A constant-current constant-voltage output self-switching wireless power transmission system based on voltage doubler rectification

Abstract

The application discloses a constant-current constant-voltage output self-switching wireless power transmission system based on voltage doubling rectification. The system comprises a clamping rectifier bridge, a half-bridge inverter, a voltage doubling rectification circuit, a transmitting coil, a clamping coil, a receiving coil, a primary series compensation capacitor, a secondary parallel compensation capacitor, a secondary series compensation inductor and a clamping circuit compensation capacitor. When the system starts to work, the primary coil current increases with the increase of the load, the clamping coil induced voltage amplitude gradually increases until E / 2, the clamping rectifier bridge starts to be incompletely conducted, and the system behaves as a constant-current output before this time; when the induced voltage amplitude reaches 2 E / π / 2, the clamping rectifier bridge is fully conducted, at this time, the primary coil current is clamped to a constant value, the system input changes from a constant-voltage source to a constant-current source, and the system realizes constant-voltage output. The application can realize constant-current constant-voltage output self-switching without any control, has an open-circuit self-protection function, and has the advantages of few compensation elements and switching devices, high design freedom and the like. In addition, the design also has the effect of improving the system efficiency.

Description

Technical Field

[0001] This invention relates to the field of wireless power transmission technology, specifically to a constant current and constant voltage output self-switching wireless power transmission system based on voltage doubler rectification. Background Technology

[0002] Wireless power transfer (WPT) technology is a technology that transmits electrical energy without physical contact, through magnetic or electric field coupling. Compared to traditional wired power transfer methods, it offers advantages such as reliability, safety, flexibility, and convenience. When applying WPT technology to battery charging, a constant current followed by a constant voltage charging method is typically used. This method reduces charging time and extends battery life. Currently, achieving constant current and constant voltage output mainly involves controlling the system's operating frequency, adding DC-DC auxiliary devices, switching topologies, and phase-shift modulation. However, these methods have several drawbacks. For example, frequency conversion control requires an external power unit, increasing cost and size; topology switching requires AC switches added to the primary or secondary side, which can cause voltage fluctuations during switching, affecting battery life; phase-shift control prevents the inverter from handling large load changes at zero voltage startup, leading to decreased system efficiency and increased electromagnetic interference; and DC-DC control increases system size, making the system bulky and reducing efficiency. To address these issues, this paper proposes a constant-current, constant-voltage output self-switching wireless power transfer system based on voltage doubler rectification. This system requires no control and can achieve two output modes with automatic switching between them. Furthermore, the system design offers high flexibility to adapt to charging batteries of different specifications. The system itself features open-circuit self-protection and has the advantages of requiring fewer compensation components and switching devices. In addition, the use of a voltage doubler rectifier circuit improves system efficiency. Summary of the Invention

[0003] This invention provides a constant current / constant voltage output self-switching wireless power transfer system based on voltage doubler rectification. The technical problem it solves is that it can achieve two output modes without any control and can automatically switch between them. The system design offers high flexibility to adapt to charging batteries of different specifications. It requires fewer hardware components, has open-circuit self-protection, and also improves system efficiency. To achieve the above objectives, this invention provides the following technical solution: The present invention discloses a constant current and constant voltage output self-switching wireless power transmission system based on voltage doubler rectification. The system includes a clamping rectifier bridge, a high-frequency half-bridge inverter, and a voltage doubler rectifier circuit. The system also includes primary-side compensation capacitors. C 1. Transmitting coil L 1. Clamping circuit compensation capacitorC 2. Clamping coil L 2. Receiving coil L 3. Parallel compensation capacitor on the secondary side C 3 and secondary series compensation inductor L 4; The clamping rectifier bridge is connected in parallel with the high-frequency half-bridge inverter, with its input connected to the positive terminal of the DC power supply and its output connected to the negative terminal of the DC power supply. The clamping circuit compensation capacitor... C 2 One end is connected to the output port B of the clamping rectifier bridge, and the other end is connected to the clamping coil. L 2 connected together, the compensation capacitor C One end is connected to the output port A of the high-frequency half-bridge inverter, and the other end is connected to the transmitting coil. L 1 connected, transmitting coil L 1. The other end is connected to the clamping coil. L 2. The other end is connected to the negative terminal of a DC power supply; the transmitting coil L 1 with clamping coil L 2. Integrated on the original side; The series compensation inductor L One end of 4 is connected to the input port C of the secondary-side voltage doubler rectifier circuit, and the other end is connected to the receiving coil. L 3. Compensation capacitor C 3 connected, receiving coil L 3 and compensation capacitor C 3. The other end is connected to the other input port D of the voltage doubler rectifier circuit; the voltage doubler rectifier circuit consists of series diodes. D 3. D 4. Series capacitor C O1 , C O2 The load is connected in parallel. The system's magnetic coupler transmitting coil L 1 with clamping coil L 2. Integrated on the original side, receiving coil L 3 with clamping coil L Decoupling between 2; Furthermore, during system operation, the primary coil current is affected by the load, increasing with the increase of the load. The induced voltage in the clamping coil also increases with the increase of the primary coil current. Initially, due to the small load, the amplitude of the primary coil current is small, resulting in a small induced electromotive force on the clamping coil, not exceeding [the specified value]. E / 2, at this time the clamping rectifier is not conducting, and the system outputs a constant current. When the amplitude of the induced electromotive force generated on the clamping coil is equal to E At / 2, the clamping rectifier begins to conduct. After a transition from constant current to constant voltage, the amplitude of the induced electromotive force generated on the clamping coil is equal to 2. E / π When the clamping rectifier is fully turned on, the primary coil current is clamped to a constant value, the system input changes from a constant voltage source to a constant current source, and the system achieves constant voltage output. Furthermore, when the system is working, if an open circuit fault occurs on the load side, the system will automatically switch to constant voltage mode, which has the function of open circuit self-protection. Furthermore, the system has a transition process from constant current mode to constant voltage mode, and the critical resistance at the constant current / constant voltage critical point is: in, R B,CC The critical point for the end of constant current mode R B,CV To reach the critical point of constant voltage mode, ω is the operating angular frequency of the system. M 1 is the transmitting coil L 1 and receiving coil L Mutual induction between 3 M 2 is the transmitting coil L 1 with clamping coil L Mutual induction between 2. Furthermore, the parameters of the primary and secondary side compensation devices and clamping circuit of the system should meet the following requirements: Beneficial effects Compared to existing technologies, this invention provides a constant current and constant voltage output self-switching wireless power transfer system based on voltage doubler rectification. It can achieve both constant current and constant voltage output modes without any control and can automatically switch between the two modes. Under the condition that the system frequency, magnetic coupler, and input voltage are fixed, it can adapt to charging batteries of different specifications, offering high system design freedom. The system has fewer compensation components and switching devices, and features open-circuit self-protection, further improving system efficiency. Attached Figure Description Figure 1 This is a circuit diagram of a constant current and constant voltage output self-switching wireless power transmission system based on voltage doubler rectification, according to a specific embodiment of the present invention. Figure 2 This is a circuit schematic diagram in constant current output mode in a specific embodiment of the present invention. Figure 3 This is an equivalent circuit diagram in constant current output mode in a specific embodiment of the present invention. Figure 4 This is an equivalent circuit diagram in constant voltage output mode in a specific embodiment of the present invention. Figure 5 This is a specific embodiment of the present invention, showing the voltage and current changes during the charging process. Detailed Implementation The embodiments of the present invention are described in detail below with reference to the accompanying drawings. The embodiments are given for illustrative purposes only and should not be construed as limiting the present invention. The accompanying drawings are for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention. The topology of the constant current and constant voltage output self-switching wireless power transfer system based on voltage doubler rectification described in this invention is as follows: Figure 1 As shown. Among them, E It is the DC power supply voltage input to the system. Q 1. Q 2 refers to the two MOSFETs in the primary-side half-bridge inverter. D 1. D 2 is the clamping diode of the primary-side clamping rectifier bridge, two diodes. D 3. D 4 and two filter capacitors C O1 , C O2 This forms a secondary-side voltage doubler rectifier circuit. L 1. L 2 and L 3 represents the self-inductance of the primary coil, clamping coil, and secondary coil, respectively. C 1 is a primary-side series compensation capacitor. C 3 and L 4 represents the parallel compensation capacitor and the series compensation inductor on the secondary side, respectively. C 2 is an auxiliary coil series compensation capacitor. M 1. M 2. M 3 represents the mutual inductance between each pair of the primary coil, secondary coil, and auxiliary coil in this design. M 3 = 0. U AN , I 1 represents the output voltage and current of the primary-side inverter, respectively. U CD , I 4 represents the input voltage and current of the secondary-side voltage doubler rectifier circuit, respectively. U BN , I 2 represents the input voltage and current of the auxiliary circuit clamping rectifier bridge, respectively. I 3 represents the secondary side coil current. R B It is the battery's equivalent resistance, defined as the output voltage. UB With output current I B The ratio, R eq It is the equivalent AC battery resistance. Equivalent AC battery resistance R eq Inverter output voltage U AN RMS values ​​and RMS values ​​of input voltage and current of voltage doubler rectifier U CD and I 4 can be represented as (1) Depend on Figure 1 It can be seen that when the system is working, the half-bridge inverter will receive a DC input voltage. E Chopper to high-frequency square wave voltage U AN , D This represents the inverter's duty cycle. U AN fundamental component of U AN1 for: (2) U BN Connected directly to the clamping rectifier bridge E , U BN It is also a high-frequency square wave voltage, its fundamental component U BN1 for: (3) Set auxiliary coil compensation capacitor C 2. Compensation is performed on the auxiliary coil at the resonant frequency, i.e., the compensation capacitor of the auxiliary circuit satisfies: (4) When the charging system charges the battery, it first enters the constant current charging stage. At this time, the induced voltage amplitude of the clamping coil is less than... E / 2, the primary-side clamping rectifier bridge diodes are reverse-biased and cut off; therefore, the clamping circuit does not work. I 2=0. Its system equivalent circuit structure is as follows: Figure 2 As shown, to simplify the analysis, an equivalent circuit diagram is given, such as... Figure 3 As shown. According to Kirchhoff's voltage law, the following equation can be obtained: (5) That is, the current phasors of each loop are (6) For simplicity, symbols X and Y are introduced in equation (6), which are respectively represented as (7) In order for the system to achieve load-independent CC output, I The value of 4 should not be affected by the AC equivalent resistance. R The effect of eq. From equation (6), it can be seen that setting X to zero will yield CC output. That is, the condition for CC output is... (8) Furthermore, the system's input impedance can be obtained from equation (6). Z in As shown in equation (8). (9) To avoid system losses due to reactive power circulating current, the system should always operate at zero voltage (ZPA). Z in At the operating angular frequency ω It should be a pure resistance. That is, the condition for the system to operate under ZPA is... (10) According to formulas (7) and (9), Z in Further derivation as (11) Substituting equations (7) and (9) into equation (5), the current phasor for each loop can be simplified to: (12) Based on formula (12), the transconductance can be derived. G ui for (13) Obviously, from formulas (11) and (12), it can be concluded that the system can not only achieve CC output independent of the load, but also make the system work under ZPA conditions. As the system operates, the induced electromotive force generated on the auxiliary coil U BN Amplitude equals 2 E / π At this time, the auxiliary circuit half-bridge rectifier is fully turned on, and its system equivalent circuit structure is as follows: Figure 1 As shown, to simplify the analysis, an equivalent circuit diagram is given, such as... Figure 4 As shown. According to Kirchhoff's voltage law, the following equation can be obtained: (14) Due to the clamping diode, the primary-side current is constrained to a constant value. This is equivalent to the drive power supply being converted into a constant current source, and the primary-side current... I 1 is (15) Substituting equations (8), (10), and (15) into equation (14) yields... (16) This means the output voltage is unaffected by the load. Because the phase of the primary coil current does not change during system operation, it is simply clamped to a constant value, which is the same as in constant current mode. In other words, the system achieves constant voltage output while... U AN and I 1. In phase, meaning the system implements ZPA operation. During the constant current phase, due to R B It is gradually increasing. I As the amplitude gradually increases, the amplitude of the induced electromotive force generated on the auxiliary coil gradually increases until the auxiliary coil clamps the rectifier bridge voltage. U BN Meet the conditions (17) When the above equation is satisfied... D 1,2 The rectifier bridge begins to conduct. I If 2 is not 0, then the CC charging condition will no longer be satisfied. According to equations (1), (5), and (12), the critical load for CC mode is... (18) when R B < R B,CC At that time, the system is in CC mode. R B ≥ R B,CC At that time, the clamping rectifier bridge section is turned on, and as... R B The amplitude continues to increase. U BN It also increases until (19) At this time, the diode in the auxiliary coil rectifier bridge D 1,2 With the circuit fully turned on, combining equations (14), (15), and (16), we obtain the critical resistance for the converter to enter CV mode as follows: (20) Figure 5The converter is given with load R B The entire charging process. In summary, the present invention provides a constant current and constant voltage output self-switching wireless power transfer system based on voltage doubler rectification. Without any control, the system achieves constant current and constant voltage output under ZPA operating conditions and can automatically switch between constant current and constant voltage modes. Given a fixed system frequency, magnetic coupler, and input voltage, the output voltage and current values ​​can be changed by adjusting system parameters, adapting to charging various battery specifications. The system offers greater design freedom, and the use of a voltage doubler rectification circuit also improves system efficiency. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any simple modifications, equivalent transformations and alterations within the technical solutions and principles of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A constant current and constant voltage output self-switching wireless power transfer system based on voltage multiplier rectification, characterized in that, The system consists of a clamping rectifier bridge ( D 1. D 2) Half-bridge inverter ( Q 1. Q 2) Primary-side compensation capacitor C 1. Transmitting coil L 1. Clamping circuit compensation capacitor C 2. Clamping coil L 2. Forms the primary side; receiving coil L 3. Secondary-side compensation capacitor C 3. Secondary-side compensating inductor L 4 and voltage doubler rectifier circuit ( D 3. D 4. C O1 , C O2 ) constitutes the secondary side. The clamping rectifier bridge on the primary side is connected in parallel with the half-bridge inverter, and the clamping rectifier bridge is connected in parallel with the clamping circuit compensation capacitor. C 2 and clamping coil L 2 in series; the transmitting coil L 1 with clamping coil L 2. Integrated on the original side. The half-bridge inverter on the secondary side and the compensation capacitor on the primary side C 1 and transmitting coil L 1. The receiving coil is connected in series. L 3 and secondary side compensation capacitor C 3 series and parallel secondary compensation inductors L 4 are connected in series to the input ports C and D of a voltage doubler rectifier circuit, which consists of series diodes. D 3. D 4. Series capacitor C O1 , C O2 The load is connected in parallel.

2. The constant current and constant voltage output self-switching wireless power transmission system based on voltage doubler rectification according to claim 1, characterized in that... transmitting coil L 1 with clamping coil L 2. Integrated on the primary side, receiving coil L 3 with clamping coil L Decoupled between 2.

3. The constant current and constant voltage output self-switching wireless power transmission system based on voltage doubler rectification according to claim 1, characterized in that... The primary winding current of the system increases with the increase of the load, and the induced voltage of the clamping coil also increases with the increase of the primary winding current. When the amplitude of the induced voltage of the clamping coil increases to... E At / 2, the clamping rectifier bridge begins to conduct incompletely; before this, the system exhibits constant current output. When the induced voltage amplitude reaches 2... E / π When the clamping rectifier bridge is fully turned on, the primary coil current is clamped to a constant value, the system input changes from a constant voltage source to a constant current source, and the system achieves constant voltage output.

4. The constant current and constant voltage output self-switching wireless power transmission system based on voltage doubler rectification according to claim 1, characterized in that... The system has an open-circuit self-protection function. When an open-circuit fault occurs on the load side, the system will automatically switch to constant voltage mode to achieve the protection function.

5. The constant current and constant voltage output self-switching wireless power transmission system based on voltage doubler rectification according to claim 1, characterized in that... The system has only 4 compensation components, 2 MOSFETs, and 4 diodes, making it simple in structure and requiring minimal hardware.

6. The constant current and constant voltage output self-switching wireless power transmission system based on voltage doubler rectification according to claim 1, characterized in that... Given a fixed system frequency, magnetic coupler, and input voltage, the output voltage and current values ​​of the system can be changed by adjusting the system parameters, allowing for greater design freedom.

7. The constant current and constant voltage output self-switching wireless power transmission system based on voltage doubler rectification according to claim 1, characterized in that... Using a voltage doubler rectifier circuit also improves system efficiency.

8. A constant current and constant voltage output self-switching wireless power transmission system based on voltage doubler rectification according to claim 3, characterized in that... The system has a transition process from constant current mode to constant voltage mode. The critical resistance at the constant current / constant voltage critical point is: Where ω is the operating angular frequency of the system. M 1 is the transmitting coil L 1 with receiving coil L Mutual induction between 3 M 2 is the transmitting coil L 1 with clamping coil L Mutual induction between 2.

9. A constant current and constant voltage output self-switching wireless power transmission system based on voltage doubler rectification according to claim 3, characterized in that... The parameters of the primary and secondary side compensation devices and the clamping circuit should meet the following requirements:

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