Mppt control method and converter for multi-stage dc-dc topology

Abstract

This application relates to the field of photovoltaic power generation technology, and in particular to an MPPT control method, converter, and storage medium for a multi-stage DC-DC topology. The MPPT control method for the multi-stage DC-DC topology includes: sampling the DC bus voltage and photovoltaic input current; calculating three duty cycles based on the bus voltage loop, the input current loop, and a preset first formula, respectively, and selecting the smallest of the three duty cycles as the control duty cycle of the BOOST boost circuit; and calculating the control duty cycle of the BUCK buck circuit based on a preset second formula. This method, while achieving multi-voltage adaptation and flexible energy ecosystem construction, effectively solves the core problem of MPPT function inaccuracy under a multi-stage DC-DC architecture, ensuring the overall energy capture efficiency of the system under a wide range of illumination conditions.

Description

Technical Field

[0001] This application relates to the field of photovoltaic power generation technology, and in particular to an MPPT control method, converter and storage medium for a multi-level DC-DC topology. Background Technology

[0002] With the development of portable energy storage devices and photovoltaic applications, multi-stage DC-DC converters that can connect various energy devices (such as photovoltaic panels, lead-acid batteries, energy storage battery packs, portable energy storage products, etc.) into a micro-energy storage network have emerged on the market. These multi-stage DC-DC converters typically include a BOOST boost circuit and a BUCK buck circuit to enable photovoltaic panels with different voltage specifications to charge portable energy storage devices with different input voltage ranges.

[0003] In this multi-stage DC-DC topology, when only photovoltaic input is used to charge a portable energy storage device with built-in MPPT (Maximum Power Point Tracking) function through a multi-stage DC-DC converter, a special challenge will be faced: the MPPT algorithm built into the portable energy storage device is designed based on the voltage-power characteristic curve of the photovoltaic panel. If the multi-stage DC-DC converter adopts conventional closed-loop voltage regulation control, its output characteristics will mask the voltage-power characteristics of the photovoltaic panel itself, thus causing the portable energy storage device to be unable to accurately track the maximum power point.

[0004] Therefore, there is an urgent need to provide an MPPT control strategy suitable for multi-stage DC-DC topologies, which can still make the output port exhibit voltage-power characteristics similar to those of photovoltaic panels after multiple stages of conversion, thereby ensuring compatibility with the MPPT function of back-end equipment and improving the overall energy capture efficiency of the system. Summary of the Invention

[0005] The embodiments of this application aim to provide an MPPT control method, converter, and storage medium for a multi-stage DC-DC topology, in order to solve the technical problem that back-end devices cannot effectively perform MPPT in multi-stage DC-DC converters.

[0006] To address the aforementioned technical problems, this application provides the following technical solutions:

[0007] In a first aspect, embodiments of this application provide an MPPT control method for a multi-stage DC-DC topology, applied to a multi-stage DC-DC converter. The multi-stage DC-DC converter includes a BOOST boost circuit and a BUCK buck circuit connected in sequence. The BOOST boost circuit boosts the photovoltaic input voltage to the DC bus voltage, and the BUCK buck circuit bucks the DC bus voltage to the charging output voltage. The method includes:

[0008] Sample DC bus voltage and photovoltaic input current;

[0009] Three duty cycles are calculated based on the bus voltage loop, the input current loop, and a preset first formula, respectively, and the smallest of the three duty cycles is selected as the control duty cycle of the BOOST boost circuit.

[0010] The control duty cycle of the BUCK buck circuit is calculated based on the preset second formula.

[0011] Optionally, before calculating the three duty cycles based on the bus voltage loop, the input current loop, and the preset first formula, the method further includes:

[0012] Obtain the open-circuit voltage of the photovoltaic panel and the target charging output voltage set by the user;

[0013] The maximum power point voltage of the photovoltaic panel is determined based on the open-circuit voltage.

[0014] The target bus voltage is determined based on the target charging output voltage.

[0015] Optionally, the calculation of the three duty cycles based on the bus voltage loop, the input current loop, and a preset first formula includes:

[0016] Based on the DC bus voltage and the target bus voltage, a first duty cycle is obtained by performing PI control through the bus voltage loop.

[0017] Based on the photovoltaic input current and the preset input current threshold, PI control is performed through the input current loop to obtain the second duty cycle;

[0018] The third duty cycle is calculated using the first formula based on the maximum power point voltage of the photovoltaic panel and the target bus voltage.

[0019] Optionally, the input current threshold is the maximum photovoltaic input current of the photovoltaic panel.

[0020] Optionally, calculating the control duty cycle of the BUCK buck circuit based on a preset second formula includes:

[0021] Based on the target bus voltage and the target charging output voltage, the control duty cycle of the BUCK step-down circuit is calculated using a preset second formula.

[0022] Optionally, the output of the BUCK step-down circuit is connected to a portable energy storage device, which has an MPPT control function.

[0023] Optionally, the first formula is:

[0024]

[0025] in, This is the voltage at the maximum power point of the photovoltaic panel. The target bus voltage.

[0026] Optionally, the second formula is:

[0027]

[0028] in, For the target bus voltage, The output voltage is used to charge the target.

[0029] Secondly, embodiments of this application provide a DC-DC converter, comprising:

[0030] The BOOST boost circuit is used to boost the photovoltaic input voltage to the DC bus voltage;

[0031] The BUCK step-down circuit is used to step down the DC bus voltage to the charging output voltage;

[0032] A controller, comprising at least one processor and a memory communicatively connected to the at least one processor, the memory storing instructions executable by the at least one processor to enable the at least one processor to perform the method described above.

[0033] Thirdly, embodiments of this application provide a computer storage medium storing instructions or programs that, when executed by at least one processor, cause the at least one processor to perform any of the methods described above.

[0034] The beneficial effects of this application embodiment are as follows: Unlike existing technologies, this application embodiment provides an MPPT control method for a multi-stage DC-DC topology. Three duty cycles are calculated based on the bus voltage loop, the input current loop, and a preset first formula, respectively. The smallest of these three duty cycles is selected as the control duty cycle for the BOOST boost circuit. The control duty cycle for the BUCK buck circuit is calculated based on a preset second formula. Through this control strategy, when the solar panel's illumination is insufficient to maintain the bus voltage at the target bus voltage (i.e., the charging power of the downstream energy storage product exceeds the energy provided by the solar panel's illumination), the control duty cycle of the BOOST boost circuit switches to the duty cycle calculated based on the first formula, while the control duty cycle of the BUCK buck circuit is calculated based on the second formula. This allows the multi-stage DC-DC converter to enter an open-loop control mode, enabling the original voltage-power characteristics of the solar panel to be reproduced almost without distortion and proportionally at the output port. This provides accurate and traceable power for portable energy storage devices with built-in MPPT functionality. Voltage observation environment. The method in this application effectively solves the core problem of MPPT function inaccuracy under multi-level DC-DC architecture while realizing multi-voltage adaptation and flexible construction of energy ecosystem, ensuring the overall energy capture efficiency of the system under a wide range of illumination conditions. Attached Figure Description

[0035] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0036] Figure 1 This is a schematic diagram of the UP characteristic curve of the solar photovoltaic panel provided in the embodiments of this application;

[0037] Figure 2 This is a schematic diagram of a common topology for charging portable energy storage devices using photovoltaic panels, as provided in the embodiments of this application.

[0038] Figure 3 This is a schematic diagram of a photovoltaic panel charging a portable energy storage device via a multi-stage DC-DC topology, as provided in an embodiment of this application.

[0039] Figure 4 This is a flowchart of the MPPT control method for a multi-level DC-DC topology provided in the embodiments of this application;

[0040] Figure 5 This is a schematic diagram of the control loop structure of the multi-stage DC-DC converter provided in this application embodiment under photovoltaic charging conditions;

[0041] Figure 6 This is a detailed flowchart of the MPPT control method for a multi-level DC-DC topology provided in the embodiments of this application;

[0042] Figure 7 This is a schematic diagram of the hardware structure of the controller for the multi-stage DC-DC converter provided in the embodiments of this application. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0044] Furthermore, the technical features involved in the various embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0045] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0046] Please refer to Figure 1 , Figure 1 A schematic diagram of the UP characteristic curve of a solar photovoltaic panel is shown. Figure 1 As shown, under no-load conditions, the voltage of the photovoltaic panel is at the open-circuit voltage. The energy storage device begins charging, with power gradually increasing, current increasing, and voltage decreasing. Moreover, the rate of current increase during this phase is much greater than the rate of voltage decrease; therefore, the power is in a ramp-up phase. When the voltage decreases to... At this point, the current tends to level off and become constant. If the voltage continues to decrease, the power will also decrease accordingly. This power point is the maximum power point of the photovoltaic panel, and its corresponding voltage is... The corresponding current is Based on the UP characteristic curve of solar photovoltaic panels, the currently mainstream and commonly used MPPT algorithm is the perturbation observation method, which uses the input voltage as the input control quantity and the power change as the observation quantity.

[0047] Please refer to Figure 2 , Figure 2 This diagram illustrates a common topology for charging portable energy storage devices using photovoltaic panels. (Example:) Figure 2As shown, the photovoltaic panel is directly connected to a portable energy storage device with a built-in DC-DC converter. The built-in DC-DC converter converts the electrical energy output from the photovoltaic panel into suitable DC power to charge the battery. In some embodiments, the portable energy storage device has an MPPT function designed based on the voltage-power characteristic curve of the photovoltaic panel, which can accurately track the maximum power point.

[0048] Please refer to Figure 3 , Figure 3 This diagram illustrates how a photovoltaic panel charges a portable energy storage device via a multi-stage DC-DC topology. (For example...) Figure 3 As shown, the photovoltaic panel is connected to a portable energy storage device with its own DC-DC converter after passing through a multi-stage DC-DC converter.

[0049] For example, this multi-stage DC-DC converter includes a BOOST boost circuit and a BUCK buck circuit connected in sequence. The BOOST boost circuit, composed of an input inductor L1, a first switch Q1, and a second switch Q2, boosts the photovoltaic input voltage to the DC bus voltage. The BUCK buck circuit, composed of a third switch Q3, a fourth switch Q4, and an output inductor L2, bucks the DC bus voltage to an adjustable charging output voltage. The output of the BOOST boost circuit and the input of the BUCK buck circuit are both connected to the DC bus node, forming a two-stage series-connected, bus-shared non-isolated DC-DC converter structure. In this topology, photovoltaic power is ultimately converted into suitable DC power to charge the battery through three stages of DC-DC conversion. The charging output voltage can be set according to the input requirements of the connected portable energy storage device, enabling photovoltaic panels with different voltage specifications to charge portable energy storage devices with different input voltage ranges.

[0050] Please refer to Figure 4 , Figure 4 A flowchart of an MPPT control method for a multi-stage DC-DC topology is shown. This method can be executed by a controller of a multi-stage DC-DC converter. In one embodiment, the topology of the multi-stage DC-DC converter is as follows: Figure 3 As shown, its specific structure has been described in detail in the above embodiments, and will not be repeated here.

[0051] like Figure 4 As shown, the MPPT control method for this multi-stage DC-DC topology includes:

[0052] Step S401: Sample the DC bus voltage and photovoltaic input current.

[0053] Step S402: Calculate three duty cycles based on the bus voltage loop, the input current loop, and the preset first formula, and select the smallest of the three duty cycles as the control duty cycle of the BOOST boost circuit.

[0054] Step S403: Calculate the control duty cycle of the BUCK step-down circuit based on the preset second formula.

[0055] based on Figure 3 As can be seen from the topology of the multi-stage DC-DC converter, the multi-stage DC-DC converter includes a BOOST boost circuit and a BUCK buck circuit connected in sequence. The BOOST boost circuit is used to boost the photovoltaic input voltage to the DC bus voltage, and the BUCK buck circuit is used to buck the DC bus voltage to an adjustable charging output voltage.

[0056] According to the theory of BOOST circuits, under CCM (Continuous Conduction Mode), the ideal relationship for the duty cycle of the second switch Q2 is:

[0057]

[0058] Similarly, according to the BUCK circuit theory, the ideal relationship for the duty cycle of the third switch Q3 is:

[0059]

[0060] in, Photovoltaic input voltage, This is the DC bus voltage. This is the charging output voltage.

[0061] Based on this, the first formula is designed as follows:

[0062]

[0063] The second formula is designed as follows:

[0064]

[0065] in, This is the voltage at the maximum power point of the photovoltaic panel. For the target bus voltage, The output voltage is used to charge the target.

[0066] Please refer to Figure 5 , Figure 5 A schematic diagram of the control loop structure of a multi-stage DC-DC converter under photovoltaic charging conditions is shown. Figure 5 As shown, the control loop includes a BOOST control loop from the photovoltaic input voltage to the DC bus voltage and a BUCK control loop from the DC bus voltage to the charging output voltage. Specifically, based on the DC bus voltage... and target bus voltage The first duty cycle, duty1, is obtained by performing PI (Proportional-Integral) control through the bus voltage loop, based on the photovoltaic input current. and preset input current threshold The second duty cycle, duty2, is obtained by PI control through the input current loop, based on the maximum power point voltage of the photovoltaic panel. and target bus voltage The third duty cycle, duty3, is calculated using the first formula mentioned above. This is based on the target charging output voltage. With the target bus voltage The fourth duty cycle, duty4, is calculated using the second formula mentioned above. The control duty cycle of the BOOST boost circuit is the minimum value among duty1, duty2, and duty3. The control duty cycle of the BUCK control loop is duty4.

[0067] Please refer to Figure 6 , Figure 6 A detailed flowchart illustrating the MPPT control method for a multi-stage DC-DC topology is shown. Figure 6 As shown, the MPPT control method for multi-level DC-DC topologies includes:

[0068] Step S601: Determine whether the multi-stage DC-DC converter is connected to photovoltaics. If yes, proceed to step S602. If no, turn off the switching transistor drive of the multi-stage DC-DC converter.

[0069] In one embodiment, the photovoltaic input voltage is sampled, and if the photovoltaic input voltage is greater than the photovoltaic online voltage threshold, it is determined that the multi-stage DC-DC converter is connected to the photovoltaic system.

[0070] Step S602: Obtain the open-circuit voltage of the photovoltaic panel, and determine the maximum power point voltage of the photovoltaic panel based on the open-circuit voltage.

[0071] The open-circuit voltage is the steady-state voltage when the photovoltaic system is first connected and under load. According to... Figure 1 The voltage-power characteristic curve of the photovoltaic panel shows that the maximum power point voltage of the photovoltaic panel is less than the open circuit voltage, and is located at about 0.8 times the open circuit voltage. Therefore, the maximum power point voltage of the photovoltaic panel can be set to about 0.8 times the open circuit voltage.

[0072] Step S603: Obtain the target charging output voltage set by the user, and determine the target bus voltage based on the target charging output voltage.

[0073] The DC bus voltage is stepped down by the BUCK step-down circuit to output the charging output voltage. Therefore, the target bus voltage must be greater than the target charging output voltage. For example, the target bus voltage can be set to the target charging output voltage plus a preset value.

[0074] Step S604: Calculate three duty cycles based on the bus voltage loop, the input current loop, and the preset first formula, and select the smallest of the three duty cycles as the control duty cycle of the BOOST boost circuit.

[0075] Specifically, the DC bus voltage and photovoltaic input current are sampled. Based on the DC bus voltage and the target bus voltage, PI (Proportional-Integral) control is performed through the bus voltage loop to obtain the first duty cycle. Based on the photovoltaic input current and a preset input current threshold, PI control is performed through the input current loop to obtain the second duty cycle. Based on the photovoltaic panel's maximum power point voltage and the target bus voltage, the third duty cycle is calculated using the aforementioned first formula. Here, the input current threshold is the maximum photovoltaic input current of the photovoltaic panel.

[0076] Step S605: Calculate the control duty cycle of the BUCK step-down circuit based on the second formula.

[0077] Specifically, the ratio of the target charging output voltage to the target bus voltage is calculated and used as the control duty cycle of the BUCK step-down circuit.

[0078] In this embodiment of the application, the working process is as follows: at the initial stage of photovoltaic access, the first-stage BOOST first boosts the voltage to the target bus voltage (at this time, the subsequent stage has not yet been turned on, there is no power output, the energy required to maintain the bus is very small, and the duty cycle is usually very small); after the bus stabilizes, the second-stage BUCK steps down the voltage to the set voltage (charging output voltage) to the output port and provides it to the subsequent stage.

[0079] When there is sufficient sunlight, the photovoltaic input power is much greater than the power demand of the downstream load (such as the charging power of portable energy storage devices). Its output energy can support the bus voltage to be maintained at the preset target bus voltage state. During this stage, the voltage loop dynamically adjusts to maintain voltage stability. The reason is that the fixed duty cycle calculated by the first formula is based on the duty cycle calculated according to the voltage theory corresponding to the maximum power point of PV. This operating condition will not reach the maximum power of PV, that is, the duty cycle (duty1) calculated by the voltage loop will be less than the fixed duty cycle.

[0080] When sunlight is insufficient, the maximum energy that the photovoltaic panel can provide (photovoltaic input power) is less than the power required by the downstream load (such as the charging power of portable energy storage devices). As the charging power gradually increases from zero, the duty cycle (duty1) calculated by the voltage loop PI regulation dynamically increases to maintain voltage stability. When the maximum power of the photovoltaic panel is exceeded, the bus voltage cannot be maintained, and the bus voltage loop will continue to increase until it reaches full-scale saturation, exceeding the duty cycle calculated based on the first formula. Therefore, in this stage, the duty cycle (duty3) calculated by the first formula takes over the BOOST control loop and enters the open-loop control mode.

[0081] In most stages, the current is generally less than the set maximum current, so the current loop is in integral saturation and full-bias state and does not participate in loop control. Only when the power rating of the photovoltaic panels used by the user exceeds the system's set maximum power current, and the sunlight is strong enough for the photovoltaic panels to output their nominal maximum power, and the charging power of the downstream energy storage products also exceeds the system's set maximum power, does the current exceed the given value. In this case, the duty cycle of the current loop's PI calculation gradually decreases, eventually intervening in the loop control to reduce the duty cycle and prevent overcurrent.

[0082] In this embodiment, when the photovoltaic output energy cannot support the bus voltage to remain at the target bus voltage, both the BOOST boost circuit and the BUCK buck circuit operate with a fixed duty cycle. The overall system gain is approximately constant, and the voltage-power characteristics of the photovoltaic panel are presented proportionally at the charging output port after transformation. In this case, the portable energy storage device detects the voltage and power changes at its input terminal and adjusts its equivalent load based on its built-in MPPT algorithm (such as the perturbation observation method) to track the maximum power point. The method of this application effectively solves the core problem of MPPT function inaccuracy under multi-level DC-DC architecture while achieving multi-voltage adaptation and flexible construction of energy ecosystem, ensuring the overall energy capture efficiency of the system under a wide range of illumination conditions.

[0083] Please refer to Figure 7 , Figure 7 This illustrates the hardware structure of the controller for a DC-DC converter. For example... Figure 7 As shown, the controller 70 includes at least one processor 71 and a memory 72. The memory 72 can be built into the controller 70 or external to the controller 70. The memory 72 can also be a remotely configured memory connected to the controller 70 via a network.

[0084] Memory 72, as a non-volatile computer-readable storage medium, can be used to store non-volatile software programs, non-volatile computer-executable programs, and modules. Memory 72 may include a program storage area and a data storage area, wherein the program storage area may store the 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. Furthermore, memory 72 may include high-speed random access memory and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other non-volatile solid-state storage device. In some embodiments, memory 72 may optionally include memory remotely located relative to processor 71, and these remote memories can be connected to the terminal via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0085] The processor 71 performs various functions of the terminal and processes data by running or executing software programs and / or modules stored in the memory 72 and calling data stored in the memory 72, thereby performing overall monitoring of the terminal, such as implementing the MPPT control method of the multi-level DC-DC topology described in any embodiment of this application.

[0086] There can be one or more processors 71. Figure 7 The example provided uses a processor 71. The processor 71 and memory 72 can be connected via a bus or other means. The processor 71 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 71 can 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.

[0087] This application also provides a computer storage medium storing instructions or programs that are executed by one or more processors, enabling the one or more processors to perform the MPPT control method for a multi-level DC-DC topology in any of the above method embodiments.

[0088] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a general-purpose hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the related technology, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., including several instructions to enable a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments.

[0089] The above description is merely a specific embodiment 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 variations or substitutions within the technical scope disclosed in this application. Therefore, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. An MPPT control method for a multi-stage DC-DC topology, characterized in that, An application is made in a multi-stage DC-DC converter, the multi-stage DC-DC converter including a BOOST boost circuit and a BUCK buck circuit connected in sequence, the BOOST boost circuit being used to boost the photovoltaic input voltage to the DC bus voltage, and the BUCK buck circuit being used to buck the DC bus voltage to the charging output voltage, the method comprising: Sample DC bus voltage and photovoltaic input current; Obtain the target charging output voltage set by the user, and determine the target bus voltage based on the target charging output voltage; Three duty cycles are calculated based on the bus voltage loop, the input current loop, and a preset first formula, respectively, and the smallest of the three duty cycles is selected as the control duty cycle of the BOOST boost circuit. The control duty cycle of the BUCK buck circuit is calculated based on the preset second formula. The calculation of the three duty cycles based on the bus voltage loop, the input current loop, and the preset first formula includes: Based on the DC bus voltage and the target bus voltage, a first duty cycle is obtained by performing PI control through the bus voltage loop. Based on the photovoltaic input current and the preset input current threshold, PI control is performed through the input current loop to obtain the second duty cycle; The third duty cycle is calculated using the first formula based on the maximum power point voltage of the photovoltaic panel and the target bus voltage. The first formula is: The second formula is: in, This is the voltage at the maximum power point of the photovoltaic panel. For the target bus voltage, The output voltage is used to charge the target.

2. The method according to claim 1, characterized in that, Before calculating the three duty cycles based on the bus voltage loop, the input current loop, and the preset first formula, the following is also included: Obtain the open-circuit voltage of the photovoltaic panel; The maximum power point voltage of the photovoltaic panel is determined based on the open-circuit voltage.

3. The method according to claim 2, characterized in that, The input current threshold is the maximum photovoltaic input current of the photovoltaic panel.

4. The method according to claim 2, characterized in that, The calculation of the control duty cycle of the BUCK buck circuit based on the preset second formula includes: Based on the target bus voltage and the target charging output voltage, the control duty cycle of the BUCK step-down circuit is calculated using a preset second formula.

5. The method according to claim 1, characterized in that, The output of the BUCK step-down circuit is connected to a portable energy storage device, which has MPPT control function.

6. A multi-stage DC-DC converter, characterized in that, include: The BOOST boost circuit is used to boost the photovoltaic input voltage to the DC bus voltage; The BUCK step-down circuit is used to step down the DC bus voltage to the charging output voltage; A controller, the controller including at least one processor and a memory communicatively connected to the at least one processor, the memory storing instructions executable by the at least one processor to enable the at least one processor to perform the method as described in any one of claims 1 to 5.

7. A computer storage medium, characterized in that, The computer storage medium stores instructions or programs that, when executed by at least one processor, cause the at least one processor to perform the method as described in any one of claims 1 to 5.

Images