CN107919739B - Transmission power frequency selection method of wireless electric energy transmission system - Google Patents
Transmission power frequency selection method of wireless electric energy transmission system Download PDFInfo
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- CN107919739B CN107919739B CN201711127219.8A CN201711127219A CN107919739B CN 107919739 B CN107919739 B CN 107919739B CN 201711127219 A CN201711127219 A CN 201711127219A CN 107919739 B CN107919739 B CN 107919739B
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- 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
- H02J50/10—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling
- H02J50/12—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling of the resonant type
Abstract
A transmission power frequency selection method of a wireless electric energy transmission system belongs to the field of transmission power frequency selection of the wireless electric energy transmission system, and the wireless electric energy transmission system comprises a frequency-adjustable power source, a transmitting coil circuit, a receiving coil circuit, a load, a coupling coefficient detection device and a frequency adjustment controller; the transmission power frequency selection method is to determine an actual load, and the system obtains a coupling coefficient k between a transmitting coil and a receiving coil through a coupling coefficient detection device and feeds the coupling coefficient k back to a frequency adjustment controller; and the frequency regulation controller determines the working frequency of the power source according to the magnitude relation between the coupling coefficient k and k1 and k2 under the actual load condition, so that the maximum transmission power of the wireless power transmission system is realized.
Description
Technical Field
The invention relates to a transmission power frequency selection method of a wireless electric energy transmission system, in particular to a maximum transmission power frequency selection method of a magnetic coupling resonant wireless electric energy transmission system.
Background
The wireless power transmission technology is an energy transmission mode without direct electrical contact from a power supply to an electric load by means of energy transfer media in physical spaces such as an electromagnetic field and microwaves, and has the advantages of safety, reliability, convenience and the like compared with the traditional wired power supply mode.
The magnetic coupling resonance type wireless power transmission system is a multi-parameter mutually cross-coupled nonlinear system, the change of working frequency has a large influence on the transmission power of the system, and in order to realize maximum power output, a system power source is enabled to work at the resonance frequency so as to ensure the resonance state of the system. Under the resonance state, the transmission power of the magnetic coupling resonance type wireless power transmission system is greatly influenced by the change of the load and the coupling coefficient, and the frequency splitting phenomenon also occurs in the system when the coupling coefficient is overlarge.
Aiming at the non-resonant state and the frequency splitting phenomenon, control methods such as impedance matching, frequency tracking and the like are mostly adopted at present, and the relation between the transmission power and the coupling coefficient and the working frequency when a specific load is analyzed and verified in the literature of maximum power efficiency point analysis and experimental verification of a magnetic coupling resonant wireless power transmission system. However, for loads of different sizes, there is no literature to analyze the relationship between the operating frequency and the coupling coefficient k when the transmission power is maximum, especially when the actual load is less than the critical load. Therefore, the transmission power frequency selection method of the wireless electric energy transmission system can achieve maximum power output within the full load range of the system according to the relation between the working frequency and the coupling coefficient.
Disclosure of Invention
The invention aims to provide a transmission power frequency selection method of a magnetic coupling resonant wireless power transmission system, which is used for adjusting the working frequency of a system power source to enable the transmission power to reach the maximum through a frequency adjustment controller when a coupling coefficient detection device detects that the coupling coefficient k between a transmitting coil and a receiving coil changes aiming at system loads with different sizes.
The invention is realized by the following technical scheme.
A transmission power frequency selection method of a wireless electric energy transmission system comprises a frequency-adjustable power source, a transmitting coil circuit, a receiving coil circuit, a load, a coupling coefficient detection device and a frequency adjustment controller. The method is characterized in that the critical load value of the wireless power transmission system can be determined according to the internal resistance parameter of the power source, the circuit parameter of the transmitting coil and the circuit parameter of the receiving coil; the magnitude relation between the actual load value and the critical load value determines the magnitude relation between the coupling coefficient k1 when the transmission power of the system is maximum under the self-resonant frequency and the coupling coefficient k2 when the frequency of the system is split; after the actual load is determined, the system obtains a coupling coefficient k between the transmitting coil and the receiving coil through the coupling coefficient detection device and feeds the coupling coefficient k back to the frequency adjustment controller; and the frequency adjustment controller determines the working frequency selection of the power source according to the magnitude relation between the coupling coefficient k and k1 and k2 under the actual load condition, so that the maximum transmission power of the wireless power transmission system is realized.
Further, the wireless power transmission system is realized in a magnetic coupling resonance mode.
Further, the transmit coil circuit and the receive coil circuit are series resonant circuits consisting of litz wire wound solenoid and CBB81 capacitor.
Furthermore, the receiving coil circuit obtains the transmission distance between the transmitting coil and the receiving coil through the distance measuring sensor and sends the transmission distance to the coupling coefficient detection device, and the coupling coefficient detection device converts the received transmission distance into a corresponding coupling coefficient k and feeds the coupling coefficient k back to the frequency adjustment controller.
Further, the frequency regulation controller is divided into a working mode 1 and a working mode 2 according to the system load, and after the working mode is determined, the frequency regulation controller is used for determining the relation between the working frequency and the coupling coefficient
The frequency adjustment of the power source is realized through DSP programming.
The invention realizes the working frequency control of the wireless electric energy transmission system, solves the frequency selection problem of the maximum transmission power in the full load range of the system and ensures the maximum power output of the wireless electric energy transmission system when the transmission distance is changed.
Drawings
FIG. 1 is a schematic diagram of the system architecture of the present invention.
Fig. 2 is an equivalent circuit model of the magnetic coupling resonant wireless power transmission system of the present invention.
FIG. 3 shows the coupling coefficient of the magnetic coupling resonant wireless power transmission system according to the present invention at the maximum transmission power at the self-resonant frequencyk 1And the coupling coefficient when frequency splitting occurs in the systemk 2And a loadR LThe change rule of (2).
Fig. 4 shows the variation of the output power with the coupling coefficient k at the resonance frequency point and the self-resonance frequency of the system when RL is 5 Ω.
Fig. 5 shows the variation of the output power of the system with the coupling coefficient k at different resonant frequencies when RL is 5 Ω.
Fig. 6 shows the variation of the output power with the coupling coefficient k at the resonance frequency point and the self-resonance frequency of the system when RL is 9.3275 Ω.
Fig. 7 shows the variation of the output power of the system with the coupling coefficient k at different resonant frequencies when RL is 9.3275 Ω.
Fig. 8 shows the variation of the output power with the coupling coefficient k at the resonance frequency point and the self-resonance frequency of the system when RL is 15 Ω.
Fig. 9 shows the variation of the output power of the system with the coupling coefficient k at different resonant frequencies when RL is 15 Ω.
Detailed Description
The following further describes the embodiments of the present invention with reference to the drawings.
As shown in fig. 1, a system structure diagram for implementing the technical scheme of the invention is shown. Comprises a frequency-adjustable power source 10, a transmitting coil circuit 20, a receiving coil circuit 30, a load 40, a coupling coefficient detection device 50 and a frequency adjustment controller 60. Fig. 2 is an equivalent circuit model of a magnetic coupling resonant wireless power transmission system. In the drawingsU S、R SThe output voltage and the internal resistance of the frequency-adjustable power source;L 1、C 1、R 1the coil inductance, the compensation capacitance and the coil equivalent resistance of the transmitting coil circuit;L 2、C 2、R 2the coil inductance, the compensation capacitance and the coil equivalent resistance of the receiving coil circuit;R Lis a load;Mis the mutual inductance between the transmitter coil and the receiver coil and
whereinkIs a coupling coefficient corresponding to a transmission distance between the transmission coils;Z inis the input impedance of the frequency adjustable power source. The maximum transmission power frequency selection method of the present invention is described below by taking the equivalent circuit model as an example.
The parameters of each part in the equivalent circuit model of fig. 2 are, respectively, the power source output voltage: US = 50V; internal resistance of a power source: RS =10 Ω; coil inductance L1= L2= L =83.3 uH; compensation capacitance C1= C2= C =10.1 nF; coil equivalent resistance R1= R2= R =0.35 Ω.
Input impedance of magnetic coupling resonant wireless power transmission system
Wherein:
when the circuit parameters of the transmitting coil and the receiving coil are consistent, the real part and the imaginary part of the input impedance of the power source are respectively as follows:
the magnetic coupling resonance type wireless power transmission system meets the condition that the maximum transmission power is met under the condition of different coupling coefficients and works in a resonance state, namely Im(Z in)=0。
From Im(Z in) =0 can obtain three angular frequencies that satisfy the condition that the system operates in the resonance state:
(3)
correspondingly, by
The available system has three resonance frequency pointsf 1 、f 2 、f 3. Whereinf 1Only the transmission coil parameters are relevant, called the self-resonance frequency point of the system.f 2 、f 3In order to split the frequency points, the frequency points are,
it can be known that the resonant frequencyf 2 、f 3Is about the coupling coefficientkAs a function of。
When the system works at the self-resonant frequency point
Condition R of the theorem of transmission by maximum powere(Z in)=R SThe coupling coefficient of the maximum transmission power of the system at the self-resonant frequency can be obtainedk 1，
Namely:
byω 2=ω 3Deducing the coupling coefficient when the system has frequency splittingk 2，
FIG. 3 shows the coupling coefficient of the maximum transmission power at the self-resonant frequency of the systemk 1And the coupling coefficient when frequency splitting occurs in the systemk 2There are three different magnitude relationships as the load varies.
Byk 1＝k 2The critical load value can be obtainedR L0＝B－RWherein:
(7)
critical load value obtained according to the above system parametersR L0＝9.3275Ω。
As can be seen in fig. 3: when in useR L＜R L0Coupling coefficient of maximum transmission power at self-resonant frequency of time systemk 1And the coupling coefficient when frequency splitting occurs in the systemk 2In a relationship ofk 1＞k 2. The relationship between the transmission power at the system self-resonant frequency and the variation of the system resonant frequency point with respect to the coupling coefficient is shown in fig. 4. As can be seen from FIG. 5, when the coupling coefficient is highk 2≤k＜k 3In spite of the frequency splitting phenomenon, the system is still at the self-resonant frequency pointf 1Has the largest transmission power. Wherein the coupling coefficientk 3Splitting frequency off 2 、f 3And self-resonant frequencyf 1While maximizing the transmission power of the system, an
. Therefore, whenk≤k 3While the system is operating at self-resonant frequencyf 1The maximum transmission power; when in usek>k 3Then the system will be at the split frequency pointf 2 、f 3Has the largest transmission power. And is composed of
It can be seen that the coupling coefficient is dependent onkChange of (3), splitting frequency pointsf 2 、f 3Will change continuously, and the maximum transmission power of the system will remain unchanged.
As can be seen from fig. 3R L＝R L0Coupling coefficient of maximum transmission power at self-resonant frequency of time systemk 1And the coupling coefficient when frequency splitting occurs in the systemk 2In a relationship ofk 1＝k 2. The relationship between the transmission power at the system self-resonant frequency and the variation of the system resonant frequency point with respect to the coupling coefficient is shown in fig. 6. It can be seen from FIG. 7 that the coupling coefficient isk≤k 1＝k 2While the system is operating at self-resonant frequencyf 1The maximum transmission power; when in usek＞k 1＝k 2At the split frequency pointf 2 、f 3Has the largest transmission power. And is composed of
It can be seen that the coupling coefficient is dependent onkChange of (3), splitting frequency pointsf 2 、 f 3Will change continuously, and the maximum transmission power of the system will remain unchanged.
As can be seen from fig. 3R L＞R L0Coupling coefficient of maximum transmission power at self-resonant frequency of time systemk 1And the coupling coefficient when frequency splitting occurs in the systemk 2In a relationship ofk 1＜k 2. The relationship between the transmission power at the system self-resonant frequency and the variation of the system resonant frequency point with respect to the coupling coefficient is shown in fig. 8. As can be seen from FIG. 9, when the coupling coefficient is largek≤k 2While the system is working at the self-resonant frequency pointf 1The maximum transmission power; when in usek＞k 2At the split frequency pointf 2 、f 3Has the largest transmission power. And is composed of
It can be seen that the coupling coefficient is dependent onkChange of (3), splitting frequency pointsf 2 、f 3Will change continuously, and the maximum transmission power of the system will remain unchanged.
From the above conclusions, it can be seen that: when the output power is maximum, the working frequency and coupling coefficient of the systemkThe relationship of (A) can be divided into two cases according to the load sizeR L＜R L0、R L≥R L0. Therefore, the frequency adjustment controller is adjusted according to the coupling coefficient between the transmission coilskThe modes of adjusting the operating frequency of the power source are called an operating mode 1 and an operating mode 2 respectively.
In specific implementation, firstly, determining the working mode of a frequency regulation controller according to the magnitude relation between the critical load value and the actual load of a system; then, the coupling coefficient is detected by the coupling coefficient detecting meanskFeeding back to the frequency adjustment controller; finally, the frequency adjustment controller is based on the coupling coefficientkAnd the relation with the working frequency adjusts the frequency of the power source, thereby ensuring that the output power reaches the maximum.
The analysis and simulation results show that the invention can realize that the wireless power transmission system can achieve maximum power output in the full load range, and is suitable for analyzing the wireless power transmission system with the constantly changing transmission distance.
Claims (5)
1. A transmission power frequency selection method of a wireless electric energy transmission system is characterized in that: the wireless electric energy transmission system comprises a frequency-adjustable power source, a transmitting coil circuit, a receiving coil circuit, a load, a coupling coefficient detection device and a frequency adjustment controller; the transmission power frequency selection method is to determine a critical load value of the wireless power transmission system according to an internal resistance parameter of a power source, a circuit parameter of a transmitting coil and a circuit parameter of a receiving coil, and the specific transmission power frequency selection method comprises the following steps:
first, the actual load is determined: the system obtains a coupling coefficient k between the transmitting coil and the receiving coil through the coupling coefficient detection device and feeds the coupling coefficient k back to the frequency adjustment controller; and the frequency adjustment controller determines the working frequency of the power source according to the magnitude relation between the coupling coefficient k and the coupling coefficient k1 when the transmission power of the system is maximum under the self-resonant frequency under the actual load condition and the coupling coefficient k2 when the frequency of the system is split, so that the maximum transmission power of the wireless power transmission system is realized.
2. The transmission power frequency selecting method of a wireless power transmission system according to claim 1, wherein: the wireless power transmission system is realized in a magnetic coupling resonance mode.
3. The transmission power frequency selecting method of a wireless power transmission system according to claim 1, wherein: the transmit coil circuit and receive coil circuit are series resonant circuits consisting of litz wire wound solenoid and CBB81 capacitor.
4. The transmission power frequency selecting method of a wireless power transmission system according to claim 1, wherein: the circuit of the receiving coil obtains the transmission distance between the transmitting coil and the receiving coil through the distance measuring sensor and sends the transmission distance to the coupling coefficient detection device, and the coupling coefficient detection device converts the received transmission distance into a corresponding coupling coefficient k and feeds the coupling coefficient k back to the frequency adjustment controller.
5. The transmission power frequency selecting method of a wireless power transmission system according to claim 1, wherein: the frequency regulation controller is divided into a working mode 1 and a working mode 2 according to the system load, and after the working mode is determined, the frequency regulation controller realizes the frequency regulation of the power source through DSP programming according to the relation between the working frequency and the coupling coefficient.
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| CN101273665A (en) * | 2005-09-07 | 2008-09-24 | 弗兰斯海默尔机械工程公司 | Circuit, shrink fixing and regulation method |
| CN105765839A (en) * | 2013-09-12 | 2016-07-13 | 奥克兰联合服务有限公司 | Resonant power supply with self tuning |
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| CN101273665A (en) * | 2005-09-07 | 2008-09-24 | 弗兰斯海默尔机械工程公司 | Circuit, shrink fixing and regulation method |
| CN105765839A (en) * | 2013-09-12 | 2016-07-13 | 奥克兰联合服务有限公司 | Resonant power supply with self tuning |
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| Yameng Wang;Jiancheng Song;Lingyan Lin;Xinghua Wu;.Parameters calculation and simulation of magnetic coupling resonance wireless power transfer system.《2016 Asia-Pacific International Symposium on Electromagnetic Compatibility (APEMC)》.2016, * |
| 变线圈结构的磁耦合谐振式无线电能传输系统;王亚檬 等；;《工矿自动化》;20170930;第43卷(第9期);第89-95页 * |
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