A charging method, charging device and charging system for a power battery

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 applied to a charging device. The charging device includes N energy storage units connected in series, wherein each energy storage unit includes 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 stage of charging the power battery and a stage of discharging the N energy storage units by the power battery. The charging method includes: in the discharge stage, obtaining the current voltage of the energy storage battery in each energy storage unit; determining the 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, wherein the first voltage is inversely proportional to the current voltage of the energy storage battery; sending the first voltage to the first DC / DC converter so that the energy storage battery receives the amount of electricity released by the power battery through the first DC / DC converter according to the first voltage.

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 Art

[0002] With the increasing consumption of non-renewable energy and the urgent need for environmental protection, new energy electric vehicles (EVs) using rechargeable batteries as their power source are rapidly developing. Currently, fast charging of power batteries can be achieved by alternating between charging and discharging. During the discharge process, an energy storage unit can be provided to receive the power released by the power battery. However, due to factors such as the capacity of the energy storage unit, further improvements in power battery charging efficiency are limited. 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, which can improve charging efficiency.

[0004] In a first aspect, the present application provides a method for charging a power battery, which is applied to a charging device. The charging device includes N energy storage units connected in series, each of which includes 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 phase in which the power battery is charged, and a phase in which the power battery discharges the N energy storage units, where N is a positive integer greater than 1. The charging method includes: during the discharge phase, obtaining the 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, wherein 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 transmitting a first control signal to the first DC / DC converter in each energy storage unit, the first control signal being 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 power discharged by the power battery through the first DC / DC converter in each energy storage unit at the first voltage.

[0005] The embodiment of the present application realizes rapid charging of the power battery based on an alternating charge and discharge method. Since the charging device includes multiple energy storage units connected in series, and each energy storage unit includes an energy storage battery and a first DC / DC converter connected thereto, the amount of electricity 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. In this way, the amount of electricity borne by each energy storage unit can be matched with its current amount of electricity, avoiding the problem of energy mismatch between the energy storage units, thereby achieving full utilization of the capacity of each energy storage unit, enabling each energy storage unit to more effectively receive the electricity released by the power battery, and improving the charging efficiency of the power battery.

[0006] In a possible embodiment, the charging method further includes: during the charging stage, obtaining the current voltage of the energy storage battery in each energy storage unit; determining the 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 can be adjusted to be proportional to the current voltage of the energy storage battery, so that the power provided by each energy storage unit is more closely matched with its current power, thereby further achieving full utilization of the capacity of each energy storage battery and improving the charging efficiency of the power battery.

[0008] 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 including 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 a possible embodiment, the charging method further 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 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.

[0010] The above embodiment also provides an isolation unit connected between 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. By controlling the switch module, the connection between the M second DC / DC converters can be changed, thereby adjusting the output voltage of the isolation unit. When the switch module of the isolation unit is controlled so that the M second DC / DC converters are connected in series, the charging device can charge the power battery at a high voltage; when the switch module of the isolation unit is controlled so that the M second DC / DC converters are connected in parallel, the charging device can charge the power battery at a high current.

[0011] In one possible embodiment, the charging device further includes an AC / DC converter connected between the power battery and the AC power source. The charging method further includes: sending a third control signal to the AC / DC converter, where the third control signal is used to control the AC / DC converter to output a voltage 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.

[0012] In a possible embodiment, the above-mentioned charging method further includes: sending a fourth control signal to the AC / DC converter, where 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, so that the power battery discharges to the AC power supply through 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 supply. The AC / DC converter can not only convert the AC power output by the AC power supply 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 discharge phase of the power battery, thereby releasing the power of the power battery into the AC power supply, enabling the power battery to discharge to the energy storage unit and the AC power supply at the same time, reducing the duration of the discharge phase of the power battery and further improving the charging efficiency.

[0014] In a second aspect, the present application provides a charging device for a power battery, comprising N energy storage units connected in series and a control module, wherein each energy storage unit includes 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 phase in which the power battery is charged, and a phase in which the power battery discharges the N energy storage units, where N is a positive integer greater than 1. The control module is configured to: during the discharge phase, obtain the current voltage of the energy storage battery in each energy storage unit; determine 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, wherein 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 send a first control signal to the first DC / DC converter in each energy storage unit, the first control signal being configured to control the first DC / DC converter to output the first voltage so that the energy storage battery in each energy storage unit receives the power discharged by the power battery through the first DC / DC converter in each energy storage unit at the first voltage.

[0015] The charging device of the embodiment of the present application realizes rapid charging of the power battery based on an alternating charge and discharge method. Since the charging device includes multiple energy storage units connected in series, and each energy storage unit includes an energy storage battery and a first DC / DC converter connected thereto, the amount of electricity 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. In this way, the amount of electricity borne by each energy storage unit can be matched with its current amount of electricity, avoiding the problem of energy mismatch between the energy storage units, thereby achieving full utilization of the capacity of each energy storage unit, enabling each energy storage unit to more effectively receive the electricity released by the power battery, and improving the charging efficiency of the power battery.

[0016] In a possible embodiment, the control module is further configured to: obtain the current voltage of the energy storage battery in each energy storage unit during the charging phase; determine the 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 send a second control signal to the first DC / DC converter in each energy storage unit, wherein the second control signal is configured 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 can be adjusted to be proportional to the current voltage of the energy storage battery, so that the power provided by each energy storage unit is more closely matched with its current power, thereby further achieving full utilization of the capacity of each energy storage battery and 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 greater than or equal to 2. The control module is further configured to: control 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 control 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.

[0019] The above embodiment provides an isolation unit connected between N energy storage units and a power battery. The isolation unit includes M second DC / DC converters and a switch module connected between the M second DC / DC converters. By controlling the switch module, the connection between the M second DC / DC converters can be changed, thereby adjusting the output voltage of the isolation unit. When the switch module of the isolation unit is controlled so that the M second DC / DC converters are connected in series, high-voltage charging of the power battery can be achieved; when the switch module of the isolation unit is controlled so that the M second DC / DC converters are connected in parallel, high-current charging of the power battery can be achieved.

[0020] In one possible embodiment, the charging device further includes an AC / DC converter connected between the power battery and the AC power source. The control module is further configured to send a third control signal to the AC / DC converter, which is configured to control the AC / DC converter to output a voltage 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 a possible embodiment, the above-mentioned control module is also 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, so that the power battery discharges to the AC power supply through 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 supply. The AC / DC converter can not only convert the AC power output by the AC power supply 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 discharge phase of the power battery, thereby releasing the power of the power battery into the AC power supply, enabling the power battery to discharge to the energy storage unit and the AC power supply at the same time, reducing the duration of the discharge phase of the power battery and further improving the charging efficiency.

[0023] In a third aspect, the present application provides an EMS, comprising a processor, configured to execute the method in the first aspect and any possible embodiment of the first aspect.

[0024] In a fourth aspect, an embodiment of the present application provides a charging system, comprising a power battery and a charging device according to the second aspect or any possible embodiment of the second aspect, wherein the charging device is used to charge the power battery, wherein each charging cycle includes a stage of charging the power battery and a stage of discharging the power battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0026] Figure 1 It is a structural diagram of a charging system according to an embodiment of the present application.

[0027] Figure 2 2 is a schematic diagram of a charging cycle according to an embodiment of the present application.

[0028] Figure 3 It is a structural diagram of a charging device according to an embodiment of the present application.

[0029] Figure 4 It is a flowchart of a charging method according to an embodiment of the present application.

[0030] Figure 5 It is a structural schematic diagram of a charging device according to another embodiment of the present application.

[0031] Figure 6 It is a structural diagram of a charging device according to another embodiment of the present application.

[0032] Figure 7 is based on Figure 4 A flowchart of a specific implementation of the charging method is shown. DETAILED DESCRIPTION

[0033] The following detailed description of the embodiments of the present application is provided in conjunction with the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present application, but are not intended to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

[0034] The following detailed description of the embodiments of the present application is provided in conjunction with the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present application, but are not intended to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

[0035] In the description of this application, it should be noted that, unless otherwise specified, "plurality" means more than two; terms such as "upper," "lower," "left," "right," "inner," and "outer" indicating directions or positional relationships are merely for the purpose of facilitating the description of this application and simplifying the description, and do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting this application. Furthermore, terms such as "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0036] The directional words appearing in the following description are all directions shown in the figures, and do not limit the specific structure of this application. In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0037] In the field of new energy, power batteries can serve as the primary power source for electrical devices, such as vehicles, ships, or spacecraft, while energy storage batteries can serve as a charging source for these devices. The importance of both is self-evident. By way of example and not limitation, in some application scenarios, power batteries can be the batteries in electrical devices, and energy storage batteries can be the batteries in charging devices.

[0038] Figure 1 A structural schematic diagram of a charging system applicable to an embodiment of the present application is shown.

[0039] like Figure 1 As shown, the charging system 100 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.

[0040] Optionally, at least one battery pack may be provided in the battery system 200, and the at least one battery pack as a whole may be collectively referred to as a power battery 210. In terms of battery type, the power battery 210 may be any type of battery, including but not limited to: lithium-ion batteries, lithium metal batteries, lithium-sulfur batteries, lead-acid batteries, nickel-cathode accumulators, nickel-metal hydride batteries, or lithium-air batteries, etc. In terms of battery scale, the power battery 210 in the embodiment of the present application may be a battery cell / battery monomer (cell), or a battery module or battery pack, wherein the battery module or battery pack may be formed by multiple batteries connected in series and parallel. In the embodiment of the present application, the specific type and scale of the power battery 210 are not specifically limited.

[0041] Furthermore, to intelligently manage and maintain the power battery 210, prevent overcharging and overdischarging, and extend the battery's service life, the battery system 200 is generally further provided with a battery management system (BMS) 220 for monitoring the status of the power battery 210. Optionally, the BMS 220 can be integrated with the power battery 210 and provided in the same device or apparatus, or the BMS 220 can be provided as an independent device / apparatus outside the power battery 210.

[0042] Specifically, the charging device 100 is a device for replenishing electric energy for the power battery 210 in the battery system 200 .

[0043] Optionally, the charging device 100 in the embodiment of the present application can be a common charging pile, a super charging pile, a charging pile supporting vehicle to grid (V2G) mode, or a charging device or equipment capable of charging a battery. The embodiment of the present application does not limit the specific type and specific application scenario of the charging device 100.

[0044] Alternatively, as Figure 1 As shown, the charging device 100 can be connected to the power battery 210 via a wire 300 and connected to the BMS 220 via a communication line 400. The communication line 400 is used to implement information exchange between the charging device 100 and the BMS 220.

[0045] As an example, the communication line 400 includes but is not limited to a controller area network (CAN) communication bus or a daisy chain communication bus.

[0046] Optionally, the charging device 100 can communicate with the BMS 220 via a wireless network in addition to the communication line 400. The embodiment of the present application does not specifically limit the type of communication between the charging device 100 and the BMS 220.

[0047] When the power battery 210 is continuously charged using a conventional charging method, the charging current is limited due to the accumulation of lithium ions at the negative electrode of the battery during the continuous charging process, making it impossible to achieve rapid charging of the battery using a continuous high current. To achieve rapid charging of the power battery 210, the embodiment of the present application adopts a method of alternating charging and discharging of the power battery 210 to achieve rapid charging of the power battery 210.

[0048] For example, Figure 2 As shown, a charging cycle T includes a charging phase for the power battery 210 and a discharging phase for the power battery 210. During the charging phase, the charging current is +I1; during the discharging phase, the charging current is -I2. After high-current charging of the power battery 210, the power battery 210 discharges to release lithium ions accumulated at the negative electrode of the power battery 210 during the charging process. This prevents lithium deposition and heat generation in the power battery 210. Therefore, the power battery 210 can be charged again with a high current, thereby achieving rapid charging of the power battery 210.

[0049] The charging device 100 of the embodiment of the present application is provided with an energy storage unit, which is used to receive the electricity released by the power battery 210 during the discharge 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 electricity that the power battery 210 can release. In order to increase the capacity of the energy storage battery, the energy storage battery can include a large number of battery cells. When a large number of battery cells are connected in series, if the consistency of the battery cells is poor, the failure of individual battery cells will cause 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 cells can be respectively arranged in multiple energy storage batteries, that is, multiple energy storage batteries are used to simultaneously receive the electricity released by the power battery 210. In this way, when a battery cell in one of the energy storage batteries fails, through a certain method, such as bypassing the energy storage battery, the charging of the power battery 210 can be unaffected, thereby improving the reliability of charging.

[0050] These multiple energy storage batteries can be connected in series. When the power battery 210 discharges simultaneously into the multiple energy storage batteries in series, the voltages across the two ends of the energy storage batteries may differ due to differences in the charge levels of the multiple energy storage batteries. Since the currents in the multiple energy storage batteries connected in series are equal, the amount of charge released by the power battery 210 to the multiple energy storage batteries will be different. For example, for an energy storage battery with a lower state of charge (SOC), the voltage across its two ends is lower. Therefore, over a certain period of time, the power battery 210 will release less charge to the energy storage battery. For an energy storage battery with a higher SOC, the voltage across its two ends is higher. Therefore, over the same period of time, the power battery 210 will release more charge to the energy storage battery. This can lead to energy mismatch between the energy storage batteries. An energy storage battery with a lower SOC receives less charge, while an energy storage battery with a higher SOC receives more charge, making it easier for the energy storage battery to reach full charge. Because the multiple energy storage cells exhibit a short-board effect, when one of the energy storage cells reaches full charge, charging of the power battery 210 is terminated to ensure safety. This energy mismatch between the energy storage cells prevents the full utilization of the capacity of each energy storage unit, preventing further improvement in the charging efficiency of the power battery 210.

[0051] To this end, an embodiment of the present application proposes a charging scheme for a power battery. By setting a first DC / DC converter to control the charging voltage and discharge voltage of each energy storage battery, the amount of electricity received and released by each energy storage battery matches its current capacity, avoiding energy mismatch between the energy storage batteries and improving the charging efficiency of the power battery.

[0052] Figure 3 The schematic diagram of the structure of the charging device 100 of the embodiment of the present application is shown. The charging device 100 can be a charging pile or a charger, or other types of fixed or mobile charging devices, which are not limited here.

[0053] The charging device 100 may include N energy storage units connected in series, such as energy storage unit 110 and energy storage unit 120, where N is a positive integer greater than 1. Each charging cycle of the charging device 100 includes a phase in which the power battery 210 is charged, and a phase in which the power battery 210 discharges the N energy storage units.

[0054] like Figure 3 As shown, each energy storage unit includes an energy storage battery and a first DC / DC converter connected to the energy storage battery. For example, energy storage unit 110 includes energy storage battery 111 and a first DC / DC converter 112 connected to energy storage battery 111, and energy storage unit 120 includes energy storage battery 121 and a first DC / DC converter 122 connected to energy storage battery 121.

[0055] Specifically, the energy storage battery in each energy storage unit can be connected in parallel to the first DC side of the first DC / DC converter in the energy storage unit, that is, the side where port A and port B are located, and the two electrodes of the energy storage battery can 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, that is, the side where port C and port D are located are connected in series. For example, Figure 3 As shown, 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, that is, on one side of port A and port B of the first DC / DC converter 112. 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, that is, on one side of port A and port B of the first DC / DC converter 122. In addition, the second DC side of the first DC / DC converter 112 is connected in series with the second DC side of the first DC / DC converter 122.

[0056] from Figure 3 As can be seen, the first DC side of the first DC / DC converter is the side of the first DC / DC converter used to connect to the energy storage battery, and the second DC side of the first DC / DC converter is the side of the first DC / DC converter used to connect to the power battery 210. It should be noted that when the energy storage battery is charging 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 is discharging to 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.

[0057] Optionally, the first DC / DC converter may be a voltage-type converter that effectively outputs a fixed voltage after converting an input voltage, for example, may be configured as a buck-boost DC / DC converter.

[0058] Optionally, the N energy storage units may be N single energy storage boxes, and the energy storage batteries in the N energy storage units may be battery modules or battery packs. Both the battery modules and the battery packs may be formed by multiple battery cells connected in series or in parallel.

[0059] Furthermore, the charging device 100 may also include a control module 160. The control module 160 may be connected to the N energy storage units and configured to control the first DC / DC converters in the N energy storage units, so that the power battery 210 discharges energy to the energy storage units through the first DC / DC converters, or so that the energy storage units charge the power battery 210 through the first DC / DC converters. The control module 160 may also be connected to the battery management system 220 of the power battery 210 via a communication line 400 to enable information exchange between the charging device 100 and the BMS 220.

[0060] The control module 160 may be, for example, an energy management system (EMS) controller in a charging station or a charger. Furthermore, the control module 160 may also include an auxiliary power system.

[0061] Optionally, Figure 4 A charging method 40 according to an embodiment of the present application is shown, which is used to charge the power battery 210. The method 40 may be executed by the control module 160 described above, and may specifically include some or all of the following steps.

[0062] Step 410: During the discharging phase, the current voltage of the energy storage battery in each energy storage unit is obtained.

[0063] Step 420 : Determine a first voltage output by the first DC / DC converter in each energy storage unit according to the discharge voltage of the power battery 210 .

[0064] 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.

[0065] Step 430: Send a first control signal to the first DC / DC converter in each energy storage unit. 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 power released by the power battery 210 at the first voltage through the first DC / DC converter in each energy storage unit.

[0066] In the embodiment of the present application, rapid charging of the power battery 210 is achieved based on an alternating charge and discharge method. Since 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, the amount of power discharged from the power battery 210 to each energy storage unit can be adjusted by controlling the output voltage of each first DC / DC converter. By adjusting the output voltage of the first DC / DC converter of each energy storage unit to be inversely proportional to the current voltage of the energy storage battery, the amount of power received by each energy storage unit can be matched to its current power, avoiding energy mismatch problems between the various energy storage units. This allows full utilization of the capacity of each energy storage unit, allowing each energy storage unit to more effectively receive the power released by the power battery, thereby improving the charging efficiency of the power battery.

[0067] Specifically, when the power battery 210 discharges to N energy storage units, the control module 160 can receive the discharge voltage sent by the BMS 220. This discharge voltage is the voltage required for the power battery 210 to discharge. The control module 160 can simultaneously obtain the current voltage of the energy storage battery in each energy storage unit, and then 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 the first voltage is inversely 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 during the discharge process is equal to the discharge voltage of the power battery 210.

[0068] For example, if the current charge of energy storage cell 111 in energy storage unit 110 is low, i.e., its SOC is low, then the voltage across energy storage cell 111 is also low. Meanwhile, if the current charge of energy storage cell 121 in energy storage unit 120 is high, i.e., its SOC is high, then the voltage across energy storage cell 121 is also high. Because energy storage cells 110 and 120 are connected in series, the current discharged from power battery 210 to both energy storage cells 110 and 120 is equal. The greater the voltage and current of the energy storage cells when power battery 210 discharges to the energy storage cells, the greater the charge received by the energy storage cells from power battery 210. This results in power battery 210 releasing less charge to energy storage cell 111 (with a lower SOC) and more charge to energy storage cell 121 (with a higher SOC), resulting in an energy mismatch between the two energy storage cells. Since energy storage cell 121 (with a higher SOC) will be fully charged quickly, charging of power battery 210 is terminated for safety reasons.

[0069] At this time, when the current voltage of the energy storage battery 111 is relatively low, the control module 160 controls the first DC / DC converter 112 connected to the energy storage battery 111 to output a relatively high first voltage to the energy storage battery 111. Correspondingly, when the current voltage of the energy storage battery 121 is relatively high, the control module 160 controls the first DC / DC converter 122 connected to the energy storage battery 121 to output a relatively low first voltage to the energy storage battery 122. In this way, the amount of electricity received by the energy storage unit can be matched to its current amount of electricity. The energy storage battery 111 with a low current voltage or low amount of electricity can receive more electricity from the power battery 210, while the energy storage battery 112 with a high current voltage or high amount of electricity can receive less electricity from the power battery 210. As a result, the energy between the various energy storage units is relatively balanced after the power battery 210 is discharged, fully utilizing the capacity of each energy storage unit and improving charging efficiency.

[0070] The above describes how the control module 160 controls the first DC / DC converter during the discharge phase of the power battery 210 to the N energy storage units. Accordingly, the control module 160 can also control the first DC / DC converter during the charging phase of the N energy storage units to the power battery 210 to make the energy between the N energy storage units more balanced.

[0071] It should be understood that in the embodiment of the present application, the power battery 210 may be charged only by the AC power source 150, that is, the power grid, or the power battery 210 may be charged by N energy storage units and the AC power source 150. Figure 5 As shown, the charging device 100 also includes an AC / DC converter 140, which is connected between the power battery 210 and the AC power source 150. When charging the power battery 210, the AC power output by the AC power source 150 is converted into stable DC power through the AC / DC converter 140, thereby charging the power battery 210.

[0072] Specifically, when the AC power supply 150 charges the power battery 210, the control module 160 can send a third control signal to the AC / DC converter 140. The 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 supply 150 charges the power battery 210 according to the charging voltage through the AC / DC converter 140.

[0073] When the N energy storage units charge the power battery 210, the method 40 may optionally further include:

[0074] During the charging phase, obtain the current voltage of each energy storage battery;

[0075] Determining a second voltage output by the first DC / DC converter in each energy storage unit based on the 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;

[0076] A second control signal is sent 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 a second voltage, so that the energy storage battery in each energy storage unit charges the power battery 210 according to the second voltage through the first DC / DC converter in each energy storage unit.

[0077] In this way, similarly, during the stage of charging the power battery 210, the amount of electricity charged by each energy storage unit to the power battery 210 can also 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 proportional to the current voltage of the energy storage battery, so that energy storage batteries with a large SOC transfer more electricity to the power battery 210, and energy storage batteries with a small SOC transfer less electricity to the power battery 210. This can make the electricity provided by each energy storage unit more compatible with its current electricity, achieve full utilization of the capacity of each energy storage battery, and improve the charging efficiency of the power battery.

[0078] Specifically, when N energy storage units are charging the power battery 210, the control module 160 can receive the charging voltage sent by the BMS 220. 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, based on the charging voltage of the power battery 210 and the current voltage of the energy storage battery in each energy storage unit, adjust the second voltage output by the first DC / DC converter in each energy storage unit so that the second voltage is proportional to the current voltage of the energy storage battery in each energy storage unit. During the charging process, the sum of the voltages of the N energy storage units should be equal to the charging voltage of the power battery 210.

[0079] In this embodiment, since the N energy storage units can charge the power battery 210 together with the AC power source 150 , the charging efficiency is further improved.

[0080] Optionally, if the AC power supply 150 can be used to receive electricity, that is, grid-connected discharge is allowed, then the power battery 210 can discharge to N energy storage units and the AC power supply 150 at the same time. When the power battery 210 discharges to the AC power supply 150, the control module 160 can send a fourth control signal to the AC / DC converter 140. The fourth control signal is used to control the discharge voltage output by the AC / DC converter 140 to be equal to the discharge voltage required by the power battery 210, so that the power battery 210 discharges to the AC power supply 150 through the AC / DC converter 140 according to the discharge voltage.

[0081] If the AC power source 150 is unable to receive power, that is, the grid-connected discharge is not allowed, then the power battery 210 only needs to discharge to the N energy storage units.

[0082] It can be seen that when the AC / DC converter 140 is also connected between the power battery 210 and the AC power supply 150, the AC / DC converter 140 can not only convert the AC power output by the AC power supply 150 into stable DC power so that the AC power supply 150 can charge the power battery 210, but also convert the DC power output by the power battery 210 into AC power during the discharge phase of the power battery 210, thereby releasing the power of the power battery 210 into the AC power supply 150, enabling the power battery 210 to discharge to N energy storage units and the AC power supply 150 at the same time, reducing the duration of the discharge phase of the power battery 210 and further improving the charging efficiency.

[0083] Alternatively, as Figure 6 As shown, the charging device 100 may further include an isolation unit 130 .

[0084] Specifically, the isolation unit 130 is connected between the N energy storage units and the power battery 210 . The isolation unit 130 includes M second DC / DC converters and a switch module 133 connected between the M second DC / DC converters. M is a positive integer greater than or equal to 2.

[0085] The control module 160 can control the switch module 133 to connect M second DC / DC converters in series. 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.

[0086] The control module 160 can also control the switch module 133 to connect M second DC / DC converters in parallel. At this time, 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.

[0087] Take M=2 as an example, Figure 6 As shown, isolation unit 130 includes two second DC / DC converters, namely, second DC / DC converter 131 and second DC / DC converter 132. When N energy storage units are charging power battery 210, the sides of second DC / DC converter 131 and second DC / DC converter 132 connected to the N energy storage units serve as input terminals, and the sides connected to power battery 210 serve as output terminals. The input terminals of second DC / DC converter 131 and second DC / DC converter 132 are connected in parallel, and a switch module 133 is connected between the output terminals of second DC / DC converter 131 and second DC / DC converter 132.

[0088] As an example, Figure 6As shown, the switch module 133 may include a switch K1, a switch K2, and a switch K3. When the energy storage unit 130 is charging the power battery 210, the control module 160 may control the switch K1 in the switch module 133 to close, thereby connecting the output terminals of the second DC / DC converter 131 and the second DC / DC converter 132 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.

[0089] When the energy storage unit 130 is charging the power battery 210, the control module 160 can control the switches K2 and K3 in the switch module 133 to connect the output terminals of the second DC / DC converter 131 and the second DC / DC converter 132 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.

[0090] As can be seen, since the isolation unit 130 is connected between the N energy storage units and the power battery 210, the isolation unit 130 includes M second DC / DC converters and a switch module 133 connected between the M second DC / DC converters. By controlling the switch module 133, the series-parallel connection relationship of the M second DC / DC converters at the output terminals can be changed, thereby adjusting the voltage output by the isolation unit 130 to the power battery 210. Specifically, when the switch module 133 of the isolation unit 130 is controlled to connect the M second DC / DC converters in series, high-voltage charging of the power battery 210 can be achieved. When the switch module 133 of the isolation unit 130 is controlled to connect the M second DC / DC converters in parallel, the currents output by the second DC / DC converters are added together, achieving high-current charging of the power battery 210.

[0091] Figure 7 Shown is based on Figure 4 The schematic flow chart of a possible implementation of the charging method shown in FIG. 1 is a flow chart showing a possible implementation of the charging method, wherein the power battery 210 is periodically charged and discharged to achieve rapid charging of the power battery 210. Figure 7 As shown, the method 70 may be executed by the control module 160, such as the EMS. Figure 5 Taking the charging device 100 shown as an example, the method 70 includes:

[0092] Step 701 : After detecting that the charging device 100 is successfully connected to the battery system 200 , charging of the power battery 210 is started.

[0093] 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.

[0094] Step 703 : Determine the output voltage of the first DC / DC converter in each energy storage unit and the output voltage of the AC / DC converter 140 .

[0095] The output voltage of the AC / DC converter 140 is equal to the charging voltage required by 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. This allows energy storage batteries with a high SOC to transfer more power to the power battery 210, while energy storage batteries with a low SOC transfer less power to the power battery 210. This avoids energy mismatch between different energy storage batteries and improves charging efficiency.

[0096] Step 704: Send a second control signal to the first DC / DC converter in each energy storage unit.

[0097] The 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 the second voltage through the first DC / DC converter in each energy storage unit.

[0098] While executing step 704 , in step 705 : a third control signal is sent to the AC / DC converter 140 .

[0099] The 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 the charging voltage.

[0100] Step 706: Determine whether charging is completed.

[0101] For example, when the voltage of the power battery 210 reaches the full charge voltage, the control module 160 receives a charge stop message from the BMS 220. If the charge stop message is received, the control module 160 determines that charging is complete, ends charging, and executes step 716. If the charge stop message is not received, the control module 160 determines that charging is not complete and executes step 707.

[0102] Step 707: Record the charging time and determine whether the preset charging time has been reached.

[0103] The preset charging time is the duration of the charging phase for charging the power battery 210 in each charging cycle. Correspondingly, the preset discharging time is the duration of the discharging phase for discharging the power battery 210 in each charging cycle. By alternating between the charging phase and the discharging phase, the power battery 210 is rapidly charged.

[0104] When the preset charging time has not been reached, the power battery 210 continues to be charged based on the above steps; when the preset charging time has been reached, the discharge phase of the charging cycle is entered.

[0105] 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.

[0106] Step 709 : Determine the output voltage of the first DC / DC converter in each energy storage unit and the output voltage of the AC / DC converter 140 .

[0107] 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. This allows energy storage batteries with a higher SOC to receive less power from the power battery 210, while energy storage batteries with a lower SOC receive more power from the power battery 210. This avoids energy mismatch between different energy storage batteries and improves charging efficiency.

[0108] Step 710: Send a first control signal to the first DC / DC converter in each energy storage unit.

[0109] 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 electricity released by the power battery 210 according to the first voltage through the first DC / DC converter in each energy storage unit.

[0110] While step 710 is being executed, in step 711 : it is determined whether the power battery 210 is allowed to discharge to the AC power source 150 .

[0111] If the power battery 210 is not allowed to discharge into the AC power source 150 , execute step 712 ; otherwise, execute step 713 .

[0112] Step 712 : Send a stop signal to the AC / DC converter 140 .

[0113] The stop signal is used to control the AC / DC converter 140 to shut down.

[0114] Step 713 : Send a third control signal to the AC / DC converter 140 .

[0115] The 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 supply 150 receives the power released by the power battery 210 according to the discharge voltage.

[0116] Step 714: Determine whether charging is completed.

[0117] For example, when the voltage of power battery 210 reaches the full charge voltage, control module 160 receives a charge stop message from BMS 220. If a charge stop message is received, charging is determined to be complete, and the process ends, executing step 716. If no charge stop message is received, charging is determined to be incomplete, and the process proceeds to step 715.

[0118] Step 715: Record the charging time and determine whether the preset discharge time has been reached.

[0119] The preset discharge time is the time of the discharge phase for discharging the power battery 210 in each charging cycle.

[0120] When the preset discharge time has not been reached, the power battery 210 continues to discharge to the N energy storage units based on the above steps; when the preset discharge time is reached, the charging phase of the next charging cycle is entered.

[0121] Step 716: Charging ends.

[0122] from Figure 7 It can be seen that the control module 160 can control the amount of electricity released or received by the energy storage unit in each energy storage unit by controlling the output voltage of each first DC / DC converter in the charging stage and the discharging stage, thereby avoiding energy mismatch between the energy storage units, achieving full utilization of each energy storage unit, and improving charging efficiency.

[0123] An embodiment of the present application further provides an EMS, comprising a processor, which is used to execute the charging method in the aforementioned embodiments of the present application.

[0124] The present application also provides a charging system, comprising: a power battery; and the charging device 100 described in any of the above embodiments. The charging device 100 is used to charge the power battery 210, wherein each charging cycle includes a charging phase for the power battery 210 and a discharging phase for the power battery 210.

[0125] It should be understood that the specific examples in this article are only intended to help those skilled in the art better understand the embodiments of the present application, and are not intended to limit the scope of the embodiments of the present application.

[0126] It should also be understood that in the various embodiments of the present application, the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0127] It should also be understood that the various implementation methods described in this specification can be implemented individually or in combination, and the embodiments of the present application are not limited to this.

[0128] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and components may be substituted with equivalents without departing from the scope of the present application. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions within the scope of the claims.

Claims

1. A method for charging a power battery, characterized in that: Applicable to a charging device, the charging device comprising N energy storage units connected in series, 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 a phase of charging the power battery and a phase of discharging the N energy storage units by the power battery, and fast charging of the power battery is achieved based on an alternating charge and discharge manner, where N is a positive integer greater than 1; The charging method includes: During the discharging phase, obtaining the current voltage of the energy storage battery in each energy storage unit; determining, according to the current voltage of the energy storage battery in each energy storage unit, a first voltage output by the first DC / DC converter in each energy storage unit, wherein 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; A first control signal is sent 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 the first voltage, so that the energy storage battery in each energy storage unit receives the electricity released by the power battery according to the first voltage through the first DC / DC converter in each energy storage unit.

2. The charging method according to claim 1, wherein: The method further comprises: During the charging phase, obtaining the current voltage of the energy storage battery in each energy storage unit; determining, according to the current voltage of the energy storage battery in each energy storage unit, a second voltage output by the first DC / DC converter 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; A second control signal is sent to the first DC / DC converter in each energy storage unit, where 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.

3. The charging method according to claim 1 or 2, characterized in that: The charging device further includes 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, where M is a positive integer greater than or equal to 2; The charging method further 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 switch module is controlled 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.

4. The charging method according to any one of claims 1 to 2, characterized in that: The charging device further includes an AC / DC converter connected between the power battery and an AC power source; The charging method further includes: A third control signal is sent to the AC / DC converter, where 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, so that the AC power supply charges the power battery according to the charging voltage through the AC / DC converter.

5. The charging method according to claim 4, characterized in that: The charging method further includes: A fourth control signal is sent to the AC / DC converter, where 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, so that the power battery discharges to the AC power supply through the AC / DC converter according to the discharge voltage.

6. A power battery charging device, characterized in that: The charging device includes N energy storage units connected in series and a control module, wherein each energy storage unit includes 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 stage of charging the power battery and a stage of discharging the N energy storage units by the power battery. Rapid charging of the power battery is achieved based on an alternating charging and discharging method, where N is a positive integer greater than 1. The control module is used for: During the discharging phase, obtaining the current voltage of the energy storage battery in each energy storage unit; determining, according to the current voltage of the energy storage battery in each energy storage unit, a first voltage output by the first DC / DC converter in each energy storage unit, wherein 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; A first control signal is sent 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 the first voltage, so that the energy storage battery in each energy storage unit receives the electricity released by the power battery according to the first voltage through the first DC / DC converter in each energy storage unit.

7. The charging device according to claim 6, characterized in that The control module is further configured to: During the charging phase, obtaining the current voltage of the energy storage battery in each energy storage unit; determining, according to the current voltage of the energy storage battery in each energy storage unit, a second voltage output by the first DC / DC converter 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; A second control signal is sent to the first DC / DC converter in each energy storage unit, where 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.

8. The charging device according to claim 6 or 7, characterized in that: The charging device further includes 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, where M is a positive integer greater than or equal to 2; The control module is further configured to: 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 The switch module is controlled 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 the current output by the N energy storage units.

9. The charging device according to any one of claims 6 to 7, characterized in that: The charging device further includes an AC / DC converter connected between the power battery and an AC power source; The control module is further configured to: A third control signal is sent to the AC / DC converter, where 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, so that the AC power supply charges the power battery according to the charging voltage through the AC / DC converter.

10. The charging device according to claim 9, characterized in that: The control module is further configured to: A fourth control signal is sent to the AC / DC converter, where 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, so that the power battery discharges to the AC power supply through the AC / DC converter according to the discharge voltage.

11. An EMS comprising a processor, wherein the processor is configured to execute the charging method according to any one of claims 1 to 5.

12. A charging system, characterized in that: include: Power batteries; The charging device according to any one of claims 6 to 10, wherein the charging device is used to charge the power battery, wherein each charging cycle includes a stage of charging the power battery and a stage of discharging the power battery.

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