V2G system based on wireless charging technology

Abstract

The invention discloses a V2G system based on a wireless charging technology. The V2G system is characterized in that an energy storage system battery pack is connected with a bidirectional DCDC converter of a wireless charging pile; the electric vehicle battery pack is connected with a bidirectional DCDC converter in the vehicle-mounted wireless charging system; the bidirectional DCDC converters in the wireless charging pile and the vehicle-mounted wireless charging system are respectively connected with own rectification inversion modules; the rectification inversion module is connected with the resonance compensation circuit, the communication controller is respectively connected with the rectification inversion module and the bidirectional DCDC converter, and the resonance compensation circuit is connected with the wireless charging coil. According to the invention, a wireless charging coil, a resonance compensation circuit, a rectification inversion module, a bidirectional DCDC converter and a communication controller are arranged in the same way; the stable connection of the coil between the wireless charging pile and the vehicle-mounted wireless charging system is ensured, and the charging power is improved. Meanwhile, by adopting an LCC topological structure, a rectification and inversion integrated module and a bidirectional DCDC converter circuit structure, the size and cost of equipment hardware are reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy vehicle charging and wireless charging, and relates to a V2G system based on wireless charging technology. Background Art

[0002] As the number of electric vehicles continues to increase, people are paying more and more attention to the charging problem of electric vehicles. In order to solve the high cost of electric vehicles and the energy storage problem of the power grid, the solution of using electric vehicle battery energy storage has gradually attracted widespread attention, that is, to achieve two-way interaction and exchange between the energy of electric vehicles and the power grid under a controlled state (i.e. V2G-Vehicle to Grid). This solution has better solved the problem of compensation for grid energy storage and high vehicle costs. V2G technology is an important part of smart grid technology. The development of V2G technology will greatly affect the future commercial operation mode of electric vehicles. However, the existing V2G technology is not mature. The voltage optimization process based on V2G electric vehicle charging stations has problems such as uncertain external conditions and nonlinear control results. The existing methods cannot adapt well to the uncertainty of new energy output. Summary of the invention

[0003] The purpose of the present invention is to solve the problems of uncertain external conditions and nonlinear control results in the voltage optimization process of electric vehicle charging stations in the prior art, and to provide a V2G system based on wireless charging technology.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] The V2G system based on wireless charging technology includes: a wireless charging pile and a vehicle-mounted wireless charging system; the wireless charging pile and the vehicle-mounted wireless charging system both include the same wireless charging coil, resonance compensation circuit, rectifier inverter module, bidirectional DCDC converter and communication controller; the wireless charging pile includes a battery pack of an energy storage system; the vehicle-mounted wireless charging system includes a battery pack of an electric vehicle;

[0006] The energy storage system battery pack is connected to the bidirectional DCDC converter of the wireless charging pile; the electric vehicle battery pack is connected to the bidirectional DCDC converter in the on-board wireless charging system; the bidirectional DCDC converters in the wireless charging pile and the on-board wireless charging system are each connected to their own rectifier inverter modules; the rectifier inverter module is connected to the resonant compensation circuit, the communication controller is respectively connected to the rectifier inverter module and the bidirectional DCDC converter, and the resonant compensation circuit is connected to the wireless charging coil.

[0007] A further improvement of the present invention is:

[0008] Furthermore, the rectifier-inverter module comprises a rectifier circuit and an inverter circuit; two ends of the rectifier circuit and the inverter circuit are respectively connected to a resonant compensation circuit and a bidirectional DCDC converter.

[0009] Furthermore, the resonant compensation circuit is a bilateral LCC compensation circuit; and the bidirectional DCDC converter adopts a three-phase Buck-Boost circuit.

[0010] Furthermore, when the charging pile charges the on-board wireless charging system, the bidirectional DCDC converter in the charging pile acts as a BOOST circuit to boost the voltage, and the bidirectional DCDC converter in the on-board wireless charging system acts as a BUCK circuit to step down the voltage; the inverter circuit in the on-board wireless charging system is disconnected and the rectifier circuit is turned on; while the rectifier circuit in the charging pile is disconnected and the inverter circuit is turned on.

[0011] Furthermore, when the on-board wireless charging system charges the charging pile, the bidirectional DCDC converter in the charging pile acts as a BUCK step-down circuit, and the bidirectional DCDC converter in the on-board wireless charging system acts as a BOOST circuit to boost the voltage; the rectifier circuit in the on-board wireless charging system is disconnected and the inverter circuit is turned on; and the inverter circuit in the charging pile is disconnected and the rectifier circuit is turned on.

[0012] Furthermore, before the charging pile charges the on-board wireless charging system, or before the on-board wireless charging system charges the charging pile, the wireless charging coils of the wireless charging pile and the on-board wireless charging system need to be aligned, the wireless charging pile and the on-board wireless charging system communicate, and the communication controllers of the wireless charging pile and the on-board wireless charging system determine whether the charging pile charges the on-board wireless charging system.

[0013] Furthermore, the communication controller between the wireless charging pile and the vehicle-mounted wireless charging system determines whether the charging pile charges the vehicle-mounted wireless charging system based on the following: during peak electricity consumption periods, the vehicle-mounted wireless charging system charges the charging pile; when the on-board battery power of the electric vehicle is less than the warning value, the charging pile charges the vehicle-mounted wireless charging system.

[0014] Furthermore, when the charging pile completes charging the on-board wireless charging system, the communication controller of the on-board wireless charging system disconnects the rectifier circuit of the on-board wireless charging system, and then the communication controller in the wireless charging pile disconnects the inverter circuit of the wireless charging pile.

[0015] Furthermore, when the vehicle-mounted wireless charging system completes charging the charging pile, the communication controller of the vehicle-mounted wireless charging system disconnects the inverter circuit of the vehicle-mounted wireless charging system, and then the communication controller in the wireless charging pile disconnects the rectifier circuit of the wireless charging pile.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The present invention uses the same wireless charging coil, resonance compensation circuit, rectifier inverter module, bidirectional DCDC converter and communication controller to ensure the stable connection of the coil between the wireless charging pile and the on-board wireless charging system, thereby improving the charging power. At the same time, the present invention reduces the volume and cost of the equipment hardware by adopting the LCC topology structure, the rectifier inverter integrated module, and the bidirectional DCDC converter circuit structure; and combines the wireless charging technology with the V2G technology to improve the convenience of the V2G technology of electric vehicles, providing strong technical support for the development of wireless dynamic charging technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 A schematic diagram of a bidirectional wireless charging system between a wireless charging pile and a vehicle-mounted wireless charging system of the present invention;

[0020] Figure 2 A schematic diagram of charging a wireless charging pile to a vehicle-mounted wireless charging system;

[0021] Figure 3 A schematic diagram of charging a wireless charging pile for a vehicle-mounted wireless charging system;

[0022] Figure 4 A schematic diagram of a bidirectional charging and discharging process of a vehicle-mounted wireless charging system and a wireless charging pile of the present invention;

[0023] Figure 5 The circuit topology diagram of the bidirectional wireless charging system;

[0024] Figure 6 It is the control strategy block diagram of three-phase BUCK circuit;

[0025] Figure 7 This is the control algorithm block diagram. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0029] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0030] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0031] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0033] See also Figure 1 The present invention discloses a V2G system based on wireless charging technology, including: a wireless charging pile and a vehicle-mounted wireless charging system; the wireless charging pile and the vehicle-mounted wireless charging system both include the same wireless charging coil, resonance compensation circuit, rectifier inverter module, bidirectional DCDC converter and communication controller; the wireless charging pile includes a battery pack of an energy storage system; the vehicle-mounted wireless charging system includes a battery pack of an electric vehicle;

[0034] The energy storage system battery pack is connected to the bidirectional DCDC converter of the wireless charging pile; the electric vehicle battery pack is connected to the bidirectional DCDC converter in the on-board wireless charging system; the bidirectional DCDC converters in the wireless charging pile and the on-board wireless charging system are each connected to their own rectifier inverter modules; the rectifier inverter module is connected to the resonant compensation circuit, the communication controller is respectively connected to the rectifier inverter module and the bidirectional DCDC converter, and the resonant compensation circuit is connected to the wireless charging coil.

[0035] The rectifier-inverter module includes a rectifier circuit and an inverter circuit; the two ends of the rectifier circuit and the inverter circuit are respectively connected to a resonant compensation circuit and a bidirectional DCDC converter. The resonant compensation circuit is a bilateral LCC compensation circuit; the bidirectional DCDC converter adopts a three-phase Buck-Boost circuit.

[0036] When the charging pile charges the on-board wireless charging system, the bidirectional DCDC converter in the charging pile acts as a BOOST circuit to boost the voltage, and the bidirectional DCDC converter in the on-board wireless charging system acts as a BUCK circuit to step down the voltage; the inverter circuit in the on-board wireless charging system is disconnected and the rectifier circuit is turned on; while the rectifier circuit in the charging pile is disconnected and the inverter circuit is turned on.

[0037] When the on-board wireless charging system charges the charging pile, the bidirectional DCDC converter in the charging pile acts as a BUCK step-down circuit, and the bidirectional DCDC converter in the on-board wireless charging system acts as a BOOST circuit to boost the voltage; the rectifier circuit in the on-board wireless charging system is disconnected and the inverter circuit is turned on; while the inverter circuit in the charging pile is disconnected and the rectifier circuit is turned on.

[0038] Before the charging pile charges the on-board wireless charging system, or before the on-board wireless charging system charges the charging pile, the wireless charging coils of the wireless charging pile and the on-board wireless charging system need to be aligned, the wireless charging pile and the on-board wireless charging system communicate, and the communication controllers of the wireless charging pile and the on-board wireless charging system determine whether the charging pile charges the on-board wireless charging system.

[0039] The communication controller between the wireless charging pile and the on-board wireless charging system determines whether the charging pile charges the on-board wireless charging system based on the following: during peak hours of electricity consumption, the on-board wireless charging system charges the charging pile; when the on-board battery power of the electric vehicle is less than the warning value, the charging pile charges the on-board wireless charging system.

[0040] When the charging pile completes charging the on-board wireless charging system, the communication controller of the on-board wireless charging system disconnects the rectifier circuit of the on-board wireless charging system, and then the communication controller in the wireless charging pile disconnects the inverter circuit of the wireless charging pile.

[0041] When the on-board wireless charging system finishes charging the charging pile, the communication controller of the on-board wireless charging system disconnects the inverter circuit of the on-board wireless charging system, and then the communication controller in the wireless charging pile disconnects the rectifier circuit of the wireless charging pile.

[0042] Example:

[0043] The principle of the electric vehicle bidirectional wireless charging system of the present invention is as follows Figure 1 As shown, the wireless charging pile and the on-board wireless charging system both include the same wireless charging coil, resonant compensation circuit, rectifier inverter module, bidirectional DCDC converter and communication controller; the wireless charging pile includes an energy storage system battery pack; the on-board wireless charging system includes an electric vehicle battery pack; the energy storage system battery pack is connected to the bidirectional DCDC converter of the wireless charging pile; the electric vehicle battery pack is connected to the bidirectional DCDC converter in the on-board wireless charging system; the bidirectional DCDC converters in the wireless charging pile and the on-board wireless charging system are each connected to their own rectifier inverter modules; the rectifier inverter module is connected to the resonant compensation circuit, the communication controller is respectively connected to the rectifier inverter module and the bidirectional DCDC converter, the resonant compensation circuit is connected to the wireless charging coil, wherein the coil of the charging pile and the coil installed on the new energy vehicle have the same specifications and parameters.

[0044] When the charging pile is needed to charge the new energy vehicle, first let the charging pile coil and the new energy vehicle coil face each other, and the charging pile communicates with the on-board wireless charging system. After the controllers on both sides receive the instruction that the charging pile is charging the new energy vehicle, the on-board wireless charging system disconnects the full-bridge inverter circuit and turns on the rectifier circuit that receives energy. Then the charging pile disconnects the rectifier circuit and turns on the full-bridge inverter circuit. First, an instantaneous signal is given to the system. After judging that the charging requirements are met through the detection signal, charging begins. The bidirectional DCDC converter at the charging pile end is used as a BOOST circuit to boost the voltage, and the bidirectional DCDC converter at the new energy vehicle end is used as a BUCK step-down circuit. The charging current and power are controlled by controlling the bidirectional DCDC converters at the charging pile and the new energy vehicle end. The charging process is as follows: Figure 2 When the energy storage system needs to replenish energy during peak hours, the new energy vehicle agrees to use the onboard battery to power the system. The controller controls the switch components in the circuit to make the electric energy flow in the reverse direction, allowing the electric vehicle to discharge and replenish energy for the energy storage system. The process is as follows Figure 3 As shown in Figure 2, the process of charging and discharging energy between electric vehicles and energy storage systems is as follows: Figure 4 shown.

[0045] The resonant compensation circuit of the present invention is a bilateral LCC topology structure, and the circuit topology structure of the bidirectional wireless charging system is as follows: Figure 5As shown, there is no high requirement for the voltage of the energy storage battery pack and the vehicle battery. It is sufficient to ensure that the voltage of the battery packs at both ends is consistent. The low voltage end can still discharge to charge the high voltage end. The receiving circuits on both sides have bidirectional DCDC converter circuits. The control algorithm adopts a dual PI closed-loop control strategy, in which the outer loop controls the output charging current. If the power level is large, the control circuit can use a three-phase BUCK-BOOST circuit. In addition to the control target of stabilizing the current output to the load, the three-phase BUCK-BOOST current sharing condition must also be met.

[0046] The three-phase parallel BUCK circuit has the advantages of large output current and low ripple, but ensuring the balance of current in each phase is an issue that cannot be ignored. Only in this way can the three-phase BUCK circuit work reliably. If the current in each phase is unbalanced for a long time, the service life of the three-phase BUCK converter will be reduced, and even the converter will crash, paralyzing the system. At the same time, the three-phase BUCK circuit must be controlled to ensure the stability of the output current and reduce the current fluctuation of the battery load.

[0047] The reason for the unbalanced inductor current in the three-phase parallel buck circuit is the inconsistency of the equivalent impedance of each phase circuit. This patent adopts a current sharing control method. We already know that the unbalanced current of the three-phase branch is due to the mismatch of the equivalent impedance. We will perform impedance mismatch compensation. The inductor current value of each phase is shown in formula (1):

[0048]

[0049] Where V i = represents the input voltage of the three-phase BUCK, V0 represents the output voltage of the three-phase BUCK, i.e., the battery load voltage, R1, R2, and R3 represent the equivalent impedance of each phase branch, d1, d2, and d3 are the duty cycles of each phase IGBT, and I1, I2, and I3 are the inductor currents of each phase. If the currents of each phase need to be balanced, i.e., to ensure that I1=I2=I3, the equivalent impedance ratios M2=R2 / R1 and M3=R3 / R1 are defined, and thus:

[0050]

[0051] Define the duty cycle as d2=d1+Δd2, d3=d1+Δd3, where Δd2 and Δd3 are the compensation duty cycles. Substituting them into the formula, the compensation duty cycle can be obtained as:

[0052]

[0053] In the three-phase BUCK circuit, the input voltage V iThe output voltage V0 is obtained by sampling through ADC, and the equivalent impedance is measured in advance, so M2 and M3 are fixed constants. In this way, the compensation duty cycles of the second and third phases can be calculated according to the value of the first phase duty cycle d1 to maintain the current balance of each phase, and d1 needs to be calculated according to the requirements of the output current to the load.

[0054] The most important control goal of the three-phase BUCK circuit is to meet the charging current set value I of the load battery. ref , and can reduce the fluctuation of charging current. The method of three-phase current balancing has been given in the previous article. So here we only need to control the stability of single-phase inductor current, that is, control the current of the first phase.

[0055] Ignoring parasitic parameters, the differential equation of the state average model of the single-phase BUCK can be calculated as:

[0056]

[0057] like Figure 6 As shown, C1 and C2 are the front-end and back-end capacitance values ​​of the BUCK circuit respectively, L is the inductance value in the BUCK circuit, i in 、i out and i1 are the input current value, output current value and the inductor current of the first phase of the three-phase BUCK, where i in and i out Measured by Hall sensor.

[0058] Control principle Figure 7 As shown, the outer loop uses a PI controller to control the current of the first-phase BUCK circuit. The control algorithm is as follows:

[0059]

[0060]

[0061] Among them I ref is the given output current control quantity, i out is the actual measured value, e(t) is the single-phase deviation value, K p and K i is the proportional integral parameter of the outer loop PI controller, and the output of the outer loop PI controller It is the input reference value of the inner loop passive control algorithm.

[0062] The passive control algorithm (PBC) is selected for the inner loop because of its advantages of fast dynamic response and low steady-state error. The control algorithm formula is as follows:

[0063]

[0064] like Figure 6 As shown, the duty cycle d1 of the first phase of the three-phase BUCk is obtained by the passive control inner loop, and then the duty cycles d2 and d3 of the second and third phases after compensation are calculated by the three-phase BUCK inductor current sharing control.

[0065] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. The V2G system based on wireless charging technology is characterized by: include: Wireless charging pile and vehicle-mounted wireless charging system; the wireless charging pile and vehicle-mounted wireless charging system both include the same wireless charging coil, resonance compensation circuit, rectifier inverter module, bidirectional DCDC converter and communication controller; the wireless charging pile includes an energy storage system battery pack; the vehicle-mounted wireless charging system includes an electric vehicle battery pack; The energy storage system battery pack is connected to the bidirectional DCDC converter of the wireless charging pile; the electric vehicle battery pack is connected to the bidirectional DCDC converter in the on-board wireless charging system; the bidirectional DCDC converters in the wireless charging pile and the on-board wireless charging system are each connected to their own rectifier inverter modules; the rectifier inverter module is connected to the resonant compensation circuit, the communication controller is respectively connected to the rectifier inverter module and the bidirectional DCDC converter, and the resonant compensation circuit is connected to the wireless charging coil.

2. The V2G system based on wireless charging technology according to claim 1, characterized in that: The rectifier and inverter module comprises a rectifier circuit and an inverter circuit; two ends of the rectifier circuit and the inverter circuit are respectively connected to a resonant compensation circuit and a bidirectional DCDC converter.

3. The V2G system based on wireless charging technology according to claim 2, characterized in that: The resonant compensation circuit is a bilateral LCC compensation circuit; the bidirectional DCDC converter adopts a three-phase Buck-Boost circuit.

4. The V2G system based on wireless charging technology according to claim 3, characterized in that: When the charging pile charges the on-board wireless charging system, the bidirectional DCDC converter in the charging pile acts as a BOOST circuit to boost the voltage, and the bidirectional DCDC converter in the on-board wireless charging system acts as a BUCK circuit to step down the voltage; the inverter circuit in the on-board wireless charging system is disconnected and the rectifier circuit is turned on; while the rectifier circuit in the charging pile is disconnected and the inverter circuit is turned on.

5. The V2G system based on wireless charging technology according to claim 4, characterized in that: When the on-board wireless charging system charges the charging pile, the bidirectional DCDC converter in the charging pile acts as a BUCK step-down circuit, and the bidirectional DCDC converter in the on-board wireless charging system acts as a BOOST circuit to boost the voltage; the rectifier circuit in the on-board wireless charging system is disconnected and the inverter circuit is turned on; while the inverter circuit in the charging pile is disconnected and the rectifier circuit is turned on.

6. The V2G system based on wireless charging technology according to claim 5, characterized in that: Before the charging pile charges the on-board wireless charging system, or before the on-board wireless charging system charges the charging pile, the wireless charging coils of the wireless charging pile and the on-board wireless charging system need to be aligned, the wireless charging pile and the on-board wireless charging system communicate, and the communication controllers of the wireless charging pile and the on-board wireless charging system determine whether the charging pile charges the on-board wireless charging system.

7. The V2G system based on wireless charging technology according to claim 6, characterized in that: The communication controller of the wireless charging pile and the vehicle-mounted wireless charging system determines whether the charging pile charges the vehicle-mounted wireless charging system based on the following: when it is during peak hours of electricity consumption, the vehicle-mounted wireless charging system charges the charging pile; when the on-board battery power of the electric vehicle is less than the warning value, the charging pile charges the vehicle-mounted wireless charging system.

8. The V2G system based on wireless charging technology according to claim 7, characterized in that: When the charging pile completes charging the on-board wireless charging system, the communication controller of the on-board wireless charging system disconnects the rectifier circuit of the on-board wireless charging system, and then the communication controller in the wireless charging pile disconnects the inverter circuit of the wireless charging pile.

9. The V2G system based on wireless charging technology according to claim 8, characterized in that: When the on-board wireless charging system finishes charging the charging pile, the communication controller of the on-board wireless charging system disconnects the inverter circuit of the on-board wireless charging system, and then the communication controller in the wireless charging pile disconnects the rectifier circuit of the wireless charging pile.

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