CN112968535B - Load coil position detection method for omnidirectional wireless power transmission system - Google Patents

Load coil position detection method for omnidirectional wireless power transmission system Download PDF

Info

Publication number
CN112968535B
CN112968535B CN202110344895.0A CN202110344895A CN112968535B CN 112968535 B CN112968535 B CN 112968535B CN 202110344895 A CN202110344895 A CN 202110344895A CN 112968535 B CN112968535 B CN 112968535B
Authority
CN
China
Prior art keywords
current
calculating
moment
direct current
time
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202110344895.0A
Other languages
Chinese (zh)
Other versions
CN112968535A (en
Inventor
孙向东
张昭阳
任碧莹
王之轩
陈泽驰
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Xian University of Technology
Original Assignee
Xian University of Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Xian University of Technology filed Critical Xian University of Technology
Priority to CN202110344895.0A priority Critical patent/CN112968535B/en
Publication of CN112968535A publication Critical patent/CN112968535A/en
Application granted granted Critical
Publication of CN112968535B publication Critical patent/CN112968535B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
    • H02J50/90—Circuit arrangements or systems for wireless supply or distribution of electric power involving detection or optimisation of position, e.g. alignment
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/7072—Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Power Engineering (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)

Abstract

The invention provides a load coil position detection method for an omnidirectional wireless power transmission system, which converts the problem of load coil position detection in a two-dimensional and three-dimensional omnidirectional WPT system into the problem of input power maximization search of the omnidirectional WPT system after mathematical modeling analysis. The optimal step angle is calculated based on the gradient descent method of the Barz i a i-Borwe i n method, so that the optimal step angle in each iteration process can be realized, the iteration times are reduced, the current injected into the three-phase orthogonal transmitting coil is rapidly disturbed, the rapid search of the maximum input power is realized, the purpose of rapidly positioning the position of the load coil is achieved, and the maximum transmission efficiency is realized.

Description

Load coil position detection method for omnidirectional wireless power transmission system
Technical Field
The invention belongs to the technical field of wireless power transmission, and relates to a load coil position detection method for an omnidirectional wireless power transmission system.
Background
Wireless power transfer (Wireless Power Transfer, WPT) technology has become an emerging solution for charging electronic devices due to its convenience and security. With the gradual use of WPT, more and more electronic products, such as smartphones, smartwatches, tablet computers, and notebook computers, support wireless charging. In general, mobile electronic products such as mobile phones and smart watches need to be fixed on a charging board during charging, and users cannot freely use equipment during charging, which is inconvenient in practical use, unlike users hope, and the mobile electronic products can still freely use equipment during charging in the same way as traditional wired charging.
To solve the above problems, more and more students are beginning to pay attention to the problem of spatial freedom of WPT system. For the WPT system with the conventional two-coil and four-coil structure, the generated magnetic field points to a specific direction, and if the receiving coil is shifted in position or rotated, the transmission efficiency is greatly reduced, so that the conventional two-coil and four-coil structure is not suitable for application occasions with high requirements on movement, particularly for intelligent wearable equipment. In order to improve the space freedom of the wireless power transmission system, an effective solution is to use a multiphase orthogonal transmitting coil, generate an omnidirectional magnetic vector by using a current control method, and obtain omnidirectional wireless power transmission capability regardless of whether the wireless power transmission system moves or not. Studies have shown that transmitting wireless power directly to a target load is the most energy efficient method, rather than transmitting power in all directions. Therefore, in order to improve the transmission efficiency and reduce the charging time, the difficulty of the solution is that in practical application, it is difficult to obtain the position information of the load coil (i.e. the receiving coil) in real time, and directional transmission of the wireless power to the load coil cannot be guaranteed, so that the highest transmission efficiency of the system cannot be realized. Current amplitude modulation in the existing current control method is most suitable for realizing directional transmission of wireless power to a load coil. Based on the current control method, the current method for detecting the position of the load coil is to inject current into three orthogonal transmitting coils to sequentially generate a plurality of magnetic vectors, each magnetic vector is coupled with the magnetic field of the load coil, all the magnetic vectors are scanned once, a distorted spherical surface is generated, and the position corresponding to the magnetic vector added when the distortion degree is maximum is the position where the load coil is located. It can be seen that a large number of magnetic vectors need to be scanned once each time a load coil position detection is performed, so this approach is not suitable for frequently moving load coil position detection.
It is noted that this section is intended to provide a background or context for the embodiments of the invention that are recited in the claims. The description herein is not admitted to be prior art by inclusion in this section.
Disclosure of Invention
The invention aims to provide a load coil position detection method for an omnidirectional wireless power transmission system, which can rapidly position the load coil position and realize maximum transmission efficiency.
The invention adopts the following technical scheme to realize the purposes:
the method for detecting the position of the load coil of the omnidirectional wireless power transmission system comprises the following steps:
s1: setting initial parameters
Establishing a mathematical model of an omnidirectional wireless power transmission system, and setting theta and theta
Figure BDA0002998591280000021
For the physical angle of the synthesized current vector on the three-dimensional plane, the input power P in the initial state is obtained according to the sampled direct current voltage and direct current in (0, 0), proceeding to step S2; wherein θ is the current vector +.>
Figure BDA0002998591280000022
Forward included angle with Z axis, +.>
Figure BDA0002998591280000023
For current vector->
Figure BDA0002998591280000024
The projection on the XOY plane forms an included angle with the positive X axis;
s2: calculating initial state information
Calculating information of an initial state based on a gradient descent method of a Barzilai-Borwein method;
s3: calculating the theta partial derivative of the objective function at the moment k;
calculating the given value of each phase transmitting coil current at the present moment, executing current control, and obtaining the input power at the k moment according to the sampled direct current voltage and direct current after the current is stabilized
Figure BDA0002998591280000031
Then calculate the target function of k momentPartial derivative of θ ->
Figure BDA0002998591280000032
S4: calculating the relation of the objective function at the moment k
Figure BDA0002998591280000033
Partial derivative;
calculating the given value of the current of each phase transmitting coil at the present moment, and executing current control; after the current is stabilized, obtaining the input power at the moment k according to the sampled direct current voltage and direct current
Figure BDA0002998591280000034
Figure BDA0002998591280000035
Calculating the k moment objective function about +.>
Figure BDA0002998591280000036
Partial derivative of>
Figure BDA0002998591280000037
S5: θ partial derivative sum based on k moment objective function
Figure BDA0002998591280000038
Calculating the optimal step length alpha by partial derivative;
s6: according to the calculated optimal step length alpha, theta (k+1) and theta (alpha+1) at the moment of k+1 are obtained
Figure BDA0002998591280000039
S7: the θ (k+1) at time k+1 is added to
Figure BDA00029985912800000310
Assigning values to θ and +.>
Figure BDA00029985912800000311
Calculating the current transmitting coilsThe current value, after the current is stable, the input power of k+1 moment is obtained according to the sampled direct current voltage and direct current>
Figure BDA00029985912800000312
And will be
Figure BDA00029985912800000313
Assign->
Figure BDA00029985912800000314
S8: saving information at the moment k, completing one iteration based on a Barzilai-Borwein method gradient descent method, adding 1 to iteration times N, and entering a step 9;
s9: if the maximum iteration number or the objective function value calculated by two iterations is reached
Figure BDA00029985912800000315
If the set error requirement is met, ending the iteration and outputting theta (k) and +.>
Figure BDA00029985912800000316
The actual physical position of the load coil; if none of them meets the setting error requirement, θ (k) and +.>
Figure BDA00029985912800000317
Assigning values to θ and +.>
Figure BDA00029985912800000318
And returning to the step S3.
Further, the step S2 specifically includes:
s201: calculating the partial derivative of the initial state objective function;
calculating the given value of the current of the three-phase transmitting coil at the present moment according to the formula (20), performing current control, and obtaining the input power P in the initial state according to the sampled direct current voltage and the sampled direct current after the current is stabilized in (Δθ, 0), and P in (Δθ, 0) is given to F (Δθ, 0);
Figure BDA0002998591280000041
from equation (21), the partial derivative of the initial state objective function with respect to θ can be calculated
Figure BDA0002998591280000042
And assign it +.>
Figure BDA0002998591280000043
Figure BDA0002998591280000044
S202: calculating initial state objective function
Figure BDA0002998591280000045
Is a partial derivative of (2);
calculating a given value of the current of the three-phase transmitting coil at the present moment according to a formula (22), and executing current control; after the current is stabilized, obtaining the input power in the initial state according to the sampled direct current voltage and direct current
Figure BDA0002998591280000046
And will be
Figure BDA0002998591280000047
Assign->
Figure BDA0002998591280000048
Figure BDA0002998591280000049
From equation (23), the initial state objective function is calculated
Figure BDA00029985912800000410
Partial derivative of>
Figure BDA00029985912800000411
And assign it +.>
Figure BDA00029985912800000412
Figure BDA00029985912800000413
S203: calculating the input power at the next moment
Figure BDA00029985912800000414
Calculating the given value of the current of each phase transmitting coil at the next moment according to the formula (24), and executing current control; after the current is stabilized, obtaining the input power at the next moment according to the sampled direct current voltage and direct current
Figure BDA00029985912800000415
And will be
Figure BDA00029985912800000416
Assign->
Figure BDA00029985912800000417
Figure BDA00029985912800000418
Storing the current time information according to a formula (25), wherein alpha takes a value of 0.5; and sum θ (k) of the current time
Figure BDA00029985912800000419
Assigning values to θ and +.>
Figure BDA00029985912800000420
Step S3 is entered;
Figure BDA0002998591280000051
further, the step S3 specifically includes:
calculating the given value of each phase transmitting coil current at the present moment according to the formula (26), performing current control, and obtaining the input power at the k moment according to the sampled direct current voltage and direct current after the current is stabilized
Figure BDA0002998591280000052
/>
Figure BDA0002998591280000053
Calculating the partial derivative of the objective function at the moment k with respect to θ from the equation (27)
Figure BDA0002998591280000054
And assign it +.>
Figure BDA0002998591280000055
Step S4 is entered;
Figure BDA0002998591280000056
further, the step S4 specifically includes:
calculating the given value of the current of each phase transmitting coil at the present moment according to the formula (28), and executing current control; after the current is stabilized, obtaining the input power at the moment k according to the sampled direct current voltage and direct current
Figure BDA0002998591280000057
And will be
Figure BDA0002998591280000058
Assign->
Figure BDA0002998591280000059
Figure BDA00029985912800000510
Calculating the k moment objective function from the formula (29)
Figure BDA00029985912800000511
Partial derivative of>
Figure BDA00029985912800000512
Figure BDA00029985912800000513
Further, the step S5 specifically includes:
definition of s according to the Barzilai-Borwein method k 、z k ：
Figure BDA0002998591280000061
Wherein s is k The vector difference, denoted as search points at time k and time k-1; z k The gradient difference of the search point vector is expressed as k time and k-1 time; x is x k A vector denoted as search point at time k; x is x k-1 A vector denoted as the search point at time k-1;
Figure BDA0002998591280000062
a gradient denoted as a search point vector at time k; />
Figure BDA0002998591280000063
A gradient denoted as a search point vector at time k-1;
calculating the optimal step length alpha according to the formula (31), and entering a step S6;
Figure BDA0002998591280000064
further, the step S6 specifically includes:
from the calculated optimal step alpha, the k+1 time θ (k+1) and the k+1 time θ can be calculated from the equation (32)
Figure BDA0002998591280000065
And proceeds to step S7; />
Figure BDA0002998591280000066
Further, the step S8 specifically includes:
storing information at the k moment according to a formula (33), completing one iteration of a gradient descent method based on a Barzilai-Borwein method, adding 1 to iteration times N, and entering a step S9;
Figure BDA0002998591280000067
the invention has the beneficial effects that:
the load coil position detection method for the omnidirectional wireless power transmission system is suitable for the two-dimensional and three-dimensional omnidirectional WPT system, and converts the problem of load coil position detection in the two-dimensional and three-dimensional omnidirectional WPT system into the problem of input power maximization search of the omnidirectional WPT system after mathematical modeling analysis. The optimal step angle is calculated based on the gradient descent method of the Barzilai-Borwein method, so that the optimal step angle in each iteration process can be realized, the iteration times are reduced, the current injected into the three-phase orthogonal transmitting coil is rapidly disturbed, the rapid search of the maximum input power is realized, the purpose of rapidly positioning the position of the load coil is achieved, and the maximum transmission efficiency is realized.
Drawings
Fig. 1 is an equivalent schematic diagram of a three-dimensional omnidirectional wireless power transmission system of the present invention;
FIG. 2 is a schematic diagram of the three-phase coil synthesis vector generation of the present invention;
fig. 3 is a flow chart of the present invention.
Detailed Description
Example embodiments will now be described more fully with reference to the accompanying drawings. However, the exemplary embodiments may be embodied in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. The described features or characteristics may be combined in any suitable manner in one or more embodiments.
Based on the current amplitude modulation principle and the mathematical model of the omnidirectional WPT system, for the system structure of the three-phase orthogonal transmitting coil and one load coil, the maximum load power P can be obtained simultaneously when the magnetic vector angle and the physical angle of the load coil are completely equal out Maximum input power P in And a maximum transmission efficiency η. It is therefore only necessary to search for the maximum input power by current amplitude modulation at the transmitting end, so that both maximum load power and maximum transmission efficiency can be achieved.
From the electromagnetic induction theorem, the magnetic vector angle (θ and θ are the two-dimensional omnidirectional WPT system and θ are the three-dimensional omnidirectional WPT system)
Figure BDA0002998591280000071
) And the physical angle of the load coil (the two-dimensional omnidirectional WPT system is theta * The three-dimensional omnidirectional WPT system is theta * And->
Figure BDA0002998591280000072
) When the magnetic fluxes obtained by the load coils are the largest when the magnetic fluxes are completely equal, and the load coils can receive the maximum power at the moment. Therefore, the corresponding magnetic vector angle when the maximum load power is realized is the physical angle of the load coil. Therefore, an optimal step angle is obtained by a gradient descent method based on a Barzilai-Borwein method, and the magnetic vector angle is disturbed by the optimal step angle, so that the current injected into the three-phase orthogonal transmitting coil is changed, the input power of the omnirange WPT system after the current is disturbed is detected, and the corresponding magnetic field is obtained when the input power reaches the maximumVector angle (two-dimensional omnidirectional WPT system is θ, three-dimensional omnidirectional WPT system is θ and +.>
Figure BDA0002998591280000081
) I.e. the actual physical position of the load coil (two-dimensional omnidirectional WPT system is theta * The three-dimensional omnidirectional WPT system is theta * And->
Figure BDA0002998591280000082
)。
The present invention will be described in detail with reference to the accompanying drawings and the detailed description.
Firstly, establishing a mathematical model of an omnidirectional wireless power transmission system, and obtaining an objective function. A three-dimensional omni-directional wireless power transmission system is exemplified here, but the method is equally applicable to a two-dimensional omni-directional wireless power transmission system.
Fig. 1 is an equivalent schematic diagram of a three-dimensional omnidirectional wireless power transmission system consisting of three orthogonal transmit coils and one receive coil. Wherein V is dc And I dc Respectively a direct current power supply voltage and a direct current power supply current; q (Q) 1 -Q 12 Switching tubes for three groups of single-phase bridge type inversion currents; l (L) 1 、L 2 、L 3 The inductance of each phase of transmitting coil is respectively; c (C) 1 、C 2 、C 3 Compensation capacitors of the transmitting coils of each phase respectively; r is R 1 、R 2 、R 3 Parasitic resistances of the transmitting coils of the phases respectively; l (L) 4 An inductance for the receiving coil; c (C) 4 A compensation capacitance for the receiving coil; r is R 4 Parasitic resistance of the receiving coil; r is R L Is an equivalent load resistance; m is M n4 (n=1, 2, 3) represents mutual inductance of each phase transmitting coil and receiving coil; m is M 12 、M 23 、M 13 Representing mutual inductance between the transmitting coils of each phase; u (U) 1 、U 2 、U 3 Respectively representing the bridge port output voltage of each phase of inverter; i 1 、I 2 、I 3 Respectively representing the current flowing into each phase of transmitting coil; i 4 Indicating the current flowing into the receiving coil.
As shown in fig. 2, θ and
Figure BDA0002998591280000083
is the physical angle of the composite current vector on the three-dimensional plane, where θ is the current vector +.>
Figure BDA0002998591280000084
Forward included angle with Z axis, +.>
Figure BDA0002998591280000085
For current vector->
Figure BDA0002998591280000086
The projection on the XOY plane forms an included angle with the positive X axis; n is the iteration times of the gradient descent method; delta theta is the step length of theta in the gradient descent method; />
Figure BDA0002998591280000087
Is>
Figure BDA0002998591280000088
Is a step length of (2); alpha is the learning rate of the gradient descent method; θ (k) is the value of θ at time k; />
Figure BDA0002998591280000089
For time k->
Figure BDA0002998591280000091
Is a value of (2); θ (k-1) is the value of θ at time k-1; />
Figure BDA0002998591280000092
Time k-1
Figure BDA0002998591280000093
Is a value of (2); />
Figure BDA0002998591280000094
The value of the objective function at the current moment; />
Figure BDA0002998591280000095
Is->
Figure BDA0002998591280000096
Fixing, wherein theta is provided with a corresponding objective function value of delta theta; />
Figure BDA0002998591280000097
Is fixed by theta and is->
Figure BDA0002998591280000098
With increment->
Figure BDA0002998591280000099
Corresponding objective function values. />
Figure BDA00029985912800000910
Time k-1
Figure BDA00029985912800000911
Partial derivative with respect to θ; />
Figure BDA00029985912800000912
For time k-1->
Figure BDA00029985912800000913
About->
Figure BDA00029985912800000914
Is a partial derivative of (2); />
Figure BDA00029985912800000915
For time k->
Figure BDA00029985912800000916
Partial derivative with respect to θ; />
Figure BDA00029985912800000917
For time k->
Figure BDA00029985912800000918
About->
Figure BDA00029985912800000919
Is a partial derivative of (c).
For a single planar circular coil, the magnetic flux density at the center of the coil can be found by the Biot-Savart theorem
Figure BDA00029985912800000920
Is that
Figure BDA00029985912800000921
In the method, in the process of the invention,
Figure BDA00029985912800000922
and->
Figure BDA00029985912800000923
Tangential unit vectors and radial unit vectors of the planar circular coils respectively; r is the radius of the coil; mu (mu) 0 Is vacuum magnetic permeability; n (N) P Is the number of turns of the coil. From the right-hand screw rule, +.>
Figure BDA00029985912800000924
Perpendicular to the planar circular coil.
Similarly, the magnetic flux density at the center of the three-phase coil
Figure BDA00029985912800000925
Equal to the magnetic flux density of the center of the respective coil>
Figure BDA00029985912800000926
Vector sum of (i=1, 2, 3).
Figure BDA00029985912800000927
Wherein I is 1 、I 2 And I 3 Respectively representing the effective values of currents flowing into the three transmitting coils;
Figure BDA00029985912800000928
the unit vectors of the X axis, the Y axis and the Z axis are respectively shown.
Three transmitting coils are provided and are powered by an in-phase and same-frequency alternating current power supply,
Figure BDA00029985912800000929
and->
Figure BDA00029985912800000930
The current vectors flowing into the transmitting coils of the respective phases are shown separately. According to the current amplitude control principle, the effective value I of the current flowing into three transmitting coils 1 、I 2 And I 3 Respectively is
Figure BDA00029985912800000931
Wherein θ and
Figure BDA00029985912800000932
is the physical angle of the resultant current vector on the three-dimensional plane, as shown in FIG. 2, where θ is the resultant current vector +.>
Figure BDA00029985912800000933
Forward included angle with Z axis, +.>
Figure BDA00029985912800000934
For synthesizing current vector +.>
Figure BDA00029985912800000935
The projection in the XOY plane is at an angle to the positive X-axis. Three current vectors>
Figure BDA0002998591280000101
And->
Figure BDA0002998591280000102
A resultant current vector can be generated>
Figure BDA0002998591280000103
I is the resultant current vector->
Figure BDA0002998591280000104
Is a function of the magnitude of (a). From the above analysis, it is known that the magnetic flux density at the center of the three-phase coil +.>
Figure BDA0002998591280000105
And the combined current vector->
Figure BDA0002998591280000106
In the same direction, the magnitude is proportional to the amplitude I, thus by varying θ and +.>
Figure BDA0002998591280000107
Can change the magnetic flux density in the center of the three-phase coil>
Figure BDA0002998591280000108
And provides an omnidirectional magnetic field in three dimensions.
Is provided with
Figure BDA0002998591280000109
And->
Figure BDA00029985912800001010
Is 0. According to FIG. 1, the KVL equation can be listed as shown in equation (4)
Figure BDA00029985912800001011
In the method, in the process of the invention,
Figure BDA00029985912800001012
and->
Figure BDA00029985912800001013
And the output voltage vectors of the bridge ports of the inverters of the respective phases are respectively shown. Three transmit coils are orthogonal to each other, thus M 12 ＝M 13 ＝M 23 =0. Therefore, the formula (4) can be simplified into
Figure BDA00029985912800001014
Wherein X is 1 、X 2 、X 3 、X 4 Represented by formula (6).
Figure BDA00029985912800001015
The current vector flowing into the receiving coil can be calculated by the method (6)
Figure BDA00029985912800001016
Is that
Figure BDA00029985912800001017
Effective value I of current flowing into receiving coil 4 Is that
Figure BDA0002998591280000111
Equation (7) characterizes the current flowing into the receiving coil, from equation (7) the power P received by the load can be calculated load Is that
Figure BDA0002998591280000112
Also, the power P received by the receiving coil out Is that
Figure BDA0002998591280000113
Input power P of DC source in Loss P including inverter inv Ohm of transmitting coilLoss P loss Received power P of receiving coil out . The ohmic losses of the transmitting coil include the ohmic losses P of the transmitting coil 1 loss1 Ohmic loss P of transmitting coil 2 loss2 And ohmic loss P of transmitting coil 3 loss3 . The loss of the three-phase transmitting coil can be calculated by equation (11).
Figure BDA0002998591280000114
To simplify the analysis, the resistances of the three transmit coils are considered equal, satisfying the following equation:
R 1 ＝R 2 ＝R 3 ＝R (12)
thus, ohmic loss P of the transmitting coil can be calculated loss Is that
P loss ＝P loss1 +P loss2 +P loss3 ＝I 2 R (13)
Loss P of inverter inv Including the conduction loss and the switching loss of the power device, the loss P of the inverter can be calculated by the method (14) inv Is that
Figure BDA0002998591280000115
The combined formula (10), the formula (13) and the formula (14) can calculate the input power P of the direct current source in Is that
Figure BDA0002998591280000116
The transmission efficiency η can be calculated as
Figure BDA0002998591280000121
The input power P can be obtained by introducing variables K and gamma in Power P received by load load The expression of the transmission efficiency η is rewritten as
P load ＝I 2 R L Ksin 2 (θ+γ)
P in ＝P loss +P inv +I 2 (R 4 +R L )Ksin 2 (θ+γ) (17)
Figure BDA0002998591280000122
Wherein K and γ are represented by formula (18).
Figure BDA0002998591280000123
From equation (17), it can be seen that the conditions for achieving maximum load power, maximum input power, and maximum transmission efficiency are the same, and are only θ and
Figure BDA0002998591280000124
related to the following. The maximum input power can be realized, and the maximum load power and the maximum transmission efficiency can be realized at the same time, so that the power flow control can be realized only by inputting power information. Similarly, the transmitting end detects the input power, and when the input power is maximum, the corresponding theta * And->
Figure BDA0002998591280000125
I.e. the actual physical position of the load coil. The target equation is therefore the input power P in An expression.
From the formula (15), after the system is determined, P in The value of (2) depends only on θ and
Figure BDA0002998591280000126
the problem of the actual physical position detection of the load coil can thus be converted into a mathematical optimization problem, which can be described as:
Figure BDA0002998591280000127
when the system is in normal operation, the input power of the direct current source is required to be detected in real time, if the input power P is detected in Descent means that the position of the load coil changes and the position detection algorithm starts to be executed.
The following describes the solving of the mathematical optimization problem in steps using a gradient descent method based on the Barzilai-Borwein method.
Step 1: setting each initial parameter
Let θ sum
Figure BDA0002998591280000131
The initial values of (2) are all 0.Δθ and +.>
Figure BDA0002998591280000132
Should be small enough so that the WPT system does not produce a large buffeting around the optimization point. But at the same time Δθ and +>
Figure BDA0002998591280000133
But should also be large enough so that the sensor can detect the change. The invention suggests Δθ and +.>
Figure BDA0002998591280000134
The value is between 0.001rad and 0.005 rad.
θ and according to initialization
Figure BDA0002998591280000135
From equation (3), the given values of the three transmitting coil currents at the present time can be found, and current control is performed. After the current is stabilized, obtaining the input power P in an initial state according to the sampled direct current voltage and the sampled direct current in (0, 0), and will-P in (0, 0) is given to F (0, 0), and the process proceeds to step 2.
Step 2: calculating initial state information
The gradient descent method based on the Barzilai-Borwein method requires an additional calculation of a set of data, and thus requires calculation of information of an initial state.
1) Calculating the partial derivative of the initial state objective function with respect to θ
And calculating a given value of the current of the three-phase transmitting coil at the present moment according to the formula (20), and executing current control. After the current is stabilized, obtaining the input power P in an initial state according to the sampled direct current voltage and the sampled direct current in (Δθ, 0), and will be-P in (Δθ, 0) is given to F (Δθ, 0).
Figure BDA0002998591280000136
From equation (21), the partial derivative of the initial state objective function with respect to θ can be calculated
Figure BDA0002998591280000137
And assign it to
Figure BDA0002998591280000138
Figure BDA0002998591280000139
2) Calculating initial state objective function
Figure BDA00029985912800001310
Partial derivative of (2)
And calculating a given value of the current of the three-phase transmitting coil at the present moment according to the formula (22), and executing current control. After the current is stabilized, obtaining the input power in the initial state according to the sampled direct current voltage and direct current
Figure BDA0002998591280000141
And will be
Figure BDA0002998591280000142
Assign->
Figure BDA0002998591280000143
Figure BDA0002998591280000144
From equation (23), the initial state objective function is calculated
Figure BDA0002998591280000145
Partial derivative of>
Figure BDA0002998591280000146
And assign it +.>
Figure BDA0002998591280000147
Figure BDA0002998591280000148
3) Calculating the input power at the next moment
Figure BDA0002998591280000149
The given value of the current of each phase transmitting coil at the next time is calculated according to the formula (24), and current control is performed. After the current is stabilized, obtaining the input power at the next moment according to the sampled direct current voltage and direct current
Figure BDA00029985912800001410
And will->
Figure BDA00029985912800001411
Assign->
Figure BDA00029985912800001412
Figure BDA00029985912800001413
To this end, a first set of all data based on the Barzilai-Borwein method for optimal step size has been obtained. Next, the current time information is saved according to equation (25), where α takes a value of 0.5. And is combined withθ (k) sum of the current time
Figure BDA00029985912800001414
Assigning values to θ and +.>
Figure BDA00029985912800001415
Step 3 is entered.
Figure BDA00029985912800001416
Step 3: calculating the partial derivative of the objective function at time k with respect to θ
And calculating the given value of the current of each phase transmitting coil at the present moment according to the formula (26), and executing current control. After the current is stabilized, obtaining the input power at the moment k according to the sampled direct current voltage and direct current
Figure BDA00029985912800001417
And will be
Figure BDA00029985912800001418
Assign->
Figure BDA00029985912800001419
Figure BDA0002998591280000151
From equation (27), the partial derivative of the objective function at time k with respect to θ can be calculated
Figure BDA0002998591280000152
And assign it to
Figure BDA0002998591280000153
Step 4 is entered.
Figure BDA0002998591280000154
Step 4: calculating the relation of the objective function at the moment k
Figure BDA0002998591280000155
Partial derivative of (2)
And calculating the given value of the current of each phase transmitting coil at the present moment according to the formula (28), and executing current control. After the current is stabilized, obtaining the input power at the moment k according to the sampled direct current voltage and direct current
Figure BDA0002998591280000156
And will be
Figure BDA0002998591280000157
Assign->
Figure BDA0002998591280000158
Figure BDA0002998591280000159
From equation (29), the k-time objective function can be calculated
Figure BDA00029985912800001510
Partial derivative of>
Figure BDA00029985912800001511
And assign it +.>
Figure BDA00029985912800001512
Step 5 is entered.
Figure BDA00029985912800001513
Step 5: calculating an optimal step size
The gradient method searches along the steepest descent direction, and is opposite to the gradient direction of the objective function. As long as the current iteration point is not a stationary point, a continued decrease of the objective function can be ensured. The convergence speed of the algorithm and the accuracy of the final result are greatly dependent on the step length alpha, and the larger the step length alpha is, the faster the convergence speed of the gradient descent method is, but the larger the oscillation is near the optimal value. Conversely, when the step length alpha is smaller, the more the iteration times of the gradient descent method are, the slower the convergence speed is. Therefore, the accuracy and convergence speed of the algorithm need to be weighed when setting the step size α.
Different step size selections result in different gradient algorithms. In recent years, a lot of research has been conducted on the selection of the step size by the gradient method. The main idea of the Barzilai-Borwein method is to use the information in the previous iteration to decide the step size in the current iteration. For the two-dimensional convex function problem, a specific choice of step sizes is given and demonstrated to ensure their super-linear convergence.
Defining s according to Barzilai-Borwein method k 、z k
Figure BDA0002998591280000161
Wherein s is k The vector difference, denoted as search points at time k and time k-1; z k The gradient difference of the search point vector is expressed as k time and k-1 time; x is x k A vector denoted as search point at time k; x is x k-1 A vector denoted as the search point at time k-1;
Figure BDA0002998591280000162
a gradient denoted as a search point vector at time k; />
Figure BDA0002998591280000163
Denoted as the gradient of the search point vector at time k-1.
Therefore, the optimum step size α can be calculated from the equation (31), and the process proceeds to step 6.
Figure BDA0002998591280000164
Step 6: updating θ (k+1) sum
Figure BDA0002998591280000165
From the calculated optimal step alpha, the k+1 time θ (k+1) and the k+1 time θ can be calculated from the equation (32)
Figure BDA0002998591280000166
And proceeds to step 7.
Figure BDA0002998591280000167
Step 7: calculating the input power at time k+1
Figure BDA0002998591280000168
The θ (k+1) at time k+1 is added to
Figure BDA0002998591280000169
Assigning values to θ and +.>
Figure BDA00029985912800001610
And the current value of each transmitting coil is calculated according to the formula (3). After the current is stabilized, obtaining the input power at the moment k+1 according to the sampled direct current voltage and direct current
Figure BDA00029985912800001611
And will->
Figure BDA00029985912800001612
Assign->
Figure BDA00029985912800001613
Step 8 is entered.
Step 8: preserving k time information
Information at time k is stored according to equation (33). So far, one iteration of the gradient descent method based on the Barzilai-Borwein method is completed, the iteration number N is increased by 1, and the step 9 is entered to judge whether the iteration is completed or not.
Figure BDA0002998591280000171
Step 9: judging whether the iteration is finished
The maximum iteration number can be set, if the maximum iteration number or the objective function value calculated by two iterations is reached
Figure BDA0002998591280000172
Meets the error requirement, and outputs theta (k) and +.>
Figure BDA0002998591280000173
I.e. the actual physical position of the load coil. If neither condition is satisfied, θ (k) and +.>
Figure BDA0002998591280000174
Assigning values to θ and +.>
Figure BDA0002998591280000175
Returning to the step 3.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

Claims (1)

1. A method for detecting the position of a load coil in an omnidirectional wireless power transmission system, comprising the steps of:
s1: setting initial parameters
Establishing a mathematical model of an omnidirectional wireless power transmission system, and setting theta and theta
Figure FDA0004064820020000011
For the physical angle of the synthesized current vector on the three-dimensional plane, the input power P in the initial state is obtained according to the sampled direct current voltage and direct current in (0, 0), proceeding to step S2; wherein θ is the current vector +.>
Figure FDA0004064820020000012
Forward included angle with Z axis, +.>
Figure FDA0004064820020000013
For current vector->
Figure FDA0004064820020000014
The projection on the XOY plane forms an included angle with the positive X axis;
s2: calculating initial state information
Calculating information of an initial state based on a gradient descent method of a Barzilai-Borwein method;
s201: calculating the partial derivative of the initial state objective function;
calculating the given value of the current of the three-phase transmitting coil at the present moment according to the formula (20), performing current control, and obtaining the input power P in the initial state according to the sampled direct current voltage and the sampled direct current after the current is stabilized in (. DELTA.θ, 0), and P in (. DELTA.θ, 0) is given to F (DELTA.θ, 0);
Figure FDA0004064820020000015
wherein, delta theta is the step length of theta in the gradient descent method;
from equation (21), the partial derivative of the initial state objective function with respect to θ can be calculated
Figure FDA0004064820020000016
And assign it to
Figure FDA0004064820020000017
The I represents synthetic electricityStream vector->
Figure FDA0004064820020000018
The amplitude of said I 1 Representing the effective value of the current flowing into the transmitting coil 1, which acts on the Z-axis of the three-dimensional coordinate, said I 2 Representing the effective value of the current flowing into the transmitting coil 2, which acts on the Y-axis of the three-dimensional coordinates, said I 3 The effective value of the current flowing into the transmitting coil 3, which acts on the X-axis of the three-dimensional coordinates, is shown;
Figure FDA0004064820020000019
s202: calculating initial state objective function
Figure FDA00040648200200000110
Is a partial derivative of (2);
calculating a given value of the current of the three-phase transmitting coil at the present moment according to a formula (22), and executing current control; after the current is stabilized, obtaining the input power in the initial state according to the sampled direct current voltage and direct current
Figure FDA0004064820020000021
Figure FDA0004064820020000022
And will be
Figure FDA0004064820020000023
Assign->
Figure FDA0004064820020000024
Figure FDA0004064820020000025
Wherein, the said
Figure FDA0004064820020000026
Is>
Figure FDA0004064820020000027
Is a step length of (2);
from equation (23), the initial state objective function is calculated
Figure FDA0004064820020000028
Partial derivative of>
Figure FDA0004064820020000029
And assign it to
Figure FDA00040648200200000210
/>
Figure FDA00040648200200000211
S203: calculating the input power at the next moment
Figure FDA00040648200200000212
Calculating the given value of the current of each phase transmitting coil at the next moment according to the formula (24), and executing current control; after the current is stabilized, obtaining the input power at the next moment according to the sampled direct current voltage and direct current
Figure FDA00040648200200000213
Figure FDA00040648200200000214
And will be
Figure FDA00040648200200000215
Assign->
Figure FDA00040648200200000216
Figure FDA00040648200200000217
Then, the current time information is stored according to a formula (25), wherein alpha takes a value of 0.5, and theta (k) at the current time is added with
Figure FDA00040648200200000218
Assigning values to θ and +.>
Figure FDA00040648200200000219
Step S3 is entered;
Figure FDA00040648200200000220
s3: calculating the theta partial derivative of the objective function at the moment k;
calculating the given value of each phase transmitting coil current at the present moment, executing current control, and obtaining the input power at the k moment according to the sampled direct current voltage and direct current after the current is stabilized
Figure FDA00040648200200000221
Calculating partial derivative +.about theta of the objective function at k moment>
Figure FDA0004064820020000031
Calculating the given value of each phase transmitting coil current at the present moment according to the formula (26), performing current control, and obtaining the input power at the k moment according to the sampled direct current voltage and direct current after the current is stabilized
Figure FDA0004064820020000032
Figure FDA0004064820020000033
Calculating the partial derivative of the objective function at the moment k with respect to θ from the equation (27)
Figure FDA0004064820020000034
And assign it +.>
Figure FDA0004064820020000035
Step S4 is entered;
Figure FDA0004064820020000036
s4: calculating the relation of the objective function at the moment k
Figure FDA0004064820020000037
Partial derivative;
calculating the given value of the current of each phase transmitting coil at the present moment, and executing current control; after the current is stabilized, obtaining the input power at the moment k according to the sampled direct current voltage and direct current
Figure FDA0004064820020000038
Calculating the k moment objective function about +.>
Figure FDA0004064820020000039
Partial derivative of>
Figure FDA00040648200200000310
/>
Calculating the given value of the current of each phase transmitting coil at the present moment according to the formula (28), and executing current control; after the current is stabilized, obtaining the input power at the moment k according to the sampled direct current voltage and direct current
Figure FDA00040648200200000311
Figure FDA00040648200200000312
And will be
Figure FDA00040648200200000313
Assign->
Figure FDA00040648200200000314
Figure FDA00040648200200000315
Calculating the k moment objective function from the formula (29)
Figure FDA00040648200200000316
Partial derivative of>
Figure FDA00040648200200000317
Figure FDA00040648200200000318
S5: θ partial derivative sum based on k moment objective function
Figure FDA00040648200200000319
Calculating the optimal step length alpha by partial derivative;
definition of s according to the Barzilai-Borwein method k 、z k ：
Figure FDA0004064820020000041
Wherein s is k The vector difference, denoted as search points at time k and time k-1; z k The gradient difference of the search point vector is expressed as k time and k-1 time; x is x k Denoted as time-of-k searchVector of cable points; x is x k-1 A vector denoted as the search point at time k-1;
Figure FDA0004064820020000042
a gradient denoted as a search point vector at time k; />
Figure FDA0004064820020000043
A gradient denoted as a search point vector at time k-1;
calculating the optimal step length alpha according to the formula (31), and entering a step S6;
Figure FDA0004064820020000044
s6: according to the calculated optimal step length alpha, theta (k+1) and theta (alpha+1) at the moment of k+1 are obtained
Figure FDA0004064820020000045
From the calculated optimal step alpha, the k+1 time θ (k+1) and the k+1 time θ can be calculated from the equation (32)
Figure FDA0004064820020000046
And proceeds to step S7;
Figure FDA0004064820020000047
s7: the θ (k+1) at time k+1 is added to
Figure FDA0004064820020000048
Assigning values to θ and +.>
Figure FDA0004064820020000049
Calculating the current value of each current transmitting coil, and obtaining the input power +.1 of the moment k+ according to the sampled direct current voltage and direct current after the current is stable>
Figure FDA00040648200200000410
And will be
Figure FDA00040648200200000411
Assign->
Figure FDA00040648200200000412
S8: saving information at the moment k, completing one iteration based on a Barzilai-Borwein method gradient descent method, adding 1 to iteration times N, and entering a step 9;
storing information at the k moment according to a formula (33), completing one iteration of a gradient descent method based on a Barzilai-Borwein method, adding 1 to iteration times N, and entering a step S9;
Figure FDA0004064820020000051
s9: if the maximum iteration number or the objective function value calculated by two iterations is reached
Figure FDA0004064820020000052
If the set error requirement is met, ending the iteration and outputting theta (k) and +.>
Figure FDA0004064820020000053
The actual physical position of the load coil; if none of them meets the setting error requirement, θ (k) and +.>
Figure FDA0004064820020000054
Assigning values to θ and +.>
Figure FDA0004064820020000055
And returning to the step S3./>
CN202110344895.0A 2021-03-30 2021-03-30 Load coil position detection method for omnidirectional wireless power transmission system Active CN112968535B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110344895.0A CN112968535B (en) 2021-03-30 2021-03-30 Load coil position detection method for omnidirectional wireless power transmission system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110344895.0A CN112968535B (en) 2021-03-30 2021-03-30 Load coil position detection method for omnidirectional wireless power transmission system

Publications (2)

Publication Number Publication Date
CN112968535A CN112968535A (en) 2021-06-15
CN112968535B true CN112968535B (en) 2023-05-16

Family

ID=76281440

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110344895.0A Active CN112968535B (en) 2021-03-30 2021-03-30 Load coil position detection method for omnidirectional wireless power transmission system

Country Status (1)

Country Link
CN (1) CN112968535B (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114220489B (en) * 2021-12-15 2022-12-02 北京应用物理与计算数学研究所 Non-monotonic line search method and device for atomic structure relaxation
CN114285184B (en) * 2021-12-30 2024-05-03 河北工业大学 Self-adaptive omnidirectional mobile phone wireless charging device and control system

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108695992A (en) * 2018-04-13 2018-10-23 中南大学 The real-time maximum power transfer method of 3-D wireless electric energy transmission system
CN109462293A (en) * 2018-09-27 2019-03-12 深圳市华禹无线供电技术有限公司 A kind of receiving coil location determining method of omnidirection radio energy transmission system
CN110971009A (en) * 2019-10-17 2020-04-07 上海电机学院 Control method of wireless power transmission system
CN111064239A (en) * 2019-11-01 2020-04-24 东南大学 Load positioning and power constant control method for three-dimensional wireless charging system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108695992A (en) * 2018-04-13 2018-10-23 中南大学 The real-time maximum power transfer method of 3-D wireless electric energy transmission system
CN109462293A (en) * 2018-09-27 2019-03-12 深圳市华禹无线供电技术有限公司 A kind of receiving coil location determining method of omnidirection radio energy transmission system
CN110971009A (en) * 2019-10-17 2020-04-07 上海电机学院 Control method of wireless power transmission system
CN111064239A (en) * 2019-11-01 2020-04-24 东南大学 Load positioning and power constant control method for three-dimensional wireless charging system

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
DE类RFPA激励的四线圈磁耦合共振无线输电电路研究;王之轩;《中国优秀硕士学位论文》;20210115;全文 *
Incorporating the Barzilai-Borwein Adaptive Step Size into Sugradient Methods for Deep Network Training;Antonio Robles-Kelly;《2019 Digital Image Computing: Techniques and Applications (DICTA)》;20200102;全文 *
Variable frequency triple‑phase‑shift modulation strategy for minimizing RMS current in dual‑active‑bridge DC‑DC converters;Xiangdong Sun;《Journal of Power Electronics》;20210107;全文 *
基于时频变换实现矩形大定源瞬变电磁数据三维频率域反演;李大俊;《中国博士学位论文全文》;20170915;全文 *

Also Published As

Publication number Publication date
CN112968535A (en) 2021-06-15

Similar Documents

Publication Publication Date Title
CN112968535B (en) Load coil position detection method for omnidirectional wireless power transmission system
Zhang et al. Omnidirectional and efficient wireless power transfer system for logistic robots
CN108778821A (en) Method and apparatus for positioning vehicle
CN111313790A (en) Apparatus for controlling charging system using motor driving system
CN110929448B (en) Simulation analysis method for no-load current consistency of permanent magnet synchronous motor
CN107623388A (en) Wireless power transmission method and system
CN108736588A (en) Detection method, system, device and the readable storage medium storing program for executing of coil position relationship
CN112018903A (en) Three-phase cylindrical curved surface coil and full-space wireless power transmission system based on same
CN104272578A (en) Methods and systems for controlling a multiphase electromagnetic machine
CN111342729B (en) Self-adaptive reverse thrust control method of permanent magnet synchronous motor based on gray wolf optimization
KR20180118498A (en) 2d circular-array structure wireless power transfer method and apparatus
CN106026417A (en) Multiphase excitation-total space pickup wireless energy transfer system and control method therefor
US11502555B2 (en) System and method for wireless power transmission
Jiang et al. Multi-parameter identification of permanent magnet synchronous motor based on improved grey wolf optimization algorithm
CN108306566A (en) Line inductance electromotor secondary flux linkage estimation method based on extended state observer
CN108695992B (en) Real-time maximum power transmission method of three-dimensional wireless electric energy transmission system
Lin et al. Design of bidirectional power converters coupled with coils for wireless charging of AUV docking systems
CN116722772A (en) Permanent magnet synchronous motor control method and system based on improved particle swarm
Dorjsuren et al. Three-axis dynamic modeling of induction motor
Tang et al. A real-time tracking algorithm for 3D wireless maximum power transfer to a moving device
CN113612321B (en) Wireless charging control method and wireless charging transmitting device
Wang et al. Research on the Control Strategy of Communication-Free IPT System Based on Multi-Parameter Joint Real-Time Identification
Zhu et al. A 3D wireless charging cube with externally enhanced magnetic field for extended range of wireless power transfer
CN111523256A (en) Mutual inductance calculation method of coaxial multi-coil related to non-ferromagnetic metal medium
CN114640188A (en) Load stable power control method for omni-directional wireless power transmission system

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant