Wireless power transmission system based on coupling inductor secondary side hybrid self-switching

Abstract

The invention discloses a wireless electric energy transmission system based on coupling inductor secondary side hybrid self-switching, and the wireless electric energy transmission system carries out switching through a secondary side, can achieve constant current-constant voltage output, and can effectively cope with various abnormal working conditions in the charging process. The system is composed of four switching tubes, four diodes, four high-frequency capacitors, two resonant inductors, two alternating-current switches and two sets of wireless coils, wherein each alternating-current switch is composed of two MOSFETs which are reversely connected in series. A receiving end main circuit has two working modes according to different combinations of working states of an alternating current switch, an Ls1 is switched out of the circuit, and a system enters a constant current mode of LCC-LCC topology; and the Ls1 is switched into the circuit, and the system enters a constant voltage mode of the LCC-S topology. And the secondary side switching compensation inductor Ls1 and the secondary side compensation inductor L2 are combined to form a coupling inductor with a center tap. Finally, the invention provides a compensation parameter calculation method of the wireless power transmission system based on coupling inductor secondary side hybrid self-switching.

Description

Technical Field

[0001] This invention relates to the field of wireless power transmission, and more specifically, to a wireless power transmission system network topology based on hybrid self-switching of coupled inductor secondary sides. Background Technology

[0002] Over the past few years, wireless power transfer (WPT) technology has gradually moved from theoretical research to commercial applications, particularly in consumer electronics, medical devices, and electric vehicles. This technology transfers energy through electromagnetic fields, eliminating the need for wires in traditional charging methods, thus improving ease of use and safety. However, with the expansion of its application scope, WPT systems face increasing technical challenges, especially in terms of efficiency, stability, and adaptability to different charging needs. Traditional wireless power transfer systems (WPT) face several technical limitations in design and implementation, primarily due to their fixed topology and parameter configuration. This fixed nature often results in poor performance when encountering changing charging environments or different charging demands. Another important issue is the system's responsiveness to abnormal operating conditions. Traditional WPT systems are often inflexible in handling sudden load changes, electrical noise, and power fluctuations. These abnormal conditions can lead to short-term overload or underload, causing unstable output power and potentially even short circuits or damage to the system. To address these issues and explore more flexible and efficient WPT system designs, especially those capable of automatically adapting to different operating conditions, this paper proposes a wireless power transfer system based on hybrid self-switching of the coupled inductor secondary side. This system incorporates a self-switching mechanism, enabling automatic switching between constant current and constant voltage modes to adapt to varying charging demands and abnormal operating conditions, while maintaining high efficiency and stable output. The innovation of this technology lies in its composite topology design, utilizing a coupled inductor with a center tap. This design achieves constant current and constant voltage output without adding active components, significantly improving the overall system performance and reliability. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a wireless power transfer system based on hybrid self-switching of the secondary side of a coupled inductor. By switching the secondary side, the system can not only achieve constant current-constant voltage output, but also effectively cope with various abnormal operating conditions during the charging process, laying a theoretical and practical foundation for the widespread application of wireless charging.

[0004] The wireless power transfer system based on coupled inductor hybrid self-switching is connected in that it includes a DC power module V. inThe circuit consists of: switching transistors Q1-Q4, primary-side compensation inductor L1, primary-side parallel compensation capacitor C1, primary-side series compensation capacitor Cp, primary-side transmitting coil Lp, secondary-side compensation inductor L2, secondary-side parallel compensation capacitor C2, secondary-side series compensation capacitor Cs, secondary-side receiving coil Ls, AC switches S1 and S2, secondary-side switching compensation inductor Ls1, diodes D1-D4, filter capacitor Co, and load Ro. One end of the secondary coil Ls is connected to the secondary-side series compensation capacitor Cs and AC switch S1. The secondary-side parallel compensation capacitor C2 is connected to the secondary-side compensation inductor L2, the secondary-side series compensation capacitor Cs, AC switch S1, AC switch S2, and the secondary-side switching compensation inductor Ls1. The anode of diode D1 is connected to the secondary-side compensation inductor L2 and the secondary-side switching compensation inductor Ls1. The anode of diode D4 is connected to the other end of AC switch S1 and the secondary coil Ls.

[0005] The invention of the wireless power transmission system based on coupled inductor hybrid self-switching lies in the fact that the secondary-side switching compensation inductor Ls1 and the secondary-side compensation inductor L2 together form a coupled inductor with a center tap. The invention of the coupled inductor lies in the fact that the coupled inductor is connected at a single common node, with one end of the same name closer to the common node and the other farther away.

[0006] The invention of the wireless power transfer system based on coupled inductor hybrid self-switching lies in that the receiver's main circuit has two operating modes depending on the different combinations of the operating states of switches S1 to S2. When switches S1 and S2 are on or off, they control the switching in or out of Ls1. When S1 is on and S2 is off, Ls1 switches out of the circuit, and the system enters the constant current mode of the LCC-LCC topology; when S1 is off and S2 is on, Ls1 switches in, and the system enters the constant voltage mode of the LCC-S topology.

[0007] The wireless power transfer system based on coupled inductor hybrid self-switching is invented by controlling the turn-on and turn-off sequence of switching transistors S1 to S2 to achieve low-voltage and current stress switching: First, the constant voltage / constant current switching action signal is detected. If a rising edge and a falling edge are detected, it indicates that the system is about to switch from constant voltage to constant current. Then, the flow direction of IC2 is detected. When IC2 flows in the reverse direction, i.e., when the current flows through the anti-parallel body diodes in VT1 and VT2, it is determined to be reverse time, VT1 and VT2 are turned off, and VT3 and VT4 are turned on, switching from constant current to constant voltage. When IC2 flows in the reverse direction, i.e., when the current flows through the anti-parallel body diodes in VT3 and VT4, it is determined to be reverse time, VT3 and VT4 are turned off, and VT1 and VT2 are turned on, switching from constant voltage to constant current. The constant voltage and constant current states can be switched smoothly without generating high voltage and high current surges.

[0008] The invention of the wireless power transfer system based on hybrid self-switching of coupled inductors lies in the following calculation process for its compensation parameters: First, determine the primary transmitting coil Lp, the secondary receiving coil Ls, the coupling coefficient k, the mutual inductance M, the resonant frequency f0, the input voltage Vin, the constant current point I0, and the constant voltage point U0. Then, calculate the primary-side compensation inductance L1 and the secondary-side compensation inductance L2; calculate the primary-side parallel compensation capacitor C1 and the secondary-side parallel compensation capacitor C2; calculate the primary-side series compensation capacitor Cp and the secondary-side series compensation capacitor Cs; finally, calculate the secondary-side switching compensation inductance Ls1.

[0009] Beneficial effects:

[0010] A wireless power transfer system based on hybrid self-switching of the coupled inductor secondary side is presented. By switching on the secondary side, the system can achieve constant current-constant voltage output and effectively cope with various abnormal conditions during charging. An LCC-LCC / S self-switching composite topology is given. Based on the LCC compensated topology, constant voltage / constant current switching is achieved by using a coupled inductor with a center tap, exhibiting stronger stability and reliability under abnormal conditions such as secondary side absence, load short circuit, and load open circuit. Compared with traditional wireless switching topologies, the proposed wireless charging system based on hybrid self-switching of coupled inductors has better constant current-constant voltage output characteristics without adding additional inductors and capacitors, fully meeting the requirements of constant current-constant voltage wireless charging. This lays a theoretical and practical foundation for the widespread application of wireless charging and is conducive to enhancing the competitiveness of wireless power transfer in the charging field. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of a self-switching resonant LCC-LCC / S network topology based on a hybrid switching inductor system.

[0012] Figure 2 This is a schematic diagram of the AC switch for the hybrid self-switching wireless power transmission system.

[0013] Figure 3 This is a schematic diagram of the equivalent circuit of the LCC-LCC system of the hybrid self-switching wireless power transmission system.

[0014] Figure 4 This is a schematic diagram of the equivalent circuit of the LCC-S system of the hybrid self-switching wireless power transmission system.

[0015] Figure 5 The schematic diagram of the Csv impedance equivalent diagram of the hybrid self-switching wireless power transmission system is shown.

[0016] Figure 6 The flowchart shows the constant voltage and constant current switching process of the hybrid self-switching wireless power transmission system. Detailed Implementation

[0017] A resonant topology formed solely by a T-type network cannot achieve constant current and constant voltage output on the secondary side when the primary-side input impedance is purely resistive. Therefore, this invention proposes a network topology based on a hybrid self-switching resonant LCC-LCC / S network with switching inductors, such as... Figure 1 As shown in the figure. Uin is the input DC voltage; Q1 to Q4 are MOSFETs forming the full-bridge inverter circuit; L1, C1, Cp and L2, C2, Cs form the primary and secondary resonant networks respectively; Lp and Ls are the self-inductances on the transmitting and receiving coils respectively; Ls1 is the switching compensation inductor on the receiving coil; D1 to D4 are fast recovery diodes forming the uncontrolled rectifier circuit; S1 and S2 are both AC switches composed of two IGBTs connected in reverse series, their internal structures are as follows... Figure 2 As shown; Co is the filter capacitor; Ro is the equivalent resistance of the battery.

[0018] This invention studies a wireless power transfer system based on hybrid self-switching of the secondary side of a coupled inductor. The receiver's main circuit operates in two modes depending on the different combinations of the operating states of switches S1 and S2. When switches S1 and S2 are on or off, they control the switching in or out of Ls1. When S1 is on and S2 is off, Ls1 switches out of the circuit, and the system enters the constant current charging mode of the LCC-LCC topology. When S1 is off and S2 is on, Ls1 switches in, and the system enters the constant voltage charging mode of the LCC-S topology. The relationship between the switch states and the output modes is shown in Table 1.

[0019] Table 1

[0020]

[0021] The object of this invention is a wireless power transfer system based on hybrid self-switching of the secondary side of a coupled inductor. When S1 is turned on and S2 is turned off, Ls1 switches off the circuit and the system enters the constant current charging mode of the LCC-LCC topology. Figure 3 This is the fundamental equivalent circuit of a WPT system using an LCC-LCC resonant network, where the mutual inductance of the coils in the same plane is very small, which is simplified to 0 here.

[0022] The system has a resonant frequency of f0. When the system parameters satisfy equations (1) and (2), it has a constant current output characteristic.

[0023]

[0024]

[0025] Based on the analysis of the secondary resonant circuit using the T-network topology, the secondary impedance ZLCCin1 is...

[0026]

[0027] Converting the secondary impedance to the primary impedance, we obtain the impedance ZLCCin2 as follows:

[0028]

[0029] Then the input impedance Zin on the primary side is

[0030]

[0031] As can be seen from equation (5), the input impedance Zin of the LCC-LCC type system is purely resistive, which can realize the ZPA characteristic.

[0032] Neglecting the parasitic internal resistances R1 and R2 of the primary and secondary compensation inductors and the parasitic internal resistance RS of the receiving coil, based on Kirchhoff's voltage law, the primary-side output current I1 and the secondary-side output current I0 of the system can be obtained as follows:

[0033]

[0034] As can be seen from equation (7), when the resonant compensation topology of the wireless charging system is of type LCC-LCC, the output current of the system is independent of the magnitude of the equivalent resistance of the load, and it is a constant current output, that is, the system is in CC mode.

[0035] The object of this invention is a wireless power transfer system based on hybrid self-switching of the secondary side of a coupled inductor. When S1 is off and S2 is on, Ls1 is switched into the circuit, and the system enters the constant voltage charging mode of the LCC-S topology. Figure 4 This is the fundamental equivalent circuit of a WPT system using an LCC-S resonant network. Similarly, Req is the equivalent resistance of the rectifier and load circuit, and U0 is the inverter output voltage.

[0036] The system's resonant frequency is f0. When the system parameters satisfy equation (8), it has a constant voltage output characteristic:

[0037]

[0038] Based on the analysis of the secondary resonant circuit using the T-network topology, the secondary impedance ZSin1 is...

[0039]

[0040] By equating the secondary impedance ZSin1 to the primary impedance, we can obtain...

[0041]

[0042] The primary-side input impedance Zin of the system is

[0043]

[0044] As can be seen from equation (11), the input impedance Zin of the LCC-S type system is purely resistive, and the system can achieve ZPA characteristics.

[0045] Based on Kirchhoff's voltage law, the primary resonant current I1 and the system output voltage U0 are respectively...

[0046]

[0047] As can be seen from equation (12), the LCC-S topology can achieve constant voltage characteristics independent of the load under the state of full resonance, and the input impedance Zin has no imaginary part and has ZPA characteristics.

[0048] At this point, the equivalent impedance diagram of Csv is as follows: Figure 5 As shown, the calculation steps are as follows: The series impedance of capacitor C2 and inductor Ls1 is...

[0049]

[0050] The impedance connected in parallel with inductor L2 is

[0051]

[0052] The impedance connected in series with capacitor Cs is

[0053]

[0054] The final total impedance connected in parallel with Ls is

[0055]

[0056] Set the imaginary part of Zfinal to 0 to solve for Lsl.

[0057] Therefore, by rationally designing the primary and secondary side parameters and output power, the LCC-LCC topology and the LCC-S topology can be combined to achieve two-stage constant current-constant voltage charging.

[0058] The object of this invention is a wireless power transfer system based on hybrid self-switching of the secondary side of coupled inductors. By controlling the turn-on and turn-off sequence of the switching transistors S1 to S2, low voltage and current stress switching can be achieved. The stability analysis of the LCC-LCC and LCC-S topologies in response to various abnormal working conditions is summarized in Table 2.

[0059] Table 2

[0060]

[0061] The constant voltage and constant current switching flowchart is as follows: Figure 6As shown, the system first detects the constant voltage / constant current switching signal. If both rising and falling edges are detected, it indicates the system is about to switch between constant voltage and constant current states. Then, the flow direction of IC2 is detected. When IC2 flows in reverse (i.e., current flows through the anti-parallel body diodes in VT1 and VT2), it is determined to be a reverse timeout. VT1 and VT2 are turned off, and VT3 and VT4 are turned on, switching from constant current to constant voltage. Conversely, when IC2 flows in reverse (i.e., current flows through the anti-parallel body diodes in VT3 and VT4), it is determined to be a reverse timeout. VT3 and VT4 are turned off, and VT1 and VT2 are turned on, switching from constant voltage to constant current. The constant voltage / constant current state can be smoothly switched without generating high voltage or high current surges.

Claims

1. A wireless power transfer system based on hybrid self-switching of the secondary side of a coupled inductor, characterized in that, Includes DC power module V in The circuit consists of: switching transistors Q1-Q4, primary-side compensation inductor L1, primary-side parallel compensation capacitor C1, primary-side series compensation capacitor Cp, primary-side transmitting coil Lp, secondary-side compensation inductor L2, secondary-side parallel compensation capacitor C2, secondary-side series compensation capacitor Cs, secondary-side receiving coil Ls, AC switches S1 and S2, secondary-side switching compensation inductor Ls1, diodes D1-D4, filter capacitor Co, and load Ro. One end of the secondary coil Ls is connected to the secondary-side series compensation capacitor Cs and AC switch S1. The secondary-side parallel compensation capacitor C2 is connected to the secondary-side compensation inductor L2, the secondary-side series compensation capacitor Cs, AC switch S1, AC switch S2, and the secondary-side switching compensation inductor Ls1. The anode of diode D1 is connected to the secondary-side compensation inductor L2 and the secondary-side switching compensation inductor Ls1. The anode of diode D4 is connected to AC switch S1 and the other end of the secondary coil Ls.

2. The wireless power transfer system based on coupled inductor hybrid self-switching according to claim 1, characterized in that... The secondary-side switching compensation inductor Ls1 and the secondary-side compensation inductor L2 together form a coupled inductor with a center tap.

3. The coupled inductor according to claim 2, characterized in that, Coupled inductors are connected with a single common node, with one end of the same name close to the common node and the other far away.

4. The wireless power transfer system based on coupled inductor hybrid self-switching according to claim 1, characterized in that, It has constant current characteristics. When S1 is on and S2 is off, Ls1 cuts out the circuit, and the system enters the constant current mode of the LCC-LCC topology. The resonant frequency of the system is f0. When the system has constant current output characteristics, the parameters satisfy the following equation:

5. The wireless power transfer system based on coupled inductor hybrid self-switching according to claim 1, characterized in that, It has constant voltage characteristics. When S1 is off and S2 is on, Ls1 is switched into the circuit, and the system enters the constant voltage mode of the LCC-LCC topology. The resonant frequency of the system is f0. When the system has constant voltage output characteristics, the parameters satisfy the following equation:

6. The wireless power transfer system based on coupled inductor hybrid self-switching according to claim 1, characterized in that, The receiver's main circuit operates in two modes depending on the different combinations of the operating states of switches S1 and S2. When switches S1 and S2 are on or off, they control the switching in or out of Ls1. When S1 is on and S2 is off, Ls1 switches out of the circuit, and the system enters the constant current mode of the LCC-LCC topology; when S1 is off and S2 is on, Ls1 switches in, and the system enters the constant voltage mode of the LCC-S topology.

7. The wireless power transfer system based on coupled inductor hybrid self-switching according to claim 1, characterized in that, By controlling the turn-on and turn-off sequence of switching transistors S1 to S2, low-voltage current stress switching can be achieved. First, the constant voltage / constant current switching action signal is detected. If both rising and falling edges are detected, it indicates that the system is about to switch between constant voltage and constant current states. Then, the flow direction of IC2 is detected. When IC2 flows in reverse, that is, when the current flows through the anti-parallel body diodes in VT1 and VT2, it is determined to be in reverse time. VT1 and VT2 are turned off, and VT3 and VT4 are turned on, switching from constant current to constant voltage. When IC2 flows in reverse, that is, when the current flows through the anti-parallel body diodes in VT3 and VT4, it is determined to be in reverse time. VT3 and VT4 are turned off, and VT1 and VT2 are turned on, switching from constant voltage to constant current.

8. The wireless power transfer system based on coupled inductor hybrid self-switching according to claim 7, characterized in that, The constant voltage and constant current states can be switched smoothly without generating high voltage or high current surges.

9. The wireless power transfer system based on coupled inductor hybrid self-switching according to claim 1, characterized in that, The calculation process for the compensation parameters is as follows: First, determine the primary transmitting coil Lp, the secondary receiving coil Ls, the coupling coefficient k, the mutual inductance M, the resonant frequency f0, the input voltage Vin, the constant current point I0, and the constant voltage point U0. Calculate the primary-side compensating inductance L1 and the secondary-side compensating inductance L2: Calculate the primary-side parallel compensation capacitor C1 and the secondary-side parallel compensation capacitor C2: Calculate the primary-side series compensation capacitor Cp and the secondary-side series compensation capacitor Cs: Finally, the secondary-side switching compensation inductor Ls1 can be obtained through impedance matching.

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