Stacked dual load SCC-WPT system with constant output and load-independent characteristics

Abstract

The application relates to the technical field of single-capacitance coupling wireless power transmission (SCC-WPT), and particularly discloses a laminated double-load SCC-WPT system with constant output and load-independent characteristics. The coupling mechanism of the system adopts a laminated triode plate structure (a transmitting plate P1, a first laminated receiving plate and a second laminated receiving plate). The system has two receiving ends, and two loads are charged or powered by the two receiving ends respectively. One receiving end adopts an LCLC-S compensation structure to realize constant voltage (CV) output, and the other receiving end adopts an LCLC-M topological structure to realize constant current (CC) output. When one of the receiving ends is removed from the transmitting plate or is moved into the transmitting plate, the output characteristics of the other receiving end are not affected. Meanwhile, stable output power can be obtained at any position in the transmitting plate by the two receiving ends, and flexible power supply in a two-dimensional plane of a mobile device can be realized.

Description

Technical Field

[0001] This invention relates to the field of single capacitor coupled wireless power transfer (SCC-WPT) technology, and more particularly to a stacked dual-load SCC-WPT system with constant output and load independence characteristics. Background Technology

[0002] Electrically-coupled wireless power transfer (EC-WPT) is a wireless power transfer (WPT) technology that uses a metal plate as the coupling mechanism and a high-frequency electric field as the power carrier. Due to the advantages of its lightweight and low-cost coupling mechanism, as well as the low eddy current losses in the surrounding metal objects, EC-WPT technology has received widespread attention and research.

[0003] EC-WPT technology has been well studied in several research areas, including compensation networks, coupling structures, parameter design and optimization, and system and dynamic analysis. Most previous research has focused on traditional EC-WPT systems, which require two pairs of metal plates to form a circuit loop. However, the cross-coupling capacitance between each pair of metal plates can limit the flexibility of load power supply, especially in applications involving two-dimensional planar dynamic mobile devices.

[0004] In recent years, the demand for wireless power transfer systems in mobile devices has been increasing, including the ability to power multiple independent devices, different constant output characteristics, and spatial degrees of freedom. Previous research on Single Transmitter and Multiple Receiver (STMR) systems using traditional EC-WPT technology has primarily focused on efficiency optimization and topology compensation. However, due to the influence of cross capacitance, STMR systems under traditional EC-WPT technology can only operate under well-aligned conditions, or the load can only move freely in one dimension during charging. In contrast, Single Capacitor Coupled Wireless Power Transfer (SCC-WPT) technology overcomes this problem and offers greater flexibility, making it more suitable for STMR systems.

[0005] SCC-WPT technology forms a complete electrical loop by using the stray capacitance of the receiver components and the self-capacitance of the metal plate to ground the primary side. This technology offers many advantages, such as reducing the number of coupling mechanism plates, improving space utilization, and avoiding cross-coupling between coupling mechanism plates. Therefore, this technology helps improve the spatial freedom of the system to provide flexible power supply services to the load. Existing literature uses two metal balls with a virtual self-capacitance path to enhance the system's ground coupling capacitance, allowing the system's transmission distance to exceed the size of the coupling mechanism. The stray capacitance between the electric vehicle chassis and the ground can also be used as a current return path to achieve stable power transmission. Simultaneously, in certain special applications, the number of coupling plates can be reduced. For example, in power transmission line monitoring (PTLM) of railway electric vehicles, the primary and secondary sides of the system are connected or equivalently short-circuited. However, previous research on SCC-WPT technology has mainly focused on single transmits and single receiver (STSR) systems, while STMR systems employing SCC-WPT technology have not yet been studied. Summary of the Invention

[0006] This invention provides a stacked dual-load SCC-WPT system with constant output and independent load characteristics. The technical problem it solves is: how to realize a dual-load SCC-WPT system with constant output and independent load characteristics, while enabling one receiver to achieve constant voltage output and the other receiver to achieve constant current output.

[0007] To address the above technical problems, this invention provides a cascaded dual-load SCC-WPT system with constant output and independent load characteristics, comprising a transmitter and a receiver. The transmitter includes a DC power supply, a full-bridge inverter, an LCLC resonant network, and a transmitter plate P1 connected in sequence. The receiver includes a constant voltage output receiver and a constant current output receiver. The constant voltage output receiver includes a first cascaded receiver plate, an S-type compensation network, a first rectifier filter circuit, and a first load connected in sequence. The constant current output receiver includes a second cascaded receiver plate, an M-type compensation network, a second rectifier filter circuit, and a second load connected in sequence. The first cascaded receiver plate includes receiver plates P2 and P3, and the second cascaded receiver plate includes receiver plates P4 and P5. Receiver plates P2 and P4 are opposite to the transmitter plate P1.

[0008] Preferably, the LCLC resonant network includes an inductor L p1 Capacitor C p1 Inductor L p2 With capacitor Cex1 , where L p1 With C p1 Connected in series between the two output terminals of the full-bridge inverter, L p2 C ex1 Series in C p1 Between the two ends of L p2 C p2 The common terminal is connected to the transmitting electrode P1;

[0009] The parameter design of the LCLC resonant network satisfies:

[0010] ,

[0011] in, C is the system's operating angular frequency; total The equivalent capacitance of the coupling mechanism is expressed as:

[0012] ,

[0013] And there is,

[0014] ,

[0015] ,

[0016] ,

[0017] , Let C1 and C2 be the coupling coefficients of the two receiving end coupling mechanisms. a C b C M1a C M1b A1, B1, D1, E1, B2, E2, A3, and D3 are all equivalent capacitances, and C is the capacitance. ij Indicates plate P i With plate P j The capacitance formed, i,j=1,2,3,4,5, when i=j, C ij This represents the mutual capacitance between the two plates.

[0018] Preferably, the S-shaped compensation network uses a series inductor L a L a One end of L is connected to the receiving plate P2, and the other end is connected to one input terminal of the first rectifier and filter circuit. The other input terminal of the first rectifier and filter circuit is connected to the receiving plate P3; and L a The parameter design satisfies:

[0019] .

[0020] Preferably, the M-type compensation network includes a connection to the primary coil L. b1 Secondary coil L b2 and capacitor C rb Primary coil L b1 The two ends are connected to receiving plate P4 and receiving plate P5 respectively, and the secondary coil L b2 and capacitor C rb It is connected in series between the two input terminals of the first rectifier and filter circuit;

[0021] The parameter design of the M-type compensation network satisfies:

[0022] .

[0023] Preferably, the system parameters are designed using the following steps:

[0024] S1. Determine the system's input voltage, operating frequency f, and load value;

[0025] S2. Set and optimize the dimensions of the coupling mechanism composed of 5 electrode plates according to space constraints;

[0026] S3. Calculate parameters C1 and C based on the designed coupling mechanism and dimensions. a C b C M1a C M1b C total ;

[0027] S4. Based on parameters C1, C a C b C M1a C M1b C total Calculate parameter L p1 C p1 L p2 C ex1 L a L b1 L b2 C rb , and L b1 L b2 The coupling coefficient k between b ;

[0028] S5, according to parameter L p1 L p2 C a C M1b Calculate the output voltage gain G of the constant voltage output receiver. va According to parameter L p1 L p2 C M1b f, C b Lb1 L b2 k b Calculate the output current gain G of the constant current output receiver. ib ;

[0029] S6, Determine G va G ib Does it meet the requirements? If so, use the current parameters as the final parameters; otherwise, return to step S4 to adjust the boost ratio L. p2 / L p1 Or coupling coefficient k b Until G va G ib To meet the needs.

[0030] Preferably, in step S2, the emitting electrode P1 is a rectangular electrode, but any shape can be used depending on actual needs. The receiving electrodes P2, P3, P4, and P5 are all square electrodes, but other shapes can also be used. The dimensions of the receiving electrodes P2, P3, P4, and P5 are all smaller than that of the emitting electrode P1. The side lengths of electrodes P2, P3, P4, and P5 are l2, l3, l4, and l5, respectively. The distances between electrode P1 and electrodes P2 and P4 are d1 and d3, respectively; the distance between electrode P2 and electrode P3 is d2; and the distance between electrode P4 and electrode P5 is d4. The dimensional parameters of the five metal electrodes are designed using the following steps:

[0031] 1) Determine the dimensions of plate P1, as well as d2 and d3, based on actual application requirements;

[0032] 2) Determine the selectable range of l2, l3, l4, and l5 based on actual application requirements;

[0033] 3) In constant voltage mode, l2 is determined to be the maximum value in its selectable range, l3 is the larger value in its selectable range, and d2 is the maximum or larger value in its selectable range; in constant current mode, l4 is the maximum value in its selectable range, l5 is equal to l4, and d4 is the smaller or minimum value in its selectable range.

[0034] Preferably, in step S5, G va Calculate using the following formula:

[0035] .

[0036] Preferably, in step S5, G ib Calculate using the following formula:

[0037] .

[0038] This invention provides a stacked dual-load SCC-WPT system with constant output and load independence characteristics. The coupling mechanism of this system adopts a stacked three-plate structure (emitter plate P1, first stacked receiver plate, and second stacked receiver plate). The system has two receivers, one for charging / powering two loads. One receiver uses an LCLC-S compensation structure to achieve constant voltage (CV) output, and the other uses an LCLC-M topology to achieve constant current (CC) output. Removing or moving one receiver from or into the emitter plate does not affect the output characteristics of the other receiver. Furthermore, both receivers can obtain stable output power at any position within the emitter plate, enabling flexible power supply for two-dimensional planes in mobile devices. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of a wireless charging desktop based on a stacked SCC-WPT system provided in an embodiment of the present invention;

[0040] Figure 2 This is a structural diagram of the dual-load stacked SCC-WPT system provided in an embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of the full capacitance of the dual-load stacked SCC-WPT system provided in an embodiment of the present invention;

[0042] Figure 4 This is a three-port circuit model diagram of the dual-load coupling mechanism provided in the embodiment of the present invention;

[0043] Figure 5 This is provided by the embodiments of the present invention when U a =U b Equivalent circuit model diagram of the coupling mechanism when =0;

[0044] Figure 6 This is a controlled source equivalent model diagram of the coupling mechanism provided in the embodiments of the present invention;

[0045] Figure 7 This is a controlled source model diagram of the dual-load coupling mechanism provided in an embodiment of the present invention when cross-coupling between receiving boards is ignored;

[0046] Figure 8 Here are the output network diagrams under voltage source provided in the embodiments of the present invention: (a) constant voltage output network, (b) constant current output network;

[0047] Figure 9 This is a topology diagram of a stacked dual-load SCC-WPT system with constant output and independent load characteristics provided in an embodiment of the present invention.

[0048] Figure 10 This is the equivalent circuit diagram of the dual-load SCC-WPT system provided in the embodiments of the present invention;

[0049] Figure 11 Here are structural diagrams of the dual-load compact coupling mechanism provided in the embodiments of the present invention: (a) side view, (b) 3D view;

[0050] Figure 12 The coupling capacitor C provided in this embodiment of the invention is when d1=d2=5mm. M1a The relationship between the electrode side lengths l2 and l3 is shown in the diagram.

[0051] Figure 13 The capacitor C provided in this embodiment of the invention is when d1=d2=5mm. a and C M1a / C a Relationship with plate side lengths l2 and l3: (a) Capacitance C a (b)C M1a / C a ;

[0052] Figure 14 The embodiment of the present invention provides C when d1=5mm and l2=400mm. M1a C a and C M1a / C a The relationship between distance d2 and the distance d2 is shown in the graph.

[0053] Figure 15 This is a flowchart of system parameter design provided in an embodiment of the present invention;

[0054] Figure 16 This is provided by the embodiments of the present invention when R La =10Ω, R Lb The output voltage and current of the inverter and the output waveforms of the two loads when the resistance is 750Ω;

[0055] Figure 17 These are system waveform diagrams under different load resistances provided in the embodiments of the present invention;

[0056] Figure 18 Here are the output characteristic diagrams of the system provided in this embodiment of the invention: (a) Load A, (b) Load B;

[0057] Figure 19 This is a diagram showing the overall output power and efficiency of the system under different load resistances provided in the embodiments of the present invention;

[0058] Figure 20 These are experimental waveform diagrams provided in the embodiments of the present invention: (a) load only A, (b) load only B;

[0059] Figure 21 The following are waveform diagrams of load being moved in and out according to embodiments of the present invention: (a) when load A is moved out, (b) when load A is moved in. Detailed Implementation

[0060] 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.

[0061] Figure 1 A wireless charging desktop with an SCC-WPT system stacked coupling mechanism is displayed. From Figure 1 As can be seen, the SCC-WPT system only requires a single metal plate for the transmitter, allowing mobile devices (laptops, tablets, etc.) to move freely on the transmitter. However, since the receiver of a mobile device typically requires integration, its stray capacitance is very small, which degrades the transmission performance of the SCC-WPT system. Therefore, this example proposes a three-plate stacked coupling mechanism to increase the coupling capacitance and improve system performance.

[0062] Figure 2 The proposed stacked dual-load SCC-WPT structure is shown in the diagram. The transmitter plate of the receiver only requires one metal plate P1. P2 and P3 serve as the receiver plates for receiver A. P4 and P5 constitute the receiver plates for receiver B. The stacked structure of the receiver plates reduces the space occupied by the receiver, which is beneficial for equipment miniaturization. When the distance between the metal plate and the ground is much larger than the size of the metal plate, the capacitance C between each coupling plate and the ground... plate Approaching its own capacitance C plate_self Half of it.

[0063] (1)

[0064] Where p and s represent the perimeter and area of ​​the plate, respectively. This represents the dielectric constant. Furthermore, a capacitance can be formed between any two plates. Therefore, the dual-load coupling mechanism has a total of 15 equivalent capacitances, including mutual capacitance, cross-coupling capacitance, and self-capacitance, such as... Figure 3 As shown, C ij Indicates plate P i With plate P j The capacitance formed, i,j=1,2,3,4,5, when i=j, C ij This represents the mutual capacitance between the two plates.

[0065] according to Figure 3A three-port circuit model of a dual-load coupling mechanism can be established, such as... Figure 4 As shown, where U1 is the primary voltage of the coupling mechanism, U a and U b These are the output voltages of the two receiving terminals, respectively. This model can be viewed as a three-port network. Therefore, the 3×3 matrix relating the port voltages and port currents can be represented by equation (2), where Y... ij The Y parameter of the three-port network is shown in equation (3).

[0066] (2)

[0067] in,

[0068] (3)

[0069] Once the Y parameters are determined, the relationship between the port voltage and the port current can be obtained. According to equation (3), when the port voltage U a and U b When Y approaches zero, 11 Y 21 and Y 31 It can be obtained through the ratio between different currents and voltages. Voltage U a and U b A value of zero indicates that the port is short-circuited. Therefore, the three-port circuit model can be simplified to a sixth-order equivalent circuit, such as... Figure 5 As shown.

[0070] Using node analysis, in Figure 5 The ground side is defined as the reference node. The relationship between the input current and the node voltage can be expressed as:

[0071] (4)

[0072] in,

[0073] (5)

[0074] According to formulas (4) and (5), the node voltage u p2 and u p4 This is represented by formula (6).

[0075] (6)

[0076] In addition, according to Figure 5 Current I a and I b It can be represented as follows:

[0077] (7)

[0078] According to equations (3), (5), (6), and (7), Y 11 Y 21 and Y 31 The parameters can be obtained as shown in equation (8).

[0079] (8)

[0080] in,

[0081] (9)

[0082] Therefore, other Y parameters can be calculated using the same method. When voltage U1 and U... b When set to zero, parameter Y can be obtained. 12 Y 22 and Y 32 At the same time, when U1 and U a When it is zero, the parameter Y can be obtained. 13 Y 23 and Y 33 The expressions are given in Table 1, which summarizes these parameters and equations.

[0083] Table 1. Y-parameters of the coupling mechanism

[0084]

[0085] It is important to emphasize that, according to the reciprocity theory, some of these parameters are equal, as shown below:

[0086] (10)

[0087] In passive port networks, the open-circuit impedance matrix Z and the short-circuit admittance matrix Y are inverses of each other, as shown in the following equation:

[0088] (11)

[0089] The coupling coefficient of the coupling mechanism is defined as:

[0090] (12)

[0091] Based on the above analysis and formulas (11) and (12), the Z-parameters and mutual capacitance coefficients of the three-port network can be obtained as shown in the following formulas:

[0092] (13)

[0093] For ease of analysis, the matrix G parameters of the three-port network are calculated in this example. The relationship between port current and port voltage is expressed as Equation (14).

[0094] (14)

[0095] Based on the open-circuit impedance matrix Z and the short-circuit admittance matrix Y, matrix G can be equivalently represented as:

[0096] (15)

[0097] Therefore, the G parameter can be obtained as shown in equation (16):

[0098] (16)

[0099] in .

[0100] Based on the above analysis, the equivalent circuit of the coupling mechanism can be derived as follows: Figure 6 As shown. The coupling mechanism can be equivalent to a three-controlled-source model, where any controlled source depends on the outputs of the other two ports. The primary and secondary sides are coupled to each other, and the port voltages and port currents of the three ports are U1, I1, and U2, respectively. a I a U b and I b .

[0101] In practical applications, mobile devices often need to be frequently moved in and out of the receiving plate. Therefore, mobile devices must have independent characteristics, meaning that when the load resistance of one device changes or the mobile device is moved in or out, the other device can obtain a stable output so that its charging process is not affected. Figure 6 As can be seen, when there is mutual coupling between the receiving plates, the output characteristics of any receiving end are determined by the transmitting end and other receiving ends. In reality, the charging air gaps of mobile devices are relatively small, such as mobile phones, laptops, and some desktop application devices. In this case, the mutual capacitance of the coupling mechanism will be much larger than the cross capacitance between the two receiving devices. Therefore, when the transmission distance is short, the cross capacitance, i.e., capacitance C, can be ignored. 24 C 25 C 34 C 35 and C Mab It can be considered zero. Therefore, the parameters of the coupling mechanism can be simplified to:

[0102] (17)

[0103] At this point, the two receivers are independent of each other, and the output characteristics of each receiver are determined solely by the primary-side output voltage U1. When any receiver is moved in or out, as long as voltage U1 remains constant, the output characteristics of the other receivers can remain unchanged. Therefore, the equivalent circuit of the coupling mechanism can be simplified, such as... Figure 7 As shown. In Figure 7 In the middle, C total and I total The parameters are defined as follows:

[0104] (18)

[0105] In practical applications, some devices typically require constant voltage or constant current power supply. When using a voltage-source inverter, a fourth-order compensation network is needed to achieve CV output without affecting the zero-phase angle (ZPA). Meanwhile, a series mutual inductor circuit can achieve CC output, with the output current depending on the mutual inductance M. 12 ,like Figure 8 As shown in (a) and (b).

[0106] like Figure 9 As shown, this embodiment of the invention provides a stacked dual-load SCC-WPT system with constant output and independent load, including a transmitter and a receiver. The transmitter includes a DC power supply (E) connected in sequence. dc The system consists of a full-bridge inverter (composed of four power MOSFETs S1-S4), an LCLC resonant network, and an emitter plate P1. The LCLC resonant network includes an inductor L... p1 Capacitor C p1 Inductor L p2 With capacitor C ex1 , where L p1 With C p1 Connected in series between the two output terminals of the full-bridge inverter, L p2 C ex1 Series in C p1 Between the two ends of L p2 C p2 The common terminal is connected to the emitter plate P1. The system is connected to ground via the primary side.

[0107] The receiving end includes a constant voltage output receiver and a constant current output receiver.

[0108] The constant voltage output receiver includes a first stacked receiving electrode (stacked receiving electrode A), an S-type compensation network, and a first rectifier filter circuit (composed of diode D) connected in sequence. 1a D 2a D 3a D 4a Composition) and first load (R) La The S-type compensation network uses a series inductor L.a L a One end is connected to the receiving plate P2, and the other end is connected to one input terminal of the first rectifier and filter circuit. The other input terminal of the first rectifier and filter circuit is connected to the receiving plate P3.

[0109] The constant current output receiver includes a second stacked receiving plate (stacked receiving plate B) connected in sequence, an M-type compensation network, and a second rectifier filter circuit (composed of diode D). 1b D 2b D 3b D 4b Composition) and second load (R) Lb The first stacked receiving electrode includes receiving electrode P2 and receiving electrode P3, and the second stacked receiving electrode includes receiving electrode P4 and receiving electrode P5. Receiving electrode P2 and receiving electrode P4 are opposite to transmitting electrode P1. The M-type compensation network includes a primary coil L. b1 Secondary coil L b2 and capacitor C rb Primary coil L b1 The two ends are connected to receiving plate P4 and receiving plate P5 respectively, and the secondary coil L b2 and capacitor C rb It is connected in series between the two input terminals of the first rectifier and filter circuit. Primary coil L b1 Secondary coil L b2 Mutual inductance between them is represented by M b express.

[0110] according to Figure 8 The analysis shows that the LCLC compensation network can achieve CV output. In the compensation network at the receiving end, an S-type compensation network is used to implement CV mode and an M-type compensation network is used to implement CC output. The dual-load coupling mechanism consists of a transmitter board P1 and receiver boards P2, P3, P4, and P5. Figure 9 The equivalent circuit is as follows Figure 10 As shown. R eq This is the equivalent AC resistance of the rectifier and load resistor, and its equivalent AC resistance is R. eqa =8R La / π 2 R eqb =8R Lb / π 2 In addition, U b12 and U b21 The voltage is defined as follows:

[0111] (19)

[0112] Based on the above analysis, when the load needs to operate in CV mode, the system parameters need to satisfy the following equation:

[0113] (20)

[0114] According to equation (20), the expression for voltage U1 is shown below. It can be seen that when the inductance parameter is determined, voltage U1 is determined by the input voltage U. in Decide.

[0115] (twenty one)

[0116] According to equations (20) and (21), the output voltage of load A can be obtained as shown in the following equation:

[0117] (twenty two)

[0118] As can be seen from equation (22), the output voltage of load A is independent of the load resistance and is determined only by the inductance parameters, coupling mechanism parameters, and input voltage. Therefore, according to equation (22), the gain of the system output voltage can be obtained as follows:

[0119] (twenty three)

[0120] According to equation (23), the system can operate in CV mode, combined with equation R eqa =8R La / π 2 The output power of load A can be expressed as follows:

[0121] (twenty four)

[0122] Similarly, when the system needs to achieve CC output characteristics, the system's transmitter compensation structure also satisfies formula (20), and the system's receiver compensation network adopts an M-type compensation topology, the parameters of which must satisfy the following equations:

[0123] (25)

[0124] Then, according to Kirchhoff's laws, the voltage relationship and coupling relationship at the receiving end are listed below:

[0125] (26)

[0126] Where k b L represents b1 and L b2 The coupling coefficient between them.

[0127] Therefore, the receiving current of load B can be obtained by equation (26), as shown below:

[0128] (27)

[0129] According to formula (27), the output current of load B is independent of the load resistance, and a constant current output can be achieved. The gain of its output current is:

[0130] (28)

[0131] Solving equations (27) and R simultaneously eqb =8R Lb / π 2 The output power of load B is:

[0132] (29)

[0133] The system's output power depends on the number of loads, and the output power equals the sum of the output power of each load. Therefore, the output power of a dual-load system can be obtained by adding the two. It is important to emphasize that when parasitic resistance in the components is ignored, the input power equals the output power.

[0134] (30)

[0135] At the same time, the current at the system receiver can also be obtained, as shown in the following formula:

[0136] (31)

[0137] According to formulas (24) and (29), the system can operate in CV mode when the input voltage U in After the parameters of the inductor are determined, the output power P outa Depends on C in the coupling mechanism M1a and C a The ratio between them. Also, when the system operates in CC mode, the output power P... outb With capacitor C M1b Therefore, in order to obtain higher system power under the same parameters, it is necessary to design the coupling mechanism.

[0138] Figure 11 A schematic diagram of a dual-load compact coupling mechanism is given. For ease of analysis, a 1000mm×500mm aluminum plate is selected as the transmitting electrode P1, and a square aluminum plate is used as the receiving electrode. Table 2 lists the different dimensional parameters of the coupling mechanism. The coupling mechanism is simulated using the finite element simulation software Ansoft Maxwell, where the thickness of each aluminum plate is set to 1mm. Therefore, the mutual capacitance between each plate can be simulated. The capacitance to ground of each electrode in the coupling mechanism can be obtained by formula (1). Therefore, according to formulas (1) and (17), the coupling capacitance C can be calculated. M1a and C M1bMeanwhile, capacitors C1 and C a and C b This can also be obtained. Since the coupling mechanisms of receiver A and receiver B exhibit the same characteristics and results in the simulation, only the simulation results of the coupling structure of receiver A will be used for demonstration here.

[0139] Table 2 Dimensional parameters of the coupling mechanism

[0140]

[0141] Meanwhile, this example provides the capacitance C through simulation. a and ratio C M1a / C a The result, such as Figure 13 As shown in (a) and (b). From Figure 13 As can be seen from (a), the capacitance C a It increases with the increase of l2 and l3. When the electrode side lengths l2 and l3 are selected as 400mm, C a Approximately 318 pF. From Figure 13 As can be seen from (b), C M1a / C a The ratio increases with increasing l2, while increasing l3 will lead to C M1a / C a The ratio decreases. When l2 is 400mm and l3 is 300mm, the ratio is approximately 0.03. According to formula (20), in CV mode, the output power of the system depends on the ratio C. M1a / C a The higher the ratio, the higher the output power P. outa It can be as large as possible. Therefore, when the system is operating in CV mode, l2 should be as large as possible, and l3 should be minimized. However, it should be noted that C... a It also decreases as l3 decreases, which will lead to the resonant inductor L b The increase.

[0142] Finite element analysis was also performed on the distance d2. Figure 14 The distance d2 and coupling capacitance C are shown. M1a Capacitor C a and ratio C M1a / C a The relationship between them. As can be seen from the figure, when the distance d2 changes, the coupling capacitance C... M1a It remains almost unchanged. Furthermore, the capacitance C... a It decreases as distance d2 increases. Conversely, the ratio C... M1a / C a It increases with the increase of distance d2, and the smaller l3 is, the faster the ratio increases.

[0143] Based on the above analysis, when the system needs to operate in CV mode, the side length l2 should be chosen to be as large as possible, while l3 should be decreased simultaneously. However, because a side length l3 that is too small will cause C... a The resonant inductor L decreases, thus causing the resonant inductor L to... a The volume and dimensions are increasing, therefore the side length l3 should be appropriately reduced. At the same time, in order to further increase the ratio C... M1a / C a The distance d2 can be increased appropriately.

[0144] Similarly, when the system needs to operate in CC mode, according to equation (29), its output power depends not only on the ratio C M1b / C b It can also be achieved through mutual inductance M 12 To adjust. But C b The size is related to the inductance L b1 The volume and size, C b The larger the inductance L b1 The smaller the value, the better. Therefore, in CC mode, the capacitor C should be increased as much as possible. b The value of . To increase the capacitance C. b The side lengths l4 and l5 need to be consistent and as large as possible. At the same time, reducing the distance d4 can also yield a larger C. b And further reduce the inductor L b1 Its volume and size.

[0145] Overall, the dimensions of the five metal plates were designed using the following steps:

[0146] 1) Determine the dimensions of plate P1, as well as d2 and d3, based on actual application requirements;

[0147] 2) Determine the selectable range of l2, l3, l4, and l5 based on actual application requirements;

[0148] 3) In constant voltage mode, l2 is determined to be the maximum value within its selectable range, l3 to be the larger value within its selectable range, and d2 to be either the maximum or a larger value within its selectable range. In constant current mode, l4 is determined to be the maximum value within its selectable range, l5 is equal to l4, and d4 to be either the smaller or minimum value within its selectable range. Here, a larger value refers to a value greater than the median and less than the maximum value, and a smaller value refers to a value greater than the minimum value and less than the median value.

[0149] Based on the experimental conditions and space limitations of the laboratory, the dimensions of receiving plate P1 are set to 1000×500×1mm. According to the above analysis, the dimensions of plates P2 and P4 are set to 400mm×400mm×1mm, and the dimensions of plates P3 and P5 are selected as 300mm×300mm×1mm and 400mm×400mm×1mm, respectively. The transmission distances d1 and d3 are set to 5mm, distance d2 to 5mm, and distance d4 to 3mm. All capacitance parameters are listed in Table 3.

[0150] Table 3 Capacitance parameters of the coupling mechanism

[0151]

[0152] Based on the above results, the parameter design method for the system can be obtained. Figure 15 A flowchart illustrating the system design is provided, showing the relationships between all resonant network elements. Specifically, the system parameters are designed using the following steps:

[0153] S1. Determine the system input voltage (E) dc ), operating frequency f and load value (R) La R Lb );

[0154] S2. Set and optimize the dimensions of the coupling mechanism composed of 5 electrode plates according to space constraints;

[0155] S3. Calculate parameters C1 and C based on the designed coupling mechanism and dimensions. a C b C M1a C M1b C total ;

[0156] S4. Based on parameters C1, C a C b C M1a C M1b C total Calculate parameter L p1 C p1 L p2 C ex1 L a L b1 L b2 C rb , and L b1 L b2 The coupling coefficient k between b ;

[0157] S5, according to parameter L p1 L p2 C a CM1b Calculate the output voltage gain G of the constant voltage output receiver. va According to parameter L p1 L p2 C M1b f, C b L b1 L b2 k b Calculate the output current gain G of the constant current output receiver. ib ;

[0158] S6, Determine G va G ib Does it meet the application requirements? If so, use the current parameters as the final parameters; otherwise, return to step S4 to adjust the boost ratio L. p2 / L p1 Or coupling coefficient k b Until G va G ib To meet the needs of practical applications.

[0159] Typically, the operating frequency f is set empirically, and the transmission distance is usually set according to the limitations of the application field. The input voltage E... dc and resistive load R La R Lb It is determined by the application requirements of the equipment.

[0160] The coupling mechanism can be determined based on the above design. Once the dimensions of the coupling mechanism are determined, the capacitances C1 and C2 can be calculated using equations (1) and (17). a C b and coupling capacitor C M1a C M1b Parameter C total Then, equation (18) can be used for calculation, and the transmitter compensation should satisfy equation (20). When the system operates in CV mode, the receiver compensation structure only requires one inductor L. a Parameter L a Equation (20) can be used for calculation. Similarly, when the system operates in CC mode, the M-type topology is selected as the receiver compensation network, and parameter L can be obtained using equation (25). b1 L b2 and C rb .

[0161] according to Figure 9 The circuit design in the paper presents the experimental setup for the system, with a resonant frequency of 1.97MHz and an input voltage E. dc Set to 120V. According to... Figure 15The parameter design method is described, and the system parameters are listed in Table 4. The parameters in the experiment were measured using an LCR instrument (GWINSTEK LCR-8230).

[0162] Table 4 System Parameters

[0163]

[0164] Based on the theoretical analysis and simulation studies above, this example establishes a compact SCC-WPT experimental prototype with dual receivers. The coupling mechanism uses aluminum plates, and the dimensions of each plate are shown in Table 2. The measured capacitance parameters are consistent with the simulation parameters, as shown in Table 3. Table 4 provides detailed experimental prototype parameters. It should be noted that the capacitance C... 12 C 23 C 14 and C 45 The value is slightly larger than the simulated value. This is because square acrylic blocks were used in the experiment to separate the plates. The capacitance C was measured using an LCR meter. 12 C 23 C 14 and C 45 The actual measured values ​​were 330 pF, 231 pF, 312 pF and 520 pF, respectively.

[0165] The distance between the transmitter and receiver boards is 5mm, and the coupling capacitor C M1a Approximately 5.92 pF, C M1b Approximately 7.27 pF. Measurements were performed using a current probe (CYBERTEK CP8150A) and a differential voltage probe (DP6150). 1.97 MHz AC power modulation was achieved using a wide-bandgap silicon carbide (SiC) MOSFET IMZ120R045M1 and a SiC diode GHXS030A120S. Inductor L... p1 L p2 L ra L rb1 and L rb2 It is made of Litz wire with a diameter of 0.04×600. The resonant capacitor is obtained by connecting high-frequency C0G chip capacitor and film capacitor in series and parallel.

[0166] Experiments were conducted using resistors with different resistance values. Figure 16 Given when R La =10Ω and R Lb At a resistance of 750Ω, the inverter output voltage and current, and the output waveforms at both receiver terminals are shown. Current and voltage probes can affect the SCC-WPT system to some extent, but current probe testing is performed at load resistance R... LaWhen the circuit is in its branch, the system is almost unaffected. A pointer-type ammeter was also used in the experiment to verify the accuracy of the current probe. Furthermore, the receiver B uses an M topology, with resistor R... Lb Isolated from the coupling mechanism, the voltage probe has no impact on the system. A differential voltage probe is used to test receiver B because the output current gain at receiver B is too small; using a voltage probe to measure it will yield more accurate results.

[0167] Depend on Figure 16 The experimental waveforms show that the output power of receiver A is 46.2W, and the output power of receiver B is 45.6W. At this time, the input voltage E... dc and input current I dc The voltages were 120V and 1.36A respectively, and the overall DC-DC efficiency of the experimental prototype was 56.2%. According to... Figure 16 The experimental results show that the voltage gain at receiver A and the current gain at receiver B are approximately 0.18 and 0.0021, respectively. Based on the system parameters in Table 2, and combining formulas (23) and (28), the voltage gain G... va and current gain G ib The theoretical calculated values ​​are approximately 0.24 and 0.0031, respectively. The reason for the certain error between theory and experiment is that parasitic resistance and inverter and rectifier losses were ignored in the theoretical calculation.

[0168] Figure 17 Experimental results for different load resistances are presented. Based on... Figure 17 The output voltage of receiver A and the output current of receiver B are as follows: Figure 18 As shown in the figure. Experimental results show that receiver A can achieve an approximately constant voltage, and the rate of change gradually decreases as the load resistance increases. When the system is under light load conditions, receiver B can also operate approximately in constant current mode.

[0169] Based on experimental results under different load resistances Figure 19 The DC-DC efficiency and output power of the two receivers under different load resistances are presented. The total output power is 106.9W, 86.6W, and 95.9W, respectively, and the overall system efficiency exceeds 50% under different load conditions. Due to the high system frequency, most of the power loss comes from the parasitic resistance of the inverter, rectifier, and inductor. In addition, some losses will be generated in the grounding impedance of the self-capacitance. Furthermore, the constant-mode efficiency is closely related to the system efficiency, and future work will further improve efficiency by using high-quality factor electronics.

[0170] The system proposed in this example can not only achieve different constant characteristics, but also achieve mutual independence between the two receivers, that is, when one receiver is moved in or out, the other receiver will not be affected. Figure 20 Experimental results are presented when only load A or load B is placed on the transmitter plate. As the number of loads decreases, the input current I... in The output current I decreased to varying degrees. Meanwhile, compared to the case with two loads, the output current I... outa and output voltage U outb Almost unchanged, such as Figure 20 As shown. It's important to note that a slight change in current phase occurs due to the output power and capacitor C when a load is removed. total It will decrease slightly. However, the system's output characteristics will not be significantly affected because, compared to C... total In comparison, the reduction in capacitance is negligible.

[0171] For safety reasons, the DC voltage was uniformly set to 25V during the load independence experiment. Figure 21 (a) shows the dynamic waveform when load A is removed. Figure 21 (b) shows the dynamic waveform when load A is moved in. The output voltage of receiver B remains constant as the load is moved in or out, and loads A and B are independent of each other. Since the physical movement of the load in the experiment is manual, I... in The overcurrent is caused by changes in coupling during the movement of the receiving end. Therefore, due to the uncertainty of manual operation, the experimental results will vary slightly for each operation.

[0172] This invention provides a stacked dual-load SCC-WPT system with constant output and load independence characteristics. The coupling mechanism of this system employs a stacked three-plate structure (emitter plate P1, first stacked receiver plate, and second stacked receiver plate). The system has two receivers, one for charging / powering two loads. One receiver uses an LCLC-S compensation structure to achieve constant voltage (CV) output, and the other uses an LCLC-M topology to achieve constant current (CC) output. Removing or moving one receiver from or into the emitter plate does not affect the output characteristics of the other receiver. The emitter plate P1 is simply an aluminum plate, and the receivers have the same coupling capacitance at any position above P1. Therefore, the receivers can obtain stable output power within the P1 range. When the input voltage is set to 40V, bulbs A and B can maintain the same brightness when the receivers are placed in different positions within plate P1, thus enabling flexible power supply in a two-dimensional plane.

[0173] This embodiment proposes a compact three-plate coupling mechanism, which increases the coupling capacitance and improves system performance. It analyzes and simplifies the full-capacitance model of the dual-receiver coupling mechanism and establishes an equivalent controlled source model for the coupling mechanism. Based on the requirement of mobile devices for constant output, two topologies, LCLC-S and LCLC-M, are proposed to achieve CV and CC outputs, respectively. The resonance condition of the system is analyzed, and the output gain of the system is derived. The coupling mechanism is designed through simulation to obtain a high output gain for the system. Finally, a prototype of the dual-receiver SCC-WPT system is built based on the proposed topology and method, and the correctness of the theoretical analysis is verified through experiments.

[0174] The advantages of the cascaded dual-load SCC-WPT system, which features constant output and independent load characteristics, are as follows:

[0175] 1) In the proposed dual-receiver SCC-WPT system, the output of one receiver has constant voltage characteristics, while the output of the other receiver has constant current characteristics;

[0176] 2) The two receivers are independent of each other. When one receiver is moved in or out, the output characteristics of the other receiver can remain unchanged.

[0177] 3) The receiving electrode adopts a stacked structure, which can reduce the space occupied and is conducive to the miniaturization of the equipment.

[0178] 4) The system has the characteristic of free position charging / power supply within the range of the transmitting plate, and can obtain constant power output even when the receiving end is moving.

[0179] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A stacked dual load SCC-WPT system with constant output and load independent characteristics, characterized in that, The system comprises a transmitting end and a receiving end; the transmitting end comprises a direct current power supply, a full-bridge inverter, an LCLC resonant network and a transmitting plate P1 connected in sequence; the receiving end comprises a constant voltage output receiving end and a constant current output receiving end; the constant voltage output receiving end comprises a first laminated receiving plate, an S-shaped compensation network, a first rectification filter circuit and a first load connected in sequence, and the constant current output receiving end comprises a second laminated receiving plate, an M-shaped compensation network, a second rectification filter circuit and a second load connected in sequence; the first laminated receiving plate comprises a receiving plate P2 and a receiving plate P3, and the second laminated receiving plate comprises a receiving plate P4 and a receiving plate P5; the receiving plate P2, the receiving plate P4 and the transmitting plate P1 are opposite to each other. The LCLC resonance network comprises an inductance L p1 , a capacitance C p1 , an inductance L p2 and a capacitance C ex1 , wherein L p1 and C p1 are connected in series between two output terminals of the full-bridge inverter, L p2 , C ex1 are connected in series between two terminals of C p1 , and the common terminal of L p2 , C p2 is connected to the emitter plate P1; The parameters of the LCLC resonant network satisfy the following conditions: ， wherein is the operating angular frequency of the system; C total is an equivalent capacitance of the coupling mechanism, expressed as: ， The parameters of the M-shaped compensation network satisfy the following conditions: ， ， ， , Let C1 and C2 be the coupling coefficients of the two receiving end coupling mechanisms. a C b C M1a C M1b A1, B1, D1, E1, B2, E2, A3, and D3 are all equivalent capacitances, and C is the capacitance. ij Indicates plate P i With plate P j The capacitance formed, i,j=1,2,3,4,5, when i=j, C ij This represents the mutual capacitance between the two plates.

2. The cascaded dual load SCC-WPT system with constant output and load independent characteristics according to claim 1, characterized in that: The S-type compensation network uses a series inductor L a L a One end of L is connected to the receiving plate P2, and the other end is connected to one input terminal of the first rectifier and filter circuit. The other input terminal of the first rectifier and filter circuit is connected to the receiving plate P3; and L a The parameter design satisfies: 。 3. The cascaded dual load SCC-WPT system with constant output and load independent characteristics according to claim 1, characterized in that: The M-type compensation network comprises a primary coil L b1 , a secondary coil L b2 and a capacitor C rb , two ends of the primary coil L b1 are connected with a receiving plate P4 and a receiving plate P5 respectively, and the secondary coil L b2 and the capacitor C rb are connected in series between two input ends of the first rectification filter circuit; The parameters of the system are designed by the following steps: 。 4. The cascaded dual load SCC-WPT system with constant output and load independent characteristics according to claim 3, wherein, S1, determining the input voltage, the working frequency f and the load value of the system; S2, setting and optimizing the size of the coupling mechanism composed of the five plates according to the space limitation; In the step S2, the transmitting plate P1 is a rectangular plate, the receiving plates P2, P3, P4 and P5 are square plates, the sizes of the receiving plates P2, P3, P4 and P5 are smaller than that of the transmitting plate P1; the side lengths of the plates P2, P3, P4 and P5 are l2, l3, l4 and l5 respectively, the distances between the plate P1 and the plates P2 and P4 are d1 and d3 respectively, the distance between the plates P2 and P3 is d2, and the distance between the plates P4 and P5 is d4; the size parameters of the five metal plates are designed by the following steps: S3. According to the designed coupling mechanism and size calculation parameters C1, C a b M1a M1b total ;​​​​ S4. Based on parameters C1, C a C b C M1a C M1b C total Calculate parameter L p1 C p1 L p2 C ex1 L a L b1 L b2 C rb , and L b1 L b2 The coupling coefficient k between b ; S5, according to the parameter L p1 , L p2 , C a , C M1b Calculate the output voltage gain G of the constant voltage output receiving end va , according to the parameter L p1 , L p2 , C M1b , f, C b , L b1 , L b2 , k b Calculate the output current gain G of the constant current output receiving end ib ; S6, judge G va , G ib Whether the application requirement is met, if yes, the current parameter is the final parameter, if not, return to step S4 to adjust the boost ratio L p2 / L p1 Or coupling coefficient k b Until G va , G ib The actual application requirement is met.

5. The cascaded dual load SCC-WPT system with constant output and load independent characteristics according to claim 4, wherein, 1) determining the size of the plate P1 and d2 and d3 according to the actual application requirement; 2) determining the optional ranges of l2, l3, l4 and l5 according to the actual application requirement; 3) in the constant voltage mode, determining l2 as the maximum value in its optional range, l3 as the larger value in its optional range, and d2 as the maximum value or the larger value in its optional range; in the constant current mode, determining l4 as the maximum value in its optional range, l5 equal to l4, and d4 as the smaller value or the minimum value in its optional range. ​ 6. The cascaded dual load SCC-WPT system with constant output and load independent characteristics according to claim 5, wherein, In said step S5, G va The following formula is used for the calculation: 。 7. The cascaded dual load SCC-WPT system with constant output and load independent characteristics according to claim 5, wherein, In said step S5, G ib The following formula is used for the calculation: 。

Images