CN109921523B - Magnetic resonance wireless energy transfer system based on SS topology - Google Patents

Abstract

The present invention proposes a wireless energy transmission system based on SS topology, which is used to solve the technical problems of low efficiency and complex system when the load is large in the prior art, including an input module composed of a mains input module and a DC_DC step-down module. Power supply module, primary inverter module, primary impedance matching module, WPT module, secondary impedance matching module and secondary rectification filter module, by designing the primary and secondary coils in the WPT module, the wires are helically wound in two openings of U. The structure at the bottom of the magnetic core is designed, and the secondary impedance matching module is designed to match the output impedance of the WPT module to the optimal load point, which improves the transmission efficiency of the system. In addition, the primary impedance matching module is designed to improve the output impedance of the primary inverter module, so that DC_DC The input power supply module composed of the step-down module and the mains input module can be applied to replace the complex DC regulated power supply or the switching power supply module with transformer, which simplifies the system.

Description

Magnetic resonance wireless energy transfer system based on SS topology

technical field

The invention belongs to the technical field of wireless energy transmission, and relates to a magnetic resonance wireless energy transmission system, in particular to a magnetic resonance wireless energy transmission system based on SS topology, which is used for wireless power supply of larger loads.

Background technique

Wireless power transmission (Wireless Power Transmission, WPT) technology has always been a hot topic of human research. Compared with wired energy transmission, it avoids unsafe power supply factors such as sparks, bare wires, and wear during the process of obtaining energy through wire connections between electrical equipment. The emergence of wireless energy transmission technology has opened up new power supply channels for some special occasions: for example, the power supply of sealed environments, rotating parts, underwater monitoring, etc. Applications in consumer electronics and sensor networks.

The wireless energy transmission system is mainly divided into three types: radio wave radiation type, inductive coupling type and magnetic resonance type. Among them, the magnetic resonance type mainly uses the magnetic resonance of two coils in the near field of the electromagnetic field to realize the wireless energy of electric energy-magnetic energy-electrical energy. transmission. Compared with the radio wave radiation wireless energy transmission system, the wireless energy transmission system has the characteristics of large transmission power, high transmission efficiency and no directionality, and the transmission power has been increased from the previous milliwatt level to the kilowatt level, and the transmission efficiency has also been greatly improved. Compared with the inductively coupled wireless energy transmission system, the transmission distance is greatly improved, breaking through the limitation that the wireless transmission distance of the inductively coupled wireless energy transmission system is only within the millimeter level.

The existing common magnetic resonance wireless energy transmission system is mainly composed of an input power module, a primary inverter module, a WPT module and a secondary rectification filter module. The system transmission efficiency and complexity are important indicators to measure the quality of a system. The WPT module adopts the most basic double-coil structure, which can be divided into series-series (SS) according to the different connection methods of the primary transmitting coil and the secondary receiving coil with their primary resonance compensation capacitor and secondary resonance compensation capacitor respectively. topology, series-parallel (SP) topology, parallel-series (PS) topology, parallel-parallel (PP) topology. Among them, the SS topology has good characteristics such as its primary reflection impedance is independent of the load and suitable for small load systems, and has been widely studied and applied. For example, the application publication number is CN 107681791 A, the patent application titled "a half-bridge resonant wireless energy transmission system" discloses a half-bridge resonant wireless energy transmission system, including a DC power supply, a buck circuit, a half-bridge inverter A circuit, a first resonator, a second resonator and an auxiliary circuit, the invention mainly realizes the maintenance of the system resonance state through the control of the buck circuit and the auxiliary circuit, so as to achieve more efficient power transmission. However, the coils in the first resonator and the second resonator have simple structures, and the second resonator is directly connected to the load, resulting in a limited improvement in the wireless energy transmission efficiency between the two coils.

In addition, for the SS topology, due to its own characteristics, for larger loads, the corresponding primary reflected impedance is very small, which means that it only needs a small supply voltage under a certain power output, and the DC voltage is stabilized. The power supply is bulky, and it is not easy to integrate and commercialize the wireless energy system. However, if you design a wireless energy transmission system from the access to the mains, the pre-stage also needs to design a more complex switching power supply module with a transformer as the input power supply module. meet the application. To sum up, in view of the large load situation, how to consider the optimization from each part of the wireless energy transmission system, and design a complete high-efficiency and simple SS topology magnetic resonance wireless energy transmission system starting from the access to the mains is: A problem to be solved.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the above-mentioned defects in the prior art, and propose a magnetic resonance wireless energy transmission system based on SS topology, which is used to solve the technology of low efficiency and complex system when the load is large in the prior art question.

In order to achieve the above purpose, the technical solution adopted in the present invention includes an input power supply module 1, a primary inverter module 2, a WPT module 3 and a secondary rectification filter module 4 connected in sequence, wherein:

The input power supply module 1 is used to convert the input AC mains into adjustable DC output;

The primary inverter module 2 is used to convert the input DC voltage into a high-frequency AC voltage output, including a first switch MOS transistor S ₁ and a second switch MOS transistor S ₂ , the drain terminal of S ₂ and the source of S ₁ The extremes are connected, and the source is grounded;

The WPT module 3 is used to realize wireless energy transmission of electrical energy-magnetic energy-electrical energy, and includes the primary transmitting coil L _p and its primary resonance compensation capacitor C _p connected in series with each other, and the secondary receiving coil L _s and its secondary receiving coils connected in series with each other. a resonance compensation capacitor C _s , and the primary transmitting coil L _p and its primary resonance compensation capacitor C _p connected in series with each other are arranged relatively to the secondary receiving coil L _s and its secondary resonance compensation capacitor C _s connected in series;

The secondary rectification filter module 4 is used to convert the input high-frequency alternating current into a smooth and stable direct current output, and includes a rectifier bridge composed of four Schottky or fast recovery diodes, and is connected to one end of the output of the rectifier bridge. The first filter capacitor _CL , the first filter capacitor _CL and the other end of the output of the rectifier bridge are grounded;

The input power module 1 includes a mains input module 11 and a DC_DC step-down module 12. The mains input module 11 is used to convert the input AC mains into a smooth and stable DC output, including one end connected to each other and the other. A power frequency rectifier bridge with one end grounded and a second filter capacitor C; the DC_DC step-down module 12 is used to realize the adjustable step-down output of the DC power output by the input power module 11, including a high-voltage power MOS transistor S _b , a fast recovery diode D _b , inductance L _b and a third filter capacitor C _b ; the drain terminal of the high-voltage power MOS transistor S _b is connected to the ungrounded end of the second filter capacitor C ; the cathode of the fast recovery diode D _b is connected to S b The source terminal of _b is connected to and the anode is grounded; one end of the inductor L _b is connected to the cathode of the fast recovery diode D _b , and the other end is connected to the third filter capacitor C _b and the drain of the first switch MOS transistor S ₁ The extremes are connected, and the other end of the third filter capacitor C _b is grounded;

A primary impedance matching module 5 is connected between the primary inverter module 2 and the WPT module 3, and the primary impedance matching module 5 is used to improve the output port impedance of the primary inverter module 2, including a first matching Inductance L _f , first matching capacitor C _f , second matching inductance L _m2 and second matching capacitor C _m2 ; one end of the first matching inductance L _f is connected to the source terminal of the first switch MOS transistor S ₁ and the second matching capacitor C m2 ; The drain terminals of the _two switch MOS transistors S2 are connected, and the other end is connected to one end of the first matching capacitor C _f ; one end of the second matching capacitor C _m2 is connected to the other end of the first matching capacitor C _f and all One end of the second matching inductance L _m2 is connected, the other end of the C _m2 is grounded, and the other end of the second matching inductance L _m2 is connected to one end of the primary resonance compensation capacitor C _p ;

A secondary impedance matching module 6 is connected between the WPT module 3 and the secondary rectification and filtering module 4, and the secondary impedance matching module 6 is used to match the output port impedance of the WPT module 3 to its optimum. The load point includes a third matching inductor L _m1 and a third matching capacitor C _{m1 connected to one end of L m1 ;} both ends of the third matching capacitor C _m1 are connected to the input end of the rectifier bridge in the secondary rectification filter module connected, the other end of the third matching inductor L _m1 is connected to one end of the secondary resonance compensation capacitor C _s ;

In the WPT module 3, the primary transmitting coil L _s includes a primary U-shaped magnetic core and a wire spirally wound at the bottom of the primary U-shaped magnetic core, and the secondary receiving coil _Lp includes a secondary U-shaped magnetic core and a helical winding The wire at the bottom of the secondary U-shaped core, and the openings of the primary and secondary U-shaped cores are opposite.

In the above magnetic resonance wireless energy transmission system based on SS topology, the first matching inductance L _f and the first matching capacitor C _f , as well as the second matching inductance L _m2 and the second matching capacitor C _m2 respectively satisfy the following conditions:

Among them, ω=2πf, f is the resonant frequency of the WPT module, R is the equivalent port impedance of the output end of the primary impedance matching module, R _e2 is the target matching equivalent impedance, and R=R _e2 , R _ep is the WPT module to be matched Equivalent port impedance at the input.

In the above magnetic resonance wireless energy transmission system based on SS topology, the third matching inductance L _m1 and the third matching capacitor C _m1 satisfy the following conditions:

Where f is the resonant frequency of the WPT module, R _opt is the optimal target matching equivalent impedance, and _Re is the equivalent port impedance of the input end of the secondary rectifier filter module to be matched.

In the above magnetic resonance wireless energy transmission system based on SS topology, the wire spirally wound at the bottom of the primary U-shaped magnetic core and the wire spirally wound at the bottom of the secondary U-shaped magnetic core are single-strand copper wires or multi-strand Litz wires.

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

1. In the WPT module of the present invention, the openings of the primary U-shaped magnetic core and the secondary U-shaped magnetic core spirally wound with wires are opposite to each other, which optimizes the magnetic coupling path between the coils, increases the mutual inductance between the coils, and improves the WPT. At the same time, the output impedance of the WPT module is matched with the optimal load point through the secondary impedance matching module, so that the output impedance of the WPT module just corresponds to the output of its maximum efficiency. Compared with the existing technology, the system efficiency is effectively improved. .

2. The present invention improves the output impedance of the primary inverter module through the primary impedance matching module, so that the required power supply voltage under the same power level is increased, so that the input and output voltage difference of the DC_DC module can be maintained in a reasonable range, which is in the market. On the basis of the electrical input module, the DC_DC step-down module is connected as the input power supply, which avoids the defects of complex structure caused by the use of a DC regulated power supply or a switching power supply module with a transformer when the electrical load is large in the prior art, and it is easy to realize the system. integrated.

Description of drawings

Fig. 1 is the overall structure schematic diagram of the present invention;

Fig. 2 is the principle circuit diagram of the primary impedance matching module of the present invention;

3 is a schematic structural diagram of the primary coil and the secondary coil in the WPT module of the present invention;

Fig. 4 is the equivalent principle circuit diagram of the WPT module adopting SS topology of the present invention;

5 is a schematic circuit diagram of a secondary impedance matching module of the present invention;

6 is a schematic diagram of a comparison simulation result between the present invention and the average power of the input and output ports of the WPT module when the secondary impedance matching module is not added;

7 is a schematic diagram of a comparison simulation result between the present invention and the power supply voltage at the input end of the primary inverter module when the primary impedance matching module is not added;

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment, the present invention is described in further detail:

1, the present invention includes an input power module 1, a primary inverter module 2, a primary impedance matching module 5, a WPT module 3, a secondary impedance matching module 6, and a secondary rectification filter module 4 connected in sequence, wherein:

The input power module includes a commercial power input module 11 and a DC_DC step-down module 12. The commercial power input module 11 includes a second filter capacitor C connected to a power frequency rectifier bridge at one end and grounded at the other end; the power frequency rectifier The bridge converts the input AC mains power of 220V/50Hz into DC power with large pulsating components. After filtering by the second filter capacitor, the pulsating components are greatly eliminated, and the smooth and stable output is 308V±10% high-voltage DC power , and input to the DC_DC step-down module 12 connected to it. The DC_DC step-down module 12 includes a high voltage power MOS transistor S _b , a fast recovery diode D _b , an inductance L _b and a third filter capacitor C _b ; the drain terminal of the high voltage power MOS transistor S _b and the second filter capacitor The ungrounded end of C is connected to the ground; the cathode of the fast recovery diode D _b is connected to the source terminal of S _b and the anode is grounded; one end of the inductor L _b is connected to the cathode of the fast recovery diode D _b , and the other end is connected to the The third filter capacitor C _b is connected to the ground, and the other end of the third filter capacitor C _b is grounded; the DC_DC step-down module 12 inputs a high-frequency pulse signal with a certain duty ratio to the gate terminal of the high-voltage power MOS transistor S _b , control the switching and closing of the high-voltage power MOS transistor S _b , and reduce the input voltage to the output after the fast recovery diode D _b , the inductance L _b and the third filter capacitor C _b to provide certain Adjustable voltage output can be realized by changing the duty ratio of the pulse signal to the required voltage value under the power; on the basis of the mains input module 11, the DC_DC step-down module 12 is connected, and the comparison is complicated. For the switching power supply module with transformer and the direct use of DC regulated power supply to supply power to the wireless energy transmission system, fewer devices are used, the design is simpler, and it is easy to system integration and productization. Therefore, for the wireless energy designed from the mains input However, the conversion efficiency is related to the difference between the output and input voltage, and the greater the difference between the output voltage and the input voltage, the lower the conversion efficiency. Generally speaking, only when the output voltage is more than 20% of the input voltage can the module have a high efficiency, otherwise the efficiency will be relatively low, and it is no longer suitable for a high-efficiency wireless energy transmission system.

The primary inverter module ₂ includes a _first switch MOS transistor S1 and a _second switch MOS transistor S2, the drain terminal _of S2 is connected to the source terminal of S1, and the source terminal is grounded; the primary inverter module 2 passes through The gates of the first switch MOS transistor S ₁ and the second switch MOS transistor S ₂ are respectively given two high-frequency pulse signals with 180-degree anti-phase duty ratio of 50% (the frequency of the pulse signal needs to be the same as that of the WPT module) The resonant frequency remains the same), at this time, the two tubes are turned on alternately, and the input DC voltage is converted into a high-frequency square wave voltage output.

The primary impedance matching module 5 includes a first matching inductor L _f , a first matching capacitor C _f , a second matching inductor L _m2 and a second matching capacitor C _m2 ; one end of the first matching inductor L _f is connected to the The source end of the _first switch MOS transistor S1 is connected, and the other end is connected to one end of the first matching capacitor C _f ; one end of the second matching capacitor C _m2 is connected to the other end of the first matching capacitor C _f and the other end of the first matching capacitor C f One end of the second matching inductance L _m2 is connected, the other end of the C _m2 is grounded, and the other end of the second matching inductance L _m2 is connected to one end of the primary resonance compensation capacitor C _p ; as mentioned above, the The application of the DC_DC step-down module 12 is related to its output and input voltage difference, and its conversion efficiency determines its applicability. After passing through the mains input module, the input voltage of the DC_DC step-down module is 308V±10% high-voltage direct current. In order to To make it suitable for wireless energy transmission systems, it is necessary to ensure that the input and output voltage difference is within a reasonable range, that is, its output voltage cannot be too small; however, when the SS topology magnetic resonance wireless energy transmission system corresponds to a large load, due to Due to its own characteristics, the primary reflection impedance corresponding to the WPT module is very small, that is, the equivalent port impedance of its input terminal is very small, which means that it only needs a small supply voltage to meet a certain power output. The function of the primary impedance matching module 6 is to increase the output impedance of the original primary inverter module 2 from the original smaller input impedance of the WPT module 3 to a larger impedance value, thereby improving the performance in meeting the requirements. The voltage required by the primary inverter module 2 under the condition of a certain power output, that is, the output voltage of the DC_DC step-down module 5 is increased to meet the application in the SS topology magnetic resonance wireless energy transmission system at this time. Referring to FIG. 2 , the specific design principles and processes of the primary impedance matching module 6 are as follows:

As shown in FIG. 2 , the input port impedance of the primary impedance matching module 6 viewed from the left side of the capacitor C _m2 can be expressed as

Z _e2 =R _e2 +jX _e2 (1)

Let the equivalent port impedance of the input end of the WPT module 3 be R _ep , in order to apply this impedance transformation network to the transformation of R _ep , the imaginary part of the equivalent impedance of the above formula must be 0, and the real part is equal to The larger target matching equivalent impedance _Re2 we need, that is, for the above formula, it needs to satisfy

Wherein, X _m3 and X _m4 are the reactance values of the second matching capacitor C _m2 and the second matching inductance L _m2 , respectively.

For the above equations, there is a real solution only when R _e2 > R _ep , and the parameters of the matching network are:

which is

Wherein, f is the resonant frequency of the WPT module.

But at this time, the complete primary impedance matching module 6 also needs to include the first matching inductor L _f and the first matching capacitor C _f in the primary impedance matching module 6 , because the output of the primary inverter module 2 is high In order to reduce the frequency square wave voltage, it is necessary to design a resonant filter network composed of a first matching inductor L _f and a first matching capacitor C _f to filter the output high frequency square wave voltage into a nearly standard sinusoidal alternating current. Otherwise, the impedance matching The results will be very inaccurate. At this time, the design of LC parameters can be based on

Design, R is the equivalent port impedance of the output end of the primary impedance matching module 5, and R=R _e2 , where R _e2 is matched to a larger impedance value, so that the primary inverter module 2 The power supply voltage required for the power supply of the first stage increases, which can be achieved efficiently by adding the relatively simple DC_DC step-down module 12 on the basis of the mains input module 11, thereby reducing the complexity of the front-stage power supply module, and when The higher the voltage required by the primary inverter module 2 is, that is, the higher the voltage value of the step-down output of the DC_DC step-down module 12 is, the higher the step-down conversion efficiency thereof is.

The WPT module 3 includes a primary transmitting coil L _p and its primary resonance compensation capacitor C _p connected in series with each other, a secondary receiving coil L _s and its secondary resonance compensation capacitor C _s connected in series with each other, and a primary transmitting coil connected in series with each other. L _p and its primary resonance compensation capacitor C _p are arranged relative to each other in series with the secondary receiving coil L _s and its secondary resonance compensation capacitor C _s ; during specific operation, the primary transmitting coil L _p and its primary resonance compensation capacitor C _p constitute The primary resonance circuit, the secondary receiving coil L _s and its secondary resonance compensation capacitor C _s constitute the secondary resonance circuit, the frequency of the output AC voltage of the primary inverter module is the same as the natural frequency of the two resonance circuits in the magnetic coupling resonance part, and the primary inverter The energy injected by the module is converted from electric energy to magnetic field energy in the primary-side resonant circuit. When the electromagnetic field generated by the primary transmitting coil _Lp is induced by the secondary-side resonant circuit with the same resonant frequency, the two resonant circuits will resonate. And the energy is transmitted between the inductive coils in the form of an electromagnetic field, and finally the magnetic field energy-electrical energy conversion of the resonant circuit at the receiving end is used to supply power to the subsequent module. In the WPT module, the commonly used coil structures are planar helical coils and three-dimensional helical coils. Once the coil is determined and the resonant frequency is determined, its transmission characteristics are determined. In order to obtain better transmission characteristics, such as efficiency, it is necessary to improve the traditional coil form. Referring to FIG. 3 , the primary transmitting coil L _s includes a primary U-shaped magnetic core and a wire spirally wound at the bottom of the primary U-shaped magnetic core, and the secondary receiving coil L _p includes a secondary U-shaped magnetic core and is spirally wound on the secondary U-shaped magnetic core. The wire at the bottom of the primary U-shaped magnetic core, and the openings of the primary U-shaped magnetic core and the secondary U-shaped magnetic core are opposite, and the coil wire wire is a single-strand copper wire or a multi-strand Litz wire. Specifically, in the present invention, the primary and secondary coils are consistent with the magnetic core, the coil diameter (diameter) r is 1 mm, the number of turns is 28, the cross section of the magnetic core is square, the side length D ₁ =18 mm, and the length D ₂ = 44mm, _D3 =20mm, spacing d=30mm. The efficiency of the WPT module is related to parameters such as the mutual inductance between the primary and secondary coils. Under the condition that other parameters are determined, the greater the mutual inductance, the higher the transmission efficiency. Compared with the traditional coil form, the primary U-shaped magnetic coil with a spiral wound wire The openings of the core and the secondary U-shaped magnetic core are opposite, which optimizes the magnetic coupling path between the coils, increases the mutual inductance between the coils, and further enhances the magnetic field coupling effect, thereby improving the transmission efficiency of the WPT module.

The secondary impedance matching module 6 includes a third matching inductor L _m1 and a third matching capacitor C _{m1 connected} to one end of L _m1 ; The input end of the rectifier bridge is connected, and the other end of the third matching inductor L _m1 is connected to one end of the secondary resonance compensation capacitor; the function of the secondary impedance matching module 6 is to connect the output port impedance of the WPT module 3 Matching it to its optimal load point, because its efficiency corresponding to different loads is different, it is difficult for the actual application power supply load to be located at its optimal load point. Matching it to the optimal load point can effectively achieve the designed design. The maximum efficiency transmission of the WPT module 3 is described. Referring to FIG. 4 , the WPT module using SS topology in the present invention can be equivalent to the principle circuit diagram shown in FIG. 4 , where R _pr represents the internal resistance of the primary transmitting coil, R _sr represents the internal resistance of the secondary receiving coil, and R _e is The equivalent impedance cascaded at the output end of the rear stage, that is, the equivalent impedance of the input end of the secondary rectifier bridge filter module 4, ω is the resonant angular frequency of the WPT module, and M is the mutual inductance between the two coils.

Z _p and Z _s represent the impedance at both ends respectively, then the following equation can be obtained from KVL:

Two types can be launched simultaneously

By Thevenin's theorem, the equivalent load of the power supply is

Among them, the second term is the equivalent reflection impedance converted from the secondary to the transmitting end

_Zp and _Zs can be expressed as

取

那么在谐振条件下，上式可化简，得到According to series resonance condition

Pick

Then, under the resonance condition, the above formula can be simplified to get

The power equivalent load can be simplified to

This _{Zep is the equivalent port impedance R ep of} the input end of the WPT module 3 . From this formula, it can be known that R _ep and R _e are inversely proportional to each other. The greater the port impedance of the output end of the WPT module 3 The larger the electrical load is, the smaller the equivalent port impedance of the input end is, and the smaller the power supply voltage it needs under a certain power output.

The efficiency η of the magnetic resonance mechanism is defined as the ratio of the active power P _e absorbed by _Re to the active power P _p provided by the primary side input, then we can get

Under the same resonance condition, it can be simplified as:

而线圈之间的耦合系数k与互感M的关系为

将它们全部代入上式可获得WPT的传输效率η关于Q_p和Q_s、耦合系数k、等效负载R_e的效率表达式，根据

可得WPT模块的最大传输效率和对应的最佳负载点(即最佳目标匹配等效阻抗)分别为：The respective quality factors of the transmitting coil and the receiving coil are

The relationship between the coupling coefficient k between the coils and the mutual inductance M is:

Substitute them all into the above formula to obtain the efficiency expression of WPT transmission efficiency η with respect to Q _p and Q _s , coupling coefficient k, and equivalent load _Re , according to

The maximum transmission efficiency of the available WPT module and the corresponding optimal load point (that is, the optimal target matching equivalent impedance) are:

Therefore, the present invention designs the secondary impedance matching module 6 to match the impedance of the output port of the WPT module to its optimum load point, so as to realize the maximum efficient transmission of the WPT module. Referring to FIG. 5 , the input port impedance of the secondary impedance matching module 7 viewed from the left side of the third matching inductor L _m1 can be expressed as

Z _e1 =R _e1 +jX _e1 (15)

In order to apply this impedance transformation network to the transformation of _Re , the imaginary part of the equivalent impedance of the above formula must be 0, and the real part is equal to the target matching impedance we need R _opt , that is, for the above formula, to be satisfied

For the above equations, there is a real solution only when R _opt < _Re , and the parameters of the matching network are:

Wherein, X _m1 and X _m2 are the reactance values of the third matching capacitor C _m1 and the third matching inductance L _m1 , respectively.

which is

Wherein, f is the resonant frequency of the WPT module.

The secondary rectification filter module 4 includes a rectifier bridge composed of four Schottky or fast recovery diodes, and a first filter capacitor _CL connected to the output end of the rectifier bridge. The first filter capacitor _CL The other end of the rectifier is grounded; the input of the secondary rectification filter module 4 is high-frequency alternating current, and the general diode used for rectification is easily damaged and has a large loss, so it is necessary to use a Schottky with less loss and faster recovery time here. or a fast recovery type diode; the secondary rectification filter module 4 converts the high-frequency alternating current received by the secondary into a smooth and stable direct current to supply the electrical load R _L , generally, the equivalent port impedance _Re of the input terminal meets the relational

Below in conjunction with the simulation experiment, the technical effect of the present invention is further described:

1. Simulation conditions and content:

1.1 Now build the system circuit shown in Figure 1 in the PSPICE commercial software, let the output power be 30W, the load R _L is 50 ohms, C _L is 100uF, the output port impedance of the primary inverter module is the target matching of the primary impedance matching module, etc. The effective impedance _Re2 is 100 ohms, the primary coil _Lp of the designed WPT system is 121.52uH, the series resonance compensation capacitor _Cp is 83.4nF, the resonant frequency is 50k, the internal resistance _Rpr is 0.06 ohms, and the secondary coil _Lp = L _s , compensation capacitance C _p =C _s , internal resistance R _sr =R _pr , coupling coefficient k=0.105, C _b is 188.8uF, L _b is 1.73mH, C is 1000uF, and the above equations (4) (5) )(11)(16)(19) The other parameters can be calculated as C _m1 =237.34nF, L _m1 =38.48uF, C _m2 =155.08nF, L _m2 =62.69uF, L _f =590uF, C _f =17.15nF .

1.2 Simulation The average power of the input and output ports of the secondary impedance matching module and the WPT module without time addition is added. The simulation results are shown in Figure 6.

1.3 Simulation Add the power supply voltage value required by the primary impedance matching module and the primary inverter module without adding time. The simulation results are shown in Figure 7.

2. Simulation results:

As shown in Figure 6, Figure 6(a) is the average power curve between the input port and the output port of the WPT module when the secondary impedance matching module is added, then its efficiency is output/input=31.028/32.100=0.9666; Figure 6(b) ) is the average power curve of the input port and output port of the WPT module without the secondary impedance matching module, and the efficiency can be obtained as 0.8646 in the same way. It can be seen that the introduction of the secondary impedance matching module has greatly improved the WPT module. transmission efficiency.

As shown in Figure 7, Figure 7(a) is the voltage value required by the input terminal of the primary inverter module when the primary impedance matching module is added, which is 122V. At this time, the voltage is relatively high, and the difference compared with the voltage of 308V±10% is not Especially large, it can maintain the input and output voltage difference of the DC_DC module within a reasonable range, so that the input power module composed of the mains input module and the DC_DC step-down module can be applied, and the system can be simplified; When the impedance matching module is used, the voltage value required by the input terminal of the primary inverter module (the output power of the final load is 30W unchanged) is only 27.3V at this time. At this time, the DC_DC step-down module will no longer be suitable for the power supply of the front end of the primary inverter module. .

Claims (4)

1. A magnetic resonance wireless energy transmission system based on SS topology comprises an input power supply module (1), a primary inversion module (2), a WPT module (3) and a secondary rectification and filtering module (4) which are connected in sequence, wherein:

the input power supply module (1) is used for converting input alternating current commercial power into adjustable direct current for output;

the primary inversion module (2) is used for converting input direct-current voltage into high-frequency alternating-current voltage and outputting the high-frequency alternating-current voltage, and comprises a first switching MOS (metal oxide semiconductor) transistor S ₁ And a second switching MOS transistor S ₂ ，S ₂ Drain terminal of and S ₁ The source terminal is connected with the ground;

the WPT module (3) is used for realizing wireless energy transmission of electric energy-magnetic energy-electric energy and comprises primary transmitting coils L which are mutually connected in series _p And primary resonance thereofCompensation capacitor C _p And secondary receiving coils L connected in series with each other _s And its secondary resonance compensation capacitor C _s And primary transmitting coils L connected in series _p And its primary resonance compensation capacitor C _p With secondary receiving coils L connected in series _s And its secondary resonance compensation capacitor C _s Relatively arranging;

the secondary rectifying and filtering module (4) is used for converting input high-frequency alternating current into smooth and stable direct current for output, and comprises a rectifying bridge formed by four Schottky or fast recovery type diodes and a first filtering capacitor C connected with one end of the output end of the rectifying bridge _L Said first filter capacitor C _L The other end of the output of the rectifier bridge is grounded;

the method is characterized in that:

the input power supply module (1) comprises a mains supply input module (11) and a DC _ DC voltage reduction module (12), wherein the mains supply input module (11) is used for converting input alternating-current mains supply into smooth and stable direct current for output and comprises a power frequency rectifier bridge and a second filter capacitor C, one end of the power frequency rectifier bridge is connected with one end of the second filter capacitor C, and the other end of the power frequency rectifier bridge is grounded; the DC _ DC voltage reduction module (12) is used for realizing adjustable voltage reduction output of the direct current output by the input power module (1) and comprises a high-voltage power MOS (metal oxide semiconductor) transistor S _b Fast recovery diode D _b Inductor L _b And a third filter capacitor C _b (ii) a The high-voltage power MOS tube S _b The drain terminal of the second filter capacitor is connected with the end of the second filter capacitor C which is not grounded; the fast recovery diode D _b Negative electrode and S _b The source terminal of the anode is connected with the anode; the inductance L _b One end of the diode and the fast recovery diode D _b The negative electrode is connected with the other end of the third filter capacitor C _b And the first switch MOS tube S ₁ Is connected to the drain terminal of the third filter capacitor C _b The other end of the first and second electrodes is grounded;

a primary impedance matching module (5) is connected between the primary inverter module (2) and the WPT module (3), the primary impedance matching module (5) is used for improving the impedance of an output end port of the primary inverter module (2), and comprises a first matching inductor L _f A first matching capacitor C _f The first stepTwo matching inductors L _m2 And a second matching capacitor C _m2 (ii) a The first matching inductor L _f And the first switch MOS tube S ₁ Source terminal and second switching MOS transistor S ₂ Is connected with the drain terminal of the first matching capacitor C, and the other end of the first matching capacitor C is connected with the drain terminal of the second matching capacitor C _f One end of the two ends are connected; the second matching capacitor C _m2 And the first matching capacitor C _f And the other end of said second matching inductance L _m2 Is connected to one end of C _m2 Is grounded, and the second matching inductor L _m2 And the other end of the primary resonance compensation capacitor C _p One end of the two ends are connected;

a secondary impedance matching module (6) is connected between the WPT module (3) and the secondary rectifying and filtering module (4), the secondary impedance matching module (6) is used for matching the output port impedance of the WPT module (3) to the optimal load point, and comprises a third matching inductor L _m1 And with L _m1 Third matching capacitor C with one end connected _m1 (ii) a The third matching capacitor C _m1 Two ends of the third matching inductor are connected with the input end of the rectifier bridge in the secondary rectifying and filtering module (4), and the third matching inductor L _m1 And the other end of the secondary resonance compensation capacitor C _s One end of the two ends are connected;

the WPT module (3) has a primary transmitting coil L _s Comprises a primary U-shaped magnetic core, a lead spirally wound at the bottom of the primary U-shaped magnetic core, and a secondary receiving coil L _p The transformer comprises a secondary U-shaped magnetic core and a conducting wire spirally wound at the bottom of the secondary U-shaped magnetic core, and the openings of the primary U-shaped magnetic core and the secondary U-shaped magnetic core are opposite.

2. The SS topology based magnetic resonance wireless energy transfer system according to claim 1, wherein: the first matching inductor L _f And a first matching capacitor C _f And a second matching inductance L _m2 And a second matching capacitor C _m2 The following conditions are respectively satisfied:

wherein, ω is 2 pi f, f is the resonance frequency of the WPT module, R is the equivalent port impedance of the output end of the primary impedance matching module, R is the equivalent port impedance of the WPT module, R is the WPT _e2 Matching the equivalent impedance for the target, and R ═ R _e2 ，R _ep The equivalent port impedance of the input end of the WPT module to be matched.

3. The SS topology based magnetic resonance wireless energy transfer system according to claim 1, wherein: the third matching inductor L _m1 And a third matching capacitor C _m1 The following conditions are satisfied:

wherein f is the resonance frequency of the WPT module, R _opt Matching the equivalent impedance, R, for an optimum target _e The impedance of the equivalent port of the input end of the secondary rectifying and filtering module to be matched.

4. The SS topology based magnetic resonance wireless energy transfer system according to claim 1, wherein: the wire spirally wound at the bottom of the primary U-shaped magnetic core and the wire spirally wound at the bottom of the secondary U-shaped magnetic core adopt a single-stranded copper wire or a plurality of strands of litz wires.

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