Power battery charging method, charging device, and charging system

Abstract

An embodiment of the present application provides a charging method and a charging device for a power battery, which can improve the performance of the charging device. The charging method is used in the charging device. The charging device includes N energy storage units connected in series, each energy storage unit including an energy storage battery and a first DC / DC converter connected to the energy storage battery. Each charging cycle of the charging device includes a step of charging the power battery and a step of discharging the power battery to the N energy storage units. The charging method includes, in the discharging step, obtaining a current voltage of the energy storage battery in each energy storage unit, determining a first voltage output by the first DC / DC converter in each energy storage unit based on the current voltage of the energy storage battery in each energy storage unit, where the first voltage is inversely proportional to the current voltage of the energy storage battery, and transmitting the first voltage to the first DC / DC converter, so that the energy storage battery receives an amount of power released by the power battery according to the first voltage via the first DC / DC converter.

Description

[Technical field]

[0001] The present application relates to the field of battery technology, and in particular to a charging method, a charging device and a charging system for a power battery. [Background technology]

[0002] With the urgent demand for non-renewable energy consumption and environmental protection, new energy electric vehicles using rechargeable batteries as a power source are rapidly developing. Currently, the method of alternately charging and discharging the power battery is adopted to realize fast charging of the power battery, and an energy storage unit can be installed to receive the amount of power released by the power battery during discharging. However, due to factors such as the capacity of the energy storage unit, the charging efficiency of the power battery cannot be further improved. Summary of the Invention

[0003] The embodiments of the present application provide a charging method, a charging device, and a charging system for a power battery that can improve charging efficiency.

[0004] According to a first aspect, the present application provides a method for charging a power battery used in a charging device, the charging device includes N energy storage units connected in series, where each energy storage unit includes an energy storage battery and a first DC / DC converter connected with the energy storage battery, each charging cycle of the charging device includes a step of charging the power battery and a step of discharging the power battery to the N energy storage units, where N is a positive integer greater than 1. The charging method includes, in a discharging step, obtaining a current voltage of the energy storage battery in each energy storage unit; determining a first voltage output by a first DC / DC converter in each energy storage unit based on the current voltage of the energy storage battery in each energy storage unit, where the first voltage output by the first DC / DC converter in each energy storage unit is inversely proportional to the current voltage of the energy storage battery in each energy storage unit; and sending a first control signal to the first DC / DC converter in each energy storage unit, where the first control signal is used to control the first DC / DC converter to output a first voltage, so that the energy storage battery in each energy storage unit receives an amount of power released by the power battery according to the first voltage through the first DC / DC converter in each energy storage unit.

[0005] In the embodiment of the present application, the power battery is fast-charged based on the alternate charging and discharging method, and the charging device includes a plurality of energy storage units connected in series, and each energy storage unit includes an energy storage battery and a first DC / DC converter connected thereto. Therefore, the output voltage of each first DC / DC converter can be controlled to adjust the amount of power discharged by the power battery to each energy storage unit, for example, the output voltage of the first DC / DC converter of each energy storage unit is adjusted to be inversely proportional to the current voltage of the energy storage battery, so that the amount of power that each energy storage unit can withstand is matched to the current amount of power, and the problem of energy mismatch between each energy storage unit is avoided, thereby realizing full utilization of the capacity of each energy storage unit, and each energy storage unit can more effectively receive the amount of power released by the power battery, and improving the charging efficiency of the power battery.

[0006] In one possible embodiment, the charging method further includes, in the charging step, obtaining a current voltage of the energy storage battery in each energy storage unit; determining a second voltage output by the first DC / DC converter in each energy storage unit based on the current voltage of the energy storage battery in each energy storage unit, wherein the second voltage output by the first DC / DC converter in each energy storage unit is proportional to the current voltage of the energy storage battery in each energy storage unit; and sending a second control signal to the first DC / DC converter in each energy storage unit, wherein the second control signal is used to control the first DC / DC converter to output the second voltage, so that the energy storage battery in each energy storage unit charges the power battery according to the second voltage through the first DC / DC converter in each energy storage unit.

[0007] In this embodiment, during the stage of charging the power battery, the output voltage of the first DC / DC converter of each energy storage unit is adjusted to be proportional to the current voltage of the energy storage battery, so that the amount of power provided by each energy storage unit can be matched to its current amount of power, and the capacity of each energy storage battery can be fully utilized, thereby improving the charging efficiency of the power battery.

[0008] In one possible embodiment, the charging device further includes an isolation unit, which is connected between the N energy storage units and the power battery, and which includes M second DC / DC converters and a switch module connected between the M second DC / DC converters, where M is a positive integer greater than or equal to 2.

[0009] In one possible embodiment, the charging method further includes: the control switch module connects the M second DC / DC converters in series, thereby making the voltage output by the isolation unit to the power battery equal to M times the voltage output by the N energy storage units; or the control switch module connects the M second DC / DC converters in parallel, thereby making the current output by the isolation unit to the power battery equal to M times the current output by the N energy storage units.

[0010] The above embodiment further provides an isolation unit connected between the N energy storage units and the power battery, the isolation unit including M second DC / DC converters and a switch module connected between the M second DC / DC converters. The switch module can be controlled to change the connection manner between the M second DC / DC converters to adjust the output voltage of the isolation unit. When the switch module of the isolation unit is controlled to connect the M second DC / DC converters in series, the power battery can be charged at a high voltage by the charging device, and when the switch module of the isolation unit is controlled to connect the M second DC / DC converters in parallel, the power battery can be charged at a high current by the charging device.

[0011] In one possible embodiment, the charging device further includes an AC / DC converter connected between the power battery and the AC power source, and the charging method further includes sending a third control signal to the AC / DC converter, the third control signal being used to control a voltage output by the AC / DC converter to be equal to a charging voltage of the power battery, so that the AC power source charges the power battery according to the charging voltage through the AC / DC converter.

[0012] In one possible embodiment, the charging method further includes sending a fourth control signal to the AC / DC converter, the fourth control signal being used to control the voltage output by the AC / DC converter to be equal to the discharge voltage of the power battery, thereby causing the power battery to discharge to an AC power source via the AC / DC converter according to the discharge voltage.

[0013] In the above embodiment, an AC / DC converter is further connected between the power battery and the AC power source. This AC / DC converter can not only convert the AC power output by the AC power source into stable DC power to charge the power battery, but also convert the DC power output by the power battery into AC power during the discharging stage of the power battery, thereby releasing the power of the power battery to the AC power source, and realize the power battery to simultaneously discharge to the energy storage unit and the AC power source, thereby shortening the time length of the discharging stage of the power battery and further improving the charging efficiency.

[0014] According to a second aspect, the present application provides a charging device for a power battery, the charging device includes N energy storage units connected in series, and a control module, where each energy storage unit includes an energy storage battery and a first DC / DC converter connected with the energy storage battery. Each charging cycle of the charging device includes a step of charging the power battery and a step of discharging the power battery to the N energy storage units, where N is a positive integer greater than 1. The control module is used for, in a discharging step, obtaining a current voltage of the energy storage battery in each energy storage unit; determining a first voltage output by the first DC / DC converter in each energy storage unit based on the current voltage of the energy storage battery in each energy storage unit, where the first voltage output by the first DC / DC converter in each energy storage unit is inversely proportional to the current voltage of the energy storage battery in each energy storage unit; and sending a first control signal to the first DC / DC converter in each energy storage unit, where the first control signal is used to control the first DC / DC converter to output a first voltage, so that the energy storage battery in each energy storage unit receives an amount of power released by the power battery according to the first voltage through the first DC / DC converter in each energy storage unit.

[0015] The charging device of the embodiment of the present application realizes rapid charging of the power battery based on an alternating charging and discharging manner, and the charging device includes a plurality of energy storage units connected in series, and each energy storage unit includes an energy storage battery and a first DC / DC converter connected thereto, so that the amount of power discharged by the power battery to each energy storage unit can be adjusted by controlling the output voltage of each first DC / DC converter, for example, the output voltage of the first DC / DC converter of each energy storage unit is adjusted to be inversely proportional to the current voltage of the energy storage battery, so that the amount of power that each energy storage unit can withstand is matched to the current amount of power, and the problem of energy mismatch between each energy storage unit is avoided, thereby realizing full utilization of the capacity of each energy storage unit, and each energy storage unit can more effectively receive the amount of power released by the power battery, and improving the charging efficiency of the power battery.

[0016] In one possible embodiment, the control module is further used for, in the charging step, obtaining a current voltage of the energy storage battery in each energy storage unit; determining a second voltage output by the first DC / DC converter in each energy storage unit based on the current voltage of the energy storage battery in each energy storage unit, wherein the second voltage output by the first DC / DC converter in each energy storage unit is proportional to the current voltage of the energy storage battery in each energy storage unit; and sending a second control signal to the first DC / DC converter in each energy storage unit, wherein the second control signal is used to control the first DC / DC converter to output the second voltage, so that the energy storage battery in each energy storage unit charges the power battery according to the second voltage through the first DC / DC converter in each energy storage unit.

[0017] In this embodiment, during the stage of charging the power battery, the output voltage of the first DC / DC converter of each energy storage unit is adjusted to be proportional to the current voltage of the energy storage battery, so that the amount of power provided by each energy storage unit can be matched to its current amount of power, and the capacity of each energy storage battery can be fully utilized, thereby improving the charging efficiency of the power battery.

[0018] In one possible embodiment, the charging device further includes an isolation unit connected between the N energy storage units and the power battery. The isolation unit includes M second DC / DC converters and a switch module connected between the M second DC / DC converters, where M is a positive integer equal to or greater than 2. The control module is further used for controlling the control switch module to connect the M second DC / DC converters in series, so that the voltage output by the isolation unit to the power battery is equal to M times the voltage output by the N energy storage units, or for controlling the control switch module to connect the M second DC / DC converters in parallel, so that the current output by the isolation unit to the power battery is equal to M times the current output by the N energy storage units.

[0019] The above embodiment provides an isolation unit connected between N energy storage units and a power battery, the isolation unit including M second DC / DC converters and a switch module connected between the M second DC / DC converters. The switch module can be controlled to change the connection manner between the M second DC / DC converters to adjust the output voltage of the isolation unit. When the switch module of the isolation unit is controlled to connect the M second DC / DC converters in series, a high voltage charging to the power battery can be realized, and when the switch module of the isolation unit is controlled to connect the M second DC / DC converters in parallel, a high current charging to the power battery can be realized.

[0020] In one possible embodiment, the charging device further includes an AC / DC converter connected between the power battery and an AC power source, and the control module is further used for sending a third control signal to the AC / DC converter, and the third control signal is used for controlling the voltage output by the AC / DC converter to be equal to the charging voltage of the power battery, so that the AC power source charges the power battery according to the charging voltage through the AC / DC converter.

[0021] In one possible embodiment, the control module is further used for sending a fourth control signal to the AC / DC converter, and the fourth control signal is used for controlling the voltage output by the AC / DC converter to be equal to the discharge voltage of the power battery, so that the power battery is discharged to an AC power source via the AC / DC converter according to the discharge voltage.

[0022] In the above embodiment, an AC / DC converter is further connected between the power battery and the AC power source. This AC / DC converter can not only convert the AC power output by the AC power source into stable DC power to charge the power battery, but also convert the DC power output by the power battery into AC power during the discharging stage of the power battery, thereby releasing the power of the power battery to the AC power source, and realize the power battery to simultaneously discharge to the energy storage unit and the AC power source, thereby shortening the time length of the discharging stage of the power battery and further improving the charging efficiency.

[0023] According to a third aspect, the present application provides an EMS including a processor for carrying out the method of any one of the possible embodiments of the first and second aspects as described above.

[0024] According to a fourth aspect, an embodiment of the present application provides a charging system, the charging system including a power battery and a charging device in the second aspect or any one of the possible embodiments of the second aspect, the charging device being used to charge the power battery, wherein each charging cycle includes a step of charging the power battery and a step of discharging the power battery.

[0025] In order to more clearly explain the technical solutions of the embodiments of the present application, the following briefly introduces the drawings that need to be used in the embodiments of the present application. It is obvious that the drawings described below are only some embodiments of the present application, and those skilled in the art can also obtain other drawings based on the drawings without exerting creative efforts. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a structural schematic diagram of a charging system according to an embodiment of the present application. [Diagram 2] FIG. 2 is a charging cycle schematic diagram of one embodiment of the present application. [Diagram 3] FIG. 2 is a structural schematic diagram of a charging device according to an embodiment of the present application; [Figure 4] 2 is a flowchart of a charging method according to an embodiment of the present application. [Diagram 5] FIG. 2 is a structural schematic diagram of a charging device according to another embodiment of the present application; [Figure 6] FIG. 2 is a structural schematic diagram of a charging device according to another embodiment of the present application; [Figure 7] 5 is a flowchart of a specific implementation of the charging method shown in FIG. 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] The following describes the embodiments of the present application in more detail in conjunction with the drawings and examples. The detailed description of the embodiments and the drawings are for illustrative purposes only to explain the principles of the present application, but are not intended to limit the scope of the present application, i.e., the present application is not limited to the described embodiments.

[0028] In the description of this application, it should be explained that, unless otherwise specified, the meaning of "plurality" is two or more, and the orientation or positional relationship indicated by the terms "up", "down", "left", "right", "inside", "outside", etc., is merely for convenience and simplification of the description of this application, and does not indicate or imply that the device or element referred to has a particular orientation, must be configured and operated in a particular orientation, and should not be understood as a limitation on this application. In addition, the terms "first", "second", "third", etc. are used for descriptive purposes only, and should not be understood as indicating or implying relative importance.

[0029] The directions appearing in the following description are all directions shown in the drawings, and do not limit the specific structure of the present application. In the description of the present application, it should be further explained that unless otherwise clearly specified or limited, the terms "attached", "connected" and "connected" should be understood in a broad sense, for example, may be fixedly connected, detachably connected, or integrally connected, may be directly connected, or may be indirectly connected through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the present application according to the specific situation.

[0030] In the new energy field, the power battery can be the main power source of the power consumption device, such as a vehicle, a ship, or an aerospace aircraft, while the energy storage battery can be the charging source of the power consumption device, and the importance of both goes without saying. For example and not for limitation, in some application scenarios, the power battery can be the battery in the power consumption device, and the energy storage battery can be the battery in the charging device.

[0031] FIG. 1 shows a structural schematic diagram of a charging system applied to an embodiment of the present application.

[0032] 1, the charging system 10 may include a charging device 100 and a battery system 200. Optionally, the battery system 200 may be a battery system in an electric vehicle (including a pure electric vehicle and a plug-in hybrid electric vehicle) or a battery system in other application scenarios.

[0033] Optionally, at least one battery pack may be installed in the battery system 200, and the at least one battery pack may be collectively referred to as a power battery 210. In terms of the type of battery, the power battery 210 may be any type of battery, including, but not limited to, a lithium ion battery, a lithium metal battery, a lithium sulfur battery, a lead acid battery, a nickel cadmium battery, a nickel hydrogen battery, or a lithium air battery. In terms of the size of the battery, the power battery 210 in the embodiment of the present application may be a battery core / cell, a battery module, or a battery pack, and the battery module or the battery pack may be formed by connecting a plurality of batteries in series and parallel. In the embodiment of the present application, there is no specific limitation on the type and size of the power battery 210.

[0034] In order to intelligently manage and maintain the power battery 210, prevent overcharging and overdischarging of the battery, and extend the service life of the battery, the battery system 200 is generally further provided with a battery management system (BMS) 220 for monitoring the state of the power battery 210. Alternatively, the BMS 220 may be integrated with the power battery 210 and installed in the same device or apparatus, or the BMS 220 may be installed outside the power battery 210 as an independent device / apparatus.

[0035] Specifically, the charging device 100 is a device that replenishes electric energy for the power battery 210 in the battery system 200 .

[0036] Optionally, the charging device 100 in the embodiment of the present application may be a normal charging station, a super charging station, a charging station supporting a vehicle to grid (V2G) mode, or a charging device or equipment capable of charging a battery, etc. The embodiment of the present application is not limited to a specific type of the charging device 100 and a specific application scenario.

[0037] Optionally, as shown in FIG. 1 , the charging device 100 may be connected to the power battery 210 via an electric line 300, and connected to the BMS 220 via a communication line 400. Here, the communication line 400 is used to realize information interaction between the charging device 100 and the BMS 220.

[0038] By way of example, the communication line 400 may include, but is not limited to, a control area network (CAN) communication bus or a daisy chain communication bus.

[0039] Optionally, the charging device 100 can communicate with the BMS 220 through the communication line 400, and can also communicate with the BMS 220 through a wireless network. The embodiments of the present application are not specifically limited to the type of communication between the charging device 100 and the BMS 220.

[0040] When the power battery 210 is continuously charged using a conventional charging method, the charging process is limited by the accumulation of lithium ions in the battery negative electrode, and the charging current is also limited, so that the battery cannot be rapidly charged using a sustained large current. In order to rapidly charge the power battery 210, the embodiment of the present application employs a method of alternately charging and discharging the power battery 210 to rapidly charge the power battery 210.

[0041] For example, as shown in Fig. 2, one charging period T includes a stage of charging the power battery 210 and a stage of discharging the power battery 210. Here, in the stage of charging the power battery 210, the charging current is +I1, and in the stage of discharging the power battery 210, the charging current is -I2. After charging the power battery 210 with a large current, the power battery 210 is discharged to release the lithium ions accumulated in the negative electrode of the power battery 210 during charging, thereby avoiding the occurrence of lithium deposition, heat generation, etc. in the power battery 210, and then the power battery 210 is charged again using a large current, thereby realizing rapid charging of the power battery 210.

[0042] The charging device 100 of the embodiment of the present application is provided with an energy storage unit for receiving the amount of power released by the power battery 210 in the discharging stage. The energy storage unit is, for example, an energy storage battery, and the capacity of the energy storage battery directly affects the amount of power that can be released by the power battery 210. In order to improve the capacity of the energy storage battery, the energy storage battery may include a large number of battery cores. When a large number of battery cores are connected in series, if the consistency of the battery cores is relatively poor, the failure of each of the battery cores will lead to the failure of the entire energy storage battery, which directly affects the charging of the power battery 210. In order to improve the reliability of charging, these battery cores are separately installed in multiple energy storage batteries, that is, multiple energy storage batteries can be adopted to simultaneously receive the amount of power released by the power battery 210. In this way, when a battery core in one of the energy storage batteries fails, a certain manner, for example, the energy storage battery can be bypassed, which does not affect the charging of the power battery 210 and can improve the reliability of charging.

[0043] These multiple energy storage batteries can be connected in series, and when the power battery 210 simultaneously discharges to the multiple energy storage batteries connected in series, there may be a difference between the amounts of power of the multiple energy storage batteries, so there is a difference in the voltage across the energy storage batteries. However, if the currents in the multiple energy storage batteries connected in series are equal, the amount of power discharged by the power battery 210 to these multiple energy storage batteries is different. For example, if the voltage across an energy storage battery with a relatively small State of Charge (SOC) is relatively small, the amount of power discharged by the power battery 210 to this energy storage battery within a certain time is small, and if the voltage across an energy storage battery with a relatively large SOC is relatively large, the amount of power discharged by the power battery 210 to this energy storage battery within the same time is large. In this way, there is a possibility that an energy mismatch problem will occur between each energy storage battery. For an energy storage battery with a small SOC, the amount of power received by it is small, and conversely, for an energy storage battery with a large SOC, the amount of power received by it is large, and this energy storage battery is more likely to reach full charge. Since the multiple energy storage batteries follow the bucket principle, when one of the energy storage batteries reaches full charge, the charging of the power battery 210 is terminated accordingly to ensure safety. As can be seen, due to the energy mismatch between the energy storage batteries, the capacity of each energy storage unit cannot be fully utilized, and the charging efficiency of the power battery 210 cannot be further improved.

[0044] To this end, the embodiment of the present application proposes a power battery charging scheme, in which a first DC / DC converter is configured to control the charging voltage and discharging voltage of each energy storage battery, so as to match the amount of power received and discharged by each energy storage battery with its current capacity, to avoid energy mismatch between each energy storage battery, and to improve the charging efficiency of the power battery.

[0045] 3 shows a structural schematic diagram of a charging device 100 in an embodiment of the present application. The charging device 100 may be a charging station or a charger, or may be other types of fixed or mobile charging devices, and is not limited here.

[0046] The charging device 100 may include N energy storage units, such as energy storage unit 110, energy storage unit 120, etc., connected in series, where N is a positive integer greater than 1. Here, each charging cycle of the charging device 100 includes a step of charging the power battery 210 and a step of the power battery 210 discharging to the N energy storage units.

[0047] 3, each energy storage unit includes an energy storage battery and a first DC / DC converter connected to the energy storage battery. For example, the energy storage unit 110 includes an energy storage battery 111 and a first DC / DC converter 112 connected to the energy storage battery 111, and the energy storage unit 120 includes an energy storage battery 121 and a first DC / DC converter 122 connected to the energy storage battery 121.

[0048] Specifically, the energy storage battery in each energy storage unit may be connected in parallel to the first DC side of the first DC / DC converter in this energy storage unit, i.e., the side where port A is located and the side where port B is located, and the two electrodes of the energy storage battery may be connected to port A and port B, respectively. The second DC side of the first DC / DC converter in each energy storage unit is connected in series, i.e., the side where port C is located and the side where port D is located are connected in series. For example, as shown in FIG. 3, the energy storage battery 111 in the energy storage unit 110 is connected in parallel to the first DC side of the first DC / DC converter 112, i.e., the side where port A is located and the side where port B is located of the first DC / DC converter 112, and the energy storage battery 121 in the energy storage unit 120 is connected in parallel to the first DC side of the first DC / DC converter 122, i.e., the side where port A is located and the side where port B is located of the first DC / DC converter 122. The second DC side of the first DC / DC converter 112 is then connected in series between the second DC sides of the first DC / DC converter 122 .

[0049] As can be seen from Fig. 3, the first DC side of the first DC / DC converter is the side for connecting the energy storage battery in the first DC / DC converter, and the second DC side of the first DC / DC converter is the side for connecting the power battery 210 in the first DC / DC converter. It should be noted that when the energy storage battery charges the power battery 210, the first DC side is the input side of the first DC / DC converter, and the second DC side is the output side of the first DC / DC converter; when the power battery 210 discharges the energy storage battery, the first DC side is the output side of the first DC / DC converter, and the second DC side is the input side of the first DC / DC converter.

[0050] Alternatively, the first DC / DC converter may be a voltage-type converter that effectively outputs a fixed voltage after converting the input voltage, and may be implemented as, for example, a step-up / step-down DC / DC converter.

[0051] Alternatively, the N energy storage units may be a single electrical box with N energy storages, and the energy storage batteries in the N energy storage units may be a battery module or a battery pack, and either the battery module or the battery pack may be formed by multiple battery cores connected in series or in parallel.

[0052] In addition, the charging device 100 may further include a control module 160. Here, the control module 160 may be connected to N energy storage units, which are used to control the first DC / DC converters in the N energy storage units to make the power battery 210 discharge to the energy storage unit through the first DC / DC converter, or make the energy storage unit charge the power battery 210 through the first DC / DC converter. The control module 160 may be connected to the BMS 220 of the power battery 210 through a communication line 400 to realize information interaction between the charging device 100 and the BMS 220.

[0053] The control module 160 may be, for example, an energy management system (EMS) controller in a charging station or a charger. Additionally, the control module 160 may further include a secondary source system.

[0054] Optionally, Fig. 4 illustrates a charging method 40 of an embodiment of the present application for charging the power battery 210. The method 40 may be implemented by the above-mentioned control module 160, and may specifically include some or all of the following steps:

[0055] Step 410: During the discharging phase, obtain the current voltage of the energy storage battery in each energy storage unit.

[0056] Step 420: Determine a first voltage output by a first DC / DC converter in each energy storage unit according to the discharge voltage of the power battery 210.

[0057] Here, the first voltage output by the first DC / DC converter in each energy storage unit is inversely proportional to the present voltage of the energy storage battery in each energy storage unit.

[0058] Step 430: Send a first control signal to a first DC / DC converter in each energy storage unit, where the first control signal is used to control the first DC / DC converter to output a first voltage, so that the energy storage battery in each energy storage unit receives an amount of power released by the power battery 210 according to the first voltage through the first DC / DC converter in each energy storage unit.

[0059] In the embodiment of the present application, the power battery 210 is fast-charged based on the alternate charging and discharging method, and the charging device 100 includes N energy storage units connected in series, and each energy storage unit includes an energy storage battery and a first DC / DC converter connected thereto, so that the amount of power discharged by the power battery 210 to each energy storage unit can be adjusted by controlling the output voltage of each first DC / DC converter. When the output voltage of the first DC / DC converter of each energy storage unit is adjusted to be inversely proportional to the current voltage of the energy storage battery, the amount of power that each energy storage unit can withstand can be matched to the current amount of power, and the problem of energy mismatch between each energy storage unit can be avoided, so that the capacity of each energy storage unit can be fully utilized, and each energy storage unit can more effectively receive the amount of power released by the power battery, thereby improving the charging efficiency of the power battery.

[0060] Specifically, when the power battery 210 discharges to the N energy storage units, the control module 160 can receive the discharge voltage sent by the BMS 220, and this discharge voltage is the voltage required for discharging the power battery 210. The control module 160 can simultaneously obtain the current voltage of the energy storage battery in each energy storage unit, and adjust the first voltage output by the first DC / DC converter in each energy storage unit based on the discharge voltage of the power battery 210 and the current voltage of each energy storage battery, so that this first voltage is inversely proportional to the current voltage of the energy storage battery in each energy storage unit. Here, the sum of the voltages of the N energy storage units in the discharging process is equal to this discharge voltage of the power battery 210.

[0061] For example, if the current power of the energy storage battery 111 in the energy storage unit 110 is relatively low, i.e., the SOC is relatively small, the voltage across the energy storage battery 111 is also relatively small, but if the current power of the energy storage battery 121 in the energy storage unit 120 is relatively high, i.e., the SOC is relatively high, the voltage across the energy storage battery 121 is also relatively high. Because the energy storage unit 110 and the energy storage unit 120 are connected in series, the currents when the power battery 210 discharges to the energy storage unit 110 and the energy storage unit 120 are equal. If the voltage and current of the energy storage unit are high when the power battery 210 discharges to the energy storage unit, the amount of power the energy storage unit receives from the power battery 210 is large. In this way, the power battery 210 releases less power to the energy storage battery 111 with a relatively low SOC, but releases more power to the energy storage battery 121 with a relatively high SOC, which causes an energy mismatch between the two energy storage batteries. Because the energy storage battery 121 with a relatively large SOC will soon be fully charged, the charging of the power battery 210 is thereby terminated to ensure safety.

[0062] At this time, when the current voltage of the energy storage battery 111 is relatively small, the control module 160 controls the first DC / DC converter 112 connected to the energy storage battery 111 to output a relatively large first voltage to the energy storage battery 111; correspondingly, when the current voltage of the energy storage battery 121 is relatively large, the control module 160 controls the first DC / DC converter 122 connected to the energy storage battery 121 to output a relatively small first voltage to the energy storage battery 121. In this manner, the amount of power received by the energy storage unit can be matched to the current amount of power, and the energy storage battery 111 with a low current voltage or low current power can obtain more power from the power battery 210, and the energy storage battery 121 with a high current voltage or high current power receives less power from the power battery 210, so that the energy between each energy storage unit is relatively balanced after the power battery 210 is discharged, and the capacity of each energy storage unit can be fully utilized, and the charging efficiency can be improved.

[0063] The above describes how the control module 160 controls the first DC / DC converter during the discharge phase from the power battery 210 to the N energy storage units, and accordingly the control module 160 can control the first DC / DC converter during the charging phase from the N energy storage units to the power battery 210 to achieve a better balance of energy between the N energy storage units.

[0064] It should be understood that in the embodiment of the present application, only the AC power source 150, i.e., the grid, may charge the power battery 210, or the N energy storage units and the AC power source 150 may jointly charge the power battery 210. Optionally, as shown in Fig. 5, the charging device 100 further includes an AC / DC converter 140 connected between the power battery 210 and the AC power source 150, and when charging the power battery 210, the AC power output by the AC power source 150 is converted into stable DC power via the AC / DC converter 140 to charge the power battery 210.

[0065] Specifically, when the AC power source 150 charges the power battery 210, the control module 160 can send a third control signal to the AC / DC converter 140, and this third control signal is used to control the voltage output by the AC / DC converter 140 to be equal to the charging voltage of the power battery 210, so that the AC power source 150 charges the power battery 210 according to this charging voltage via the AC / DC converter 140.

[0066] When N energy storage units are charging the power battery 210, the method 40 may optionally include: During the charging stage, obtaining a current voltage of each energy storage battery; determining a second voltage output by a first DC / DC converter in each energy storage unit based on a current voltage of each energy storage battery, wherein the second voltage output by the first DC / DC converter in each energy storage unit is proportional to the current voltage of the energy storage battery in each energy storage unit; The method may further include sending a second control signal to a first DC / DC converter in each energy storage unit, the second control signal being used to control the first DC / DC converter to output a second voltage such that the energy storage battery in each energy storage unit charges the power battery 210 according to the second voltage via the first DC / DC converter in each energy storage unit.

[0067] Similarly, in the stage of charging the power battery 210, the output voltage of each first DC / DC converter can be controlled to adjust the amount of power that each energy storage unit charges to the power battery 210. For example, by adjusting the output voltage of the first DC / DC converter of each energy storage unit to be proportional to the current voltage of the energy storage battery, an energy storage battery with a higher SOC can transfer a larger amount of power to the power battery 210, and an energy storage battery with a lower SOC can transfer a smaller amount of power to the power battery 210, so that the amount of power provided by each energy storage unit can be matched to its current amount of power, and the capacity of each energy storage battery can be fully utilized, thereby improving the charging efficiency of the power battery.

[0068] Specifically, when the N energy storage units charge the power battery 210, the control module 160 can receive the charging voltage sent by the BMS 220, and this charging voltage is the voltage required to charge the power battery 210. At the same time, the control module 160 can obtain the current voltage of each energy storage unit, and adjust the second voltage output by the first DC / DC converter in each energy storage unit according to the charging voltage of the power battery 210 and the current voltage of the energy storage battery in each energy storage unit, so that this second voltage is proportional to the current voltage of the energy storage battery in each energy storage unit. The sum of the voltages of the N energy storage units in the charging process should be equal to this charging voltage of the power battery 210.

[0069] In this embodiment, the N energy storage units can charge the power battery 210 together with the AC power source 150, further improving the charging efficiency.

[0070] Alternatively, when the AC power source 150 can be used to receive power, i.e., allows grid-connected discharge, the power battery 210 may simultaneously discharge to the N energy storage units and the AC power source 150, and when the power battery 210 discharges to the AC power source 150, the control module 160 may send a fourth control signal to the AC / DC converter 140, which is used to control the discharge voltage output by the AC / DC converter 140 to be equal to the discharge voltage required for the power battery 210, so that the power battery 210 discharges to the AC power source 150 according to this discharge voltage through the AC / DC converter 140.

[0071] If the AC power source 150 is not available to receive power, i.e. does not allow grid-tied discharge, then the power battery 210 only needs to discharge to the N energy storage units.

[0072] As can be seen from this, when an AC / DC converter 140 is further connected between the power battery 210 and the AC power source 150, the AC / DC converter 140 can convert the AC power output by the AC power source 150 into stable DC power so that the AC power source 150 can charge the power battery 210. In addition, during the discharging phase of the power battery 210, the DC power output by the power battery 210 is converted into AC power, so that the power amount of the power battery 210 is released to the AC power source 150, and the power battery 210 can be simultaneously discharged to the N energy storage units and the AC power source 150, thereby shortening the time length of the discharging phase of the power battery 210 and further improving the charging efficiency.

[0073] Optionally, as shown in FIG. 6, the charging device 100 may further include an isolation unit 130.

[0074] Specifically, the isolation unit 130 is connected between the N energy storage units and the power battery 210, and the isolation unit 130 includes M second DC / DC converters and a switch module 133 connected between the M second DC / DC converters, where M is a positive integer greater than or equal to 2.

[0075] The control module 160 can control the switch module 133 to connect M second DC / DC converters in series, and at this time, the voltage output by the isolation unit 130 to the power battery 210 is equal to M times the voltage output by the N energy storage units.

[0076] The control module 160 can also control the switch module 133 to connect M second DC / DC converters in parallel, where the current output by the isolation unit 130 to the power battery 210 is equal to M times the current output by the N energy storage units.

[0077] Taking M=2 as an example, as shown in Fig. 6, the isolation unit 130 includes two second DC / DC converters, namely, the second DC / DC converter 131 and the second DC / DC converter 132. When the N energy storage units charge the power battery 210, the sides of the second DC / DC converter 131 and the second DC / DC converter 132 connected to the N energy storage units are input ends, and the sides connected to the power battery 210 are output ends. Here, the input end of the second DC / DC converter 131 and the input end of the second DC / DC converter 132 are connected in parallel, and a switch module 133 is connected between the output end of the second DC / DC converter 131 and the output end of the second DC / DC converter 132.

[0078] For example, as shown in Fig. 6, the switch module 133 may include a switch K1, a switch K2, and a switch K3. When the energy storage unit charges the power battery 210, the control module 160 can control the switch K1 in the switch module 133 to be closed, so that the output terminal of the second DC / DC converter 131 and the output terminal of the second DC / DC converter 132 are connected in series. In this way, the voltage output by the isolation unit 130 to the power battery 210 is equal to twice the total voltage output by the N energy storage units.

[0079] When the energy storage units charge the power battery 210, the control module 160 can control the switch K2 and the switch K3 in the switch module 133 so that the output terminal of the second DC / DC converter 131 and the output terminal of the second DC / DC converter 132 are connected in parallel. In this way, the current output by the isolation unit 130 to the power battery 210 is equal to twice the current output by the N energy storage units.

[0080] As can be seen, the isolation unit 130 includes M second DC / DC converters and a switch module 133 connected between the M second DC / DC converters, so that the isolation unit 130 is installed to be connected between the N energy storage units and the power battery 210. The switch module 133 can be controlled to change the series-parallel connection relationship at the output ends of the M second DC / DC converters, thereby realizing the adjustment of the voltage output by the isolation unit 130 to the power battery 210. Here, when the switch module 133 of the isolation unit 130 is controlled so that the M second DC / DC converters are connected in series, a high voltage charging to the power battery 210 can be realized, and when the switch module 133 of the isolation unit 130 is controlled so that the M second DC / DC converters are connected in parallel, the currents output by the second DC / DC converters are superimposed, so that a high current charging to the power battery 210 can be realized.

[0081] Fig. 7 is a schematic flow chart of a possible implementation of the charging method shown in Fig. 4, which realizes rapid charging of the power battery 210 by periodically charging and discharging the power battery 210. As shown in Fig. 7, the method 70 may be implemented by the above-mentioned control module 160, for example, an EMS. Taking the charging device 100 shown in Fig. 5 as an example, the method 70 includes the following steps:

[0082] Step 701: After detecting that the connection between the charging device 100 and the battery system 200 is successful, turn on the charging of the power battery 210.

[0083] Step 702: Obtain the charging voltage of the power battery 210, and detect the current voltage of the energy storage battery in each energy storage unit.

[0084] Step 703: Determine the output voltage of the first DC / DC converter and the output voltage of the AC / DC converter 140 in each energy storage unit.

[0085] Here, the output voltage of the AC / DC converter 140 is equal to the charging voltage required for the power battery 210. The second voltage output by the first DC / DC converter in each energy storage unit is proportional to the current voltage of the energy storage battery in each energy storage unit, thus the energy storage battery with a larger SOC will transfer more power to the power battery 210, and the energy storage battery with a smaller SOC will transfer less power to the power battery 210, thus avoiding the energy mismatch between different energy storage batteries and improving the charging efficiency.

[0086] Step 704: Send a second control signal to a first DC / DC converter in each energy storage unit.

[0087] Here, this second control signal is used to control the first DC / DC converter to output a second voltage, so that the energy storage battery in each energy storage unit charges the power battery 210 according to this second voltage via the first DC / DC converter in each energy storage unit.

[0088] Concurrently with performing step 704 , a third control signal is sent to AC / DC converter 140 in step 705 .

[0089] Here, this third control signal is used to control the voltage output by the AC / DC converter 140 to be equal to the charging voltage of the power battery 210, so that the AC power source 150 charges the power battery 210 according to this charging voltage.

[0090] Step 706: Determine whether charging is complete.

[0091] For example, when the voltage of the power battery 210 reaches the full charge voltage, the control module 160 receives a charge stop message sent by the BMS 220. When the control module 160 receives this charge stop message, it determines that charging is complete, terminates charging, and executes step 716; when the control module 160 does not receive the charge stop message, it determines that charging is not complete, and executes step 707.

[0092] Step 707: Record the charging time, and determine whether the preset time of charging has been reached.

[0093] The preset time of the charging is the time of the charging stage for charging the power battery 210 in each charging cycle, and accordingly, the preset time of the discharging is the time of the discharging stage for discharging the power battery 210 in each charging cycle. By alternating the charging stage and the discharging stage, rapid charging of the power battery 210 is realized.

[0094] If the preset time of charging has not been reached, it continues to charge the power battery 210 according to the above steps, and enters the discharge phase of this charging cycle when the preset time of charging is reached.

[0095] Step 708: Obtain the discharge voltage of the power battery 210, and detect the current voltage of the energy storage battery in each energy storage unit.

[0096] Step 709: Determine the output voltage of the first DC / DC converter and the output voltage of the AC / DC converter 140 in each energy storage unit.

[0097] Here, the output voltage of the AC / DC converter 140 is equal to the discharge voltage of the power battery 210. The first voltage output by the first DC / DC converter in each energy storage unit is inversely proportional to the current voltage of the energy storage battery in each energy storage unit, thus the energy storage battery with a larger SOC receives less power from the power battery 210, and the energy storage battery with a smaller SOC receives more power from the power battery 210, thus avoiding the energy mismatch between different energy storage batteries and improving the charging efficiency.

[0098] Step 710: Send a first control signal to a first DC / DC converter in each energy storage unit.

[0099] Here, the first control signal is used to control the first DC / DC converter to output a first voltage, so that the energy storage battery in each energy storage unit receives the amount of power released by the power battery 210 according to the first voltage via the first DC / DC converter in each energy storage unit.

[0100] While performing step 710, it is determined in step 711 whether the power battery 210 is allowed to discharge to the AC power source 150.

[0101] If the power battery 210 does not allow discharging to the AC power source 150, execute step 712; otherwise, execute step 713.

[0102] Step 712: Send a stop signal to the AC / DC converter 140.

[0103] This stop signal is used to control turning off of AC / DC converter 140.

[0104] Step 713 : Send a third control signal to the AC / DC converter 140 .

[0105] Here, this third control signal is used to control the voltage output by the AC / DC converter 140 to be equal to the discharge voltage of the power battery 210, so that the AC power source 150 receives the amount of power released by the power battery 210 according to this discharge voltage.

[0106] Step 714: Determine whether charging is complete.

[0107] For example, when the voltage of the power battery 210 reaches the full charge voltage, the control module 160 receives a charge stop message sent by the BMS 220. When the charge stop message is received, it determines that charging is complete, terminates charging, and executes step 716; when the charge stop message is not received, it determines that charging is not complete, and executes step 715.

[0108] Step 715: Record the charging time and determine whether the preset time of discharging has been reached.

[0109] The preset time of discharge is the time of the discharge phase for the power battery 210 to discharge in each charging cycle.

[0110] If the preset time of discharge has not been reached, the power battery 210 continues to discharge into the N energy storage units based on the above steps, and enters the charging phase of the next charging cycle if the preset time of discharge is reached.

[0111] Step 716: Charging is terminated.

[0112] As can be seen from FIG. 7, the control module 160 controls the output voltage of each first DC / DC converter in the charging phase and the discharging phase to control the amount of power discharged or received by the energy storage unit in each energy storage unit, thereby avoiding the energy mismatch occurring between each energy storage unit, realizing full utilization of each energy storage unit, and improving charging efficiency.

[0113] An embodiment of the present application further provides an EMS including a processor for executing the charging method in each embodiment of the present application.

[0114] An embodiment of the present application further provides a charging system, characterized in that it includes a power battery and the charging device 100 described in any one of the above embodiments. The charging device 100 is used to charge the power battery 210, where each charging cycle includes a step of charging the power battery 210 and a step of discharging the power battery 210.

[0115] It should be understood that the specific examples in this specification are merely intended to assist those skilled in the art in better understanding the embodiments of the present application, and are not intended to limit the scope of the embodiments of the present application.

[0116] It should be further understood that in various embodiments of the present application, the execution order of each process does not constitute any limitation on the implementation process of the embodiments of the present application, but should be determined by its function and inherent logic.

[0117] It should be further understood that the various embodiments described herein may be implemented alone or in combination, and the examples of this application are not limited thereto.

[0118] Although the present application has been described with reference to the preferred embodiments, various modifications may be made thereto and equivalents may be substituted for the components therein without departing from the scope of the present application. In particular, unless there is a structural conflict, each technical feature mentioned in each embodiment may be combined in any manner. The present application is not limited to the specific embodiments disclosed in the specification, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for charging a power battery, which is used in a charging device, the charging device includes N energy storage units connected in series, where each energy storage unit includes an energy storage battery and a first DC / DC converter connected with the energy storage battery, each charging cycle of the charging device includes a step of charging the power battery and a step of discharging the power battery to the N energy storage units, N is a positive integer greater than 1; The charging method includes: In the discharging step, obtaining a current voltage of an energy storage battery in each of the energy storage units; determining a first voltage output by a first DC / DC converter in each of the energy storage units based on a current voltage of an energy storage battery in each of the energy storage units, wherein the first voltage output by the first DC / DC converter in each of the energy storage units is inversely proportional to the current voltage of the energy storage battery in each of the energy storage units; sending a first control signal to a first DC / DC converter in each of the energy storage units, the first control signal being used to control the first DC / DC converter to output the first voltage, such that the energy storage battery in each of the energy storage units receives an amount of power released by the power battery according to the first voltage through the first DC / DC converter in each of the energy storage units; The charging device further includes an isolation unit, the isolation unit is connected between the N energy storage units and the power battery, the isolation unit includes M second DC / DC converters and a switch module connected between the M second DC / DC converters, where M is a positive integer greater than or equal to 2; The charging method includes: Controlling the switch module to connect the M second DC / DC converters in series, so that the voltage output by the isolation unit to the power battery is equal to M times the voltage output by the N energy storage units; or The method for charging a power battery further comprises controlling the switch module to connect the M second DC / DC converters in parallel, so that the current output by the isolation unit to the power battery is equal to M times the current output by the N energy storage units.

2. The charging method includes: In the charging step, obtaining a current voltage of an energy storage battery in each of the energy storage units; determining a second voltage output by a first DC / DC converter in each of the energy storage units based on a current voltage of an energy storage battery in each of the energy storage units, wherein the second voltage output by the first DC / DC converter in each of the energy storage units is proportional to the current voltage of the energy storage battery in each of the energy storage units; 2. The charging method according to claim 1, further comprising: sending a second control signal to a first DC / DC converter in each of the energy storage units, the second control signal being used to control the first DC / DC converter to output the second voltage, so that an energy storage battery in each of the energy storage units charges the power battery according to the second voltage via the first DC / DC converter in each of the energy storage units.

3. The charging device further includes an AC / DC converter connected between the power battery and an AC power source; The charging method includes:

3. The charging method according to claim 1 or 2, further comprising: sending a third control signal to the AC / DC converter, the third control signal being used to control a voltage output by the AC / DC converter to be equal to a charging voltage of the power battery, thereby causing the AC power source to charge the power battery according to the charging voltage via the AC / DC converter.

4. The charging method includes:

4. The charging method according to claim 3, further comprising: transmitting a fourth control signal to the AC / DC converter, the fourth control signal being used to control a voltage output by the AC / DC converter to be equal to a discharge voltage of the power battery, thereby causing the power battery to discharge to the AC power source via the AC / DC converter in accordance with the discharge voltage.

5. A charging device for a power battery, comprising: N energy storage units connected in series; and a control module, wherein each energy storage unit comprises an energy storage battery and a first DC / DC converter connected to the energy storage battery; each charging cycle of the charging device comprises: charging the power battery; and discharging the power battery to the N energy storage units, where N is a positive integer greater than 1; The control module includes: In the discharging step, obtaining a current voltage of an energy storage battery in each of the energy storage units; determining a first voltage output by a first DC / DC converter in each of the energy storage units based on a current voltage of an energy storage battery in each of the energy storage units, wherein the first voltage output by the first DC / DC converter in each of the energy storage units is inversely proportional to the current voltage of the energy storage battery in each of the energy storage units; sending a first control signal to a first DC / DC converter in each of the energy storage units, the first control signal being used to control the first DC / DC converter to output the first voltage, such that the energy storage battery in each of the energy storage units receives an amount of power released by the power battery according to the first voltage through the first DC / DC converter in each of the energy storage units; The charging device further includes an isolation unit, the isolation unit is connected between the N energy storage units and the power battery, the isolation unit includes M second DC / DC converters and a switch module connected between the M second DC / DC converters, where M is a positive integer greater than or equal to 2; The control module further comprises: Controlling the switch module to connect the M second DC / DC converters in series, so that the voltage output by the isolation unit to the power battery is equal to M times the total voltage output by the N energy storage units; or A charging device for a power battery, characterized in that it is used for controlling the switch module to connect the M second DC / DC converters in parallel, thereby making the current output by the isolation unit to the power battery equal to M times the current output by the N energy storage units.

6. The control module further comprises: In the charging step, obtaining a current voltage of an energy storage battery in each of the energy storage units; determining a second voltage output by a first DC / DC converter in each of the energy storage units based on a current voltage of an energy storage battery in each of the energy storage units, wherein the second voltage output by the first DC / DC converter in each of the energy storage units is proportional to the current voltage of the energy storage battery in each of the energy storage units; 6. The charging device according to claim 5, further comprising: a first DC / DC converter in each of the energy storage units, the second control signal being used to control the first DC / DC converter to output the second voltage, so that the energy storage battery in each of the energy storage units charges the power battery according to the second voltage via the first DC / DC converter in each of the energy storage units.

7. The charging device further includes an AC / DC converter connected between the power battery and an AC power source; The control module further comprises:

7. The charging device according to claim 5 or 6, characterized in that the charging device is used to send a third control signal to the AC / DC converter, and the third control signal is used to control the voltage output by the AC / DC converter to be equal to the charging voltage of the power battery, thereby causing the AC power source to charge the power battery according to the charging voltage via the AC / DC converter.

8. The control module further comprises:

8. The charging device according to claim 7, which is used to send a fourth control signal to the AC / DC converter, and the fourth control signal is used to control the voltage output by the AC / DC converter to be equal to the discharge voltage of the power battery, thereby causing the power battery to discharge to the AC power source via the AC / DC converter in accordance with the discharge voltage.

9. An EMS including a processor for executing the charging method described in any one of claims 1 to 4.

10. 1. A charging system comprising: A power battery; 9. A charging system comprising: a charging device according to any one of claims 5 to 8, wherein the charging device is used to charge the power battery, and each charging cycle includes a step of charging the power battery and a step of discharging the power battery.

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