CN106253360A - A kind of based on the wireless electric energy transmission device utilizing capacity coupled two-plate structure - Google Patents

Abstract

The invention relates to a wireless power transmission device based on a bipolar plate structure utilizing capacitive coupling. The present invention designs a new capacitive electric circuit model based on the analysis of the advantages and disadvantages of the typical capacitive electric circuit model, and adds a pair of polar plate capacitances and two grounds. The high-frequency oscillation system will generate a high-frequency voltage at the connection between the capacitor and the inductor in the resonant state. When the high-frequency voltage is connected to the plate capacitor, an induced current will be generated to realize the transmission of the capacitor between the plate capacitors. Compared with inductive power transmission, the present invention has the characteristics of simple structure and slow efficiency decay with distance extension; compared with traditional capacitive power transmission structure, it has the advantages of lower working frequency and higher transmission efficiency in the case of long-distance power transmission. The present invention well solves the restriction of inductive power transfer on the surrounding environment, and is more suitable for application to situations such as high metal content in the surrounding environment, such as wireless energy transmission of different potentials on high-voltage lines.

Description

A wireless power transmission device based on a bipolar plate structure utilizing capacitive coupling

technical field

The invention relates to high-frequency resonant high-voltage electric field coupling wireless power transmission technology, in particular to a wireless power transmission device based on a bipolar plate structure utilizing capacitive coupling.

Background technique

Inductive Power Transfer Technology (IPT) has been widely applied to electric vehicles and mobile terminal equipment, and its transmission efficiency is already comparable to that of traditional wired power transmission. However, the disadvantage of inductive power transmission is that it depends on the conductor medium. When the concentration of metal substances in the air is high, the magnetic field will generate a current vortex, causing energy loss and increasing the temperature, which is very dangerous. Capacitive transmission is a good solution to this problem.

Capacitive power transfer uses an electric field instead of a magnetic field to transfer electrical energy. The electric field transmits electricity in a space with metal obstacles without causing energy loss. Therefore, capacitive power transmission is more suitable for wireless power transmission in electric vehicles and other aspects. Another advantage of capacitive transfer is low cost. Capacitive power transmission only uses metal plates, which have the advantages of good conductivity, low price, and light weight; while the coils for inductive power transmission must be wound with Litz wire, which is relatively expensive, which is very unfavorable for wireless power transmission popularity. However, the typical capacitive transmission circuit has the following two disadvantages (as shown in Figure 1): as the transmission distance increases, the coupling capacitance value becomes very small, which makes the system resonant frequency increase seriously; and at very high frequencies, The high-frequency power supply required by the system is difficult to manufacture, and the high-frequency resistance increases sharply, resulting in a rapid decline in the overall efficiency of the system. Therefore, it is difficult for the wireless power transmission system based on the traditional capacitive transfer model to realize long-distance power transmission.

Contents of the invention

Aiming at the problems existing in the background technology, the present invention designs a new capacitive electric circuit model by analyzing the advantages and disadvantages of typical electric capacitive electric circuit models. Compared with the traditional magnetic resonance, the present invention has the advantages of simple structure, weak influence by the surrounding medium, and low attenuation rate; compared with the existing capacitive electric transmission, the present invention has high transmission efficiency and does not need too high The working frequency has the advantage of high practicability.

In order to solve the problems of the technologies described above, the present invention adopts the following technical solutions:

A wireless power transmission device based on a two-plate structure utilizing capacitive coupling, including a frequency-adjustable high-frequency AC power supply, a transmitting-end resonant system, a receiving-end resonant system, a plate capacitor C ₂ and two different ground terminals GND1 and GND2 ; The plate capacitor C ₂ includes two capacitor plates, which are respectively E plate and F plate, and the E plate and the F plate are facing each other;

The high-frequency AC power supply, the resonant system of the transmitting end, the E plate of the plate capacitor C ₂ and the reference ground GND1 constitute the transmitting end; the resonant system of the receiving end, the F plate of the plate capacitor C ₂ , the load and the reference ground GND2 form the receiving end;

The conduction direction of electric energy is as follows: high-frequency AC power supply, resonant system at the transmitting end, E plate of the plate capacitor _C2 , F plate of the plate capacitor _C2 , resonant system at the receiving end, and load.

The resonant system at the transmitting end includes an inductance L1 and a tuning capacitor _C1 . The high _- frequency AC power supply and the resonant system at the transmitting end form a series loop. A and B are respectively the _two ends of the capacitor _C1 and the E plate of the plate capacitor C2. It is connected to the A terminal of the capacitor _C1 , the _A terminal is located between the inductor L1 and the tuning capacitor _C1 , and the B terminal is connected to the reference ground GND1 _; the receiving end resonant system includes the inductor L3 and the tuning capacitor _C3 , and the receiving end The resonant system and the load form a series loop, C and D are the _two ends of the capacitor C3 respectively, the F plate of the plate capacitor _C2 is connected to the C terminal _of the capacitor C3, and the C terminal is located between the inductor _L3 and the tuning capacitor _C3 , and the D terminal is connected to the reference ground GND2.

A rectification circuit is arranged between the resonant system at the receiving end and the load.

Both the resonant system at the transmitting end and the resonant system at the receiving end are coil systems with low internal resistance and high Q value.

The resonant system at the transmitting end is consistent with the natural frequency of the resonant system at the receiving end.

The plate capacitor is made of aluminum foil paper or iron plate, but not limited to the above two materials.

Compared with inductive power transmission, the present invention has the characteristics of simple structure and slow efficiency attenuation with distance extension; compared with traditional capacitive power transmission structure, it has the advantages of lower working frequency and higher transmission efficiency in the case of long-distance power transmission. The present invention well solves the limitation of inductive power transfer on the surrounding environment, and is more suitable for application to situations such as high metal content in the surrounding environment, such as wireless energy transmission of different potentials on high-voltage lines.

Description of drawings

Figure 1 is a typical capacitive power transmission circuit diagram;

Fig. 2 is a schematic diagram of the present invention's improved capacitive transmission;

Fig. 3 is the realization diagram of the system of the present invention;

Fig. 4 is the capacitive electric circuit diagram of the present invention;

Fig. 5 is an equivalent circuit diagram of the present invention;

Fig. 6 is a schematic diagram of plate capacitive coupling.

detailed description

As shown in Fig. 2, the present invention includes frequency adjustable AC power supply, two sets of resonant systems, plate capacitors and two grounds. The transmitting end consists of a high-frequency AC power supply, the resonant system of the transmitting end, the E plate of the plate capacitor C ₂ and the reference ground GND1; the receiving end consists of the receiving end resonant system, the F plate of the plate capacitor C ₂ , the load and the reference ground GND2. The resonant system at the transmitting end includes inductance L ₁ and tuning capacitor C ₁ , the high-frequency AC power supply and the resonant system at the transmitting end form a series loop, the E plate of the plate capacitor C ₂ is connected to the A terminal of the capacitor C ₁ , and the B terminal of the capacitor C ₁ Connect to the reference ground GND1; the resonant system at the receiving end includes an inductor L ₃ and a tuning capacitor C ₃ , the resonant system at the receiving end forms a series loop with the load, the F plate of the plate capacitor C ₂ is connected to the C terminal of the capacitor C ₃ , and the capacitor C ₃ The B end of the terminal is connected to the reference ground GND2; the E and F plates of the plate capacitor C ₂ are facing each other. The transmitting end and the receiving end are connected wirelessly, and the energy transmission is carried out only through the plate capacitance. For example, in high-voltage lines, this kind of wireless energy transmission system between different potentials can be used to power some detection equipment.

The resonant system at the transmitting end will generate a large high-frequency and high _- voltage voltage at point _A at the junction of capacitor _C1 and inductor L1 in the resonant state. A transmission loop can be formed between the plate capacitor and the reference ground of the receiving end, and a high-frequency electric field will be generated at _both ends of E and F of the plate capacitor C2, thereby generating an induced current. Driven by the high-frequency electric field, the high-frequency voltage generated by the resonant system causes a high-frequency electric field to be generated between the plate capacitors, and a rapidly changing induced current I ₂ is generated between the plate capacitors. When the induced current I ₂ passes through the receiving end capacitor C ₃ , An induced voltage of the same frequency will be generated on C ₃ , and cause the loop resonance of the receiving end loop C _{3 -L 3} -RL, thereby generating a large current and consuming large power on the receiving end load. In this way, the transmitting end provides energy, the receiving end and the load consume energy, and wireless transmission of electric energy is realized.

_In the system involved in the present invention, the amplitude of the induced current I in the transmission loop is relatively small, at the mA level, so it is difficult to generate power in the transmission loop, so the system has low requirements on the parasitic resistance of the transmission loop, and the transmission capacitance Even if the resistance of the loop is large (such as 5kΩ), it will not significantly affect the transmission efficiency of the system. Therefore, in actual use, it is sufficient to use common metal materials such as aluminum foil paper and iron plates to construct plate capacitors. This is also an important feature of the present invention.

The two grounds GND1 and GND2 of the present invention do not necessarily have to be connected to the same ground, but can be connected to different reference grounds, but the connected reference must be stable. The so-called stability means that when the charge flows in and out of the reference ground, it must be guaranteed The stability of its reference potential. The low-voltage sides of the two resonant capacitors are respectively connected to a stable reference ground potential. The two reference grounds connected to the system can provide a stable reference point for the high-frequency changing potential on the transmission loop and the receiving loop, thereby constructing the induction current flow loop. For the resonant high voltage with high frequency changes, the two stable reference grounds can be regarded as a short circuit. In this connection mode, the plate capacitance and the reference ground form a loop, and the system generates a rapidly changing current between the plate capacitances, energy Passed across the plate capacitance.

Step 1 Selection of high frequency AC power supply

The AC power supply needs to have the following three characteristics:

1) The frequency is stable. It can work stably at the resonant frequency of the system for a long time, and the frequency fluctuation must be as small as possible.

2) The frequency is adjustable. Since the wound coils or produced capacitors cannot be guaranteed to be exactly the same, and the working environment of the system will also be different, the resonant frequencies of different wireless energy transfer systems cannot be exactly the same. The designed power supply needs to be able to adapt to different systems, that is, the frequency must be adjustable.

3) Low internal resistance. In order to reduce the energy consumed by the high-frequency AC power supply, it is necessary to choose a power supply with a small internal resistance.

Based on the above requirements, the AC power supply used in the present invention is composed of a DC power supply and an inverter circuit, and the selected inverter circuit has the function of manually adjusting the working frequency, which can not only conveniently and intuitively see the working effect under different frequencies, but also Make the selected high-frequency AC power supply adapt to different systems.

Step 2 Selection of resonant system

The inductance of the resonant system selected in the present invention is a coil system with low internal resistance and high Q value. The internal resistance of the coil is low and the Q value is high, and the system can easily obtain a large induced current, which makes the electric field energy in the middle of the plate capacitor higher, and also reduces the energy loss caused by parasitic resistance.

Step 3 Realization of capacitive power transmission

As shown in Figure 2, two pole plates of the pole plate capacitor used in the present invention are opposite, can select simple materials such as tinfoil paper, iron plate for use, pole plate capacitance E plate connects the A end of electric capacity C ₁ , corresponds to it The corresponding plate capacitor F is connected to terminal C of capacitor _C2 , and terminals B and _D of capacitors _C1 and C3 are respectively grounded to GND1 and GND2.

1. As shown in Figure 4, it is a schematic diagram of the capacitive power transmission circuit of the present invention. Fig. 5 is an equivalent circuit diagram of the present invention. Driven by high-frequency voltage, a rapidly changing high-frequency electric field is generated at both ends of the plate capacitor C2, and the _two reference grounds can provide stable reference points for the high-frequency changing potential on the transmission loop and the receiving loop, thereby constructing the flow of induced current circuit. For the resonant high voltage with high frequency changes, the two stable reference grounds GND1 and GND2 can be regarded as a short circuit, and the plate capacitor C ₂ forms a loop with the reference ground, and the system generates a rapidly changing current I ₂ between the plate capacitors, and the energy Passed across the plate capacitance.

Figure 6 is a schematic diagram of plate capacitive coupling. The solid line arrows indicate that the high frequency voltage is in the positive half cycle, and the dotted line arrows indicate that when the high frequency voltage is in the negative half cycle, the rapid transformation of the charges on the two plates of the plate capacitor produces a rapidly changing current, thereby realizing energy transmission. The formula for calculating plate capacitance is ε ₀ ＝8.85×10 ^-12 is the vacuum dielectric constant, A is the area of the plate capacitor, d is the distance between the two plate capacitors, the capacitance of the plate capacitor is very small, only pF level can realize the energy through the electric field coupling Passed across the plate capacitance.

By establishing Kirchhoff's equations in the operating frequency band:

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; \&omega;</span>}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; j\&omega;C</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; j\&omega;C</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>\\ {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; j\&omega;C</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; j\&omega;C</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; j\&omega;C</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; j\&omega;C</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; j\&omega;C</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; ,</span>\\ {\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; j\&omega;C</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; \&omega;</span>}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; j\&omega;C</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.</span>}\end{array}\right.$

Among them, R ₁ ＝R _C1 +R _L1 +R _p , R ₃ ＝R _C3 +R _L3 +R _L , R _p is the internal resistance of the power supply, R _C1,3 , R _L1,3 are the resonance system capacitance and the internal resistance of the inductor respectively .

By deriving Kirchhoff's equations, we get The transmission power P _O =|I ₃ | ² R _L is obtained. in R ₁ =R _C1 +R _L1 +R _p , R ₃ =R _C3 +R _L3 +R _L .

After the system of the present invention is connected in sequence, the AC power supply is turned on. At this time, an induced current is generated in the system. Because of the high-frequency effect, a high-frequency voltage is generated between the capacitor and the inductor, and an induced current is generated on the plate capacitor. The natural frequencies of the receiving and transmitting resonant systems used in the present invention are consistent, the energy is transferred between the plate capacitors, and drives the resonant system at the receiving end to resonate, and the rectification circuit rectifies the received high-frequency electric energy to drive the load to work. At this time, the frequency of the AC power supply is adjusted so that the system works at different frequencies, the induced current and induced electromotive force generated by the system are changed, and the electric energy received by the load is also different. In order to enable the system to obtain higher working performance, it is only necessary to adjust the working frequency to maximize the receiving current.

Claims (5)

1. A wireless power transmission device based on a two-plate structure utilizing capacitive coupling, characterized in that: it comprises a frequency-adjustable high-frequency AC power supply, a transmitting end resonant system, a receiving end resonant system, a pole plate capacitance C ₂ and two different The ground terminal GND1, GND2; plate capacitor C ₂ includes two capacitor plates, respectively E plate and F plate, E plate, F plate is facing; The high-frequency AC power supply, the resonant system of the transmitting end, the E plate of the plate capacitor C ₂ and the reference ground GND1 constitute the transmitting end; the resonant system of the receiving end, the F plate of the plate capacitor C ₂ , the load and the reference ground GND2 form the receiving end; The conduction direction of electric energy is as follows: high-frequency AC power supply, resonant system at the transmitting end, E plate of the plate capacitor _C2 , F plate of the plate capacitor _C2 , resonant system at the receiving end, and load. 2. A wireless power transmission device based on a two-plate structure utilizing capacitive coupling according to claim 1, wherein the resonant system at the transmitting end includes an inductance L ₁ and a tuning capacitor C ₁ , a high-frequency AC power supply It forms a series loop with the resonant system of the transmitting end, A and B are the _two ends of the capacitor _C1 respectively, the E plate of the plate capacitor C2 is connected to the A terminal of the capacitor _C1 , and the _A terminal is located between the inductor L1 and the tuning capacitor _C1 Between, terminal B is connected to the reference ground GND1; the resonant system at the receiving end includes an inductor L ₃ and a tuning capacitor C ₃ , the resonant system at the receiving end forms a series loop with the load, and C and D are the two ends of the capacitor C ₃ respectively, extremely _The F plate _of the board capacitor C2 is connected to the C terminal _of the capacitor C3, the C terminal is located between the inductor L3 and the tuning capacitor C3, and the _D terminal is connected to the reference ground GND2. 3. A wireless power transmission device based on a two-plate structure utilizing capacitive coupling according to claim 2, wherein a rectification circuit is arranged between the resonant system at the receiving end and the load. 4. A wireless power transmission device based on a two-plate structure utilizing capacitive coupling according to claim 2, wherein both the resonant system at the transmitting end and the resonant system at the receiving end use low internal resistance and high Q value coil system. 5 . A wireless power transmission device based on a two-plate structure utilizing capacitive coupling according to claim 2 , wherein the natural frequency of the resonant system at the transmitting end is the same as that at the resonant system at the receiving end. 5 .