A multi-coil single-transistor wireless power transmission circuit, system and control method

Abstract

The present invention provides a multi-coil single-transistor wireless power transmission circuit, system and control method, including a primary circuit and a secondary circuit, wherein the primary circuit includes multiple single-transistor resonant inverter wireless power transmitting circuits connected in parallel to a DC power supply, and the secondary circuit includes multiple wireless power receiving circuits corresponding one-to-one to the single-transistor resonant inverter wireless power transmitting circuits, wherein each of the single-transistor resonant inverter wireless power transmitting circuits includes an LC resonant circuit, an LCC compensation network and a transmitting coil, wherein: the LC resonant circuit includes a resonant inductor L connected in series between the two ends of the DC power supply; a and resonant capacitor C a , the resonant capacitor C a The switch tube Q is connected in parallel with the upper coil. Its effect is: reducing the sudden change of input current, enhancing system efficiency, and effectively eliminating the ripple of input current and partial circulating current between coils by controlling the phase shift of multi-coil excitation current, making the input current stable and improving the system power level.

Description

Technical Field

[0001] The present invention relates to wireless power transmission technology, and in particular to a multi-coil single-transistor wireless power transmission circuit, system and control method. Background Art

[0002] Wireless power transfer (WPT) technology enables energy transfer across air gaps without physical contact. Its inherent safety, speed, and flexibility make it considered a promising alternative to cable charging. Consequently, it has been widely adopted for powering consumer electronics, electric vehicles, specialized machinery, and medical electronics.

[0003] In wireless power transmission technology research, most studies targeting multi-coil parallel output are based on full-bridge or half-bridge topologies, but these all suffer from complex control and peripheral circuitry, as well as bridge arm direct-pass circuitry. In contrast, single-transistor resonant inverter circuits offer advantages such as high reliability, simple control, low cost, and ease of zero-voltage turn-on. However, they suffer from limitations such as limited transmission power and large system input current ripple. Therefore, connecting multiple transmitters in parallel and controlling the phase angle of the system input current to suppress ripple while increasing transmission power is an effective way to overcome the limitations of single-transistor resonant inverters. At the same transmission power, the overall system control scheme is simpler than that of a full-bridge topology.

[0004] Literature: Li Houji, Wang Chunfang, Yue Rui, et al. Research on single-switch wireless power transmission circuit based on SiC devices [J]. Proceedings of the CSEE, 2020, 40(06): 1808-1817. A wireless power transmission circuit based on a single-switch resonant inverter is disclosed. The SiC MOSFET is used to effectively improve the system efficiency, but the influence of the system input current on the system is not considered. In addition, due to the particularity of the single-switch resonant inverter, the conventional LCC resonant network cannot be directly applied. Some people have proposed the following method: Figure 1 The circuit structure shown in the figure is designed by adding an additional LC resonant circuit at the transmitting end to resonate, so that the LCC compensation network acts as a filter circuit, but its control process is as follows Figure 2 As shown in Figure 2, it can be found that the system input current of its single-tube LCC compensation network is severely distorted. Summary of the Invention

[0005] In light of this, the primary objective of this invention is to propose a multi-coil, single-transistor wireless power transmission circuit. By connecting a resonant capacitor in parallel with the switching transistor, the current oscillation at the system input is diverted to ground. This effectively improves the system input current waveform and reduces the total harmonic distortion (THD) of the system input current. Furthermore, by connecting multiple coils in parallel, the system's transmission power is increased, thereby improving system efficiency.

[0006] In order to achieve the above object, the specific technical solutions adopted by the present invention are as follows:

[0007] A multi-coil single-transistor wireless power transmission circuit includes a primary circuit and a secondary circuit. The key is that the primary circuit includes multiple single-transistor resonant inverter wireless power transmitting circuits connected in parallel to a DC power supply, and the secondary circuit includes multiple wireless power receiving circuits corresponding one-to-one to the single-transistor resonant inverter wireless power transmitting circuits. Each of the single-transistor resonant inverter wireless power transmitting circuits includes an LC resonant circuit, an LCC compensation network, and a transmitting coil, wherein: the LC resonant circuit includes a resonant inductor L connected in series between the two ends of the DC power supply. a and resonant capacitor C a , in the resonant capacitor C a The switch tube Q is connected in parallel with the LCC compensation network, and the front end of the LCC compensation network is connected to the resonant inductor L a The rear end of the LCC compensation network is connected to the transmitting coil L t Each wireless power receiving circuit is provided with a receiving coil corresponding to the transmitting coil, a secondary side compensation capacitor and a rectifier filter circuit.

[0008] Optionally, the single-tube resonant inverter wireless power transmitting circuit is provided with three paths, and the corresponding three transmitting coils are distributed in a triangular shape on the same plane.

[0009] Optionally, the output end of each wireless power receiving circuit is connected to a power load.

[0010] Optionally, the output ends of multiple wireless power receiving circuits are connected in parallel to the same power load.

[0011] Optionally, the switching tube is a SiC MOSFET tube.

[0012] Optionally, the LCC compensation network includes a compensation inductor L f , compensation capacitor C f and compensation capacitor C t , the compensation inductor L f and the compensation capacitor C f In series with the resonant capacitor C a Between the two ends of the compensation capacitor C t and the transmitting coil L t In series with the compensation capacitor C f Between the two ends of ω is the system operating angular frequency.

[0013] Based on the above circuit structure, the present invention also proposes a multi-coil single-transistor wireless power transmission system, comprising any of the multi-coil single-transistor wireless power transmission circuits described above and a PWM controller for controlling the switch tube Q, wherein a current sampling module is also connected to the PWM controller.

[0014] Optionally, the current sampling module is provided in the primary circuit and respectively collects the excitation current of each of the single-switch resonant inverter wireless power transmitting circuits.

[0015] Optionally, the current sampling module is arranged in the secondary circuit and collects the output current of each wireless power receiving circuit respectively, and then connects it to the PWM controller through the wireless communication module, and the PWM controller converts it into the excitation current of each single-tube resonant inverter wireless power transmitting circuit.

[0016] Based on the system described above, the present invention also provides a control method for the multi-coil single-transistor wireless power transmission system described above, the key of which is: when the single-transistor resonant inverter wireless power transmission circuit is provided with three paths, the PWM controller sets the phase shift conduction angle of the first path to 0°, the phase shift angle of the second path to α, and the phase shift conduction angle of the third path to β, and according to:

[0017] I in1 =-(I in2 ×cosα+I in3 ×cosβ)-I in2 × sinα=I in3 ×sinβ

[0018] The constraint relationship is controlled, where I in1 It represents the excitation current of the first single-tube resonant inverter wireless power transmission circuit, I in2 It represents the excitation current of the second single-tube resonant inverter wireless power transmission circuit, I in3 Represents the excitation current of the second single-tube resonant inverter wireless power transmission circuit.

[0019] The effects of the present invention are:

[0020] (1) The resonant capacitor C a Connecting it in parallel with the switch tube can effectively improve the waveform of the input current and reduce the sudden change of the input current.

[0021] (2) Resonant inductor L a The current flowing through L a Inversely proportional, increase L a The value of can effectively reduce the current flowing through it and enhance the system efficiency;

[0022] (3) By controlling the phase shift of the multi-coil excitation current, the ripple of the input current and the partial circulating current between the coils can be effectively eliminated, making the input current stable and improving the system power level. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific implementation of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the specific implementation or the description of the prior art.

[0024] Figure 1 It is the LCC compensation network structure of the single-transistor resonant inverter in the prior art;

[0025] Figure 2 for Figure 1 The working mode waveform of the circuit shown;

[0026] Figure 3 This is the LCC compensation network structure of the single-switch resonant inverter proposed by the present invention;

[0027] Figure 4 for Figure 3 The working mode waveform of the circuit shown;

[0028] Figure 5 is the resonant inductor L a The relationship between the value and the current flowing through the graph;

[0029] Figure 6 For different resonant capacitors C a Soft switching waveform diagram;

[0030] Figure 7 The AC voltage U input to the LCC compensation network in Waveform graph;

[0031] Figure 8 This is a schematic diagram of a multi-coil single-transistor wireless power transmission circuit proposed in a specific embodiment of the present invention;

[0032] Figure 9 A diagram showing the distribution relationship and size design of multiple coils in a specific embodiment of the present invention;

[0033] Figure 10 for Figure 8 Equivalent circuit model diagram;

[0034] Figure 11 This is a schematic diagram of a multi-coil single-tube wireless power transmission system in a specific embodiment of the present invention;

[0035] Figure 12 This is a comparison of the input current before and after the LCC compensation network of the traditional single-transistor resonant inverter is phase-shifted by 120°;

[0036] Figure 13 This is a comparison diagram of the input current before and after the LCC compensation network of the single-transistor resonant inverter of the present invention is phase-shifted by 120°;

[0037] Figure 14 The comparison diagram of input current before and after phase shift when coupling coefficients M1=50uH, M2=46.4uH, and M3=42uH are shown;

[0038] Figure 15 is the load R L1 =10Ω、R L2 =5Ω、R L3 =15Ω input current comparison before and after phase shift. DETAILED DESCRIPTION

[0039] The following embodiments of the technical solution of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention and are therefore only examples and are not intended to limit the scope of protection of the present invention.

[0040] It should be noted that, unless otherwise specified, the technical or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0041] like Figure 3 As shown, this embodiment first provides a single-transistor resonant inverter wireless power transmission circuit, including an LC resonant circuit, an LCC compensation network and a transmitting coil, wherein: the LC resonant circuit includes a resonant inductor L connected in series between the two ends of the DC power supply a and resonant capacitor C a , in the resonant capacitor C a The switch tube Q is connected in parallel with the LCC compensation network, and the front end of the LCC compensation network is connected to the resonant inductor L a The rear end of the LCC compensation network is connected to the transmitting coil L t In the specific implementation, the switch tube is SiC MOSFET tube, and the LCC compensation network includes the compensation inductor L f , compensation capacitor C f and compensation capacitor C t , the compensation inductor L f and the compensation capacitor C f In series with the resonant capacitor C a Between the two ends of the compensation capacitor C t and the transmitting coil L t In series with the compensation capacitor C f between the two ends.

[0042] Combine Figures 1-4 Conduct comparative analysis in Figure 2 and Figure 4 In, Vgs is the driving voltage of the switch tube, I La is the resonant inductor current, I1 is the transmitter compensation inductor current, V ds is the voltage across the switch tube;

[0043] pass Figure 2 It can be seen that the working mode of the traditional LCC compensation network is:

[0044] Mode 1 [t0-t1]: At t0, the switch is turned on and the resonant inductor current I La Increase linearly. Resonant capacitor C a Equivalent to a short circuit, the transmitter compensation inductor current I1 gradually decreases and crosses zero at time t1.

[0045] Mode 2 [t1-t2]: At time t1, the control switch is turned off, and the system input current I in Rapidly drops to zero, the transmitting end inductor current I1 increases in the reverse direction, and the transmitting coil current I t Continue to drop to zero.

[0046] Mode 3 [t2-t3]: At time t2, the resonant inductor current I La Reduced to zero, the transmitter compensates the inductor current I1 and the transmitting coil current I t Reverse increase, V ds Reached maximum value.

[0047] Mode 4 [t3-t4]: At t3, the resonant inductor current I La The reverse direction increases, and the transmitter inductor current I1 decreases to zero.

[0048] Mode 5 [t4-t5]: At time t4, the system input current I in After a rapid reverse increase, it begins to decrease. The resonant inductor current I La The inductor current I1 at the transmitter increases in a positive direction after crossing zero. ds The voltage is zero and the switch tube enters the soft switching state.

[0049] Mode 6 [t5-t6]: At t5, the control switch is turned on, and the system input current I in , resonant inductor current I La and the transmitter compensation inductor current I La The transmitting coil current I t Decrease in the opposite direction to zero.

[0050] Mode 7 [t6-t0]: At t6, the system input current I in , resonant inductor current I La Transmitter compensation inductor current I LaIncreasing in the positive direction, the transmitting coil current I t Positive increase.

[0051] The present invention changes the connection mode of the LC resonant circuit and the switch tube. Figure 4 It can be seen that its working mode is:

[0052] Mode 1 [t0-t1]: is the same as the working mode 1 of the traditional LCC compensation network and will not be described in detail here.

[0053] Mode 2 [t1-t2]: At time t1, the control switch is turned off, and the system input current I in Starts to decrease, the transmitting end inductor current I1 increases in the opposite direction, and the transmitting coil current I t Continue to drop to zero.

[0054] Mode 3 [t2-t3]: At time t2, the system input current I in Increases to the maximum value, the resonant inductor current I La Reduced to zero, the transmitter compensates the inductor current I1 and the transmitting coil current I t Reverse increase, V ds Reached maximum value.

[0055] Mode 4 [t3-t4]: At time t3, the system input current I in The resonant inductor current I La The reverse direction increases, and the transmitter inductor current I1 decreases to zero.

[0056] Mode 5 [t4-t5]: At time t4, the system input current I in The resonant inductor current I La The inductor current I1 at the transmitter increases in a positive direction after crossing zero. ds The voltage is zero and the switch tube enters the soft switching state.

[0057] Mode six [t5-t6]: Same as the working mode six of the traditional LCC compensation network.

[0058] Mode seven [t6-t0]: Same as the working mode seven of the traditional LCC compensation network.

[0059] It can be seen that the working difference between the two different compensation networks is only reflected in the input current. The single-switch resonant inverter LCC compensation network proposed in this invention effectively improves the system input current waveform, can be used for multi-coil phase shifting to suppress excitation current harmonics, and can reduce the loss of high-frequency components and front-end buck-boost circuits caused by current shock.

[0060] For the single-tube resonant inverter wireless power transmission circuit provided by the present invention, the resonant inductor L in steady state isa The energy stored in one cycle is is a fixed value, when the inductance L a When the value is small, the current I La Increase, resulting in the inductance L a The loss and voltage stress of the switch tube increase. a When L is large, the switch tube cannot achieve soft switching. Therefore, in order to ensure both system efficiency and soft switching margin, it is necessary to reasonably design L a and C a parameter.

[0061] By Figure 5 It can be seen that when L a When the current exceeds 18μH, the decreasing trend of the current will no longer be obvious, so L a The value is 18μH.

[0062] When the resonant inductor L a After the value of the resonant capacitor C is determined, a The value of Figure 6 As shown, when C a When the capacitance is less than 85nF, the system will experience secondary oscillation, which will affect the system efficiency. In order to ensure the soft switching margin of the system, C a The value of is selected as 85nF.

[0063] At the same time, the LCC compensation network inputs the AC voltage U in one cycle in Waveform Figure 7 As shown in part (a). Resonant inductor L a The voltages at both ends are periodic square wave voltage and half-sine wave voltage. According to the area equivalence rule, U in The waveform is equivalent to Figure 7 As shown in part (b).

[0064] Depend on Figure 7 Part (b) gives the equivalent AC voltage as:

[0065]

[0066] According to the inductor volt-second balance, the inductor voltage is zero during one cycle, that is:

[0067]

[0068] The solution is:

[0069] Where D is the duty cycle, D = 0.5; t ZVS is the soft switching margin.

[0070] In combination with the above analysis, this embodiment provides a Figure 8The multi-coil single-tube wireless power transmission circuit shown includes a primary circuit and a secondary circuit. The primary circuit includes three single-tube resonant inverter wireless power transmitting circuits connected in parallel to a DC power supply. The secondary circuit includes three wireless power receiving circuits corresponding one to one to the single-tube resonant inverter wireless power transmitting circuit. Each of the wireless power receiving circuits is provided with a receiving coil corresponding to the transmitting coil, a secondary compensation capacitor, and a rectifier filter circuit. The output ends of the three wireless power receiving circuits are connected in parallel to the same power load. Of course, during implementation, the output end of each wireless power receiving circuit can also be connected to a power load according to the requirements of the application scenario.

[0071] pass Figure 9 It can be seen that the corresponding three transmitting coils are distributed in a triangle on the same plane. In specific implementation, the distance between the transmitting coil and the receiving coil is 50mm, the length and width of the ferrite are both 160mm, and the thickness is 2mm. The coil is wound with 0.1mm×150 strands of Litz wire. Figure 8 As can be seen from the multi-coil single-tube wireless power transmission circuit shown, V DC It is the input DC voltage of the single-transistor resonant inverter; Q1~Q3 are SiC MOSFETs; L f1 ~L f3 Compensation inductance for the transmitter; C f1 ~C f3 L is the parallel compensation capacitor at the transmitter end; t1 ~L t3 is the transmitting coil; C t1 ~C t3 L is the compensation capacitor in series with the transmitter; f1 ~L f3 、C f1 ~C f3 、C t1 ~C t3 、L t1 ~L t3 They constitute the LCC filter circuit at the transmitting end; R t1 ~R t3 is the internal resistance of the transmitting coil; L a1 ~L a3 is the resonant inductance; C a1 ~C a3 is the resonant capacitor; M1~M3 are the mutual inductances between the coupled coils; L r1 ~L r3 is the receiving coil; R r1 ~R r3 is the internal resistance of the receiving coil; C r1 ~C r3 is the compensation capacitor of the receiving coil; D1~D3 are the rectifier bridge; C L1 ~CL3 is the output filter capacitor; R L is the load resistance. in1 ~I in3 is the input current of each inverter unit; I in is the system input current; I t1 ~I t3 is the transmitting coil excitation current.

[0072] Combined with the previous analysis, the output impedance of each subsystem is:

[0073]

[0074] Due to the good high-order filtering characteristics of the compensation network, the system can be analyzed using the harmonic approximation method. The system equivalent circuit is as follows: Figure 10 To simplify the analysis, when the transmitting coils are far apart, the cross-coupling between the coils on the same side can be ignored.

[0075] According to Kirchhoff's voltage law, Figure 10 The KCL and KVL equations of the LCC-S circuit model are shown in formula (5):

[0076]

[0077] According to the working characteristics of LCC, when the system resonates, the input impedance Z in When it is purely resistive, that is, the imaginary part is zero, the following relationship exists:

[0078]

[0079] Obtain:

[0080]

[0081] From formula (7), the rectifier input voltage V of each subsystem is o1 、V o2 and V o3 They are:

[0082]

[0083] And V o1 =V o2 =V o3 , and we get:

[0084]

[0085] Therefore, the voltage gains G1, G2, and G3 of each subsystem can be derived as follows:

[0086]

[0087] From formula (10), we can see that the voltage gain G and the compensation inductance L f , mutual inductance M and equivalent load are related to the internal resistance of the receiving coil.

[0088] From equations (4) and (7), the mutual inductances M1, M2, and M3 between the coils are:

[0089]

[0090] In order to achieve harmonic suppression of the input current, it can be seen from formula (7) that the current I output by the DC source in for:

[0091]

[0092] According to formula (12), the input current I of each phase subsystem can be obtained in1 , I in2 , I in3 The input current is decomposed into the DC component, fundamental wave and the superposition of each harmonic using fast Fourier transform.

[0093] Decompose the excitation current I of each module according to the fast Fourier transform in1 , I in2 , I in3 The fundamental wave is phase-shifted and suppressed according to the vector analysis shown in equation (13).

[0094] I in1 =-(I in2 ×cosα+I in3 ×cosβ)-I in2 × sinα=I in3 ×sinβ (13)

[0095] Let I in1 The phase shift angle is zero degrees, then α and β are I in2 , I in3 The phase shift angle.

[0096] Therefore, as an embodiment, Figure 11 As shown, this embodiment provides a multi-coil single-tube wireless power transmission system, including the multi-coil single-tube wireless power transmission circuit described above and a PWM controller for controlling the switch tube Q. A current sampling module is also connected to the PWM controller. In this embodiment, the current sampling module is arranged in the primary circuit and respectively collects the excitation current of each single-tube resonant inverter wireless power transmission circuit.

[0097] During the transmission process, the total output current of the DC source is controlled by adjusting the coil phase shift conduction angles α and β, so that the ripple of the total current is minimized, thereby making the overall efficiency higher.

[0098] In the actual system, a single-transistor wireless power transmission subsystem is selected as a benchmark, and its conduction angle is set to 0. The remaining two control degrees of freedom α and β can be calculated according to formula (13).

[0099] As another embodiment, the current sampling module can also be arranged in the secondary circuit and collect the output current of each wireless power receiving circuit respectively, and then connected to the PWM controller through the wireless communication module, and converted by the PWM controller into the excitation current of each single-tube resonant inverter wireless power transmitting circuit.

[0100] Based on the description of the above system, it can be seen that this embodiment also provides a control method for a multi-coil single-tube wireless power transmission system. When the single-tube resonant inverter wireless power transmission circuit is provided with three paths, the PWM controller sets the phase shift conduction angle of the first path to 0°, the phase shift angle of the second path to α, and the phase shift conduction angle of the third path to β, and according to:

[0101] I in1 =-(I in2 ×cosα+I in3 ×cosβ)-I in2 × sinα=I in3 ×sinβ

[0102] The constraint relationship is controlled, where I in1 It represents the excitation current of the first single-tube resonant inverter wireless power transmission circuit, I in2 It represents the excitation current of the second single-tube resonant inverter wireless power transmission circuit, I in3 Represents the excitation current of the second single-tube resonant inverter wireless power transmission circuit.

[0103] To verify the effectiveness of the present invention, a multi-coil parallel transmission simulation model was built using MATLAB / Simulink software, with parameters shown in Table 1. The system switching frequency is 100kHz, the switch duty cycle is 0.5, and the output voltage is 23.6V.

[0104] Table 1 Parameters of single-tube WPT system prototype

[0105]

[0106]

[0107] (1) Verification of subsystem balanced coupling simulation results

[0108] First, the parameters of all subsystems are set to be consistent. Under all balanced coupling conditions, the input current I before and after the phase shift of the LCC compensation network of the traditional single-transistor resonant inverter isin like Figure 12 When all subsystems are turned on simultaneously, the input current shows severe abrupt changes, with a THD of 47.1%, a DC component of 7.5A, a fundamental RMS value of 7.7A, and an output power of 166.5W. When all subsystems are turned on sequentially with a 120° phase shift, although the current amplitude is significantly reduced, the current abrupt changes are not improved, with a THD of 61.1%, a DC component of 7.4A, and a fundamental RMS value of 1.9A. The output power is also 166.5W.

[0109] The input current I of all subsystems of the LCC compensation network of the single-tube resonant inverter of the present invention is simultaneously turned on in like Figure 13 As shown, the THD is 32.8%, the DC component is 7.4A, the fundamental RMS value is 11.4A, and the output power is 166.5W. After all subsystems are phase-shifted 120° and turned on, the current waveform is smooth, with a THD of 6.1%, a DC component of 7.4A, and a fundamental RMS value of 0.68A. The output power is 166.5W.

[0110] (2) Verification of subsystem unbalanced coupling simulation results

[0111] Set the coupling coefficients of the subsystems to be M1 = 50uH, M2 = 46.4uH, and M3 = 42uH, respectively. Make the subsystems unbalancedly coupled. According to formula (13), the input current I is obtained. in1 , I in2 , I in3 The optimal phase shift angles are 0°, 125.7°, and 239.7°. The input current I before and after phase shift in like Figure 14 As shown in the figure, the THD is 32.9%, the DC component is 7.4A, the fundamental RMS value is 11.2A, and the output power is 165.2W. After all subsystems are phase-shifted and turned on, the input current has a THD of 9.7%, a DC component of 7.5A, and a fundamental RMS value of 0.66A. The output power is 165.3W.

[0112] (3) Verification of subsystem unbalanced load simulation results

[0113] Set the subsystem loads to R L1 =10Ω、R L2 =5Ω、R L3 =15Ω. Make the subsystem work with unbalanced load. According to formula (13), the input current I is obtained in1 , I in2 , I in3 The phase shift angles are 0°, 223.1°, and 91.9°. The input current I before and after phase shift in like Figure 15As shown in the figure, the THD is 30.2%, the DC component is 8.6A, the fundamental RMS value is 11.9A, and the output power is 190.1W. After phase-shift conduction, the input current has a DC component of 8.5A and a fundamental RMS value of 0.6A, and the output power is 190.3W.

[0114] In summary, the multi-coil single-transistor wireless power transmission circuit, system and control method proposed in the present invention are based on eliminating the ripple of the input current in the wireless power transmission of the single-transistor resonant inverter. A novel circuit structure is determined through modal analysis. The circuit uses the resonant capacitor C a Moving it down to parallel with the switch tube can effectively improve the waveform of the input current and reduce the sudden change of the input current. At the same time, due to the resonant inductor L a The current flowing through L a Inversely proportional, increase L a The value of can effectively reduce the current flowing through it and enhance the system efficiency. In addition, by controlling the phase shift of the multi-coil excitation current, the ripple of the input current and the partial circulating current between the coils can be effectively eliminated, making the input current stable and improving the system efficiency and power level.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and such changes should be included in the scope of the claims and description of the present invention.

Claims

1. A multi-coil single-transistor wireless power transmission circuit, comprising a primary circuit and a secondary circuit, characterized in that: The primary circuit includes three single-tube resonant inverter wireless power transmitting circuits connected in parallel to a DC power supply, and the secondary circuit includes three wireless power receiving circuits corresponding to the single-tube resonant inverter wireless power transmitting circuits. Each of the single-tube resonant inverter wireless power transmitting circuits includes an LC resonant circuit, an LCC compensation network, and a transmitting coil, wherein: the LC resonant circuit includes a resonant inductor L connected in series between the two ends of the DC power supply. a and resonant capacitor C a , in the resonant capacitor C a The switch tube Q is connected in parallel with the LCC compensation network, and the front end of the LCC compensation network is connected to the resonant inductor L a The rear end of the LCC compensation network is connected to the transmitting coil L t Each wireless power receiving circuit is provided with a receiving coil corresponding to the transmitting coil, a secondary side compensation capacitor and a rectifier filter circuit; The three transmitting coils corresponding to the single-tube resonant inverter wireless power transmitting circuit are triangularly distributed on the same plane; the switch tube Q is controlled by a PWM controller, and the PWM controller sets the phase shift conduction angle of the first path to 0°, the phase shift angle of the second path to α, and the phase shift conduction angle of the third path to β, and according to: I in1 =-(I in2 ×cosα+I in3 ×cosβ)-I in2 ×sinα=I in3 ×sinβ The constraint relationship is controlled, where I in1 It represents the excitation current of the first single-tube resonant inverter wireless power transmission circuit, I in2 It represents the excitation current of the second single-tube resonant inverter wireless power transmission circuit, I in3 It represents the excitation current of the third single-tube resonant inverter wireless power transmission circuit.

2. The multi-coil single-transistor wireless power transmission circuit according to claim 1, characterized in that: The output end of each wireless power receiving circuit is connected to an electrical load.

3. The multi-coil single-transistor wireless power transmission circuit according to claim 1, characterized in that: The output ends of the three wireless power receiving circuits are connected in parallel to the same power load.

4. The multi-coil single-transistor wireless power transmission circuit according to claim 1, characterized in that: The switch tube is a SiC MOSFET tube.

5. The multi-coil single-transistor wireless power transmission circuit according to claim 1, characterized in that: The LCC compensation network includes a compensation inductor L f , compensation capacitor C f and compensation capacitor C t , the compensation inductor L f and the compensation capacitor C f In series with the resonant capacitor C a Between the two ends of the compensation capacitor C t and the transmitting coil L t In series with the compensation capacitor C f Between the two ends of ω is the system operating angular frequency.

6. A multi-coil single-tube wireless power transmission system, characterized in that: It comprises the multi-coil single-transistor wireless power transmission circuit according to any one of claims 1 to 5, and a current sampling module is further connected to the PWM controller.

7. The multi-coil single-transistor wireless power transmission system according to claim 6, characterized in that: The current sampling module is arranged in the primary circuit and respectively collects the excitation current of each single-tube resonant inverter wireless power transmission circuit.

8. The multi-coil single-transistor wireless power transmission system according to claim 6, characterized in that: The current sampling module is arranged in the secondary circuit and collects the output current of each wireless power receiving circuit respectively, and then connects it to the PWM controller through the wireless communication module, and the PWM controller converts it into the excitation current of each single-tube resonant inverter wireless power transmitting circuit.

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