CN204992792U - Add bi -polar impedance transforming network's resonant mode wireless power transmission system - Google Patents

Abstract

The utility model provides a resonant wireless power transmission system added with a double-terminal impedance transformation network. The system includes a high-frequency power source module, a primary-side impedance transformation network, a secondary-side impedance transformation network, a transmission coil module, and a load. Among them, the high-frequency power source module is composed of ideal power supply and internal resistance, which provides electric energy for the whole system. The transmission coil module is composed of a transmitting coil and a receiving coil to realize wireless transmission of electric energy. The primary-side impedance matching network is connected to the high-frequency power source module and the transmitting coil respectively, which can realize the maximum power output of the high-frequency power source; the secondary-side impedance transformation network is connected to the receiving coil and the load respectively, which can realize the external transmission efficiency of the high-frequency power source Highest. The utility model can realize the maximum output power of the high-frequency power source by adding appropriate impedance transformation networks on the primary side and the secondary side of the resonant wireless power transmission system, and at the same time the system can obtain the highest transmission efficiency, thereby ensuring the maximum power obtained by the load.

Description

A resonant wireless power transfer system with added double-terminal impedance transformation network

technical field

The utility model relates to a resonant wireless power transmission system, in particular to a resonant wireless power transmission system added with a double-terminal impedance transformation network.

Background technique

In the process of signal or electric energy transmission, in order to realize signal transmission without reflection or maximum power transmission, it is required that the circuit can realize impedance matching. Impedance matching is related to the performance of the system, and the impedance matching of the circuit can optimize the performance of the system.

Usually, there are two purposes to achieve impedance matching: one is to eliminate the reflected wave between the signal source (or power supply) and the load to ensure the transmission quality of the transmitted signal. This impedance matching is called no reflection matching; the other is to make the power supply (or power supply) Signal source) output maximum power, this impedance matching is called maximum output power matching. This patent mainly designs an appropriate impedance transformation network for the second case, so as to realize the maximum power output of the high-frequency power source module.

Secondly, the resonant wireless power transmission technology has the characteristics of long transmission distance, relatively high transmission efficiency, and non-radiation, and is especially suitable for medium-distance wireless power transmission. Its main components are the transmission coil and the load. The transmission coil generally achieves a resonance state by self-resonance or an external capacitor, so as to realize the effective transmission of electric energy. However, in practical applications, the transmission coil is not an ideal coil. Its internal resistance must be considered, and the load resistance is not as large as possible. It has an optimal value to maximize the transmission efficiency of the system. When the load resistance is not the optimal value, it can be equivalent to the optimal value by adding an appropriate impedance transformation network, so that the transmission efficiency of the system is the highest.

Utility model content

The purpose of the utility model is to overcome the problem of low power output power and low system transmission efficiency in the current resonant wireless power transmission system, and provide a resonant wireless power transmission system added with a double-terminal impedance transformation network.

The purpose of the utility model is at least achieved by one of the following technical solutions.

A resonant wireless power transmission system adding a double-terminal impedance transformation network, including a high-frequency power source module, a transmission coil module, a primary-side impedance transformation network, a secondary-side impedance transformation network, and a load; wherein the high-frequency power source module is composed of an ideal voltage The source and the internal resistance are connected in series to provide power for the system; the transmission coil module includes a transmission coil and a reception coil, where the transmission coil is equivalent to an RLC series resonance mode formed by the internal resistance of the transmission coil, the inductance of the transmission coil and the resonant capacitance of the transmission coil. The coil is equivalent to the RLC series resonance mode formed by the internal resistance of the receiving coil, the inductance of the receiving coil and the resonant capacitance of the receiving coil; the input end of the primary impedance transformation network is connected to the output end of the high-frequency power source module, and the output end is connected to the transmission coil module The transmitting coil TX in the circuit is connected; the input terminal of the secondary impedance transformation network is connected with the receiving coil in the transmission coil module, and the output terminal is connected with the load.

Further, according to Thevenin's theorem and Norton's theorem, the high-frequency power source module can be equivalent to an ideal voltage source U _S and the equivalent power supply internal resistance _RS in series, and can also be equivalent to an ideal current source _IS and the equivalent The parallel connection form of the internal resistance R _S of the power supply satisfies the relationship of U _S = R _S · I _S. When the equivalent resistance outside the high-frequency power source module is _Req and _Req = R _S , the high-frequency power source The maximum output power P _max of the module satisfies The frequency f of the high-frequency power source module is 0.5-50 MHz, and the waveform of the voltage source or the current source is a sine wave.

Further, the internal resistance R _L1 of the transmitting coil and the internal resistance R _L2 of the receiving coil both include ohmic internal resistance and radiation internal resistance; the transmitting coil and the receiving coil satisfy the relationship: ω is the angular frequency of the system, satisfying ω=2πf _, L ₁ is the inductance of the transmitting coil, C ₁ is the resonant capacitance of the transmitting coil, L ₂ is the inductance of the receiving coil, and C ₂ is the resonant capacitance of the receiving coil, that is, the transmitting coil and the receiving coil are at the system frequency Series resonance occurs under, and the mutual inductance between the transmitting coil and the receiving coil is M.

Further, the distance between the transmitting coil and the receiving coil in the transmitting coil module is within half a wavelength of the electromagnetic wave; the distance between the transmitting coil and the receiving coil is not less than the frequency bifurcation range.

Further, the load is purely resistive, resistive-inductive or resistive-capacitive.

Further, both the primary-side impedance transformation network and the secondary-side impedance transformation network are composed of energy storage elements, which do not consume electric energy. The energy storage elements include capacitors and inductors. The circuit form of the primary-side impedance transformation network and the secondary-side impedance transformation network is L Type, T type or Π type.

Further, there is an optimal load R _L.Optimal when the external transmission efficiency η of the high-frequency power source module reaches the maximum value, satisfying $R_{L.optimal}=\sqrt{R_{L2}^2+\frac{R_{L2}}{R_{L1}}{\left(\mathrm{\ω}m\right)}^2}.$

Further, if the load _RL is not equal to the optimal load _RL.Optimal , then add a secondary impedance transformation network between the receiving coil and the load _RL , so that the equivalent resistance seen from the output end of the receiving coil to the load is R _L.Optimal ; Since the secondary impedance transformation network does not consume electric energy, the electric energy consumed by the equivalent resistance R _L.Optimal is equal to the electric energy consumed by the load R _L , that is, the system can realize the highest efficiency transmission at this time.

Further, the equivalent resistance R _eq outside the high-frequency power source module satisfies: If R _eq ≠ R _S , add a primary-side impedance transformation network between the output end of the high-frequency power source module and the input end of the transmitting coil, so that the equivalent resistance R seen from the output end of the high-frequency power source module to the transmitting coil ′ _eq satisfies: R′ _eq = R _S , then the output power of the high-frequency power source module is maximum at this time; since the primary-side impedance transformation network is composed of energy storage element capacitance and inductance, and does not consume electric energy, the high-frequency power source module The output electric energy is equal to the electric energy consumed by the input terminal of the transmitting coil. According to the formula P _22' = P _11' η, P _22' is the power consumed by the load, and P _11' is the output power of the high-frequency power source module. At this time, the load Resistor _RL gets the most power.

Compared with the prior art, the utility model has the following advantages and technical effects:

The utility model can ensure the maximum output power of the high-frequency power source module by adding appropriate impedance transformation networks on both sides of the transmitting coil and the receiving coil, and at the same time ensure the highest transmission efficiency outside the high-frequency power source module, so that the load resistance can be maximized power.

Description of drawings

Fig. 1 is a system block diagram of the utility model.

Fig. 2 is an internal equivalent circuit diagram of the high-frequency power source module.

Figure 3a and Figure 3b are two internal structure diagrams of the impedance transformation network (taking the L type as an example).

detailed description

The specific implementation of the utility model will be further described below in conjunction with the accompanying drawings, but the implementation and protection of the utility model are not limited thereto.

As shown in Figure 1, a resonant wireless power transmission system with a double-terminal impedance transformation network includes a high-frequency power source module I, a transmission coil module II, a primary-side impedance transformation network N1, a secondary-side impedance transformation network N2, and a load R _L ; wherein the high-frequency power source module I is composed of an ideal voltage source U _S and an internal resistance R _S in series to provide electric energy for the system; the transmission coil module II includes a transmitting coil TX and a receiving coil RX, wherein the transmitting coil TX is equivalent to a transmission coil TX The RLC series resonance mode formed by the coil internal resistance R _L1 , the transmitting coil inductance L1 and the transmitting coil resonant capacitance C1, the receiving coil RX is equivalent to the RLC formed by the receiving coil internal resistance R _L2 , the receiving coil inductance L2 and the receiving coil resonant capacitance C2 In series resonance mode, the mutual inductance between the transmitting coil TX and the receiving coil RX is M; the input terminal of the primary impedance transformation network N1 is connected to the output terminal of the high-frequency power source module, and the output terminal is connected to the transmitting coil TX in module II ; The input terminal of the secondary impedance transformation network N2 is connected to the receiving coil RX in the module II, and the output terminal is connected to the load _RL .

The output port of the high-frequency power source module is 11'; the port of the transmitting coil TX is 33', the port of the receiving coil RX is 44', and the access port of the load _RL is 22'. The input terminal of the primary impedance transformation network N1 is connected to the port 11', the output terminal is connected to the transmitting coil TX port 33'; the input terminal of the secondary impedance transformation network N2 is connected to the receiving coil RX port 44', and the output terminal is connected to the load port 22'.

The high-frequency power source module I provides electric energy for the entire resonant wireless power transmission system, and its output waveform is a high-frequency sine wave. By designing appropriate parameters for the secondary impedance transformation network N2, the equivalent resistance value seen from port 44' to the right can be the optimal value R _L.Optimal , and R _L.Optimal satisfies the expression Therefore, the transmission efficiency outside the high-frequency power source module is the highest. The primary side impedance transformation network N1 can make the equivalent resistance seen from the port 11' to the right equal to the matching resistance R _S of the high-frequency power source module by designing appropriate parameters, so that the high-frequency power source module can output the maximum power. By adding the primary-side impedance transformation network N1 and the secondary-side impedance transformation network N2, the load resistor _RL finally obtains the maximum power.

As shown in Figure 2, according to Thevenin's theorem or Norton's theorem: any active two-port network or actual power supply can be equivalent to a series form of an ideal voltage source U _S and the internal resistance _RS of the power supply, or equivalent to an ideal current The parallel connection form of the source I _S and the power source resistance _RS , both of which satisfy the relation U _S =R _S ·I _S . When the equivalent resistance outside the high-frequency power source module is _Req , and when _Req = R _S is satisfied, the high-frequency power source module outputs the maximum power P _max , which satisfies The frequency of the high-frequency power source module is f, the value range is 0.5-50MHz, and its waveform is a high-frequency sine wave.

The structure of the transmission coil mainly has two types: planar disk type and space spiral type. The advantage of the planar disk coil is that it occupies a small space, is convenient for actual installation, and has a wide range of practical applications; the space spiral coil can generate a relatively uniform magnetic field. Any coil can be equivalent to the series form of its internal resistance and its inductance, and its internal resistance includes ohmic resistance and radiation resistance. If you want to realize the resonant wireless power transmission of the coil, you generally need to connect an external resonant capacitor in series to make it meet the RLC series resonant frequency equal to the system angular frequency ω, and satisfy ω=2πf; if the self-resonant state is achieved under the action of the coil parasitic capacitance , and the self-resonant frequency is exactly equal to the system frequency, there is no need to add an external capacitor. Of course, the present invention includes various types of coils, and is not limited thereto.

As shown in Figure 3a and Figure 3b, different impedance transformation networks can be selected for different loads. The impedance transformation networks mainly include L-type, T-type, ∏-type and other types. The utility model will temporarily use the L-type impedance transformation network as an example to illustrate , but not limited to this. For the purely resistive load _RL , it can be equivalent to any target resistance value by adding an L-type impedance transformation network. The L-shaped impedance transformation network mainly has two connection methods, as shown in Figure 3a and Figure 3b, where the energy storage elements X1 and X2 are a combination of inductors or capacitors (cannot be capacitors or inductors at the same time), and Figure 3a is a positive L-shaped impedance Transformation network, by designing appropriate capacitance and inductance parameters, the positive L-shaped impedance transformation network can equivalent the original resistance R to any target resistance _Req3 , where _Req3 >R; Figure 3b is an inverted L-shaped impedance transformation network, through the design With proper capacitance and inductance parameters, the inverted L-shaped impedance transformation network can equate the original resistance R to any target resistance _Req4 , where _Req4 <R.

The specific steps of this system design method are as follows: in the known ideal voltage source U _S of the high-frequency power source module, internal resistance R _S , power supply frequency f, transmitting coil inductance L1 and internal resistance R _L1 , receiving coil inductance L2 and internal resistance Under the conditions of R _L2 , mutual inductance M, and load resistance R _L : (1) First, adjust the resonant capacitance (C1, C2) of the transmitting coil and receiving coil to meet Where ω = 2πf, that is, the system reaches the resonance state at this time. (2) Compare the actual load resistance R _L with the optimal resistance value R _L.Optimal when the system transmits maximum efficiency ( ), if R _L <R _L.Optimal , then add a positive L-type impedance transformation network at the load end to perform impedance transformation, and adjust the parameters of its internal energy storage element, so that the equivalent resistance seen from port 44' is R _L.Optimal ; if R _L >R _L.Optimal , then add an inverted L-shaped impedance transformation network at the load end to perform impedance transformation, and adjust the parameters of its internal energy storage elements, so that the equivalent energy seen from port 44' The effective resistance is _RL.Optimal . At this time, the maximum external transmission efficiency of the high-frequency power source module can be achieved. (3) Compare the external equivalent resistance R _eq of the high-frequency power source module with the size of the internal resistance R _S of the power supply (where ): If R _eq < R _S , then add a positive L-shaped impedance transformation network between the high-frequency power source module and the transmitting coil TX to perform impedance transformation, and adjust the parameters of its internal energy storage element so that the slave port 11' The equivalent resistance looking into the transmitting coil is R _S ; if _Req > R _S , add an inverted L-shaped impedance transformation network between the high-frequency power source module and the transmitting coil TX to perform impedance transformation and adjust its internal The parameters of the energy storage element are such that the equivalent resistance seen from the port 11' to the transmitting coil is R _S . According to the maximum power transmission condition, the high-frequency power source module will output the maximum power at this time, so the load will also obtain the maximum power.

Claims (5)

1. A resonant wireless power transmission system that adds a double-terminal impedance transformation network is characterized in that it includes a high-frequency power source module (I), a transmission coil module (II), a primary impedance transformation network (N1), and a secondary impedance Transformation network (N2) and load ( _RL ); among them, the high-frequency power source module (I) is composed of an ideal voltage source (U _S ) and internal resistance (R _S ) in series to provide power for the system; the transmission coil module (II) Including the transmitting coil (TX) and the receiving coil (RX), where the transmitting coil (TX) is equivalent to the RLC series formed by the transmitting coil internal resistance (R _L1 ), the transmitting coil inductance (L1) and the transmitting coil resonant capacitance (C1) Resonance mode, the receiving coil (RX) is equivalent to the RLC series resonance mode formed by the internal resistance of the receiving coil (R _L2 ), the inductance of the receiving coil (L2) and the resonant capacitance of the receiving coil (C2); the primary impedance transformation network (N1) The input terminal of N2 is connected with the output terminal of the high-frequency power source module, and the output terminal is connected with the transmitting coil (TX) in the transmission coil module (II); the input terminal of the secondary impedance transformation network (N2) is connected with the transmission coil module (II) The receiving coil (RX) in the circuit is connected, and the output terminal is connected to the load ( _RL ). 2. A resonant wireless power transmission system adding a double-terminal impedance transformation network according to claim 1, characterized in that the internal resistance of the transmitting coil (R _L1 ) and the internal resistance of the receiving coil (R _L2 ) both include ohmic internal resistance and radiation internal resistance; the transmitting coil (TX) and receiving coil (RX) satisfy the relationship: ω is the angular frequency of the system, satisfying ω=2πf, L ₁ is the inductance of the transmitting coil, C ₁ is the resonant capacitance of the transmitting coil, L ₂ is the inductance of the receiving coil, and C ₂ is the resonant capacitance of the receiving coil, that is, the transmitting coil (TX) and the receiving coil (RX) series resonance occurs at the system frequency, and the mutual inductance between the transmitting coil (TX) and the receiving coil (RX) is M. 3. A kind of resonant wireless power transmission system adding a double-terminal impedance transformation network according to claim 2, characterized in that between the transmitting coil (TX) and the receiving coil (RX) in the transmitting coil module (II) The distance is within half a wavelength of the electromagnetic wave; the distance between the transmitting coil (TX) and the receiving coil (RX) is not less than the frequency bifurcation range. 4. The resonant wireless power transmission system adding a double-terminal impedance transformation network according to claim 1, characterized in that the load ( _RL ) is purely resistive, resistive-inductive or resistive-capacitive. 5. A kind of resonant wireless power transmission system adding a double-terminal impedance transformation network according to claim 1, characterized in that, both the primary side impedance transformation network (N1) and the secondary side impedance transformation network (N2) are composed of storage The energy storage elements include capacitors and inductors, and the circuit forms of the primary-side impedance transformation network (N1) and the secondary-side impedance transformation network (N2) are L-type, T-type or ∏-type.