Cross-medium multi-frequency wireless power transmission system and design method

Abstract

The invention relates to a cross-medium multi-frequency wireless power transmission system and a design method. Aiming at the existing defects of wireless electric energy transmission in some complex application scenes, the invention provides an electric energy transmission system with a multi-frequency characteristic, and the system realizes multi-frequency of a repeating coil and conversion and re-transmission of transmitted energy by adding the repeating coil and an AC-AC electric energy converter; by adding and designing a series-parallel impedance structure, frequency decoupling among all parts of a multi-frequency system is realized, crosstalk among system frequencies is prevented, magnetic induction type wireless electric energy transmission can cope with a more complex (multi-medium) transmission environment, the flexibility of the system is improved, and the reliability of the system is improved. Farther transmission distance, higher transmission efficiency and higher transmission power can be considered to a higher degree.

Description

Technical Field

[0001] The present invention relates to a cross-media multi-frequency wireless power transmission system and a design method, belonging to the technical field of wireless power transmission in power electronics, and is widely applied to fields such as aerospace, ocean engineering, transportation, new energy systems, medical treatment, and military. Background Art

[0002] As a non-contact power transmission technology, wireless power transmission technology (WPT) realizes convenient, safe, and efficient access to power sources by converting electrical energy into relay energy and then converting the relay energy back into electrical energy, solving problems such as plug-and-unplug electrical energy transmission with sparking and difficult maintenance.

[0003] With the increasingly wide application of wireless power transmission technology, the application scenarios of wireless power transmission systems have gradually become diversified. As a solution for wireless power transmission, the magnetic field-based wireless power transmission technology based on a single frequency has problems of inadaptability or inability to balance the overall performance of the system. This is particularly obvious in the case of multi-transmission medium application scenarios: the media between coupled magnetic fields have different characteristics, and the magnitude of conductivity has a great impact on the transmission performance of the system, which is not conducive to realizing high-frequency power transmission; while the low-frequency power transmission system is limited in power density and its transmission efficiency will also be greatly affected. Summary of the Invention

[0004] Aiming at the problem of optimizing the cross-media wireless power transmission system, the present invention provides a new design idea. According to the characteristics of the media, different frequencies are matched in different media to transmit electrical energy to improve the overall performance of the system. The circuit topology is as shown in the appendix. Figure 1 as shown.

[0005] The system of the present invention realizes the conversion from a single-frequency system to a multi-frequency system and the re-transmission of energy by adding a relay-end coil, an AC-AC power converter, and an energy return topology, and realizes the decoupling of different frequencies by adding energy storage elements and impedance design;

[0006] The added relay-end coil is characterized in that it is composed of a single electrical energy transmitting coil, a single electrical energy relay coil, and a single electrical energy receiving coil, and includes power compensation circuits for the electrical energy transmitting coil, the relay coil, and the receiving coil;

[0007] The AC-AC power converter is characterized in that it is composed of a rectifier converter and an inverter converter in cascade, realizes the conversion of electrical energy frequency ω1 to frequency ω2, and at the same time, the output end of the converter returns, returns to the intermediate coil again to realize energy return, and then transmits electrical energy to the receiving coil, and is connected in series at both ends of the relay-end coil.

[0008] The topological feature of energy reflux is formed by connecting an impedance device in series with the power sending coil, the power relay coil, and the power receiving coil of electric energy, and combining with an AC / AC power converter, which undertakes the functions of blocking electric energy in different frequency forms and guiding the flow direction of electric energy transmission;

[0009] Figure 1 The shown system structure includes the core part of the coupling mechanism, which is composed of three coils: the sending coil L1, the relay coil L2, and the receiving coil L3. Among them, the sending coil uses ω1 as the frequency of the transmitted power, the receiving coil uses ω2 as the frequency of the transmitted power, and the relay coil includes both ω1 and ω2 frequencies. In order to achieve decoupling of different-end frequencies and ensure the correct transmission direction, impedance Z1, Z2, Z3, and Z4 are connected in series at the power sending end, the power output branch of the relay coil, the power reflux branch of the relay coil, and the power receiving end of the system. While being able to block specific frequency signals to achieve frequency decoupling, this series impedance can also compensate for the reactive power of the system, improving the power factor and transmission efficiency of the system;

[0010] Frequency decoupling is characterized in that impedance devices are connected in series with the power sending coil, the relay coil, and the power receiving coil to isolate and decouple electric energy in different frequency forms.

[0011] The said series impedance device needs to be designed through series and parallel resonance. The parallel resonance design of the parallel structure elements decouples the crosstalk frequency, and the series resonance design of the series-parallel combination elements compensates for the reactive power of each end coil. Description of the Drawings

[0012] Figure 1 : Structure of the cross-media multi-frequency wireless power transmission system

[0013] Figure 2 : Equivalent coupling topology of the three-coil coupling mechanism

[0014] Figure 3 : Resonance and wave-blocking impedance structure

[0015] Figure 4 : Topological structure of the AC-AC power converter Detailed Implementation Manner

[0016] 1. Overall system structure design: The implementation method of wireless power transmission. The system is designed by using the method of magnetic induction wireless power transmission. The power sending coil and the receiving coil are respectively on two different media sides, and the relay coil is at the interface of the two media, receiving the power from the sending end and sending the power to the receiving end. The existence of wave-blocking and resonant impedance makes the coupling part equivalent to two independent coupling coils, as shown in the appendix Figure 2 shown.

[0017] According to the resonance condition, the capacitance parameters in the impedance satisfy the following relationship:

[0018]

[0019] The input and output satisfy the following relationship:

[0020]

[0021] 2. Compensation method of system reactive power and frequency decoupling design: The series-parallel structure of impedances Z1, Z2, Z3, and Z4 can make the impedance appear capacitive at the corresponding frequency, achieving the compensation of the reactive power of the coil. At the same time, the parallel structure of inductance and capacitance can form a parallel resonance to block specific frequencies. The impedance structure form is as shown in the appendix Figure 3 as shown.

[0022] The power output branches of the transmitting coil and the relay coil transmit energy at frequency ω1. The series impedances Z1 and Z2 can cooperate with the coil to achieve series resonance and can also block the energy signal with frequency ω2. The component parameters satisfy the following relationship:

[0023]

[0024] The power return branch of the relay coil and the receiving coil are in series with impedances Z3 and Z4, satisfying:

[0025]

[0026] 3. Frequency conversion design: The system of the present invention involves energies of multiple frequencies, and the frequency conversion is achieved by adding an AC-AC power converter. A rectifier circuit and an inverter circuit are connected to the intermediate coil end. By first converting the power signal with frequency ω1 into a DC signal and then converting the DC signal into a power signal with frequency ω2, the frequency conversion is realized. The topological structure is as shown in the appendix Figure 4 as shown.

[0027] 4. Design of the energy return method: The present system is designed with three coils to achieve cross-media multi-frequency wireless power transmission. In addition to involving the decoupling of multiple frequencies, ensuring correct energy transmission is also one of the designs of the present system. The present invention receives the energy of the transmitting coil through the relay coil, converts the received electric energy through the AC-AC power converter and continues to feed it into the relay coil, and the relay coil transmits the converted electric energy to the receiving coil, cooperating with the circuit topology to realize the energy return and retransmission.

[0028] Technical effects

[0029] 1. This patent solution proposes a cross-media multi-frequency wireless power transmission system and design method, which improves the defects existing in the single-media single-frequency wireless power transmission method for multi-media application scenarios, expands the single-frequency wireless power transmission to a multi-frequency system, makes the wireless power transmission system more flexible in the face of complex multi-media environments, and achieves better system performance.

[0030] 2. The existence of the relay coil enables the system to balance the system transmission efficiency and transmission power to a greater extent and improve the transmission distance. On the one hand, the addition of the relay coil makes the coupling mechanism a three-coil structure, which can effectively improve the electromagnetic coupling ability compared with the double-coil structure and increase the system's wireless power transmission distance; on the other hand, the structure of the relay coil is flexible, and by adjusting the structure of the relay coil, various parameters of the coil can be changed, the quality factor can be improved, and the transmission efficiency can be enhanced; in addition, by adjusting the relative position of the transmitting coil and the relay coil, the transmission efficiency can be effectively improved and the wireless power transmission capacity can be increased.

[0031] 3. This patent technical solution increases the system operating frequency from one operating frequency to two operating frequencies for the defects of cross-media wireless power transmission, which can match the characteristics of different transmission media and balance the overall transmission power and transmission efficiency of the system. The traditional wireless power transmission system is limited by a single frequency and cannot achieve the optimal solution under multi-objective constraints (cross-media) to improve the overall performance of the system; the multi-frequency system increases the controllable variables and flexibility of the system and can obtain the optimal solution to a greater extent.

Claims

1. An overall structure of a cross-medium multi-frequency wireless power transmission system: The system of the present invention realizes the conversion from a single frequency to a multi-frequency system and the energy retransmission by adding a relay end coil, an AC-AC power converter and an energy return topology, and realizes the decoupling of different frequencies by adding energy storage elements and performing impedance design; The added relay end coil is characterized in that it is composed of a single power sending end coil, a single power relay end coil and a single power receiving end coil, and includes a power sending end coil, a relay end coil and a receiving end coil power compensation circuit; AC-AC power converter features It is composed of a rectifier converter and an inverter converter in cascade, which realizes the frequency change of electric energy and the separation of energy branches with different frequencies, and is connected in series with the two sections of the relay end coil; The energy return topology is characterized by an impedance connected in series with the power sending coil, the power relay coil and the power receiving coil, and combined with an AC / AC power converter, which plays the role of blocking power of different frequencies and guiding the power transmission flow. The impedance device is composed of energy storage elements connected in series and in parallel, connected in series to each end coil side, and plays the role of reactive power compensation for the power sending end coil, the power relay end coil and the power receiving end coil; The series-parallel combination of the energy storage elements is characterized by being composed of inductors and capacitors in parallel and capacitors or inductors in series, and is designed based on the role in the circuit.

2. The realization method of three-coil multi-frequency energy transmission: It is characterized by The separation and transmission of energy in different frequency forms are realized through three coils. The core lies in the separation and processing of electric energy in different frequency forms of the relay end coil and the guidance of the transmission flow direction; The implementation method is to cascade an AC / AC power converter in the relay end coil to achieve the change of the power frequency, connect an impedance in series in the branch of the sending end coil-relay end coil-AC / AC power converter to separate and block the power in different frequency forms, connect an impedance in series in the output end branch of the AC / AC power converter, and connect the relay end coil again to achieve the transmission of power in another frequency form to the power receiving end coil; The implementation method can realize three-coil multi-frequency energy transmission, ensuring that the transmitting end coil and the receiving end coil transmit electric energy in different frequency forms.

3. A frequency decoupling method, characterized in that: Resistors are connected in series with the electric energy sending coil, the relay coil and the receiving coil to decouple electric energy of different frequencies; The impedance device needs to be designed through series-parallel resonance, the parallel structural element parallel resonance design is used to decouple the crosstalk frequency, and the series-parallel combination element series resonance design is used to compensate for the reactive power of each end coil.

Images