end power, and achieving the invention purpose of microwave power directional transmission.

[0005] The technical solutions adopted by the present invention to achieve the above-mentioned purpose are as follows:

[0006] The directional transmission method based on the golden section in a microwave wireless power transmission system includes the following steps:

[0007] Step 1: Open the first transmitting channel and initialize the phase shift angle of the first transmitting channel to zero;

[0008] Step 2: For the remaining transmit channels, perform phase shift angle coarse adjustment and phase shift angle fine adjustment in sequence. The phase shift angle fine adjustment optimizes the phase shift angle fine adjustment intervals of the remaining transmit channels using the golden section algorithm. The fine adjustment phase shift angles of the remaining transmit channels are determined based on the phase shift angle fine adjustment intervals of the remaining transmit channels. The initial fine adjustment intervals of the phase shift angles of the remaining transmit channels are determined by the coarse adjustment phase shift angles obtained by the coarse adjustment of the phase shift angle.

[0009] Step 3: The first transmitting channel operates at a phase shift angle below zero, and the remaining transmitting channels operate at their respective fine-tuned phase shift angles.

[0010] As a further optimization scheme for the directional transmission method based on the golden section in the microwave wireless power transmission system, the coarse adjustment of the phase shift angle in step 2 is specifically as follows: turning on the remaining transmission channels, and judging the adjustment direction and coarse adjustment range of the phase shift angle of the remaining transmission channels based on the received power of the remaining transmission channels when operating at phase shift angles of opposite positive and negative but the same value; and searching within the coarse adjustment range of the phase shift angle of the remaining transmission channels for a coarse adjustment phase shift angle that makes the current received power greater than the maximum received power based on the adjustment direction of the phase shift angle of the remaining transmission channels.

[0011] As a further optimization scheme for the golden section-based directional transmission method in microwave wireless power transmission systems, the phase shift angle fine adjustment optimizes the phase shift angle fine adjustment intervals of the remaining transmission channels through the golden section algorithm, with the goal of maximizing the received power. The optimization is stopped when the span of the phase shift angle fine adjustment intervals of the remaining transmission channels is less than the fine adjustment phase shift angle accuracy.

[0012] As a further optimization scheme of the directional transmission method based on the golden section in the microwave wireless power transmission system, the fine-tuning phase shift angles of the remaining transmission channels are the middle values ​​of the final optimized phase shift angle fine-tuning range.

[0013] As a further optimization scheme for the golden section-based directional transmission method in microwave wireless power transmission systems, the coarse phase shift angle adjustment specifically includes the following steps:

[0014] Step a: Initialize the index i=2 of the remaining transmission channels. If i is less than or equal to N, proceed to step b. Otherwise, proceed to step 3. N is the total number of transmission channels.

[0015] Step b: Turn on the transmitting channel i and record the receiving power P when the transmitting channel i works at the phase shift angle α° and -α°. ri(α) and P ri(-α) , P ri(α) >Pri(-α) , the adjustment direction of the phase shift angle of the transmitting channel i is positive and the coarse adjustment range is [0°, 180°], otherwise, the adjustment direction of the phase shift angle of the transmitting channel i is negative and the coarse adjustment range is [180°, 360°];

[0016] Step c, initializing the coarse adjustment index j = 0; when the adjustment direction of the phase shift angle of transmit channel i is positive, take (180 / α+1) phase shift angles in the interval [0°, 180°] with an interval of α°; when the adjustment direction of the phase shift angle of transmit channel i is negative, take (180 / α+1) phase shift angles in the interval [180°, 360°] with an interval of -α°;

[0017] In step d, if j is less than or equal to 180 / α, proceed to step e; otherwise, proceed to step m;

[0018] Step e: Calculate the coarse phase shift angle Phs of the transmitting channel i according to the value of the coarse index j. i =(αj)°, records the received power P when the transmitting channel i works at the phase shift angle (αj)° rij ;

[0019] Step f, the received power P when the transmitting channel i works at the phase shift angle (αj)° rij When it is greater than the maximum received power, the updated maximum received power is the received power P when the transmitting channel i works at the phase shift angle (αj)° rij , and record the value of the coarse adjustment index j, otherwise, go to step g;

[0020] Step g, j=j+1, return to step d.

[0021] As a further optimization solution for the golden section-based directional transmission method in microwave wireless power transmission systems, fine adjustment of the phase shift angle specifically includes the following steps:

[0022] Step m, compare the received power P when the transmitting channel i works at the phase shift angle (α(k-1))° ri(k-1) The received power P when the transmitting channel i works at a phase shift angle (α(k+1))° ri(k+1) , k is the fine adjustment index, and the initial value of k is the coarse adjustment index value corresponding to the coarse adjustment phase shift angle that makes the current received power greater than the maximum received power during the phase shift angle coarse adjustment process; P ri(k-1) ≤P ri(k+1) Or k=0, then initialize the phase shift angle fine adjustment interval [a, b] of the transmitting channel i to [α°k, α°(k+1)]; P ri(k-1) >P ri(k+1) Or k = 180 / α, then the initialization phase shift angle fine adjustment interval [a, b] of transmit channel i is [α°(k-1),α°k];

[0023] Step n, initializing the first phase shift angle θ1, the second phase shift angle θ2, the golden section ratio β and the fine adjustment phase shift angle accuracy ε, θ1 = 0°, θ2 = 0°, β = 0.618;

[0024] Step o, let θ1 = b-β(ba), record the received power P when the transmitting channel i works at the first phase shift angle θ1 ri(θ1) ; Let θ2 = a + β (ba), record the received power P when the transmitting channel i works at the second phase shift angle θ2 ri(θ2) ;

[0025] Step p, P ri(θ1) ≥P ri(θ2) , then b=θ2,θ2=θ1,P ri(θ2) =P ri(θ1) , let θ1 = b-β(ba) and record the received power P of the transmitting channel i when it works at the current first phase shift angle θ1 ri(θ1) ;P ri(θ1) <P ri(θ2) , then a=θ1,θ1=θ2,P ri(θ1) =P ri(θ2) , let θ2 = a + β(ba) and record the received power P of the transmitting channel i when it works at the current second phase shift angle θ2 ri(θ2) ;

[0026] Step q, ba<ε, then set the transmission channel i to fine-tune the phase shift angle Phs i If it is [(a+b) / 2]°, go to step r, otherwise, return to step p;

[0027] Step r, i=i+1, return to step a.

[0028] The present invention adopts the above technical solution and has the following beneficial effects:

[0029] (1) The directional transmission method based on the golden section in the microwave wireless power transmission system proposed in the present invention maximizes the linear superposition of the field strengths generated by the N sub-arrays of the transmitting antenna by optimizing the phase shift angle by coarse adjustment first and then fine adjustment, thereby maximizing the received power and improving energy utilization and system efficiency. The method is applicable to optimizing the phase shift angle of any N-channel transmitting antenna array and has strong universality.

[0030] (2) The directional transmission method based on the golden section in the microwave wireless power transmission system proposed in the present invention is to coarse-tune the phase shift angle of each channel in turn and then fine-tune it based on the golden section method. The coarse adjustment process narrows the coarse adjustment interval by determining the phase shift angle adjustment direction, and then searches for the coarse adjustment phase shift angle that maximizes the received power in large steps within the coarse adjustment interval, and then determines the initial fine adjustment interval. Combined with the golden section algorithm, the fine adjustment interval is quickly optimized and the final fine adjustment phase shift angle is locked, which can greatly reduce the time spent on optimizing the phase shift angle, and thus reduce the time spent on power directional transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1(a) shows the electric field generated by N sub-arrays of transmitting antennas under ideal conditions.

[0032] Figure 1(b) shows the electric field that may actually be generated by N sub-arrays of transmitting antennas.

[0033] FIG1(c) is a diagram of the electric field vectors generated by rotating and correcting the N subarrays of the transmitting antenna.

[0034] Figure 2 This is an algorithm flow chart of the directional transmission method based on the golden section in the microwave wireless power transmission system proposed in the present invention.

[0035] Figure 3(a) shows the method proposed in the present invention in P ri(θ1) ≥P ri(θ2) Schematic diagram of the received power when .

[0036] Figure 3(b) shows the method proposed in the present invention in P ri(θ1) <P ri(θ2) Schematic diagram of the received power when .

[0037] Figure 4(a) shows the method proposed in the present invention in P ri(θ1) ≥P ri(θ2) Schematic diagram of the phase shift angle optimization direction based on the golden section method.

[0038] Figure 4(b) shows the method proposed in the present invention in P ri(θ1) <P ri(θ2) Schematic diagram of the phase shift angle optimization direction based on the golden section method. DETAILED DESCRIPTION

[0039] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0040] The electric field generated by N subarrays of a transmitting antenna under ideal conditions is shown in Figure 1(a). Since received power is proportional to the square of the field strength at the receiving end, and the field strength at the receiving end is the linear sum of the field strengths generated by the N subarrays, ideally, received power is maximized when the field strengths generated by the N subarrays are in phase. However, due to errors in antenna manufacturing, installation, and actual use, the angles of the field strength vectors generated by the N subarrays may vary. The actual electric field generated by N subarrays of a transmitting antenna is shown in Figure 1(b). To maximize received power, the phase shift angle must be adjusted to rotate and correct the electric field vectors generated by the N subarrays, as shown in Figure 1(c).

[0041] Figure 2 The figure shows the algorithm flow chart for the golden section-based directional transmission method in the microwave wireless power transmission system proposed in this invention. The core concept of this algorithm is that, based on the principle of field strength superposition, when the field strength generated by each transmitting antenna subarray at the receiving end reaches its maximum, the total field strength at the receiving end reaches its maximum, and the received power is maximized. Directed power transmission is achieved by recording and selecting the phase shift angle that maximizes the received power for each channel. The specific algorithm flow is as follows, including steps 1 to 3.

[0042] Step 1: First, establish an N-channel transmit antenna array, make sure all transmit channels are closed, only open transmit channel 1, and set its phase shift angle Phs1 = 0°; set the initial transmit channel index i = 2 and the initial maximum receive power P ri_max =0.

[0043] Step 2: Adjust the phase shift angles of the remaining N-1 channels except channel 1 in sequence, specifically including steps 2.1 and 2.2, until the coarse adjustment and fine adjustment of the phase shift angles of all transmitting channels are completed.

[0044] Step 2.1: Coarsely adjust the phase shift angle of transmit channel i, specifically including steps a to g, until the coarse adjustment of the phase shift angle of channel i is completed:

[0045] Step a: Determine whether the transmit channel index i is less than or equal to the number of channels N, that is, whether the phase shift angles of N-1 transmit channels have been adjusted. If the phase shift angle adjustment of any transmit channel is not completed, proceed to step b to adjust the remaining unadjusted phase shift angles in sequence. Otherwise, proceed to step 3, where N is the total number of transmit channels, that is, the number of transmit antenna subarrays.

[0046] Step b: Adjust the other unadjusted phase shift angles in sequence. First, start the transmit channel i for coarse adjustment, and set the phase shift angle Phs of the transmit channel i in sequence. i For α° and -α°, the received power is recorded as P ri(α) and P ri(-α) , if P ri(α) >Pri(-α) , the phase shift angle adjustment direction is positive, and the coarse adjustment interval is [0°, 180°]. Otherwise, the phase shift angle adjustment direction is negative, and the coarse adjustment interval is [180°, 360°]. The following steps are analyzed based on the positive adjustment of the phase shift angle and the coarse adjustment interval of [0°, 180°]. The coarse adjustment process of the negative adjustment of the phase shift angle and the coarse adjustment interval of [180°, 360°] also uses steps c to g to coarsely adjust the transmission angle of transmission channel i;

[0047] Step c, set the initial coarse adjustment index j = 0, take (180 / α+1) phase shift angles in the interval [0°, 180°] with α° as the interval;

[0048] Step d: Determine whether the coarse adjustment index j is less than or equal to 180 / α, that is, whether all (180 / α+1) phase shift angles of transmit channel i in the interval [0°, 180°] have been scanned. If the scan is not complete, proceed to step e to continue scanning the phase shift angles; otherwise, proceed to step 2.2.

[0049] Step e: Scan the phase shift angle and record the corresponding received power, and set the coarse phase shift angle Phs of the transmitting channel i. i =(αj)°, record the received power P rij ;

[0050] Step f, determine P rij Is it greater than P ri_max , that is, to judge P rij Is it the maximum received power currently recorded? If P rij is the maximum received power currently recorded, then update the maximum received power P ri_max =P rij And set the fine adjustment index k=j and then go to step g, otherwise go directly to step g;

[0051] In step g, set j=j+1 and then return to step d to continue the coarse adjustment cycle of the phase shift angle of the transmitting channel i until the coarse adjustment index j is greater than 180 / α, and then enter step 2.2 to start fine adjustment of the phase shift angle of channel i.

[0052] Step 2.2: Fine-tune the phase shift angle of each transmit channel, specifically including steps m to r, until the fine-tuning of the phase shift angle of transmit channel i is completed:

[0053] Step m, determine the fine-tuning interval according to the situation: if P ri(k-1) ≤P ri(k+1) Or k=0, then initialize the phase shift angle fine adjustment interval [a,b] of transmit channel i to [α°k,α°(k+1)]; if P ri(k-1) >P ri(k+1)Or k = 180 / α, then the initialization phase shift angle fine adjustment interval [a, b] of transmit channel i is [α°(k-1),α°k];

[0054] Step n, initializing the first phase shift angle and the second phase shift angle, θ1 = 0°, θ2 = 0°, setting the golden ratio β = 0.618, and fine-tuning the phase shift angle accuracy ε = 2;

[0055] Step o, locate the first phase shift angle θ1 and the second phase shift angle θ2 to the two golden section points in the fine adjustment interval [a, b], and record the corresponding received power: let θ1 = b-β(ba), record the received power P ri(θ1) ; Let θ2 = a + β (ba), record the received power P ri(θ2) ;

[0056] Step p, judge P ri(θ1) Is it greater than or equal to P ri(θ2) , that is, to determine the optimal direction of the phase shift angle based on the golden section method, if P ri(θ1) ≥P ri(θ2) , then the received power diagram is shown in Figure 3(a), and the information of the optimal direction of the phase shift angle is updated according to Figure 4(a): b = θ2, θ2 = θ1, P ri(θ2) =P ri(θ1) , let θ1 = b-β(ba) and record the received power P ri(θ1) Otherwise, the received power diagram is shown in Figure 3(b). According to the phase shift angle optimization direction update information shown in Figure 4(b): a=θ1,θ1=θ2,P ri(θ1) =P ri(θ2) , let θ2=a+β(ba) and record the received power P ri(θ2) ;

[0057] Step q, determine whether ba is less than 2, that is, determine whether the fine adjustment interval span is less than the fine adjustment phase angle accuracy ε. If ba<2, set the fine adjustment phase angle Phs of the transmitting channel i. i If the value is [(a+b) / 2]°, the process goes to step r. Otherwise, the process goes back to step p and continues to optimize the fine-tuning phase shift angle of the transmitting channel i based on the golden section method.

[0058] In step r, set i=i+1 and then return to step a until the phase shift angles of N-1 channels are adjusted, and then proceed to step 3.

[0059] Step 3: The phase shift angles of the N channels of the transmitting antenna array are adjusted, all transmitting channels are turned on, the receiving end power reaches the maximum, and directional transmission of microwave power is achieved.

[0060] The above embodiments are only for illustrating the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. A directional transmission method based on the golden section in a microwave wireless power transmission system, characterized in that: The steps include: Step 1: Open the first transmitting channel and initialize the phase shift angle of the first transmitting channel to zero; Step 2: For the remaining transmission channels, perform phase shift angle coarse adjustment and phase shift angle fine adjustment in turn. The coarse adjustment of the phase shift angle is specifically as follows: turning on the remaining transmit channels, and determining the adjustment direction and coarse adjustment range of the phase shift angles of the remaining transmit channels according to the received power of the remaining transmit channels when operating at phase shift angles of opposite sign but the same value; According to the phase shift angle adjustment direction of the remaining transmission channels, search for the coarse adjustment phase shift angle that makes the current received power greater than the maximum received power within the coarse adjustment range of the phase shift angle of the remaining transmission channels. The phase shift angle fine adjustment optimizes the phase shift angle fine adjustment intervals of the remaining transmission channels by using a golden section algorithm, with the goal of maximizing received power. The optimization is stopped when the span of the phase shift angle fine adjustment intervals of the remaining transmission channels is less than the fine adjustment phase shift angle precision. The fine adjustment phase shift angles of the remaining transmission channels are determined based on the phase shift angle fine adjustment intervals of the remaining transmission channels. The initial fine adjustment intervals of the phase shift angles of the remaining transmission channels are determined by the coarse adjustment phase shift angles obtained by the coarse adjustment of the phase shift angle. Step 3: the first transmitting channel operates at a phase shift angle below zero, and the remaining transmitting channels operate at their respective fine-tuning phase shift angles.

2. The directional transmission method based on golden section in the microwave wireless power transmission system according to claim 1, characterized in that: The fine-tuning phase shift angles of the remaining transmitting channels are intermediate values ​​of the final optimized phase shift angle fine-tuning interval.

3. The directional transmission method based on golden section in the microwave wireless power transmission system according to claim 1 or 2, characterized in that: The phase shift angle coarse adjustment specifically includes the following steps: Step a: Initialize the index i=2 of the remaining transmission channels. If i is less than or equal to N, proceed to step b. Otherwise, proceed to step 3. N is the total number of transmission channels. Step b: Turn on the transmitting channel i and record the receiving power P when the transmitting channel i works at the phase shift angle α° and -α°. ri(α) and P ri(-α) , P ri(α) >P ri(-α) , the adjustment direction of the phase shift angle of the transmitting channel i is positive and the coarse adjustment range is [0°, 180°], otherwise, the adjustment direction of the phase shift angle of the transmitting channel i is negative and the coarse adjustment range is [180°, 360°]; Step c, initializing the coarse adjustment index j = 0; when the adjustment direction of the phase shift angle of transmit channel i is positive, take (180 / α+1) phase shift angles in the interval [0°, 180°] with an interval of α°; when the adjustment direction of the phase shift angle of transmit channel i is negative, take (180 / α+1) phase shift angles in the interval [180°, 360°] with an interval of -α°; In step d, if j is less than or equal to 180 / α, proceed to step e; otherwise, proceed to step m; Step e: Calculate the coarse phase shift angle Phs of the transmitting channel i according to the value of the coarse index j. i =(αj)°, records the received power P when the transmitting channel i works at the phase shift angle (αj)° rij ; Step f, the received power P when the transmitting channel i works at the phase shift angle (αj)° rij When it is greater than the maximum received power, the updated maximum received power is the received power P when the transmitting channel i works at the phase shift angle (αj)° rij , and record the value of the coarse adjustment index j, otherwise, go to step g; Step g, j=j+1, return to step d.

4. The directional transmission method based on golden section in the microwave wireless power transmission system according to claim 3, characterized in that: The phase shift angle fine adjustment specifically includes the following steps: Step m, compare the received power P when the transmitting channel i works at the phase shift angle (α(k-1))° ri(k-1) The received power P when the transmitting channel i works at a phase shift angle (α(k+1))° ri(k+1) , k is the fine adjustment index, and the initial value of k is the coarse adjustment index value corresponding to the coarse adjustment phase shift angle that makes the current received power greater than the maximum received power during the phase shift angle coarse adjustment process; P ri(k-1) ≤P ri(k+1) Or k=0, then initialize the phase shift angle fine adjustment interval [a, b] of the transmitting channel i to [α°k, α°(k+1)]; P ri(k-1) >P ri(k+1) Or k = 180 / α, then the initialization phase shift angle fine adjustment interval [a, b] of transmit channel i is [α°(k-1),α°k]; Step n, initializing the first phase shift angle θ1, the second phase shift angle θ2, the golden section ratio β and the fine adjustment phase shift angle accuracy ε, θ1 = 0°, θ2 = 0°, β = 0.618; Step o, let θ1 = b-β(ba), record the received power P when the transmitting channel i works at the first phase shift angle θ1 ri(θ1) ; Let θ2 = a + β (ba), record the received power P when the transmitting channel i works at the second phase shift angle θ2 ri(θ2) ; Step p, P ri(θ1) ≥P ri(θ2) , then b=θ2,θ2=θ1,P ri(θ2) =P ri(θ1) , let θ1 = b-β(ba) and record the received power P of the transmitting channel i when it works at the current first phase shift angle θ1 ri(θ1) ;P ri(θ1) <P ri(θ2) , then a=θ1,θ1=θ2,P ri(θ1) =P ri(θ2) , let θ2 = a + β(ba) and record the received power P of the transmitting channel i when it works at the current second phase shift angle θ2 ri(θ2) ; Step q, ba<ε, then set the transmission channel i to fine-tune the phase shift angle Phs i If it is [(a+b) / 2]°, go to step r, otherwise, return to step p; Step r, i=i+1, return to step a.

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