CN115441593B - Double-solenoid type coupling mechanism and parameter design method thereof - Google Patents

Double-solenoid type coupling mechanism and parameter design method thereof Download PDF

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CN115441593B
CN115441593B CN202210850859.6A CN202210850859A CN115441593B CN 115441593 B CN115441593 B CN 115441593B CN 202210850859 A CN202210850859 A CN 202210850859A CN 115441593 B CN115441593 B CN 115441593B
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coil
solenoid
coupling mechanism
magnetic core
guide rail
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CN115441593A (en
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吴晓锐
孙跃
李小飞
肖静
陈绍南
左月
周远钊
韩帅
莫宇鸿
吴宁
龚文兰
陈卫东
郭敏
郭小璇
唐春森
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Chongqing University
Electric Power Research Institute of Guangxi Power Grid Co Ltd
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Electric Power Research Institute of Guangxi Power Grid Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
    • H02J50/005—Mechanical details of housing or structure aiming to accommodate the power transfer means, e.g. mechanical integration of coils, antennas or transducers into emitting or receiving devices
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L53/00—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles
    • B60L53/10—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles characterised by the energy transfer between the charging station and the vehicle
    • B60L53/12—Inductive energy transfer
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/24—Magnetic cores
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/28—Coils; Windings; Conductive connections
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F38/00—Adaptations of transformers or inductances for specific applications or functions
    • H01F38/14—Inductive couplings
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
    • H02J50/10—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
    • H02J50/10—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling
    • H02J50/12—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling of the resonant type

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Theoretical Computer Science (AREA)
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  • Evolutionary Computation (AREA)
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  • General Engineering & Computer Science (AREA)
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Abstract

The invention relates to the technical field of wireless electric energy transmission, and particularly discloses a double-solenoid type coupling mechanism and a parameter design method thereof. The invention ensures that the transmission power of the system has good stability when the large-range offset occurs, and improves the anti-offset capability of the system. The transverse anti-offset capability of the magnetic coupling mechanism can be exerted to a higher level by matching with a corresponding parameter design method. Further, when the multi-section double-solenoid type transmitting guide rail is applied to dynamic wireless charging, no obvious power drop exists in the guide rail switching domain.

Description

Double-solenoid type coupling mechanism and parameter design method thereof
Technical Field
The invention relates to the technical field of wireless power transmission, in particular to a double-solenoid type coupling mechanism and a parameter design method thereof.
Background
The wireless power transmission (Wireless Power Transfer, WPT) technology can complete the contactless power transmission between the power utilization device and the power supply facility without depending on a physical carrier such as a plug, a wire and the like, thereby greatly increasing the safety and reliability of the power transmission. The wireless power transmission has various transmission modes, and can be roughly classified into a microwave mode, a laser mode, a magnetic field coupling mode, an electric field coupling mode and the like, wherein the wireless power transmission (Magnetic Coupling Wireless Power Transfer, MC-WPT) technology based on magnetic field coupling is the most mature technology in the WPT field research and the most widely applied technology, and has the advantages of simple system structure, long transmission distance, high transmission power and efficiency and the like. The WPT technology is one of ten emerging technologies with the greatest influence on the world, provides an optimal solution for technical bottlenecks of a plurality of industries, provides a new solution for global energy challenges, and further promotes the rapid development of related industries.
The traditional electric energy supply mode of the electric automobile (Electrical Vehicle, EV) adopts a wired charging mode, the charging process is completed under the cooperation of people, and meanwhile, the unavoidable system circuit is aged, short-circuit risks exist during charging in rainy days, and the like, so that the safety and reliability of equipment power supply are greatly reduced. The MC-WPT technology can well solve the problems, and has been widely studied and applied in recent years. When the MC-WPT technology is applied to the field of electric automobiles, the MC-WPT technology can be mainly divided into two modes of static wireless power transmission and dynamic wireless power transmission, wherein the static wireless power transmission (Electrical Vehicle Stationary Wireless Power Transfer, EV-SWPT) refers to the electric power supply of the electric automobile when the electric automobile is parked in a parking space or a special parking station, and the electric automobile is relatively stationary in the whole charging process; the dynamic wireless power transmission (Electrical Vehicle Dynamic Wireless Power Transfer, EV-DWPT) of the electric automobile is used for wirelessly charging the electric automobile in the running process of the electric automobile, and the electric automobile does not need to carry a large-capacity energy storage battery in the mode, so that the whole automobile space is saved, and the weight and the cost of the automobile can be reduced.
The power supply rail of the EV-DWPT system has two modes of long rail power supply and distributed short rail power supply. The long guide rail mode system is generally composed of a set of primary side electric energy conversion device, a long guide rail, an energy receiving coil and a secondary side electric energy conversion device, and has simple structure and control strategy and lower engineering construction cost. However, the length of the guide rail is generally tens of meters, the equivalent series impedance (Equal Series Resistance, ESR) of the guide rail is large, and meanwhile, a large magnetic leakage condition exists on a road section where no vehicle runs, so that on one hand, the coupling coefficient and the transmission efficiency of the system are reduced, and on the other hand, serious electromagnetic pollution is caused, and the health of people, animals and plants on the road is endangered. In practical engineering application, an EV-DWPT system usually adopts a distributed short rail power supply mode, unlike a long rail power supply mode, a primary side of the system is composed of multiple sets of primary side power conversion devices and multiple sections of distributed short rails, the working state of each section of rail is controlled by a set of independent power conversion devices, and when a vehicle runs above a certain section of rail, a corresponding section or multiple sections of short rails are started to work, and other rails are in a dormant or standby state. The coupling coefficient and the system transmission efficiency of the distributed short guide rail power supply mode are high, electromagnetic radiation is small, but engineering construction cost is high, and in addition, the switching control method of the distributed short guide rail is relatively more complex. More importantly, the distributed short guide rail has serious mutual inductance drop in a guide rail switching domain, so that the drop of transmission power is caused, the efficient and reliable electric energy supply of the electric automobile in the running process is not facilitated, and the service life of the vehicle-mounted battery is seriously influenced.
Related scholars and teams at home and abroad conduct a great deal of research on dynamic wireless power supply of electric vehicles with distributed short guide rails, but the following problems still exist: firstly, the additional detection circuit and control circuit increase the complexity of the system; secondly, the control requirement of the EV-DWPT system in high-speed motion is difficult to meet by a complex control strategy; thirdly, the multi-channel EV-DWPT system can cross-couple when laterally offset, resulting in system detuning and failure to work properly.
Disclosure of Invention
The invention provides a double-solenoid type coupling mechanism and a parameter design method thereof, which solve the technical problems that: how to design a magnetic coupling mechanism with stronger anti-offset capability.
In order to solve the technical problems, the invention provides a double-solenoid type coupling mechanism, which comprises a transmitting structure and a receiving structure, wherein the transmitting structure comprises a double-solenoid type transmitting guide rail, the double-solenoid type transmitting guide rail comprises a square tubular magnetic core perpendicular to a road surface, and an inner energy transmitting solenoid and an outer energy transmitting solenoid which are respectively spirally wound on the inner wall and the outer wall of the square tubular magnetic core, wherein the inner energy transmitting solenoid and the outer energy transmitting solenoid are wound by the same litz wire but are wound in opposite directions;
The receiving structure comprises pickup coils, receiving end magnetic cores and metal shielding plates which are arranged in a hierarchical mode, and the pickup coils are of square annular structures.
Preferably, the square tubular magnetic core comprises an inner square tubular magnetic core, a middle square tubular magnetic core and an outer square tubular magnetic core which are separated, the inner energy emission solenoid is wound on the inner wall of the inner square tubular magnetic core, and the outer energy emission solenoid is wound on the outer wall of the outer square tubular magnetic core.
Preferably, a square protrusion is arranged at the center of the receiving end magnetic core, and the square protrusion is embedded in a square gap at the center of the pick-up coil.
Preferably, the double-solenoid type emission guide rail is provided with a plurality of emission guide rails which are equidistantly distributed along the road direction.
Preferably, the inner energy emitting solenoid, the outer energy emitting solenoid emitting coil and the pick-up coil are wound by litz wire with the specification of 0.1mm by 1000 strands and the outer diameter of 5 mm.
Preferably, the square tubular magnetic core and the receiving end magnetic core are made of manganese-zinc ferrite made of PC95 material.
The invention also provides a parameter design method of the double-solenoid type coupling mechanism, which records the number of turns of the external energy emitting solenoid as n 1 The number of turns of the pick-up coil is n 2 N is determined by the following steps 1 、n 2 ：
A1, target mutual inductance value M of given design min A transmission distance h;
a2, combining the outer squareSizing of the tubular core and the receiving end core, n 1 Maximum value (n) 1 ) max 、n 2 Maximum value (n) 2 ) max ；
A3, let n 1 ＝n 2 =1, calculating the mutual inductance M of the magnetic coupling mechanism by means of COMSOL finite element simulation software;
a4, judging whether M is larger than M min If yes, recording the current n 1 、n 2 If not, entering the next step;
A5、n 2 adding 1, i.e. n 2 ＝n 2 +1；
A6, judging the current n 2 Whether or not it is greater than (n) 2 ) max If not, returning to the step A4, and if yes, entering the next step;
a7, let n 2 ＝1，n 1 Adding 1, i.e. n 1 ＝n 1 +1；
A8, judging the current n 1 Whether or not it is greater than (n) 1 ) max If not, returning to the step A4, if yes, the design fails.
Further, after n is determined 1 、n 2 The coil size of the internal energy emitting solenoid is then determined by:
b1, combining the power level of the system, and giving the number of turns of the coil in the transmitting guide rail and the maximum drop delta M of mutual inductance during deflection max Giving an initial value of the coil size;
b2, simulating the anti-offset characteristic of the system;
b3, analyzing whether the drop delta M of mutual inductance in the offset is smaller than delta M max If yes, recording the current coil size, otherwise, adjusting the coil size and returning to the step B2.
The invention provides a magnetic coupling mechanism with a double-solenoid structure and a parameter design method thereof, wherein a transmitting mechanism adopts a double-solenoid type transmitting guide rail, and comprises an internal energy transmitting solenoid and an external energy transmitting solenoid which are spirally wound on the inner wall and the outer wall of a square tubular magnetic core. The transverse anti-offset capability of the magnetic coupling mechanism can be exerted to a higher level by matching with a corresponding parameter design method. Further, when the multi-section double-solenoid type transmitting guide rail is applied to dynamic wireless charging, no obvious power drop exists in a guide rail switching domain, and the stability of output power in the dynamic charging process is realized.
Drawings
FIG. 1 is a schematic diagram of a transmitting EV-DWPT system provided by an embodiment of the present invention;
fig. 2 is a topology diagram of a voltage type full-bridge inverter according to an embodiment of the present invention;
FIG. 3 is a circuit topology of a T-type resonant compensation network provided by an embodiment of the present invention;
FIG. 4 is a diagram of a mutual inductance model of a magnetic coupling mechanism of a single-emission EV-DWPT system provided by an embodiment of the invention;
FIG. 5 is a diagram of a decoupling equivalent circuit of a magnetic coupling mechanism provided by an embodiment of the present invention;
FIG. 6 is an overall block diagram of a distributed short-rail EV-DWPT system provided by an embodiment of the present invention;
FIG. 7 is a logic diagram of rail switch timing provided by an embodiment of the present invention;
FIG. 8 is a schematic diagram of a planar rectangular magnetic coupling mechanism provided by an embodiment of the present invention;
FIG. 9 is a schematic diagram of a rectangular coordinate system of a coil of a dual-emission magnetic coupling mechanism according to an embodiment of the present invention;
FIG. 10 is a graph of system mutual inductance fluctuation trend provided by an embodiment of the present invention;
FIG. 11 is a schematic diagram of a dual solenoid magnetic coupling mechanism provided by an embodiment of the present invention;
FIG. 12 is a block diagram of a planar rectangular magnetic coupling mechanism provided by an embodiment of the present invention;
FIG. 13 is a cloud image of the magnetic field distribution of a planar rectangular magnetic coupling mechanism provided by an embodiment of the present invention;
FIG. 14 is a magnetic field distribution cloud for a dual solenoid coupling mechanism provided by an embodiment of the present invention;
FIG. 15 is a diagram showing the mutual inductance change of two coupling mechanisms according to an embodiment of the present invention;
FIG. 16 is a layout of a self-coupling region and a cross-coupling region in a y-z profile provided by an embodiment of the present invention;
FIG. 17 is a diagram of a y-z section equivalent magnetic circuit model provided by an embodiment of the present invention;
FIG. 18 is a flow chart of design optimization of a magnetic core structure provided by an embodiment of the present invention;
FIG. 19 is a diagram of a magnetic coupling mechanism after magnetic core optimization according to an embodiment of the present invention;
FIG. 20 is a graph showing the coupling coefficient of two magnetic core structures according to an embodiment of the present invention;
FIG. 21 is a flow chart of a coil optimization design provided by an embodiment of the present invention;
FIG. 22 is a graph of mutual inductance versus number of turns provided by an embodiment of the present invention;
FIG. 23 is a graph of coupling coefficient versus number of turns for a coil provided by an embodiment of the present invention;
fig. 24 is a graph of mutual inductance variation trend under different widths L provided by the embodiment of the present invention;
FIG. 25 is a three-dimensional plot of mutual inductance of two magnetic coupling mechanisms provided by an embodiment of the present invention.
Detailed Description
The following examples are given for the purpose of illustration only and are not to be construed as limiting the invention, including the drawings for reference and description only, and are not to be construed as limiting the scope of the invention as many variations thereof are possible without departing from the spirit and scope of the invention.
This embodiment will be described by taking an EV-DWPT system as an example.
The EV-DWPT system mainly comprises an AC/DC converter, a DC/DC converter, a high-frequency inverter, a resonance compensation network, a magnetic coupling mechanism, a rectifying and filtering circuit and the like, as shown in figure 1. The power frequency alternating current of the power grid is sent to a high-frequency inverter after rectification and filtering of an AC/DC converter and boost conversion of the DC/DC converter, high-frequency inversion voltage with specific frequency is generated, the high-frequency inversion voltage acts on a resonance compensation network and a transmitting guide rail to generate a high-frequency alternating magnetic field with the same frequency, an energy pickup coil is placed in the high-frequency alternating magnetic field to generate high-frequency induction current, and the high-frequency induction current is converted into direct-current voltage and current required by charging an electric automobile through a series of electric energy conversion links such as resonance compensation and rectification and filtering, so that the electric automobile vehicle-mounted battery pack is charged, and wireless transmission of electric energy is realized. The invention adopts the direct current power supply as the input of the high-frequency inverter, omits the AC/DC converter and the DC/DC converter, and simplifies the system model. Several key elements of the high-frequency inverter, the resonance compensation network, the magnetic coupling mechanism, and the like will be described below.
The EV-DWPT system based on the magnetic coupling resonance mode has the advantages of high system power density, long energy transmission distance, high overall efficiency and the like. In order to make the EV-DWPT system in a resonance state, the power factor of the system is improved, the self inductance of the coupling coil is generally compensated by adopting a series-parallel capacitance mode, and the value of the compensation capacitance can be determined by a formula (0.1).
ω 2 LC＝1(0.1)
In order to reduce the volume of the resonant element, the value of the compensation capacitor should be as small as possible under the premise of ensuring the system resonance. As can be seen from the formula (0.1), the higher the system working frequency is, the smaller the value of the compensation capacitor C is when the resonance state is reached under the same condition, so that the energy transmission level and the power density of the system can be improved by increasing the system working frequency, and therefore, the high-frequency inverter circuit is important for the EV-DWPT system.
The circuit topology of the high-frequency inverter circuit has various forms, wherein the voltage type full-bridge inverter circuit overcomes the defects of a half-bridge type inverter circuit and a push-pull type inverter circuit, and has the advantages of simple structure, high output capacity, high power density, high transmission efficiency, simple control strategy and the like, so that the EV-DWPT system designed in the invention adopts the voltage type full-bridge inverter circuit in consideration of the aspects of the circuit complexity, the input-output voltage level, the power capacity requirement and the like of the EV-DWPT system, as shown in figure 2. The voltage type full-bridge high-frequency inverter circuit consists of a voltage stabilizing capacitor and four switching tubes which are connected in parallel, wherein the two switching tubes are combined into a bridge structure of the inverter circuit, and S is as follows 1 、S 3 Form a oneGroup bridge arm S 2 、S 4 And the other group of bridge arms is formed, and the switching tubes on the same bridge arm are alternately and complementarily conducted, so that the occurrence of system short circuit is avoided. The switching tube usually adopts a MOSFET with high switching speed, small conduction loss and high power level, and the switching tube is controlled to be conducted and cut off in frequency by a driving signal, so that the conversion from direct current to high-frequency alternating current is realized.
In the EV-DWPT system, a large air gap exists between the transmitting guide rail of the magnetic coupling mechanism and the pick-up coil, the system is in a loose coupling state and the transmitting guide rail is inductive, so that a resonance compensation link is required to be added. The resonance compensation network is an important ring formed by the wireless power transmission system, and the characteristics of the resonance compensation network have important influence on the overall performance of the system. The resonance compensation network in the system is generally composed of compensation inductance and capacitance, and mainly has the following basic roles: (1) forming a system resonant circuit, reducing the equivalent impedance of the system, and generating a magnetic field with high frequency variation; (2) compensating the self-inductance of the transmitting guide rail, reducing the reactive power of the system, and improving the power factor of the system, the grade and the efficiency of power transmission; (3) and higher harmonic waves in the inversion voltage are filtered, so that soft switching is realized, and electromagnetic interference of a system is reduced. The most basic resonance compensation topology of the WPT system has two types of series compensation (S) and parallel compensation (P), and four basic compensation structures can be obtained through different combinations of the two compensation types at two ends of the transmitting guide rail and the pickup coil: the resonance conditions and output characteristics of the four resonance compensation networks are shown in table 1, and the resonance conditions are series-series (SS), parallel-series (PS), series-parallel (SP), parallel-parallel (PP).
Table 1 resonance conditions and output characteristics of four basic compensation structures
Figure BDA0003754593030000071
As can be seen from table 1, the compensation capacitance C of the SS topology among the four compensation topologies s With ω and L only p Compensation capacitor C of PS, SP, PP topology s Except for ω and L p In addition to M, L s R is as follows L Related to the following. In EV-DWPT systemIn a conventional application, the energy pick-up coil located at the bottom of the vehicle is offset (i.e., changes in relative position) from the single firing rail, so the mutual inductance M changes with the vehicle position. The capacitance values of the SP, PP and PS topological resonance states can change along with the change of M, so that the EV-DWPT system can be in a detuned state in the running process of the vehicle, the energy efficiency characteristic of the system is greatly reduced, and the PS, SP and PP topologies are not suitable for the EV-DWPT system. In addition, the secondary side impedance change of the SS topology has a remarkable influence on the primary side current, and the primary side short circuit can be caused under the no-load condition to damage an inverter and other devices, so that the SS structure is not suitable for an EV-DWPT system.
The resonance compensation network has composite compensation networks such as LCL, LCC and the like besides the four basic compensation structures. LCC is the optimization form of LCL compensation network, through increasing a compensation capacitor and make the parameter design of compensation network more nimble, have more extensive application scenario. The LCC resonance compensation network is analyzed by adopting a T-shaped network, and the equivalent circuit topology is shown in figure 3.
The left bridge arm and the right bridge arm of the T-shaped network are inductive, the impedance is jX, the lower bridge arm perpendicular to the two inductive bridge arms is capacitive, the impedance is-jX, and the left bridge arm, the right bridge arm and the lower bridge arm are in a resonance state. If the impedance of the load is known as Z o Equivalent impedance Z of T-network i The method comprises the following steps:
Figure BDA0003754593030000081
when the input is known as U i When it is flowing through the resistor Z o Is the current I of (2) o The method comprises the following steps:
Figure BDA0003754593030000082
as can be seen from the formula (0.3), when the LCC resonance compensation topology is used for primary resonance compensation, the current of the transmitting guide rail is only equal to the input voltage U i Is related to compensating inductance, is independent of mutual inductance M, has constant current characteristic, and can not be subjected to secondary side pickup coilThe influence of the guide rail is ensured, the system has good stability, and the guide rail is suitable for an EV-DWPT system with frequent switching control of the guide rail. When the LCC resonance compensation topology is used for secondary resonance compensation, the system output also has constant current characteristics, and the adjustment of output power can be realized by matching with a vehicle-mounted battery management system (Battery management system, BMS). The EV-DWPT system designed herein employs an LCC-LCC resonance compensation topology.
The electromagnetic coupling mechanism is a core component of the EV-DWPT system, and the shape structure, the winding mode and the energy efficiency characteristic are important contents of research and design. The mutual inductance equivalent model of the single-emission EV-DWPT system is shown in FIG. 4, wherein u 1 For transmitting the input voltage of the rail, i p For transmitting the coil current of the guide rail, u 2 I is the output voltage of the energy pick-up coil s To pick up the induced current of the coil, L p 、L s Self-inductance of the firing rail and the energy pick-up coil, respectively.
The transmitting guide rail generates a high-frequency alternating magnetic field under the action of high-frequency inversion voltage, and the energy pickup coil is placed in the high-frequency alternating magnetic field to generate induced electromotive force u s At the same time, induced electromotive force u is also generated in the primary side emission guide rail p The decoupling equivalent circuit of the electromagnetic coupling mechanism is shown in FIG. 5, in which the self inductance and resistance value of the transmitting rail are L p 、R p L is used for representing self inductance and resistance value of energy receiving coil s 、R s R represents the equivalent load L And (3) representing.
Induced electromotive force u of primary side emission guide rail p The method comprises the following steps:
u p ＝jωMi s (0.4)
induced electromotive force u of energy pickup line s The method comprises the following steps:
u s ＝jωMi p (0.5)
according to kirchhoff's law, the equivalent circuit by the magnetic coupling mechanism can be represented by the following set of equations:
Figure BDA0003754593030000091
let the input impedance of the energy pick-up end be Z s Then:
Figure BDA0003754593030000092
equivalent reflection impedance Z from the energy pick-up end to the primary-side emission guide rail r The method comprises the following steps:
Figure BDA0003754593030000093
therefore, the transmission power P of the electromagnetic coupling mechanism of the EV-DWPT system is as follows:
Figure BDA0003754593030000094
as can be seen from the formula (0.9), the transmission power of the electromagnetic coupling mechanism, the angular frequency omega of the system operation, the mutual inductance M and the primary side emission guide rail current i p Internal resistance R of energy receiving coil s Self-inductance L of energy receiving coil s Equivalent load R L Related to the following. Wherein the angular frequency omega of system operation affects the system tuning, L s 、R s I is determined by the factors such as the structure of the pick-up coil and the number of turns of the winding p The system loss is increased when the line diameter is not too large and is increased, and the equivalent load R L Depending on the equivalent internal resistance of the vehicle-mounted battery, the optimal method for improving the power transmission level of the electromagnetic coupling mechanism is to increase the mutual inductance M. In addition, the angular frequency omega of the system and the internal resistance R of the coil during the running of the electric automobile s Coil self-inductance L s Equivalent load R L The current i of the transmitting guide rail is kept unchanged p From the formula (0.3), it is known that there is a constant current characteristic, and thus the stability of the transmission power of the EV-DWPT system depends on whether the mutual inductance M is stable or not.
The EV-DWPT system based on the distributed short guide rail adopts a multi-transmission parallel structure, and in order to reduce the system construction cost and the number of inverters, the design adopts a mode that two groups of resonance compensation networks and guide rails are driven by the same inverter, and the overall structure of the EV-DWPT system is shown in figure 6. It should be noted that, due to the limitation of the highest operating frequency of the electronic switching device, the switching speed of the guide rail can only reach the order of μs, and a certain response time is required for detecting the position of the vehicle and for controlling the switching of the guide rail, so the length of the transmitting guide rail should be much longer than the length of the pickup coil.
From the foregoing analysis, it is clear that the output power of the system is closely related to the mutual inductance M. In order to obtain stable mutual inductance M, ensure that the electric automobile continuously and stably picks up electric energy in the running process, simultaneously reduce the overall loss of the system and reduce electromagnetic radiation, the guide rail state must be controlled in a segmented time-sharing and switching mode according to the position of a pick-up coil, namely, one or a few groups of guide rails positioned below the electric automobile at a certain moment are ensured to be in an open state, and the rest guide rails are in a standby state. The specific switching control sequence is shown in fig. 7:
the region immediately above the rails is defined herein as the rail center region, and the transition region between the rails is defined as the rail switch region. The working mode of the guide rail switching can be divided into the following 4 stages according to time:
stage 1: the electric automobile is positioned in an nth section of guide rail charging area at the current moment, an inverter with the number of n controls a corresponding guide rail to start to work, the rest guide rails stand by, and a pick-up coil is powered by a transmitting guide rail n;
stage 2: the electric automobile is about to enter a (n+1) -th guide rail charging area, an inverter numbered as (n+1) receives a vehicle position detection signal to start operation, a pick-up coil is still positioned in the area where the emission guide rail n is positioned, and the emission guide rail n supplies electric energy;
Stage 3: at the moment, the magnetic field of the guide rail (n+1) is completely established, the electric automobile runs to a switching area of the guide rail n and the guide rail (n+1), and the pick-up coil is supplied with electric energy by the emission guide rail n and the emission guide rail (n+1);
stage 4: the electric automobile drives out of the guide rail n, at the moment, the inverter with the number n receives a vehicle driving-out signal, the corresponding guide rail state is switched to standby, and the pick-up coil is powered by the transmitting guide rail (n+1).
Similarly, the corresponding transmitting guide rail is controlled to be opened and closed according to the real-time position of the electric automobile, a magnetic field is established before the automobile enters the next transmitting guide rail, the stability of the mutual inductance M is maintained to the maximum extent, the electric energy is continuously and stably picked up by the electric automobile in the driving process, the influence of electromagnetic radiation on the surrounding environment is reduced, and the overall efficiency of the system is improved.
According to the analysis, the sectional time-sharing switching control is performed on the state of the transmitting guide rail, so that the condition that the pick-up coil is positioned in the guide rail switching domain and simultaneously provides energy by the adjacent multi-section transmitting guide rail can be ensured, and the stability of power transmission of the system is improved to a certain extent. It is found that when the relative positions of the energy pickup coil and the transmitting guide rail are changed, the rectangular coil is more stable in mutual inductance than the circular coil structure, and the transmission power of the system is more stable, namely, the magnetic coupling mechanism of the rectangular-rectangular structure has more advantages in output stability, so that the coil of the magnetic coupling mechanism of the EV-DWPT system adopts a planar rectangular structure generally, as shown in fig. 8.
Because the length of the transmitting guide rail is far longer than that of the energy pick-up coil, the pick-up coil is coupled with the two transmitting guide rails at most in the running process of the electric automobile, so that the mutual inductance change rule of the pick-up coil at different positions of the guide rails is studied by taking the double-transmitting magnetic coupling mechanism as a minimum unit, and a rectangular coordinate system of the coil of the double-transmitting EV-DWPT system magnetic coupling mechanism is established as shown in figure 9.
Assuming that the length L, width W and number of turns N of the coil are the outermost coil of the transmitting guide rail 1 The method comprises the steps of carrying out a first treatment on the surface of the The length of the outermost coil of the pick-up coil is l, the width is w, and the number of turns of the coil is N 2 The turn-to-turn distance of each coil is d. A space rectangular coordinate system is established by taking the middle position of the two transmitting guide rails (namely the center of the guide rail switching domain) as an original point O, and the center coordinate of the pick-up coil is assumed to be O' at the moment, the i < th > (i=1, 2, …, N) of the transmitting guide rail 1 from outside to inside 1 ) The apexes of the turn coils are respectively A i 、B i 、C i 、D i The emission guide rail 2 is i (i=1, 2, …, N 1 ) The apexes of the turn coils are E respectively i 、F i 、G i 、H i The pick-up coil is at the j (j=1, 2, …, N from outside to inside 2 ) Turn wireThe apexes of the circles are respectively a i 、b i 、c i 、d i The coordinates of the various vertices of the launching rail 1 can then be listed as:
Figure BDA0003754593030000111
similarly, the coordinates of each vertex of the launching guide rail 2 are:
Figure BDA0003754593030000121
assuming that the coordinates of the center position of the pick-up coil are O' (x, y, z), a i 、b i 、c i 、d i Can be expressed as:
Figure BDA0003754593030000122
knowing the coordinates of the respective vertices in formulas (0.10), (0.11), the ith turn loops of launching track 1 and launching track 2, respectively, can be denoted as l p1 (i)、l p2 (i)：
Figure BDA0003754593030000123
Figure BDA0003754593030000124
Knowing the coordinates of each vertex in (0.12), pick up the jth turn loop of the coil s (j) Can be expressed as:
Figure BDA0003754593030000125
according to the Nofmann mutual inductance calculation formula, the ith turn loop l of the transmitting guide rail 1 and the transmitting guide rail 2 p1 (i)、l p2 (i) Loop l with the j-th turn of the pick-up coil s (j) The mutual inductance between the two is as follows:
Figure BDA0003754593030000126
Figure BDA0003754593030000127
mu in the middle 0 ＝4π×10 -7 N/A 2 Is vacuum permeability, mu r Is of relative permeability, R ij Loop i of the ith turn of the launching rail p1 (i)、l p2 (i) Loop l with the j-th turn of the pick-up coil s (j) Is a infinitesimal distance of (a). The mutual inductance of the launching rail 1 and the launching rail 2 with the pick-up coil can be expressed as:
Figure BDA0003754593030000128
Figure BDA0003754593030000131
the total mutual inductance M of the magnetic coupling mechanism of the dual-emission EV-DWPT system can be expressed as:
M＝M 1 +M 2 (0.20)
taking the length of the transmitting guide rail as 0.6m, the width as 0.25m, the number of turns as 8 turns, the length as 0.3m, the width as 0.3m, the number of turns as 15 turns and the coupling distance as 0.1m as an example, the system mutual inductance characteristic of the planar rectangular magnetic coupling mechanism is studied, and the mutual inductance change rule between the energy pickup coil and the primary side transmitting guide rail in the running process of the electric automobile is mainly considered. Defining the running direction of the electric automobile as the x direction, the transverse offset direction as the y direction, and feeding high-frequency alternating currents with the same frequency, the same phase and the same amplitude into the two energy emission guide rails at the same moment, so that the energy pickup coil moves from the center opposite position (x= -0.325) of one emission guide rail to the center opposite position (x=0.325) of the next emission guide rail along the x direction, and the energy pickup coil can be calculated To obtain mutual inductance M between the different position transmitting guide rails 1, 2 and the energy pick-up coils 1 、M 2 And the sum M of the mutual inductance between the two transmitting guide rails and the energy pickup coil, and drawing the mutual inductance M 1 、M 2 And M as the energy pick-up coil moves in the x-direction as shown in FIG. 10 (a) (where the line starting point is M highest 1 )。
As can be seen from fig. 10 (a), the mutual inductance M is generated during the movement of the energy pick-up coil from the center of the transmitting rail 1 to the center of the transmitting rail 2 when the coupling distance is fixed 1 Gradually decrease, mutual inductance M 2 Gradually increasing, and the mutual inductance M shows a trend of decreasing before increasing, is largest when being positioned above the center of the transmitting guide rail, is smallest when being positioned in the switching domain of the transmitting guide rail, and is symmetrically distributed by taking the switching domain of the guide rail as the axial center, and the result shows that the mutual inductance of the system in the switching domain of the guide rail is obviously dropped. In addition, during actual running of the electric vehicle, lateral offset is unavoidable due to environmental and human factors, and a fitted curve of the mutual inductance M when the pickup coil is laterally offset above the center of the transmitting rail is drawn by calculation is shown in (b) of fig. 10. As can be seen from the figure, the mutual inductance M gradually decreases as the pick-up coil is shifted from side to side, and the mutual inductance M of the magnetic coupling mechanism is greatest at the center of the transmitting rail facing position.
Therefore, the planar rectangular magnetic coupling mechanism can obviously fluctuate in mutual inductance when the relative positions of the energy pickup coil and the transmitting guide rail change, and particularly can greatly fall off when the guide rail is switched over and large-range transverse offset occurs. It should be noted that, in order to enhance the mutual inductance, a ferrite core is usually added in the magnetic coupling mechanism, and the mutual inductance change rule of the system after the addition of the ferrite core is consistent with the analysis, and serious mutual inductance drop occurs in the guide rail switching area and when a large offset occurs. In summary, the mutual inductance fluctuation of the EV-DWPT system in the dynamic operation process causes the fluctuation of the output power of the system. The magnitude of the mutual inductance depends on the geometry, the size, the number of turns, the coupling distance of the electromagnetic coupling mechanism and the magnetic field distribution around the pick-up coil under the action of the magnetic core, in order to maintain the stability of the mutual inductance in the dynamic operation process of the system and improve the stability of the output power in the dynamic operation process of the EV-DWPT system, a magnetic coupling mechanism with a double-solenoid structure is provided, and a schematic diagram of the magnetic coupling mechanism is shown in fig. 11. The magnetic coupling mechanism comprises a transmitting structure and a receiving structure, wherein the transmitting structure comprises a plurality of double-solenoid type transmitting guide rails which are equidistantly distributed along the road direction, each double-solenoid type transmitting guide rail comprises a square tubular magnetic core which is perpendicular to the road surface, and an inner energy transmitting solenoid (an energy transmitting solenoid 2) and an outer energy transmitting solenoid (an energy transmitting solenoid 1) which are respectively wound on the inner wall and the outer wall of the square tubular magnetic core in a spiral mode, wherein the inner energy transmitting solenoid and the outer energy transmitting solenoid are wound by the same litz wire but are wound in opposite directions. The receiving structure comprises a (energy) picking coil, a receiving end magnetic core and a metal shielding plate (aluminum plate) which are arranged in a level mode, and the picking coil is of a square annular structure.
For a magnetic field coupling wireless power transmission system, the higher the working frequency is in a certain range, the higher the power transmission level and efficiency of the magnetic coupling mechanism are, but the higher the system loss caused by skin effect and proximity effect generated by a high-frequency alternating magnetic field is, and the insulating layer of the wire is melted due to heating of the wire in severe cases, so that the risks of ignition, short circuit, fire and the like are caused. The magnitude of the skin effect is expressed in terms of skin depth δ, namely:
Figure BDA0003754593030000141
wherein ρ represents the resistivity of the conductor, and the size thereof is 1.72X10 at normal temperature -8 Omega.m; f represents the frequency of the current flowing through the coil in Hz; mu (mu) o Is vacuum permeability, the value is 4pi×10 -7 H/m；μ r The relative permeability of the copper wire is 1. As can be seen from the formula (0.21), as the frequency increases, the skin depth δ becomes smaller, the skin effect becomes stronger, and the skin depth values of copper at different frequencies are given in table 2.
TABLE 2 skin depth values for copper at different frequencies
Figure BDA0003754593030000142
Figure BDA0003754593030000151
Wireless power transmission systems typically operate at high frequencies, and in order to reduce the negative effects of skin effects on the system, the magnetic coupling mechanism must use litz wire as the coil material. The EV-DWPT system designed by the method adopts the working frequency of 85kHz, and combines the specification of the litz wire commonly used in the market to decide to select litz wire with single strand wire diameter of 0.1mm as coil material. In addition, the rated current value of the litz wire is also an important parameter for selection, and the corresponding relation between different specifications of the litz wire and the current resistance value of the litz wire is given in the following table 3. Considering the current-resistant capability of the litz wire comprehensively, the transmitting coil and the pickup coil are wound by litz wire with the specification of 0.1mm by 1000 strands and the outer diameter of 5 mm.
TABLE 3 litz wire selection reference Specification Table
Figure BDA0003754593030000152
In order to increase the coupling coefficient of the system and reduce the magnetic leakage of the coupling mechanism, it is generally necessary to add a magnetic core to the magnetic coupling mechanism. The ferrite core is mainly divided into two materials of manganese-zinc base and nickel-zinc base, the magnetic permeability and saturation magnetic flux density of the manganese-zinc base ferrite are high, the core loss is low when the frequency is less than 1MHz, and the ferrite core is more suitable for the wireless power transmission system than the nickel-zinc base ferrite. The Mn-Zn-based ferrite core applied to high-power occasions mainly comprises PE22, PC40, PC95 and other types, the material characteristics of the three types of cores are listed in the table 4, parameters such as core loss, magnetic permeability and saturation magnetic flux density are comprehensively considered, and the Mn-Zn ferrite made of the PC95 material is selected as a core material in the design.
Table 4 material properties of three types of cores
Figure BDA0003754593030000153
In EV-DWPT systems, the magnetic coupling mechanism often adopts a planar rectangular structure, as shown in FIG. 12. The structure has the advantages of high coupling coefficient, long transmission distance and the like, but the analysis of the previous chapter proves that the transmission power of the pick-up coil can be obviously dropped when the guide rail is switched to a domain and is transversely shifted.
In order to realize the stability of the output power of the electric automobile in the guide rail switching domain and improve the anti-offset capability of the system, the structure of the magnetic coupling mechanism is optimally designed. Since the energy pickup coil of the EV-DWPT system is usually mounted at the bottom of the automobile, its size and weight are severely limited, and particularly the thickness of the energy pickup coil should be as thin as possible, the energy pickup coil still adopts a planar rectangular structure, and the focus of the study herein is on the transmitting-end rail structure.
The dual solenoid type firing end rail structure proposed herein is shown in fig. 13. The structure is different from the coil structure of a planar rectangular transmitting guide rail, and is similar to a solenoid winding mode, the coil is wound on a magnetic core in a spiral upward mode, the inner coil and the outer coil are wound by one litz wire, and the winding directions of the inner coil and the outer coil are opposite. The double-solenoid type transmitting guide rail changes the magnetic field distribution of the planar rectangular transmitting guide rail, so that the transmitting power of the coupling mechanism has good stability when the pick-up coil is in the guide rail switching domain and generates large-range transverse offset. And (5) constructing simulation models of the double-emission-plane rectangular coupling mechanism and the double-solenoid type coupling mechanism by using COMSOL finite element simulation software to analyze mutual inductance fluctuation trend, wherein parameters of the simulated coupling mechanism are shown in a table 5.
Table 5 simulation parameter table for two guide rail structures
Figure BDA0003754593030000161
Fig. 13 and 14 are magnetic field distribution cloud diagrams of two coupling mechanisms respectively, and it is easy to see by comparison that in the travelling direction of the electric automobile, i.e. in the x direction, the magnetic field intensity of the planar rectangular coupling mechanism is obviously weakened in the guide rail switching domain, so that mutual inductance falls off, while the magnetic field intensity of the double-solenoid coupling mechanism is uniformly distributed in the x direction, and no obvious mutual inductance falling area exists; in the transverse offset direction, namely in the y direction, the magnetic field intensity of the planar rectangular coupling mechanism is strong in the center area of the transmitting guide rail, the magnetic field intensity of two sides of the planar rectangular coupling mechanism is gradually weakened, the magnetic field intensity of the double-solenoid type coupling mechanism is weaker in the center area of the transmitting guide rail, the magnetic field intensity of two sides of the planar rectangular coupling mechanism is stronger, and when an electric automobile transversely offsets, the mutual inductance of the double-solenoid type coupling mechanism falls down slowly, so that the anti-offset performance is better. The change in mutual inductance of the drawn planar rectangular coupling mechanism and the double solenoid type coupling mechanism in the x-direction and the y-direction is shown in fig. 15.
As can be seen by comparing the mutual inductance changes of the two coupling mechanisms in different directions in fig. 15, the mutual inductance of the planar rectangular coupling mechanism at the opposite position of the transmitting guide rail is slightly larger than that of the double-solenoid coupling mechanism, but the mutual inductance stability of the double-solenoid coupling mechanism is obviously better when the guide rail is switched to the domain and the transverse offset occurs, so that the coupling mechanism has better performance in the aspect of resisting power drop, and the coupling mechanism is continuously optimally designed from the aspects of a magnetic core structure and the number of turns of coils.
A large air gap exists between the transmitting guide rail and the energy pickup coil of the wireless electric energy transmission system, and the magnetic coupling mechanism is in a loose coupling state, so that magnetic force lines of the system not only need to pass through the inside of the magnetic core, but also need to pass through the air gap. The magnetic permeability of the magnetic core is far greater than the air gap, and the magnetic resistance of a magnetic flux path can be effectively reduced by establishing an equivalent magnetic circuit model of the magnetic coupling mechanism to qualitatively analyze the magnetic field distribution around the magnetic coupling mechanism, so that the magnetic core optimization design is guided. A cross-sectional view of the y-z plane of the established coupling mechanism when the pick-up coil is located in the center region of the transmit rail is shown in fig. 16.
The magnetic force lines can be divided into two parts of self-coupling and mutual coupling according to the fact that whether the transmitting coil is coupled with the pick-up coil or not is neglected, and the magnetic fields of the double-solenoid magnetic coupling mechanism are symmetrically distributed along the central plane of the x direction and the y direction and the magnetic fields of the double-solenoid magnetic coupling mechanism are symmetrically distributed along the central axis, so that the double-solenoid magnetic coupling mechanism can be approximately truncated The surface magnetic field distribution is used for analyzing the magnetic field characteristics of the system, and the two-dimensional section magnetic field distribution and self-coupling and mutual coupling areas of the double-solenoid magnetic coupling mechanism are shown in fig. 16. Let the magnetic resistances of self-coupling region 1 and self-coupling region 2 be R respectively s1 And R is s2 The magnetic resistances of the mutual coupling region 1 and the mutual coupling region 2 are respectively R m1 And R is m2 The magnetomotive force of the system is F, and an equivalent magnetic circuit model is established as shown in FIG. 17.
Analysis of equivalent magnetic circuit model of y-z section by
Figure BDA0003754593030000171
Representing the total magnetic flux on one side of the cross section, ">
Figure BDA0003754593030000172
The self-coupling magnetic flux and the mutual coupling magnetic flux on one side of the section are respectively shown, and then the relation between the magnetic fluxes is as follows:
Figure BDA0003754593030000173
the magnetic circuit expression of the coupling coefficient K can be expressed as:
Figure BDA0003754593030000181
simplifying to obtain:
Figure BDA0003754593030000182
as can be seen from equation (0.24), the magnetic resistance R of the mutual coupling region m1 、R m2 The smaller the magnetic resistance R of the self-coupling region s1 、R s2 The larger the system coupling coefficient K is, the larger it is. Therefore, the magnetic core structure design flow is shown in fig. 18, and the shape structure and the position arrangement of the magnetic core can be changed, so that the magnetic resistance of the mutual coupling area is reduced, the magnetic resistance of the self-coupling area is increased, and the coupling coefficient of the system is further improved.
According to the design optimization flow of the magnetic core, the magnetic core on the mutual coupling magnetic path is added, the magnetic core structure of the energy pickup mechanism after optimization is shown as a magnetic core structure of fig. 19 (a), the designed magnetic core convex part is designed according to the trend of magnetic lines in fig. 16, the magnetic resistance of the mutual coupling area is reduced by adding the magnetic core on the mutual coupling magnetic path, and the coupling coefficient is improved to a certain extent. In addition, the greater the number of cores in the magnetic coupling mechanism, the greater the coupling capability of the system. However, the weight, cost, etc. of the system are proportional to the number of magnetic cores, and the amount of magnetic cores should be reduced as much as possible on the premise of ensuring the power transmission capability of the system, so that the amount of magnetic cores of the transmitting rail is reduced, as shown in fig. 19 (b).
It can be seen that the square tubular magnetic core comprises an inner square tubular magnetic core, a middle square tubular magnetic core and an outer square tubular magnetic core which are separated, the inner energy emission solenoid is wound on the inner wall of the inner square tubular magnetic core, and the outer energy emission solenoid is wound on the outer wall of the outer square tubular magnetic core;
the center position of the receiving end magnetic core is provided with a square bulge, and the square bulge is embedded with a square gap in the center of the pick-up coil.
In order to verify the above conclusion, the coupling coefficient sizes and the variation conditions of the systems before and after optimization at different positions are compared through COMSOL simulation analysis, the coupling coefficients before and after magnetic core optimization are shown in FIG. 20, and simulation parameters are the same as in Table 5.
As can be seen from fig. 20, the coupling coefficient of the magnetic core after optimization is obviously improved, and the coupling coefficient of the magnetic core is larger than that of the magnetic core structure before optimization at different offset distances. The magnetic field distribution of the double-solenoid type coupling mechanism is analyzed, the magnetic circuit expression of the coupling coefficient is deduced by establishing an equivalent magnetic circuit model, and the magnetic core structure is optimally designed according to the magnetic circuit expression, so that the coupling coefficient of the system is effectively improved, and the charging efficiency of the system is further improved.
In practical engineering application, the size of the electromagnetic coupling mechanism is strictly limited by practical application scenes, so that after the magnetic core structure and the coil winding shape are determined, the number of turns of the coil needs to be considered. Aiming at the double-solenoid type coupling mechanism, the invention also provides a parameter design method of the double-solenoid type coupling mechanism, firstly, on the basis of the given target mutual inductance size, the optimal design is carried out on the number of turns of the coil by combining the size of the magnetic core so as to obtain enough mutual inductance M; secondly, the size of the coil in the transmitting guide rail is designed, the stability of the mutual inductance M under the condition of the guide rail switching field and the offset is further improved, a specific optimal design flow is shown in a figure 21, and the method comprises the following steps:
A1, target mutual inductance value M of given design min A transmission distance h;
a2, determining n by combining the sizes of the outer square tubular magnetic core and the receiving end magnetic core 1 Maximum value (n) 1 ) max 、n 2 Maximum value (n) 2 ) max ；
A3, let n 1 ＝n 2 =1, calculating the mutual inductance M of the magnetic coupling mechanism by means of COMSOL finite element simulation software;
a4, judging whether M is larger than M min If yes, recording the current n 1 、n 2 If not, entering the next step;
A5、n 2 adding 1, i.e. n 2 ＝n 2 +1；
A6, judging the current n 2 Whether or not it is greater than (n) 2 ) max If not, returning to the step A4, and if so, entering the next step;
a7, let n 2 ＝1，n 1 Adding 1, i.e. n 1 ＝n 1 +1；
A8, judging the current n 1 Whether or not it is greater than (n) 1 ) max If not, returning to the step A4, if yes, the design fails.
At the time of determining n 1 、n 2 The coil size of the energy-emitting solenoid is then determined by:
b1, combining the power level of the system, and giving the number of turns of the coil in the transmitting guide rail and the maximum drop delta M of mutual inductance during deflection max Giving an initial value of the coil size;
b2, simulating the anti-offset characteristic of the system;
b3, analyzing whether the drop delta M of mutual inductance in the offset is smaller than delta M max If yes, recordAnd if not, adjusting the coil size and returning to the step B2.
According to the Neumann mutual inductance calculation formula, the mutual inductance of the coil is in direct proportion to the number of turns. Simulation analysis shows that the mutual inductance of the double-solenoid magnetic coupling mechanism mainly depends on the number of turns of the outer coil and the number of turns of the pick-up coil of the transmitting guide rail, and the number of turns of the inner coil has little influence on the mutual inductance. The main function of the inner coil of the transmitting guide rail is to change the trend and distribution of magnetic force lines, so that the inner coil has an important influence on the anti-deflection performance of the system. Therefore, the number of turns of the outer coil and the number of turns of the pick-up coil of the transmitting guide rail are mainly considered when the number of turns of the coil is designed, and when the number of turns of the coil in the transmitting guide rail is 0 and the number of turns of the pick-up coil is different, the mutual inductance M of the system changes along with the number of turns of the outer coil of the transmitting guide rail, as shown in fig. 22. As can be seen from an analysis of fig. 22, when the number of turns of the pick-up coil is fixed, the mutual inductance of the coupling mechanism is proportional to the number of turns of the outer coil of the transmitting rail; the more turns of the pick-up coil, the greater the mutual inductance of the coupling mechanism. However, as the number of turns increases, the weight and cost of the magnetic coupling mechanism also increase, and the system loss increases, so the amount of wires used should be reduced as much as possible on the premise of ensuring the mutual inductance. According to the design flow shown in fig. 11, the optimal number of turns of the outer coil and the pick-up coil of the transmitting rail is 8 turns and 15 turns, respectively, with 10 muh as the target mutual inductance value.
Fig. 23 plots the variation of the coupling coefficient K with the number of turns of the outer coil of the transmitting rail and the number of turns of the pick-up coil, with the increase of the number of turns of the outer coil of the transmitting rail, the coupling coefficient of the system decreases first and then becomes stable, and when the number of turns of the outer coil of the transmitting rail is greater than 5 turns, the coupling coefficient remains substantially unchanged. Although the coupling coefficient of the system is larger when the number of turns of the outer coil of the transmitting guide rail is smaller, the mutual inductance M is too small to meet the power transmission requirement of the system. Comparing the coupling coefficients when the number of turns of the pick-up coil is different, it can be found that the number of turns of the pick-up coil has little effect on the coupling coefficient of the system.
In order to improve the anti-offset performance of the system, the size of the coil in the transmitting guide rail is simulated and designed on the basis that the outer coil of the transmitting guide rail is 8 turns and the pick-up coil is 15 turns. The optimal dimensions of the inner coil are not the only ones, but when the inner coilAfter the length is determined, the width has an optimal design value. By combining the size of the magnetic core, the width L of the inner coil is simulated and optimized on the premise that the length of the inner coil is 400mm, and the mutual inductance M of the transmitting guide rail 1, the transmitting guide rail 2 and the pick-up coil is drawn p1s 、M p2s And the change curve of the total equivalent mutual inductance M is shown in fig. 24.
The mutual inductance M at different widths L is shown in FIG. 24 (a) p1s 、M p2s Along with the change trend of the pick-up coil moving along the x direction, the influence of the coil width in the transmitting guide rail on the mutual inductance is mainly concentrated at the center position of the guide rail, and the larger the inner coil width L is, the smaller the mutual inductance M of the system is. After crossing the center position of the track switching field, the mutual inductance of the pick-up coil with the previous firing track is hardly affected by the inner coil width anymore. Fig. 24 (b) shows the fluctuation characteristic of the total equivalent mutual inductance M in relation to the inner coil width L, and when l=50 mm, the fluctuation of M is minimum, so the size of the inner coil of the transmitting rail is designed to 400mm×50mm. In summary, specific parameters of the dual solenoid type coupling mechanism designed herein are shown in table 6.
Table 6 design parameter table for double solenoid type coupling mechanism
Figure BDA0003754593030000211
The three-dimensional curves of mutual inductance of the planar rectangular magnetic coupling mechanism and the double-solenoid magnetic coupling mechanism under different offset conditions are drawn as shown in fig. 25.
As can be seen from the figure, the double-solenoid magnetic coupling mechanism designed in the invention greatly improves the mutual inductance drop problem of the planar rectangular magnetic coupling mechanism in the guide rail switching domain, and improves the anti-offset capability of the system to a certain extent.
It should be further noted that, in this embodiment, the dual-solenoid coupling mechanism is applied to dynamic charging of an electric vehicle as an example, but the implementation of the present invention is not limited to the field of electric vehicles, and is not limited to dynamic charging, and when the coupling mechanism has only one section of dual-solenoid transmitting rail and receiving mechanism (i.e. static charging), the anti-offset capability of the system can be improved, so as to realize the stability of output power in the charging process.
The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.

Claims (6)

1. The parameter design method of the double-solenoid type coupling mechanism comprises a transmitting structure and a receiving structure, wherein the transmitting structure comprises a double-solenoid type transmitting guide rail, the double-solenoid type transmitting guide rail comprises a square tubular magnetic core perpendicular to a road surface, and an inner energy transmitting solenoid and an outer energy transmitting solenoid which are respectively wound on the inner wall and the outer wall of the square tubular magnetic core in a spiral mode, and the inner energy transmitting solenoid and the outer energy transmitting solenoid are wound by the same litz wire but are wound in opposite directions; the receiving structure comprises pickup coils, a receiving end magnetic core and a metal shielding plate which are arranged in a hierarchical mode, and the pickup coils are of square annular structures; the parameter design method is characterized by comprising the following steps:
recording the number of turns of the external energy emitting solenoid as n 1 The number of turns of the pick-up coil isn 2 Is determined by the following stepsn 1 、n 2 ：
A1, target mutual inductance value of given designM min Transmission distanceh；
A2, combining the sizes of the outer square tubular magnetic core and the receiving end magnetic core to determinen 1 Maximum value of [ (]n 1 ) max 、n 2 Maximum value of [ (]n 2 ) max ；
A3, ordern 1 =n 2 =1, calculating the mutual inductance of the double-solenoid type coupling mechanism by means of COMSOL finite element simulation softwareM；
A4, judgingMWhether or not to useGreater thanM min If yes, recording the currentn 1 、n 2 If not, entering the next step;
A5、n 2 adding 1, i.en 2 =n 2 +1；
A6, judging the currentn 2 Whether or not is greater than%n 2 ) max If not, returning to the step A4, and if yes, entering the next step;
a7, ordern 2 =1，n 1 Adding 1, i.en 1 =n 1 +1；
A8, judging the currentn 1 Whether or not is greater than%n 1 ) max If not, returning to the step A4, if yes, failing to design;
at a certain positionn 1 、n 2 Thereafter, the coil width of the internal energy emitting solenoid is determined by:
b1, in combination with the system power level, giving the coil turns of the internal energy emitting solenoid and the maximum sag of mutual inductance at offsetΔM max Giving an initial value of the coil width;
b2, simulating the anti-offset characteristic of the system;
b3, drop of mutual inductance during analysis of deflectionΔMWhether or not to be smaller thanΔM max If yes, recording the current coil width, otherwise, adjusting the coil width and returning to the step B2.
2. The method for designing parameters of a dual solenoid type coupling mechanism according to claim 1, wherein:
the square tubular magnetic core comprises an inner square tubular magnetic core, a middle square tubular magnetic core and an outer square tubular magnetic core which are separated, the inner energy emission solenoid is wound on the inner wall of the inner square tubular magnetic core, and the outer energy emission solenoid is wound on the outer wall of the outer square tubular magnetic core.
3. The method for designing parameters of a dual solenoid type coupling mechanism according to claim 2, wherein:
the center position of the receiving end magnetic core is provided with a square bulge, and the square bulge is embedded with a square gap in the center of the pick-up coil.
4. The method for designing parameters of a dual solenoid type coupling mechanism according to claim 1, wherein:
the double-solenoid type emission guide rail is provided with a plurality of emission guide rails which are equidistantly distributed along the road direction.
5. The method for designing parameters of a dual solenoid type coupling mechanism according to claim 1, wherein: and the inner energy emission solenoid, the outer energy emission solenoid and the pickup coil are wound by litz wires with the specification of 0.1mm by 1000 strands and the outer diameter of 5 mm.
6. The method for designing parameters of a dual solenoid type coupling mechanism according to claim 1, wherein: the square tubular magnetic core and the receiving end magnetic core are made of manganese-zinc ferrite made of PC95 materials.
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103986245A (en) * 2014-06-04 2014-08-13 中国矿业大学(北京) Wireless electric energy transmission system and method based on double-layer two-way spiral coils
CN104426247A (en) * 2013-08-29 2015-03-18 丰田自动车株式会社 Power reception device, power transmission device and power transfer system
CN107482790A (en) * 2017-08-04 2017-12-15 河南师范大学 Efficiently positive wireless power supply system design method in parallel
CN111756121A (en) * 2020-07-07 2020-10-09 国网浙江省电力有限公司宁波供电公司 High-power wireless power supply coupling mechanism and parameter design method thereof
CN114161952A (en) * 2021-12-14 2022-03-11 重庆大学 Electric automobile dynamic wireless charging system for restraining power fluctuation through magnetic integration

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020167245A1 (en) * 2019-02-15 2020-08-20 Xnergy Autonomous Power Technologies Pte. Ltd. Wireless power transfer based on magnetic induction

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104426247A (en) * 2013-08-29 2015-03-18 丰田自动车株式会社 Power reception device, power transmission device and power transfer system
CN103986245A (en) * 2014-06-04 2014-08-13 中国矿业大学(北京) Wireless electric energy transmission system and method based on double-layer two-way spiral coils
CN107482790A (en) * 2017-08-04 2017-12-15 河南师范大学 Efficiently positive wireless power supply system design method in parallel
CN111756121A (en) * 2020-07-07 2020-10-09 国网浙江省电力有限公司宁波供电公司 High-power wireless power supply coupling mechanism and parameter design method thereof
CN114161952A (en) * 2021-12-14 2022-03-11 重庆大学 Electric automobile dynamic wireless charging system for restraining power fluctuation through magnetic integration

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
具有强抗偏移性能的电动汽车用无线电能传输系统;王懿杰等;《中国电机工程学报》;第39卷(第13期);3907-3916 *

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