Battery charging control method, energy storage device and photovoltaic energy storage system

Abstract

The present application provides a battery charging control method, energy storage equipment and photovoltaic energy storage system, wherein the method includes: when the battery is in a floating charge state, obtaining the actual charging voltage of the battery, the actual charging current of the battery, the actual charging power of the battery and the actual power generation voltage of the power generation module; obtaining a first adjustment parameter based on the actual charging voltage, the preset floating charge voltage of the battery and the actual charging current; obtaining a second adjustment parameter based on the actual charging power and the limit charging power of the battery; obtaining a target power generation voltage of the power generation module based on the first adjustment parameter, the second adjustment parameter and the actual power generation voltage of the power generation module; adjusting the actual power generation voltage of the power generation module based on the target power generation voltage to stabilize the floating charge state of the battery. Through the present application, the power generation voltage of the power generation module can be adjusted so that the battery can be stably float charged and the service life of the battery can be increased.

Description

Technical Field

[0001] The present application relates to the technical field of power supplies, and in particular to a battery charging control method, energy storage equipment and a photovoltaic energy storage system. Background Art

[0002] In a photovoltaic energy storage system, when the energy storage inverter is off-grid, the energy required by the load is provided by the PV (Photovoltaic) modules and batteries. If the load is not connected or the load is small, the power generated by the PV modules will be used to charge the battery, causing the battery to gradually fill up and even enter a floating charge state. When the battery enters a floating charge state, the charging voltage at the battery end needs to be kept constant to achieve a stable floating charge.

[0003] However, when the battery capacity is small, the charging voltage of the battery in the floating charge state is easily affected by the frequently changing PV power generation voltage, resulting in drastic and frequent fluctuations in the charging voltage, which not only affects the battery floating charge effect, but also damages the battery life. Summary of the invention

[0004] In view of the above, it is necessary to provide a battery charging control method and system thereof, which can adjust the power generation voltage of the power generation module so that the battery can be stably float charged and the battery life can be improved.

[0005] The first aspect of the present application provides a battery charging control method, in which the battery is connected to the output end of a power generation module, and the power generation module is used to charge the battery, including: when the battery is in a floating charge state, obtaining the actual charging voltage of the battery, the actual charging current of the battery, the actual charging power of the battery and the actual power generation voltage of the power generation module; obtaining a first adjustment parameter based on the actual charging voltage, a preset floating charge voltage of the battery and the actual charging current; obtaining a target power generation voltage of the power generation module based on the first adjustment parameter, the second adjustment parameter and the actual power generation voltage of the power generation module; and adjusting the actual power generation voltage of the power generation module based on the target power generation voltage to stabilize the floating charge state of the battery.

[0006] In some embodiments, based on the first adjustment parameter, the second adjustment parameter and the actual generation voltage of the generation module, the target generation voltage of the generation module is obtained, including: obtaining a control quantity based on the first adjustment parameter and the second adjustment parameter; adjusting the actual generation voltage of the generation module based on the control quantity to obtain the target generation voltage.

[0007] In some embodiments, the control amount is positively correlated with the first adjustment parameter, the control amount is positively correlated with the second adjustment parameter, and the control amount is negatively correlated with the target power generation voltage.

[0008] In some embodiments, obtaining a control quantity based on a first adjustment parameter and a second adjustment parameter includes: when the second adjustment parameter is greater than 0, setting the second adjustment parameter to zero, and obtaining the control quantity based on the first adjustment parameter; or, when the second adjustment parameter is equal to 0, obtaining the control quantity based on the first adjustment parameter; or, when the second adjustment parameter is less than 0, obtaining the control quantity based on the first adjustment parameter and the second adjustment parameter.

[0009] In some embodiments, adjusting the actual power generation voltage of the power generation module based on the control amount to obtain the target power generation voltage includes: subtracting a preset proportion of the control amount from the actual power generation voltage of the power generation module to obtain the target power generation voltage.

[0010] In some embodiments, a first adjustment parameter is obtained based on the actual charging voltage, the preset floating charge voltage of the battery and the actual charging current, including: calculating the voltage difference between the actual charging voltage of the battery and the preset floating charge voltage of the battery; multiplying the voltage difference by the actual charging current of the battery to obtain the first adjustment parameter.

[0011] In some embodiments, a first adjustment parameter is obtained based on the actual charging voltage, the preset floating charge voltage of the battery and the actual charging current, including: calculating the voltage difference between the actual charging voltage of the battery and the preset floating charge voltage of the battery; multiplying the voltage difference with the actual charging current of the battery to obtain a calculation result; and performing a deviation adjustment on the deviation of the calculation result to obtain the first adjustment parameter.

[0012] In some embodiments, obtaining a second adjustment parameter based on the actual charging power and a preset limit charging power of the battery includes: calculating a power difference between the actual charging power and the limit charging power, and using the power difference as the second adjustment parameter.

[0013] In some embodiments, a second adjustment parameter is obtained based on the actual charging power and the preset limit charging power of the battery, including: calculating the power difference between the actual charging power and the limit charging power; performing deviation adjustment on the power difference, and obtaining the second adjustment parameter through the deviation adjustment.

[0014] The second aspect of the present application provides an energy storage device, which includes: a battery, a power conversion circuit and a controller, the battery and the controller are respectively connected to the power conversion circuit, and the power conversion circuit is also connected to the photovoltaic power generation component; the power conversion circuit is used to convert the power generation voltage output by the photovoltaic power generation component and charge the battery; the controller is used to obtain a target power generation voltage of the photovoltaic power generation component based on the actual charging voltage of the battery, the actual charging current of the battery, the actual charging power of the battery and the actual power generation voltage of the photovoltaic power generation component when the battery is in a floating charge state, and adjust the actual power generation voltage of the photovoltaic power generation component based on the target power generation voltage to stabilize the floating charge state of the battery.

[0015] In some embodiments, the energy storage device also includes an energy storage inverter, one end of the energy storage inverter is connected to the power conversion circuit, and the other end of the energy storage inverter is used to connect to the power grid. The controller is used to control the power conversion circuit to convert the power generation voltage output by the photovoltaic power generation component and then charge the battery when the energy storage inverter is in an off-grid operation state.

[0016] The third aspect of the present application provides a photovoltaic energy storage system, which includes: an energy storage device, a photovoltaic power generation component, a power grid and a load; the energy storage device includes: a battery, a power conversion circuit and a controller, the battery and the controller are respectively connected to the power conversion circuit, and the power conversion circuit is also connected to the photovoltaic power generation component; the power conversion circuit is used to convert the power generation voltage output by the photovoltaic power generation component and charge the battery; the controller is used to obtain a target power generation voltage of the photovoltaic power generation component based on the actual charging voltage of the battery, the actual charging current of the battery, the actual charging power of the battery and the actual power generation voltage of the photovoltaic power generation component when the battery is in a floating charge state, and adjust the actual power generation voltage of the photovoltaic power generation component based on the target power generation voltage to keep the battery in a floating charge state.

[0017] Compared with the prior art, this application has at least the following advantages:

[0018] 1. In the battery charging control method of the present application, whether the charging voltage of the battery is stable is related to the power generation voltage of the power generation module. First, multiple adjustment parameters are obtained, and the multiple adjustment parameters are related to the voltage and power of the battery to be float-charged. Then, the multiple adjustment parameters are calculated and coupled to obtain the control quantity for adjusting the power generation voltage of the power generation module, and the power generation voltage is adjusted based on the control quantity, thereby forming a multi-loop closed-loop control including a voltage loop and a power loop, and improving the dynamic response speed of adjusting the power generation voltage of the power generation module. The battery charging control method of the present application can adjust the power generation voltage of the power generation module so that the battery can be stably float-charged and the service life of the battery can be improved.

[0019] 2. The energy storage device and photovoltaic energy storage system of the present application can adjust the power generation voltage of the photovoltaic power generation component so that the battery can be stably float charged and the service life of the battery can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of the photovoltaic energy storage system of an embodiment of the present application.

[0021] Figure 2 It is a functional relationship diagram of the limit charging power of the battery of the embodiment of the present application and the actual charging voltage of the battery.

[0022] Figure 3 It is a flow chart of a battery charging control method according to an embodiment of the present application.

[0023] Figure 4 It is a sub-flowchart of step S400 of an embodiment of the present application.

[0024] Figure 5 This is a schematic diagram of the principle of obtaining the control quantity in step S400 of an embodiment of the present application.

[0025] Main component symbols

[0026] 1. Energy storage device; 11. Battery; 12. Power conversion circuit; 121. DC / DC conversion circuit; 122. BOOST circuit; 13. Energy storage inverter; 14. Controller; 2. Photovoltaic power generation component; 3. Power grid.

[0027] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only embodiments of a part of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present application. In the absence of conflict, the following different embodiments and features in the embodiments can be combined with each other.

[0029] In the description of the embodiments of the present application, words such as "exemplary", "or", "for example" and the like are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary", "or", "for example" and the like is intended to present related concepts in a concrete manner.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by technicians in the technical field in this application. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. It should be understood that, unless otherwise specified in this application, " / " means or. For example, A / B can represent A or B. "And / or" in this application is only a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. "At least one" means one or more. "Multiple" means two or more than two. For example, at least one of a, b or c can represent: a, b, c, a and b, a and c, b and c, a, b and c seven situations.

[0031] It should also be noted that the terms "first" and "second" in the specification, claims and drawings of this application are used to distinguish similar objects, rather than to describe a specific order or sequence. The method disclosed in the embodiments of this application or the method shown in the flowchart includes one or more steps for implementing the method. Without departing from the scope of the claims, the execution order of multiple steps can be interchanged with each other, and some steps can also be deleted.

[0032] Some embodiments will be described below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0033] Figure 1 1 is a structural diagram of a photovoltaic energy storage system 100 according to an embodiment of the present application. Figure 1 As shown, the photovoltaic energy storage system 100 may include: an energy storage device 1 and a photovoltaic power generation component 2. The energy storage device 1 includes: a battery 11, a power conversion circuit 12, an energy storage inverter 13 and a controller 14. The power conversion circuit 12 may include a DC / DC conversion circuit 121 and a BOOST circuit 122.

[0034] Specifically, the output end of the photovoltaic power generation component 2 is connected to the DC end of the energy storage inverter 13 through the BOOST circuit 122, the positive and negative electrodes of the battery 11 are connected to the DC end of the energy storage inverter 13 through the DC / DC conversion circuit 121, and the AC end of the energy storage inverter 13 is connected to the power grid 3 and the load 4. Among them, a grid-connected switch S1 can be set between the energy storage inverter 13 and the power grid 3. When the grid-connected switch S1 is turned on, the energy storage inverter 13 can be in a grid-connected state, and when the grid-connected switch S1 is turned off, the energy storage inverter 13 can be in an off-grid state. A load switch S2 can be set between the energy storage inverter 13 and the load. When the load switch S2 is turned on, the energy storage inverter 13 can be loaded, and when the load switch S2 is turned off, the energy storage inverter 13 is not loaded. The photovoltaic power generation component 2 is used as a power generation module, which can be used to convert solar energy into electrical energy and then transmit it to the energy storage inverter 13 through the BOOST circuit 122. The energy storage inverter 13 can then transmit the electrical energy to the load 4 and / or the power grid 3. The BOOST circuit 122 can be used as a maximum power point tracking circuit. When the load 4 is light and the photovoltaic power generation voltage exceeds the load 4 requirement, or when the load 4 is not connected, the electrical energy generated by the photovoltaic power generation component 2 can also be processed by the DC / DC circuit 121 to meet the charging specifications of the battery 11 and then transmitted to the battery 11, so that the battery 11 can be charged. The controller 14 can serve as the control center of the system, which can control the output of the photovoltaic power generation component 2, the charging and discharging of the battery 11, and the working condition of the power conversion circuit 12.

[0035] In the process of charging the battery 11, when the energy storage inverter 13 is in an off-grid operation state, the battery 11 can enter a floating charge state after being fully charged. In the floating charge state, it is necessary to provide a constant floating charge voltage and a very small floating charge current to the battery 11 to compensate for the self-discharge loss of the battery 11 and keep the battery 11 in a fully charged state. Therefore, when the battery 11 is in a floating charge state, it is necessary to keep the charging voltage of the battery 11 constant to achieve a voltage-stabilized floating charge, that is, to stabilize the floating charge state of the battery 11.

[0036] Since the floating charge state of the battery 11 requires the charging voltage to be slightly higher than the battery voltage, and the floating charge process of the battery 11 is usually performed at the limit charging power, when the charging voltage is large, the limit charging power of the battery 11 will decrease. Therefore, the stable floating charge state can mean that the minimum value in the fluctuation range of the charging voltage of the battery 11 is greater than the voltage of the battery 11 and the maximum value cannot exceed the voltage of the battery 11 charged at the limit charging power. For example, a 48V battery may enter the overvoltage protection stage when the charging voltage is above 54V and cannot be float charged. Therefore, the charging voltage of the battery 11 is set in the range of 48V to 54V, such as 52V, to achieve a stable floating charge state.

[0037] When the energy storage inverter 13 is connected to the grid, that is, when the grid switch S1 and the load switch S2 are both closed, the electric energy generated by the photovoltaic power generation assembly 2 can flow into the grid 3, can be used by the load 4, and can also be stored in the battery 11. When the energy storage inverter 13 is off the grid and the load 4 is light (equivalent to no load, the load switch S2 is disconnected), since the electric energy generated by the photovoltaic power generation assembly 2 can only be used to store in the battery 11, the charging voltage of the battery 11 will be easily affected by the photovoltaic power generation assembly 2. For example, when the capacity of the battery 11 is small, when the weather conditions suddenly change and the power generation voltage of the photovoltaic power generation assembly 2 changes frequently, the charging voltage of the battery 11 will fluctuate frequently following the frequently changing power generation voltage of the photovoltaic power generation assembly 2.

[0038] Figure 2 is a functional relationship diagram of the limit charging power of the battery 11 and the actual charging voltage of the battery 11 according to the embodiment of the present application. Figure 2 The maximum charging power of the battery 11 refers to the maximum charging power allowed when the battery 11 is charged. P batchrglmt ) and the actual charging voltage of the battery 11 ( v bat ) is related, and the correlation can be expressed as a function f ( v bat), this correlation can be regarded as the inherent performance of battery 11, which is set by the factory. When the actual charging voltage of battery 11 is relatively small, battery 11 can be stably float-charged at the limit charging power. When the actual charging voltage is relatively large, the limit charging power drops rapidly, and the float charging condition is not met. Therefore, when the charging voltage of battery 11 fluctuates frequently, it will affect the float charging effect of battery 11. It may even damage the service life of battery 11.

[0039] To this end, in the embodiment of the present application, the controller 14 of the energy storage device 1 can be used to execute the battery charging control method provided in the embodiment of the present application, by adjusting the actual power generation voltage of the photovoltaic power generation component 2 during the battery floating charge process, thereby reducing the fluctuation of the charging voltage, so that the battery 11 can be stably in a floating charge state, which is beneficial to protecting the battery 11. It can be understood that in the above-mentioned off-grid situation, the actual charging voltage of the battery 11 is directly related to the actual power generation voltage of the photovoltaic power generation component 2, so the actual charging voltage of the battery 11 can be adjusted by adjusting the actual power generation voltage of the photovoltaic power generation component 2.

[0040] In some embodiments, the actual charging voltage of the battery 11 may be the same as the actual power generation voltage of the photovoltaic power generation assembly 2, that is, the electric energy of the photovoltaic power generation assembly 2 may be directly used to charge the battery 11 without passing through the power conversion circuit 12. In other words, in the embodiment of the present application, the actual power generation voltage of the photovoltaic power generation assembly 2 may be directly controlled so that the battery 11 may be stably in a floating charge state.

[0041] In other embodiments, the actual charging voltage of the battery 11 may be proportional to the actual power generation voltage of the photovoltaic power generation assembly 2, and therefore, the actual power generation voltage of the photovoltaic power generation assembly 2 may be converted into the actual charging voltage of the battery 11 by the power conversion circuit 12 to charge the battery 11. In other words, in the embodiment of the present application, the actual power generation voltage of the photovoltaic power generation assembly 2 may be controlled, and then the actual charging voltage of the battery 11 may be controlled, so that the battery 11 may be stably in a floating charge state.

[0042] In the process of converting the actual power generation voltage of the photovoltaic power generation component 2 into the actual charging voltage of the battery 11 by the power conversion circuit 12 and then charging the battery 11, since the voltage regulation of the power conversion circuit 12 may have upper and lower limits, that is, the actual power generation voltage of the photovoltaic power generation component 2 connected to its input side fluctuates too much and may exceed the regulation range of the power conversion circuit 12, resulting in the regulated voltage not being within the floating charge voltage threshold range of the battery 11. Therefore, the embodiment of the present application preferably directly controls the actual power generation voltage of the photovoltaic power generation component 2 so that the battery 11 can be stably in a floating charge state.

[0043] Figure 3 FIG. 1 is a flow chart of a battery charging control method according to an embodiment of the present application. Figure 3As shown, the charging control method may include:

[0044] Step S100: when the battery is in a floating charge state, obtaining the actual charging voltage of the battery, the actual charging current of the battery, the actual charging power of the battery and the actual power generation voltage of the power generation module.

[0045] The actual charging voltage of the battery refers to the actual voltage of the battery in the floating charge state ( v bat ), the actual charging current of the battery refers to the actual current of the battery in the floating charge state ( i bat ), the actual charging power of the battery refers to the actual power of the battery in the floating charge state ( P batreal ), the actual power generation voltage of the power generation module refers to the actual power generation voltage of the power generation module under various weather conditions ( v pvreal ).

[0046] It should be understood that Figure 1 In the scenario shown, the power generation module in the method of the embodiment of the present application refers to a photovoltaic power generation component. Figure 1 When the photovoltaic power generation components in the scenario shown are replaced with other devices or equipment with power generation capabilities, such as wind power generation devices, hydropower generation devices, etc., the power generation module in the embodiment method of the present application refers to wind power generation devices, hydropower generation devices, etc.

[0047] Step S200: Obtain a first adjustment parameter based on the actual charging voltage, the preset floating charging voltage of the battery, and the actual charging current.

[0048] The preset floating charge voltage of the battery refers to the reference voltage when the battery is in a stable floating charge state ( v batfloatset ).

[0049] In some embodiments, step S200 may specifically include:

[0050] Calculate the voltage difference between the actual charging voltage of the battery and the preset floating charging voltage of the battery.

[0051] The voltage difference is multiplied by the actual charging current of the battery to obtain a first adjustment parameter.

[0052] It can be understood that the actual charging voltage of the battery is positively correlated with the actual power generation voltage of the power generation module. The greater the actual power generation voltage of the power generation module, the greater the actual charging voltage of the battery. Conversely, the smaller the actual power generation voltage of the power generation module, the smaller the actual charging voltage of the battery. Therefore, the voltage difference between the actual charging voltage of the battery and the preset floating charge voltage of the battery is calculated, and then adjusted through the proportional relationship, which can be used to feed back to the power generation module to adjust the actual power generation voltage (i.e., adjust the power generation voltage), thereby adjusting the battery charging voltage to the preset floating charge voltage, that is, entering a stable floating charge state.

[0053] It should be understood that in step S200, the first adjustment parameter obtained by multiplying the voltage difference by the actual charging current of the battery is essentially a power parameter, and thus can be used in subsequent power loop adjustment.

[0054] In other embodiments, Figure 5 As shown, step S200 may specifically include:

[0055] Calculate the voltage difference between the actual charging voltage of the battery and the preset floating charging voltage of the battery;

[0056] The voltage difference is multiplied by the actual charging current of the battery to obtain a calculation result, and the calculation result is subjected to deviation adjustment to obtain a first adjustment parameter.

[0057] Among them, deviation regulation includes one of proportional (P) regulation, integral regulation (I), differential regulation (D), proportional integral (PI) regulation, proportional differential (PD) regulation and proportional integral differential (PID) regulation. For the convenience of description, Figure 5 In the example, the deviation regulation is demonstrated by using PI regulation. It can be understood that the deviation regulation can improve the accuracy of the parameters and help to accurately adjust the power generation voltage of the power generation module.

[0058] It can be understood that in step S200, whether the battery is currently in a stable floating charging state can be known through the actual charging voltage of the battery, and the first adjustment parameter of the battery voltage parameter that feeds back the current state can be obtained. The first adjustment parameter can be used to adjust the power generation voltage of the power generation module, that is, voltage loop control can be formed through the first adjustment parameter.

[0059] Step S300: Obtain a second adjustment parameter based on the actual charging power and the limit charging power of the battery.

[0060] In some embodiments, step S300 may specifically include:

[0061] The power difference between the actual charging power and the limit charging power is calculated to obtain a second adjustment parameter.

[0062] It is understandable that when the actual charging voltage of the battery changes, the power of the battery will also change under the influence of the actual charging voltage. Since power is the product of voltage and current, the power change amplitude can be greater than the voltage change amplitude, and the battery power change is more obvious, that is, the power sensitivity of the battery is higher than the voltage sensitivity. Therefore, by calculating the power difference between the actual charging power and the limit charging power, and then adjusting it through the proportional relationship, it can be used to feed back to the power generation module to adjust the actual power generation power or the actual power generation voltage (that is, adjust the power generation voltage), and the adjustment sensitivity is better and the response speed is higher. At the same time, combined with the voltage loop adjustment, the dynamic response can be further effectively improved.

[0063] Figure 4 It is a sub-flowchart of step S400 of an embodiment of the present application. Figure 5 This is a schematic diagram of the principle of obtaining the control quantity in step S400 of an embodiment of the present application.

[0064] In other embodiments, Figure 5 As shown, step S300 may specifically include:

[0065] The power difference between the actual charging power and the limit charging power is calculated, and the power difference is deviation-adjusted to obtain a second adjustment parameter.

[0066] The deviation adjustment may refer to the related description of the previous step S200, which will not be repeated here. Figure 5 In the figure, the deviation adjustment using P adjustment is demonstrated as an example.

[0067] From step S300, it can be known whether the battery is currently in a stable floating charging state, and the second adjustment parameter of the battery power parameter that feeds back the current state can be obtained. The first adjustment parameter can be used to adjust the power generation voltage of the power generation module, that is, power loop control can be formed through the second adjustment parameter.

[0068] Step S400: obtaining a target power generation voltage of the power generation module based on the first adjustment parameter, the second adjustment parameter and the actual power generation voltage of the power generation module.

[0069] In some embodiments, see Figure 4 and Figure 5 Step S400 may specifically include:

[0070] Step S401: Obtain a control amount based on a first adjustment parameter and a second adjustment parameter.

[0071] It can be understood that the controller 14 is associated with the first adjustment parameter and the second adjustment parameter, so the control amount can be obtained by coupling calculation according to the first adjustment parameter and the second adjustment parameter. For example, in some embodiments, the first adjustment parameter and the control amount can be positively correlated, the second adjustment parameter and the control amount can be positively correlated, and the control amount and the target power generation voltage can be negatively correlated.

[0072] Further example, in one embodiment, the first adjustment parameter v 1 , the second adjustment parameter v 2 , control amount v There is a correlation relationship as shown in the following expression:

[0073] (1)

[0074] Among them, the function sgn(v2) is a symbolic function that satisfies:

[0075] (2)

[0076] Therefore, in step S401, in the second adjustment parameter v 2 When is equal to 0, formula (1) is v = v 1 +0, that is, the control amount is equal to the first adjustment parameter v 1 , which is equivalent to adjusting the first parameter v 1 Calculate the control amount v , that is, the floating charge state of the battery is maintained only by the regulation of the battery voltage loop. This is because, under normal circumstances where the battery is in a steady-state floating charge, the output of the battery power loop will not affect the control quantity. v The battery can be kept in floating charge state only by regulating the battery voltage loop. v 2 Equal to 0 can be understood as the critical point of steady-state floating charge.

[0077] When the battery is in a steady state floating charge and is not close to the critical point, it can also be understood that the output of the battery power loop will not affect the control quantity. v The battery voltage loop can be used to adjust the battery to maintain the floating charge state. v 2 Set to greater than 0, function sgn ( v 2) is output as 1, or the second adjustment parameter v 2 Set to 0 and set the first adjustment parameter v 1 and the second adjustment parameter set to 0 v 2 Substituting into formula (1), we can get the control quantity v It should be understood that this is equivalent to adjusting the first parameter v 1 Calculate the control amount v .

[0078] When the battery is in an unsteady floating state, the output of the battery power loop will v The battery voltage loop and power loop need to be regulated to maintain the floating charge state of the battery. v 2 Set to less than 0, through the function sgn ( v 2 ) The second adjustment parameter in formula (1) v 2 The coefficient (1- sgn ( v 2 )) / 2 is set to 1, at this time the second adjustment parameter v 2 Participate in the calculation, based on the first adjustment parameter v 1 and the second adjustment parameter v 2 The control quantity is obtained. That is, the floating charge state of the battery is maintained through the regulation of the battery voltage loop and the power loop. This is mainly due to the fact that when the power generation voltage of the power generation module changes drastically and causes the battery charging power to exceed its limit charging power, the regulation of the power loop also starts to work. Accordingly, the second regulation parameter v 2 Will control the amount v This can have an impact, thereby accelerating the adjustment process of the power generation module, thereby accelerating the steady state under dynamic changes to enter the stable floating charging process.

[0079] It can be seen that step S400 can be based on the first adjustment parameter v 1 and the second adjustment parameter v 2 Determine whether the battery is in a stable floating charge state, and select voltage loop control or power loop control according to the state to adjust the power generation voltage of the power generation module. For example, select voltage loop control during stable floating charge, and select voltage loop control and power loop control together during unstable floating charge to improve dynamic response speed.

[0080] Step S402: Based on the control amount v The actual power generation voltage of the power generation module is adjusted to obtain the target power generation voltage of the power generation module.

[0081] In some embodiments, step S402 may include:

[0082] The target power generation voltage of the power generation module is obtained by subtracting the preset proportion of the control amount from the actual power generation voltage of the power generation module. Specifically, the relationship between the actual power generation voltage of the power generation module and the target power generation voltage can be expressed as the following expression:

[0083] (3)

[0084] in, v pvref , v pvreal They are the target power generation voltage and actual power generation voltage of the power generation module. k p is the adjustment coefficient. In some embodiments, the adjustment coefficient can be set according to the capacity of the battery or power generation system. For example, it can be set to a fixed coefficient of 0.5, 1, 1.5, etc.

[0085] Therefore, by substituting the actual power generation voltage of the power generation module into equation (3), the target power generation voltage of the power generation module can be calculated.

[0086] Step S500: adjusting the actual power generation voltage of the power generation module based on the target power generation voltage to keep the battery in a floating charge state.

[0087] In other embodiments, the control amount v It can also be used to adjust the power generation of the power generation module. The power generation is the product of the power generation voltage and current. Therefore, by controlling the amount v The process of adjusting the power generation of the power generation module is basically similar to the process of adjusting the power generation voltage of the power generation module mentioned above, and will not be elaborated here.

[0088] In summary, in the charging control method of the battery in the embodiment of the present application, a plurality of adjustment parameters are first obtained, and the plurality of adjustment parameters are related to the voltage and power of the battery to be float-charged, and then the plurality of adjustment parameters are calculated and coupled to obtain a control quantity for adjusting the power generation voltage, and the power generation voltage is adjusted based on the control quantity, so that the battery can be stably float-charged and the service life of the battery is improved. Moreover, this control process is a multi-loop closed-loop control process including a voltage loop and a power loop, which can effectively improve the dynamic response speed of adjusting the power generation voltage of the power generation module, and is more conducive to the stable float charge of the battery.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application and are not intended to limit it. Although the present application has been described in detail with reference to the preferred embodiments, a person of ordinary skill in the art should understand that the technical solution of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present application.

Claims

1. A battery charging control method, wherein the battery is connected to an output end of a power generation module, and the power generation module is used to charge the battery, characterized in that: include: When the battery is in a floating charge state, obtaining an actual charging voltage of the battery, an actual charging current of the battery, an actual charging power of the battery, and an actual power generation voltage of the power generation module; obtaining a first adjustment parameter based on the actual charging voltage, a preset floating charge voltage of the battery, and the actual charging current; Based on the actual charging power and the limit charging power of the battery, a second regulating parameter is obtained; based on the first regulating parameter, the second regulating parameter and the actual power generation voltage of the power generation module, a target power generation voltage of the power generation module is obtained; based on the target power generation voltage, the actual power generation voltage of the power generation module is adjusted to keep the battery in a floating charge state; wherein, based on the first regulating parameter, the second regulating parameter and the actual power generation voltage of the power generation module, the target power generation voltage of the power generation module is obtained, including: obtaining a control amount based on the first regulating parameter and the second regulating parameter, wherein when the second regulating parameter is greater than 0, the second regulating parameter is set to zero, and based on the first The control amount is obtained by adjusting the parameter, or, when the second adjustment parameter is equal to 0, the control amount is obtained based on the first adjustment parameter, or when the second adjustment parameter is less than 0, the control amount is obtained based on the first adjustment parameter and the second adjustment parameter; the actual power generation voltage of the power generation module is subtracted from the preset proportion of the control amount to obtain the target power generation voltage; wherein the first adjustment parameter is used to feed back the battery voltage parameter of the current state, the second adjustment parameter is used to feed back the battery power parameter of the current state, the control amount is positively correlated with the first adjustment parameter, the control amount is positively correlated with the second adjustment parameter, and the control amount is negatively correlated with the target power generation voltage.

2. The battery charging control method according to claim 1, characterized in that: The first adjustment parameter is obtained based on the actual charging voltage, the preset floating charge voltage of the battery and the actual charging current, including: calculating the voltage difference between the actual charging voltage of the battery and the preset floating charge voltage of the battery; multiplying the voltage difference with the actual charging current of the battery to obtain the first adjustment parameter.

3. The battery charging control method according to claim 1, characterized in that: The first adjustment parameter is obtained based on the actual charging voltage, the preset floating charge voltage of the battery and the actual charging current, including: calculating the voltage difference between the actual charging voltage of the battery and the preset floating charge voltage of the battery; multiplying the voltage difference with the actual charging current of the battery to obtain a calculation result; and performing deviation adjustment on the calculation result to obtain the first adjustment parameter.

4. The battery charging control method according to claim 1, characterized in that: The obtaining of the second adjustment parameter based on the actual charging power and the preset limit charging power of the battery includes: calculating a power difference between the actual charging power and the limit charging power, and using the power difference as the second adjustment parameter.

5. The battery charging control method according to claim 1, characterized in that: The obtaining of the second adjustment parameter based on the actual charging power and the preset limit charging power of the battery includes: calculating the power difference between the actual charging power and the limit charging power; performing deviation adjustment on the power difference, and obtaining the second adjustment parameter through the deviation adjustment.

6. An energy storage device, characterized in that: The energy storage device includes: a battery, a power conversion circuit and a controller, the battery and the controller are respectively connected to the power conversion circuit, and the power conversion circuit is also connected to a photovoltaic power generation component; the power conversion circuit is used to convert the power generation voltage output by the photovoltaic power generation component and charge the battery; the controller is used to obtain the target power generation voltage of the photovoltaic power generation component based on the actual charging voltage of the battery, the actual charging current of the battery, the actual charging power of the battery and the actual power generation voltage of the photovoltaic power generation component when the battery is in a floating charge state, and adjust the actual power generation voltage of the photovoltaic power generation component based on the target power generation voltage to keep the battery in a floating charge state, including: when the battery is in a floating charge state, obtaining the actual charging voltage of the battery, the actual charging current of the battery, the actual charging power of the battery and the actual power generation voltage of the power generation module; obtaining a first adjustment parameter based on the actual charging voltage, the preset floating charge voltage of the battery and the actual charging current; obtaining a second adjustment parameter based on the actual charging power and the limit charging power of the battery; obtaining a maximum value of the ... The method comprises: obtaining a target power generation voltage of the power generation module; adjusting the actual power generation voltage of the power generation module based on the target power generation voltage so that the battery maintains a floating charge state; wherein, obtaining the target power generation voltage of the power generation module based on the first adjustment parameter, the second adjustment parameter and the actual power generation voltage of the power generation module comprises: obtaining a control amount based on the first adjustment parameter and the second adjustment parameter, wherein when the second adjustment parameter is greater than 0, the second adjustment parameter is set to zero, and the control amount is obtained based on the first adjustment parameter, or, when the second adjustment parameter is equal to 0, the control amount is obtained based on the first adjustment parameter, or, when the second adjustment parameter is less than 0, the control amount is obtained based on the first adjustment parameter and the second adjustment parameter; subtracting a preset proportion of the control amount from the actual power generation voltage of the power generation module to obtain the target power generation voltage; wherein, the first adjustment parameter is used to feedback the battery voltage parameter of the current state, the second adjustment parameter is used to feedback the battery power parameter of the current state, the control amount is positively correlated with the first adjustment parameter, the control amount is positively correlated with the second adjustment parameter, and the control amount is negatively correlated with the target power generation voltage.

7. The energy storage device according to claim 6, characterized in that: The energy storage device also includes an energy storage inverter, one end of which is connected to the power conversion circuit, and the other end of which is used to connect to the power grid. The controller is used to control the power conversion circuit to convert the power generation voltage output by the photovoltaic power generation component and then charge the battery when the energy storage inverter is in an off-grid operation state.

8. A photovoltaic energy storage system, characterized in that: The photovoltaic energy storage system includes: an energy storage device, a photovoltaic power generation component, a power grid and a load; the energy storage device includes: a battery, a power conversion circuit and a controller, the battery and the controller are respectively connected to the power conversion circuit, and the power conversion circuit is also connected to the photovoltaic power generation component; the power conversion circuit is used to convert the power generation voltage output by the photovoltaic power generation component and charge the battery; the controller is used to obtain the target power generation voltage of the photovoltaic power generation component based on the actual charging voltage of the battery, the actual charging current of the battery, the actual charging power of the battery and the actual power generation voltage of the photovoltaic power generation component when the battery is in a floating charge state, and adjust the actual power generation voltage of the photovoltaic power generation component based on the target power generation voltage to keep the battery in a floating charge state, including: when the battery is in a floating charge state, obtaining the actual charging voltage of the battery, the actual charging current of the battery, the actual charging power of the battery and the actual power generation voltage of the power generation module; obtaining a first adjustment parameter based on the actual charging voltage, the preset floating charge voltage of the battery and the actual charging current; obtaining a second adjustment parameter based on the actual charging power and the limit charging power of the battery; obtaining a second adjustment parameter based on the first adjustment parameter, the second adjustment parameter and The actual power generation voltage of the power generation module is used to obtain the target power generation voltage of the power generation module; the actual power generation voltage of the power generation module is adjusted based on the target power generation voltage to keep the battery in a floating charge state; wherein, the target power generation voltage of the power generation module is obtained based on the first adjustment parameter, the second adjustment parameter and the actual power generation voltage of the power generation module, including: obtaining a control amount based on the first adjustment parameter and the second adjustment parameter, wherein when the second adjustment parameter is greater than 0, the second adjustment parameter is set to zero, and the control amount is obtained based on the first adjustment parameter, or, when the second adjustment parameter is equal to 0, the control amount is obtained based on the first adjustment parameter, or, when the second adjustment parameter is less than 0, the control amount is obtained based on the first adjustment parameter and the second adjustment parameter; the actual power generation voltage of the power generation module is subtracted from the control amount of a preset proportion to obtain the target power generation voltage; wherein, the first adjustment parameter is used to feedback the battery voltage parameter of the current state, the second adjustment parameter is used to feedback the battery power parameter of the current state, the control amount is positively correlated with the first adjustment parameter, the control amount is positively correlated with the second adjustment parameter, and the control amount is negatively correlated with the target power generation voltage.

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