Dual-load automatic guided vehicle wireless charging system with anti-offset characteristic

Abstract

The invention discloses a dual-load automatic guided vehicle wireless charging system with an anti-offset characteristic, and belongs to the technical field of wireless power transmission. The system comprises a high-frequency full-bridge inverter, an LCC-S resonance compensation network, an orthogonal DD coil, a full-bridge rectifier and an external element. A transmitting coil and a receiving coil respectively adopt a winding method with dense outside and sparse inside and a winding method with sparse outside and dense inside, orthogonal magnetic field coupling is enhanced in combination with a ferrite magnetic core, and efficient cooperative power supply of a single power supply to double receiving loads and system stability are effectively guaranteed. The LCC-S network realizes bilateral resonance and zero phase angle input of the system through configuration of a plurality of independent capacitors and inductors, provides constant voltage output and inhibits multi-load crosstalk. Compared with the prior art, the problems of weak anti-offset capability, large multi-load interference, sudden efficiency drop and the like of a traditional scheme are effectively solved, and the coupling coefficient gt is within the offset range of + / -20cm; 0.25, the transmission efficiency is stable gt; double-AGV parallel charging is supported, and the voltage fluctuation is lt when a single load exits; and the system stability and the multi-machine cooperation capability are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wireless power transmission, and particularly relates to a dual-load automatic guided vehicle wireless charging system with anti-offset characteristics. BACKGROUND

[0002] The traditional automatic guided vehicle relies on contact charging or manual battery replacement, and has problems such as mechanical wear, electric spark, high maintenance cost and low work efficiency, and has been difficult to meet the 7x24 hour unattended operation demand. At present, the wireless charging system for the automatic guided vehicle mainly adopts the magnetic coupling resonance type technology, and its typical architecture includes a high-frequency inverter, a transmitting coil, a receiving coil, a compensation network and a rectification and stabilization module. However, due to the factors such as the driving path error of the automatic guided vehicle, the parking precision fluctuation and the ground flatness, there is often a transverse or longitudinal offset between the transmitting coil and the receiving coil, which leads to a decrease in the system coupling coefficient, a drop in the transmission power and a significant reduction in the efficiency. In addition, the existing scheme mostly adopts a single coil structure or a simple series-series (SS) / series-parallel (SP) compensation topology, and has weak anti-offset ability, and the efficiency drops to below 50% under the offset condition of ±10 cm, and even causes safety hazards such as inverter overcurrent and coil overheating. At the same time, although the traditional double-D (DD) coil has good anti-offset potential, the winding arrangement, magnetic core configuration and inter-turn coupling optimization method are not mature, which leads to a large volume and high weight of the coil, and it is difficult to meet the requirements of the automatic guided vehicle chassis space and lightweight. Therefore, it is necessary to design an automatic guided vehicle wireless charging system with high anti-offset ability, lightweight structure, high efficiency and multi-machine parallel charging capacity, so as to solve the above technical problems and promote the large-scale application of the automatic guided vehicle wireless charging technology. SUMMARY

[0003] The purpose of the application is to design a dual-load automatic guided vehicle wireless charging system with anti-offset characteristics. To achieve the above purpose, the technical scheme adopted by the application is as follows: The dual-load automatic guided vehicle wireless charging system with anti-offset characteristics comprises one high-frequency full-bridge inverter, an LCC-S resonance compensation network, a DD coil, two full-bridge rectifiers and two independent external inductors L p1 、 L p2 、 six independent external capacitors C e1 、 C e2 、 C e3 、 C e4 ,C p3 、 C p4 , 2 load resistors R L3 、 R L4 The input DC voltage of the inverter is U dc , the operating angle frequency is ω , and the output fundamental voltage is U .

[0004] The DD coil magnetic coupling mechanism adopts two D-shaped coils arranged side by side, two pairs of DD coils are symmetrically arranged, and are arranged in 90° orthogonal arrangement, and decoupling is realized by orthogonal decomposition of magnetic field vectors. The D-shaped coil is formed by symmetrically distributing two rectangular or semicircular windings, with an outer diameter of 20 cm, an inner diameter of 10 cm, and a 5 cm installation allowance reserved in the inner diameter part. The transmitting end coil T X1 、 T X2 Adopting coplanar "outer dense inner sparse" winding: outer contour 20cmx10cm, inner opening 15cmx5cm, front 4 turns densely wound, rear 4 turns sparsely wound (spare winding distance 2mm), single coil inductance 18µH, number of turns 8 turns. The receiving end coil R X1 、 R X2 is "outer sparse inner dense" winding symmetric with the transmitting end, with the same size and a 3cm installation gap. The transmitting coil adopts "outer dense inner sparse" winding, and the receiving coil adopts "outer sparse inner dense" winding to reduce high-frequency eddy current loss and improve the anti-offset performance of the system. The back of the coil is attached to a ferrite core, which directionally constrains the magnetic force line, reduces the leakage and eddy current loss, improves the coupling coefficient, shields the electromagnetic interference of the metal components behind, enhances the anti-offset ability and transmission efficiency.

[0005] The coupling mechanism parameters are calculated and optimized by finite element simulation software. First, the self-inductance of the transmitting end and receiving end coils and the mutual inductance between them are obtained, and then the coupling coefficient is determined by the following formula: In the formula, M is the mutual inductance, L 1, L 2 are the self-inductance of the transmitting end and the receiving end, respectively.

[0006] In the simulation process, the self-induction and mutual induction data of the single transmitting coil and the single receiving coil were recorded. The results showed that the mutual induction between the non-target coils was significantly weakened after adopting the orthogonal double-D structure, which verified the decoupling effect of the structure. Further optimization of the anti-offset performance of the system showed that when the X-axis or Y-axis direction offset was 0-20 cm, the main coupling mutual induction only had a small fluctuation, and when the offset was 10 cm, it had a slight rise, and then gradually decreased with the increase of the offset. The overall change range was small. The results showed that the winding method and the orthogonal layout could effectively ensure the stability of the wireless charging system.

[0007] The LCC-S resonance compensation network is two transmitting coils T X1 、 T X2 The three independent compensation elements of the LCC-S resonance compensation network are connected in series between the transmitting coil and the positive output terminal of the inverter; the capacitor C e1 is connected in parallel between the transmitting coil and the positive input terminal of the rectifier T X1 The three independent compensation elements of the LCC-S resonance compensation network are connected in series between the transmitting coil and the positive output terminal of the inverter; the capacitor C p1 is connected in parallel between the transmitting coil and the positive input terminal of the rectifier T X1 The three independent compensation elements of the LCC-S resonance compensation network are connected in series between the transmitting coil and the positive output terminal of the inverter; the capacitor C e1 is connected in parallel between the transmitting coil and the positive input terminal of the rectifier C e2 The three independent compensation elements of the LCC-S resonance compensation network are connected in series between the transmitting coil and the positive output terminal of the inverter; the capacitor R X1 is connected in parallel between the transmitting coil and the positive input terminal of the rectifier C e3 The three independent compensation elements of the LCC-S resonance compensation network are connected in series between the transmitting coil and the positive output terminal of the inverter; the capacitor T X2 is connected in parallel between the transmitting coil and the positive input terminal of the rectifier C p2 The three independent compensation elements of the LCC-S resonance compensation network are connected in series between the transmitting coil and the positive output terminal of the inverter; the capacitor T X2 is connected in parallel between the transmitting coil and the positive input terminal of the rectifier C e3 The three independent compensation elements of the LCC-S resonance compensation network are connected in series between the transmitting coil and the positive output terminal of the inverter; the capacitor C e4 is connected in parallel between the transmitting coil and the positive input terminal of the rectifier R X2 The three independent compensation elements of the LCC-S resonance compensation network are connected in series between the transmitting coil and the positive output terminal of the inverter; the capacitor The LCC compensation part of the LCC-S resonance compensation network is composed of independent impedance elements C e1 、 C e3 、 C p1 、 C p2 and the transmitting coilT X1 、 T X2 constituted, wherein C e1 one end is connected with the positive end of the inverter output, and the other end is connected with the transmitting coil T X1 ; C p1 parallelly connected at two ends of the transmitting coil T X1 and C e1 the transmitting coil T X1 the other end is connected with the negative end of the inverter output. C e3 one end is connected with the positive end of the inverter output, and the other end is connected with the transmitting coil T X2 ; C p2 parallelly connected at two ends of the transmitting coil T X2 and C e3 the transmitting coil T X2 the other end is connected with the negative end of the inverter output.

[0008] The independent impedance element of the S-S compensation part of the LCC-S resonance compensation network C e2 one end of which is connected with the receiving coil R X1 close to the rectifier, and the other end is connected with the positive potential end of the rectifier input voltage; the independent impedance element C e4 one end of which is connected with the receiving coil R X2 close to the rectifier, and the other end is connected with the positive potential end of the rectifier input voltage.

[0009] The KVL is added to the coupling two-side loop respectively, and the following voltage equation set is established: The input impedance expression of the whole main loop is obtained: wherein the equivalent impedance of the receiving end is: The receiving end output voltage is: Through algebraic elimination, combined with the mutual inductance coupling relationship, the whole voltage gain expression can be derived as follows: The system effective power is: The efficiency is defined as: To achieve high efficiency operation of the system, the LCC compensation network needs to meet the following resonance conditions: When the above conditions are met, the system reaches a bilateral resonance state, which can achieve zero phase angle input and improve energy transmission efficiency.

[0010] Under the action of lateral offset Δ x The coupling coefficient k Will decrease, and the mutual inductance M Can be expressed as: Where k (Δ x ) can be fitted by simulation as a Gaussian decay function: The LCC-S resonance compensation network is configured to: When the inverter output angular frequency ω satisfies: The system enters a bilateral resonance state, achieving zero phase angle input and constant voltage output.

[0011] Compared with the prior art, the DD type magnetic coupling mechanism and the LCC-S compensation network are deeply integrated, the spatial orthogonal magnetic field is generated by the differential winding of the transmitting end outer dense and inner sparse and the receiving end outer sparse and inner dense, and the constant voltage-current composite characteristics of the LCC-S topology are used, so that the magnetic coupling coefficient k > 0.25 is maintained within the offset range of ±20cm, and the system efficiency is stabilized at more than 85%; the cross-coupling mutual inductance is converted into controllable impedance through the series-parallel resonance network of LCC-S, eliminating the energy cross-talk between multiple loads; the compensation inductance and capacitance are used to resonate with the self-inductance and mutual inductance of the coil respectively, and the cross-coupling on the same side and the opposite side is offset, realizing power self-balancing when two automatic guided vehicles are charging at the same time, and when any load is disconnected, the voltage fluctuation of the remaining load is less than ±3%, which can be seamlessly extended to the cluster automatic guided vehicle wireless charging scene of any number of loads.

[0012] The embodiments will be described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1A topology of a wireless charging system of a dual-load automatic guided vehicle with anti-offset characteristic Figure 2 A coupling mechanism of a wireless charging system of a dual-load automatic guided vehicle with anti-offset characteristic Figure 3 A coupling mechanism of a wireless charging system of a dual-load automatic guided vehicle with anti-offset characteristic Figure 4 A coupling mechanism of a wireless charging system of a dual-load automatic guided vehicle with anti-offset characteristic L 1 、L 2Mutual inductance changes with x offset amount image Figure 5 A coupling mechanism of a wireless charging system of a dual-load automatic guided vehicle with anti-offset characteristic L 1 L 2 Mutual inductance changes with y offset amount image Figure 6 A coupling mechanism of a wireless charging system of a dual-load automatic guided vehicle with anti-offset characteristic Figure 7 A coupling mechanism of a wireless charging system of a dual-load automatic guided vehicle with anti-offset characteristic R L Load size and efficiency relationship

[0014] Specific implementation mode The application will be further described below in conjunction with the drawings and specific implementation modes.

[0015] As Figure 1 shown, the wireless charging system of a dual-load automatic guided vehicle with anti-offset characteristic includes: 1 high-frequency full-bridge inverter, LCC-S resonance compensation network, transmitting end and output end DD coil, 2 full-bridge rectifiers, 2 independent external inductors L p1 、 L p2 、 4 independent external capacitors C e1 、 C e2 、 C p1 、 C p2 , 2 load resistors R L3 、 R L4 The input DC voltage of the inverter is U dc , and the operating angular frequency isω , the output fundamental voltage is U .

[0016] As shown in Figure 2 , the DD coil magnetic coupling mechanism is double D type. The double D type coil emitter plate is four coplanar plates, including a first pair of emitter plates T 1, T 2, a second pair of emitter plates T 3, T 4; the double D type coil receiver plate is four coplanar plates, including a first pair of receiver plates R 1, R 2, a second pair of receiver plates R 3, R 4. The transmitting coil is of the type of "outer dense and inner sparse", that is, the outer four coils are densely wound, and the inner four coils are sparsely wound, with a spacing of 2mm between the sparsely wound coil wires; the receiving coil is of the type of "outer sparse and inner dense", that is, the outer four coils are sparsely wound, and the inner four coils are densely wound, with a spacing of 2mm between the sparsely wound coil wires. The two pairs of emitter and receiver plates are arranged in a cross arrangement.

[0017] A double-load automatic guided vehicle wireless charging system with anti-offset characteristic comprises six independent external capacitors C e1 、 C e2 、 C e3 、 C e4 、 C p1 、 C p2 , C e1 and emitter plate T 1, T 2 in series, C p1 and C e1 and emitter plate T 1, T 2 in parallel as input port 1, C e2 and receiver plate R 1, R 2 in series as output port 1; C e2 and emitter plate T 3, T 4 in series, C p2 and C e3 and emitter plate T 3, T4 are connected in parallel as input port 2. C e4 and receiving electrode plate R 3, R 4 are connected in series as output port 2; like Figure 3 As shown, the LCC compensation section of the LCC-S resonant compensation network consists of independent impedance elements. C e1 , C e3 , C p1 , C p2 With transmitting coil T X1 , T X2 Composition, in which C e1 One end is connected to the positive output terminal of the inverter, and the other end is connected to the transmitting coil. T X1 connect; C p1 Parallel connection to the transmitting coil T X1 and C e1 Both ends; transmitting coil T X1 The other end is connected to the negative output terminal of the inverter. C e3 One end is connected to the positive output terminal of the inverter, and the other end is connected to the transmitting coil. T X2 connect; C p2 Parallel connection to the transmitting coil T X2 and C e3 Both ends; transmitting coil T X2 The other end is connected to the negative output terminal of the inverter.

[0018] The LCC-S resonant compensation network has independent impedance elements in the SS compensation section. C e2 One end of it is connected to the receiving coil. R X1 One end is connected to the rectifier, and the other end is connected to the positive potential terminal of the rectifier's input voltage; independent impedance element. C e4 One end of it is connected to the receiving coil. R X2 Connect one end closer to the rectifier, and connect the other end to the positive potential terminal of the rectifier's input voltage.

[0019] The coupled two-sided loop is added with KVL, and the following voltage equation set is established: The overall main loop input impedance expression is obtained: The equivalent impedance of the receiving end is: The output voltage of the receiving end is: Through algebraic elimination and combining the mutual inductance coupling relationship, the overall voltage gain expression is derived as follows: The system effective power is: The efficiency is defined as: To achieve high-efficiency operation of the system, the LCC compensation network needs to meet the following resonance conditions: When the above conditions are met, the system reaches a double-sided resonance state, achieving zero-phase angle input and improving energy transmission efficiency.

[0020] Under the action of the lateral offset Δ x , the coupling coefficient k will decrease, and the mutual inductance M can be expressed as: where k (Δ x ) can be fitted as a Gaussian decay function through simulation: The LCC-S resonant compensation network is configured to: When the inverter output angular frequency ω satisfies: The system enters a double-sided resonance state, achieving zero-phase angle input and constant voltage output.

[0021] Embodiment: Analysis of simulation results A double-D coupling mechanism model is built in finite element simulation software. The transmitting end and the receiving end both adopt the structure of orthogonally arranged D-shaped coils, the outer diameter of the coil is 20 cm x 10 cm, the inner diameter is 15 cm x 5 cm, the number of turns of the winding is 8 turns, and the winding method is Litz wire. In order to improve the anti-offset capability, the transmitting end coil adopts the winding method of "dense outside and sparse inside", the receiving end adopts the winding method of "sparse outside and dense inside", and a ferrite core is added at the bottom to reduce magnetic leakage. The thickness of the coil is 2 mm, and the installation height is 0.05 m. The self-induction and mutual induction of each coil are calculated by finite element software, and the coupling coefficient is further calculated k , it is verified that within the offset range of 20 cm in X and Y directions, the coupling coefficient remains above 0.25, and has good anti-offset performance.

[0022] As shown in Figure 4 , Figure 5 , the double-load automatic guiding vehicle wireless charging system with anti-offset characteristic is built in LCC-S compensation circuit model in circuit simulation software. The system input DC voltage is set to 30V, and the working frequency is 85kHz. The compensation network parameters are designed as: primary compensation inductance L P1 =4.7μH, coil self-induction L 1=30μH, L 2=14μH, series compensation capacitor C e1 =100nF, C e2 =180nF, and parallel compensation capacitor C p1 =538.9nF. L P2 =4.7μH, coil self-induction L 3=30μH, L 4=14μH, series compensation capacitor C e3 =100nF, C e4 =180nF, and parallel compensation capacitor C p2 =538.9nF. As Figure 6 , the simulation results show that when the load range changes from 5 to 60Ω, the output voltage is stabilized at about 14.7V, and the voltage fluctuation is less than 11%, realizing constant voltage output. At the same time, it can be seen from the frequency spectrum analysis that the harmonic content after compensation is significantly reduced, ensuring the high efficiency of the system.

[0023] The efficiency under different loads is tested as follows Figure 7The results show that when the load resistance is in the range of 5 Ω-60 Ω, the system efficiency has a slight downward trend with the change of load, which can be considered as almost unchanged, and the overall efficiency is always maintained above 85%. Combined with the simulation and experimental platform test results, the system can maintain stable operation under multiple load conditions and has good decoupling characteristics. When one of the inputs is disconnected, the voltage and current of the other output port remain basically unchanged, proving that the system has the ability to operate independently in multiple channels.

[0024] It can be seen that the automatic guided vehicle wireless charging system with double-D coil and LCC-S compensation topology can ensure transmission efficiency while improving anti-offset performance and achieving independent stable power supply under multiple loads. This scheme can meet the continuous power supply needs of automatic guided vehicles in complex operating environments and has high application value.

Claims

1. A dual load automatic guided vehicle wireless charging system with anti- drift characteristics, characterized in that, It comprises: 1 high-frequency full-bridge inverter, double-D type orthogonal magnetic coupling mechanism, LCC-S type resonant compensation network, 2 full-bridge rectifiers and load circuit; the system can provide power for two independent loads at the same time, and realize output voltage stability and transmission efficiency optimization under the condition of load change and coupling mechanism offset through the LCC-S compensation network.

2. The dual load automatic guided vehicle wireless charging system with anti-offset characteristic according to claim 1, wherein, The D-shaped coil is formed by two rectangular or semicircular winding pairs which are symmetrically distributed, with an outer diameter of 20 cm, an inner diameter of 10 cm, and a 5 cm installation allowance reserved in the inner diameter part; the transmitting end coil T X1 、 T X2 The coplanar "outer dense inner sparse" winding is adopted: the outer contour is 20 cm*10 cm, the inner opening is 15 cm*5 cm, the first 4 turns are densely wound, the last 4 turns are sparsely wound, the sparse winding interval is 2 mm, the single coil inductance is 18 µH, and the number of turns is 8 turns; the receiving end coil R X1 、 R X2 is symmetrically wound with the transmitting end coil as "outer sparse inner dense", with the same size and a 3 cm installation gap; the transmitting coil is "outer dense inner sparse" and the receiving coil is "outer sparse inner dense" to reduce high-frequency eddy current loss and improve the anti-deviation performance of the system; the back of the coils is attached with a ferrite core to directionally constrain the magnetic force lines, reduce the magnetic leakage and eddy current loss, improve the coupling coefficient, shield the electromagnetic interference of the metal components behind, and enhance the anti-deviation capability and transmission efficiency; Six independent externally connected capacitors C e1 、 C e2 、 C e3 、 C e4 、 C p1 、 C p2 , C e1 with the first pair of emitter plates T 1, T 2 in series, C p1 with C e1 and the first pair of emitter plates T 1, T 2 in parallel as input port 1, C e2 and the first pair of collector plates R 1, R 2 in series as output port 1; C e2 with the second pair of emitter plates T 3, T 4 in series, C p2 with C e3 and the second pair of emitter plates T 3, T 4 in parallel as input port 2, C e4 and the second pair of collector plates R 3, R 4 in series as output port 2; The LCC-S type resonance compensation network comprises a transmitting side LCC compensation unit and a receiving side S compensation unit; the LCC compensation part is composed of independent impedance elements C e1 、 C e3 、 C p1 、 C p2 and a transmitting coil T X1 、 T X2 , wherein C e1 one end is connected with the positive end of the inverter output, and the other end is connected with the transmitting coil T X1 , C p1 is connected in parallel across the transmitting coil T X1 and C e1 , and the other end of the transmitting coil T X1 is connected with the negative end of the inverter output; C e3 one end is connected with the positive end of the inverter output, and the other end is connected with the transmitting coil T X2 , C p2 is connected in parallel across the transmitting coil T X2 and C e3 , and the other end of the transmitting coil T X2 is connected with the negative end of the inverter output; the S-S compensation part is composed of independent impedance elements C e2 , one end of which is connected with the receiving coil R X1 close to the rectifier, and the other end is connected with the positive potential end of the rectifier input voltage, and the independent impedance element C e4 , one end of which is connected with the receiving coil R X2 close to the rectifier, and the other end is connected with the positive potential end of the rectifier input voltage; the LCC-S compensation network needs to satisfy the following resonance conditions: ， ， ； wherein, ω is the angular frequency, L p is the equivalent inductance of the transmitting coil; the LCC-S type resonance compensation network is in parallel form; When the system is offset by ± 20 cm in the X or Y direction, it can still maintain the coupling coefficient k ≥ 0.25, the system transmission efficiency is not less than 65%, and the output voltage change rate is not more than 11%, showing good anti-offset performance and output stability; The high-frequency full-bridge inverter converts 30 V DC input into 85 kHz high-frequency AC power; the full-bridge rectifier converts high-frequency AC power into DC power to supply power to the load; the system has the ability to work with multiple loads at the same time, and can realize power self-balancing; the system also integrates impedance analysis module, voltage and current sensing unit and DSP-based digital controller for system state monitoring, resonant frequency tracking and adaptive energy management.

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