An EV-DWPT system with a passive coil and its compensation capacitor

Abstract

The present invention relates to the technical field of dynamic wireless charging of electric vehicles, and specifically discloses an EV-DWPT system with a passive coil and its compensation capacitor, which is achieved by placing a passive coil and its compensation capacitor between ground transmitting coils, and configuring the compensation capacitor to achieve stable output power when adjacent transmitting coils are switched. When the pickup coil travels to the switching point of the adjacent transmitting coils, the induced voltage vector at the vehicle-mounted pickup end is composed of two parts: the induced voltage vector provided by the ground transmitting coil and the induced voltage vector provided by the passive coil. The system adjusts the amplitude and phase angle of the induced voltage vector provided by the passive coil by configuring the compensation capacitor of the passive coil, and performs vector synthesis with the induced voltage provided by the transmitting coil, so as to adjust the amplitude of the induced voltage vector at the vehicle-mounted pickup end and achieve stable output power. The system has a simple structure, does not require a power control link, and is more suitable for a fast EV-DWPT system.

Description

Technical Field

[0001] The present invention relates to the technical field of dynamic wireless charging of electric vehicles, and in particular to an EV-DWPT system with a passive coil and a compensation capacitor thereof. Background Art

[0002] Magnetic coupled wireless power transfer (MC-WPT) technology is a commonly used transmission method in wireless charging of electric vehicles (EVs), especially electric vehicle dynamic wireless power transfer (EV-DWPT). This technology can not only increase the range of electric vehicles, but also reduce the capacity of batteries. If 20% of the roads have a 40kW dynamic charging system, the driving range of electric vehicles can be extended by at least 80%. The reduction in on-board battery capacity reduces both vehicle cost and vehicle weight.

[0003] According to the length of the transmitting coil, the EV-DWPT system can be divided into long rail and short rail transmitting coil structures. In the long rail transmitting coil structure, the transmitting coil is much longer than the pickup end. In the short rail transmitting coil structure, the size of the transmitting coil is close to that of the electric vehicle, and the coupling with the pickup coil is more ideal. The short rail transmitting coil structure can power multiple electric vehicles by independently controlling the transmitting coil while avoiding the exposure of the magnetic field of the transmitting coil in the uncharged area. Therefore, the short rail transmitting coil structure helps to improve the efficiency and safety of power transmission in the EV-DWPT system, and has more practical application value.

[0004] Generally speaking, in the output power stable area, the transmitting coil will provide a relatively constant mutual inductance for the on-board pickup end. However, when the on-board pickup end drives to the adjacent transmitting coil switching point, the output power fluctuates due to the decrease in the coupling coefficient between the on-board pickup coil and the transmitting coil. The fluctuation of output power makes it impossible for electric vehicles to charge effectively in the output power drop area, and even affects the life of the battery. In order to solve this problem, many institutions have proposed many research methods, such as placing the original on-board end compensation inductor in the dual LCC topology structure in the adjacent transmitting coil area to form a new energy channel to compensate for the output power drop of the original system; or optimizing the transmitting coil array to achieve a relatively stable mutual inductance between the transmitting and on-board pickup end; or controlling the primary and secondary sides to achieve stable output power. The above methods are complex in structure or require control, and are not suitable for the practical application of EV-DWPT systems. Summary of the invention

[0005] The present invention provides an EV-DWPT output power fluctuation suppression method based on a passive coil, and solves the technical problem of how to simply realize the smooth charging of an electric vehicle during rapid movement.

[0006] In order to solve the above technical problems, the present invention provides an EV-DWPT system with a passive coil and a compensation capacitor thereof, comprising a ground transmitting end, a vehicle-mounted pickup end, a plurality of passive coils and a compensation capacitor of the passive coil, wherein the ground transmitting end comprises a plurality of transmitting coils laid in a segmented guide rail manner, and a passive coil and a compensation capacitor thereof are symmetrically arranged between two adjacent transmitting coils; the parameter configuration requirement of the compensation capacitor makes the passive coil in a weak inductive detuning.

[0007] Preferably, the parameter value of the compensation capacitor is configured by the following steps:

[0008] A1. When the passive coil is not set, the output power stable area and the output power drop area of ​​the ground transmitting end are determined, wherein the output power stable area refers to the guide rail area below the vehicle-mounted pickup end when the system output power is stable, and the output power drop area refers to the switching area of ​​adjacent transmitting coils;

[0009] A2. Determine the length l of the passive coil i 、Width w i and number of turns;

[0010] A3, determining the initial range of the capacitance value of the compensation capacitor;

[0011] A4, placing the vehicle-mounted pickup terminal directly above the passive coil;

[0012] A5, obtaining the system output current change of the vehicle-mounted pickup terminal in the output power drop area within the initial range of the capacitance value;

[0013] A6. Determine in step A5 that the capacitance value range corresponding to the system output current being within the preset fluctuation range of the rated output current is the initial capacitance value range of the compensation capacitor, wherein the rated output current refers to the system output current of the vehicle-mounted pickup terminal when the vehicle-mounted pickup terminal is in the output power stable region;

[0014] A7, within the capacitance value preliminary selection range, determining the capacitance value range in which the phase angle satisfies the system working under the ZPA condition as the final capacitance value range of the compensation capacitor;

[0015] A8. Select a specific capacitance value within the final capacitance value range according to actual needs.

[0016] Preferably, in step A2, the length l of the passive coil is i The number of turns is determined by the following steps:

[0017] A21. Determine an initial range of the length of the passive coil according to the length of the transmitting coil and the distance between two adjacent transmitting coils, and determine an initial range of the number of turns of the passive coil according to actual needs;

[0018] A22, within the initial range of the length and the initial range of the number of turns, determining an optional range of the length and an optional range of the number of turns that do not affect the system output current of the vehicle-mounted pickup terminal when the vehicle-mounted pickup terminal is in the output power stable region;

[0019] A23. Select a set of length and turn values ​​within the optional length range and the optional number of turns range according to actual needs.

[0020] Preferably, the width w of the passive coil is i The same as the width of the transmitting coil.

[0021] Preferably, the ground transmitting end also includes a DC power supply, multiple high-frequency inverters and multiple ground-end resonant circuits, multiple high-frequency inverters are connected in parallel with the DC power supply, each of the high-frequency inverters is connected in parallel to two of the ground-end resonant circuits, and each of the ground-end resonant circuits is connected to one of the transmitting coils.

[0022] Preferably, the ground-end resonant circuit adopts an LCC compensation network.

[0023] Preferably, the vehicle-mounted pickup end includes a pickup coil, a vehicle-mounted resonant circuit, a rectifier and filter circuit, and a load connected in sequence.

[0024] Preferably, the vehicle-mounted resonant circuit adopts an LCC compensation network.

[0025] The present invention relates to the technical field of dynamic wireless charging of electric vehicles, and specifically discloses an EV-DWPT system with a passive coil and its compensation capacitor, which is placed between ground transmitting coils and configured with compensation capacitors to achieve stable output power when adjacent transmitting coils are switched. When the pickup coil travels to the switching point of the adjacent transmitting coils, the induced voltage vector at the vehicle-mounted pickup end is composed of two parts: the induced voltage vector provided by the ground transmitting coil and the induced voltage vector provided by the passive coil. The system adjusts the amplitude and phase angle of the induced voltage vector provided by the passive coil by configuring the compensation capacitor of the passive coil, and performs vector synthesis with the induced voltage provided by the transmitting coil, so as to adjust the amplitude of the induced voltage vector at the vehicle-mounted pickup end and achieve stable output power. The method has a simple structure, does not require a power control link, and is more suitable for a fast EV-DWPT system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram of vector synthesis using a passive coil provided in an embodiment of the present invention, wherein Figure 1 (a) is the structural diagram of the EV-DWPT system with passive coils. Figure 1 (b) is the schematic diagram of the EV-DWPT system with passive coils. Figure 1 (c) is the principle diagram of vector summation;

[0027] Figure 2 is a schematic diagram of a coupling mechanism of an EV-DWPT system with a passive coil and a compensation capacitor thereof provided in an embodiment of the present invention;

[0028] Figure 3 It is a topological structure diagram of an EV-DWPT system with a passive coil and its compensation capacitor provided by an embodiment of the present invention;

[0029] Figure 4 The embodiment of the present invention provides Figure 3 Equivalent circuit diagram of

[0030] Figure 5 is a mutual inductance curve diagram between a transmitting coil and a pickup coil of a conventional EV-DWPT system provided by an embodiment of the present invention;

[0031] Figure 6 is a curve diagram showing the variation of the mutual inductance between the pickup coil, the transmitting coil and the passive coil with the position of the pickup coil in the system provided by an embodiment of the present invention;

[0032] Figure 7 The embodiment of the present invention provides Schematic diagram of the vector at three capacitance values;

[0033] Figure 8 When the pickup coil is at 0 cm, Amplitude and phase change with C i The relationship diagram of the change of capacitance value;

[0034] Fig. 9 When the vehicle-mounted pickup end is at 0 cm, Different from C i Value relationship diagram;

[0035] Fig.10 When the pickup end is at 0 cm, The phase angle of different C i Value relationship diagram;

[0036] Fig.11 C is provided in the embodiment of the present invention i =250nF, the change of system impedance and phase angle at different positions;

[0037] Fig.12is a comparison diagram of the output power of two EV-DWPT systems provided by an embodiment of the present invention;

[0038] Fig.13 is an efficiency comparison diagram of two EV-DWPT systems provided by an embodiment of the present invention;

[0039] Fig.14 : This is a waveform diagram of the system inverter output at different positions of the pickup end provided by an embodiment of the present invention: (a) x=45cm (b) x=30cm (c) x=15cm (d) x=0cm. DETAILED DESCRIPTION

[0040] The following specifically illustrates the implementation mode of the present invention in conjunction with the accompanying drawings. The embodiments are provided for illustrative purposes only and cannot be understood as limiting the present invention. The accompanying drawings are provided for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0041] Figure 1 shows the principle of vector summation, where Figure 1 (a) shows the structure of the EV-DWPT system with passive coils. Figure 1 (b) shows the principle of the EV-DWPT system with passive coils. Figure 1 (c) Schematic diagram showing vector summation. Regardless of the topology used at the vehicle pickup end, the output current Both with the pickup voltage have a fixed phase relationship, the pickup voltage The amplitude of is the most important factor affecting the output current and output power. When the pickup end moves to the adjacent transmitting coil switching point, the pickup voltage drops due to the mutual inductance. The amplitude of is reduced, causing the output power fluctuation at the switching point of the transmitting coil.

[0042] In order to reduce the output power fluctuation at the switching point of the transmitting coil, the embodiment of the present invention proposes an EV-DWPT system with a passive coil and its compensation capacitor based on vector synthesis. A passive coil and its compensation capacitor are added between adjacent transmitting coils. The amplitude and phase of the passive coil current can be adjusted by configuring its compensation capacitor. The induced voltage vector provided by the passive coil The induced voltage vector provided by the transmitting coil By performing vector synthesis, the vehicle pickup end obtains an induced voltage vector with an amplitude close to that in the rated power area. When the vehicle pickup end moves to the power stable area, since the pickup coil and the passive coil are not coupled, the passive coil has little effect on the output power. In this way, the electric vehicle can maintain the power during the entire process of moving above the transmitting coil. The amplitude is stable, achieving stable output power.

[0043] Figure 2 The topology diagram of the EV-DWPT system with a passive coil and its compensation capacitor is shown in Figure 1. The system includes a ground transmitting end, a vehicle-mounted pickup end, multiple passive coils and compensation capacitors of the passive coils. The ground transmitting end includes multiple transmitting coils laid in a segmented rail style, and a passive coil and its compensation capacitor are symmetrically arranged between two adjacent transmitting coils. The ground transmitting end also includes a DC power supply, multiple high-frequency inverters and multiple ground-end resonant circuits. Multiple high-frequency inverters are connected in parallel with the DC power supply, and each high-frequency inverter is connected in parallel to two resonant networks connected to the transmitting coil. The ground-end resonant circuit adopts an LCC compensation network. The vehicle-mounted pickup end includes a pickup coil connected in sequence, a vehicle-mounted resonant circuit, a rectifier filter circuit and a load R L The vehicle-mounted resonant circuit uses an LCC compensation network.

[0044] Figure 3 The coupling mechanism of the EV-DWPT system with a passive coil and its compensation capacitor provided in this embodiment is shown. As an example, the length l of the transmitting coil in this embodiment is 1500mm and the width w is 540mm. The size of the pickup coil is designed to be 600mm*600mm*5mm. The size of the magnetic core at the vehicle end is 600mm*600mm*10mm. The transmission distance d = 200mm, and the gap d between two adjacent transmitting coils is a =5cm.

[0045] Figure 2 The equivalent circuit of the EV-DWPT system with passive coil is as follows: Figure 4 As shown, at the ground end, in order to reduce the cost of power electronic modules, each inverter drives two transmitting coils L ti , i = 1, 2, the mutual inductance between the two transmitting coils is expressed as M t1t2 or M t2t1 In order to improve the filtering effect, C fi Used with C pi , L fi and C ti Together they form a compensation network. Transmitter coil L t and pickup coil L r Mutual inductance M tr In the following, in order to simplify the analysis, the internal resistance of all inductors and capacitors is ignored, and the corresponding mutual inductance M tr is defined as:

[0046] M tr =M t1r +M t2r (1)

[0047] The basic voltage phase sum of the inverter can be expressed as:

[0048]

[0049] To simplify the analysis, the system parameters are assumed to be consistent.

[0050]

[0051] The compensation inductor L at the ground end f′ , the equivalent self-inductance of the transmitting coil L t′ and pickup coil L r′ The equivalent self-inductance can be written as:

[0052]

[0053] ω represents the operating angular frequency of the system. The resonance relationship between the ground terminal and the vehicle terminal is expressed as:

[0054] ω 2 L t′ C p =ω 2 L f′ C p =ω2L r′ C s =ω 2 L s C s =1 (5)

[0055] Passive coil L i Located in a symmetrical position between the two transmitting coils, in the case of multiple coupling, the passive coil L i and the transmitting coil L t M between ti will also have an impact on power transfer, so it cannot be ignored and is expressed as:

[0056] M ti =M t1i +M t2i ,M t1i =M t2i (6)

[0057] Passive coil L i Connect a compensation capacitor, passive coil L i The equivalent self-inductance can be expressed as:

[0058]

[0059] according to Figure 4 The model in the Kirchhoff equation can be established to obtain equation (8):

[0060]

[0061] By substituting equations (4)-(7) into equation (8), the currents of the two transmitting coils can be approximately expressed as:

[0062]

[0063] Due to the characteristics of the LCC topology, the current phase of the transmitting coil is basically constant.

[0064] The current of the passive coil can be obtained:

[0065]

[0066] Among them, A, B, and C are variables used to simplify formula (10), expressed as:

[0067]

[0068] The output current of the system can be derived as:

[0069]

[0070] in

[0071]

[0072] According to formula (12), the phase and amplitude of the passive coil current will affect the output power of the system. According to formula (10), after designing the passive coil, the parameter M is determined. ir and M ti , vector The phase of L i′ can be adjusted by configuring different compensation capacitor values.

[0073] In addition, it is necessary to analyze the system resonance state under multiple coupling effects. The total inverter output current can be derived as:

[0074]

[0075] Similarly, according to equation (14), the phase of the inverter output current can also be changed by configuring different relay capacitor values, which can help the system achieve ZVS.

[0076] When the pickup coil is in the transmitting coil L t1 When the output power is above the stable area, the pickup coil is affected by the passive coil and the transmitting coil L t2 The coupling effect of M is small. ir and M t2r tends to zero, and M tr =M trs, the induced voltage when picking up in the output power stable region can be expressed as:

[0077]

[0078] The output current in the output power stable region can be simplified as:

[0079]

[0080] In the output power drop region, when the pickup coil is located between the two transmitting coils, that is, when the pickup coil is located at x = 0 cm, the output current and output power of the system without the passive coil are the lowest. t1r =M t2r =M trd The case where the mutual inductance M between the passive coil and the pickup coil ir M ird , therefore, the picked-up voltage can be expressed as:

[0081]

[0082] The output current of the pickup coil at this point can be simplified to:

[0083]

[0084] I srd The magnitude of can be described as:

[0085]

[0086] Before designing a passive coil, the output power drop region, i.e., the switching region of adjacent transmitting coils, should be determined. Figure 5 is a graph of the mutual inductance between the transmitting coil and the pickup coil of the traditional EV-DWPT system provided by the embodiment of the present invention. For the traditional EV-DWPT system, Figure 5 The output power drop area within ±37.5cm is given. The width w of the passive coil i The passive coil should be the same as the transmitting coil, which can maintain the lateral misalignment (LTM) characteristics of the original system. The passive coil is located in a symmetrical position between the two transmitting coils, such as Figure 3 shown.

[0087] In the design length l i The passive coil should not affect the transmission in the stable output power area. By traversing the number of turns and length, this example designs a 5-turn passive coil with a size of "150mm*540mm". Figure 6 It is a curve diagram of the change of the mutual inductance between the pickup coil, the transmitting coil and the passive coil with the position of the pickup coil in the system provided by the embodiment of the present invention. Figure 6 shows the change in mutual inductance as the pickup coil moves through its range, M ir Affects the charging area within ±37.5cm.

[0088] After the passive coil design is completed, it is necessary to compensate the capacitance C when the pickup coil is located at x = 0cm. i to configure. Figure 7 Describes The vector synthesis results of the vector under three capacitance values ​​can more clearly describe the results of vector synthesis. i When it is about 125nF, the induced voltage vector provided by the passive coil is and the induced voltage vector provided by the transmitting coil The phases are opposite and the amplitudes are close, so and output power both tend to 0. When C i When the F is 50nF and 250nF, after vector synthesis The amplitude and phase are also different. By adjusting C i The amplitude and phase of the vehicle pickup terminal voltage can be changed.

[0089] Figure 8 When the pickup coil is at 0 cm, Amplitude and phase change with C i The relationship diagram of the change of capacitance value. It can be seen that the compensation capacitor C i Size pair The amplitude and phase have a great impact. It is worth noting that when the passive coil is not coupled with the pickup coil, the passive coil is another load on the transmitter. If the passive coil is resonantly configured, it will form an LCC-S topology with the ground transmitter, which also means that the passive coil is in a no-load state. From equation (14), it can be seen that the inverter current will be too large, posing a safety hazard to the system. i When configuring, ensure that the output current in the power stable area and the output current amplitude in the power drop area are close. When the pickup end is at 0cm, Different from C i The relationship between the values ​​is as follows Fig. 9 As shown. Fig. 9 It can be seen that the passive coil is in the weak inductive working range. near The capacitor should be configured within this operating range (approximately 250-500nF). Therefore, from the perspective of system safety and power transmission, the parameter configuration of the compensation capacitor needs to put the passive coil in a weakly inductive detuned configuration.

[0090] Fig.10When the vehicle-mounted pickup end is at 0 cm, The phase angle at different C i The comparison between the theoretical and simulation results of the value. For the system resonant state, Fig.10 The phase angle of the inverter output current is shown. The reference phase here is During the entire dynamic charging process, it is more important to consider the resonant state of the system than the detuned state of the passive coil. Fig.10 In the figure, the system is divided into capacitive and inductive working areas. Usually, the system works in the weak inductive range, which can help the system achieve ZVS. When it is not coupled with the pickup coil, the weak inductive detuned passive coil will make the system impedance more inductive for the LCC topology of the ground transmitter. Therefore, when the pickup coil is at 0cm, it is only necessary to ensure that the system operates under ZPA conditions. At other locations, the system can still work in the weak inductive range.

[0091] Finally, the embodiment of the present invention determines C i =250nF. Fig.11 It is in C i =250nF, the change diagram of system impedance and phase angle at different positions, from Fig.11 It can be seen that the passive coil and its compensation capacitor given in this example make the amplitude and phase angle of the system impedance meet the design expectations.

[0092] Based on the above analysis, the parameter value of the compensation capacitor is configured through the following steps:

[0093] A1. When no passive coil is set, determine the output power stable area and output power drop area of ​​the ground transmitter. The output power stable area refers to the guide rail area below the vehicle pickup end when the system output power is stable, and the output power drop area refers to the switching area of ​​adjacent transmitting coils;

[0094] A2. Determine the length l of the passive coil i 、Width w i and number of turns;

[0095] A3. Determine the initial capacitance range of the compensation capacitor;

[0096] A4. Make sure the vehicle pickup terminal is located directly above the passive coil;

[0097] A5. Obtain the system output current change when the vehicle pickup terminal is in the output power drop area within the initial range of the capacitance value;

[0098] A6. Determine that the capacitance value range corresponding to the system output current in step A5 being within the preset fluctuation range of the rated output current is the initial selection range of the capacitance value of the compensation capacitor, and the rated output current refers to the system output current when the vehicle-mounted pickup end is in the output power stable region;

[0099] A7. Within the initial range of capacitance value, determine the capacitance value range that satisfies the system working under ZPA conditions as the final capacitance value range of the compensation capacitor;

[0100] A8. Select a specific capacitance value within the final capacitance range based on actual needs.

[0101] In step A2, the length l of the passive coil i The number of turns is determined by the following steps:

[0102] A21. Determine an initial range of the length of the passive coil according to the length of the transmitting coil and the distance between two adjacent transmitting coils, and determine an initial range of the number of turns of the passive coil according to actual needs;

[0103] A22, traverse the initial range of length and the initial range of number of turns, and determine the optional range of length and the optional range of number of turns that do not affect the system output current when the vehicle-mounted pickup end is in the output power stable area;

[0104] A23. Select a set of length and turns values ​​within the optional length range and the optional turns range according to actual needs.

[0105] The width w of the passive coil i Same width as the transmitting coil.

[0106] This embodiment was simulated in MATLAB SimulinkTM to verify the feasibility of the system. The EV-DWPT system with passive coils operates at 85kHz and 380Vdc. Table 1 gives other parameters of the prototype system.

[0107] Table 1 System parameters

[0108] parameter Numeric parameter Numeric <![CDATA[L f1 ,L f2 ]]> 45μH <![CDATA[C p1 ,C p2 ]]> 200nF <![CDATA[C f1 ,C f2 ]]> 160nF <![CDATA[C t1 ,C t2 ]]> 72nF <![CDATA[L r ]]> 84μH <![CDATA[C s ]]> 295nF <![CDATA[L s ]]> 13μH <![CDATA[C r ]]> 50nF <![CDATA[L i ]]> 18μH <![CDATA[M t2t1 ]]> 2.11μH <![CDATA[M t1i ,M t2i ]]> 3.13μH <![CDATA[R L ]]> 12Ω <![CDATA[C i ]]> 250nF

[0109] The output power simulation of EV-DWPT system with and without passive coil is shown in Fig.12 It can be clearly seen that the output power increases from 2.5kW to 10.56kW, which greatly reduces the output power fluctuation in the switching area of ​​adjacent transmitting coils.

[0110] Efficiency simulation of EV-DWPT system with and without passive coil Fig.13 It can be clearly seen that during the entire charging process, the efficiency of the EV-DWPT system with a passive coil can be maintained above 83%, which is another advantage of the system.

[0111] Fig.14The system inverter output waveform at different positions of the pickup end is shown, where (a) x = 45 cm (b) x = 30 cm (c) x = 15 cm (d) x = 0 cm. Fig.14 in, u in is the inverter output voltage. in1 and i in2 is the inverter output current corresponding to the two transmitting coils. in is i in1 and i in2 The total current of the superposition. Due to the addition of the passive coil, the load characteristics of the system reflected on the ground end are different from the original system. Therefore, it is necessary to adjust C t Adjust the system inverter current. During the entire charging process, the total inverter output waveform is always in a resonant state, which limits the reactive power in the resonant circuit and helps the system achieve ZVS.

[0112] In summary, an embodiment of the present invention provides an EV-DWPT system with a passive coil and its compensation capacitor, which achieves stable output power by placing a passive coil and its compensation capacitor between the ground transmitting coils and configuring the compensation capacitor. When the pickup coil travels to the switching point of the adjacent transmitting coil, the induced voltage vector at the vehicle-mounted pickup end is composed of two parts: the induced voltage vector provided by the ground transmitting coil and the induced voltage vector provided by the passive coil. This system adjusts the amplitude and phase angle of the induced voltage vector provided by it by configuring the compensation capacitor of the passive coil, and performs vector synthesis with the induced voltage provided by the transmitting coil, so as to adjust the amplitude of the induced voltage vector at the vehicle-mounted pickup end and achieve stable output power. This method has a simple structure, does not require a power control link, and is more suitable for a fast EV-DWPT system.

[0113] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. An EV-DWPT system with a passive coil and its compensation capacitor, characterized in that: It includes a ground transmitting end, a vehicle-mounted pickup end, a plurality of passive coils and compensation capacitors of the passive coils. The ground transmitting end includes a plurality of transmitting coils laid in a segmented guide rail manner, and a passive coil and its compensation capacitor are symmetrically arranged between two adjacent transmitting coils. The parameter configuration requirement of the compensation capacitor is to make the passive coil in a weak inductive detuning state. The parameter value of the compensation capacitor is configured by the following steps: A1. When the passive coil is not set, the output power stable area and the output power drop area of ​​the ground transmitting end are determined, wherein the output power stable area refers to the guide rail area below the vehicle-mounted pickup end when the system output power is stable, and the output power drop area refers to the switching area of ​​adjacent transmitting coils; A2. Determine the length of the passive coil l i ,width w i and number of turns; A3, determining the initial range of the capacitance value of the compensation capacitor; A4, placing the vehicle-mounted pickup terminal directly above the passive coil; A5, obtaining the system output current change of the vehicle-mounted pickup terminal in the output power drop area within the initial range of the capacitance value; A6. Determine in step A5 that the capacitance value range corresponding to the system output current being within the preset fluctuation range of the rated output current is the initial capacitance value range of the compensation capacitor, wherein the rated output current refers to the system output current of the vehicle-mounted pickup terminal when the vehicle-mounted pickup terminal is in the output power stable region; A7, within the capacitance value preliminary selection range, determining the capacitance value range in which the phase angle satisfies the system working under the ZPA condition as the final capacitance value range of the compensation capacitor; A8. Select a specific capacitance value within the final capacitance value range according to actual needs.

2. An EV-DWPT system with a passive coil and its compensation capacitor according to claim 1, characterized in that: In step A2, the length of the passive coil l i The number of turns is determined by the following steps: A21. Determine an initial range of the length of the passive coil according to the length of the transmitting coil and the distance between two adjacent transmitting coils, and determine an initial range of the number of turns of the passive coil according to actual needs; A22, within the initial range of the length and the initial range of the number of turns, determining an optional range of the length and an optional range of the number of turns that do not affect the system output current of the vehicle-mounted pickup terminal when the vehicle-mounted pickup terminal is in the output power stable region; A23. Select a set of length and turn values ​​within the optional length range and the optional number of turns range according to actual needs.

3. An EV-DWPT system with a passive coil and its compensation capacitor according to claim 2, characterized in that: The width of the passive coil w i The same as the width of the transmitting coil.

4. The EV-DWPT system with a passive coil and its compensation capacitor according to claim 1, characterized in that: The ground transmitting end also includes a DC power supply, multiple high-frequency inverters and multiple ground-end resonant circuits. The multiple high-frequency inverters are connected in parallel with the DC power supply, each of the high-frequency inverters is connected in parallel to two of the ground-end resonant circuits, and each of the ground-end resonant circuits is connected to one of the transmitting coils.

5. The EV-DWPT system with a passive coil and its compensation capacitor according to claim 4, characterized in that: The ground-end resonant circuit adopts an LCC compensation network.

6. The EV-DWPT system with a passive coil and its compensation capacitor according to claim 1, characterized in that: The vehicle-mounted pickup end comprises a pickup coil, a vehicle-mounted end resonant circuit, a rectifier and filter circuit and a load which are connected in sequence.

7. The EV-DWPT system with a passive coil and its compensation capacitor according to claim 6, characterized in that: The vehicle-mounted resonant circuit adopts an LCC compensation network.

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