Charging and discharging method and battery replacement device for electric vehicles

Abstract

The present invention provides a charging and discharging method and a battery replacement device for electric vehicles, and the specific steps are: an AC / DC controller monitors the charging demand changes in real time, and provides a timing according to the charging demand of the battery box and the charging pile of the electric vehicle; when the charging pile and the battery box need to be charged at the same time, the AC / DC controller compares the total capacity S of the charging demand of the charging pile and the battery box with the charging capacity S of the AC / DC charging and discharging unit. 0 , complete the corresponding operation; when the charging pile and the battery box do not need to be charged at the same time, the AC / DC controller compares the total capacity S of the charging pile and the battery box with the charging capacity S of the AC / DC charging and discharging unit 0 , complete the corresponding operation; according to the real-time feedback of the battery voltage and current of the charging pile battery management system and the electric vehicle battery box management system, adjust the output voltage and current of the charging pile, and complete the charging. The present invention can not only provide charging and swapping for electric vehicles, but also provide electric energy for the power grid according to the power grid dispatch, effectively improving the utilization rate and economic benefits of the charging and swapping station.

Description

Technical Field

[0001] The present invention relates to the technical field of charging and replacing electric vehicles, and in particular to a charging, discharging and replacing method for electric vehicles and a replacing device thereof. Background Art

[0002] In recent years, with the gradual popularization of electric vehicles, the continuous construction of charging and battery swapping stations, the demand for electricity has gradually increased, which will have a certain impact on the power grid. The demand for power capacity has increased, exacerbating the peak and valley difference in electricity consumption, which has a great impact on the power grid and affects the normal life of residents. Existing charging stations or battery swapping stations only provide charging and battery swapping services for electric vehicles, and fail to interact with the power grid. Electric vehicles and battery swapping boxes cannot be used as energy storage units to discharge for the power grid.

[0003] Among the current charging methods for batteries, there are three mainstream charging methods: the specific implementation process of the constant current and constant voltage charging method is divided into three processes: pre-charging, constant current charging and constant voltage charging. In this method, the polarization of the battery cannot be eliminated, and the charging speed is slow; the specific implementation process of the variable current intermittent charging method is divided into two processes: the variable current intermittent charging stage and the constant voltage charging stage. In this method, the polarization of the battery is reduced during the charging stop period, thereby speeding up the charging speed, but the charging mode circuit is relatively complex and expensive; the specific implementation process of the pulse charging method is consistent with the constant current and constant voltage charging method process, and at the same time, a large current pulse is used to intermittently charge the battery in the pulse charging stage. This method breaks the constraints of the optimal charging current curve on battery charging, has high charging efficiency, small temperature changes, and little impact on battery life, but requires a separate power supply with current limiting function, which greatly increases the charging cost.

[0004] The present invention proposes a charging, discharging and battery swapping method and a battery swapping device for electric vehicles. When the grid load reaches a peak value, the charging and battery swapping container can be used as a large-scale energy storage to provide electric energy for the grid. The charging and battery swapping container can not only provide charging and battery swapping services for electric vehicles, but also provide electric energy for the grid according to grid dispatch, which can more effectively improve the utilization rate and economic benefits of the charging and battery swapping container. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a charging, discharging and battery replacement method for electric vehicles and a battery replacement device thereof. Based on the optimal charging curve, the charging capacity threshold of the AC / DC charging and discharging unit, the charging demand threshold of the charging pile and the charging demand threshold of the electric vehicle battery box are respectively set, and different timings are provided according to the charging requirements of the electric vehicle battery box and the charging pile to complete the charging of the corresponding strategy, thereby improving the charging efficiency of the battery and reducing damage to the battery.

[0006] The present invention provides a charging and discharging method for an electric vehicle, and the specific implementation steps are as follows:

[0007] S1, AC / DC controller according to the charging demand of the electric vehicle battery box S 1 and the charging demand S of the charging pile 2 , monitor the charging demand changes in real time, and provide timing according to the charging demand of electric vehicle battery boxes and charging piles:

[0008] S11. The best charging curve of the current in the battery box or charging pile: According to Maas's law, the expression of the best charging curve is as follows:

[0009] I t =I 0 e -at (1)

[0010] Among them, I 0 Initial current when charging the electric vehicle battery box, I t is the charging current at a certain moment, t is the charging time, and a is the charging acceptance rate;

[0011] According to the battery charging in the battery box or charging pile, the specific expression of the battery capacity Q is as follows:

[0012]

[0013] According to formulas (1) and (2), the expression of the optimal charging curve at a certain moment in the battery box or charging pile is as follows:

[0014] I t =I 0 -aQ; (3)

[0015] S12. Optimal charging curve of the voltage in the battery box or charging pile: According to the battery characteristics and charging requirements, the PNGV (the Partnership for a New Generation of Vehicles) equivalent model of the battery is constructed. The specific expression is as follows:

[0016]

[0017] S t =I t *U t (5)

[0018] Among them, U 0 The initial voltage when charging the electric vehicle battery box, U oc is the open circuit voltage of the battery, U t is the voltage at any time t during the charging process, I t is the current at any time t during the charging process, C Q is the capacitance value of the battery open circuit voltage change, C eis the polarization capacitance value, R 0 is the ohmic internal resistance of the battery, R e is the polarization internal resistance, U e For U T is the rated voltage of the battery box of the electric vehicle, S t Charging energy for electric vehicle battery boxes;

[0019] S2. On the basis of the optimal charging curve in step S1, the charging capacity threshold of the AC / DC charging and discharging unit, the charging demand threshold of the charging pile and the charging demand threshold of the electric vehicle battery box are set respectively. When the charging pile and the battery box require charging at the same time, the charging controller compares the total capacity S of the charging demand of the charging pile and the battery box with the charging capacity S of the AC / DC charging and discharging unit. 0 , and complete the corresponding operations:

[0020] S21, if S 0 ≥S 1 +S 2 When , execute step S4;

[0021] S22, if S 0 <S 1 +S 2 When S is used, the battery box charging demand is reduced. 2 The output of S 0 =S 1 +S 2 , execute step S4;

[0022] S23, if S 0 <S 1 When the battery box is stopped from charging, the battery box is controlled to charge the charging pile through the AC / DC charging and discharging unit, so that S 0 +S 2 =S 1 , execute step S4;

[0023] S3. When the charging pile and the battery box require charging at different times, the AC / DC controller compares the total capacity S of the charging pile and the battery box with the charging capacity S of the AC / DC charging and discharging unit. 0 , and complete the corresponding operations:

[0024] S31. If the AC / DC controller detects that only the battery box needs to be charged, the AC / DC controller compares the charging capacity S of the AC / DC charging and discharging unit. 0 and the battery box charging requirement S 1 , and complete the corresponding operations;

[0025] S32: If the AC / DC controller detects that only the battery box of the electric vehicle needs to be charged, the AC / DC controller compares the charging capacity S of the AC / DC charging and discharging unit.0 and the charging demand S of the charging pile 2 , and complete the corresponding operations;

[0026] S33, if the AC / DC controller does not require charging at the same time, when the AC / DC controller detects that a battery box or a charging pile has added a charging demand, execute step S2;

[0027] S4. According to the battery voltage and current fed back in real time by the electric vehicle battery box management system and the battery swap unit battery box management system, adjust the output voltage and current of the charging pile and complete charging.

[0028] Preferably, in step S23, step S312 or step S322, another charging form is also included, that is, powering the battery of the charging pile or the electric vehicle battery box by closing an idle AC / DC charging and discharging unit or an AC / DC charging and discharging unit with redundant capacity.

[0029] Preferably, the specific steps of step S31 include:

[0030] S311, if S 0 ≥S 1 When , step S4 is executed;

[0031] S312, if S 0 <S 1 When the battery box stops charging, the AC / DC charging and discharging unit controls the battery box to charge the charging pile, so that S 0 +S 2 =S 1 , execute step S4.

[0032] Preferably, the specific steps of step S32 include:

[0033] S321, if S 0 ≥S 2 When , execute step S4;

[0034] S322, if S 0 <S 2 When the AC / DC charging and discharging unit is used to control the battery box to charge the charging pile, S 0 +S 2 =S 1 , execute step S4.

[0035] Preferably, the specific steps of step S4 include:

[0036] S41, the AC / DC controller adjusts the output of the AC / DC charging and discharging unit according to the charging demand voltage and current fed back in real time by the electric vehicle battery box management system, until the output voltage is consistent with the voltage of the battery in the charging pile, the output current is 0, the AC / DC charging and discharging unit stops outputting, starts the standby mode, and completes charging;

[0037] S42, the AC / DC controller adjusts the output of the AC / DC charge and discharge unit according to the charging demand voltage and current fed back in real time by the battery box management system of the battery swap unit, until the output voltage is consistent with the voltage of the electric vehicle battery box and the output current is 0, the AC / DC charge and discharge unit stops outputting, starts the standby mode, and completes charging.

[0038] Another aspect of the present invention provides a charging and discharging battery swapping device for electric vehicles, which includes a high-voltage AC distribution unit, a charging and discharging container and a charging pile, the output end of the high-voltage AC distribution unit is connected to the input end of the charging and discharging container, and the output end of the charging and discharging container is connected to the charging pile; the charging and discharging container includes a battery swapping unit, a charging and discharging unit and a charging and discharging station monitoring unit; the battery swapping unit includes a battery swapping device, a battery box station and a battery swapping station, and the battery swapping device is located between the battery box station and the battery swapping station; the charging and discharging unit includes an AC / DC charging and discharging unit and an AC / DC controller, the first end of the AC / DC controller is connected to the input end of the AC / DC charging and discharging unit, the output end of the AC / DC charging and discharging unit is connected to the battery box station, the second end of the AC / DC controller is connected to the charging pile through a charging pile controller, the AC / DC charging and discharging unit corresponds to multiple battery box stations and charging piles, and the AC / DC charging and discharging unit controls the charging of the corresponding multiple battery box stations and charging piles through the control switch Ki of the AC / DC controller.

[0039] Preferably, the AC / DC controller is connected to a first end of the charging pile controller via a CAN line, and a second end of the charging pile controller is connected to the charging pile via a CAN line.

[0040] Preferably, the number of the AC / DC charging and discharging units, the number of the battery box stations and the number of the charging piles are equal, and each AC / DC charging and discharging unit corresponds to one battery box station and one charging pile.

[0041] Preferably, the number of the charging pile controller is one, and a plurality of the charging piles are connected in parallel to the output end of the charging pile controller.

[0042] Preferably, the AC / DC charging and discharging unit converts the AC power of the grid into DC power and outputs it to the battery box and charging pile at the battery box station for charging, or converts the DC power fed back from the battery box and charging pile at the battery box station into AC power to reversely charge the grid. The charging process and the discharging process cannot be carried out at the same time.

[0043] Compared with the prior art, the present invention has the following advantages:

[0044] 1. The battery charging strategy proposed in the present invention sets a reasonable charging current according to the battery capacity to accurately control the charging current, thereby improving the charging efficiency of the battery and reducing damage to the battery.

[0045] 2. When the power of the charger is less than the vehicle demand during charging of the electric vehicle proposed by the present invention, the battery box of the battery swap station can provide energy replenishment for the electric vehicle safely and effectively, thereby improving the charging utilization rate of the battery swap station.

[0046] 3. The present invention proposes that when the grid load reaches a peak, the charging and swapping containers can be used as large-scale energy storage to provide electricity to the grid; the charging and swapping containers can not only provide charging and swapping services for electric vehicles, but also provide electricity to the grid according to grid dispatch, which can more effectively improve the utilization rate and economic benefits of the charging and swapping containers. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic diagram of the structure of the battery replacement device in the charging, discharging and battery replacement method for electric vehicles and the battery replacement device of the present invention;

[0048] Figure 2 It is a schematic diagram of the arrangement of charging and discharging containers in the charging and discharging method and the battery replacement device for electric vehicles of the present invention;

[0049] Figure 3 A schematic diagram of the flow of charging and discharging energy in the charging and discharging power exchange method and power exchange device for electric vehicles according to the present invention;

[0050] Figure 4 It is a schematic diagram of the charging control flow in the charging and discharging battery replacement method and the battery replacement device for electric vehicles of the present invention;

[0051] Figure 5 A curve diagram of the battery charging current in the charging and discharging battery replacement method and the battery replacement device for electric vehicles according to the present invention;

[0052] Figure 6 This is an experimental diagram of battery charging in the charging and discharging battery replacement method and battery replacement device for electric vehicles according to the present invention. DETAILED DESCRIPTION

[0053] In order to fully describe the technical content, objectives and effects of the present invention, the following will be described in detail with reference to the accompanying drawings.

[0054] Charging and discharging devices for electric vehicles, such as Figure 1 As shown, it includes a high-voltage AC distribution unit, a charging and swapping container, and a charging pile. The high-voltage AC distribution unit supplies power to the charging and swapping container and has a bidirectional function. At the same time, the high-voltage AC distribution unit uses an isolation transformer with two incoming lines and multiple outputs to reduce the voltage, and the two incoming lines are used as backup for each other. The output end of the high-voltage AC distribution unit is connected to the input end of the charging and swapping container, and the output end of the charging and swapping container is connected to the charging pile.

[0055] like Figure 2 As shown, the charging and swapping container includes a battery swapping unit, a charging and discharging unit and a charging and discharging battery swapping station monitoring unit; the battery swapping unit includes a battery swapping device, a battery box station and a battery swapping station. The battery swapping device is located between the battery box station and the battery swapping station. The battery swapping device removes the battery box of the electric vehicle at the battery swapping station and replaces the battery box at the battery box station to the electric vehicle. The battery swapping method is fully automatic.

[0056] The charging and discharging unit consists of multiple high-power bidirectional AC / DC charging and discharging units and AC / DC controllers, such as Figure 3 As shown, the AC / DC charging and discharging unit converts the AC power of the grid into DC power and outputs it to the battery box and charging pile at the battery box station to charge, or converts the DC power fed back by the battery box and charging pile at the battery box station into AC power to reversely charge the grid. The charging and discharging process cannot be carried out at the same time; the AC / DC controller controls the charging output and discharge input power of the AC / DC charging and discharging unit. The charging pile is installed on the side wall of the charging and swapping container, and has the function of charging electric vehicles and reverse discharge.

[0057] The first end of the AC / DC controller is connected to the input end of the AC / DC charging and discharging unit, the output end of the AC / DC charging and discharging unit is connected to the battery box station, the second end of the AC / DC controller is connected to the charging pile through the charging pile controller, each AC / DC charging and discharging unit corresponds to multiple battery box stations and charging piles, the AC / DC charging and discharging unit controls the charging of the corresponding multiple battery box stations and charging piles through the control switch Ki of the AC / DC controller, and the AC / DC charging and discharging unit provides charging for the battery box and charging pile of the battery box station.

[0058] The charging and discharging method for electric vehicles, such as Figure 3 and 4 As shown, the specific implementation steps are as follows:

[0059] S1, AC / DC controller according to the charging demand of the electric vehicle battery box S 1 and the charging demand S of the charging pile 2, monitor the changes in charging demand in real time, and provide timing according to the charging needs of electric vehicle battery boxes and charging piles.

[0060] S2. On the basis of the optimal charging curve in step S1, the charging capacity threshold of the AC / DC charging and discharging unit, the charging demand threshold of the charging pile and the charging demand threshold of the electric vehicle battery box are set respectively. When the charging pile and the battery box require charging at the same time, the charging controller compares the total capacity S of the charging demand of the charging pile and the battery box with the charging capacity S of the AC / DC charging and discharging unit. 0 , and complete the corresponding operations.

[0061] S3. When the charging pile and the battery box require charging at different times, the AC / DC controller compares the total capacity S of the charging pile and the battery box with the charging capacity S of the AC / DC charging and discharging unit. 0 , and complete the corresponding operations.

[0062] S31. If the AC / DC controller detects that only the battery box needs to be charged, the AC / DC controller compares the charging capacity S of the AC / DC charging and discharging unit. 0 and the battery box charging requirement S 1 , and complete the corresponding operations.

[0063] S32: If the AC / DC controller detects that only the battery box of the electric vehicle needs to be charged, the AC / DC controller compares the charging capacity S of the AC / DC charging and discharging unit. 0 and the charging demand S of the charging pile 2 , and complete the corresponding operations.

[0064] S33: If the AC / DC controller does not require charging at the same time, when the AC / DC controller detects that a charging demand from a battery box or a charging pile is added, execute step S2.

[0065] S4. According to the battery voltage and current fed back in real time by the electric vehicle battery box management system and the battery swap unit battery box management system, adjust the output voltage and current of the charging pile and complete charging.

[0066] Furthermore, the method of providing a timing sequence according to the charging requirements of the electric vehicle battery box and the charging pile in step S1 includes:

[0067] S11. The best charging curve of the current in the battery box or charging pile: According to Maas's law, the expression of the best charging curve is as follows:

[0068] I t =I 0 e -at (1)

[0069] Among them, I 0Initial current when charging the electric vehicle battery box, I t is the charging current at a certain moment, t is the charging time, and a is the charging acceptance rate.

[0070] According to the battery charging in the battery box or charging pile, the specific expression of the battery capacity Q is as follows:

[0071]

[0072] According to formulas (1) and (2), the expression of the optimal charging curve at a certain moment in the battery box or charging pile is as follows:

[0073] I t =I 0 -aQ. (3)

[0074] S12. Optimal charging curve of the voltage in the battery box or charging pile: According to the battery characteristics and charging requirements, the PNGV (the Partnership for a New Generation of Vehicles) equivalent model of the battery is constructed. The specific expression is as follows:

[0075]

[0076] S t =I t *U t (5)

[0077] Among them, U 0 The initial voltage when charging the electric vehicle battery box, U oc is the open circuit voltage of the battery, U t is the voltage at any time t during the charging process, I t is the current at any time t during the charging process, C Q is the capacitance value of the battery open circuit voltage change, C e is the polarization capacitance value, R 0 is the ohmic internal resistance of the battery, R e is the polarization internal resistance, U e For U T is the rated voltage of the battery box of the electric vehicle, S t Charging energy for electric vehicle battery boxes.

[0078] Preferably, the comparison in step S2 is the sum of the charging requirements of the charging pile and the battery box and the charging capacity S of the AC / DC charging and discharging unit. 0 , and complete the specific process of the corresponding operation as follows:

[0079] S21, if S 0 ≥S 1 +S 2, execute step S4.

[0080] S22, if S 0 <S 1 +S 2 When S is used, the battery box charging demand is reduced. 2 The output of S 0 =S 1 +S 2 , execute step S4.

[0081] S23, if S 0 <S 1 When the battery box is stopped from charging, the battery box is controlled to charge the charging pile through the AC / DC charging and discharging unit, so that S 0 +S 2 =S 1 , execute step S4.

[0082] Specifically, the specific operation steps of step S31 include:

[0083] S311, if S 0 ≥S 1 , then execute step S4.

[0084] S312, if S 0 <S 1 When the battery box stops charging, the AC / DC charging and discharging unit controls the battery box to charge the charging pile, so that S 0 +S 2 =S 1 , execute step S4.

[0085] Specifically, the specific operation steps of step S32 include:

[0086] S321, if S 0 ≥S 2 , then execute step S4.

[0087] S322, if S 0 <S 2 When the AC / DC charging and discharging unit is used to control the battery box to charge the charging pile, S 0 +S 2 =S 1 , execute step S4.

[0088] Furthermore, the specific process of the voltage and current of the battery in step S4 according to the real-time feedback of the electric vehicle battery box management system and the battery box management system of the battery replacement unit is as follows:

[0089] S41, the AC / DC controller adjusts the output of the AC / DC charge and discharge unit according to the charging demand voltage and current fed back in real time by the electric vehicle battery box management system, until the output voltage is consistent with the voltage of the battery in the charging pile, the output current is 0, the AC / DC charge and discharge unit stops outputting, starts the standby mode, and completes charging.

[0090] S42, the AC / DC controller adjusts the output of the AC / DC charge and discharge unit according to the charging demand voltage and current fed back in real time by the battery box management system of the battery swap unit, until the output voltage is consistent with the voltage of the electric vehicle battery box and the output current is 0, the AC / DC charge and discharge unit stops outputting, starts the standby mode, and completes charging.

[0091] In a preferred embodiment of the present invention, step S23, step S312 or step S322 also includes another charging form, namely, powering the battery of the charging pile or the electric vehicle battery box by closing an idle AC / DC charging and discharging unit or an AC / DC charging and discharging unit with redundant capacity.

[0092] In the charging, discharging and battery swapping method for electric vehicles, not only can conventional charging operations such as charging piles charging battery boxes, charging piles charging electric vehicles through charging pile battery management systems and battery boxes charging electric vehicles through electric vehicle battery box management systems be realized, but also the battery boxes of electric vehicles are discharged to the power grid through high-voltage AC distribution units, solving the problem that when the power grid load reaches its peak, the charging and battery swapping containers provide power to the power grid as large-scale energy storage services, and provide power to the power grid according to power grid dispatch, effectively improving the utilization rate and economic benefits of charging and swapping stations.

[0093] The following is a further description of a charging and discharging battery replacement method and a battery replacement device for an electric vehicle according to the present invention in combination with an embodiment:

[0094] The specific implementation process of the charging and discharging method of the present invention is as follows:

[0095] S1, AC / DC controller according to the charging and discharging characteristics of the electric vehicle battery box charging demand S 1 and the charging demand S of the charging pile 2 , monitor the changes in charging demand in real time, and provide priority charging timing according to the charging needs of electric vehicle battery boxes and charging piles.

[0096] S2. On the basis of the optimal charging curve in step S1, and based on the capacity of the existing electric vehicle battery box being 60kWh, and in order to better extend the service life of the electric vehicle battery box, the current charging and swapping unit in the charging and swapping container takes 1.5 hours to charge the battery box, while the electric vehicle battery box is generally charged in the charging pile within 1 hour. Therefore, the charging capacity threshold of the AC / DC charging and discharging unit is set to 60kW, the charging demand threshold of the charging pile is set to 60kW, and the charging demand threshold of the electric vehicle battery box is set to 120kW.

[0097] When the charging pile and the battery box need to be charged at the same time, the charging controller receives the request for charging the battery box and the request for charging the electric vehicle, and compares the total capacity S of the charging pile and the battery box and the charging capacity S of the AC / DC charging unit. 0 , and make corresponding judgments.

[0098] That is, all AC / DC charging and discharging units are in working condition. The charging demand of an existing electric vehicle battery box is 80kW. The AC / DC charging and discharging unit corresponding to the charging pile can only provide 60kW of power output for the electric vehicle. Other AC / DC charging and discharging units cannot provide excess power. The AC / DC controller controls the AC / DC charging and discharging unit to reduce the output to the battery box until the battery box provides the remaining 20kW of power for the electric vehicle.

[0099] S3. When the charging pile and the battery box require charging at different times, the AC / DC controller compares the total capacity S of the charging pile and the battery box with the charging capacity S of the AC / DC charging and discharging unit. 0 , and complete the corresponding operations.

[0100] S31. If the AC / DC controller detects that only the battery box needs to be charged, the AC / DC controller compares the charging capacity S of the AC / DC charging and discharging unit. 0 and the battery box charging requirement S 1 , and complete the corresponding operations.

[0101] S32: If the AC / DC controller detects that only the battery box of the electric vehicle needs to be charged, the AC / DC controller compares the charging capacity S of the AC / DC charging and discharging unit. 0 and the charging demand S of the charging pile 2 , and complete the corresponding operations.

[0102] S33: If the AC / DC controller does not require charging at the same time, when the AC / DC controller detects that a charging demand from a battery box or a charging pile is added, execute step S2.

[0103] That is, all AC / DC charging and discharging units are in working condition. The charging demand of an electric vehicle battery box is 60kW, and the AC / DC charging and discharging unit corresponding to the charging pile provides 60kW power output for the electric vehicle.

[0104] S4. According to the battery voltage and current fed back in real time by the electric vehicle battery box management system and the battery box management system of the battery swap unit, the output voltage and current of the charging pile are adjusted to make the battery charging current closer to the optimal charging curve of the battery, such as Figure 5 and Figure 6 As shown, the corresponding charging is completed.

[0105] Through the above embodiments, it can be seen that the battery capacity charging method of the present invention better highlights: the charging time is shorter than others and the charging speed is the fastest; the voltage at the battery end and the SOC at the end of charging are relatively high, and the battery charging efficiency is more sufficient.

[0106] The charging and discharging method of the present invention utilizes idle batteries to eliminate peak loads and fill valley loads. When necessary, it can reversely send electricity to the power grid to reduce operating costs. When the electricity price is high, the idle battery power is used to charge the vehicle. When the capacity of the charging and discharging device is limited, the load on the power grid is not increased, and the battery power is used as a supplement to meet the charging demand as much as possible. The output power of the charging pile is reasonably configured to improve the utilization efficiency of the charging pile. The charging pile can charge the electric vehicle and the battery box at the same time.

[0107] In summary, when the grid load is at its peak, the charging and swapping containers of the present invention can be used as large-scale energy storage to provide electricity to the grid; the charging and swapping containers can not only provide charging and swapping services for electric vehicles, but also provide electricity to the grid according to the grid dispatch, which can more effectively improve the utilization rate and economic benefits of the charging and swapping containers.

[0108] The embodiments described above are only descriptions of the preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A charging and discharging method for an electric vehicle, characterized in that: The specific implementation steps are as follows: S1, AC / DC controller monitors the charging demand changes in real time according to the charging demand S1 of the electric vehicle battery box and the charging demand S2 of the charging pile, and provides timing according to the charging demand of the electric vehicle battery box and the charging pile: S11. The best charging curve of the current in the battery box or charging pile: According to Maas's law, the expression of the best charging curve is as follows: I t =I0e -at (1) Among them, I0 is the initial current when the electric vehicle battery box is charged, I t is the charging current at a certain moment, t is the charging time, and a is the charging acceptance rate; According to the battery charging in the battery box or charging pile, the specific expression of the battery capacity Q is as follows: According to formulas (1) and (2), the expression of the optimal charging curve at a certain moment in the battery box or charging pile is as follows: I t =I0-aQ; (3) S12. Optimal charging curve of the voltage in the battery box or charging pile: According to the battery characteristics and charging requirements, the PNGV equivalent model of the battery is constructed. The specific expression is as follows: WITH t =I t *IN t (5) Among them, U0 is the initial voltage of the electric vehicle battery box when charging, U oc is the open circuit voltage of the battery, I0 is the initial current when the electric vehicle battery box is charged, and U t is the voltage at any time t during the charging process, I t is the current at any time t during the charging process, C Q is the capacitance value of the battery open circuit voltage change, C e is the polarization capacitance value, R0 is the ohmic internal resistance of the battery, R e is the polarization internal resistance, U e For U T is the rated voltage of the battery box of the electric vehicle, S t Charging energy for electric vehicle battery boxes; S2. On the basis of the optimal charging curve in step S1, the charging capacity threshold of the AC / DC charging and discharging unit, the charging demand threshold of the charging pile and the charging demand threshold of the electric vehicle battery box are set respectively. When the charging pile and the battery box require charging at the same time, the charging controller compares the total capacity S of the charging demand of the charging pile and the battery box with the charging capacity S0 of the AC / DC charging and discharging unit, and completes the corresponding operation: S21, if S0≥S1+S2, execute step S4; S22, if S0<S1+S2, reduce the output of the battery box charging demand S2, so that S0=S1+S2, and execute step S4; S23, if S0<S1, stop charging the battery box, and control the battery box to charge the charging pile through the AC / DC charging and discharging unit, so that S0+S2=S1, and execute step S4; S3. When the charging pile and the battery box require charging at different times, the AC / DC controller compares the total capacity S of the charging pile and the battery box with the charging capacity S0 of the AC / DC charging and discharging unit, and completes the corresponding operation: S31. If the AC / DC controller detects that only the battery box needs to be charged, the AC / DC controller compares the charging capacity S0 of the AC / DC charging and discharging unit and the charging demand S1 of the battery box, and completes the corresponding operation; S32. If the AC / DC controller detects that only the battery box of the electric vehicle needs to be charged, the AC / DC controller compares the charging capacity S0 of the AC / DC charging and discharging unit with the charging demand S2 of the charging pile, and completes the corresponding operation; S33, if the AC / DC controller does not require charging at the same time, when the AC / DC controller detects that a battery box or a charging pile has added a charging demand, execute step S2; S4. According to the battery voltage and current fed back in real time by the battery box management system of the electric vehicle and the battery box management system of the battery swap unit, the output voltage and current of the charging pile are adjusted to complete the charging.

2. The charging and discharging method for electric vehicles according to claim 1, characterized in that: In step S23, step S312 or step S322, another charging form is also included, that is, powering the battery of the charging pile or the electric vehicle battery box by closing an idle AC / DC charging and discharging unit or an AC / DC charging and discharging unit with redundant capacity.

3. The charging and discharging method for electric vehicles according to claim 1, characterized in that: The specific steps of step S31 include: S311, if S0≥S1, execute step S4; S312, if S0<S1, stop charging the battery box, and control the battery box to charge the charging pile through the AC / DC charging and discharging unit, so that S0+S2=S1, and execute step S4.

4. The charging and discharging method for electric vehicles according to claim 1, characterized in that: The specific steps of step S32 include: S321, if S0≥S2, execute step S4; S322: If S0<S2, the battery box is controlled by the AC / DC charging and discharging unit to charge the charging pile, so that S0+S2=S1, and step S4 is executed.

5. The charging and discharging method for electric vehicles according to claim 1, characterized in that: The specific steps of step S4 include: S41, the AC / DC controller adjusts the output of the AC / DC charging and discharging unit according to the charging demand voltage and current fed back in real time by the electric vehicle battery box management system, until the output voltage is consistent with the voltage of the battery in the charging pile, the output current is 0, the AC / DC charging and discharging unit stops outputting, starts the standby mode, and completes charging; S42, the AC / DC controller adjusts the output of the AC / DC charge and discharge unit according to the charging demand voltage and current fed back in real time by the battery box management system of the battery swap unit, until the output voltage is consistent with the voltage of the electric vehicle battery box and the output current is 0, the AC / DC charge and discharge unit stops outputting, starts the standby mode, and completes charging.

6. A charging and discharging device for electric vehicles according to the method of any one of claims 1 to 5, characterized in that: It includes a high-voltage AC power distribution unit, a charging and swapping container and a charging pile, the output end of the high-voltage AC power distribution unit is connected to the input end of the charging and swapping container, and the output end of the charging and swapping container is connected to the charging pile; the charging and swapping container includes a battery swapping unit, a charging and discharging unit and a charging and discharging station monitoring unit; the battery swapping unit includes a battery swapping device, a battery box station and a battery swapping station, and the battery swapping device is located between the battery box station and the battery swapping station; the charging and discharging unit includes an AC / DC charging and discharging unit and an AC / DC controller, the AC / DC controller controls the charging output and discharge input power of the AC / DC charging and discharging unit, the first end of the AC / DC controller is connected to the input end of the AC / DC charging and discharging unit, the output end of the AC / DC charging and discharging unit is connected to the battery box station, the second end of the AC / DC controller is connected to the charging pile through a charging pile controller, and the AC / DC charging and discharging unit controls the charging of the corresponding battery box station and the charging pile through the control switch Ki of the AC / DC controller.

7. A charging and discharging device for an electric vehicle according to claim 6, characterized in that: The AC / DC controller is connected to a first end of the charging pile controller via a CAN line, and a second end of the charging pile controller is connected to the charging pile via a CAN line.

8. A charging and discharging device for an electric vehicle according to claim 6, characterized in that: The number of the AC / DC charging and discharging units, the number of the battery box stations and the number of the charging piles are equal, and each AC / DC charging and discharging unit corresponds to a battery box station and a charging pile.

9. A charging and discharging device for an electric vehicle according to claim 6 or 7, characterized in that: The number of the charging pile controller is one, and a plurality of the charging piles are connected in parallel to the output end of the charging pile controller.

10. A charging and discharging device for an electric vehicle according to claim 6, characterized in that: The AC / DC charging and discharging unit converts the AC power of the power grid into DC power and outputs it to the battery box and charging pile at the battery box station for charging, or converts the DC power fed back from the battery box and charging pile at the battery box station into AC power to reversely charge the power grid. The charging process and the discharging process cannot be carried out at the same time.

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