CN110611375A - A multi-frequency and multi-load wireless power supply system based on the principle of PT symmetry - Google Patents

Abstract

The invention discloses a multi-frequency multi-load wireless power supply system based on the principle of PT symmetry, comprising n transmitting devices, n receiving devices and n loads, where n is a natural number greater than or equal to 2; each transmitting device consists of a series The connected negative resistance, the transmitting coil, the resonant capacitor at the transmitting end and the equivalent internal resistance of the transmitting coil, the negative resistance provides energy for the system, and the transmitting coils of the n transmitting devices are decoupled from each other or are in a weakly coupled state; each receiving device Both are composed of receiving coils connected in series, resonant capacitance at the receiving end and equivalent internal resistance of the receiving coil, and one load is connected in series with one receiving device, and the receiving coils of n receiving devices are decoupled from each other or in a weakly coupled state. The invention utilizes the principle of PT symmetry to realize power distribution and control among multiple loads, and adopts multi-frequency transmission to solve the influence of cross-coupling between coils on the system, so as to realize stable and efficient provision of constant power for multiple loads at the same time. In application, it has obvious advantages.

Description

A multi-frequency multi-load wireless power supply system based on PT symmetry principle

technical field

The present invention relates to the technical field of wireless energy transmission or wireless power transmission, in particular to a multi-frequency and multi-load wireless power supply system based on the principle of PT symmetry.

Background technique

As is known in the industry, Wireless Power Transfer (WPT), compared with the traditional wire power supply method without electrical connection, has the advantages of flexibility, convenience, safety and reliability. Existing wireless power transmission technology is mainly based on the principles of electromagnetic induction and magnetic resonance, and some research results have been applied to electronic consumer products, implanted medical equipment, electric vehicle charging and other fields. With the development of wireless power transmission technology, there are more and more demands for multi-load wireless power supply systems, but the power distribution and control between loads, as well as the cross-coupling between transmitting coils and receiving coils, have always been constraints for multi-loads. The main bottleneck problem in the development of wireless power supply system.

In recent years, researchers have applied parity-time (PT) symmetric quantum theory to the field of wireless power transmission, which has shown great advantages and achieved constant output power and transmission efficiency. However, the traditional wireless power supply system based on the principle of PT symmetry is very sensitive to cross-coupling between coils.

Contents of the invention

The purpose of the present invention is to overcome the disadvantages and deficiencies of the prior art, and propose a multi-frequency multi-load wireless power supply system based on the principle of PT symmetry. Transmission solves the influence of cross-coupling between coils on the system, and realizes that it can provide constant power for multiple loads simultaneously, stably and efficiently, and has significant advantages in practical applications.

In order to achieve the above object, the technical solution provided by the present invention is: a multi-frequency multi-load wireless power supply system based on the principle of PT symmetry, the system includes n transmitting devices, n receiving devices and n loads, where n is greater than Or a natural number equal to 2; each transmitting device is composed of a negative resistance connected in series, a transmitting coil, a transmitting terminal resonant capacitor and an equivalent internal resistance of the transmitting coil, wherein the negative resistance provides energy for the system, and the transmitting coils of n transmitting devices Each receiving device is composed of a receiving coil connected in series, a resonant capacitor at the receiving end and an equivalent internal resistance of the receiving coil, and one receiving device is connected in series with one load, and the receiving devices of n receiving devices The coils are decoupled from each other or in a weakly coupled state.

Further, the natural frequencies of the n transmitting devices are different from each other, and at the same time, the natural frequency of the i-th transmitting device is the same as that of the i-th receiving device, i=1, 2, 3...n, which satisfies:

ω _t1 ＝ω _r1 ≠ω _t2 ＝ω _r2 ≠...ω _tn ＝ω _rn

In the formula, the natural frequency of the i-th transmitting device is expressed as The natural frequency of the i-th receiving device is expressed as L _ti is the inductance value of the i-th transmitting coil, L _ri is the inductance value of the i-th receiving coil; C _ti is the resonant capacitance value of the i-th transmitting end, C _ri is the resonant capacitance value of the i-th receiving end, i= 1,2,3...n.

Further, when the system runs stably, it needs to satisfy the parity-time symmetry condition:

In the formula, R _ti and R _ri are the equivalent internal resistance values of the i-th transmitting and receiving coils respectively; -R _Ni is the value of the i-th negative resistance; -R _Li is the value of the i-th load; is the coupling coefficient between the i-th transmitting coil and the i-th receiving coil, M _tiri is the mutual inductance value between the i-th transmitting coil and the i-th receiving coil, L _ti is the inductance value of the i-th transmitting coil, L _ri is the inductance value of the i-th receiving coil.

Further, the voltage and current relationship of the negative resistance satisfies: V _ti =-R _Ni I _ti , and the phase relationship satisfies: Among them, I _ti is the current flowing through the i-th negative resistance, V _ti is the voltage across the i-th negative resistance, -R _Ni is the resistance value of the i-th negative resistance, and it is automatically adjustable.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. It realizes the stable and efficient provision of constant power for multiple loads at the same time, and solves the problem of power distribution and control among multiple loads.

2. Solve the adverse effects of cross-coupling between coils on the system.

Description of drawings

Fig. 1 is a schematic diagram of an equivalent circuit of a multi-frequency multi-load wireless power supply system based on the principle of PT symmetry.

Fig. 2 is a schematic structural diagram of two completely decoupled transmitting coils in an embodiment.

Fig. 3 is a relationship curve between system transmission efficiency and coupling coefficient in an embodiment.

Fig. 4 is a relationship curve between the obtained power and the coupling coefficient of each load in the embodiment.

Detailed ways

In order to further illustrate the content and characteristics of the present invention, the specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, but the implementation and protection of the present invention are not limited thereto.

As shown in Figure 1, the multi-frequency multi-load wireless power supply system based on the principle of PT symmetry provided by this embodiment includes n transmitting devices, n receiving devices and n loads R _Li , n is a natural number greater than or equal to 2 ;Each transmitting device is composed of negative resistance-R _Ni , transmitting coil L _ti , transmitting terminal resonant capacitor C _ti and equivalent internal resistance R _ti of transmitting coil connected in series, i=1,2,3...n, wherein, Negative resistance-R _Ni provides energy for the system, and the transmitting coils of n transmitting devices are decoupled from each other or are in a weakly coupled state; each receiving device is composed of a receiving coil L _ri connected in series, a receiving end resonance capacitor C _ri and a receiving The equivalent internal resistance R _ri of the coil is composed, and a load R _Li is connected in series with a receiving device, and the receiving coils of the n receiving devices are decoupled from each other or are in a weakly coupled state.

It is assumed that the natural frequencies of the n transmitting devices are different from each other, and the natural frequency of the i-th transmitting device is the same as that of the i-th receiving device. At this time, the coupling between the i-th transmitting coil and the j-th receiving coil has negligible influence on the system, where i=1,2,3...n, j=1,2,3...n, and i≠ j. Therefore, the i-th transmitting device and the i-th receiving device can work stably independently of other coils. The following takes the i-th transmitting device and the i-th receiving device as examples to analyze the system. According to Figure 1, the Kiel Hough's law can be obtained:

In formula (1), -R _Ni is the i-th negative resistance value, R _Li is the i-th load resistance value; ω is the operating frequency of the system, Indicates the natural frequency of the i-th transmitter, Indicates the natural frequency of the i-th receiving device, L _ti is the inductance value of the i-th transmitting coil, L _ri is the inductance value of the i-th receiving coil; C _ti is the resonant capacitance value of the i-th transmitting end, C _ri is the The resonant capacitance value of the i receiving end, R _ti and R _ri are the equivalent internal resistance values of the i-th transmitting and receiving coils respectively, are the current vectors of the i-th transmitter and receiver, respectively, is the coupling coefficient between the i-th transmitting coil and the i-th receiving coil, and M _tiri is the mutual inductance value between the i-th transmitting coil and the i-th receiving coil.

The condition for formula (1) to have a non-zero solution is:

Separating the real and imaginary parts of formula (2) can get:

When the i-th transmitter and the i-th receiver form a parity-time symmetric circuit, that is

Then formula (3) can be simplified as:

From the above formula, the frequency solution can be obtained as:

From formula (6), it can be further obtained that the condition for the pure real part of the frequency to exist is:

Therefore, the system needs to meet the following conditions when it works in a steady state:

At this time, from formula (1) and formula (4), the ratio of current effective value I _ti of the i-th transmitting device to current effective value I _ri of the i-th receiving device can be obtained as:

At this moment, the transmission efficiency η _tiri of the i-th transmitting device and the i-th receiving device is equal to:

The power P _oi of the i-th load is equal to:

In the formula, V _ti and V _ri are respectively the i-th negative resistance and the voltage across the i-th load.

In order to further illustrate the advantages of the present invention, in this embodiment, a dual-frequency dual-load wireless power transmission system based on the principle of PT symmetry is designed. The electrical parameters of the system are as follows: the inductance of the first transmitting coil L _t1 = 200 μH, the inductance of the second transmitting coil L _t2 = 200 μH, the inductance of the first receiving coil L _r1 = 200 μH, the inductance of the second receiving coil L _r2 = 200 μH, Natural frequency ω _t1 ＝ω _r1 ＝300kHz, ω _t2 ＝ω _r2 ＝200kHz, equivalent internal resistance R _t1 ＝R _t2 ＝R _r1 ＝R _r2 ＝0.1Ω, ignoring the coupling between transmitting coils and receiving coils, Negative resistance is realized by power electronic circuits.

Optionally, Figure 2 shows a structure of two transmitting coils that are decoupled from each other, which is realized by stacking DD coils and rectangular coils of the same size facing each other. On the one hand, the decoupling between the coils is realized, and on the other On the one hand, the installation space is saved, but the transmitting coil is not limited to the above structure.

Figure 3 and Figure 4 are the relationship curves of the system transmission efficiency obtained by simulation and the output power obtained by each load and the coupling coefficient when the load R _L1 =10Ω, R _L2 =5Ω, it can be seen from the figure that the system proposed by the present invention works in space In the said-time symmetric region, the output power and transmission efficiency of each load are not affected by the cross-coupling between the transmitting coil and the receiving coil, and can provide constant power for multiple loads stably and efficiently at the same time.

The embodiments described above are only preferred embodiments of the present invention. The present invention provides a multi-frequency and multi-load wireless power supply system based on the principle of PT symmetry. The present invention and its embodiments should not be limited thereto. The changes made in the shape and principle should all be covered within the protection scope of the present invention.

Claims (4)

1. A multi-frequency multi-load wireless power supply system based on the principle of PT symmetry, characterized in that: the system includes n transmitting devices, n receiving devices and n loads, n is a natural number greater than or equal to 2; each The transmitting devices are composed of a negative resistance connected in series, a transmitting coil, a resonant capacitor at the transmitting end, and an equivalent internal resistance of the transmitting coil. Coupling state; each receiving device is composed of a receiving coil connected in series, a resonant capacitor at the receiving end, and an equivalent internal resistance of the receiving coil, and one receiving device is connected in series with a load, and the receiving coils of n receiving devices are decoupled from each other or in a state of Weakly coupled state. 2. A multi-frequency multi-load wireless power supply system based on the principle of PT symmetry according to claim 1, characterized in that: the natural frequencies of the n transmitting devices are different from each other, while the natural frequency of the i-th transmitting device It is the same as the natural frequency of the i-th receiving device, i=1, 2, 3...n, which satisfies: ω _t1 ＝ω _r1 ≠ω _t2 ＝ω _r2 ≠...ω _tn ＝ω _rn In the formula, the natural frequency of the i-th transmitting device is expressed as The natural frequency of the i-th receiving device is expressed as L _ti is the inductance value of the i-th transmitting coil, L _ri is the inductance value of the i-th receiving coil; C _ti is the resonant capacitance value of the i-th transmitting end, C _ri is the resonant capacitance value of the i-th receiving end, i= 1,2,3...n. 3. A multi-frequency and multi-load wireless power supply system based on the principle of PT symmetry according to claim 1, characterized in that: when the system runs stably, it needs to satisfy the parity-time symmetry condition: In the formula, R _ti and R _ri are the equivalent internal resistance values of the i-th transmitting and receiving coils respectively; -R _Ni is the value of the i-th negative resistance; -R _Li is the value of the i-th load; is the coupling coefficient between the i-th transmitting coil and the i-th receiving coil, M _tiri is the mutual inductance value between the i-th transmitting coil and the i-th receiving coil, L _ti is the inductance value of the i-th transmitting coil, L _ri is the inductance value of the i-th receiving coil. 4. A multi-frequency multi-load wireless power supply system based on PT symmetry principle according to claim 1, characterized in that: the voltage and current relationship of the negative resistance satisfies: V _ti =-R _Ni I _ti , phase relationship Satisfy: Among them, I _ti is the current flowing through the i-th negative resistance, V _ti is the voltage across the i-th negative resistance, -R _Ni is the resistance value of the i-th negative resistance, and it is automatically adjustable.