New energy vehicle charging system and its working method

Abstract

This invention discloses a new energy vehicle charging system and its operating method, relating to the field of electric vehicle charging. This invention aims to address the problems of low charging efficiency, single operating mode, and low power density in existing electric vehicle charging systems. The input unit of this invention includes a DC transmission circuit, an AC transmission circuit, and an on-board wireless power transmission circuit; the energy conversion unit includes a power factor correction circuit A and a DC bus capacitor C connected in sequence. dc Bidirectional CLLLC resonant converter, sustaining capacitor C o The system includes a hybrid energy storage circuit and a power battery. The AC transmission circuit is connected to the power factor correction circuit A, and the DC transmission circuit is connected to switch K. D Connecting to a power battery; this invention can improve the power density of an electric vehicle energy storage system and extend the service life of the power battery.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle charging, and in particular to a charging system for new energy vehicles and its operating method. Background Technology

[0002] To conserve energy and reduce emissions, countries worldwide have begun developing electric vehicles that utilize clean energy. The power battery and charging technology of electric vehicles are crucial aspects of their development. The power battery serves as the energy storage device for an electric vehicle, and its charging technology can be divided into wired charging and wireless charging. Wired charging can be achieved through AC or DC charging; wireless charging eliminates the need for charging cables. Currently, electric vehicle charging typically uses 220V single-phase AC power, which is converted to DC power by a charger to charge the power battery. This method is commonly used in home charging facilities and small charging stations. However, most chargers currently operate primarily under single-phase input conditions, resulting in low output power and long charging times, making it difficult to meet the demands of emergency operation and long driving ranges. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a new energy vehicle charging system and its operating method, which can improve the power density of electric vehicle energy storage systems and extend the service life of power batteries.

[0004] The first aspect of this invention provides a charging system for new energy vehicles, including a wireless power transmission device and an on-board device. The on-board device includes an input unit, an energy conversion unit, and a power battery. The input unit includes a DC transmission circuit, an AC transmission circuit, and an on-board wireless power transmission circuit. The energy conversion unit includes a power factor correction circuit A and a DC bus capacitor C connected in sequence. dc Bidirectional CLLLC resonant converter, sustaining capacitor C o The system includes a hybrid energy storage circuit and a power battery. The AC transmission circuit is connected to the power factor correction circuit A, and the DC transmission circuit is connected to switch K. D Connect the power battery.

[0005] Furthermore, the power factor correction circuit A includes a DC bus capacitor C. dc-s The first bridge arm, second bridge arm, and third bridge arm are identical in structure and connected in parallel. The first bridge arm includes two field-effect transistors connected in series. The DC bus capacitor C dc-s The two ends of the bus are connected in parallel to the two ends of the second bridge arm, and the DC bus capacitor C dc-s A switch K2 is provided between the connection point g of the first bridge arm and the second bridge arm.

[0006] Furthermore, the AC transmission circuit includes single-phase AC transmission and three-phase AC transmission circuits. The single-phase AC transmission circuit includes port a and neutral port N, and the three-phase AC transmission circuit includes port b and port c. Port a is connected to an AC inductor L. a Connect the midpoint of the first bridge arm, and port b is connected through AC inductor L. b Connect the midpoint of the second bridge arm, and port c is connected through AC inductor L. c The neutral terminal N is connected to the midpoint of the third bridge arm via switch K1, and the AC inductor L... c A switch K3 is provided between the connection point g and the third bridge arm, and a switch K4 is provided between the connection point g and the third bridge arm.

[0007] Furthermore, the bidirectional CLLLC resonant converter includes a primary circuit, a transformer, and a secondary circuit. The primary circuit includes two identical primary bridge arms and a primary coil connected in parallel. The two ends of the primary coil are respectively connected to the midpoints of the two primary bridge arms. The secondary circuit includes two identical secondary bridge arms and a secondary coil connected in parallel. The two ends of the secondary coil are respectively connected to the midpoints of the two secondary bridge arms. The two ends of the power battery are connected in parallel across the two ends of the secondary circuit, and the holding capacitor C... o The two ends are connected to the positive and negative terminals of the power battery, respectively;

[0008] The vehicle-mounted wireless power transmission circuit includes a secondary coil and a secondary resonant circuit. The secondary coil is connected in parallel to the two ends of the secondary coil of the bidirectional CLLLC resonant converter via a switch KW.

[0009] The wireless power transmission device includes a power factor correction circuit (B) and a DC bus capacitor (C). dc-w And several parallel-connected fixed wireless power transmission circuits, the fixed wireless power transmission circuits including a primary coil and a primary power circuit.

[0010] Furthermore, the hybrid energy storage circuit includes a field-effect transistor D1, a field-effect transistor D2, and an inductor L. D and supercapacitor S c The drain of MOSFET D1 is connected to the positive terminal of the power battery, the source of MOSFET D1 is connected to the drain of MOSFET D2, and the source of MOSFET D2 is connected to the negative terminal of the power battery. Inductor L... D and supercapacitor S c After being connected in series, it is connected in parallel between the drain and source of the field-effect transistor D2.

[0011] Another aspect of the present invention provides a method for operating a new energy vehicle charging system, based on the new energy vehicle charging system described in the first aspect of the present invention, including a charging mode, wherein the charging mode includes a wired charging mode, and the wired charging mode includes a single-phase AC charging mode, wherein in the single-phase AC charging mode, switches K1, K2, and K3 are closed, and switch K... D When switch K4 is disconnected, the power factor correction circuit A is a cascaded boost circuit of totem-pole power factor correction circuit. The single-phase AC voltage is converted into a stable DC voltage U after passing through the totem-pole power factor correction circuit. dc-s The DC voltage U dc-s The increased DC voltage U is obtained through the boost circuit. dc .

[0012] Furthermore, the wired charging mode includes a three-phase AC charging mode, where switch K... D Switches K1, K2, and K3 are open, and switch K4 is closed, controlling MOSFETs S1 through S6 to make the input current and input voltage have the same phase.

[0013] Furthermore, the charging mode includes a wireless charging mode. In the wireless charging mode, the grid power is transmitted to the vehicle wireless power transmission circuit via the power factor correction circuit B and the fixed wireless power transmission circuit, so that the secondary bridge arm of the bidirectional CLLLC resonant converter works in the rectification state to obtain DC power to charge the power battery.

[0014] Furthermore, the power feedback mode includes a wired power feedback mode and a wireless power feedback mode.

[0015] In the wired power feedback mode, the power battery’s electrical energy is inverted and rectified by a bidirectional CLLLC resonant converter to obtain high-voltage DC power, so that the power factor correction circuit A works in the inverting state to obtain AC power with the same amplitude and phase as the grid voltage, and is output through the AC transmission circuit.

[0016] In the wireless power feedback mode, the electrical energy of the power battery is inverted and rectified by the secondary circuit and primary power circuit of the bidirectional CLLLC resonant converter to obtain high-voltage direct current; the high-voltage direct current is then converted into alternating current with the same amplitude and phase as the grid voltage by the power factor correction circuit B operating in the inverter state.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. This patent proposes a new energy vehicle charging system. By adjusting the closing or closing of each switch of the charging system, the circuit of each unit can work in different states. It can realize not only wired charging mode, but also wireless charging mode. Furthermore, the wired charging mode includes DC wired charging mode, single-phase AC charging mode and three-phase AC charging mode to meet the needs of different occasions.

[0019] 2. The DC charging method of the present invention converts the 380V three-phase AC power of the power grid into DC power, and then charges the power battery directly through the charging cable. Since it is not limited by the space, weight, heat and other conditions in the vehicle, its DC charging output power can reach up to 400kW, which greatly improves the charging efficiency of electric vehicles and saves charging time.

[0020] 3. In the AC charging method of the present invention, when the system is working in AC mode, the power factor correction circuit is switched by a switch, and the circuit topology becomes a totem pole bridgeless power factor correction circuit cascaded with a boost circuit or a three-phase six-switch power factor correction circuit, so that the charging system can be compatible with single-phase and three-phase AC voltage input, the power device utilization rate is high, and it can meet different power occasions.

[0021] 4. When the charging system of the present invention operates in wireless charging mode, it realizes wireless transmission of electrical energy through the magnetic field resonance of the coil. No external charging cable is required during the wireless charging process of electric vehicles. It can adapt to various harsh environments and weather conditions and avoid safety hazards such as leakage.

[0022] 5. The charging system of the present invention can realize multi-directional energy flow. It can not only input electrical energy into the power battery to complete the charging process, but also enable the power battery to feed back electrical energy to obtain AC or DC power, so as to meet the different needs of electric vehicles.

[0023] 6. This invention includes a hybrid energy storage method, which combines supercapacitors and power batteries, effectively extending the lifespan of power batteries and saving costs. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of a new energy vehicle charging system according to a specific embodiment of the present invention;

[0025] Figure 2 This is a circuit diagram of the energy conversion unit according to a specific embodiment of the present invention;

[0026] Figure 3 The circuit diagram of power factor correction circuit A in single-phase AC charging mode is shown in a specific embodiment of the present invention.

[0027] Figure 4 This is a modal diagram of the totem pole power factor correction circuit according to a specific embodiment of the present invention. Figure 4a is the circuit schematic of mode one during the positive half-cycle. Figure 4 b is the circuit schematic of mode two during the positive half-cycle;

[0028] Figure 5 This is a mode diagram of a boost circuit according to a specific embodiment of the present invention. Figure 5 a is the circuit schematic diagram of the S2 conduction mode. Figure 5 b is the circuit schematic diagram of the turn-off mode of switch S2;

[0029] Figure 6 The circuit diagram of power factor correction circuit A in three-phase AC charging mode is shown in a specific embodiment of the present invention.

[0030] Figure 7 This is a circuit diagram of a wireless power transmission device according to a specific embodiment of the present invention. Detailed Implementation

[0031] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0032] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0033] like Figure 1 As shown, the first aspect of the present invention provides a new energy vehicle charging system, including an on-board device and a wireless power transmission device, wherein the on-board device includes an input unit, an energy conversion unit and a power battery;

[0034] The input unit includes a DC transmission circuit, an AC transmission circuit, an on-board wireless power transmission circuit, and a photovoltaic charging circuit. The photovoltaic charging circuit includes a photovoltaic panel and an MPPT (maximum power point tracking) circuit. The AC transmission circuit includes a single-phase AC transmission circuit and a three-phase AC transmission circuit. Single-phase AC charging is a traditional charging method, while three-phase AC charging can provide the system with a larger power angle. DC charging is not limited by the space, weight, or heat conditions of new energy vehicles. The photovoltaic charging circuit serves as an auxiliary power source to provide power to the power battery. Multiple power input methods meet the different charging needs of new energy vehicles.

[0035] like Figure 2 As shown, the energy conversion unit includes a power factor correction circuit A and a DC bus capacitor C connected in sequence. dc Bidirectional CLLLC resonant converter, sustaining capacitor C o The system includes a hybrid energy storage circuit and a power battery. The AC transmission circuit is connected to the power factor correction circuit A, and the DC transmission circuit is connected to switch K. D The photovoltaic charging circuit is connected to the power battery.

[0036] The power factor correction circuit A is used to switch between a single-phase power factor correction circuit and a three-phase power factor correction circuit according to the input voltage type via various switches; as shown in the figure, the power factor correction circuit A includes a DC bus capacitor C. dc-s The first, second, and third bridge arms are identical in structure and connected in parallel. Each bridge arm includes two silicon carbide field-effect transistors (MOSFETs) connected in series. The first bridge arm includes MOSFETs S1 and S4 connected in series; the second bridge arm includes MOSFETs S3 and S6 connected in series; and the third bridge arm includes MOSFETs S5 and S2 connected in series. The DC bus capacitor C... dc-s The two ends of the bus are connected in parallel to the two ends of the second bridge arm, and the DC bus capacitor C dc-s A switch K2 is provided between the connection point g of the first bridge arm and the second bridge arm.

[0037] The AC transmission circuit includes single-phase AC transmission and three-phase AC transmission circuits. The single-phase AC transmission circuit includes port a and neutral port N, and the three-phase AC transmission circuit includes port b and port c. Port a is connected to an AC inductor L. a Connect the midpoint of the first bridge arm, and port b is connected through AC inductor L. b Connect the midpoint of the second bridge arm, and port c is connected through AC inductor L. c The neutral terminal N is connected to the midpoint of the third bridge arm via switch K1, and the AC inductor L... cA switch K3 is provided between the connection point g and the third bridge arm, and a switch K4 is provided between the connection point g and the third bridge arm. The DC bus capacitor C dc The two ends are respectively connected to the two ends of the third bridge arm; the high-voltage DC power output by the power factor correction circuit A passes through the DC bus capacitor C. dc It provides a stable and low-ripple DC bus voltage for subsequent circuits.

[0038] The bidirectional CLLLC resonant converter includes a primary circuit, a transformer T, and a secondary circuit. The primary circuit includes two identical and parallel-connected primary bridge arms, a primary resonant circuit, and a primary coil n. p As shown in the figure, field-effect transistors Q1 and Q3 are connected in series to form the Q1-Q3 bridge arm, and field-effect transistors Q2 and Q4 form the Q2-Q4 bridge arm. The primary-side resonant circuit includes a resonant inductor L. r1 Magnetizing inductance L m and resonant capacitor C r1 The resonant inductor L r1 One end is connected to the midpoint a of the Q1-Q3 bridge arm, and the resonant inductor L r1 The other end is connected to the primary coil n p One end, resonant capacitor C r1 One end is connected to the midpoint b of the Q2-Q4 bridge arm, and the resonant capacitor C... r1 The other end is connected to the primary coil n p The other end; the secondary circuit includes two identical and parallel-connected secondary bridge arms, a secondary resonant circuit, and a secondary coil n. s Field-effect transistors Q5 and Q7 are connected in series to form the Q5-Q7 bridge arm, and field-effect transistors Q6 and Q8 form the Q6-Q8 bridge arm. The secondary resonant circuit includes a resonant inductor L. r2 and resonant capacitor C r2 The resonant inductor L r2 One end is connected to the midpoint c of the Q5-Q7 bridge arm, and the resonant inductor L r2 The other end is connected to the secondary coil n s One end, resonant capacitor C r2 One end is connected to the midpoint d of the Q6-Q8 bridge arm, and the resonant capacitor C... r2 The other end is connected to the primary coil n s At the other end, the resonant element parameter values ​​of the primary and secondary circuits are identical to achieve circuit symmetry, thereby enabling bidirectional power transmission; the two ends of the power battery are connected in parallel to the two ends of the secondary circuit, maintaining the capacitor C o The two ends are connected to the positive and negative terminals of the power battery, respectively.

[0039] The vehicle-mounted wireless power transmission circuit includes a secondary coil R. xand a secondary resonant circuit, the secondary resonant circuit including a resonant inductor L R Resonant capacitor C R1 and resonant capacitor C R The resonant capacitor C R One end is connected to the secondary coil R x One end, resonant capacitor C R The other end is connected to the resonant inductor L R One end, resonant inductor L R The other end is connected to switch K W Connect the midpoint c of the Q5-Q7 bridge arm, and the secondary coil R X The other end is connected to the midpoint d of the Q6-Q8 bridge arm, and the resonant capacitor C R1 One end is connected to the resonant inductor L R With resonant capacitor C R Between them, the other end is connected to the midpoint d of bridge arm Q6-Q8.

[0040] The wireless power transmission device is fixed underground, such as Figure 7 As shown, the wireless power transmission device includes a power factor correction circuit B and a DC bus capacitor C. dc-w As shown in the figure, the power factor correction circuit B includes three identical bridge arms connected in parallel and a DC bus capacitor C. dc-w The series-connected field-effect transistors T1 and T4 form the T1-T4 bridge arm; the series-connected field-effect transistors T3 and T6 form the T3-T6 bridge arm; and the series-connected field-effect transistors T5 and T2 form the T5-T2 bridge arm. The DC bus capacitor C... dc-W The two ends are connected in parallel to the two ends of the T5-T2 bridge arm.

[0041] The fixed wireless power transmission circuit includes a primary coil T. X The circuit includes a primary power circuit and a compensation resonant circuit. The primary power circuit comprises two identical bridge arms connected in parallel, with field-effect transistors Q9 and Q11 connected in series to form Q9-Q11. 11 Bridge arm, MOSFET Q 10 and field-effect transistor Q 12 Series connection constitutes Q 10 -Q 12 Bridge arm;

[0042] The compensation resonant circuit includes a resonant inductor L. T1 Resonant capacitor C T1 and resonant capacitor C T Resonant inductor L T1 One end connects to Q9-Q 11 The resonant inductance L at the midpoint of the bridge arm T1The other end is connected to the resonant capacitor C T Connect the primary coil T x One end of the primary coil T x The other end is connected to Q 10 -Q 12 The midpoint f of the bridge arm, the resonant capacitor C T1 One end is connected to the resonant inductor L T1 With resonant capacitor C T Between, the other end is connected to Q 10 -Q 12 Midpoint f of the bridge arm.

[0043] The hybrid energy storage circuit can effectively extend the life of the power battery, including MOSFET D1, MOSFET D2, and inductor L. D and supercapacitor S c Field-effect transistor D1, field-effect transistor D2, inductor L D This forms a bidirectional DC / DC circuit. The drain of MOSFET D1 is connected to the positive terminal of the power battery, the source of MOSFET D1 is connected to the drain of MOSFET D2, and the source of MOSFET D2 is connected to the negative terminal of the power battery. Inductor L... D and supercapacitor S c After being connected in series, it is connected in parallel between the drain and source of the field-effect transistor D2.

[0044] Based on the above-mentioned new energy vehicle charging system, its working methods include: charging mode, power feedback mode and hybrid energy storage mode.

[0045] The charging mode is the main working process of the charging system. Based on the above charging system, the charging mode is divided into wired charging mode and wireless charging mode. According to the different sources of power, the wired charging mode includes single-phase charging mode, three-phase charging mode and DC charging mode. In the wired charging mode, switch Kw is open.

[0046] In the single-phase AC charging mode, switches K1, K2, and K3 are closed, and switch K... D When switch K4 is disconnected, the power factor correction circuit A is a cascaded boost circuit of totem-pole power factor correction circuit, as shown in the following figure. Figure 3 As shown, the totem pole power factor correction circuit converts a single-phase 220V AC voltage into a DC voltage U. dc-s Its rated value is 400V. Through a cascaded boost circuit, the input voltage of the subsequent resonant converter is made the same in both single-phase and three-phase input modes, thus converting the 400V DC voltage U... dc-s Increased to 700V DC voltage U dc .

[0047] When the totem pole power factor correction circuit is in steady-state operation, one power cycle can be divided into four modes. The two working modes of the positive half-cycle are similar to the two working modes of the negative half-cycle. Taking the two modes of the positive half-cycle of the AC input power supply as an example.

[0048] In operating mode one, MOSFETs S1 and S3 are off, while MOSFETs S4 and S6 are on, and the single-phase voltage U... a Through inductor L a The circuit of MOSFET S4 and MOSFET S6 is connected to inductor L. a During charging, the DC bus capacitor C dc-s Discharge the subsequent circuit;

[0049] In operating mode two, MOSFETs S3 and S4 are off, while MOSFETs S1 and S6 are on, and the single-phase voltage U... a and inductor L a The DC bus capacitor C is controlled through the circuits of MOSFETs S1 and S6. dc-s During charging, the inductor L... a It is in a discharging state.

[0050] When the boost circuit is in steady-state operation, it operates in two modes. In mode one, when the field-effect transistor S2 is turned on, the DC voltage U... dc-s For inductor L c Charging; Mode 2, when MOSFET S2 is turned off, the DC voltage U dc-s and inductor L c The DC bus capacitor C is controlled via the S5 circuit of the field-effect transistor. dc During charging, the inductor L... c It is in a discharging state.

[0051] In the three-phase AC charging mode, switch K D When switches K1, K2, and K3 are open and switch K4 is closed, the power factor correction circuit A is a three-phase six-switch power factor correction circuit, functionally implementing three PWM (Pulse Width Modulation) rectifiers. a U b U c The input voltage is the three-phase mains voltage, and the AC inductance L is... a =L b =L c ,like Figure 6 As shown, during the charging process, by controlling the on / off state of the six field-effect transistors from silicon carbide field-effect transistor S1 to field-effect transistor S6, the input current and input voltage are in phase, and the waveform is approximately a sine wave, thus achieving the purpose of power factor correction.

[0052] In the wireless charging mode, switch Kw When closed, the grid power is transferred to the vehicle-mounted wireless power transfer circuit via the power factor correction circuit B and the fixed wireless power transfer circuit, causing the secondary arm of the bidirectional CLLLC resonant converter to operate in rectification mode, obtaining DC power to charge the power battery; the grid power is rectified by the power factor correction circuit B and then flows through the DC bus capacitor C. dc-w After filtering, a stable DC power supply is provided to the subsequent circuit. The primary coil T... X With secondary coil R X Adjust to the same frequency to achieve energy exchange. Q9-Q 11 Bridge arm and Q 10 -Q 12 The bridge arms form a high-frequency inverter, converting direct current into high-frequency alternating voltage to supply power to the resonant inductor L. T Resonant capacitor C T Resonant capacitor C T1 The LCC compensated resonant circuit consists of a secondary coil R. x Provides high-frequency, high-voltage excitation, with electrical energy flowing from the primary coil T. X Transmitted to the secondary coil Rx, secondary coil R x The compensation resonant circuit on the side converts the received electrical energy into the required output voltage, and then rectifies it through the field-effect transistors Q5-Q7 bridge arms and Q6-Q8 bridge arms to convert the high-frequency AC power into DC power to supply the power battery.

[0053] The power feedback mode includes a grid-connected mode and a DC power feedback mode. The grid-connected mode feeds the power energy in the power battery back to the power grid, while the DC power feedback mode converts the power energy in the power battery into high-voltage DC power to enable functions such as charging other power batteries.

[0054] The grid connection modes include wired and wireless grid connection modes. In the wired grid connection mode, the parameter values ​​of the resonant elements on both the primary and secondary sides of the transformer in the CLLLC resonant converter are identical, ensuring the symmetry of the circuit and enabling bidirectional energy flow, allowing the energy in the power battery to be fed back to the grid. The Q1-Q3 and Q2-Q4 bridge arms constitute the primary-side full-bridge converter, and the Q5-Q7 and Q6-Q8 bridge arms constitute the secondary-side full-bridge converter. At this time, the magnetizing inductance L... m Equivalent to the secondary side of transformer T, the drive signals of field-effect transistors Q5, Q6, Q7, and Q8 are controlled to realize the inverter function; at this time, field-effect transistors Q1, Q2, Q3, and Q4 are not driven by signals, but are rectified by diodes connected in anti-parallel to the field-effect transistors. The power factor correction circuit A works in inverter mode, converting the high-voltage DC power into AC power with the same amplitude and phase as the grid, and feeding energy back to the grid side.

[0055] In wireless grid-connected mode, the LCC compensation resonant network resonant element parameters on both sides of the vehicle-mounted power transmission circuit and the fixed power transmission circuit are identical, ensuring circuit symmetry and enabling bidirectional energy flow, allowing energy from the power battery to be fed back to the grid. At this time, changing the drive signals of MOSFETs Q5, Q6, Q7, and Q8 achieves the inverter function; MOSFETs Q9 and Q... 10 Q 11 Q 12 Without a driving signal, the diodes connected in antiparallel to the field-effect transistors are used for rectification. The power factor correction circuit B operates in inverter mode, converting the high-voltage DC power into AC power with the same amplitude and phase as the grid, and feeding energy back to the grid side.

[0056] The DC feedback mode includes wireless DC feedback mode and wired DC feedback mode. When the power grid fails and cannot provide energy, if multiple electric vehicles are connected to the DC bus interface, the system can realize wireless energy transfer between vehicles.

[0057] In the wireless DC feedback mode, such as Figure 1 As shown, the drive signals controlling MOSFETs Q5, Q6, Q7, and Q8 invert the DC power from the power battery in electric vehicle 1 into high-frequency pulse signals, which are then transmitted to the secondary power circuit 1 via the secondary and primary coils, affecting MOSFETs Q9 and Q8. 10 Q 11 Q 12 The anti-parallel diodes are used for rectification, and the rectified DC bus voltage provides high-voltage DC power to electric vehicle N connected to the DC bus interface.

[0058] In wired DC feedback mode, the drive signals of the control field-effect transistors Q5, Q6, Q7, and Q8 invert the DC power from the power battery in electric vehicle 1 into a high-frequency pulse signal. The electrical energy is then transmitted to the bidirectional CLLLC resonant converter through a transformer, and the diodes connected in antiparallel to the field-effect transistors Q1, Q2, Q3, and Q4 are rectified to obtain high-voltage DC power to charge electric vehicle N.

[0059] When an electric vehicle suddenly accelerates, brakes, or climbs a hill, the power battery is easily damaged, shortening its lifespan. Therefore, this invention adds the aforementioned hybrid energy storage mode, utilizing the characteristics of supercapacitors—low energy density and high power density—to achieve rapid charging and discharging, providing a high-rate current for charging and discharging during vehicle start-stop. When the electric vehicle is in motion, the photovoltaic power supply circuit acts as an auxiliary power source to store energy in the supercapacitor in a timely manner, connecting the supercapacitor with MOSFETs D1 and D2, and inductor L. DAfter forming a bidirectional DC / DC circuit connected in series, it is connected in parallel with the power battery. When the electric vehicle starts or accelerates, the bidirectional DC / DC circuit operates in boost mode, and energy is output from the supercapacitor. When the electric vehicle brakes, the bidirectional DC / DC circuit operates in buck mode, and the supercapacitor can recover braking energy. In other words, depending on the electric vehicle's driving state, the bidirectional DC / DC circuit operates in buck and boost modes to charge and discharge the supercapacitor. This hybrid energy storage method can extend the life of the power battery and reduce costs.

[0060] In summary, the new energy vehicle charging system of this invention is compatible with multiple charging methods, including AC charging, DC charging, and wireless charging, to adapt to different usage scenarios and enable flexible charging of electric vehicles. The AC charging method is compatible with both single-phase 220V and three-phase 380V input voltages, with high utilization of power devices within the charger, meeting the needs of different power applications. The wireless charging method embeds the circuitry and coils underground and automatically connects to the power grid, enabling simultaneous charging of multiple electric vehicles. The hybrid use of supercapacitors and power batteries gives the electric vehicle energy storage system high energy and high power density, extending the lifespan of the power batteries. Therefore, this new energy vehicle charging system has promising application prospects.

[0061] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A new energy vehicle charging system, characterized in that, The system includes a wireless power transmission device and an on-board device. The on-board device includes an input unit, an energy conversion unit, and a power battery. The input unit includes a DC transmission circuit, an AC transmission circuit, and an on-board wireless power transmission circuit. The energy conversion unit includes a power factor correction circuit A and a DC bus capacitor connected in sequence. C dc Two-way CLLLC Resonant converter, sustaining capacitor C o The system includes a hybrid energy storage circuit and a power battery. The AC transmission circuit is connected to the power factor correction circuit A, and the DC transmission circuit is connected via a switch. K D Connect to the power battery; The power factor correction circuit A includes a DC bus capacitor. C dc-s The first bridge arm, second bridge arm, and third bridge arm are identical in structure and connected in parallel. The first bridge arm includes two field-effect transistors connected in series. The DC bus capacitor... C dc-s The two ends of the DC bus capacitor are connected in parallel to the two ends of the second bridge arm. C dc-s A switch is provided between the connection point g of the first and second bridge arms. K 2; The AC transmission circuit includes single-phase AC transmission and three-phase AC transmission circuits. The single-phase AC transmission circuit includes port a and neutral port N, and the three-phase AC transmission circuit includes port b and port c. Port a is connected via an AC inductor. L a Connect the midpoint of the first bridge arm, and connect port b through an AC inductor. L b Connect the midpoint of the second bridge arm, and port c is connected through an AC inductor. L c Connect the midpoint of the third bridge arm, the neutral wire port N is connected via a switch. K 1. A switch is provided between the midpoint of the second bridge arm and the connection point g. K 3. A switch is provided between the connection point g and the third bridge arm. K 4.

2. The new energy vehicle charging system according to claim 1, characterized in that, The bidirectional CLLLC The resonant converter includes a primary circuit, a transformer, and a secondary circuit. The primary circuit includes two identical, parallel-connected primary bridge arms and a primary coil. The two ends of the primary coil are respectively connected to the midpoints of the two primary bridge arms. The secondary circuit includes two identical, parallel-connected secondary bridge arms and a secondary coil. The two ends of the secondary coil are respectively connected to the midpoints of the two secondary bridge arms. The two ends of the power battery are connected in parallel across the two ends of the secondary circuit, and a holding capacitor is used. C o The two ends are connected to the positive and negative terminals of the power battery, respectively; The vehicle-mounted wireless power transmission circuit includes a secondary coil and a secondary resonant circuit, the secondary coil being controlled by a switch. K W Connected in both directions CLLLC The two ends of the secondary coil of the resonant converter; Wireless power transmission devices include power factor correction circuits. B DC bus capacitor C dc-w And several parallel-connected fixed wireless power transmission circuits, the fixed wireless power transmission circuits including a primary coil and a primary power circuit.

3. The new energy vehicle charging system according to claim 1, characterized in that, The hybrid energy storage circuit includes a field-effect transistor. D 1. Field-effect transistor D 2. Inductance L D and supercapacitors S c Field-effect transistor D The drain of 1 is connected to the positive terminal of the power battery, and the field-effect transistor... D 1 source-connected field-effect transistor D 2's drain, field-effect transistor D The source terminal of 2 is connected to the negative terminal of the power battery, and the inductor... L D and supercapacitors S c After being connected in series, it is connected in parallel to the field-effect transistor. D Between the drain and source of 2.

4. The working method of a new energy vehicle charging system, characterized in that, The new energy vehicle charging system based on any one of claims 1-3 includes a charging mode, wherein the charging mode includes a wired charging mode, the wired charging mode includes a single-phase AC charging mode, and in the single-phase AC charging mode, a switch... K 1. Switch K 2 and switch K 3. Close, switch K D and switch K 4. When disconnected, power factor correction circuit A is a cascaded boost circuit of totem-pole power factor correction circuit. The single-phase AC voltage is converted into a stable DC voltage after passing through the totem-pole power factor correction circuit. U dc-s The DC voltage U dc-s The increased DC voltage is obtained through the boost circuit. U dc .

5. The working method of the new energy vehicle charging system according to claim 4, characterized in that, The wired charging mode includes a three-phase AC charging mode, with a switch... K D ,switch K 1. Switch K 2 and switch K 3. Disconnect, switch K 4. Close the circuit and control the field-effect transistor. S 1 to field-effect transistor S 6. Ensure that the input current and input voltage are in phase.

6. The working method of the new energy vehicle charging system according to claim 4, characterized in that, The charging mode includes a wireless charging mode, in which grid power is processed by a power factor correction circuit. B The fixed wireless power transfer circuit transfers electrical power to the vehicle-mounted wireless power transfer circuit, enabling bidirectional transmission. CLLLC The secondary arm of the resonant converter operates in rectification mode, generating direct current to charge the power battery.

7. The working method of the new energy vehicle charging system according to claim 4, characterized in that, The operating method includes a power feedback mode, which includes a wired power feedback mode and a wireless power feedback mode. In the wired power feedback mode, the power battery's electrical energy is transmitted bidirectionally. CLLLC The resonant converter performs inverter rectification to obtain high-voltage direct current, enabling the power factor correction circuit to... A When operating in inverter mode, it generates alternating current with the same amplitude and phase as the grid voltage, which is then output through an AC transmission circuit. In the wireless power feedback mode, the electrical energy of the power battery is transmitted bidirectionally. CLLLC The secondary circuit and primary power circuit of the resonant converter are inverted and rectified to produce high-voltage direct current (HVDC); the HVDC is then passed through a power factor correction circuit operating in inverter mode. B The alternating current with the same amplitude and phase as the grid voltage is obtained.

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