High-fault-tolerance constant-current constant-voltage output self-switching wireless power transmission system

Abstract

The invention belongs to the technical field of wireless power transmission, and particularly relates to a high-fault-tolerance constant-current constant-voltage output self-switching wireless power transmission system. The system comprises a high-frequency inverter, a first rectifier, a second rectifier, a first transmitting coil, a first compensation capacitor, a second transmitting coil, a second compensation capacitor, a parallel compensation capacitor, a first receiving coil, a second receiving coil, a first receiving compensation capacitor and a second receiving compensation capacitor. The system adopts a double-coupling LCC-S topology and resonance compensation parameters, a magnetic coupler of the system adopts a coil structure shaped like a Chinese character'tian 'and a square coil structure, and a transmitting end and a receiving end of the magnetic coupler are kept horizontal and are arranged in parallel; the system can realize switching of constant current or constant voltage output without any active control, has a zero phase angle characteristic during normal work, can realize fault tolerance under common fault conditions such as load open circuit or load short circuit, and also has the advantages of simple compensation parameter configuration, small size, light weight and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of wireless power transmission, and in particular relates to a highly fault-tolerant constant current and constant voltage output self-switching wireless power transmission system. Background Art

[0002] Wireless power transfer (WPT) technology is convenient, safe and reliable. In recent years, it has been a hot research topic in the field of electrical engineering. Domestic and foreign scholars have conducted extensive explorations on its applications in medical treatment, transportation, and energy-carrying communications, and the technology is developing rapidly. Among the applications in many fields, wireless charging of consumer electronics and electric vehicles is undoubtedly one of the most promising application scenarios.

[0003] Generally speaking, in order to eliminate the extra losses caused by reactive current and hard switching, improve transmission efficiency, increase output power, and obtain good output characteristics such as constant current (CC) or constant voltage (CV), WPT systems need to introduce various compensation networks. In addition to the four basic compensation topologies of series-series, series-parallel, parallel-series, and parallel-parallel, commonly used compensation network structures also include various high-order compensation topologies, such as LCC topology.

[0004] However, for WPT systems used in wireless charging, their loads are mainly various types of lithium batteries, and the charging process mostly adopts a staged CC-CV charging method. WPT using the above common compensation topology and resonant compensation parameters only has a single CC or CV output characteristic, which is difficult to meet the requirements of wireless charging of lithium batteries. To address this problem, existing methods mainly include topology switching and control-based methods, but these methods require additional compensation or control elements, increase the complexity and redundancy of the system, and the switching process is relatively complicated, and more ideal solutions still need to be studied and formulated.

[0005] At the same time, since the WPT system using the above-mentioned common compensation topology and resonant compensation parameters has a constant current or constant voltage output characteristic, its load is not allowed to be open or short-circuited accordingly, so there is a fault tolerance problem under load short-circuit or open-circuit conditions. In addition, the WPT system with series compensation at the receiving end will also generate overvoltage and overcurrent when the receiving end is evacuated. The use of LCC compensation at the transmitter end of the WPT system can solve the problem that the receiving end is not allowed to be open or suddenly evacuated under SS compensation, but it still cannot eliminate all fault threats faced by the system under the resonant compensation parameters. Subsequently, detuning compensation parameters, LCC-N topology and dual-coupled LCC-S topology have also been proposed and used for fault-tolerant WPT topologies. Unfortunately, this type of method sacrifices the zero phase angle characteristics of conventional WPT systems and loses the load-independent CC or CV output characteristics when using common compensation topologies and resonant compensation parameters. Therefore, under the condition of meeting the staged CC-CV output required for lithium battery wireless charging, the fault tolerance problem under load open or short-circuit conditions is even more difficult. Summary of the invention

[0006] In view of the above-mentioned problems existing in the prior art, the object of the present invention is to provide a highly fault-tolerant constant current and constant voltage output self-switching wireless power transmission system to solve the technical problems in the prior art such as the difficulty in providing CC-CV output, the complex CC-CV output switching control, and the inability to achieve fault tolerance performance while ensuring zero phase angle.

[0007] In order to solve the above problems, the technical solution adopted by the present invention is as follows:

[0008] The highly fault-tolerant constant current and constant voltage output self-switching wireless power transmission system of the present invention comprises a high-frequency inverter, a first rectifier and a second rectifier;

[0009] The system also includes a first transmitting coil, a first compensation capacitor, a second transmitting coil, a second compensation capacitor, and a parallel compensation capacitor;

[0010] The high-frequency inverter is connected in series with the first transmitting coil and the first compensation capacitor, and the high-frequency inverter, the first transmitting coil and the first compensation capacitor connected in series are simultaneously connected in parallel with the parallel compensation capacitor;

[0011] The second transmitting coil is connected in series with the second compensation capacitor, and the second transmitting coil and the second compensation capacitor connected in series are simultaneously connected in parallel with the parallel compensation capacitor;

[0012] The input port of the first rectifier is connected in series with a first receiving compensation capacitor and a first receiving coil. The input port of the second rectifier is connected in series with a second receiving compensation capacitor and a second receiving coil. The output ports of the first rectifier and the second rectifier are both connected in parallel with a load resistor.

[0013] Further, in the magnetic coupler structure of this system, the first transmitting coil and the second transmitting coil form the transmitting end of the magnetic coupler. The first transmitting coil includes four square-shaped transmitting planar windings, and these four transmitting planar windings are connected in series, and any two adjacent transmitting planar windings are connected in series in the same direction. The four transmitting planar windings together form the first transmitting coil in a "field" shape, and the second transmitting coil is planar square.

[0014] In the magnetic coupler structure of this system, the first receiving coil and the second receiving coil form the receiving end of the magnetic coupler. The first receiving coil includes four square-shaped receiving planar windings, and these four receiving planar windings are connected in series, and any two adjacent receiving planar windings are connected in series in the same direction. The four receiving planar windings together form the first receiving coil in a "field" shape, and the second receiving coil is planar square.

[0015] In the magnetic coupler structure of this system, the transmitting end and the receiving end of the magnetic coupler are arranged parallel to each other up and down, and the transmitting end and the receiving end of the magnetic coupler are coaxial.

[0016] Further, the capacitance values of the first compensation capacitor / the first receiving compensation capacitor / the second compensation capacitor / the second receiving compensation capacitor / the parallel compensation capacitor are determined by the following formula:

[0017]

[0018] where, L p1 and L p2 are the self-inductances of the first transmitting coil and the second transmitting coil respectively, C p1 and C p2 are the capacitance values of the first compensation capacitor and the second compensation capacitor respectively, C0 is the capacitance value of the parallel compensation capacitor, L s1 and L s2 are the self-inductances of the first receiving coil and the second receiving coil respectively, C s1 and C s2 are the capacitance values of the first receiving compensation capacitor and the second receiving compensation capacitor respectively.

[0019] Further, the first transmitting coil is decoupled from the second transmitting coil and the second receiving coil respectively, and the second transmitting coil is decoupled from the first transmitting coil and the first receiving coil respectively.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The wireless power transmission system described in the present invention has a constant current and constant voltage self-switching characteristic, and its output characteristics can be passively switched between constant current output and constant voltage output under a certain critical load resistance value without any active control. The system also has the ability to tolerate load open circuit or short circuit faults, and can maintain the zero phase angle characteristics commonly possessed by conventional wireless power transmission systems. The system adopts resonant compensation, and the compensation parameter configuration is simple, reasonable and efficient. The first transmitting coil of the system also acts as a compensation element. The transmitting end has a high degree of integration, and the receiving end adopts a series compensation method. There are few compensation elements and no compensation inductance is required. It is suitable for consumer electronic products, wireless charging of electric vehicles and other applications that have high requirements on the volume, weight and power density of the receiving end. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the circuit connection structure of this system;

[0023] Figure 2 This is a schematic diagram of the structure of the system applied to the magnetic coupler;

[0024] Figure 3 Design parameters for trial-producing the magnetic coupler in the embodiment;

[0025] Figure 4 A schematic diagram showing the variation of output voltage and output current with load resistance in an embodiment;

[0026] Figure 5 Schematic diagram of test results under fault conditions in the embodiment. DETAILED DESCRIPTION

[0027] The present invention is further described below in conjunction with specific embodiments.

[0028] The highly fault-tolerant constant current and constant voltage output self-switching wireless power transmission system of the present invention has a circuit connection structure as follows: Figure 1 As shown, specifically, the system first includes a high frequency inverter U p and a first rectifier and a second rectifier.

[0029] The system also includes a first transmitting coil L p1 , the first compensation capacitor C p1 , the second transmitting coil L p2 , the second compensation capacitor C p2 And parallel compensation capacitor C0. High frequency inverter U p With the first transmitting coil L p1 and the first compensation capacitor C p1Phase series, phase series high frequency inverter U p , the first transmitting coil L p1 and the first compensation capacitor C p1 At the same time, it is connected in parallel with the parallel compensation capacitor.

[0030] The second transmitting coil L p2 With the second compensation capacitor C p2 The second transmitting coil L connected in series p2 and the second compensation capacitor C p2 At the same time, it is connected in parallel with the parallel compensation capacitor C0.

[0031] The input port of the first rectifier is connected in series with a first receiving compensation capacitor C s1 and the first receiving coil L s1 The input port of the second rectifier is connected in series with a second receiving compensation capacitor C s2 and the second receiving coil L s2 The output port of the first rectifier and the output port of the second rectifier are both connected to the load resistor R d Connect in parallel.

[0032] M ps1 is the first transmitting coil L p1 With the first receiving coil L s1 The mutual inductance between ps2 The second transmitting coil L p2 With the second receiving coil L s2 The mutual induction between.

[0033] Among them, the capacitance of the first compensation capacitor / first receiving compensation capacitor / second compensation capacitor / second receiving compensation capacitor / parallel compensation capacitor is determined by the following formula:

[0034]

[0035] The first transmitting coil L p1 Respectively with the second transmitting coil L p2 , the second receiving coil L s2 Decoupling, the second transmitting coil L p2 Then respectively with the first transmitting coil L p1 and the first receiving coil L s1 Decoupling.

[0036] like Figure 2 As shown, in the magnetic coupler structure using the above system, the first transmitting coil L p1 and the second transmitting coil L p2 The transmitting end of the magnetic coupler is constituted, specifically, the first transmitting coil L p1It includes four square-shaped transmitting planar windings, which are connected in series, and any two adjacent transmitting planar windings are connected in series in the same direction. The four transmitting planar windings together form a first transmitting coil L in the shape of a Chinese character "field". p1 , correspondingly, the second transmitting coil L p2 is square-shaped in plane.

[0037] The first receiving coil L s1 and the second receiving coil L s2 constitute the receiving end of the magnetic coupler. The first receiving coil L s1 includes four square-shaped receiving planar windings, which are connected in series, and any two adjacent receiving planar windings are connected in series in the same direction. The four receiving planar windings together form a first receiving coil L in the shape of a Chinese character "field". s1 , while the second receiving coil L s2 is also square-shaped in plane.

[0038] In this magnetic coupler structure, its transmitting end and receiving end are placed in parallel, and their four peripheral edges are parallel. When facing each other, their centers are located on the same vertical line.

[0039] In this embodiment, the design parameters of the adopted magnetic coupler are as Figure 3 shown. All the coils and windings of this magnetic coupler are closely wound.

[0040] According to Figure 3 the design parameters in, a magnetic coupler is trial-produced. The self-inductances of the first transmitting coil L p1 , the second transmitting coil L p2 , the first receiving coil L s1 and the second receiving coil L s2 of the magnetic coupler are measured to be 158.41 μH, 101.30 μH, 160.50 μH and 100.44 μH respectively. Correspondingly, at the rated working frequency of 85 kHz of the system, the capacitance values of each compensation capacitor are designed according to the above calculation formula as C p1 = 24.84 nF, C0 = 199.55 nF, C p2 = 41.89 nF, C s1 = 21.79 nF and C s2 = 34.84 nF.

[0041] Due to the constraints of the adopted magnetic coupler structure, the first transmitting coil L p1 and the second transmitting coil L p2 , the first transmitting coil L p1 and the second receiving coil L s2 , the second transmitting coil L p2 and the first transmitting coil L p1 , the second transmitting coil Lp2 With the first receiving coil L s1 The mutual inductance between them can be neglected.

[0042] In order to reflect the output voltage or output current of the wireless power transmission system when the load changes continuously, a simulation model is built using the above parameters to verify the constant current and constant voltage output self-switching characteristics of the wireless power transmission system. The results are as follows: Figure 4 As shown in the figure, the wireless power transmission system has a constant current output characteristic when the load resistance is small and a constant voltage output characteristic when the load resistance is large, and will spontaneously switch from constant current output to constant voltage output under a certain critical load resistance.

[0043] The test prototype was built to test the fault tolerance of the wireless power transmission system to load open circuit and short circuit faults. The results are as follows: Figure 5 As shown in the figure. o and η are the system output power and transmission efficiency respectively. It can be seen from the figure that the fault current of the system is suppressed within a certain range under the load open circuit and short circuit conditions, and no large overcurrent and overvoltage will occur.

Claims

1. A highly fault-tolerant constant current and constant voltage output self-switching wireless power transmission system, characterized in that: The system includes a high-frequency inverter, a first rectifier, and a second rectifier; The system further includes a first transmitting coil, a first compensation capacitor, a second transmitting coil, a second compensation capacitor, and a parallel compensation capacitor; The high-frequency inverter is connected in series with the first transmitting coil and the first compensation capacitor, and the series-connected high-frequency inverter, first transmitting coil, and first compensation capacitor are simultaneously connected in parallel with the parallel compensation capacitor; The second transmitting coil is connected in series with the second compensation capacitor, and the series-connected second transmitting coil and second compensation capacitor are simultaneously connected in parallel with the parallel compensation capacitor; A first receiving compensation capacitor and a first receiving coil are connected in series at the input port of the first rectifier, a second receiving compensation capacitor and a second receiving coil are connected in series at the input port of the second rectifier, and the output ports of the first rectifier and the second rectifier are both connected in parallel with a load resistor.

2. The highly fault-tolerant constant current and constant voltage output self-switching wireless power transmission system according to claim 1, characterized in that: In the magnetic coupler structure applying this system, the first transmitting coil and the second transmitting coil form the transmitting end of the magnetic coupler. The first transmitting coil includes four square-shaped transmitting planar windings, and these four transmitting planar windings are connected in series, and any two adjacent transmitting planar windings are connected in series in the same direction. The four transmitting planar windings together form the first transmitting coil in a "field" shape, and the second transmitting coil is planar square; In the magnetic coupler structure applying this system, the first receiving coil and the second receiving coil form the receiving end of the magnetic coupler. The first receiving coil includes four square-shaped receiving planar windings, and these four receiving planar windings are connected in series, and any two adjacent receiving planar windings are connected in series in the same direction. The four receiving planar windings together form the first receiving coil in a "field" shape, and the second receiving coil is planar square; In the magnetic coupler structure applying this system, the transmitting end and the receiving end of the magnetic coupler are arranged parallel to each other vertically, and the transmitting end and the receiving end of the magnetic coupler are coaxial.

3. The highly fault-tolerant constant current and constant voltage output self-switching wireless power transmission system according to claim 1, characterized in that: The capacitance values of the first compensation capacitor / first receiving compensation capacitor / second compensation capacitor / second receiving compensation capacitor / parallel compensation capacitor are determined by the following formula: Among them, L p1 and L p2 are the self-inductance of the first transmitting coil and the self-inductance of the second transmitting coil, C p1 and C p2 are the first compensation capacitor and the second compensation capacitor respectively, C0 is the parallel compensation capacitor, L s1 and L s2 are the self-inductance of the first receiving coil and the self-inductance of the second receiving coil, C s1 and C s2 are respectively the first receiving compensation capacitor capacitance and the second receiving compensation capacitor capacitance.

4. The highly fault-tolerant constant current and constant voltage output self-switching wireless power transmission system according to claim 1, characterized in that: The first transmitting coil is decoupled from the second transmitting coil and the second receiving coil respectively, and the second transmitting coil is decoupled from the first transmitting coil and the first receiving coil respectively.

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