CN110649715A - Multi-frequency many-to-one wireless power supply system based on PT (potential Transformer) symmetry principle - Google Patents

Abstract

The invention discloses a multi-frequency many-to-one wireless power supply system based on the principle of PT symmetry, comprising a transmitting device and a receiving device; the transmitting device includes one negative resistance and n transmitting modules, and the receiving device includes n receiving modules and one Load; n transmitter modules are connected in parallel with the negative resistance, each transmitter module is composed of a transmitter coil connected in series, a transmitter resonance capacitor and an equivalent internal resistance of the transmitter coil; n receiver modules are connected in parallel with the load, each receiver module They are all composed of a receiving coil connected in series, a resonant capacitor at the receiving end and an equivalent internal resistance of the receiving coil. The invention is based on the PT symmetry principle, adopts multi-frequency transmission, solves the instability problem caused by the cross-coupling between the transmitting coil and the receiving coil, and realizes the constant output power and transmission when the load moves between the transmitting modules. efficiency, effectively improving the anti-offset capability of the system, and the launch module has the characteristics of no-load self-protection.

Description

A multi-frequency many-to-one wireless power supply system based on the principle of PT symmetry

technical field

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

Background technique

As is known in the industry, the Wireless Power Transfer (WPT) technology has the advantages of flexibility, convenience, safety and reliability compared with the traditional wire power supply method without electrical connection. The 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, implantable medical equipment, electric vehicle charging and other fields. However, the existing wireless power supply system based on magnetic coupling needs to align the transmitting coil and the receiving coil during operation. Once the deviation occurs, the transmission efficiency and output power of the system will drop sharply, and the user experience will be greatly reduced.

In recent years, researchers have applied parity-time (PT) symmetry quantum theory to the field of wireless energy transmission, showing great advantages, achieving constant output power and transmission efficiency, but the traditional single-transmission based on the PT symmetry principle The coil wireless power supply system can only work in the PT symmetrical area, and the anti-offset ability is still limited. The use of multiple transmitting coils will help to expand the PT symmetrical area and further strengthen the system's anti-offset ability, but the cross between no-load and coils Coupling is an urgent problem to be solved in multi-transmit coil systems.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art, and proposes a multi-frequency many-to-one wireless power supply system based on the PT symmetry principle. On the one hand, the PT symmetry principle is used to achieve constant transmission efficiency and output power, and on the other hand Multi-frequency transmission is adopted to solve the problem of cross-coupling between no-load and coils in a multi-transmitting coil system, effectively improving the stability and anti-offset capability of the system. At the same time, the transmitting module has no-load self-protection characteristics. In practical applications, it has significant advantage.

In order to achieve the above purpose, the technical solution provided by the present invention is: a multi-frequency many-to-one wireless power supply system based on the PT symmetry principle, including a transmitter and a receiver; the transmitter includes a negative resistance and n transmitters. module, the receiving device includes n receiving modules and 1 load, where n is a natural number greater than or equal to 2; n transmitting modules are connected in parallel with the negative resistance, and each transmitting module is connected in series by a transmitting coil, a transmitting terminal The resonant capacitor is composed of the equivalent internal resistance of the transmitting coil. The transmitting coils of the n transmitting modules are in a decoupled or weakly coupled state with each other; the n receiving modules are connected in parallel with the load, and each receiving module is composed of a series-connected receiving coil, The receiving end resonant capacitance is composed of the equivalent internal resistance of the receiving coil, and the receiving coils of the n receiving modules are in a decoupled or weakly coupled state with each other.

Further, the natural frequencies of the n transmitter modules are different from each other, and the natural frequency of the i-th transmitter module is the same as the natural frequency of the i-th receiver module, i=1, 2, 3...n, which satisfies:

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

第i个接收模块的固有频率表示为

L_ti为第i个发射线圈的电感值，L_ri为第i个接收线圈的电感值；C_ti为第i个发射端谐振电容值，C_ri为第i个接收端谐振电容值。In the formula, the natural frequency of the i-th transmitting module is expressed as

The natural frequency of the i-th receiver module is expressed as

L _ti is the inductance value of the ith transmitting coil, L _ri is the inductance value of the ith receiving coil; C _ti is the resonant capacitance value of the ith transmitting end, and C _ri is the resonant capacitance value of the ith receiving end.

Further, the negative resistance is composed of a connected AC controlled voltage source and a control module; the control module includes a drive control signal generation module, a drive control signal switching module and a switch drive module that are connected in sequence; the drive control signal generation module It includes n current sampling modules and n phase control modules for generating n-way drive control signals, wherein the i-th drive control signal is generated by the i-th current sampling module and the i-th phase control module, i=1, 2,3...n, the input end of the ith current sampling module is connected with the ith transmitting module, the output end of the ith current sampling module is connected with the input end of the ith phase control module, the The i-th current sampling module samples the loop current of the i-th transmitting module, and generates the i-th drive control signal through the i-th phase control module. or the same-phase square wave; the output ends of the n phase control modules are connected to the input end of the drive control signal switching module, and each drive control signal is input to the drive control signal switching module, and the drive control signal switching module At the same time, only one drive control signal is output to the switch drive module, wherein the drive control signal in the same direction or in the opposite direction to the loop current of the jth transmitter module is selected according to the load position, j=1, 2, 3...n. In the current load position of j transmitter modules, compared with the coupling degree between other transmitter modules and receiver modules with the same natural frequency, the coupling degree between the jth transmitter module and the jth receiver module is the largest. The j transmitter modules and the jth receiver module must satisfy the parity-time symmetry condition:

表示第j个发射模块的固有频率，

表示第j个接收模块的固有频率，R_tj、R_rj分别为第j个发射、接收线圈的等效内阻值，-R_N为负电阻的值，-R_L负载的值，

为第j个发射线圈和第j个接收线圈之间的耦合系数，M_tjrj为第j个发射线圈与第j个接收线圈之间的互感值，L_tj为第j个发射线圈的电感值，L_rj为第j个接收线圈的电感值；所述开关驱动模块产生开关器件的驱动信号至交流受控电压源。In the formula,

represents the natural frequency of the jth transmitting module,

Represents the natural frequency of the jth receiving module, R _tj and R _rj are the equivalent internal resistance values of the jth transmitting and receiving coils respectively, -R _N is the value of the negative resistance, -R _L is the value of the load,

is the coupling coefficient between the jth transmitting coil and the jth receiving coil, M _tjrj is the mutual inductance value between the jth transmitting coil and the jth receiving coil, L _tj is the inductance value of the jth transmitting coil, L _rj is the inductance value of the j-th receiving coil; the switch driving module generates the driving signal of the switching device to the AC controlled voltage source.

其中，I_ti为流过负电阻的电流，V_ti为负电阻两端的电压，-R_N为负电阻的阻值，且自动可调。Further, the voltage and current relationship of the negative resistance satisfies: V _ti =-R _N I _ti , and the phase relationship satisfies:

Among them, I _ti is the current flowing through the negative resistance, V _ti is the voltage across the negative resistance, -R _N is the resistance value of the negative resistance, and is automatically adjustable.

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

1. It can provide constant output power and transmission efficiency for the load in a large range, and effectively improve the anti-offset capability of the wireless power supply system based on the PT symmetry principle.

2. Solve the problem of cross-coupling between no-load and coils of multi-transmitting coil system.

Description of drawings

FIG. 1 is a structural block diagram of a multi-frequency many-to-one wireless power supply system based on the PT symmetry principle.

FIG. 2 is an equivalent schematic diagram of a multi-frequency many-to-one wireless power supply system based on the PT symmetry principle.

FIG. 3 is a schematic structural diagram of two fully decoupled transmitting coils in an embodiment.

FIG. 4 is a schematic structural diagram of two fully decoupled receiving coils in an embodiment.

FIG. 5 shows the loop current waveforms of each transmitter module and each receiver module when the load is above the first transmitter coil in the embodiment.

FIG. 6 shows the loop current waveforms of each transmitter module and each receiver module when the load is between the first transmitter coil and the second transmitter coil in the embodiment.

FIG. 7 shows the loop current waveforms of each transmitter module and each receiver module when the load is above the second transmitter coil in the embodiment.

Detailed ways

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

As shown in FIG. 1, the multi-frequency many-to-one wireless power supply system based on the PT symmetry principle provided in this embodiment includes a transmitting device and a receiving device; the transmitting device includes a negative resistance 101 and n transmitting modules 102, The receiving device includes n receiving modules 103 and 1 load _RL , where n is a natural number greater than or equal to 2; n transmitting modules 102 are connected in parallel with the negative resistance 101, The coil L _ti , the resonant capacitance C _ti of the transmitting end and the equivalent internal resistance R _ti of the transmitting coil are composed of (i=1, 2, 3...n), and the transmitting coils L _ti of the n transmitting modules 102 are decoupled or weak from each other. Coupling state; n receiving modules 103 are connected in parallel with the load _RL , and each receiving module 103 is composed of a series-connected receiving coil L _ri , a resonant capacitor C _ri at the receiving end, and an equivalent internal resistance R _ri of the receiving coil (i=1 , 2, 3...n), the receiving coils L _ri of the n receiving modules 103 are in a decoupled or weakly coupled state with each other.

The negative resistance 101 is composed of a connected AC controlled voltage source 101-1 and a control module 101-2, wherein the control module 101-2 includes a drive control signal generation module 101-21 connected in sequence, a drive control signal switch module 101-22 and switch driving module 101-23, the driving control signal generating module 101-21 includes n current sampling modules 101-211 and n phase control modules 101-212, and generates n driving control signals, wherein, The ith drive control signal is generated by the ith current sampling module 101-211 and the ith phase control module 101-212, and the input end of the ith current sampling module 101-211 is connected to the ith transmission module 102, The output terminal of the i-th current sampling module 101-211 is connected to the input terminal of the i-th phase control module 101-212. Specifically, the i-th current sampling module 101-211 samples the loop current of the i-th transmitting module 102. The phase control modules 101-212 generate the i-th drive control signal, and the i-th drive control signal is a square wave (i=1, 2, 3... n); the output terminals of the n phase control modules 101-212 are connected to the input terminals of the driving control signal switching module 101-22 after being connected, and each drive control signal is input to the driving control signal switching module 101-22; the driving The control signal switching module 101-22 outputs only one driving control signal to the switch driving module 101-23 at the same time, and the switch driving module 101-23 generates the driving signal of the switching device to the AC controlled voltage source 101-1.

It is set that the natural frequency of the ith transmitting module is the same as the natural frequency of the ith receiving module, and the natural frequencies of the n transmitting modules are different from each other. At this time, the influence of the coupling between the ith transmitting coil and the jth receiving coil on the system can be ignored, where i=1, 2, 3...n, j=1, 2, 3...n, and i≠ j. Therefore, the i-th transmitter module and the i-th receiver module can work stably independently of other coils. Figure 2 is the equivalent circuit diagram of the i-th transmitter module and the i-th receiver module. According to Figure 2, Kirkho husband's law can be obtained:

表示第i个发射模块的固有频率，表示第i个接收模块的固有频率，L_ti为第i个发射线圈的电感值，L_ri为第i个接收线圈的电感值；C_ti为第i个发射端谐振电容值，C_ri为第i个接收端谐振电容值，R_ti、R_ri分别为第i个发射、接收线圈的等效内阻值，分别为第i个发射模块和接收模块回路电流向量，

为第i个发射线圈和第i个接收线圈之间的耦合系数，M_tiri为第i个发射线圈与第i个接收线圈之间的互感值。In formula (1), -R _N is the negative resistance value, R _L is the load resistance value; ω is the operating frequency of the system,

represents the natural frequency of the i-th transmitter module, Indicates the natural frequency of the ith receiving module, L _ti is the inductance value of the ith transmitting coil, L _ri is the inductance value of the ith receiving coil; C _ti is the resonant capacitance value of the ith transmitting end, and C _ri is the ith Resonant capacitance values of i receivers, R _ti and R _ri are the equivalent internal resistance values of the i-th transmitting and receiving coils, respectively, are the loop current vectors of the i-th transmitter module and receiver module, respectively,

is the coupling coefficient between the ith transmitting coil and the ith receiving coil, and M _tiri is the mutual inductance value between the ith transmitting coil and the ith 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 ith transmitting module and the ith receiving module form a parity-time symmetric circuit, that is,

The formula (3) can be simplified as:

The frequency solution can be obtained from the above formula as:

From equation (6), it can be further obtained that the conditions for the existence of a pure real part solution for the frequency are:

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 the ith transmitting module current RMS I _ti to the ith receiving module current RMS value I _ri can be obtained as:

At this time, the transmission efficiency η of the system is equal to:

The output power P _o of the system is equal to:

where V _in and V _o are the voltages across the negative resistance and the load resistance, respectively.

In order to further illustrate the advantages of the present invention, in this embodiment, a dual-frequency dual-to-one wireless power transmission system based on the PT symmetry principle is designed.

The electrical parameters of the system are as follows: the first transmitting coil inductance L _t1 = 100 μH, the second transmitting coil inductance L _t2 = 100 μH, the first receiving coil inductance L _r1 = 100 μH, the second receiving coil inductance L _r2 = 100 μH, Natural frequency ω _t1 =ω _r1 =355kHz,ω _t2 =ω _r2 =177kHz, equivalent internal resistance R _t1 =R _t2 =R _r1 =R _r2 =0.1Ω, ignoring the coupling between the transmitting coils and between the receiving coils, Negative resistance is implemented by power electronic circuits.

Optionally, in this example, the transmitting coil structure is shown in Figure 3, which is a mutually decoupled transmitting coil structure, which is realized by arranging DD-type coils and rectangular coils of the same size side by side. The coil is a DD type coil, and the second transmitting coil is a rectangular coil, but the transmitting coil is not limited to the above structure.

Optionally, in this example, the receiving coil structure is shown in FIG. 4 , which is a mutually decoupled receiving coil structure, which is realized by stacking DD coils and rectangular coils of the same size in front of each other. Specifically, The first receiving coil is a DD coil, and the second receiving coil is a rectangular coil. On the one hand, the decoupling between the receiving coils is realized, and on the other hand, the installation space is saved, but the receiving coil is not limited to the above structure.

Preferably, in this example, the transmitting coils are arranged horizontally side by side, and the receiving coils move horizontally directly above the transmitting coils, which realizes decoupling between different types of transmitting coils and receiving coils. Decoupling between DD-type transmitter coils, decoupling between DD-type receiver coils and rectangular transmitter coils.

Figure 5, Figure 6 and Figure 7 show the waveforms of the loop current of each transmitter module and each receiver module loop current obtained by simulation when the load is at different positions when the load is _RL = 10Ω. When moving upward, the output power and transmission efficiency of the load are basically unchanged, and are not affected by the change of the coupling coefficient between the transmitting coil and the receiving coil and the cross-coupling. Loaded with self-protection features.

The above-mentioned embodiments are only preferred embodiments of the present invention. The present invention provides a multi-frequency, many-to-one wireless power supply system based on the principle of PT symmetry. The present invention and its embodiments should not be limited to this. Changes made to the shape and principle of the invention should all be covered within the protection scope of the present invention.

Claims (4)

1. A multi-frequency many-to-one wireless power supply system based on PT symmetrical principle is characterized in that: comprises a transmitting device and a receiving device; the transmitting device comprises 1 negative resistor and n transmitting modules, the receiving device comprises n receiving modules and 1 load, wherein n is a natural number greater than or equal to 2; the n transmitting modules are connected with the negative resistor in parallel, each transmitting module consists of a transmitting coil, a transmitting end resonant capacitor and a transmitting coil equivalent internal resistance which are connected in series, and the transmitting coils of the n transmitting modules are in a decoupling or weak coupling state; the n receiving modules are connected with the load in parallel, each receiving module consists of a receiving coil, a receiving end resonant capacitor and a receiving coil equivalent internal resistance which are connected in series, and the receiving coils of the n receiving modules are in a decoupling or weak coupling state.

2. A multi-frequency many-to-one wireless power supply system based on PT symmetry principle as claimed in claim 1, wherein: the natural frequencies of the n transmitting modules are different from each other, while the natural frequency of the ith transmitting module is the same as the natural frequency of the ith receiving module, i is 1,2,3 … n, that is to say, the natural frequencies of the n transmitting modules are different from each other, namely, the natural frequencies of the ith transmitting module and the ith receiving module satisfy:

ω_t1＝ω_r1≠ω_t2＝ω_r2≠…ω_tn＝ω_rn

wherein the natural frequency of the i-th transmitting module is represented as

The natural frequency of the i-th receiving module is expressed as

L_tiIs the inductance value of the i-th transmitting coil, L_riThe inductance value of the ith receiving coil; c_tiIs the ith transmitting end resonance capacitance value, C_riIs the ith receiving end resonance capacitance value.

3. A multi-frequency many-to-one wireless power supply system based on PT symmetry principle as claimed in claim 1, wherein: the negative resistor consists of an alternating current controlled voltage source and a control module which are connected; the control module comprises a drive control signal generation module, a drive control signal switching module and a switch drive module which are sequentially connected; the driving control signal generating module comprises n current sampling modules and n phase control modules and is used for generating n paths of driving control signals, wherein the ith path of driving control signals is generated by the ith current sampling module and the ith phase control module, i is 1,2 and 3 … n, the input end of the ith current sampling module is connected with the ith transmitting module, the output end of the ith current sampling module is connected with the input end of the ith phase control module, the ith current sampling module samples loop current of the ith transmitting module and generates the ith path of driving control signals through the ith phase control module, and the ith path of driving control signals are square waves which are completely opposite in phase or in phase with the loop current of the ith transmitting module; the output ends of the n phase control modules are connected and then connected with the input end of the drive control signal switching module, each path of drive control signal is input to the drive control signal switching module, the drive control signal switching module only outputs one path of drive control signal to the switch drive module at the same time, wherein, the drive control signal which is in the same direction or opposite direction with the loop current of the jth transmitting module is selected according to the load position, j is 1,2,3 … n, the coupling degree between the jth transmitting module and the jth receiving module is the maximum compared with the coupling degree between the transmitting module and the receiving module with the same inherent frequency under the current load position, and the jth transmitting module and the jth receiving module need to meet the space scale-time symmetry condition:

in the formula (I), the compound is shown in the specification,

the natural frequency of the jth transmit module is indicated,

denotes the natural frequency, R, of the jth receiving module_tj、R_rjEquivalent internal resistance values of jth transmitting and receiving coils, -R_NIs the value of a negative resistance, -R_LThe value of the load is such that,

for the coupling coefficient between the jth transmitting coil and the jth receiving coil, M_tjrjIs the mutual inductance value between the jth transmitting coil and the jth receiving coil, L_tjInductance of jth transmitting coilValue, L_rjThe inductance value of the jth receiving coil; the switch driving module generates a driving signal of the switching device to an alternating current controlled voltage source.

4. The system according to claim 1, wherein the system comprises: the voltage and current relation of the negative resistance satisfies the following conditions: v_ti＝-R_NI_tiThe phase relation satisfies:

wherein, I_tiFor the current flowing through the negative resistance, V_tiIs the voltage across the negative resistance, -R_NIs the resistance value of the negative resistance and is automatically adjustable.

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