Dual-load wireless power transmission system

Abstract

The invention discloses a dual-load wireless power transmission system, and relates to the field of wireless power transmission. The constant current receiver comprises a primary side circuit, a first receiver circuit and a second receiver circuit, the primary side circuit and the first receiver circuit are combined to form a CLS-S structure and output constant voltage, and the primary side circuit and the second receiver circuit are combined to form a CLC-CLC structure and output constant current. According to the invention, two paths of stable constant voltage and constant current output can be realized without a charge state detection and control circuit, the control is convenient, the structure is compact, the stability is high, and the circuit is suitable for various power supply fields requiring multiple outputs.

Description

Technical Field

[0001] The invention belongs to the field of wireless power transmission, and in particular relates to a dual-load wireless power transmission system. Background Art

[0002] Automated guided vehicles have broad application prospects in the future manufacturing and intelligent transportation fields due to their intelligence and convenience. However, with the high integration of power electronic equipment, automated guided vehicles contain a large number of devices. Due to the increase in charging targets, this limits their safety and convenience in industrial applications. In order to improve the safety and convenience of automated guided vehicles in applications, the wireless power transmission technology of automated guided vehicles has begun to attract widespread attention.

[0003] Wireless power transmission technology for automated guided vehicles is a newly developed field. It does not require frequent plugging and unplugging of connecting cables to complete energy transmission. Wireless charging technology for automated guided vehicles is usually based on the principle of electromagnetic induction or radio frequency energy transmission. By embedding a transmitter in the ground and installing a receiver on the chassis of the automated guided vehicle, power is transmitted to the charging device. The receiving device of the device that supports wireless charging uses the received power to power the on-board device.

[0004] The wireless charging system of the automatic guided vehicle contains a large number of devices, and each has its own charging requirements. For example, the constant current power supply of the widely used multi-string LEDs, the battery module is also preferably a constant current module, so it also requires dual-channel output. In order to enable the system to achieve stable constant voltage and constant current output under the condition of adding a large number of devices, the wireless charging system of the automatic guided vehicle currently mainly adopts the following methods:

[0005] DC-DC auxiliary technology: This method requires the addition of an additional DC-DC converter, which will occupy considerable space in the vehicle, increase weight and losses.

[0006] Phase-shift modulation technology: This method is difficult to achieve zero voltage switching under a larger load range, which will cause greater losses in the inverter.

[0007] Frequency conversion control technology: This method will cause frequency bifurcation and make the system unable to work under zero phase angle conditions, which will lead to poor system stability and increased losses.

[0008] In summary, the wireless charging technology of automated guided vehicles is a technology with broad application prospects, which helps to change the power supply mode of automated guided vehicles and achieve higher efficiency, higher positioning accuracy and stability. However, the application of wireless power transmission technology in the field of automated guided vehicle charging still faces challenges such as equipment size, system stability, and system efficiency. Summary of the invention

[0009] In view of the above-mentioned defects of the prior art, the present invention provides a dual-load wireless power transmission system. The dual-receiver design of the system enables it to achieve two-way stable constant voltage and constant current output without being equipped with a charge state detection and control circuit. It is easy to control, compact in structure, and highly stable, and is suitable for various power supply fields requiring multiple outputs.

[0010] The present invention provides a dual-load wireless power transmission system, comprising a primary circuit, a first receiver circuit and a second receiver circuit. The primary circuit and the first receiver circuit are combined to form a CLS-S structure, outputting a constant voltage output, and the primary circuit and the second receiver circuit are combined to form a CLC-CLC structure, outputting a constant current.

[0011] Furthermore, the primary circuit includes a transmitting coil L P The first receiver circuit includes a first receiving coil L SA The second receiver circuit includes a second receiving coil L SB , the transmitting coil L P The first receiving coil L comprises a solenoid coil and a Q-type coil which are wound vertically in series. SA Using a spiral coil structure, the second receiving coil L SB Using Q-type coil, the first receiving coil L SA and the second receiving coil L SB Vertical winding.

[0012] Furthermore, the transmitting coil comprises a transmitting side ferrite plate, the Q-type coil of the transmitting coil is wound on the surface of the transmitting side ferrite plate, and the solenoid coil is vertically wound on the transmitting side ferrite plate.

[0013] Furthermore, the dual-load wireless power transmission system includes a receiving-side ferrite plate, the second receiving coil L SB Wound on the surface of the ferrite plate on the receiving side, the first receiving coil L SA Wrapped vertically on the receiving side ferrite board.

[0014] Furthermore, the primary circuit includes a full-bridge inverter and a CLC compensation circuit.

[0015] Furthermore, the first receiver circuit includes a first full-bridge rectifier and a first receiver compensation capacitor C SA .

[0016] Furthermore, the second receiver circuit includes a second full-bridge rectifier and a CLC compensation circuit.

[0017] Compared with the prior art, the present invention has the following technical effects:

[0018] 1. The two-way transmission circuit of the present invention adopts CLC-S structure and CLC-CLC structure respectively, which can realize two-way constant voltage and constant current output that are independent of load, and the system works at a fixed frequency, avoiding the problem of low system stability caused by frequency bifurcation phenomenon;

[0019] 2. The present invention can automatically achieve constant voltage and constant current output in the dual output mode, without the need for primary and secondary wireless communication auxiliary circuits, charge state detection circuits and open circuit protection circuits. The circuit structure is simpler, the stability of the system is increased, the vehicle weight is reduced and no additional space is required.

[0020] 3. Due to the structural characteristics of the present invention, there is no need to add complex control algorithm modules, the system control is simple, and the system operation stability is high; it works under zero phase angle conditions during the entire charging process, avoiding reactive power loss and improving system efficiency.

[0021] 4. There is good electrical isolation between the two receiving sides of the system, ensuring the safety and reliability of the system.

[0022] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a circuit schematic diagram of a dual-load wireless power transmission system according to a specific embodiment of the present invention;

[0024] Figure 2 is an equivalent circuit diagram of a dual-load wireless power transmission system according to a specific embodiment of the present invention;

[0025] Figure 3 It is a schematic diagram of the magnetic flux distribution of two mutually perpendicular Q-coils and a solenoid coil;

[0026] Figure 4 It is a schematic diagram of the structure of the transmitting coil, the first receiving coil and the second receiving coil of the present invention;

[0027] Figure 5 is a graph of the output voltage of the first-stage receiving side, the output current of the second-stage receiving side and the input impedance angle of the system under different frequencies and different loads in a specific embodiment of the present invention, Figure 5 a is the output voltage curve of the first-stage receiving side. Figure 5 b is the output current curve of the second-stage receiving side. Figure 5 c is the curve diagram of input impedance angle;

[0028] Figure 6 is the normalized C of the present invention PThe impact on the two output currents and input impedance angle of the system, Figure 6 a is the output voltage change result of the first receiving side, Figure 6 b is the output voltage change result of the second receiving side, Figure 6 c is the equivalent resistance R L1 The input impedance angle changes as follows: Figure 6 d is the equivalent resistance R L2 Next, the input impedance angle changes.

[0029] Figure 7 is an output waveform under different loads in a specific embodiment of the present invention, Figure 7 a is the two loads R B1 =30Ω、R B2 =5Ω output waveform, Figure 7 b are two loads, R B1 =60Ω、R B2 =8Ω output waveform;

[0030] Figure 8 In a specific embodiment of the present invention, the primary compensation capacitor C P After slight modulation, the output waveform under different loads, Figure 8 a is the two loads R B1 =30Ω、R B2 =5Ω output waveform, Figure 8 b are two loads, R B1 =60Ω、R B2 =8Ω output waveform;

[0031] Fig. 9 In a specific embodiment of the present invention, the same load R B1 and R B2 The overall efficiency of the combination;

[0032] Fig.10 It is the distribution of power loss in various parts of the system under peak efficiency and load conditions. DETAILED DESCRIPTION

[0033] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0034] like Figure 1As shown, in a specific embodiment, a dual-load wireless power transmission system is provided, including a primary circuit, a first receiver circuit and a second receiver circuit.

[0035] The primary circuit includes a full-bridge inverter composed of switch tubes Q1, Q2, Q3 and Q4, a CLC compensation circuit and a transmitting coil L P The CLC compensation circuit includes a primary series compensation capacitor C1, a primary series compensation capacitor C P and parallel compensation inductor L1; the DC voltage source E and the full-bridge inverter are connected in parallel in sequence, one end of the primary series compensation capacitor C1 is connected to an output terminal A1 of the inverter circuit, and the other end of the primary series compensation capacitor C1 is connected to the primary series compensation capacitor C P One end of the primary side is connected in series with a compensation capacitor C P The other end is connected to the transmitting coil L P One end of the primary coil L P The other end of is connected to one end of the parallel compensation inductor L1 of the full-bridge inverter circuit, and the other end of the parallel compensation inductor L1 is connected to another output terminal A2.

[0036] The first receiver circuit includes a first receiving coil L SA , the first full-bridge rectifier composed of diodes D1, D2, D3 and D4, the first receiver compensation capacitor C SA and filter capacitor Co1, the first receiving coil L SA One end of the first receiver compensation capacitor C SA At one end, the first receiver compensation capacitor C SA The other end of the first receiving coil L is connected to an output end O1 of the first full-bridge rectifier. SA The other end is connected to the other output end O2 of the first full-bridge rectifier, the filter capacitor Co1 is connected in parallel with the first full-bridge rectifier, the first full-bridge rectifier circuit and the filter capacitor Co1 constitute a rectifier filter circuit, the primary circuit and the first receiver circuit are combined to form a CLS-S structure, outputting a constant voltage output to provide a constant voltage output for the load.

[0037] The second receiver circuit includes a second receiving coil L SB , a second full-bridge rectifier composed of diodes D5, D6, D7 and D8, a CLC compensation circuit and a filter capacitor Co2, wherein the CLC compensation circuit includes a series compensation capacitor C2, a series compensation capacitor C SB and parallel compensation inductor L2. The second receiving coil L SB One end of the second receiver is connected to the series compensation capacitor C SB The other end of the series compensation capacitor C2 is connected to an output terminal O3 of the full-bridge rectifier, and the other end of the series compensation capacitor C SBThe other end of the parallel compensation inductor L2 is connected to one end of the parallel compensation inductor L2, and the other end of the parallel compensation inductor L2 is connected to the second receiving coil L SB The other end of the full-bridge rectifier and the other output end O4 of the full-bridge rectifier, the filter capacitor Co2 is connected in parallel with the second full-bridge rectifier, the rectifier circuit and the filter capacitor Co2 constitute a rectifier filter circuit, the primary circuit and the second receiver circuit are combined to form a CLC-CLC structure, output a constant current, and provide a constant current output for the load.

[0038] Figure 1 In the equation, E is the system input DC voltage source, and M1, M2, and M3 represent the mutual inductances of the three coils. in is the output voltage phasor of HFI, U S1 and U S2 is the input voltage phasor of the rectifier. l ,I P ,I S1 ,I SB ,I S2 are the current phasors flowing through each grid. Each receiver is a full-bridge rectifier composed of four diodes (D1-D4) and (D5-D8), which converts the AC current I S1 ,I S2 Convert to DC B1 ,I B2 . R B1 and R B2 Is the equivalent resistance of the battery load. M1 is the transmitting side coil L P With the first receiver coil L SA The mutual inductance between them, M2 is the transmitting side coil L P With the second receiver coil L SB The mutual inductance between them, M3 is the first receiver coil L SA With the second receiver coil L SB The mutual inductance between them can eliminate unnecessary coupling (M3) due to the proposed decoupling structure.

[0039] like Figure 2 As shown in the figure, it is the equivalent circuit diagram of the constant current and constant voltage dual output WPT system. L1 and R L2 For R B1 and R B2 The rectifier input equivalent resistance, when the coil self-inductance (L P , L SA and L SB ) is compensated, the first receiver circuit is under the condition of CLC-S compensation circuit, R L1 Working like a constant voltage source, the second receiver is under the condition of CLC-CLC compensation circuit, R L2It works like a constant current source and can meet the constant output requirements of two different paths. L1 and R L2 Its mathematical expression is:

[0040] (1)

[0041] U in Relationship between the phase root mean square (RMS) and the input DC voltage source E, rectifier input current phase RMS: I S1 ,I S2 With the current I B1 and I B2 The mathematical relationship between them is expressed as:

[0042] (2)

[0043] According to Kirchhoff's voltage law (KVL), the following relationship expression can be listed:

[0044] (3)

[0045] To simplify the analysis, the corresponding impedance of the system can be defined as follows:

[0046] (4)

[0047] Where ω is the system resonant angular frequency. In order to achieve the ZPA condition, the circuit must be in a completely resonant state and must satisfy the following equation:

[0048] (5)

[0049] System first receiver output voltage U S1 The transconductance gain G VV and the second receiver output current I S2 The transconductance gain G VI It can be expressed as the following equation:

[0050] (6)

[0051] From (6), it can be seen that the output voltage and output current corresponding to the first receiver and the second receiver are both related to the load R L1 and R L2 Therefore, the system can achieve constant voltage and constant current output regardless of the load.

[0052] The input impedance of the inverter is Z in for:

[0053] (7)

[0054] From formula (7), we can get the input impedance Z in It is purely resistive, which means that the system can meet the ZPA condition, thereby reducing the reactive power loss of the system and improving the efficiency of the system.

[0055] like Figure 3 As shown, under the two mutually perpendicular Q-coils and solenoid coils, the Q-coil and the solenoid coil both generate magnetic fields scattered from the center, and their directions are perpendicular to each other. Among them, the magnetic flux direction of the red Q-coil is parallel to the XZ plane, and the magnetic flux direction of the blue solenoid coil is parallel to the YZ plane, indicating that the magnetic flux excited by the red Q-coil will not flow through the blue solenoid coil, and the magnetic flux excited by the blue solenoid coil will not flow through the red Q-coil. Therefore, the two mutually perpendicular Q-coils and the solenoid coil are magnetically decoupled. Since the mutual inductance between the transmitting coil and the second receiver coil of the dual-receiver system in the present application needs to be zero, the structure of the transmitting coil, the first receiving coil and the second receiving coil is provided in this embodiment as shown in FIG. Figure 4 shown.

[0056] As shown in the figure, the transmitting coil L P It includes a transmitting side ferrite plate and a solenoid coil and a Q-type coil which are connected in series and vertically wound. The Q-type coil of the transmitting coil is wound on the surface of the transmitting side ferrite plate, and the solenoid coil is vertically wound on the transmitting side ferrite plate.

[0057] The first receiving coil L SA Using a spiral coil structure, the second receiving coil L SB Using a Q-type coil, the second receiving coil L SB Wound on the surface of the ferrite plate on the receiving side, the first receiving coil L SA Vertically wound on the receiving side ferrite plate, the first receiving coil L SA and the second receiving coil L SB In this embodiment, the transmitting side coil L P Made of a wire wound around it, the first receiver coil L SA and the second receiver coil L SB Based on the above structure, since the first receiving side coil L SA and the second receiver coil L SB The magnetic fluxes do not flow through each other, so there is no cross coupling, and the mutual inductance M3 is 0.

[0058] In order to further verify the output characteristics of the dual-receiving-side decoupled constant-current and constant-voltage dual-output WPT system of the present invention, a simulation model is established in a specific embodiment, and its component parameters are shown in Table 1.

[0059] Table 1 Detailed theoretical circuit parameters

[0060]

[0061] According to the circuit element parameters designed in Table 1, the output voltage curve of the first receiving side, the output current curve of the second receiving side and the input impedance angle of the system under different frequencies and different loads are obtained as shown in the figure below: Figure 5 As shown. Figure 5 It can be seen that the system operates at a frequency of 85 kHz, and the first receiving side and the second receiving side respectively realize load-independent constant voltage output and constant current output under ZPA operation, which shows that a dual-load wireless power transmission system of this embodiment can meet the characteristic requirements of constant current and constant voltage dual-path output.

[0062] like Figure 6 As shown, the normalized C P The relationship between the two output currents and the input impedance angle of the system. As can be seen from the figure, the input impedance angle of the system is related to C P The normalized linear correlation is P Under the condition, as the load resistance changes, the output voltage and output current remain unchanged, and the corresponding C P The change can adjust the input phase angle. Therefore, by adjusting the compensation capacitor C P Fine-tuning can make the system weakly inductive, that is, by adjusting C P It can achieve zero voltage switching operation, reduce the conduction loss of MOSFETs in high-frequency inverters, and further improve system efficiency.

[0063] In this embodiment, relevant parameters of the magnetic coupler formed by the transmitting coil, the first receiving coil and the second receiving coil are shown in Table 2.

[0064] Table 2 Detailed dimensions of the proposed magnetic coupler

[0065]

[0066] According to the parameters in Table 3, a verification experimental prototype with an operating frequency of 85 kHz was built to verify the correctness of the proposed CC and CV dual-output WPT system. The CV output of the first receiver is 70 V, and the CC output of the second receiver is 3.5 A. The experimental prototype mainly includes: a DC voltage source E, a high-frequency inverter composed of four MOSFETs, the proposed magnetic coupler, and the transmitter-side compensation capacitors C1 and C P , transmitting side compensation inductor L1, first receiving coil compensation capacitor C SA , the second receiving coil compensation capacitor C SB and C2, compensation inductor L2, two rectifiers consisting of 8 fast recovery diodes, two battery loads R B1 and RB2 and oscilloscopes, numbered 1-16.

[0067] Table 3 Detailed theoretical circuit parameters

[0068]

[0069] When R B1 =30Ω、R B2 =5Ω and R B1 =60Ω、R B2 =8Ω, the experimental waveform obtained is as follows Figure 7 As shown, it can be seen that under different load conditions, the first receiver can achieve a CV output of 70 V, the second receiver can achieve a CC output of 3.5 A, and the ZPA condition is met.

[0070] The primary compensation capacitor C P The waveform after slight modulation is as follows Figure 8 As shown in the implementation waveform diagram, it can be seen that the system can achieve the CV output of the first receiver and the CC output of the second receiver under different load conditions and meet the ZVS condition, which means that zero voltage switching operation can be achieved only by adjusting the compensation capacitor Cp, which has the effect of reducing the switching loss of the system and improving the system efficiency.

[0071] like Fig. 9 As shown, it reflects the different load R B1 and R B2 The overall efficiency of the combination. The first receiving side load R B1 The second receiving side load R B2 There are 56 corresponding combinations when the load changes from 5Ω to 19Ω in 2Ω steps. It can be clearly seen that when the load on the first receiving side is 30Ω and the load on the second receiving side is 19Ω, the maximum output efficiency of the system is 92.6%.

[0072] By measuring the internal resistance of each component of the system and the resonant current flowing through them, the loss contribution of each component is obtained, and the power loss distribution of each part of the system under the corresponding peak efficiency and load conditions is obtained, as shown in the following example: Fig.10 As shown in the figure, HFI and rectifier account for a large part of the total loss, which means that the system can use semiconductor components with better performance to further improve the efficiency of the system.

[0073] In summary, the present invention enables the system to achieve constant voltage output and constant current output that are independent of the load, and does not require auxiliary circuits such as charge state detection circuits and wireless communication circuits. At the same time, the receiving side uses only a few compensation components, which meets the lightweight design requirements of the wireless charging system. And the input impedance Z of the system inIt is purely resistive, which means that the system can meet the ZPA condition and achieve high efficiency.

[0074] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A dual-load wireless power transmission system, characterized in that: It includes a primary circuit, a first receiver circuit and a second receiver circuit. The primary circuit and the first receiver circuit are combined to form a CLS-S structure to output a constant voltage output. The primary circuit and the second receiver circuit are combined to form a CLC-CLC structure to output a constant current.

2. The dual-load wireless power transmission system according to claim 1, characterized in that: The primary circuit includes a transmitting coil L P The first receiver circuit includes a first receiving coil L SA The second receiver circuit includes a second receiving coil L SB , the transmitting coil L P The first receiving coil L comprises a solenoid coil and a Q-type coil which are wound vertically in series. SA Using a spiral coil structure, the second receiving coil L SB Using Q-type coil, the first receiving coil L SA and the second receiving coil L SB Vertical winding.

3. The dual-load wireless power transmission system according to claim 2, characterized in that: The transmitting coil comprises a transmitting side ferrite plate, a Q-shaped coil of the transmitting coil is wound on the surface of the transmitting side ferrite plate, and a solenoid coil is vertically wound on the transmitting side ferrite plate.

4. The dual-load wireless power transmission system according to claim 2, characterized in that: The dual-load wireless power transmission system includes a receiving-side ferrite plate, the second receiving coil L SB Wound on the surface of the ferrite plate on the receiving side, the first receiving coil L SA Wrapped vertically on the receiving side ferrite board.

5. The dual-load wireless power transmission system according to claim 1, characterized in that: The primary circuit includes a full-bridge inverter and a CLC compensation circuit.

6. The dual-load wireless power transmission system according to claim 5, characterized in that: The first receiver circuit includes a first full-bridge rectifier and a first receiver compensation capacitor C SA .

7. The dual-load wireless power transmission system according to claim 5, characterized in that: The second receiver circuit includes a second full-bridge rectifier and a CLC compensation circuit.

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