Charging control method of power supply circuit, power supply device and energy storage device

Abstract

The application provides a charging control method of a power supply circuit, a power supply device and an energy storage device. The power supply circuit is arranged in a power supply system including a battery pack, a direct-current power generation device, an inverter and the power supply circuit. The method comprises the following steps: in each operation period, obtaining reserved power of the inverter in a previous operation period, actual power generation of the direct-current power generation device and a power fluctuation coefficient; determining the reserved power in the current operation period according to the reserved power in the previous operation period and the power fluctuation coefficient; determining an upper limit of charging power according to the actual power generation and the reserved power in the current operation period; performing amplitude limiting processing on a target charging power of the power supply circuit according to the upper limit of the charging power; and obtaining electric energy from a direct-current bus to charge the battery pack according to the target charging power after the amplitude limiting processing. The method provided by the application can update the reserved power according to different inverters and different working conditions, so that the normal operation of the inverter is ensured when the battery pack is charged.

Description

Technical Field

[0001] This application relates to the field of electronic equipment technology, and in particular to a charging control method for a power supply circuit, a power supply device, and an energy storage device. Background Technology

[0002] Photovoltaic power generation technology is a technology that converts solar energy into electrical energy to power loads. In related technologies, in order to make full use of solar energy resources, photovoltaic systems use inverters to convert the direct current generated by photovoltaic modules into alternating current for the load. At the same time, photovoltaic systems also use energy storage devices to store excess energy supplied by photovoltaic modules to the load, so that when solar energy resources are insufficient, the energy storage devices can be controlled to provide energy to the load through the photovoltaic inverter.

[0003] In this photovoltaic system, when the energy storage device is charged to store the energy generated by the photovoltaic modules, a certain amount of reserved power is required to maintain the basic operation of the inverter, such as achieving maximum power point tracking (MPPT). However, the reserved power may differ for different inverters. Even for the same inverter, the reserved power will vary under different voltage and current conditions. Related technologies typically employ a single reserved power. This leads to power waste when the reserved power is too high, and instability in certain inverters or under certain operating conditions when the reserved power is too low, thus exacerbating voltage fluctuations in the photovoltaic modules. Summary of the Invention

[0004] In view of this, this application provides a charging control method for a power supply circuit, a power supply device, and an energy storage device, which can be adapted to different inverters and different operating conditions to update the reserved power, thereby ensuring the normal operation of the inverter when charging the battery pack.

[0005] The first aspect of this application provides a charging control method for a power supply circuit. The power supply circuit is disposed in a power supply system, which includes a battery pack, a DC power generation device, an inverter, and the power supply circuit. A first terminal of the power supply circuit is used to connect to the battery pack. A second terminal of the power supply circuit, the output terminal of the DC power generation device, and the DC input terminal of the inverter are all connected to a DC bus. The method includes: in each operating cycle, acquiring the reserved power of the inverter in the previous operating cycle, the actual power generation of the DC power generation device, and the power fluctuation coefficient; the power fluctuation coefficient is used to characterize the degree of fluctuation of the actual power generation; determining the reserved power for the current operating cycle based on the reserved power and the power fluctuation coefficient of the previous operating cycle; determining the upper limit of the charging power based on the actual power generation and the reserved power for the current operating cycle; limiting the target charging power of the power supply circuit according to the upper limit of the charging power; and obtaining electrical energy from the DC bus to charge the battery pack according to the target charging power after the limiting process.

[0006] In one embodiment, the method further includes: acquiring multiple actual power generation values ​​of the DC power generation device collected within a preset time period; calculating the average value and average variance of the multiple actual power generation values ​​collected within the preset time period; and determining the power fluctuation coefficient based on the average variance and the average value.

[0007] In one embodiment, determining the power fluctuation coefficient based on the mean variance and the mean value includes: calculating the ratio of the mean variance to the square of the mean value as the power fluctuation coefficient.

[0008] In one embodiment, determining the reserved power for the current operating cycle based on the reserved power and power fluctuation coefficient of the previous operating cycle includes: determining an adjustment coefficient based on the power fluctuation coefficient and a reference value of the power fluctuation coefficient, wherein the power fluctuation coefficient and the adjustment coefficient are positively correlated; determining a power adjustment step size based on the adjustment coefficient and a reference step size, wherein the power adjustment step size and the power adjustment coefficient are positively correlated; and determining the reserved power for the current operating cycle based on the reserved power and the power adjustment step size of the previous operating cycle.

[0009] In one embodiment, the upper limit of charging power is determined based on the actual power generation and the reserved power of the current operating cycle, including calculating the difference between the actual power generation and the reserved power of the current operating cycle as the upper limit of charging power.

[0010] In one embodiment, limiting the target charging power of the power supply circuit according to the upper limit of charging power includes: obtaining the target charging power of the power supply circuit; when the target charging power is greater than the upper limit of charging power, adjusting the target charging power to the upper limit of charging power; when the target charging power is not greater than the upper limit of charging power, not adjusting the target charging power.

[0011] In one embodiment, the AC output terminal of the inverter is connected to the power grid via an AC bus. The method further includes: obtaining the actual grid-connected power between the AC bus and the power grid; and determining the target charging power of the power supply circuit based on the actual grid-connected power and the target grid-connected power.

[0012] In one embodiment, the method further includes: periodically acquiring the sampled output power of the DC power generation device; and filtering the sampled output power to obtain the actual power generation.

[0013] A second aspect of this application provides a power supply device, which includes a power supply circuit and a controller. The power supply device is installed in a power supply system. The power supply system includes a battery pack, a DC power generation device, an inverter, and the power supply circuit. A first terminal of the power supply circuit is connected to the battery pack, and a second terminal of the power supply circuit, the output terminal of the DC power generation device, and the DC input terminal of the inverter are all connected to a DC bus. The controller is used to execute the charging control method of the power supply circuit as described in any of the preceding claims.

[0014] A third aspect of this application provides an energy storage device, which includes a power supply circuit, a battery pack, and a controller. The energy storage device is installed in a power supply system. The power supply system includes the energy storage device, a DC power generation device, and an inverter. A first terminal of the power supply circuit is connected to the battery pack, and a second terminal of the power supply circuit, the output terminal of the DC power generation device, and the DC input terminal of the inverter are all connected to a DC bus. The controller is used to execute the charging control method of the power supply circuit as described in any of the preceding claims.

[0015] In summary, the charging control method for the power supply circuit provided in this application first obtains the reserved power of the inverter in the previous operating cycle, the actual power generation of the DC power generation equipment, and the power fluctuation coefficient in each operating cycle. Then, the reserved power for the current operating cycle is determined based on the reserved power and power fluctuation coefficient of the previous operating cycle. Since the size of the reserved power affects the fluctuation level of the actual power generation, and the power fluctuation coefficient is used to characterize the fluctuation level of the actual power generation, the size of the reserved power affects the size of the power fluctuation coefficient. Thus, the reserved power of the current operating cycle can be obtained by adjusting the reserved power of the previous operating cycle based on the power fluctuation coefficient. This ensures that the reserved power of the current operating cycle maintains the MPPT function of the inverter while reducing wasted power; furthermore, updating the reserved power in each operating cycle allows it to adapt to different inverters and different operating conditions. Then, the upper limit of the charging power is determined based on the actual power generation and the reserved power. Finally, the target charging power of the power supply circuit is limited according to the upper limit of the charging power to obtain electrical energy from the DC bus to charge the battery pack according to the target charging power. In this way, while ensuring that the inverter has sufficient reserved power to improve the stability of the power supply system, the self-generation and self-consumption of the power supply system can be achieved. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be considered as a limitation on the scope of protection of this application. In the various drawings, similar components are numbered similarly.

[0017] Figure 1 This is a structural block diagram of a power supply system provided in an embodiment of this application.

[0018] Figure 2 This is a flowchart of a charging control method for a power supply circuit provided in an embodiment of this application.

[0019] Figure 3 A flowchart illustrating the process of obtaining actual power generation in a charging control method for a power supply circuit provided in an embodiment of this application.

[0020] Figure 4This is a flowchart of a sub-step of step S202 in one embodiment of this application.

[0021] Figure 5 This is a flowchart of a sub-step of step S204 in one embodiment of this application.

[0022] Figure 6 This is a flowchart illustrating the process of determining the target charging power in a charging control method for a power supply circuit according to an embodiment of this application.

[0023] Figure 7 This is a flowchart illustrating the process of obtaining actual power generation in the charging control method of the power supply circuit in one embodiment of this application.

[0024] Figure 8 This is a control block diagram of a charging control method for a power supply circuit in one embodiment of this application.

[0025] Figure 9 This is a functional block diagram of a power supply device provided in an embodiment of this application.

[0026] Figure 10 A functional block diagram of an energy storage device provided in an embodiment of this application.

[0027] Figure 11 This is a functional block diagram of a control device provided in an embodiment of this application. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0029] It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or may also have an intervening component. When a component is considered to be "placed" on another component, it can be directly placed on the other component or may also have an intervening component. The terms "top," "bottom," "upper," "lower," "left," "right," "front," "back," and similar expressions used in this article are for illustrative purposes only.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0031] Some embodiments will now be described with reference to the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0032] Photovoltaic power generation technology is a technology that converts solar energy into electrical energy to power loads. In related technologies, in order to make full use of solar energy resources, photovoltaic systems use inverters, such as photovoltaic inverters or energy storage converters, to convert the direct current generated by photovoltaic modules into alternating current for the load. At the same time, photovoltaic systems also use energy storage devices to store excess energy supplied by photovoltaic modules to the load, so that when solar energy resources are insufficient, the energy storage devices can be controlled to provide energy to the load through the inverter.

[0033] For example, please see Figure 1 , Figure 1 This is a schematic diagram of a power supply system 10 according to an embodiment of this application. The power supply system 10 includes a battery pack 110, a power supply circuit 120, a DC power generation device 130, and an inverter 140. The first terminal of the power supply circuit 120 is connected to the battery pack 110. The second terminal of the power supply circuit 120, the output terminal of the DC power generation device 130, and the DC input terminal of the inverter 140 are all connected to a DC bus (including a positive DC bus DC_BUS+ and a negative DC bus DC_BUS-). The output terminal of the inverter 140 is connected to the power grid 20 via an AC bus (including a neutral wire N and a live wire L). A load 30 is also connected to the AC bus.

[0034] Furthermore, the battery pack 110 contains one or more cells connected in series and / or parallel. The battery pack 110 is used to store or release energy.

[0035] The power supply circuit 120 includes a DC-DC converter unit. The DC-DC converter unit is used to step up or down the battery voltage of the battery pack 110 before discharging it through the DC bus, or to step up or down the charging voltage provided by the DC bus before charging the battery pack 110. Specifically, when charging, the power supply circuit 120 draws power from the DC generator 130 via the DC bus for power conversion to charge the battery pack 110; when discharging, the power supply circuit 120 draws electrical energy from the battery pack 110 and outputs it to the DC bus.

[0036] Understandably, the DC / DC conversion unit can consist of a BUCK circuit, a BOOST circuit, or a BUCK-BOOST circuit. Thus, by controlling the switching logic and duty cycle of the BUCK circuit, BOOST circuit, or BUCK-BOOST circuit, the DC / DC conversion unit can be controlled to operate in charging or discharging mode, and its output power can be controlled. In other embodiments, the DC / DC conversion unit may include a DAB (Dual Active Bridge) circuit, or a boost circuit and an LLC series-parallel resonant circuit. The specific circuit structures of the boost circuit, DAB circuit, and LLC circuit are not limited here.

[0037] The DC power generation device 130 includes a plurality of photovoltaic panels. The photovoltaic panels convert light energy into electrical energy to output DC power to the inverter 140 and / or charge the battery pack 110 via the power supply circuit 120. Understandably, this application does not limit the connection method of the photovoltaic panels in the DC power generation device 130. For example, in some embodiments, the photovoltaic panels in the DC power generation device 130 may be connected in series, in parallel, or in a series-then-parallel connection, etc.

[0038] Inverter 140 includes at least a Direct Current to Alternating Current (DC / AC) conversion unit to convert the DC power from the DC power generation device 130 and / or power supply circuit 120 obtained from the DC input terminal on the direct bus into AC power, and output it to the AC bus to power the load 30 and / or feed power to the grid 20. Understandably, this application does not limit the specific circuit structure of the DC / AC conversion unit; for example, the DC / AC conversion unit can be a full-bridge topology, a half-bridge topology, etc. In some embodiments, due to the power generation characteristics of the DC power generation device 130 as a photovoltaic power generation device, inverter 140 may also include a Maximum Power Point Tracking (MPPT) circuit to achieve maximum power point tracking of the photovoltaic power generation device.

[0039] The power grid 20 can be, for example, a municipal power grid. Understandably, this application does not limit the type of AC power in the power grid 20; in other embodiments, the power grid 20 can be single-phase AC, three-phase AC, or other multi-phase AC, etc. The load 30 can be various electrical loads in a household, or it can be an important load.

[0040] In this photovoltaic system, when the energy storage device (e.g., battery pack 110) is charged to store the energy generated by the photovoltaic modules (i.e., DC power generation device 130), a certain amount of reserved power is required to maintain the basic operation of the inverter, such as achieving maximum power point tracking (MPPT). However, the reserved power may differ for different inverters. Even for the same inverter, the reserved power will vary under different voltage and current conditions. Related technologies typically employ a single reserved power. This leads to power waste when the reserved power is too high, and instability in certain inverters or under certain operating conditions when the reserved power is too low, thus exacerbating voltage fluctuations in the photovoltaic modules.

[0041] Therefore, this application provides a charging control method for a power supply circuit, which can update the reserved power in real time according to the fluctuation of the actual power generation of the DC power generation equipment, so that the reserved power can be adapted to different inverters and different operating conditions. Understandably, the charging control method for the power supply circuit provided in this application can be applied to... Figure 1 The power supply system 10 is shown. The charging control method of this power supply circuit can be executed by the controller of the power supply circuit 120. Please refer to... Figure 2 The control method includes the following steps: Step S201: In each operating cycle, obtain the reserved power of the inverter in the previous operating cycle, the actual power generation of the DC power generation equipment, and the power fluctuation coefficient; the power fluctuation coefficient is used to characterize the degree of fluctuation of the actual power generation.

[0042] The operating cycle can be set according to actual needs. For example, the operating cycle can be the operating cycle of the controller of the power supply circuit 120.

[0043] The reserved power is used to ensure the basic operation of inverter 140, such as maintaining the MPPT function of DC power generation equipment 130. The reserved power is greater than or equal to the minimum power consumption of inverter 140 to maintain normal operation. In the first operating cycle, an initial value of the reserved power can be obtained as the reserved power for the previous operating cycle. The initial value of the reserved power can be based on data obtained from multiple inverter tests in a laboratory; for example, the initial value of the reserved power can be 600W. In other embodiments, the initial value of the reserved power can be the preset reserved power for different inverters.

[0044] The actual generated power is used to represent the power output from the DC power generation device 130 to the DC bus. The actual generated power is used to charge the battery pack 110 via the power supply circuit 120 and / or to supply power to the load 30 via the inverter 140. Furthermore, the inverter 140 needs to draw at least a reserved power from the DC bus to maintain MPPT functionality. That is, at least a portion of the actual generated power is reserved power for the inverter 140.

[0045] Understandably, the power fluctuation coefficient can be calculated by processing the actual power generation. Understandably, when the environment in which the DC power generation equipment 130 operates changes, the actual power generation of the DC power generation equipment 130 will also change, and the reserved power required by the inverter 140 may also change. Therefore, the reasonableness of the reserved power can be determined based on the calculated power fluctuation coefficient.

[0046] Step S202: Determine the reserved power for the current operating cycle based on the reserved power and power fluctuation coefficient of the previous operating cycle.

[0047] Since the reserved power is used to maintain the MPPT function of inverter 140, if the reserved power is too low and insufficient to maintain the MPPT function, the voltage of DC power generation equipment 130 will fluctuate uncontrollably due to the operating characteristics of the photovoltaic panels, resulting in drastic fluctuations in actual power generation. Conversely, if the reserved power is too high, although this can reduce the fluctuation of actual power generation, it results in energy waste. Furthermore, since the power fluctuation coefficient is used to characterize the degree of fluctuation in actual power generation, the impact of the reserved power in the previous operating cycle on the actual power generation can be determined by observing the magnitude of the power fluctuation coefficient.

[0048] In other words, the size of the reserved power in each operating cycle will affect the size of the power fluctuation coefficient, and it is necessary to determine an appropriate reserved power to reduce the fluctuation of actual power generation while minimizing wasted energy.

[0049] Thus, in step S202, the reserved power for the current operating cycle can be obtained by adjusting the reserved power of the previous operating cycle based on the power fluctuation coefficient. For example, when the value of the power fluctuation coefficient indicates that the fluctuation of the actual power generation is small, the reserved power of the previous operating cycle is reduced to determine the reserved power of the current operating cycle, thereby reducing energy waste. When the value of the power fluctuation coefficient indicates that the fluctuation of the actual power generation is large, the reserved power of the previous operating cycle is increased to determine the reserved power of the current operating cycle, thereby stabilizing the actual power generation.

[0050] Step S203: Determine the upper limit of charging power based on the actual power generation and the reserved power of the current operating cycle.

[0051] The upper limit of charging power is used to characterize the maximum charging power of the power supply circuit 120.

[0052] Please refer to it again. Figure 1When the power supply circuit 120 is charging, it draws energy from the DC bus to charge the battery pack 110. Simultaneously, based on the above, the inverter 140 also needs to draw at least a reserved power from the DC bus to maintain the MPPT function. At this time, the energy on the DC bus is provided by the DC power generation device 130. Thus, the power supply circuit 120 cannot obtain all the actual generated power and needs to reserve power for the inverter 140. Therefore, in step S203 of this application, the upper limit of the charging power of the power supply circuit 120 is determined based on the actual generated power and the reserved power for the current operating cycle to avoid insufficient reserved power in the inverter 140 due to the power supply circuit 120 drawing too much power from the DC bus.

[0053] Step S204: Limit the target charging power of the power supply circuit according to the upper limit of the charging power.

[0054] The target charging power is used to characterize the ideal charging power of the power supply circuit 120.

[0055] In step S204, the target charging power is limited so that the target charging power after the limit is less than or equal to the upper limit of the charging power.

[0056] Step S205: Obtain electrical energy from the DC bus to charge the battery pack according to the target charging power after the limiting process.

[0057] Understandably, by executing step S205, the inverter 140 can be guaranteed to have sufficient reserved power while ensuring that the power supply circuit 120 is charged normally, thereby reducing the fluctuation of the actual power generation and improving the stability of the power supply system 10.

[0058] Thus, the controller cyclically executes steps S201 to S205 in each operating cycle to update the reserved power in each operating cycle and determine the target charging power of the power supply circuit based on the reserved power. In this way, the reserved power of the inverter 140 and the target charging power of the power supply circuit 120 can be refreshed at regular intervals, and the refresh frequency depends on the operating cycle of the controller.

[0059] In summary, the charging control method for the power supply circuit provided in this application first obtains the reserved power of the inverter in the previous operating cycle, the actual power generation of the DC power generation equipment, and the power fluctuation coefficient in each operating cycle. Then, the reserved power for the current operating cycle is determined based on the reserved power and power fluctuation coefficient of the previous operating cycle. Since the size of the reserved power affects the fluctuation level of the actual power generation, and the power fluctuation coefficient is used to characterize the fluctuation level of the actual power generation, the size of the reserved power affects the size of the power fluctuation coefficient. Thus, the reserved power of the current operating cycle can be obtained by adjusting the reserved power of the previous operating cycle based on the power fluctuation coefficient. This ensures that the reserved power of the current operating cycle maintains the MPPT function of the inverter 140 while reducing wasted power; furthermore, updating the reserved power in each operating cycle allows it to adapt to different inverters 140 and different operating conditions. Then, the upper limit of the charging power is determined based on the actual power generation and the reserved power. Finally, the target charging power of the power supply circuit is limited according to the upper limit of the charging power to obtain electrical energy from the DC bus to charge the battery pack 110 according to the target charging power. In this way, while ensuring that the inverter 140 has sufficient reserved power to maintain normal operation and improve the stability of the power supply system 10, the power supply system 10 can be self-generated and self-used.

[0060] Please see Figure 3 In some embodiments, the control method further includes: Step S301: Obtain multiple actual power outputs of the DC power generation equipment collected within a preset time period.

[0061] In some embodiments, the actual power output of the DC power generation device can be periodically collected. Then, multiple actual power outputs within a preset time period are obtained.

[0062] This application does not limit the specific duration of the preset duration.

[0063] Step S302: Calculate the average value and average variance of multiple actual power generation data collected within a preset time period.

[0064] Understandably, the sum of the actual power generation collected within a preset time period can be obtained, and then the sum can be divided by the number of actual power generation collected within the preset time period to obtain the average value of the multiple actual power generation collected within the preset time period.

[0065] Understandably, the square of the difference between each actual power generation and the average value within a preset time period is calculated, and then the average of the squares of multiple sets of differences is calculated to obtain the average variance.

[0066] In some embodiments, a moving average algorithm is used to calculate the average value and average variance over a preset time period. Understandably, the basic principle of the moving average algorithm is to sequentially acquire N actual power generation values. If fewer than N actual power generation values ​​are acquired, the average value of all current actual power generation values ​​is output; if more than N actual power generation values ​​are acquired, the output is equal to the average value of the next N acquired actual power generation values. The moving average algorithm can effectively eliminate periodic interference and some irregular interference. Correspondingly, the average variance of the acquired N actual power generation values ​​can be calculated using the moving average algorithm.

[0067] This application does not impose any restrictions on the parameters (such as the specific value of N) in the moving average algorithm used.

[0068] Step S303: Determine the power fluctuation coefficient based on the average variance and average value.

[0069] Understandably, the average variance is used to represent the average of the squares of the differences between each actual power generation and the average actual power generation. In other words, the average variance characterizes the degree to which multiple actual power generation values ​​obtained within a preset time period deviate from the average actual power generation. Therefore, in step S303, the power fluctuation coefficient can be determined based on the average variance and the average value.

[0070] In some embodiments, step S303 includes: The ratio of the average variance to the square of the average value is calculated as the power fluctuation coefficient.

[0071] For example, the power fluctuation coefficient can be determined according to the following formulas (1) and (2): in, The average variance; This is the average value of multiple actual power generation values ​​obtained within a preset time period; The actual power generation collected; n represents the nth actual power generation within the preset time period; N represents the total number of actual power generation data collected within the preset time period; Power fluctuation coefficient; It is the square of the average value of multiple actual power generation values ​​obtained within a preset time period.

[0072] In other embodiments, the power fluctuation coefficient can also be the ratio of the square root of the average variance to the average value. This application does not limit the specific calculation process for calculating the power fluctuation coefficient.

[0073] In summary, by executing steps S301 to S303, the power fluctuation coefficient in step S201 can be calculated.

[0074] Please see Figure 4 In some embodiments, step S202 includes the following sub-steps: Step S401: Determine the adjustment coefficient based on the power fluctuation coefficient and the power fluctuation coefficient reference value. The power fluctuation coefficient and the adjustment coefficient are positively correlated.

[0075] The adjustment coefficient is used to characterize the impact of the difference between the power fluctuation coefficient and the reference value of the power fluctuation coefficient on the actual power generation.

[0076] In some embodiments, the difference between the power fluctuation coefficient and the power fluctuation coefficient reference value can be used as the adjustment coefficient.

[0077] Step S402: Determine the power adjustment step size based on the adjustment coefficient and the reference step size. The power adjustment step size and the adjustment coefficient are positively correlated.

[0078] The reference step size can be the base step size for each adjustment of the actual power generation. The power adjustment step size is used to characterize the step size for each adjustment of the actual power generation.

[0079] In some embodiments, the product of the adjustment factor and the reference step size can be used as the power adjustment step size.

[0080] Step S403: Determine the reserved power for the current operating cycle based on the reserved power and power adjustment step size of the previous operating cycle.

[0081] In some embodiments, the value obtained by adding the reserved power of the previous operating cycle to the power adjustment step size can be used as the reserved power of the current operating cycle.

[0082] For example, in some embodiments, the reserved power for the current operating cycle can be determined according to the following formula (4): in, Reserved power for the current operating cycle; Reserved power for the previous operating cycle; Power fluctuation coefficient; This is a reference value for the power fluctuation coefficient; This is for reference step size.

[0083] Understandably, this application does not limit the specific calculation formula for determining the reserved power for the current operating cycle. For example, in other embodiments, the reserved power for the current operating cycle can also be determined based on the following formula 5: Where 'a' is an adjustment parameter determined based on the power loss in the DC bus. In some embodiments, 'a' can be a constant.

[0084] In summary, by executing steps 401 to S403, the reserved power for the current operating cycle can be calculated.

[0085] In some embodiments, step S203 includes: The difference between the actual power generation and the reserved power for the current operating cycle is calculated as the upper limit of the charging power.

[0086] Understandably, since the reserved power can be obtained from the DC bus by the inverter 140, and the actual generated power of the DC power generation equipment 130 is output to the DC bus, the reserved power is provided by the actual generated power. Furthermore, since the inverter 140 needs at least the reserved power to maintain normal MPPT function, the difference between the actual generated power and the reserved power of the current operating cycle can be used as the upper limit of charging power.

[0087] Please see Figure 5 In some embodiments, step S204 includes: Step S501: Obtain the target charging power of the power supply circuit.

[0088] The target charging power is used to characterize the ideal value of the charging power of the power supply circuit 120. In some embodiments, the target charging power can be calculated based on the closed-loop power control algorithm of the power supply system 10.

[0089] Step S502: When the target charging power is greater than the upper limit of the charging power, adjust the target charging power to the upper limit of the charging power.

[0090] Step S503: When the target charging power is not greater than the upper limit of the charging power, the target charging power is not adjusted. Thus, by performing the above steps S501 to S503, the target charging power can be made less than or equal to the upper limit of the charging power, thereby ensuring that the inverter 140 can obtain at least the reserved power.

[0091] Please see Figure 6 In some embodiments, the control method further includes: Step S601: Obtain the actual grid-connected power between the AC bus and the power grid.

[0092] Please refer to it again. Figure 1Understandably, when the output of inverter 140 is connected to the grid 20 via the AC bus, it is called grid-connected. Actual grid-connected power is used to represent the power supply relationship between inverter 140 connected to the AC bus, load 30, and grid 20. For example, depending on the energy flow direction between inverter 140, load 30, and grid 20, the actual grid-connected power can be positive, negative, or zero. For instance, when inverter 140 outputs 10W to grid 20 via the AC bus, the actual grid-connected power is 10W; when grid 20 outputs 10W to the AC bus to supply power to load 30, the actual grid-connected power is -10W; when the output power of inverter 140 exactly meets the power demand of load 30, i.e., when inverter 140 neither outputs power to grid 20 nor grid 20 outputs power to load 30, the actual grid-connected power is zero.

[0093] It is understood that the definitions of positive and negative actual grid-connected power in this application are merely exemplary. In other embodiments, when the actual grid-connected power is positive, it may also indicate that the grid is supplying power to the load, and when the actual grid-connected power is negative, it may indicate that the inverter 140 is selling electricity to the grid 20.

[0094] In some embodiments, a grid monitoring module (not shown in the figure) can be installed between the local microgrid system consisting of the power supply system 10 and the load 30 and the power grid 20, that is, between the common connection point of the inverter 140 output terminal and the load 30 and the power grid 20. The grid monitoring module is used to monitor the grid connection parameters between the AC bus and the power grid 20. The grid connection parameters may include grid connection current, grid connection voltage, and actual grid connection power. In this way, the controller of the power supply circuit 120 can obtain the actual grid connection power output from the inverter 140 to the power grid 20, or from the power grid 20 to the load 30, by communicating with the grid monitoring module. In some embodiments, the grid monitoring module can be a smart meter, such as a bidirectional power sensor, and the smart meter can transmit the actual grid connection power.

[0095] Understandably, the communication between the controller and the power grid monitoring module can be wireless communication (such as Bluetooth communication, ZigBee communication, etc.) or wired communication (such as serial communication methods based on RS-485 serial bus, or Controller Area Network (CAN) bus, or other parallel communication methods). This application does not limit the specific communication method. In other embodiments, the controller may communicate with the inverter 140 and the load 30 to obtain the actual output power of the inverter 140 and the actual power consumed by the load 30, thereby calculating the actual grid-connected power based on the actual output power and the actual power consumed.

[0096] Step S602: Determine the target charging power of the power supply circuit based on the actual grid-connected power and the target grid-connected power.

[0097] The target grid-connected power is used to characterize the ideal value of the actual grid-connected power between the AC bus and the grid 20. For example, in some embodiments, the target grid-connected power is 0, in which case the power output of the inverter 140 just meets the power demand of the load 30. Thus, the inverter 140 does not need to buy electricity from the grid 20, nor does it need to sell electricity to the grid 20. In some embodiments, the target grid-connected power can also be a negative or positive number. The meaning of a negative or positive target grid-connected power is roughly the same as the meaning of a positive or negative actual grid-connected power, and will not be repeated here. Understandably, this application does not limit the specific value of the target grid-connected power.

[0098] Understandably, when the actual grid-connected power is greater than the target grid-connected power, it means that the power output of the inverter 140 to the grid 20 is greater than expected. In this case, the battery pack 110 can be charged to store some of the energy output by the DC power generation equipment 130. When the actual grid-connected power is less than the target grid-connected power, it means that the power output of the inverter 140 is insufficient to meet the needs of the load 30. The load 30 draws power from the grid. In this case, the power supply circuit 120 can obtain electrical energy from the battery pack 110 and discharge it to the DC bus to increase the actual output power of the inverter 140 and reduce the power draw from the grid 20.

[0099] Thus, when the actual grid-connected power is greater than the target grid-connected power, the difference between the actual grid-connected power and the target grid-connected power can be used as the target charging power, so as to control the power supply circuit 120 to charge the battery pack 110 according to the target charging power.

[0100] This application does not limit the specific calculation method for the target discharge power, as long as it satisfies the inventive concept of determining the target discharge power based on the difference between the actual grid-connected power and the target grid-connected power. For example, in some other embodiments, factors such as power loss in the power supply system or errors in the smart grid monitoring module can be further combined to determine the target discharge power based on the difference between the actual grid-connected power and the target grid-connected power.

[0101] Please see Figure 7 In some embodiments, the control method further includes: Step S701: Periodically collect the sampled output power of the DC power generation equipment.

[0102] In some embodiments, the sampled output power of the DC power generator 130 can be acquired in real time by setting a sensor (e.g., a Hall sensor or other power measurement sensor) at the output terminal of the DC power generator 130 and communicating with the sensor. In other embodiments, a current sensor and a voltage sensor can also be set at the output terminal of the DC power generator 130 and communicate with the sensor. In this way, the controller can calculate the sampled output power of the DC power generator 130 based on the acquired actual output current and actual output voltage.

[0103] Understandably, the sampling period in step S701 may be out of sync with the running period in step S201, and this application does not impose any restrictions on the sampling period in step S701.

[0104] Step S702: Filter the sampled output power to obtain the actual generated power.

[0105] Understandably, when the DC power generation equipment 130 is affected by the environment, the actual power generation of the DC power generation equipment 130 is prone to fluctuation. For example, when the weather changes in the environment where the photovoltaic modules in the DC power generation equipment 130 are located, or when the photovoltaic modules are blocked by obstructions (such as clouds, leaves, etc.), the actual power generation of the photovoltaic modules is prone to fluctuation. Therefore, in step S702, the actual power generation is filtered to obtain a power filter value in order to eliminate the fluctuation in the actual power generation as much as possible.

[0106] The filtering process in step S702 can be based on low-pass filtering, average filtering, median filtering, etc. This application does not limit the filtering algorithm used in step S702.

[0107] In summary, by executing steps S701 to S702, the actual power generation obtained can be more accurate, and the interference of the environment where the DC power generation equipment 130 is located on this solution can be reduced.

[0108] Please continue reading. Figure 8 , Figure 8 This diagram illustrates a specific control block diagram and power flow diagram of a charging control method for a power supply circuit provided in an embodiment of this application, implemented using a closed-loop control algorithm. The following is based on... Figure 8 The specific workflow of the charging control method for the power supply circuit is explained below: First, the actual grid-connected power P_real between the AC bus and the power grid 20 is obtained through the smart meter 40. Then, the deviation power P_dev between the actual grid-connected power P_real and the target grid-connected power P_aim is calculated through the first adder 151. Finally, the target charging power P_dsg of the power supply circuit 120 is determined based on the deviation power P_dev and the deviation adjustment algorithm preset in the PI controller 152.

[0109] Then, the reserved power P_res for the current operating cycle and the actual power generation P_pv of the DC power generation device 130 are obtained, so as to determine the upper limit of charging power P_max through the second adder 153. Among them, the reserved power P_res for the current operating cycle is calculated based on the algorithm provided in the embodiments of this application, according to the actual power generation P_pv of the DC power generation device, the power fluctuation coefficient and the reserved power of the previous operating cycle.

[0110] Next, the limiter 154 limits the target charging power P_dsg according to the upper limit of the charging power P_max to obtain the target charging power P_dsg_tag after the limit processing.

[0111] Furthermore, the power supply circuit 120 draws power from the DC bus according to the target charging power P_dsg_tag after the limiting process. The remaining photovoltaic power P_pv is input to the DC input terminal of the inverter 140. The DC power P_dc received at the DC input terminal of the inverter 140 can be obtained by subtracting the target charging power P_dsg_tag after the limiting process from the photovoltaic power P_pv using the third adder 155. The inverter 140 performs power conversion on the DC power P_dc received at the DC input terminal to output AC power P_ac to the AC bus, so as to provide at least part of the demand power P_need for the load 30. Further, the unmet power of the load 30, or the power flowing to the grid 20 after the AC power P_ac meets the load's demand power P_need, can be calculated by the fourth adder 156.

[0112] Understandably, the PI controller 152 described above uses an existing controller in the related art, such as a PI controller (proportional-integral controller), as an example. In other embodiments, other controllers, such as a PID controller (proportional-integral-derivative controller), etc., may also be used, and this application does not limit this. Correspondingly, the deviation adjustment algorithm may also be a PI adjustment algorithm (proportional-integral control), a PID adjustment algorithm (proportional-integral-derivative control), etc., or of course, other adjustment algorithms.

[0113] In this way, the reserved power can be updated in each operating cycle, thereby ensuring the normal operation of the inverter while charging the battery pack.

[0114] Please see Figure 9 This application also provides a power supply device 100, including a power supply circuit 120 and a controller 150. The power supply device 100 is disposed in a power supply system 10. The power supply system 10 includes a battery pack 110, a DC power generator 130, an inverter 140, and the power supply device 100. A first terminal of the power supply circuit 120 is connected to the battery pack 110, and a second terminal of the power supply circuit 120, the output terminal of the DC power generator 130, and the DC input terminal of the inverter 140 are all connected to a DC bus. When discharging, the power supply circuit 120 obtains electrical energy from the battery pack 110 and outputs it to the DC bus. The controller 150 is used to execute the discharge control method of the power supply circuit as described in any of the above embodiments.

[0115] In some embodiments, the DC bus is configured within the power supply device 100. In other embodiments, the DC bus may also be configured by other electronic devices connected to the power supply device 100, such as by the inverter 140.

[0116] Please see Figure 10This application also provides an energy storage device 200. The energy storage device 200 includes a power supply circuit 120, a battery pack 110, and a controller 150. The energy storage device 200 is disposed in a power supply system 10. The power supply system 10 includes a DC power generation device 130, an inverter 140, and the energy storage device 200. A first terminal of the power supply circuit 120 is connected to the battery pack 110, and a second terminal of the power supply circuit 120, the output terminal of the DC power generation device 130, and the DC input terminal of the inverter 140 are all connected to a DC bus. When the power supply circuit 120 discharges, it obtains electrical energy from the battery pack 110 and outputs it to the DC bus. The controller 150 is used to execute the discharge control method of the power supply circuit as described in any of the above embodiments.

[0117] Understandably, in some embodiments, the DC bus may also be located in the energy storage device 200. In other embodiments, the DC bus may also be configured by other electronic devices connected to the energy storage device 200, such as the inverter 140.

[0118] Understandably, the energy storage device 200 can be various electronic devices equipped with a battery pack 110, such as mobile energy storage devices, home energy storage devices, portable air conditioners, portable refrigerators, etc. This application does not limit the specific functions of the energy storage device 200.

[0119] Understandably, the controller 150 is equipped with an Energy Management System (EMS), which executes the discharge control method of the power supply circuit provided in this application, thereby achieving unified control of the energy storage device 200. The controller 150 can be a processor independent of the battery pack 110 and the power supply circuit 120, or it can be a processor simultaneously equipped with a Battery Management System (BMS) for controlling the battery pack 110. This application does not limit the specific form of the controller.

[0120] In some embodiments, the controller 150 can communicate with the battery pack 110 via a CAN bus, and with the power supply circuit 120 and the electricity meter via an RS-485 serial bus. In other embodiments, the controller 150 can also communicate with the battery pack 110 and the power supply circuit 120 via other wired or wireless communication methods, and this application does not limit this.

[0121] One embodiment of this application also provides a control device applied to a power supply circuit 120 or an electronic device integrating a power supply circuit 120. Figure 11 A schematic block diagram of the control device 300 provided in an embodiment of this application is shown. Figure 11 As shown, the control device 300 includes: The acquisition module 310 is used to acquire, in each operating cycle, the reserved power of the inverter in the previous operating cycle, the actual power generation of the DC power generation equipment, and the power fluctuation coefficient; the power fluctuation coefficient is used to characterize the degree of fluctuation of the actual power generation.

[0122] The first determining module 320 is used to determine the reserved power for the current operating cycle based on the reserved power and power fluctuation coefficient of the previous operating cycle.

[0123] The second determining module 330 is used to determine the upper limit of charging power based on the actual power generation and the reserved power of the current operating cycle.

[0124] Limiting module 330 is used to limit the target charging power of the power supply circuit according to the upper limit of the charging power.

[0125] The control module 340 is used to obtain electrical energy from the DC bus to charge the battery pack according to the target charging power after the limiting process.

[0126] The specific details of the discharge control method for the power supply circuit implemented by the control device 300 in this application embodiment have been described in detail in the corresponding embodiment of the discharge control method for the power supply circuit, and will not be repeated here.

[0127] This application also provides a computer-readable medium storing a computer program thereon, which, when executed by a processor, implements the discharge control method for the power supply circuit as described in the above technical solutions. The computer-readable medium may be a portable compact disc read-only memory (CD-ROM) and include program code, and can run on a terminal device, such as a personal computer. However, the program product of this invention is not limited thereto. In this document, the readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0128] The above-described program product may employ any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of readable storage media (a non-exhaustive list) include: electrical connections having one or more wires, portable disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0129] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A readable signal medium may also be any readable medium other than a readable storage medium, capable of sending, propagating, or transmitting programs for use by or in conjunction with an instruction execution system, apparatus, or device.

[0130] The program code contained on the readable medium may be transmitted using any suitable medium, including but not limited to wireless, wired, optical fiber, RF, etc., or any suitable combination thereof.

[0131] Program code for performing the operations of this invention can be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java and C++, and conventional procedural programming languages ​​such as C or similar languages. The program code can execute entirely on the user's computing device, partially on the user's device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server. In cases involving remote computing devices, the remote computing device can be connected to the user's computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0132] Furthermore, the above figures are merely illustrative of the processes included in the method according to exemplary embodiments of the present invention, and are not intended to be limiting. It is readily understood that the processes shown in the above figures do not indicate or limit the temporal order of these processes. Additionally, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0133] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A charging control method for a power supply circuit, wherein the power supply circuit is disposed in a power supply system, characterized in that, The power supply system includes a battery pack, a DC power generation device, an inverter, and the power supply circuit. A first terminal of the power supply circuit is connected to the battery pack, and a second terminal of the power supply circuit, the output terminal of the DC power generation device, and the DC input terminal of the inverter are all connected to a DC bus. The method includes: In each operating cycle, the reserved power of the inverter in the previous operating cycle, the actual power generation of the DC power generation equipment, and the power fluctuation coefficient are obtained; the power fluctuation coefficient is used to characterize the degree of fluctuation of the actual power generation, and the reserved power is used to maintain the consumption when the inverter is operating the maximum power point tracking function; The reserved power for the current operating cycle is determined based on the power fluctuation coefficient reference value, the reserved power of the previous operating cycle, and the power fluctuation coefficient. Specifically, when the power fluctuation coefficient is less than the power fluctuation coefficient reference value, the reserved power of the previous operating cycle is reduced to determine the reserved power for the current operating cycle. When the power fluctuation coefficient is greater than the power fluctuation coefficient reference value, the reserved power of the previous operating cycle is increased to determine the reserved power for the current operating cycle. The upper limit of charging power is determined based on the actual power generation and the reserved power for the current operating cycle; The target charging power of the power supply circuit is limited according to the upper limit of the charging power. The target charging power, after being limited, is used to obtain electrical energy from the DC bus to charge the battery pack.

2. The method according to claim 1, characterized in that, The method further includes: Acquire multiple actual power outputs of the DC power generation equipment collected within a preset time period; Calculate the average value and average variance of the multiple actual power generation data collected within the preset time period; The power fluctuation coefficient is determined based on the mean variance and the mean value.

3. The method according to claim 2, characterized in that, The step of determining the power fluctuation coefficient based on the average variance and the average value includes: The ratio of the average variance to the square of the average value is calculated as the power fluctuation coefficient.

4. The method according to claim 1, characterized in that, The step of determining the reserved power for the current operating cycle based on the power fluctuation coefficient reference value, the reserved power of the previous operating cycle, and the power fluctuation coefficient includes: An adjustment coefficient is determined based on the power fluctuation coefficient and the power fluctuation coefficient reference value, wherein the power fluctuation coefficient and the adjustment coefficient are positively correlated. The power adjustment step size is determined based on the adjustment coefficient and the reference step size, and the power adjustment step size is positively correlated with the adjustment coefficient. The reserved power for the current operating cycle is determined based on the reserved power of the previous operating cycle and the power adjustment step size.

5. The method according to claim 1, characterized in that, The step of determining the upper limit of charging power based on the actual power generation and the reserved power of the current operating cycle includes... The difference between the actual power generation and the reserved power for the current operating cycle is calculated as the upper limit of the charging power.

6. The method according to claim 1, characterized in that, The step of limiting the target charging power of the power supply circuit according to the upper limit of the charging power includes: Obtain the target charging power of the power supply circuit; When the target charging power is greater than the upper limit of the charging power, the target charging power is adjusted to the upper limit of the charging power. When the target charging power is not greater than the upper limit of the charging power, the target charging power is not adjusted.

7. The method according to claim 1, characterized in that, The inverter's AC output terminal is connected to the power grid via an AC bus, and the method further includes: Obtain the actual grid-connected power between the AC bus and the power grid; The target charging power of the power supply circuit is determined based on the actual grid-connected power and the target grid-connected power.

8. The method according to claim 1, characterized in that, The method further includes: The sampling output power of the DC power generation equipment is periodically collected; The actual power generation is obtained by filtering the sampled output power.

9. A power supply device, characterized in that, The power supply device includes a power supply circuit and a controller. The power supply device is installed in a power supply system. The power supply system includes a battery pack, a DC power generation device, an inverter, and the power supply circuit. The first end of the power supply circuit is used to connect to the battery pack. The second end of the power supply circuit, the output end of the DC power generation device, and the DC input end of the inverter are all connected to the DC bus. The controller is used to execute the charging control method of the power supply circuit as described in any one of claims 1-8.

10. An energy storage device, characterized in that, The energy storage device includes a power supply circuit, a battery pack, and a controller. The energy storage device is installed in a power supply system, which includes the energy storage device, a DC power generation device, and an inverter. The first end of the power supply circuit is used to connect to the battery pack, and the second end of the power supply circuit, the output end of the DC power generation device, and the DC input end of the inverter are all connected to a DC bus. The controller is used to execute the charging control method of the power supply circuit as described in any one of claims 1-8.

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