Duty Cycle Adjustment Method and Charging Device

Abstract

The present application discloses a duty cycle adjustment method and a charging device. The duty cycle adjustment method includes: when determining that the charging device is loaded, adjusting a first duty cycle to gradually increase according to a target duty cycle and the output voltage of a power supply until the first duty cycle is greater than or equal to the target duty cycle and / or the output voltage of the power supply is less than or equal to the minimum output voltage of the power supply; adjusting the first duty cycle according to the output power of the power supply and the direction of the disturbance when the first duty cycle is disturbed; generating a maximum output current according to the output voltage of the charging device and its maximum output voltage; generating a second duty cycle according to the maximum output current and the first output current of the charging device; determining a third duty cycle according to the minimum value of the adjusted first duty cycle and the second duty cycle, and setting the first duty cycle to the third duty cycle. Through the above method, the stability and reliability of the operation of the photovoltaic module can be improved, and the maximum power of the photovoltaic module can be tracked more reliably.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of duty cycle adjustment, and in particular to a duty cycle adjustment method and a charging device. Background Art

[0002] When the PV panel output voltage matches the operating voltage range of the energy storage device, the energy storage device can be directly connected to the PV panel. However, when the PV panel output voltage exceeds the voltage range required for safe or effective operation of the energy storage device, a charging device is required to regulate the PV panel output voltage. This charging device typically has a step-down function, adjusting the voltage generated by the PV panel to a level suitable for the energy storage device. Summary of the Invention

[0003] The embodiments of the present application provide a duty cycle adjustment method and a charging device, which can improve the stability and reliability of the operation of a photovoltaic module and can more reliably track the maximum power of the photovoltaic module.

[0004] In a first aspect, an embodiment of the present application provides a duty cycle adjustment method for adjusting a first duty cycle of a first pulse width modulation signal applied to a charging device, the charging device being connected to a power supply, the method comprising: when determining that the charging device is loaded, performing the following steps: adjusting the first duty cycle to gradually increase according to a target duty cycle and the output voltage of the power supply until the first duty cycle is greater than or equal to the target duty cycle and / or the output voltage of the power supply is less than or equal to the minimum output voltage of the power supply; adjusting the first duty cycle according to the output power of the power supply and the disturbance direction when the first duty cycle is disturbed, wherein when the average value of the output power in the current adjustment cycle decreases relative to the average value of the output power in the previous adjustment cycle, the disturbance direction is the first direction, and the duration of the adjustment cycle is the duration of adjusting the first duty cycle once; generating a maximum output current of the charging device according to the output voltage of the charging device and the maximum output voltage of the charging device; generating a second duty cycle according to the maximum output current and the first output current of the charging device; determining a third duty cycle according to the minimum value of the adjusted first duty cycle and the second duty cycle, and setting the first duty cycle to the third duty cycle.

[0005] In one or more embodiments, the step of adjusting the first duty cycle to gradually increase according to the target duty cycle and the output voltage of the power supply includes: in each adjustment cycle, when the first duty cycle is less than the target duty cycle and the output voltage of the power supply is greater than the minimum output voltage, adjusting the first duty cycle to the sum of the first duty cycle and a first preset increase value, so as to adjust the first duty cycle to gradually increase.

[0006] In one or more embodiments, after executing the step of adjusting the first duty cycle to the sum of the first duty cycle and the first preset increase value, the method also includes: when the average value of the output power of the current adjustment period is greater than the recorded maximum power, the average value of the output power of the current adjustment period is recorded as the maximum power, and the adjusted first duty cycle is recorded as the first duty cycle corresponding to the maximum power.

[0007] In one or more embodiments, before executing the step of adjusting the first duty cycle to gradually increase according to the target duty cycle and the output voltage of the power supply until the first duty cycle is greater than or equal to the target duty cycle and / or the output voltage of the power supply is less than or equal to the minimum output voltage of the power supply, the method further includes: determining whether the preliminary adjustment process of the first duty cycle has been completed; if not, executing the step of adjusting the first duty cycle to gradually increase according to the target duty cycle and the output voltage of the power supply until the first duty cycle is greater than or equal to the target duty cycle and / or the output voltage of the power supply is less than or equal to the minimum output voltage of the power supply; if so, executing the step of adjusting the first duty cycle according to the output power of the power supply and the disturbance direction when the first duty cycle is disturbed; after executing the step of adjusting the first duty cycle to gradually increase according to the target duty cycle and the output voltage of the power supply until the first duty cycle is greater than or equal to the target duty cycle and / or the output voltage of the power supply is less than or equal to the minimum output voltage of the power supply, the method further includes: determining that the preliminary adjustment process of the first duty cycle has been completed; and recording the adjusted first duty cycle as the first duty cycle corresponding to the maximum power.

[0008] In one or more embodiments, the method further includes: determining a preset target value based on 1 / K, a ratio of an output voltage of the charging device to an input voltage of the charging device, where K is greater than 0 and less than 1.

[0009] In one or more embodiments, the step of adjusting the first duty cycle according to the output power of the power supply and the disturbance direction when the first duty cycle is disturbed includes: when it is determined that the disturbance direction of the current adjustment cycle is the first direction, recording the average value of the output power of the current adjustment cycle as the maximum power, adjusting the direction of the disturbance amount of the first duty cycle to the reverse direction, and adjusting the disturbance direction not to the first direction.

[0010] In one or more embodiments, the step of adjusting the first duty cycle according to the output power of the power supply and the disturbance direction when the first duty cycle is disturbed includes: when it is determined that the disturbance direction of the current adjustment period is not the first direction, performing the following steps: if the average value of the output power of the current adjustment period is less than the recorded maximum power, or the current value of the output voltage of the charging device is less than the minimum output voltage, adjusting the disturbance direction to the first direction; if the average value of the output power of the current adjustment period is greater than or equal to the recorded maximum power, and the current value of the output voltage of the charging device is greater than or equal to the minimum output voltage, recording the average value of the output power of the current adjustment period as the maximum power, and adjusting the duty cycle to the sum of the current value and the disturbance amount.

[0011] In one or more embodiments, after executing the step of adjusting the first duty cycle according to the output power of the power supply and the disturbance direction when disturbing the first duty cycle, the method further includes: when the first duty cycle is greater than the maximum duty cycle, adjusting the disturbance direction to the first direction and setting the first duty cycle to the maximum duty cycle.

[0012] In one or more embodiments, after executing the step of adjusting the first duty cycle according to the output power of the power supply and the disturbance direction when the first duty cycle is disturbed, the method further includes: when the first duty cycle is less than the maximum duty cycle and the first duty cycle is less than the minimum duty cycle, adjusting the disturbance direction to the first direction and setting the first duty cycle to the minimum duty cycle.

[0013] In one or more embodiments, a maximum output current of the charging device is generated based on the output voltage of the charging device and the maximum output voltage of the charging device, including: performing PI adjustment on the difference between the output voltage of the charging device and the maximum output voltage to generate the maximum output current; and a first duty cycle is generated based on the maximum output current and the first output current of the charging device, including: performing PI adjustment on the difference between the maximum output current and the first output current to generate a second duty cycle.

[0014] In a second aspect, an embodiment of the present application provides a charging device, comprising: a charging circuit connected to a power supply and configured to output a bus voltage based on the voltage output by the power supply; a first control unit connected to the charging circuit, for adjusting the duty cycle of a first pulse width modulation signal applied to the charging device, comprising: at least one processor and a memory; the memory is coupled to the processor, the memory being used to store instructions or programs, and when the instructions or programs are executed by at least one processor, the at least one processor executes the duty cycle adjustment method as described above.

[0015] The present application has the following beneficial effects: The duty cycle adjustment method of the embodiment of the present application is used to adjust the first duty cycle of a first pulse width modulation signal applied to a charging device, wherein the charging device is connected to a power source. When the power source is a photovoltaic module and the charging device is determined to be loaded, the method first gradually increases the first duty cycle based on a preset target duty cycle and the output voltage of the power source. Initially, the first duty cycle is increased at a slower rate to prevent the abnormal situation of the photovoltaic module's output voltage continuously decreasing, thereby improving the stability of the photovoltaic module's operation and ensuring stable power supply. Subsequently, the method adjusts the first duty cycle based on the output power of the power source and the direction of the disturbance of the first duty cycle. In this case, when the photovoltaic module is providing stable power, the maximum power of the photovoltaic module can be reliably tracked based on the output power and the disturbance direction. Simultaneously, the maximum output current of the charging device is generated based on the output voltage of the charging device and the maximum output voltage of the charging device, and a second duty cycle is generated based on the maximum output current and the first output current of the charging device, thereby achieving constant voltage and current limiting functions. Finally, the third duty cycle is determined based on the minimum value of the adjusted first duty cycle and the second duty cycle, and the first duty cycle is set to the third duty cycle. This enables the charging device to simultaneously have the functions of constant voltage, current limiting and tracking the maximum power of the photovoltaic module, which is beneficial to improving the stability and reliability of the photovoltaic module. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] One or more embodiments are exemplarily described by the figures in the accompanying drawings, which are not intended to limit the embodiments. Elements with the same reference numerals in the drawings represent similar elements.

[0017] Figure 1 This is a schematic diagram of the charging control system provided by the embodiment of the present application. Figure 1 ;

[0018] Figure 2 This is a schematic diagram of the charging control system provided by the embodiment of the present application. Figure 2 ;

[0019] Figure 3 This is a schematic diagram of the charging control system provided by the embodiment of the present application. Figure 3 ;

[0020] Figure 4 This is the process of the duty cycle adjustment method provided in the embodiment of the present application Figure 1 ;

[0021] Figure 5 This embodiment of the present application provides Figure 4 A schematic diagram of an embodiment of step S420 is shown in FIG.

[0022] Figure 6This is the process of the duty cycle adjustment method provided in the embodiment of the present application Figure 2 ;

[0023] Figure 7 This embodiment of the present application provides Figure 4 A schematic diagram of an embodiment of step S430 is shown in FIG.

[0024] Figure 8 This embodiment of the present application provides Figure 4 A schematic diagram of another embodiment of step S430 is shown in FIG.

[0025] Figure 9 The embodiment of the present application provides that after the execution of Figure 4 Flowchart of steps further performed after step S430 shown in FIG.

[0026] Figure 10 This is an embodiment of the present application Figure 4 A schematic diagram of an embodiment of step S440 and step S450 is shown in FIG.

[0027] Figure 11 The embodiment of this application provides Figure 10 Schematic diagram of the control method corresponding to the steps shown;

[0028] Figure 12 The process of the duty cycle adjustment method of the embodiment of the present application is as follows Figure 3 ;

[0029] Figure 13 This is the process of the duty cycle adjustment method provided in the embodiment of the present application Figure 4 ;

[0030] Figure 14 This embodiment of the present application provides Figure 13 A schematic diagram of an embodiment of step S1310 is shown in FIG.

[0031] Figure 15 This is a step of setting a preset duty cycle provided in an embodiment of the present application;

[0032] Figure 16 This is a method for determining AC components, peak values, and frequencies provided in an embodiment of the present application;

[0033] Figure 17 is a schematic diagram of a control method for an energy storage device provided in an embodiment of the present application;

[0034] Figure 18 This embodiment of the present application provides Figure 13 A schematic diagram of an embodiment of step S1340 is shown in FIG.

[0035] Figure 19This embodiment of the present application provides Figure 18 Schematic diagram of one embodiment of step S1830 shown in FIG. DETAILED DESCRIPTION

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, not all of them. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0037] It should be noted that, when an element is described as being “connected to” another element, it may be directly connected to the other element, or one or more intervening elements may exist therebetween.

[0038] In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as there is no structural conflict between them.

[0039] Please refer to Figure 1 , Figure 1 Schematic diagram of an application scenario provided by an embodiment of the present application. The application scenario is a charging control system 100. The charging control system 100 includes a charging device 10, an energy storage device 20, and a power supply 30.

[0040] Power supply 30 is used to provide a continuous and stable voltage and current. In some embodiments, power supply 30 is a photovoltaic module. A photovoltaic module is a functional unit that can independently output direct current power, formed by connecting multiple individual solar cells in series or parallel, then encapsulating and protecting them. A photovoltaic module is used to directly convert sunlight energy into electrical energy.

[0041] The energy storage device 20 is used to store electrical energy or other forms of energy and release it when needed. The energy storage device 20 receives the bus voltage VBUS and a second pulse width modulation (PWM) signal. The energy storage device 20 is configured to store energy based on the bus voltage VBUS in response to the second PWM signal. In one specific embodiment, the energy storage device 20 steps up or steps down the bus voltage VBUS in response to the second PWM signal, and stores energy based on the stepped-up or stepped-down voltage.

[0042] The charging device 10 is connected to the energy storage device 20 and provides electrical energy to the energy storage device 20. In some embodiments, the charging device 10 receives a first pulse-width modulation signal and, in response to the first pulse-width modulation signal, converts the voltage output by the power source 30 into a bus voltage VBUS. The connection line between the charging device 10 and the energy storage device 20 serves as the bus. In one specific embodiment, the charging device 10 steps down the voltage output by the power source 30 in response to the first pulse-width modulation signal to obtain the bus voltage VBUS.

[0043] In some embodiments, as Figure 2 As shown, the charging device 10 includes a charging circuit 11 and a first control unit 12. The charging circuit 11 is configured to step down the voltage output by the power supply 30 in response to a first pulse-width modulation signal to obtain a bus voltage VBUS. The first control unit 12 is configured to output the first pulse-width modulation signal. The first control unit 12 can be implemented as a microcontroller unit (MCU) or a digital signal processing (DSP) controller.

[0044] The energy storage device 20 includes an energy storage circuit 21 and a second control unit 22. The energy storage circuit 21 is configured to boost or buck the bus voltage VBUS in response to a second pulse-width modulation signal and to store energy based on the boosted or bucked voltage. The second control unit 22 is configured to output the second pulse-width modulation signal. The second control unit 22 can be implemented as a microcontroller unit (MCU) or a digital signal processing (DSP) controller.

[0045] Figure 3 Schematic diagram of a circuit structure of the charging circuit 11 and the first control unit 12. Figure 3 As shown, the charging circuit 11 includes a first NMOS transistor Q1, a first diode D1, a first inductor L1, and a first capacitor C1. The gate of the first NMOS transistor Q1 inputs a first pulse-width modulation signal, the source of the first NMOS transistor Q1 is connected to the cathode of the first diode D1 and the first end of the first inductor L1, respectively, the drain of the first NMOS transistor Q1 is connected to the positive electrode of the power supply 30, the second end of the first inductor L1 is connected to the first end of the first capacitor C1 and the positive electrode of the energy storage device 20, and the anode of the first diode D1 is connected to the negative electrode of the power supply 30, the second end of the first capacitor C1, and the negative electrode of the energy storage device 20.

[0046] Specifically, the first NMOS transistor Q1 is turned on or off in response to the first pulse width modulation signal to step down the output voltage of the power supply 30 and obtain the bus voltage VBUS, which is input to the energy storage device 20 .

[0047] The first control unit 12 includes at least one processor 121 and a memory 122, wherein the memory 122 can be built into the first control unit 12 or externally located outside the first control unit 12. The memory 122 can also be a remotely located memory connected to the first control unit 12 via a network.

[0048] The memory 122 is a non-volatile computer-readable storage medium that can be used to store non-volatile software programs, non-volatile computer executable programs, and modules. The memory 122 may include a program storage area and a data storage area, wherein the program storage area may store an operating system and application programs required for at least one function; the data storage area may store data created based on the use of the terminal, etc. In addition, the memory 122 may include a high-speed random access memory and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some embodiments, the memory 122 may optionally include a memory remotely located relative to the processor 121, and these remote memories may be connected to the terminal via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0049] The processor 121 performs various functions of the terminal and processes data by running or executing software programs and / or modules stored in the memory 122, and calling data stored in the memory 122, thereby monitoring the terminal as a whole, for example, implementing the steps performed by the charging device 10 in the duty cycle adjustment method in any embodiment of the present application.

[0050] The processor 121 may be one or more, Figure 3 In the figure, a processor 121 is used as an example. The processor 121 and the memory 122 may be connected via a bus or other means. The processor 121 may include a central processing unit (CPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a controller, a field-programmable gate array (FPGA) device, etc. The processor 121 may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration.

[0051] Figure 3 The figure also shows an exemplary circuit structure of the energy storage circuit 21 and the second control unit 22. Figure 3As shown, the energy storage circuit 21 includes a second NMOS transistor Q2, a third NMOS transistor Q3, a second diode D2, a third diode D2, a second inductor L2, a first capacitor C1, a second capacitor C2, and a battery B1. One of the gates of the second NMOS transistor Q2 and the third NMOS transistor Q3 receives a second pulse-width modulation signal, while the other receives a low-level signal. The source of the second NMOS transistor Q2 is connected to the cathode of the second diode D2 and the first end of the second inductor L2, respectively. The drain of the second NMOS transistor Q2 is connected to the charging circuit 11. The second end of the second inductor L2 is connected to the drain of the third NMOS transistor Q3 and the anode of the third diode D2, respectively. The cathode of the third diode D2 is connected to the first end of the second capacitor C2 and the positive electrode of the battery B1, respectively. The anode of the second diode D2 is connected to the source of the third switching transistor Q3, the second end of the second capacitor C2, the negative electrode of the battery B1, and the charging device 11, respectively.

[0052] Specifically, one of the second NMOS transistor Q2 and the third NMOS transistor Q3 is turned on or off in response to the second pulse width modulation signal, and the other remains off to boost or buck the bus voltage VBUS and charge the battery B1 based on the boosted or bucked voltage to store energy.

[0053] The second control unit 22 includes at least one processor 221 and a memory 222, wherein the memory 222 can be built into the second control unit 22 or externally located outside the second control unit 22. The memory 222 can also be a remotely located memory connected to the second control unit 22 via a network.

[0054] The memory 222 is a non-volatile computer-readable storage medium that can be used to store non-volatile software programs, non-volatile computer executable programs, and modules. The memory 222 may include a program storage area and a data storage area, wherein the program storage area may store an operating system and application programs required for at least one function; the data storage area may store data created based on the use of the terminal, etc. In addition, the memory 222 may include a high-speed random access memory and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some embodiments, the memory 222 may optionally include a memory remotely located relative to the processor 221, and these remote memories may be connected to the terminal via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0055] The processor 221 performs various functions of the terminal and processes data by running or executing software programs and / or modules stored in the memory 222, and calling data stored in the memory 222, thereby monitoring the terminal as a whole, for example, implementing the steps performed by the energy storage device 20 in the duty cycle adjustment method in any embodiment of the present application.

[0056] The processor 221 may be one or more, Figure 3 In the figure, a processor 221 is used as an example. The processor 221 and the memory 222 may be connected via a bus or other means. The processor 221 may include a central processing unit (CPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a controller, a field-programmable gate array (FPGA), etc. The processor 221 may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration.

[0057] Please refer to Figure 4 , Figure 4 Flowchart of the duty cycle adjustment method provided in the embodiment of the present application. The duty cycle adjustment method is used to adjust the duty cycle (denoted as the first duty cycle D1) of a first pulse width modulation signal applied to a charging device, wherein the charging device is connected to a power source. In some embodiments, the charging device can be Figure 1-Figure 3 The structural implementation shown in the figure has been described in detail in the above embodiment and will not be repeated here. Figure 4 As shown, the duty cycle adjustment method includes the following steps:

[0058] Step S410: Determine whether the charging device is loaded.

[0059] This embodiment of the present application also provides a step for determining whether the charging device 10 is loaded. Specifically, the duty cycle adjustment method further includes the following steps: obtaining the output current (i.e., the first output current) and the output voltage of the charging device 10; determining that the charging device 10 is unloaded if the output current remains zero for a duration greater than a preset duration; and determining that the charging device 10 is loaded if the output current is greater than zero and the output voltage of the charging device 10 sampled in the current sampling period is greater than the output voltage of the charging device 10 sampled in the previous sampling period. In some embodiments, the preset duration is configured as the product of the ratio of a preset maximum value of the first duty cycle D1 (i.e., the maximum duty cycle) to a first preset incremental value and the adjustment period.

[0060] When it is determined that the charging device is loaded, subsequent steps S420 to S430 are executed.

[0061] Step S420: adjusting the first duty cycle to gradually increase according to the target duty cycle and the output voltage of the power supply until the first duty cycle is greater than or equal to the target duty cycle and / or the output voltage of the power supply is less than or equal to the minimum output voltage of the power supply.

[0062] The target duty cycle is a preset target value of the duty cycle, which can be set according to the actual application scenario. In some embodiments, the target duty cycle is determined based on the ratio of the output voltage of the charging device to the input voltage of the charging device (i.e., the output voltage of the power supply) (1 / K), where K is greater than 0 and less than 1. Figure 3 The circuit structure of the charging device 10 shown, when operating in continuous conduction mode (CCM), has a ratio of the output voltage to the input voltage of the charging device 10 equal to a first duty cycle D1. The target duty cycle is determined by dividing this ratio by 1 / K. This allows the first duty cycle D1 to approach the duty cycle corresponding to the target maximum power when the first duty cycle D1 is greater than or equal to the target duty cycle and / or the output voltage of the power supply 30 is less than or equal to the minimum output voltage, thereby facilitating subsequent rapid tracking to the target maximum power. The target maximum power is the maximum value of the average output power over a regulation cycle. In one specific embodiment, when the power supply 30 is a photovoltaic module, K is set to 0.8.

[0063] Specifically, after the charging device 10 begins operation, the first duty cycle D1 is gradually increased based on the target duty cycle and the output voltage of the power source 30 (here, the actual output voltage of the power source 30). (It should be understood that when the first duty cycle D1 is gradually increased, the current value of the first duty cycle D1 is adjusted.) This can be achieved by reducing the rate of increase of the first duty cycle D1, i.e., initially increasing the first duty cycle D1 at a slower rate. This prevents over-adjustment of the first duty cycle D1 during the adjustment process, thereby preventing over-adjustment of the output voltage of the power source 30 and the occurrence of an abnormal situation where the output voltage of the power source 30 continuously decreases. If the power source 30 is a photovoltaic module, this can improve the stability of the photovoltaic module's operation and ensure stable power supply. Furthermore, based on experience, the target duty cycle can be set close to the first duty cycle D1 corresponding to the target maximum power. Subsequently, after the first duty cycle D1 is gradually increased, the first duty cycle D1 corresponding to the target maximum power can be quickly adjusted.

[0064] It is understood that after the charging device 10 begins operation, if the output voltage of the power supply 30 is greater than its minimum value (i.e., the minimum output voltage that the power supply 30 can output during normal operation), it is determined that the power supply 30 can normally provide voltage. In this case, it is sufficient to gradually increase the first duty cycle D1 according to the target duty cycle. Of course, during the process of gradually increasing the first duty cycle D1, if the output voltage of the power supply 30 becomes less than or equal to its minimum value, thus confirming that the power supply 30 cannot normally provide voltage, the gradual increase of the first duty cycle D1 should be stopped to prevent the abnormal situation of the output voltage of the power supply 30 continuously decreasing.

[0065] In some embodiments, as Figure 5 As shown, the specific implementation process of step S420 includes the following steps:

[0066] Step S510: In each adjustment cycle, when the first duty cycle is less than the target duty cycle and the output voltage of the power supply is greater than the minimum output voltage, adjust the first duty cycle to the sum of the first duty cycle and the first preset increase value to gradually increase the first duty cycle.

[0067] The first preset increase value is a preset increase value of the first duty cycle D1, which can be set according to the actual application scenario. The first preset increase value is the increase value of each adjustment cycle. The larger the first preset increase value, the faster the increase rate of the first duty cycle D1; conversely, the smaller the first preset increase value, the slower the increase rate of the first duty cycle D1. The first preset increase value of different adjustment cycles can be the same or different.

[0068] In a specific embodiment, the first preset increase value is recorded as DA and remains unchanged, the target duty cycle is recorded as DT, the output voltage of the power supply 30 is recorded as VR, and the minimum output voltage of the power supply 30 is recorded as VRM. Then, assuming that in the first adjustment cycle, D1VRM, then D1=D1+DA, the duty cycle is increased for the first time, and the increased first duty cycle D1 is applied to the charging device 10, entering the second adjustment cycle; in the second adjustment cycle, D1VRM, then D1=D1+DA, the duty cycle is increased for the second time, and the increased first duty cycle D1 is applied to the charging device 10, entering the third adjustment cycle; ...; and so on, until D1≥DT and / or VR≤VRM, then the duty cycle adjustment stops, that is, step S420 is stopped.

[0069] In some embodiments, after executing step S510 of adjusting the first duty cycle to the sum of the first duty cycle and the first preset increase value, the duty cycle adjustment method also includes the following steps: when the average value of the output power of the current adjustment cycle is greater than the recorded maximum power, the average value of the output power of the current adjustment cycle is recorded as the maximum power, and the adjusted first duty cycle is recorded as the first duty cycle corresponding to the maximum power.

[0070] The recorded maximum power refers to the highest output power value recorded in all previous adjustment cycles since the charging device 10 began operating. It is understood that the maximum power is also obtained by averaging the output power over a single adjustment cycle. The adjusted first duty cycle D1 is the sum of the first duty cycle D1 and the first preset increase value.

[0071] Specifically, after each adjustment of first duty cycle D1 to the sum of first duty cycle D1 and the first preset increase value, the adjusted first duty cycle D1 is applied to charging device 10, and the average output power of the current adjustment cycle is determined. If the average output power of the current adjustment cycle is greater than the recorded maximum power, the average output power of the current adjustment cycle is recorded as the maximum power. This allows the maximum power to be continuously updated in real time based on actual application conditions, facilitating the subsequent faster determination of the target maximum power that the photovoltaic module can provide.

[0072] In some embodiments, as Figure 6 As shown, before executing step S420, the duty cycle adjustment method further includes the following steps: determining whether the preliminary adjustment process of the first duty cycle has been completed. If it is determined that the preliminary adjustment process of the first duty cycle has not been completed, step S420 is executed; if it is determined that the preliminary adjustment process of the first duty cycle has been completed, step S430 is executed. Correspondingly, after executing step S420, the duty cycle adjustment method further includes the following steps: determining that the preliminary adjustment process of the first duty cycle has been completed, and recording the adjusted first duty cycle as the first duty cycle corresponding to the maximum power.

[0073] Specifically, the preliminary adjustment process of the first duty cycle D1 refers to a process of gradually increasing the first duty cycle D1. Completion of this process corresponds to the first duty cycle D1 being greater than or equal to the target duty cycle and / or the output voltage of the power supply 30 being less than or equal to the minimum output voltage. Incompleteness of this process corresponds to the first duty cycle D1 being less than the target duty cycle and the output voltage of the power supply 30 being greater than the minimum output voltage. If the preliminary adjustment process of the first duty cycle D1 has not yet been completed, step S420 is executed until the first duty cycle D1 is greater than or equal to the target duty cycle and / or the output voltage of the power supply 30 is less than or equal to the minimum output voltage. Thereafter, the preliminary adjustment process of the first duty cycle D1 is determined to be complete, and the adjusted first duty cycle D1 is recorded as the first duty cycle D1 corresponding to the maximum power. Thus, after the charging device 10 begins operation, the first duty cycle D1 is adjusted and gradually increased based on the target duty cycle and the output voltage of the power source 30. During this process, the adjustment range of the first duty cycle D1 is small, so that the increase rate of the first duty cycle D1 is slow, thereby preventing excessive adjustment of the duty cycle and the abnormal situation of continuously lowering the output voltage of the power source 30. When the power source 30 is a photovoltaic module, this helps improve the stability of the photovoltaic module's operation and provide stable power supply.

[0074] Afterwards, since it is determined in the current adjustment cycle that the preliminary adjustment of the first duty cycle D1 has been completed, step S430 is performed in the next adjustment cycle.

[0075] Step S430: Adjust the first duty cycle according to the output power of the power supply and the disturbance direction when the first duty cycle is disturbed, wherein when the average value of the output power in the current adjustment cycle decreases relative to the average value of the output power in the previous adjustment cycle, the disturbance direction is the first direction, and the length of the adjustment cycle is the length of time it takes to adjust the first duty cycle once.

[0076] Perturbing the first duty cycle D1 involves applying a disturbance (typically a small disturbance) to the first duty cycle D1, either increasing or decreasing it, and observing the resulting change in the output of the charging device 10 (e.g., power, voltage, current, etc.; in this embodiment, power is used as an example). Based on the output response (i.e., the change in the output power of the power source 30), it is determined whether the actual direction of the disturbance is the first direction, and further, whether to continue adjusting the first duty cycle D1, thereby gradually approaching the optimal operating point of the charging device 10.

[0077] In some embodiments, as Figure 7 As shown, the specific implementation process of step S430 includes the following steps:

[0078] Step S710: When it is determined that the disturbance direction of the current adjustment period is the first direction, the average value of the output power of the current adjustment period is recorded as the maximum power, and the direction of the disturbance amount for disturbing the first duty cycle is adjusted to the reverse direction, and the disturbance direction is adjusted not to the first direction.

[0079] Specifically, when the current disturbance direction is the first direction and the first duty cycle D1 corresponding to the current regulation cycle is applied to the charging device 10, the average output power of the current regulation cycle decreases relative to the average output power of the previous regulation cycle. Furthermore, the target maximum power may have been exceeded at this point. In this case, the average output power of the current regulation cycle is recorded as the maximum power, and the direction of the disturbance applied to the first duty cycle D1 is adjusted in the opposite direction, in the expectation that the average output power of the next regulation cycle will increase relative to the average output power of the current regulation cycle, thereby reapproaching the target maximum power.

[0080] It can be understood that the disturbance amount in the embodiment of the present application includes a direction and a value, that is, the disturbance amount can be a positive value or a negative value. For example, assuming that before executing step S710, the disturbance amount is a value greater than 0 (such as P1), disturbing the first duty cycle D1 means increasing the first duty cycle D1; and after executing step S710, the direction of the disturbance amount is adjusted to the reverse direction, then the disturbance amount is a value less than 0 (-P1), and disturbing the first duty cycle D1 means decreasing the first duty cycle D1.

[0081] In some embodiments, as Figure 8 As shown, the specific implementation process of step S430 includes the following steps:

[0082] Step S810: Determine that the disturbance direction of the current adjustment period is not the first direction.

[0083] Among them, step S710 and step S810 can be either parallel steps or progressive steps. That is, when step S810 and step S710 are parallel steps, if the current disturbance direction is not the first direction, steps S810 to S830 are executed; if the current disturbance direction is the first direction, step S710 is executed. When step S710 and step S810 are progressive steps, step S710 is executed first, and since the disturbance direction has been adjusted to not the first direction, steps S810 to S830 are executed.

[0084] When it is determined that the disturbance direction of the current adjustment period is not the first direction, step S820 and step S830 are executed.

[0085] Step S820: If the average value of the output power in the current adjustment period is less than the recorded maximum power, or the current value of the output voltage of the power supply is less than the minimum value, then the disturbance direction is adjusted to the first direction.

[0086] Specifically, if the average value of the output power in the current adjustment cycle is less than the recorded maximum power, it can be determined that, when the disturbance direction is not the first direction, the average value of the output power in the current adjustment cycle has decreased relative to the average value of the output power in the previous adjustment cycle after the disturbance. In this case, the disturbance direction should be adjusted from not the first direction to the first direction, in order to expect the average value of the output power in the next adjustment cycle to increase relative to the average value of the output power in the current adjustment cycle, thereby approaching the target maximum power.

[0087] The fact that the current value of the output voltage of power supply 30 is less than the minimum value indicates that, if the perturbation direction is not the first direction, the perturbation will cause the current value of the output voltage in the current cycle to be less than the minimum value, and power supply 30 will not be able to provide voltage normally. In this case, the perturbation direction should be adjusted from the non-first direction to the first direction in the hope that power supply 30 will be able to provide voltage normally in the next regulation cycle, thereby preventing the abnormal situation of the output voltage of power supply 30 continuously decreasing.

[0088] Step S830: If the average value of the output power of the current adjustment cycle is greater than or equal to the recorded maximum power, and the current value of the output voltage of the power supply is greater than or equal to the minimum value, then the average value of the output power of the current adjustment cycle is recorded as the maximum power, and the first duty cycle is adjusted to the sum of the first duty cycle and the disturbance amount.

[0089] If the output voltage of power supply 30 is greater than or equal to the minimum output voltage, it can be determined that power supply 30 can maintain normal voltage supply. Furthermore, if the average output power value of the current adjustment cycle is greater than or equal to the recorded maximum power, it can be determined that, when the perturbation direction is not the first direction, the average output power value of the current adjustment cycle has increased relative to the average output power value of the previous adjustment cycle after the perturbation. In this case, the perturbation direction should be maintained unchanged, and the first duty cycle D1 should continue to be perturbed, that is, the first duty cycle D1 should be adjusted to the sum of the first duty cycle D1 and the perturbation amount to approach the target maximum power.

[0090] In some embodiments, the absolute value of the disturbance amount is greater than the first predetermined increase value. Thus, after the charging device 10 begins operating, the first duty cycle D1 is initially increased at a relatively slow rate to prevent the abnormal situation of the output voltage of the photovoltaic module from continuously decreasing. Thereafter, the first duty cycle D1 is disturbed at a relatively fast rate to quickly approach the target maximum power.

[0091] In some embodiments, as Figure 9As shown, after executing step S430, the duty cycle adjustment method further includes the following steps:

[0092] Step S910: When the first duty cycle is greater than the maximum duty cycle, adjust the disturbance direction to the first direction, and set the first duty cycle to the maximum duty cycle.

[0093] Step S920: When the first duty cycle is smaller than the maximum duty cycle and smaller than the minimum duty cycle, the disturbance direction is adjusted to the first direction, and the first duty cycle is set to the minimum duty cycle.

[0094] The maximum duty cycle is the preset upper limit of the duty cycle, and the minimum duty cycle is the preset lower limit of the duty cycle. Both can be set based on actual application scenarios, with the minimum duty cycle being smaller than the maximum duty cycle. Setting the maximum duty cycle prevents abnormal situations where the output voltage or current of the charging device 10 exceeds its tolerable range due to an excessively high first duty cycle D1, thereby damaging the charging device 10. Setting the minimum duty cycle prevents the charging device 10 from entering an undesirable operating state (such as excessively low output power or low efficiency), thereby ensuring that the charging device 10 operates within a safe and efficient range.

[0095] Specifically, if the first duty cycle D1 is greater than the maximum duty cycle, it is determined that the first duty cycle D1 of the current adjustment cycle is too large. In this case, the first duty cycle D1 is set to the maximum duty cycle. At the same time, the disturbance direction is adjusted to the first direction so that step S710 can be executed in the next adjustment cycle. According to the above description, it can be seen that by executing step S710, the target maximum power can be re-approximated. In summary, the first duty cycle D1 is adjusted to approach the target maximum power while ensuring that the first duty cycle D1 is less than or equal to the maximum duty cycle.

[0096] If the first duty cycle D1 is less than the minimum duty cycle, it is determined that the first duty cycle D1 of the current adjustment cycle is too small. In this case, the first duty cycle D1 is set to the minimum duty cycle. At the same time, the perturbation direction is adjusted to the first direction so that step S710 can be performed in the next adjustment cycle to re-approximate the target maximum power. In summary, the duty cycle is adjusted to approach the target maximum power while ensuring that the first duty cycle D1 is greater than the minimum duty cycle.

[0097] Afterwards, step S440 to step S450 are executed.

[0098] Step S440: generating a maximum output current of the charging device according to the output voltage of the charging device and the maximum output voltage of the charging device.

[0099] Step S450: generating a second duty cycle according to the maximum output current and the first output current of the charging device.

[0100] Specifically, according to step S440 and step S450 , the constant voltage and current limiting functions can be achieved.

[0101] In some embodiments, as Figure 10 As shown, the specific implementation process of step S440 and step S450 includes the following steps:

[0102] Step S1010: performing PI regulation on the difference between the output voltage of the charging device and the maximum output voltage to generate the maximum output current.

[0103] Step S1020: performing PI regulation on the difference between the maximum output current and the first output current to generate a second duty cycle.

[0104] The specific implementation process is as follows Figure 11 PI regulation is performed based on the difference VOUT_ER between the maximum output voltage VOUT_REF and the output voltage VOUT_FB of the charging device to obtain the maximum output current IOUT_REF, and then PI regulation is performed based on the difference IOUT_ER between the maximum output current IOUT_REF and the first output current IOUT_FB to obtain the second duty cycle D2.

[0105] In some embodiments, for Figure 11 The control method shown can also add a limiting unit to limit the corresponding parameters. For example, after performing PI adjustment on the difference VOUT_ER, the maximum output current IOUT_REF can be limited, and then the difference IOUT_ER between the limited maximum output current IOUT_REF and the first output current IOUT_FB can be PI adjusted.

[0106] Step S460: determining a third duty cycle according to the minimum value of the adjusted first duty cycle and the second duty cycle, and setting the first duty cycle as the third duty cycle.

[0107] Specifically, the adjusted first duty cycle D1 is the first duty cycle D1 after executing steps S910 and S920. The adjusted first duty cycle D1 is compared with the second duty cycle D2 to obtain the minimum value between the two, which is the third duty cycle D3. The first duty cycle D1 is set to the third duty cycle D3, i.e., the third duty cycle D3 is applied to the charging device 10, thereby achieving the functions of constant voltage, current limiting, and maximum target power tracking.

[0108] It is understandable that if only Figure 11With the aforementioned control method, when photovoltaic power is low, the output current of the charging device 10 never reaches its maximum value. That is, the currents IOUT_REF and IOUT_FB remain unequal, and the difference IOUT_ER persists. Based on PI regulation, the second duty cycle D2 continuously increases in an attempt to increase the output current of the charging device 10. Consequently, the output voltage of the charging device 10 continuously decreases, potentially falling below the minimum operating voltage of the charging device 10. Consequently, the charging device 10 cannot function properly and cannot track the maximum power of the PV panels.

[0109] By adopting the control method provided in this application, on the one hand, when the charging device 10 is loaded and operating normally, the second duty cycle D2 is generally greater than the adjusted first duty cycle D1, that is, the adjusted first duty cycle D1 is directly applied to the charging device 10. Specifically, during the adjustment of the first duty cycle D1, the first duty cycle D1 is initially increased at a slower rate, thereby preventing the abnormal situation of the photovoltaic module output voltage continuously decreasing, thereby improving the stability of the photovoltaic module operation and ensuring stable power supply. Subsequently, when the photovoltaic module is providing stable power, the maximum power of the photovoltaic module can be more reliably tracked based on the output power and the disturbance direction. On the other hand, when the charging device 10 is loaded and an abnormality occurs, such as a current exceeding the limit, the second duty cycle D2 is generally smaller and less than the adjusted first duty cycle D1, in such a case, to achieve constant voltage and current limiting functions, thereby maintaining stable and reliable operation of the charging device 10.

[0110] Please refer to Figure 12 , Figure 12 This is a flow chart of a duty cycle adjustment method provided by another embodiment of the present application. Figure 12 As shown, at the beginning of the adjustment cycle, it is determined whether the charging device 10 is loaded. When the charging device 10 is loaded, it is determined whether the target duty cycle has not been set. If the target duty cycle has not been set, the target duty cycle is determined based on 1 / K of the ratio of the output voltage of the charging device 10 to the input voltage of the charging device 10, and it is determined that the target duty cycle has been set. If the target duty cycle has been set, it is determined whether the preliminary adjustment process of the first duty cycle D1 has not been completed.

[0111] If the preliminary adjustment process of the first duty cycle D1 is not completed, the process of gradually increasing the first duty cycle D1 is performed according to the target duty cycle and the output voltage of the power supply 30. The specific implementation process is as follows:

[0112] First, it is determined whether the first duty cycle D1 is smaller than the target duty cycle, and whether the output voltage of the power supply 30 is greater than the minimum output voltage.

[0113] If the first duty cycle D1 is less than the target duty cycle, and the output voltage of the power supply 30 is greater than the minimum output voltage, the first duty cycle D1 is adjusted to the sum of the first duty cycle D1 and the first preset increase value. Next, a determination is made as to whether the average value of the output power of the current adjustment cycle is greater than the recorded maximum power. If the average value of the output power of the current adjustment cycle is greater than the recorded maximum power, the average value of the output power of the current adjustment cycle is recorded as the maximum power, and the adjusted first duty cycle D1 is recorded as the first duty cycle D1 corresponding to the maximum power, and the current adjustment cycle ends. If the average value of the output power of the current adjustment cycle is less than or equal to the recorded maximum power, the current adjustment cycle ends.

[0114] If the first duty cycle D1 is greater than or equal to the target duty cycle, and / or the output voltage of the power supply 30 is less than or equal to the minimum output voltage, it is determined that the preliminary adjustment process of the first duty cycle D1 has been completed, and the adjusted first duty cycle D1 is recorded as the first duty cycle D1 corresponding to the maximum power, and the current adjustment cycle ends.

[0115] If the preliminary adjustment process of the first duty cycle D1 is completed, the process of adjusting the first duty cycle D1 according to the first output power and the disturbance direction when the first duty cycle D1 is disturbed is performed. The specific implementation process is as follows:

[0116] First, determine whether the disturbance direction of the current adjustment cycle is the first direction. If the disturbance direction of the current adjustment cycle is the first direction, record the average value of the output power of the current adjustment cycle as the maximum power, adjust the direction of the disturbance amount for disturbing the first duty cycle D1 to the reverse direction, and adjust the disturbance direction to not be the first direction. If the disturbance direction of the current adjustment cycle is not the first direction, determine whether the average value of the output power of the current adjustment cycle is less than the recorded maximum power and determine whether the output voltage of the power supply 30 is less than the minimum output voltage. If the average value of the output power of the current adjustment cycle is less than the recorded maximum power, or the output voltage of the power supply 30 is less than the minimum output voltage, adjust the disturbance direction to the first direction. If the average value of the output power of the current adjustment cycle is greater than or equal to the recorded maximum power, and the output voltage of the power supply 30 is greater than or equal to the minimum output voltage, record the average value of the output power of the current adjustment cycle as the maximum power, and adjust the first duty cycle D1 to the sum of the first duty cycle D1 and the disturbance amount.

[0117] After that, it is determined whether the first duty cycle D1 is greater than the maximum duty cycle. If the first duty cycle D1 is greater than the maximum duty cycle, the perturbation direction is adjusted to the first direction, and the first duty cycle D1 is set to the maximum duty cycle, and the current adjustment period ends. If the first duty cycle D1 is less than or equal to the maximum duty cycle, it is further determined whether the first duty cycle D1 is less than the minimum duty cycle. If the first duty cycle D1 is less than the minimum duty cycle, the perturbation direction is adjusted to the first direction, and the first duty cycle D1 is set to the minimum duty cycle, and the current adjustment period ends. If the first duty cycle D1 is greater than or equal to the minimum duty cycle, the current adjustment period ends.

[0118] In summary, the first duty cycle D1 corresponding to the maximum power is obtained. In this process, after the start of the current adjustment period, first, according to the target duty cycle and the output voltage of the power supply 30, the first duty cycle D1 is adjusted to gradually increase. Then, by reducing the rate of increase of the first duty cycle D1, the first duty cycle D1 can be raised at a slower growth rate at the beginning. Thus, during the process of adjusting the first duty cycle D1, there will be no over-adjustment of the first duty cycle D1, which will not lead to over-adjustment of the output voltage of the power supply 30, and will not cause the abnormal situation that the output voltage of the power supply 30 continues to drop. When the power supply 30 is a photovoltaic module, it is beneficial to improve the working stability of the photovoltaic module to supply power stably. Second, the target duty cycle can also be set according to experience to be close to the first duty cycle D1 corresponding to the target maximum power. Subsequently, after the process of gradually increasing the first duty cycle D1 is completed, the first duty cycle D1 corresponding to the target maximum power can be quickly adjusted. Moreover, in the subsequent adjustment process, by applying a perturbation amount to the first duty cycle D1 and adjusting the first duty cycle D1 in real time according to the perturbation direction and the output power of the power supply 30, the approximation of the target maximum power can be achieved, and the perturbation rate is fast and the adjustment time is short.

[0119] At the same time, for the charging device 10, a constant output voltage needs to be maintained and the maximum output current needs to be limited. Based on this, the charging device 10 also adopts Figure 11 the control method shown to obtain the second duty cycle D2 corresponding to the constant voltage and current limiting function, and the operation period for obtaining the second duty cycle D2 by adopting this control method is Tn.

[0120] The operation period of the foregoing method for obtaining the first duty cycle D1 is Tm (i.e., the foregoing adjustment period), and Tm < Tn. After the two duty cycles are obtained, a comparison needs to be made, and the smaller of the two duty cycles is applied to the charging device 10. Thus, the charger 10 simultaneously has the functions of constant voltage and current limiting and tracking the maximum target power.

[0121] It should be noted that the steps shown as Figure 5-Figure 11 are all executed by the charging device 10.

[0122] In the above embodiments, all the method steps are performed when the charging device 10 is loaded. When the charging device 10 is not loaded (i.e., no-load), the charging device 10 only needs to maintain a constant output voltage and needs to limit the maximum output current. Based on this, when the charging device 10 is no-load, you can use Figure 11 The control method shown is used to obtain the second duty cycle D2 of the first pulse width modulation signal, and the second duty cycle D2 is applied to the charging device 10.

[0123] like Figure 13 As shown, the duty cycle adjustment method also includes the following steps:

[0124] Step S1310: the energy storage device generates a disturbance signal corresponding to the maximum bus voltage.

[0125] The maximum bus voltage is a preset upper limit for the bus voltage, which can be set based on actual application scenarios. The maximum bus voltage is determined based on the maximum allowable input voltage of the energy storage device 20 and can be set to be less than or equal to the maximum allowable input voltage of the energy storage device 20. If the voltage input to the energy storage device 20 does not exceed the maximum input voltage, the energy storage device 20 will not be damaged by overvoltage, thus preventing irreversible damage to its internal circuits and other components.

[0126] The disturbance signal corresponding to the maximum bus voltage means that the maximum bus voltage and the disturbance signal have a pre-set mapping relationship. Based on the maximum bus voltage and the mapping relationship, the disturbance signal corresponding to the maximum bus voltage can be obtained. Of course, if the disturbance signal is determined first, the maximum bus voltage corresponding to the disturbance signal can also be determined based on the disturbance signal and the mapping relationship.

[0127] In some embodiments, as Figure 14 As shown, the specific implementation process of step S1310 includes the following steps:

[0128] Step S1410: The energy storage device determines the frequency or peak value corresponding to the maximum bus voltage.

[0129] Specifically, the frequency (or peak value) corresponding to the maximum bus voltage refers to a pre-set mapping relationship between the maximum bus voltage and the frequency (or peak value). Based on the maximum bus voltage and the mapping relationship, the frequency (or peak value) corresponding to the maximum bus voltage can be obtained. Of course, if the frequency (or peak value) is determined first, the maximum bus voltage corresponding to the frequency (or peak value) can also be determined based on the frequency (or peak value) and the mapping relationship.

[0130] Step S1420: The energy storage device generates a disturbance signal according to the frequency or peak value.

[0131] In some embodiments, the specific implementation process of the energy storage device generating the disturbance signal according to the frequency is: the energy storage device generates the disturbance signal according to the product of the sine value corresponding to the frequency and the preset duty cycle.

[0132] The sine value corresponding to the frequency can be expressed as: sinθ, where θ = 2π*Freq*T, where Freq is the frequency and T is the preset duration. The preset duration can be determined based on the operation period when the energy storage device 20 performs the duty cycle adjustment method. For example, in one specific embodiment, T is set to T = t*Ts, where Ts is the operation period and t is a coefficient greater than zero. Therefore, the disturbance signal is: DutyS*sinθ, where DutyS is the preset duty cycle.

[0133] In some embodiments, the preset duty cycle can be set by Figure 15 The steps shown are implemented. Figure 15 As shown, the duty cycle adjustment method also includes the following steps:

[0134] Step S1510: The energy storage device determines the AC component according to the bus voltage.

[0135] Step S1520: The energy storage device determines a peak value based on the AC component.

[0136] The bus voltage in step S1510 refers to the bus voltage after the disturbance signal acts on the fourth duty cycle D4 of the second pulse width modulation signal. The bus voltage at this time includes a DC component and an AC component.

[0137] Figure 16 The following example shows a way for the energy storage device to determine the DC component, AC component, peak value and frequency according to the bus voltage. Figure 16As shown, the bus voltage VBUS is filtered through a low-pass filter to generate a DC component VBUS_DC. The difference between the bus voltage VBUS and the DC component VBUS_DC is calculated to obtain the AC component VBUS_AC. The AC component VBUS_AC is passed through a second-order generalized integrator (SOGI) phase-locked loop (PLL) to obtain the peak value VBUS_A and the frequency VBUS_F. A second-order generalized integrator (SOGI) phase-locked loop (PLL) is a PLL technology used in power systems to extract the frequency and peak value of voltage. The second-order generalized integrator (SOGI) decomposes the input signal into in-phase and quadrature components. In the SOGI-PLL, the quadrature signals generated by the SOGI are fed into the control section of the phase-locked loop (PLL). The control section calculates the peak value of the quadrature signals and uses a proportional-integral (PI) controller to adjust the output of the local oscillator to synchronize its frequency with the voltage, thereby obtaining the frequency.

[0138] Step S1530: The energy storage device generates a preset duty cycle according to the maximum AC component and the peak value, so that the AC component is less than or equal to the maximum AC component.

[0139] The maximum AC component is a preset maximum value of the AC component, which can be set based on actual application scenarios. By controlling the actual value of the AC component to be less than or equal to the maximum AC component, it is possible to ensure that after the disturbance signal acts on the fourth duty cycle D4 of the second pulse-width modulation signal, the change in bus voltage remains within an acceptable range (for example, such change will not cause damage to the energy storage device and the charging device), thereby ensuring stable operation of the energy storage device 20 and the charging device 10.

[0140] In one specific embodiment, step S1530 is implemented as follows: the energy storage device performs PI regulation on the difference between the maximum AC component and the peak value to generate a preset duty cycle. Through PI regulation, the difference is gradually reduced, and the preset duty cycle gradually increases. When the difference decreases to 0, the preset duty cycle reaches its maximum value, and the peak value of the AC component equals the maximum AC component. Therefore, maintaining the actual value of the AC component less than or equal to the maximum AC component helps ensure stable operation of the energy storage device 20 and the charging device 10.

[0141] In some embodiments, after generating a preset duty cycle, the duty cycle adjustment method further includes the step of limiting the preset duty cycle. The specific implementation process of the energy storage device generating a disturbance signal based on the frequency is as follows: the energy storage device generates the disturbance signal based on the product of the sine value corresponding to the frequency and the preset duty cycle after limiting.

[0142] Step S1320: the energy storage device applies the disturbance signal to the fourth duty cycle of the second pulse width modulation signal, so that the bus voltage includes a DC component and an AC component corresponding to the disturbance signal.

[0143] The disturbance signal acting on the fourth duty cycle D4 of the second pulse-width modulation signal refers to combining the disturbance signal and the fourth duty cycle D4. The specific combination method can be set according to the actual application scenario. The fourth duty cycle D4 is updated based on the result of the combination, that is, the updated fourth duty cycle D4 is the result of the combination. The updated fourth duty cycle D4 is applied to the switching transistor in the energy storage device 20. Thereafter, the bus voltage VBUS will include a DC component and an AC component corresponding to the disturbance signal.

[0144] In some embodiments, the duty cycle adjustment method further includes the following steps: the energy storage device performs PI adjustment on the difference between a preset bus voltage value and an actual bus voltage value to generate a maximum input current of the energy storage device; and the energy storage device performs PI adjustment on the difference between the maximum input current value and the actual input current value to generate a fourth duty cycle of the second pulse-width modulation signal. Furthermore, the specific implementation process of step S1320 includes the following steps: the energy storage device superimposes the disturbance signal with the fourth duty cycle of the second pulse-width modulation signal.

[0145] Figure 17 The control method of the energy storage device 20 is shown as an example. Figure 17 As shown, the energy storage device 20 performs PI regulation on the difference VIN_ER between the preset given value VIN_REF of the bus voltage and the actual value VIN_FB of the bus voltage to generate the maximum value IIN_REF of the input current of the energy storage device 20; the energy storage device 20 performs PI regulation on the difference IIN_ER between the maximum value IIN_REF of the input current and the actual value IIN_FB of the input current to generate a fourth duty cycle D4 of the second pulse width modulation signal.

[0146] At the same time, the energy storage device 20 performs PI regulation on the difference VD_ER between the preset maximum value VD_REF and the peak value VD_FB of the AC component to generate a preset duty cycle DutyS. The disturbance signal DutyS*sinθ is generated based on the product of the sine value sinθ corresponding to the frequency and the preset duty cycle DutyS.

[0147] Finally, the fourth duty cycle D4 is superimposed on the disturbance signal DutyS*sinθ to generate a duty cycle of DutyA. DutyA is the updated duty cycle of the second pulse-width modulation signal. DutyA is applied to the switch in the energy storage device 20. The bus voltage VBUS then includes a DC component and an AC component corresponding to the disturbance signal.

[0148] In some embodiments, for Figure 17 The control method shown may further include an additional limiting unit to limit corresponding parameters. For example, after performing PI adjustment on the difference VIN_ER, the maximum value IIN_REF of the input current may be limited, and then PI adjustment may be performed on the difference IIN_ER between the maximum value IIN_REF of the input current after limiting and the actual value IIN_FB of the input current. For another example, after performing PI adjustment on the difference IIN_ER, the fourth duty cycle D4 may be limited. For another example, after superimposing the fourth duty cycle D4 with the disturbance signal DutyS*sinθ, the duty cycle DutyA may be limited, and then the limited duty cycle DutyA may be applied to the switch tube in the energy storage device 20.

[0149] Step S1330: The charging device determines the AC component according to the bus voltage.

[0150] The bus voltage here includes a DC component and an AC component corresponding to the disturbance signal. Since the charging device 10 is connected to the bus, the charging device 10 can obtain the bus voltage and then obtain the AC component from the bus voltage.

[0151] In some embodiments, the specific implementation process of step S1330 includes the following steps: filtering the bus voltage to obtain a DC component; and determining an AC component based on the difference between the bus voltage and the DC component.

[0152] Specifically, Figure 16 As shown, the bus voltage VBUS is filtered by a low-pass filter unit to generate a DC component VBUS_DC; the AC component VBUS_AC is obtained by calculating the difference between the bus voltage VBUS and the DC component VBUS_DC.

[0153] Step S1340: The charging device controls the voltage output by the charging device according to the AC component so that the voltage output by the charging device is less than or equal to the maximum bus voltage.

[0154] Specifically, since the AC component and the disturbance component have a mapping relationship, and the disturbance component has a mapping relationship with the maximum bus voltage, the AC component and the maximum bus voltage also have a mapping relationship. Therefore, once the charging device 10 determines the AC component, it also determines the maximum bus voltage. On this basis, the charging device 10 can control its output voltage to be less than or equal to the maximum bus voltage. This shows that for different energy storage devices, the charging device can ensure that its output voltage does not exceed the maximum input voltage allowed by the energy storage device, making the charging device compatible with different energy storage devices.

[0155] In some embodiments, as Figure 18As shown, the specific implementation process of step S1340 includes the following steps:

[0156] Step S1810: The charging device determines the frequency corresponding to the AC component according to the AC component.

[0157] Step S1820: The charging device determines the maximum bus voltage according to the frequency.

[0158] Step S1830: The charging device controls the second duty cycle according to the maximum bus voltage to control the voltage output by the charging device to be less than or equal to the maximum bus voltage.

[0159] For the embodiment in which the energy storage device generates a disturbance signal according to the product of the sine value corresponding to the frequency and the preset duty cycle, first, the method can be used. Figure 16 In the illustrated method, the AC component VBUS_AC is passed through a second-order generalized integrator-based phase-locked loop (PLL) to obtain the frequency VBUS_F. The maximum bus voltage corresponding to that frequency is then determined based on the frequency and a mapping relationship (i.e., the mapping relationship between the maximum bus voltage and frequency). Based on this, the charger 10 can control the second duty cycle D2 based on the maximum bus voltage to keep the output voltage of the charger 10 less than or equal to the maximum bus voltage.

[0160] In some embodiments, as Figure 19 As shown, the specific implementation process of step S1830 includes the following steps:

[0161] Step S1910 : The charging device performs PI regulation on the difference between the maximum bus voltage and the actual value of the bus voltage to generate the maximum output current of the charging device.

[0162] Step S1920: The charging device performs PI regulation on the difference between the maximum output current and the actual value of the output current to generate a second duty cycle.

[0163] Specific control process such as Figure 11 At this time, the maximum output voltage VOUT_REF corresponds to the maximum bus voltage, the output voltage VOUT_FB of the charging device corresponds to the actual value of the bus voltage, the maximum output current IOUT_REF corresponds to the maximum output current of the charging device, and the first output current IOUT_FB corresponds to the actual value of the output current.

[0164] The above description is merely an embodiment of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

[0165] The above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them. Based on the concept of the present application, the technical features in the above embodiments or different embodiments may be combined, and the steps may be implemented in any order. A person skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some of the technical features may be replaced by equivalents. However, such modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A duty cycle adjustment method, characterized in that: For adjusting a first duty cycle of a first pulse width modulation signal applied to a charging device, the charging device being connected to a power source, the method comprising: When determining that the charging device is loaded, perform the following steps: adjusting the first duty cycle to gradually increase according to a target duty cycle and the output voltage of the power supply until the first duty cycle is greater than or equal to the target duty cycle and / or the output voltage of the power supply is less than or equal to a minimum output voltage of the power supply; adjusting the first duty cycle according to the output power of the power supply and a disturbance direction when the first duty cycle is disturbed, wherein when the average value of the output power in a current adjustment period decreases relative to the average value of the output power in a previous adjustment period, the disturbance direction is the first direction, and the duration of the adjustment period is the duration of adjusting the first duty cycle once; generating a maximum output current of the charging device according to the output voltage of the charging device and the maximum output voltage of the charging device; generating a second duty cycle according to the maximum output current and the first output current of the charging device; A third duty cycle is determined according to a minimum value between the adjusted first duty cycle and the second duty cycle, and the first duty cycle is set as the third duty cycle.

2. The method according to claim 1, characterized in that The step of adjusting the first duty cycle to gradually increase according to the target duty cycle and the output voltage of the power supply includes: In each of the adjustment cycles, when the first duty cycle is less than the target duty cycle and the output voltage of the power supply is greater than the minimum output voltage, the first duty cycle is adjusted to be the sum of the first duty cycle and a first preset increase value, so as to adjust the first duty cycle to gradually increase.

3. The method according to claim 2, characterized in that After performing the step of adjusting the first duty cycle to the sum of the first duty cycle and a first preset increase value, the method further includes: When the average value of the output power in the current adjustment cycle is greater than the recorded maximum power, the average value of the output power in the current adjustment cycle is recorded as the maximum power, and the adjusted first duty cycle is recorded as the first duty cycle corresponding to the maximum power.

4. The method according to any one of claims 1 to 3, characterized in that Before executing the step of adjusting the first duty cycle to gradually increase according to the target duty cycle and the output voltage of the power supply until the first duty cycle is greater than or equal to the target duty cycle and / or the output voltage of the power supply is less than or equal to the minimum output voltage of the power supply, the method further includes: determining whether a preliminary adjustment process of the first duty cycle has been completed; If not, performing the step of adjusting the first duty cycle to gradually increase according to the target duty cycle and the output voltage of the power supply until the first duty cycle is greater than or equal to the target duty cycle and / or the output voltage of the power supply is less than or equal to the minimum output voltage of the power supply; If yes, performing the step of adjusting the first duty cycle according to the output power of the power supply and the disturbance direction when disturbing the first duty cycle; After performing the step of adjusting the first duty cycle to gradually increase according to the target duty cycle and the output voltage of the power supply until the first duty cycle is greater than or equal to the target duty cycle and / or the output voltage of the power supply is less than or equal to the minimum output voltage of the power supply, the method further includes: Determining that a preliminary adjustment process of the first duty cycle is completed; The adjusted first duty cycle is recorded as the first duty cycle corresponding to the maximum power.

5. The method according to claim 1, wherein The method further comprises: The target duty cycle is determined according to 1 / K, which is a ratio of the output voltage of the charging device to the input voltage of the charging device, where K is greater than 0 and less than 1.

6. The method according to claim 1, wherein The step of adjusting the first duty cycle according to the output power of the power supply and the disturbance direction when the first duty cycle is disturbed includes: When it is determined that the disturbance direction of the current adjustment cycle is the first direction, the average value of the output power of the current adjustment cycle is recorded as the maximum power, and the direction of the disturbance amount for disturbing the first duty cycle is adjusted to the reverse direction, and the disturbance direction is adjusted not to the first direction.

7. The method according to claim 6, characterized in that The step of adjusting the first duty cycle according to the output power of the power supply and the disturbance direction when the first duty cycle is disturbed includes: When it is determined that the disturbance direction of the current adjustment period is not the first direction, performing the following steps: If the average value of the output power in the current adjustment period is less than the recorded maximum power, or the current value of the output voltage of the power supply is less than the minimum output voltage, adjusting the disturbance direction to the first direction; If the average value of the output power in the current adjustment cycle is greater than or equal to the recorded maximum power, and the current value of the output voltage of the power supply is greater than or equal to the minimum output voltage, the average value of the output power in the current adjustment cycle is recorded as the maximum power, and the first duty cycle is adjusted to the sum of the first duty cycle and the disturbance amount.

8. The method according to claim 1, characterized in that After performing the step of adjusting the first duty cycle according to the output power of the power supply and the disturbance direction when disturbing the first duty cycle, the method further includes: When the first duty cycle is greater than the maximum duty cycle, the disturbance direction is adjusted to the first direction, and the first duty cycle is set to the maximum duty cycle.

9. The method according to claim 1, characterized in that After performing the step of adjusting the first duty cycle according to the output power of the power supply and the disturbance direction when disturbing the first duty cycle, the method further includes: When the first duty cycle is smaller than the maximum duty cycle and the first duty cycle is smaller than the minimum duty cycle, the disturbance direction is adjusted to the first direction, and the first duty cycle is set to the minimum duty cycle.

10. The method according to claim 1, characterized in that Generating the maximum output current of the charging device according to the output voltage of the charging device and the maximum output voltage of the charging device includes: performing PI regulation on a difference between an output voltage of the charging device and the maximum output voltage to generate the maximum output current; Generating a first duty cycle according to the maximum output current and the first output current of the charging device includes: A PI regulation is performed on a difference between the maximum output current and the first output current to generate the second duty cycle.

11. A charging device, characterized in that: include: a charging circuit connected to a power source and configured to output a bus voltage based on a voltage output by the power source; A first control unit, connected to the charging circuit, configured to adjust a duty cycle of a first pulse width modulation signal applied to the charging device, comprising: at least one processor and memory; The memory is coupled to the processor, and is used to store instructions or programs. When the instructions or programs are executed by the at least one processor, the at least one processor executes the duty cycle adjustment method according to any one of claims 1 to 10.

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