Wireless power transmission system with constant-voltage and constant-current dual-port power supply

Abstract

The invention discloses a wireless electric energy transmission system with a constant-voltage and constant-current dual-port power supply function, relates to the field of wireless electric energy transmission, and aims to solve the problems that in the prior art, the number of components is large, the structure is complex, and the size is large. And the relay coil is integrated in the magnetic coupler by the receiving end, so that the relay coil also serves as a compensation coil. According to the wireless power transmission system, the number of components of the wireless power transmission system is greatly reduced, the overall size and weight are reduced, the cost and the circuit complexity are reduced, and light weight of the wireless power transmission system is facilitated. Furthermore, the coupling coil adopts a DD coil and a Q-type coil, the coil structure is simple, the two kinds of coils are arranged in sequence, natural decoupling can be achieved, the influence of cross coupling is eliminated, and the parameter design complexity is further reduced. And constant-current and constant-voltage output under the condition of zero phase angle can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless power transmission, and particularly to a wireless power transmission system with dual-port power supply of constant voltage and constant current. Background Art

[0002] Traditional single-output wireless power transmission systems are difficult to meet diverse requirements, and unnecessary cross-coupling may affect the output stability of the system or cause the system to deviate from the optimal working efficiency. Therefore, eliminating unnecessary cross-coupling between systems is the key to realizing a stable dual-output wireless power transmission system.

[0003] Traditional methods for eliminating cross-coupling require adding additional components or devices to the original system, such as auxiliary capacitors, shared capacitors, or transformers. These methods use the impedance of the additional components or devices to cancel out the mutual inductance generated by cross-coupling between the coupling coils, thereby achieving circuit decoupling. Due to the use of more components, these methods have no advantages in terms of quality and volume. In addition, the parameter design problem of the derived higher-order compensation network also makes the system design more complex.

[0004] Chinese Patent CN118889712A discloses a multi-functional output wireless charging method based on decoupling design. The technical solution adopted includes a transmitting end, a relay coil, a first receiving end, and a second receiving end. The relay coil includes a series-connected capacitor C2 and coil L2, and is coupled to the coils on the first receiving end and the second receiving end through coil L2. Two compensation capacitors and a compensation coil are also provided on the second receiving end.

[0005] The first receiving end and the second receiving end of this existing patent are independent of each other, and the capacitor C2 on the relay coil and the multiple compensation components on the second receiving end result in a complex overall structure and a large volume. Moreover, it uses two perpendicular solenoid coils and a Q-type coil, increasing the complexity of the magnetic coupler. The outer solenoid coil has a too low quality factor due to its relatively large distance from the ferrite plate.

[0006] Chinese Patent CN115498781A discloses a wireless charging vehicle secondary side current feedback system based on bilateral LCC and coil integration. The technical solution adopted is to use a transmitting circuit containing an LCC compensation network, and both the transmitting end and the receiving end use Q-type coils. On the wireless receiving circuit, it also uses a receiving end containing a secondary side LCC compensation network.

[0007] This existing patent also adopts a relatively complex compensation structure, resulting in a large number of components and a large volume. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the existing defects and provide a wireless power transmission system with dual-port power supply of constant voltage and constant current, which can effectively solve the problems in the background technology.

[0009] To achieve the above object, the present invention discloses a wireless power transmission system with dual-port power supply of constant voltage and constant current. The technical solution adopted is that it includes a transmitting end and a relay coil. The transmitting end is coupled with a first receiving end. The transmitting end includes a coil L P , and there is a coil L S and a compensation capacitor C2 in the first receiving end. The first receiving end is connected to the relay coil L1. The coil L S , and the relay coil L1 are both connected in parallel with the compensation capacitor C2. The coil L P and the coil L S are directly coupled. The relay coil L1 is coupled with a second receiving end. The second receiving end includes a coil L2 and a compensation capacitor C3. The coil L2 is directly coupled with the coil L1, and after the coil L2 and the compensation capacitor C3 are connected in series, they are connected to a second full-bridge rectifier circuit. The second full-bridge rectifier circuit is connected in parallel with a filter capacitor C f2 , and the filter capacitor C f2 is connected in parallel with a load equivalent resistance R B2 .

[0010] As a preferred technical solution of the present application, both the coil L P and the coil L S adopt DD coils, and both the coil L2 and the relay coil L1 adopt Q-type coils.

[0011] As a preferred technical solution of the present application, the transmitting end includes an input voltage source U D , the input voltage source U D is connected to a high-frequency inverter, and the high-frequency inverter is connected to a compensation capacitor C1 and the coil L P .

[0012] As a preferred technical solution of the present application, the value of the compensation capacitor C1 is:

[0013]

[0014] The value of the compensation capacitor C2 is

[0015]

[0016] The value of the compensation capacitor C3 is

[0017]

[0018] Among them, ω is the resonant angular frequency, and M is the mutual inductance between the transmitting end and the first receiving end.

[0019] As a preferred technical solution of the present application, the coil L of the transmitting end P is integrated on the ferrite plate of the transmitting end; the coil L of the first receiving end S and the relay coil L1 are both integrated on the ferrite plate of the first receiving end, and the coil L S and the relay coil L1 are located on the upper and lower sides of the ferrite plate of the first receiving end; the coil L2 of the second receiving end is integrated on the ferrite plate of the second receiving end.

[0020] As a preferred technical solution of the present application, the compensation capacitor C2 of the first receiving end and the relay coil L1 are both connected to a first full-bridge rectifier circuit, and the first full-bridge rectifier circuit is connected in parallel with a filter capacitor C f1 , and the filter capacitor C f1 is connected in parallel with a load equivalent resistance R B1 .

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: By adopting a series compensation structure at the transmitting end and compensating through a parallel compensation capacitor C2 at the receiving end part, the compensation capacitor C2 is connected in parallel with the coil L1, and the coil L1 serves as the compensation coil of the first receiving end and also acts as the transmitting end facing the second receiving end. Thus, the number of components in the wireless power transmission system is significantly reduced, the overall volume and weight are decreased, the cost and circuit complexity are lowered, which is beneficial to the lightweight of the wireless power transmission system. Further, the coupling coils adopt DD coils and Q-type coils. The coil structure is simple, and the two coils are arranged in sequence, which can achieve natural decoupling and eliminate the influence of cross-coupling, further reducing the parameter design complexity. Moreover, the present invention can achieve constant current and constant voltage output under zero phase angle conditions.

[0022] Further, the first receiving end and the relay coil L1 are integrated on the ferrite plate of the first receiving end, ensuring a small distance between the coil and the ferrite, which not only improves the space utilization rate but also can obtain a high quality factor. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is the magnetic flux distribution diagram of the DD coil and the Q-type coil of the present invention;

[0024] Figure 2 is the schematic diagram of the magnetic coupler of the present invention Figure 1 ;

[0025] Figure 3 is the schematic diagram of the magnetic coupler of the present invention Figure 2 ;

[0026] Figure 4Magnetic coupling schematic diagram of the magnetic coupler of the present invention;

[0027] Figure 5 Circuit schematic diagram of the present invention;

[0028] Figure 6 Equivalent circuit diagram of the present invention;

[0029] Figure 7 Output current I of the present invention under different load conditions B1 Swept frequency curve graph;

[0030] Figure 8 Output voltage U of the present invention under different load conditions B2 Swept frequency curve graph;

[0031] Figure 9 Swept frequency curve graph of the input impedance angle of the present invention under different load conditions;

[0032] Figure 10 Graph of the changes in the output voltage and current of the inverter, the output current of the first receiving end, and the output voltage of the second receiving end of the present invention under different load conditions;

[0033] Figure 11 Overall efficiency schematic diagram of the present invention under different load conditions. Specific implementation manner

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0035] Embodiment 1

[0036] As Figures 1 to 6 shown, the present invention discloses a wireless power transmission system with dual-port power supply of constant voltage and constant current. The technical solution adopted is that, as Figure 5 shown, it includes a transmitting end and a receiving end. The transmitting end has a DC input voltage source U D , and the DC input voltage source U D is connected to a high-frequency inverter composed of four MOS transistors. The high-frequency inverter includes MOS transistor Q1 and MOS transistor Q2. MOS transistor Q1 is connected in series with MOS transistor Q3, and MOS transistor Q2 is connected in series with MOS transistor Q4. MOS transistor Q1, MOS transistor Q3 are connected in parallel with MOS transistor Q2, MOS transistor Q4. The transmitting end also has a series compensation circuit, including a series-connected compensation capacitor C1 and a transmitting coil L P, the front end of the compensation capacitor C1 is connected between the MOS transistor Q1 and the MOS transistor Q3, and the rear end of the transmitting coil L P is connected between the MOS transistor Q2 and the MOS transistor Q4. The transmitting coil L P is a D-type coil and is arranged on the bottom surface of the transmitting end ferrite plate.

[0037] The receiving end has a first receiving end and a second receiving end. The first receiving end includes a first receiving coil L in the D-type coil configuration S , the transmitting coil L P and the first receiving coil L S are directly coupled to form a DD coil. The first receiving coil L S is connected in series with a compensation capacitor C2. A relay coil L1 is connected in parallel with the compensation capacitor C2. The relay coil L1 is a Q-type coil. A first full-bridge rectifier circuit is connected between the compensation capacitor C2 and the relay coil L1. The first full-bridge rectifier circuit includes a diode D1 and a diode D2. The diode D1 is connected in series with a diode D3, and the diode D2 is connected in series with a diode D4. The diode D1, diode D3 are in parallel with the diode D2, diode D4. The end of the relay coil L1 is connected to the output end between the diode D1 and the diode D3 of the first full-bridge rectifier circuit, and the end of the compensation capacitor C2 is connected to the output end between the diode D2 and the diode D4. A filter capacitor C f1 is also connected in parallel to the first full-bridge rectifier circuit. The filter capacitor C f1 is connected in parallel with a load equivalent resistance R B1 . The first receiving coil L S is integrated on the top surface of the first receiving end ferrite plate and is opposite to and directly coupled to the transmitting coil L P . The relay coil L1 is integrated on the bottom surface of the first receiving end ferrite plate.

[0038] The relay coil L1 not only has a compensation function for the first receiving end but also has a transmitting function for the second receiving end. The second receiving end includes a second receiving coil L2 in the Q-type coil configuration. The second receiving coil L2 is connected in series with a compensation capacitor C3. A second full-bridge rectifier circuit is connected between the rear end of the compensation capacitor C3 and the front end of the second receiving coil L2. The second full-bridge rectifier circuit includes a diode D5 and a diode D6. The diode D5 is connected in series with a diode D7, and the diode D6 is connected in series with a diode D8. The diode D5, diode D7 are in parallel with the diode D6, diode D8. The end of the compensation capacitor C3 is connected to the output end between the diode D5 and the diode D7 of the second full-bridge rectifier circuit, and the end of the second receiving coil L2 is connected to the output end between the diode D6 and the diode D8. A filter capacitor C f2 is also connected in parallel to the second full-bridge rectifier circuit. The filter capacitor C f2 is connected in parallel with a load equivalent resistance R B2. The second receiving coil L2 is integrated on the top surface of the second receiving end ferrite plate, opposite to the relay coil L1 and directly coupled.

[0039] The magnetic flux distributions of the DD coil (transmitting coil L P and the first receiving coil L S ) and the Q-type coil (relay coil L1 and second receiving coil L2) are as Figure 1 shown. The DD coil is composed of two D-type coils connected in series in opposite directions. When the exciting current increases, the current directions of the two D-type coils are opposite. Therefore, the magnetic flux directions generated by the two D-type coils are opposite. In addition, in a magnetic field, the magnetic flux ψ caused by one coil being excited and passing through another coil can be expressed as:

[0040]

[0041] where B is the magnetic field strength of the DD coil, and S is the surface area of the DD coil perpendicular to the magnetic field direction. From the above analysis, it can be seen that the two parts of the magnetic flux generated by the DD coil cancel each other out when flowing through the Q-type coil. Similarly, the magnetic fluxes from the Q-type coil cancel each other out when flowing through the DD coil. At this time, the mutual inductance between the DD coil and the Q-type coil is approximately zero, and the two coils are naturally decoupled. The relationship between the mutual inductance M and the magnetic flux ψ between the DD coil and the Q-type coil can be expressed as:

[0042]

[0043] As Figure 2 、 Figure 3 shown, the transmitting end coil L P and the first receiving coil L S in this embodiment are both composed of DD coils, the relay coil L1 and the second receiving coil L2 are both composed of Q-type coils, and the first receiving coil L s and the relay coil L1 are integrated on the first receiving end ferrite plate, which can eliminate unnecessary cross-coupling in the dual-output wireless power transmission system. The magnetic coupling principle diagram of the magnetic coupler is as Figure 4 shown, and M1, M2, M3, M4, M5, and M6 are the mutual inductances between L P and L S , L1 and L2, L P and L2, L P and L1, L S and L2, and L S and L1 respectively. Since the mutual inductance between the DD coil and the Q-type coil is approximately zero, it is obtained that the mutual inductances M3, M4, M5, and M6 are approximately zero. Therefore, the magnetic coupler proposed by the present invention can eliminate the influence of unnecessary cross-coupling.

[0044] The phasor U of the AC output voltage of the high-frequency inverter inThe root mean square value and the system DC input voltage U D The relationship can be expressed as:

[0045]

[0046] Approximately, I O1 and U O2 The root mean square values and I B1 and U B2 The relationship between them can be expressed as:

[0047]

[0048] To simplify the calculation, Figure 6 The impedance expression in it is:

[0049]

[0050] The equivalent circuit diagram of this system is as shown in Figure 6 shown. For the convenience of analysis, the internal resistance of each coil in the system is ignored. According to Kirchhoff's voltage law, the voltages between each loop can be expressed as:

[0051]

[0052] The current phasor I at present P 、I O1 , and the voltage phasor U O2 The expressions can be expressed as:

[0053]

[0054] Among them, the expressions of A and B can be expressed as:

[0055]

[0056] It can be seen from Equation (5), Equation (7), and Equation (8) that to ensure that I O1 、U O2 are independent of R L1 、R L2 , A should be set to zero, that is:

[0057]

[0058] Substitute Equation (8) and Equation (9) into Equation (7), then the input current phasor I P , the output current phasor I O1 , and the output voltage phasor U O2 can be expressed as:

[0059]

[0060] As can be seen from Equation (10), the output current at the first receiving end and the output voltage at the second receiving end of the system are not affected by the load R B1 and R B2 variations. Additionally, to avoid losses caused by reactive circulating currents, the system should operate at a zero phase angle, i.e., the imaginary part of the input impedance Z in should be zero. Substituting Equation (8) into Equation (10), the constraint condition for the system to operate at a zero phase angle can be expressed as:

[0061] Z2Z3 + Z2Z4 + Z3Z4 = 0 (11)

[0062] Therefore, Z in can be expressed by the equation as:

[0063]

[0064] As can be seen from Equation (10) and Equation (12), the output current at the first receiving end and the output voltage at the second receiving end of the system are independent of the load. In addition, Z in exhibits pure resistance, i.e., the system can achieve zero phase angle operation. According to the above analysis, when the system satisfies Equation (9) and Equation (11), the system can achieve load-independent CC output and CV output under zero phase angle conditions.

[0065] Therefore, substituting Equation (6) into Equation (10) and Equation (12), the expressions for the compensation capacitors C1, C2, C3 can be expressed as:

[0066]

[0067] Verify this embodiment through simulation experiments:

[0068] Obtain the sweep frequency curves of the output current I B1 , output voltage U B2 and input impedance angle under different load conditions through matlab simulation, as shown in Figure 7 , Figure 8 , Figure 9 . It can be clearly seen from the figure that at a working frequency of 85 kHz, the first receiving end and the second receiving end can obtain constant current output and constant voltage output respectively. In addition, the system can achieve zero phase angle operation. The above simulation results prove the feasibility of the basic working characteristics of the dual-output wireless power transfer system of this embodiment.

[0069] As shown in Figure 10 , Figure 10 (a), the load resistors R B1 at the first receiving end and R B2 at the second receiving end are 5Ω and 30Ω respectively. Figure 10 (b), RB1 and R B2 are 10 Ω and 60 Ω respectively. Obviously, under different load conditions, this embodiment can achieve a constant current output of 2.5 A and a constant voltage output of 72 V. In addition, under different combinations of R B1 and R B2 , the phase difference between I P and U in is always zero, which means that the proposed system can perform zero phase angle operation.

[0070] The overall efficiency of the system under different load conditions is as Figure 11 shown. This embodiment achieves a maximum efficiency of 92.1% under the conditions that R B1 is 17 Ω and R B2 is 55 Ω.

[0071] The circuit connection involved in the present invention is a common means adopted by those skilled in the art and can obtain technical inspiration through a limited number of experiments, belonging to common general knowledge.

[0072] The components not described in detail in this article are prior art.

[0073] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A wireless power transmission system with dual-port power supply of constant voltage and constant current, characterized in that: It includes a transmitting end and a relay coil. The transmitting end is coupled with a first receiving end, and the transmitting end includes coil L P , and there is coil L in the first receiving end S and compensation capacitor C2. The first receiving end is connected to the relay coil L1. Coil L S and the relay coil L1 are both connected in parallel with the compensation capacitor C2. Coil L P and coil L S are directly coupled. The relay coil L1 is coupled with a second receiving end. The second receiving end includes coil L2 and compensation capacitor C3. Coil L2 is directly coupled with coil L1, and coil L and the compensation capacitor C3 are connected in series and then connected to a second full-bridge rectifier circuit. The second full-bridge rectifier circuit is connected in parallel with a filter capacitor C f2 , and the filter capacitor C f2 is connected in parallel with a load equivalent resistance R B2 .

2. The wireless power transmission system with dual-port power supply of constant voltage and constant current according to claim 1, characterized in that: The coil L P and the coil L S both adopt DD coils, and both the coil L2 and the relay coil L1 adopt Q-type coils.

3. The wireless power transmission system with dual-port power supply of constant voltage and constant current according to claim 1 or 2, characterized in that: The transmitting end includes an input voltage source U D , the input voltage source U D is connected to a high-frequency inverter, and the high-frequency inverter is connected to a compensation capacitor C1 and the coil L P .

4. The wireless power transmission system with dual-port power supply of constant voltage and constant current according to claim 3, wherein The value of the compensation capacitor C1 is: The value of the compensation capacitor C2 is The value of the compensation capacitor C3 is Where ω is the resonant angular frequency and M1 is the mutual inductance between the transmitting end and the first receiving end.

5. The wireless power transmission system with dual-port power supply of constant voltage and constant current according to claim 2, characterized in that: The coil L of the transmitting end P is integrated on the ferrite plate of the transmitting end; The coil L S of the first receiving end and the relay coil L1 are both integrated on the ferrite plate of the first receiving end, and the coil L S and the relay coil L are located on the upper and lower sides of the ferrite plate of the first receiving end; The coil L2 of the second receiving end is integrated on the ferrite plate of the second receiving end.

6. The wireless power transmission system with dual-port power supply of constant voltage and constant current according to claim 1, characterized in that: The compensation capacitor C2 and the relay coil L1 of the first receiving end are both connected to a first full-bridge rectifier circuit, and the first full-bridge rectifier circuit is connected in parallel with a filter capacitor C f1 , the filter capacitor C f1 is connected in parallel with a load equivalent resistance R B1 .

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