CN114274801B - A method for suppressing output voltage fluctuations of a three-phase dynamic wireless power supply system - Google Patents

Abstract

The present invention proposes a method for suppressing output voltage fluctuations of a three-phase dynamic wireless power supply system based on a short-distance receiving coil. The method uses the short-distance receiving coil to eliminate the harmonic traveling wave magnetic field generated by the three-phase transmitting coil in the receiving coil. Induction voltage, thereby effectively suppressing the fluctuation of output voltage in the three-phase dynamic wireless power supply system and achieving constant output voltage. The output voltage fluctuation suppression method based on the short-distance receiving coil of the present invention is also applicable to wireless power supply transmitting end devices with different structures such as three-phase zigzag transmitting coils and three-phase I-shaped power supply rails.

Description

A method for suppressing output voltage fluctuations of a three-phase dynamic wireless power supply system

Technical field

The invention belongs to the technical field of wireless power transmission, and in particular relates to a method for suppressing output voltage fluctuations of a three-phase dynamic wireless power supply system based on a short-distance receiving coil.

Background technique

Dynamic wireless power supply technology can realize contactless power supply for electric vehicles, rail trains, factory handling equipment and mobile portable equipment. Compared with the traditional wired power supply method, this technology can have the advantages of high safety, waterproof and dustproof, and flexible charging. Under the same transmission distance, the three-phase dynamic wireless power supply system has higher output power than the single-phase system. At the same time, the traveling magnetic field can be used to reduce output power fluctuations, so it is widely used in high-power applications.

Various research institutions at home and abroad have conducted many studies on three-phase dynamic wireless power supply systems, literature [H.Matsumoto, Y.Shibako, Y.Shiihara, R.Nagata and Y.Neba, "Three-Phase Lines to Single-Phase Coil Planar Contactless Power Transformer," in IEEE Transactionson Industrial Electronics, vol.65, no.4, pp.2904-2914, April 2018, doi:10.1109/TIE.2017.2748049.] proposes a three-phase zigzag wireless power supply system. The transmitting end uses a three-phase zigzag transmitting coil, and the receiving end uses a single-phase circular coil. Literature [S.Cui, B.Song, ), Montréal, QC, 2018, pp.1-6, doi:10.1109/WoW.2018.8450657.] proposed a three-phase I-type wireless power supply system, which uses I-type power supply rails to further increase the transmission distance. The patent [Application Publication No. CN 109660032 A] proposes a three-phase receiving end structure, which solves the problem of inconsistent phase voltages due to stacking of three-phase receiving coils. However, the above systems have a common shortcoming: there is output power fluctuation. The harmonic component in the traveling magnetic field generated by the three-phase transmitting coil will generate harmonic induced voltage in the receiving coil. During the movement of the receiving end, the phase difference between the harmonic induced voltage and the fundamental wave induced voltage will change with the receiving end. The location changes. Therefore, the harmonic component in the traveling magnetic field produces a harmonic induced voltage in the receiving coil, which will cause the amplitude of the output voltage at the receiving end to change with the position of the receiving end, thereby causing the output voltage to fluctuate. In a dynamic wireless power supply system, in order to achieve constant voltage/constant current charging of the vehicle battery, it is necessary to ensure that the output voltage of the receiving end is constant. Large output voltage fluctuations will not only increase the design difficulty of the receiving end converter, but also reduce the average output power of the system. Therefore, suppressing output power fluctuations is an urgent problem to be solved in three-phase dynamic wireless power supply technology.

Contents of the invention

The purpose of the present invention is to solve the problem of large output voltage fluctuations in the current three-phase dynamic wireless power supply system and propose a method for suppressing the output voltage fluctuation of the three-phase dynamic wireless power supply system based on a short-distance receiving coil. The method of the present invention uses a short-distance receiving coil to eliminate the induced voltage generated in the receiving coil by the harmonic traveling magnetic field generated by the three-phase transmitting coil, thereby effectively suppressing the fluctuation of the output voltage in the three-phase dynamic wireless power supply system and realizing the output constant voltage. The output voltage fluctuation suppression method based on the short-distance receiving coil of the present invention is also applicable to wireless power supply transmitting end devices with different structures such as three-phase zigzag transmitting coils and three-phase I-shaped power supply rails.

The present invention is realized through the following technical solutions. The present invention proposes a three-phase dynamic wireless power supply system output voltage fluctuation suppression method based on short-distance receiving coils. The method specifically includes the following steps:

Step 1: The transmitter device of the three-phase dynamic wireless power supply system adopts a three-phase transmitting coil, and a three-phase symmetrical high-frequency alternating current is passed into each phase of transmission; the single-phase transmission is obtained through magnetic field analysis calculation or finite element simulation. The magnetic field distribution generated by the coil at the receiving end plane;

Step 2: Perform Fourier decomposition on the magnetic field generated by the single-phase transmitting coil to determine the fundamental wave component and higher harmonic component in the magnetic field. Since the magnetic poles generated by the transmitting coil are N poles and S poles staggered along the driving direction, Therefore, the harmonic magnetic field contains only odd-order components;

Step 3: Design the length of the short-range receiving coil based on the harmonic components in the magnetic field generated by the single-phase transmitting coil. By designing the length of the short-range receiving coil, the induced voltage generated by the harmonic magnetic field in the receiving coil can be eliminated, thereby achieving The purpose is to suppress output voltage fluctuations during dynamic power supply.

Further, the design principles of the short-distance receiving coil are specifically:

(1) Since the 3rd harmonic magnetic field generated by the three-phase transmitting coil will cancel each other in space, the 3rd harmonic magnetic field has no effect on the output voltage fluctuation; when the magnetic field generated by the single-phase transmitting coil only contains the 5th harmonic component, the length of the short-distance receiving coil is designed to be 4τ/5, where τ is the polar distance of the transmitting end. At this time, the induced voltages generated by the fifth harmonic magnetic field in the receiving coil cancel each other out, and the voltage in the receiving coil is only composed of the fundamental wave. The magnetic field is generated. During the movement of the receiving end, the amplitude of the induced voltage generated by the fundamental magnetic field remains unchanged, and the output voltage of the system is constant;

(2) When the magnetic field generated by the single-phase transmitting coil only contains the 7th harmonic component, the length of the short-distance receiving coil is designed to be 6τ/7; similarly, when the magnetic field generated by the single-phase transmitting coil only contains the i-order When the harmonic component is used, where i=5,7,9,11..., the length of the short-distance receiving coil is designed as At this time, the induced voltages generated by the i-th harmonic magnetic field in the receiving coil cancel each other out. The induced voltage in the receiving coil is only generated by the fundamental magnetic field. The output voltage of the system is constant during the movement of the receiving end;

(3) When the magnetic field generated by the single-phase transmitting coil contains only the 5th harmonic component and the 7th harmonic component at the same time, the length of the short-range receiving coil is designed to be 5τ/6. At this time, the short-range receiving coil can suppress both The harmonic induced voltage generated by the 5th harmonic magnetic field and the 7th harmonic magnetic field in the receiving coil achieves the purpose of suppressing the fluctuation of the system output voltage; similarly, when the magnetic field generated by the single-phase transmitting coil only contains the i-th harmonic When there are wave components and i+2 harmonic components, the length of the short-distance receiving coil is designed as At this time, the short-distance receiving coil can simultaneously suppress the induced voltage generated in the receiving coil by the i-order harmonic magnetic field and the i+2-order harmonic magnetic field, achieving the purpose of suppressing the fluctuation of the system output voltage.

Further, the short-distance receiving coil is a rectangular coil, the length of the rectangular coil is l _coil , and the width of the rectangular coil is w _coil . In order to achieve the purpose of suppressing the output voltage fluctuation, the length of the rectangular coil l _coil is based on the magnetic field generated by the single-phase transmitting coil. Depends on the high-order harmonic components in the coil; the rectangular coil width w _coil only affects the amplitude of the induced voltage in the receiving coil and has no effect on suppressing the induced voltage generated by the harmonic magnetic field. Therefore, changing the coil width w _coil only affects the system output voltage. The amplitude has no effect on the fluctuation of the system output voltage; the width of the rectangular coil w _coil is determined according to the transmission power required by the system.

Further, the short-distance receiving coils are all wound with Litz wire or multi-strand enameled wire insulated from each other. The number of turns of the short-distance receiving coils is N _S , where N _S is a positive integer. According to the system The required transmission power is determined.

Further, the short-distance receiving coil is used together with a flat-plate receiving end magnetic core. The flat-type receiving end magnetic core is made of ferrite material and is laid directly above the short-distance receiving coil to restrain the direction of the magnetic force lines. Shield the leakage magnetic field; the size of the flat-plate receiving end magnetic core is greater than or equal to the size of the short-distance receiving coil.

Further, a plurality of the short-distance receiving coils are used in series; the sizes of the multiple short-distance receiving coils connected in series are exactly the same, and two adjacent short-distance receiving coils can be placed closely together or at a certain distance apart. .

The method of suppressing the output voltage fluctuation of the three-phase dynamic wireless power supply system based on the short-range receiving coil according to the present invention has the following beneficial effects: the method according to the present invention can eliminate the generation of the three-phase transmitting coil by reasonably designing the length of the short-range receiving coil. The harmonic traveling wave magnetic field generates the induced voltage in the receiving coil, thereby effectively suppressing the fluctuation of the output voltage in the three-phase dynamic wireless power supply system and achieving a constant output voltage. On the one hand, the method of the present invention can reduce the fluctuation range of the input voltage of the DC/DC converter at the receiving end, and effectively reduce the design difficulty of the DC/DC converter. On the other hand, this method does not require complex control strategies and only requires a reasonable design of the length of the receiving coil in the receiving end device to achieve constant voltage/constant current charging of the vehicle battery, effectively improving the reliability of the system. At the same time, the method described in the present invention is universal and can be applied to dynamic wireless power supply systems with different transmitter end structures such as three-phase meandering transmitting coils and three-phase I-shaped power supply rails.

Description of the drawings

Figure 1 is a flow chart of a method for suppressing output voltage fluctuations in a three-phase dynamic wireless power supply system according to the present invention;

Figure 2 is a schematic structural diagram of the short-distance receiving coil according to the present invention;

Figure 3 is a schematic structural diagram of a three-phase zigzag transmitter coupled with a short-distance receiving coil;

Figure 4 is a front view of Figure 3;

Figure 5 is a schematic diagram of the magnetic field distribution generated by a single-phase transmitting coil on the receiving end plane;

Figure 6 is a phasor diagram of the induced voltage generated by the fundamental traveling wave magnetic field and the harmonic traveling wave magnetic field in a single receiving conductor;

Figure 7 is a schematic diagram of the change curve of the induced voltage in the entire distance receiving coil with the position of the receiving end;

Figure 8 is a schematic diagram of the principle of using a short-distance receiving coil to suppress the 5th harmonic induced voltage;

Figure 9 is a schematic diagram of the principle of using a short-distance receiving coil to suppress the 7th harmonic induced voltage;

Figure 10 is a schematic diagram of the variation curve of the effective value of the output voltage with the position of the receiving end after using the output voltage fluctuation suppression method of the present invention;

Figure 11 is a schematic structural diagram of the short-distance receiving coil according to the present invention when used in conjunction with the receiving end magnetic core;

Figure 12 is a schematic structural diagram when multiple short-distance receiving coils are used in series;

The component names corresponding to the numbers in the figure are as follows:

1——Short-distance receiving coil;

2——Three-phase transmitting coil;

3——Receiver plane;

4——Full-spacing receiving coil;

5——Receiver flat magnetic core;

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

With reference to Figures 1-12, the present invention proposes a method for suppressing output voltage fluctuations of a three-phase dynamic wireless power supply system based on short-distance receiving coils. The method specifically includes the following steps:

Step 1: The transmitter device of the three-phase dynamic wireless power supply system adopts a three-phase transmitting coil, and a three-phase symmetrical high-frequency alternating current is passed into each phase of transmission; the single-phase transmission is obtained through magnetic field analysis calculation or finite element simulation. The magnetic field distribution generated by the coil at the receiving end plane;

Step 2: Perform Fourier decomposition on the magnetic field generated by the single-phase transmitting coil to determine the fundamental wave component and higher harmonic component in the magnetic field. Since the magnetic poles generated by the transmitting coil are N poles and S poles staggered along the driving direction, Therefore, the harmonic magnetic field only contains odd-order components, that is, the 3rd harmonic component, the 5th harmonic component, the 7th harmonic component...;

Step 3: Design the length of the short-range receiving coil based on the harmonic components in the magnetic field generated by the single-phase transmitting coil. By designing the length of the short-range receiving coil, the induced voltage generated by the harmonic magnetic field in the receiving coil can be eliminated, thereby achieving The purpose is to suppress output voltage fluctuations during dynamic power supply.

The design principles of the short-distance receiving coil are specifically:

(1) Since the 3rd harmonic magnetic field generated by the three-phase transmitting coil will cancel each other in space, the 3rd harmonic magnetic field has no effect on the output voltage fluctuation; when the magnetic field generated by the single-phase transmitting coil only contains the 5th harmonic component, the length of the short-distance receiving coil is designed to be 4τ/5, where τ is the polar distance of the transmitting end. At this time, the induced voltages generated by the fifth harmonic magnetic field in the receiving coil cancel each other out, and the voltage in the receiving coil is only composed of the fundamental wave. The magnetic field is generated. During the movement of the receiving end, the amplitude of the induced voltage generated by the fundamental magnetic field remains unchanged, and the output voltage of the system is constant;

(2) When the magnetic field generated by the single-phase transmitting coil only contains the 7th harmonic component, the length of the short-distance receiving coil is designed to be 6τ/7; similarly, when the magnetic field generated by the single-phase transmitting coil only contains the i-order When the harmonic component is used, where i=5,7,9,11..., the length of the short-distance receiving coil is designed as At this time, the induced voltages generated by the i-th harmonic magnetic field in the receiving coil cancel each other out. The induced voltage in the receiving coil is only generated by the fundamental magnetic field. The output voltage of the system is constant during the movement of the receiving end;

(3) When the magnetic field generated by the single-phase transmitting coil contains only the 5th harmonic component and the 7th harmonic component at the same time, the length of the short-range receiving coil is designed to be 5τ/6. At this time, the short-range receiving coil can suppress both The harmonic induced voltage generated by the 5th harmonic magnetic field and the 7th harmonic magnetic field in the receiving coil achieves the purpose of suppressing the fluctuation of the system output voltage; similarly, when the magnetic field generated by the single-phase transmitting coil only contains the i-th harmonic When there are wave components and i+2 harmonic components, the length of the short-distance receiving coil is designed as At this time, the short-distance receiving coil can simultaneously suppress the induced voltage generated in the receiving coil by the i-order harmonic magnetic field and the i+2-order harmonic magnetic field, achieving the purpose of suppressing the fluctuation of the system output voltage.

The short-distance receiving coil is a rectangular coil, the length of the rectangular coil is l _coil , and the width of the rectangular coil is w _coil . In order to achieve the purpose of suppressing the output voltage fluctuation, the length of the rectangular coil l _coil is based on the high magnetic field generated by the single-phase transmitting coil. It depends on the sub-harmonic component; the width of the rectangular coil w _coil only affects the amplitude of the induced voltage in the receiving coil, and has no effect on suppressing the induced voltage generated by the harmonic magnetic field. Therefore, changing the width of the coil w _coil only affects the amplitude of the system output voltage. It has no effect on the fluctuation of the system output voltage; the width of the rectangular coil w _coil is determined according to the transmission power required by the system.

The short-distance receiving coils are all wound with Litz wire or multi-strand enameled wires insulated from each other. The number of turns of the short-distance receiving coils is N _S , where N _S is a positive integer. According to the requirements of the system The transmission power is determined.

The short-distance receiving coil is used together with the flat-plate receiving end magnetic core. The flat-type receiving end magnetic core is made of ferrite material and is laid directly above the short-distance receiving coil to restrain the direction of the magnetic force lines and shield the leakage magnetic field. ;The size of the flat-plate receiving end core is greater than or equal to the size of the short-distance receiving coil.

Multiple short-distance receiving coils can be used in series; when the output voltage of a single short-distance receiving coil cannot meet the requirements of the system, multiple short-distance receiving coils can be used in series; multiple short-distance receiving coils connected in series can be used. The distance from the receiving coil is exactly the same size. Two adjacent short-distance receiving coils can be placed closely together or at a certain distance. Since a single short-distance receiving coil has eliminated the harmonic induced voltage generated by the harmonic magnetic field component in the coil, when multiple short-distance receiving coils are used in series, the total output voltage at the receiving end will not contain harmonic induced voltage components. During the movement of the receiver, the total output voltage of the system can remain constant.

Here’s how it works:

The following uses a dynamic wireless power supply system with a three-phase zigzag transmitter as an example to illustrate the output voltage fluctuation suppression method based on a short-distance receiving coil according to the present invention.

The structural schematic diagram of the three-phase zigzag transmitter is shown in Figure 3 and Figure 4. The structure is composed of three-phase transmitter cables. The transmitting cable is buried under the road surface and laid parallel to the y-axis direction. In a single-phase transmitting cable, the distance between two adjacent conductors is called the polar distance τ. In order to generate a traveling magnetic field, the transmitting coils of each phase are placed with a phase offset of 2τ/3 along the x-axis direction.

After inputting the transmitting end structural parameters of the three-phase dynamic wireless power supply system, the magnetic field distribution generated by the single-phase transmitting coil on the receiving end plane is obtained through finite element simulation. When a constant current is passed into the A-phase transmitting cable, it will The distribution of the magnetic field B _zA generated by the end plane is shown in Figure 5. It can be seen from the figure that in addition to the fundamental magnetic field in B _zA , there are also 3rd, 5th and 7th harmonic magnetic fields. For the i-th harmonic magnetic field, its pole distance τ _i is 1/i of the fundamental pole distance τ. Therefore, the expression of B _zA on the receiving end plane satisfies:

B _z-AΣ (x,y)＝B _z-A1 (x,y)+B _z-A3 (x,y)+B _z-A5 (x,y)+B _z-A7 (x,y) ( 1)

Among them, the expression of the fundamental magnetic field component B _z-A1 satisfies:

The expression of the i-order harmonic component satisfies:

When a symmetrical alternating current flows through the three-phase transmitting coil, the fundamental magnetic field components B _z-A1 , B _z-B1 and B _z-C1 generated on the receiving end plane satisfy the following formula:

In the formula, t is time, ω is angular velocity, and the synthetic magnetic field B _z-∑1 of the fundamental wave magnetic field satisfies:

In the same way, the synthetic magnetic field of the harmonic component can be obtained to satisfy:

It can be seen from the above formula that the resultant magnetic field of the third harmonic component is 0. This shows that the third harmonic magnetic field generated by each phase transmitting coil cancels each other at the receiving end plane and does not contribute to energy transmission.

For a single effective edge with width w _coil in the receiving coil, the induced voltages e ₁ and e _i generated by the fundamental wave synthetic magnetic field and the i-th harmonic synthetic magnetic field in the conductor satisfy:

In the formula, f is the frequency. Therefore, the total induced voltage e _c-∑ in the conductor is:

e _c-∑ ＝e ₁ +e ₅ +e ₇ (8)

In terms of phase difference, the phase difference ψ ₅ between e ₁ and e ₅ satisfies:

The phase difference ψ ₇ between e ₁ and e ₇ satisfies:

It can be seen from equations (9) and (10) that ψ ₅ and ψ ₇ are both related to the location of the conductor. Figure 6 shows the phasor diagram of the induced voltages e ₁ , e ₅ , e ₇ and _ec-∑ in the conductor as a function of the conductor position x.

It can be seen from the figure that every time the conductor is translated along the x-axis direction through a distance of τ/3, the effective value E _Σ of the total induced voltage in the conductor pulses once. When x=kτ/3 (k is a natural number), E _∑ reaches the maximum value:

EΣ _-max ＝E ₁ +E ₅ +E ₇ (11)

And when x=kτ/3+τ/6, E _∑ reaches the minimum value:

EΣ _-min ＝E ₁ -E ₅ -E ₇ (12)

Therefore, during the movement of the receiving end, the 5th and 7th harmonic magnetic fields will generate induced voltages in the receiving coil, causing the output voltage amplitude of the receiving end to change with the position of the receiving end, thus causing output voltage fluctuations. The relationship between the induced voltage in a single conductor and the position of the receiving end is shown in Figure 7.

For an entire distance receiving coil of length τ, the induced voltage of the coil Equal to the induced voltage in the two effective sides/> and/> The sum of , that is:

Therefore, the fluctuation factor of the induced voltage in a fully-spaced receiving coil of length τ is exactly the same as the voltage fluctuation in a single conductor. To sum up, in order to suppress the output voltage fluctuation of the dynamic wireless power supply system, it is necessary to eliminate the harmonic induced voltage generated by the harmonic magnetic field in the receiving coil.

Since the 3rd harmonic magnetic field generated by the three-phase transmitting coil cancels each other in space, the 3rd harmonic magnetic field has no effect on the output voltage fluctuation. When the magnetic field generated by the single-phase transmitting coil only contains the fifth harmonic component, the length of the short-distance receiving coil is designed to be 4τ/5, where τ is the polar distance of the transmitting end. At this time, the two effective edges on the left and right sides of the coil are always at the same magnetic field position in the fifth harmonic magnetic field, as shown in Figure 8. Therefore, the induced voltage generated by the 5th harmonic magnetic field in the two effective sides is exactly the same. For the receiving coil, the 5th harmonic induced voltage in the two effective sides always cancels each other. The induced voltage in the receiving coil is only generated by the fundamental magnetic field. During the movement of the receiving end, the induced voltage generated by the fundamental magnetic field is The amplitude remains unchanged and the output voltage of the system is constant, thus suppressing the fluctuation of the output voltage. After using the short-distance receiving coil, the variation curve of the effective value of the system output voltage with the position of the receiving end is shown in Figure 10.

When the magnetic field generated by the single-phase transmitting coil only contains the 7th harmonic component, the length of the short-distance receiving coil is designed to be 6τ/7. At this time, the left and right effective sides of the coil are always in the same 7th harmonic magnetic field. Under the magnetic field position, as shown in Figure 9. Therefore, the induced voltages generated by the 7th harmonic magnetic field in the two effective sides are exactly the same. For the receiving coil, the 7th harmonic induced voltage in the two effective sides always cancels each other. The voltage in the receiving coil is only generated by the fundamental magnetic field. During the movement of the receiving end, the amplitude of the induced voltage generated by the fundamental magnetic field is If the value remains unchanged, the output voltage of the system is constant, thereby suppressing output voltage fluctuations.

In the same way, when the magnetic field generated by a single-phase transmitting coil only contains the i-th harmonic component, where i = 5, 7, 9, 11..., the length of the short-distance receiving coil should be designed as At this time, the induced voltages generated by the i-th harmonic magnetic field in the receiving coil cancel each other out. The voltage in the receiving coil is only generated by the fundamental magnetic field. The output voltage of the system is constant during the movement of the receiving end.

When the magnetic field generated by the single-phase transmitting coil contains only the 5th harmonic component and the 7th harmonic component at the same time, the length of the short-range receiving coil is designed to be 5τ/6. At this time, the short-range receiving coil can suppress 5 times at the same time. The induced voltage generated by the harmonic magnetic field and the 7th harmonic magnetic field in the receiving coil can suppress the fluctuation of the system output voltage. Similarly, when the magnetic field generated by the single-phase transmitting coil only contains the i harmonic component and i When the +2nd harmonic component is present, the length of the short-distance receiving coil is designed as At this time, the short-distance receiving coil can simultaneously suppress the induced voltage generated in the receiving coil by the i-order harmonic magnetic field and the i+2-order harmonic magnetic field, achieving the purpose of suppressing the system output voltage fluctuation.

The short-distance receiving coil of the present invention can be used together with the receiving end flat magnetic core, as shown in Figure 11. The flat-plate receiving end magnetic core is made of ferrite material and is laid directly above the short-range receiving coil to restrain the direction of the magnetic field lines and shield the leakage magnetic field; the size of the flat-plate receiving end magnetic core should be greater than or equal to the size of the short-range receiving coil.

Multiple short-distance receiving coils according to the present invention can be used in series, as shown in Figure 12. When the output voltage of a single short-range receiving coil cannot meet the requirements of the system, multiple short-range receiving coils can be connected in series and used together. The sizes of the multiple short-range receiving coils are exactly the same, and the two adjacent short-range receiving coils They can be placed closely together or at a certain distance apart; since a single short-distance receiving coil has eliminated the induced voltage generated by the harmonic magnetic field component in the coil, when multiple short-distance receiving coils are used in series, the total voltage at the receiving end The output voltage will not contain harmonic induced voltage components, and the total output voltage of the system can remain constant during the movement of the receiving end.

The above is a detailed introduction to the output voltage fluctuation suppression method of a three-phase dynamic wireless power supply system based on a short-distance receiving coil proposed by the present invention. In this article, specific examples are used to illustrate the principle and implementation of the present invention. The above The description of the embodiments is only used to help understand the method and the core idea of the present invention; at the same time, for those of ordinary skill in the art, there will be changes in the specific implementation and application scope based on the idea of the present invention. As mentioned above, the contents of this specification should not be construed as limitations of the present invention.

Claims (4)

1. A method for suppressing output voltage fluctuations of a three-phase dynamic wireless power supply system based on short-distance receiving coils, characterized in that the method specifically includes the following steps: Step 1: The transmitter device of the three-phase dynamic wireless power supply system adopts a three-phase transmitting coil, and a three-phase symmetrical high-frequency alternating current is passed into each phase of transmission; the single-phase transmission is obtained through magnetic field analysis calculation or finite element simulation. The magnetic field distribution generated by the coil at the receiving end plane; Step 2: Perform Fourier decomposition on the magnetic field generated by the single-phase transmitting coil to determine the fundamental wave component and higher harmonic component in the magnetic field. Since the magnetic poles generated by the transmitting coil are N poles and S poles staggered along the driving direction, Therefore, the harmonic magnetic field contains only odd-order components; Step 3: Design the length of the short-range receiving coil based on the harmonic components in the magnetic field generated by the single-phase transmitting coil. By designing the length of the short-range receiving coil, the induced voltage generated by the harmonic magnetic field in the receiving coil can be eliminated, thereby achieving The purpose of suppressing output voltage fluctuations during dynamic power supply; The design principles of the short-distance receiving coil are specifically: (1) Since the 3rd harmonic magnetic field generated by the three-phase transmitting coil will cancel each other in space, the 3rd harmonic magnetic field has no effect on the output voltage fluctuation; when the magnetic field generated by the single-phase transmitting coil only contains the 5th harmonic component, the length of the short-distance receiving coil is designed to be 4τ/5, where τ is the polar distance of the transmitting end. At this time, the induced voltages generated by the fifth harmonic magnetic field in the receiving coil cancel each other out, and the voltage in the receiving coil is only composed of the fundamental wave. The magnetic field is generated. During the movement of the receiving end, the amplitude of the induced voltage generated by the fundamental magnetic field remains unchanged, and the output voltage of the system is constant; (2) When the magnetic field generated by the single-phase transmitting coil only contains the 7th harmonic component, the length of the short-distance receiving coil is designed to be 6τ/7; similarly, when the magnetic field generated by the single-phase transmitting coil only contains the i-order When the harmonic component is used, where i=5,7,9,11..., the length of the short-distance receiving coil is designed as At this time, the induced voltages generated by the i-th harmonic magnetic field in the receiving coil cancel each other out. The induced voltage in the receiving coil is only generated by the fundamental magnetic field. The output voltage of the system is constant during the movement of the receiving end; (3) When the magnetic field generated by the single-phase transmitting coil contains only the 5th harmonic component and the 7th harmonic component at the same time, the length of the short-range receiving coil is designed to be 5τ/6. At this time, the short-range receiving coil can suppress both The harmonic induced voltage generated by the 5th harmonic magnetic field and the 7th harmonic magnetic field in the receiving coil achieves the purpose of suppressing the fluctuation of the system output voltage; similarly, when the magnetic field generated by the single-phase transmitting coil only contains the i-th harmonic When there are wave components and i+2 harmonic components, the length of the short-distance receiving coil is designed as At this time, the short-distance receiving coil can simultaneously suppress the induced voltage generated in the receiving coil by the i-order harmonic magnetic field and the i+2-order harmonic magnetic field, achieving the purpose of suppressing the system output voltage fluctuation; The short-distance receiving coil is a rectangular coil, the length of the rectangular coil is l _coil , and the width of the rectangular coil is w _coil . In order to achieve the purpose of suppressing the output voltage fluctuation, the length of the rectangular coil l _coil is based on the high magnetic field generated by the single-phase transmitting coil. It depends on the sub-harmonic component; the width of the rectangular coil w _coil only affects the amplitude of the induced voltage in the receiving coil, and has no effect on suppressing the induced voltage generated by the harmonic magnetic field. Therefore, changing the width of the coil w _coil only affects the amplitude of the system output voltage. It has no effect on the fluctuation of the system output voltage; the width of the rectangular coil w _coil is determined according to the transmission power required by the system. 2. The method according to claim 1, characterized in that: the short-distance receiving coils are wound with Litz wire or multi-strand enameled wires insulated from each other, and the number of turns of the short-distance receiving coils is N _S , where N _S is a positive integer, determined according to the transmission power required by the system. 3. The method according to claim 2, characterized in that: the short-distance receiving coil is used together with a flat-type receiving end magnetic core, and the flat-type receiving end magnetic core is made of ferrite material and is laid on a short-distance receiving coil. Just above the receiving coil, it is used to restrain the direction of the magnetic field lines and shield the leakage magnetic field; the size of the flat-plate receiving end magnetic core is greater than or equal to the size of the short-distance receiving coil. 4. The method according to claim 3, characterized in that: a plurality of the short-range receiving coils are used in series; the sizes of the multiple short-range receiving coils connected in series are exactly the same, and two adjacent short-range receiving coils can be Place them closely together or at a certain distance apart.