Constant-current and constant-voltage wireless power transmission system based on integrated composite compensation topology

Abstract

The invention discloses a constant-current constant-voltage wireless power transmission system based on an integrated composite compensation topology, and belongs to the technical field of wireless power transmission, the constant-current constant-voltage wireless power transmission system comprises a transmitting end and a receiving end, the transmitting end comprises an H-bridge inversion module, a transmitting end controller, a primary side integrated LCCLC composite compensation network and a transmitting coil, and the receiving end comprises a receiving coil, a series compensation network and a full-bridge rectifier module. The compensation inductor L1 in the integrated LCCLC-S composite compensation and the transmitting end coil are coaxially and tightly installed in the same plane, so that the coupling effect between magnet exciting coils is enhanced; the switching between the LCC-S compensation structure and the LC-S compensation structure is realized through switch control; constraint conditions of composite compensation structure parameter design are further given, and the constant current output characteristic and the constant voltage output characteristic of the LC-S compensation state are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless power transmission, and particularly to a constant current and constant voltage wireless power transmission system based on an integrated composite compensation topology. Background Art

[0002] Wireless power transmission technology realizes the conductorless contact transmission of electric energy. Compared with traditional contact power transmission, it gets rid of the bondage of wires and has the advantages of safety, reliability, flexibility, etc. Magnetic coupling WPT technology has been widely studied due to its advantages of high power, high efficiency, and easy implementation, and its research results have been successfully applied in fields such as electric vehicles, underwater power supply, biomedicine, and robots.

[0003] In order to improve the transmission capacity of a wireless power transmission system, it is generally necessary to add a compensation circuit in the system to reduce reactive power, and the constant voltage or constant current output of the system can also be achieved by adding compensation components. A variety of compensation topologies with constant voltage or constant current output have been proposed in the existing research on WPT systems. At present, domestic and foreign scholars have carried out a large number of studies on the constant current and constant voltage output of WPT systems, mainly focusing on two aspects: mode switching control strategies and compensation topology switching schemes. Scholars have proposed a dual-frequency control strategy based on the LCC-LCC compensation topology, which switches between two fixed frequency points to achieve constant current and constant voltage output. However, this method is easily affected by the frequency bifurcation phenomenon, resulting in a decrease in system stability. Some scholars have proposed to adopt a closed-loop control strategy, which performs feedback control based on the relationship between the phase shift angle of the inverter bridge and the current and voltage at the load end. However, this method relies on wireless communication, the control algorithm is complex, and the response speed is slow. Some scholars have also proposed to introduce a parallel DC chopper circuit at the receiving end to achieve constant current and constant voltage output, but this increases the system volume and reduces the transmission efficiency.

[0004] Although the above methods can accurately control the output, they all highly rely on control algorithms, and the system complexity is relatively high. Therefore, a constant current and constant voltage wireless power transmission system based on an integrated composite compensation topology is proposed. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: how to simply achieve constant voltage or constant current output, and a constant current and constant voltage wireless power transmission system based on an integrated composite compensation topology is provided. The switching between the LCC-S compensation and LC-S compensation structures is realized through switch control. This system is not limited by the parameters of the loosely coupled transformer and has a relatively high transmission efficiency at the same time.

[0006] The present invention solves the above technical problem through the following technical solutions. The present invention includes a transmitting end and a receiving end. The transmitting end includes an H-bridge inverter module, a primary integrated LCC\LC composite compensation network, and a transmitting coil; the receiving end includes a receiving coil, a compensation capacitor, and a full-bridge rectification module;

[0007] The wireless power transmission system is powered by a DC power supply, which is connected to an H-bridge inverter module. The H-bridge inverter module outputs high-frequency alternating current as the input of the primary integrated LCC\LC composite compensation network. The primary integrated LCC\LC composite compensation network is connected to a transmitting coil, and the transmitting coil converts the alternating electrical energy into magnetic energy for transmission; the receiving coil and the compensation capacitor form a series resonance circuit to convert the received magnetic energy into alternating electrical energy; the series resonance circuit is connected to a full-bridge rectifier module, and the full-bridge rectifier module converts the alternating electrical energy into DC electrical energy for output.

[0008] Furthermore, the primary integrated LCC\LC composite compensation network is switched by a switch S, and the opening and closing of the switch S are controlled by a transmitter controller.

[0009] Furthermore, the primary integrated LCC\LC composite compensation network includes a compensation inductor L1, a parallel capacitor C1, a series capacitor C2, and a switch S; when the switch S is closed, the compensation inductor L1, the parallel capacitor C1, and the series capacitor C2 form an LCC compensation state; when the switch S is open, the parallel capacitor C1 is disconnected, and the compensation inductor L1 and the series capacitor C1 form an LC compensation state.

[0010] Furthermore, when the switch S is closed, the transmitter operates in the LCC compensation state, and there is mutual inductance between the compensation inductor L1 and the transmitting coil, and they jointly provide magnetic energy for the receiving coil; when the switch S is open, the transmitter operates in the LC compensation state, and the compensation inductor L1 and the transmitting coil are connected in series as a new transmitting coil.

[0011] Furthermore, by designing the parameters of the primary integrated LCC\LC composite compensation network, the constant current output characteristic in the LCC compensation state and the constant voltage output characteristic in the LC compensation state are realized.

[0012] Furthermore, the parameter design needs to satisfy the following constraint equations:

[0013]

[0014] Among them, ω is the first switching angular frequency, that is, the switching angular frequency when the constant current output is in the LCC compensation state, ω * is the second switching angular frequency, that is, the switching angular frequency when the constant voltage output is in the LC compensation state. X0, X1, X2, X3 are the reactances of each branch impedance when operating at the first switching angular frequency, X 12 , X 13 and X 23 are the reactances of each mutual inductance impedance when operating at the first switching angular frequency, is the reactance of each branch impedance when operating at the second switching angular frequency, is the reactance of each mutual inductance impedance when working at the second switching angular frequency, C1 is the value of the parallel capacitor, L1 is the value of the compensation inductor, L2 is the self-inductance value of the transmitting coil, C2 is the value of the series capacitor, L3 is the self-inductance value of the receiving coil, C3 is the value of the compensation capacitor at the receiving end, M 12 is the mutual inductance value between the compensation inductor L1 and the transmitting coil L2, M 13 is the mutual inductance value between the compensation inductor L1 and the receiving coil L3, M 23 is the mutual inductance value between the transmitting coil L2 and the receiving coil L3.

[0015] Furthermore, the constant current output under LCC compensation is as follows:

[0016]

[0017] Among them, I3 is the root mean square value of the fundamental wave of the current flowing into the full-bridge rectifier module at the receiving end, U AB is the root mean square value of the fundamental wave of the AC voltage output by the H-bridge inverter module.

[0018] Furthermore, the constant voltage output under LC compensation is as follows:

[0019]

[0020] Among them, U out is the output voltage value.

[0021] Furthermore, the switch S is a MOSFET power tube and is driven by an isolated drive circuit.

[0022] Furthermore, the compensation inductor L1 and the transmitting coil L2 in the primary integrated LCC\LC composite compensation network are tightly installed coaxially and coplanarly.

[0023] The present invention has the following advantages compared with the prior art: The constant current and constant voltage wireless power transmission system based on the integrated composite compensation topology adopts an integrated LCC\LC-S composite compensation structure and selects the system to work in the LCC-S compensation state or the LC-S compensation state through switch control; by stacking the primary compensation inductor and the transmitting coil, the integrated design reduces the volume of the device; and only one switch needs to be controlled to realize the switching between the constant current and constant voltage modes, and only the system operating frequency needs to be adjusted during the switching process, without complex control algorithms. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the topological structure diagram of the wireless power transmission system with integrated LCC\LC-S composite compensation in the embodiment of the present invention;

[0025] Figure 2It is a schematic diagram of the loosely coupled transformer structure composed of the transmitting coil and the receiving coil in the embodiment of the present invention;

[0026] Figure 3 It is an equivalent circuit diagram of the system working in LCC-S compensation in the embodiment of the present invention;

[0027] Figure 4 It is an equivalent circuit diagram of the system working in LC-S compensation in the embodiment of the present invention. Detailed implementation manners

[0028] The embodiments of the present invention will be described in detail below. These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0029] As Figure 1 shown, this embodiment provides a technical solution: a constant current and constant voltage wireless power transmission system with an integrated LCC / LC-S composite compensation topology, including a transmitting end and a receiving end:

[0030] The transmitting end includes an H-bridge inverter module, a transmitting end controller, a primary integrated LCC\LC composite compensation network, and a transmitting coil; the receiving end includes a receiving coil, a series compensation network, and a full-bridge rectifier module;

[0031] The wireless power transmission system is powered by a DC power supply. The DC power supply is connected to the H-bridge inverter module. The H-bridge inverter module outputs high-frequency alternating current as the input of the primary integrated LCC\LC composite compensation network. The primary integrated LCC\LC composite compensation network is connected to the transmitting coil. The transmitting coil converts the alternating electrical energy into magnetic energy for transmission; the receiving coil and the compensation capacitor form a series resonant circuit to convert the received magnetic energy into alternating electrical energy; the series resonant circuit is connected to the full-bridge rectifier module, and the full-bridge rectifier module converts the alternating electrical energy into DC electrical energy for output;

[0032] The primary integrated LCC\LC composite compensation network includes a compensation inductor L1, a parallel capacitor C1, a series capacitor C2, and a switch S; when the switch S is closed, the compensation inductor L1, the parallel capacitor C1, and the series capacitor C2 form an LCC compensation state; when the switch S is open, the parallel capacitor C1 is disconnected, and the compensation inductor L1 and the series capacitor C1 form an LC compensation state.

[0033] The primary integrated LCC\LC composite compensation network is switched by the switch S. The switch S is a MOSFET power tube and is driven by an isolated drive circuit. The switch S is closed when the system is lightly loaded or the output is open, and the system works in the LCC compensation state; the switch S is open when the system is heavily loaded, and the system works in the LC compensation state.

[0034] In this system, the compensation inductor in the LCC\LC-S composite compensation and the transmitting coil are tightly installed coaxially and coplanarly, as Figure 2 shown in the lower half of Figure 2 , where the inner part is the compensation inductor L1 wound with enameled wire, and the outer part is the transmitting coil L2 wound with enameled wire.

[0035] Figure 3 When the transmitting end controller controls the switch S to close, the transmitting end works in the LCC compensation state. There is mutual inductance between the compensation inductor and the transmitting coil, and they jointly provide magnetic energy for the receiving coil. The equivalent circuit is as shown, and according to KVL (Kirchhoff's voltage law), we can get:

[0036]

[0037] In the above formula:

[0038]

[0039] where X0, X1, X2, X3 represent the reactances of the impedances of each branch, and X 12 , X 13 and X 23 are the reactances of the mutual inductance impedances, and the angular frequency ω = 2πf0;

[0040] From equations (1) and (2), we can get Figure 4 the branch currents I1, I2, I3 in

[0041]

[0042] where the expressions of α and β are:

[0043]

[0044] After ignoring the series equivalent resistance of each inductor coil, the equivalent input impedance of the LCC-S topology is:

[0045]

[0046] In order to reduce the reactive power loss of the WPT system and make the system operate under the zero phase angle condition, we can let and α = 0, that is:

[0047]

[0048] Then we have:

[0049]

[0050] At this time, the root mean square value of the fundamental wave current of I3 is:

[0051]

[0052] It can be concluded that the LCC-S topology can achieve a constant current output independent of the load.

[0053] When the control switch S is disconnected, the transmitting end operates in the LC compensation state, and its equivalent circuit is as Figure 4 shown. According to KVL, we can obtain:

[0054]

[0055] Considering the change of the resonance condition of the LC-S topology, at a frequency of f1 and an angular frequency of ω1, the equivalent impedances Z1 to Z3 are converted to the mutual inductance equivalent impedance Z 12 , Z 13 , Z 23 are respectively converted to and where I a and I b respectively represent the fundamental wave current vectors of the primary resonance branch and the secondary resonance branch.

[0056] I a and I b can be expressed as:

[0057]

[0058] where the expressions of α LC-S and β LC-S are:

[0059]

[0060] Ignoring the effect of the coil series equivalent resistance and when the following relational expressions are satisfied:

[0061]

[0062] I a and I b the root mean square values of the fundamental wave currents are:

[0063]

[0064] Then the equivalent output voltage of the LC-S topology is:

[0065]

[0066] Under the condition of satisfying Equation (12), the output voltage Uout Not affected by the AC equivalent load, the LC-S topology can achieve a constant voltage output independent of the load.

[0067] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A constant current and constant voltage wireless power transmission system based on an integrated composite compensation topology, characterized in that: It includes a transmitting end and a receiving end. The transmitting end includes an H-bridge inverter module, a primary-side integrated LCC\LC composite compensation network and a transmitting coil; the receiving end includes a receiving coil, a compensation capacitor and a full-bridge rectifier module. The wireless power transmission system is powered by a DC power supply, which is connected to an H-bridge inverter module. The H-bridge inverter module outputs high-frequency AC power as the input of the primary-side integrated LCC\LC composite compensation network. The primary-side integrated LCC\LC composite compensation network is connected to the transmitting coil, which converts the alternating electrical energy into magnetic energy for transmission; the receiving coil and the compensation capacitor form a series resonant circuit to convert the received magnetic energy into alternating electrical energy; the series resonant circuit is connected to a full-bridge rectifier module, which converts the alternating electrical energy into DC electrical energy for output.

2. The constant current and constant voltage wireless power transmission system based on the integrated composite compensation topology according to claim 1 is characterized in that: The primary-side integrated LCC\LC composite compensation network is switched by a switch S, and the opening and closing of the switch S is controlled by a transmitter controller.

3. The constant current and constant voltage wireless power transmission system based on the integrated composite compensation topology according to claim 2 is characterized in that: The primary-side integrated LCC\LC composite compensation network includes a compensation inductor L1, a parallel capacitor C1, a series capacitor C2, and a switch S; when the switch S is closed, the compensation inductor L1, the parallel capacitor C1, and the series capacitor C2 form an LCC compensation state; when the switch S is opened, the parallel capacitor C1 is disconnected, and the compensation inductor L1 and the series capacitor C1 form an LC compensation state.

4. The constant current and constant voltage wireless power transmission system based on integrated composite compensation topology according to claim 3 is characterized in that: When the switch S is closed, the transmitting end works in the LCC compensation state, the compensation inductor L1 and the transmitting coil have mutual inductance, and together provide magnetic energy for the receiving coil; when the switch S is opened, the transmitting end works in the LC compensation state, and the compensation inductor L1 is connected in series with the transmitting coil to form a new transmitting end coil.

5. The constant current and constant voltage wireless power transmission system based on integrated composite compensation topology according to claim 4, characterized in that: By designing parameters of the primary-side integrated LCC\LC composite compensation network, a constant current output characteristic in the LCC compensation state and a constant voltage output characteristic in the LC compensation state are achieved.

6. The constant current and constant voltage wireless power transmission system based on integrated composite compensation topology according to claim 5, characterized in that: The parameter design needs to satisfy the following constraint equations: in, ω is the first switching angular frequency, that is, the switching angular frequency when the constant current is output under LCC compensation state, ω * is the second switching angular frequency, i.e., the switching angular frequency when the constant voltage is output under the LC compensation state. X0, X1, X2, and X3 are the reactances of the impedances of each branch when working at the first switching angular frequency. 12 , X 13 and X 23 is the reactance of each mutual inductance impedance when operating at the first switching angular frequency, is the reactance of each branch impedance when operating at the second switching angular frequency, is the reactance of each mutual inductance impedance when working at the second switching angular frequency, C1 is the parallel capacitance value, L1 is the compensation inductance value, L2 is the self-inductance value of the transmitting coil, C2 is the series capacitance value, L3 is the self-inductance value of the receiving coil, C3 is the compensation capacitance value of the receiving end, M 12 To compensate for the mutual inductance between the inductor L1 and the transmitting coil L2, M 13 To compensate for the mutual inductance between the inductor L1 and the receiving coil L3, M 23 is the mutual inductance between the transmitting coil L2 and the receiving coil L3.

7. The constant current and constant voltage wireless power transmission system based on integrated composite compensation topology according to claim 6, characterized in that: The constant current output under LCC compensation state is as follows: Among them, I3 is the fundamental RMS value of the current flowing into the full-bridge rectifier module at the receiving end, U AB It is the fundamental RMS value of the AC voltage output by the H-bridge inverter module.

8. The constant current and constant voltage wireless power transmission system based on integrated composite compensation topology according to claim 7, characterized in that: The constant voltage output under LC compensation state is as follows: Among them, U out is the output voltage value.

9. The constant current and constant voltage wireless power transmission system based on integrated composite compensation topology according to claim 3, characterized in that: The switch S is a MOSFET power tube and is driven by an isolation drive circuit.

10. The constant current and constant voltage wireless power transmission system based on integrated composite compensation topology according to claim 3, characterized in that: The compensation inductor L1 in the primary-side integrated LCC\LC composite compensation network and the transmitting coil L2 are closely installed coaxially and coplanarly.

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