An adaptive constant current control method and system for a DC-DC converter power supply

Abstract

The application relates to the technical field of power supply circuits, and particularly discloses a self-adaptive constant-current control method and system for a DC-DC direct-current conversion power supply, wherein the output voltage is acquired in real time and compared with a plurality of preset voltage thresholds, the interval where the output voltage is located is identified, the input current constant-current given value is reduced according to a first step value in response to the output voltage rising in the voltage limiting zone, the input current constant-current given value is reduced according to a second step value in response to the output voltage rising in the current sharing zone, and the first step value is greater than the second step value, so that the voltage overshoot caused by load shedding is quickly inhibited, the stable control of the output voltage is brought, the dynamic response capability of the system is improved, and the risk of damage of power devices due to overvoltage is reduced.

Description

Technical Field

[0001] This invention relates to the field of power supply circuit technology, and in particular to an adaptive constant current control method and system for DC-DC converter power supplies. Background Technology

[0002] In fuel cell or lithium battery power systems, when a DC-DC converter experiences a sudden change in output power (such as grid-connected to off-grid switching or load shedding), the output voltage is prone to overshoot, which may damage circuit components. Simultaneously, when multiple battery cells operate in parallel, there is an issue of uneven output current, affecting the battery pack's lifespan and system stability. Existing solutions relying on a main controller for regulation are slow to respond and increase system design costs. Summary of the Invention

[0003] To overcome the problems in existing fuel cell or lithium battery power supply systems, such as output voltage overshoot and uneven output current when output power changes abruptly, which affect the working life of the battery pack and system stability, this invention provides an adaptive constant current control method and system for DC-DC converter power supplies.

[0004] In a first aspect, the present invention provides an adaptive constant current control method for a DC-DC converter power supply, the method comprising:

[0005] Obtain the output voltage of the DC-DC converter; The output voltage is compared with the preset grid-connected voltage value, output voltage limit value, and off-grid voltage value; Based on the comparison results, adjust the constant current setpoint of the input current of the DC-DC converter; When the output voltage is greater than the output voltage limit value and less than the off-grid voltage value, it enters the voltage limiting region. In response to the rise in the output voltage, the constant current setpoint of the input current is reduced according to the first step value. When the output voltage is greater than or equal to the off-grid voltage value, the current sharing region is entered. In response to the rise in the output voltage, the constant current setpoint of the input current is reduced according to the second step value. Furthermore, the first step value is greater than the second step value.

[0006] According to one specific implementation, the calculation method for the first step value in the above control method is as follows: Determine the maximum setpoint of the input current and the maximum input current in the current sharing region; The first step value is calculated using the following formula: , in, This is the off-grid voltage value. This is the output voltage limit value. The maximum given value of the input current. This represents the maximum input current in the current sharing region. This is the first step value.

[0007] According to a specific implementation, in the above control method, the off-grid voltage value is calculated based on the product of the maximum output voltage limit, the second step value, and the maximum input current in the current sharing region. The calculation formula is as follows: , in, This is the maximum limit value for the output voltage. This is the second step value.

[0008] According to one specific implementation, in the above control method, the maximum input current in the current sharing region is calculated based on the required current sharing power, the number of parallel DC-DC converters, and the battery output voltage: , in, For the required current sharing power, The number of parallel DC-DC converters, This is the output voltage of the battery.

[0009] According to one specific implementation, in the above control method, the output voltage limit value is obtained by superimposing a buffer threshold on the grid-connected voltage value.

[0010] According to a specific implementation, in the above control method, when the output voltage is less than or equal to the grid-connected voltage value, or when the output voltage is greater than the grid-connected voltage value and less than or equal to the output voltage limit value, the DC-DC converter is controlled to operate at a constant current according to the current input current given value.

[0011] According to a specific implementation, in the above control method, when multiple DC-DC converters are running in parallel, within the current sharing region, the input current constant current setpoint of each DC-DC converter is synchronously reduced according to the same second step value to achieve automatic current sharing.

[0012] In a second aspect, the present invention provides a DC-DC converter, including a controller, the controller being configured to execute an adaptive constant current control method for a DC-DC converter power supply as described in any of the preceding claims.

[0013] Thirdly, the present invention provides a DC-DC converter power supply system, including a plurality of DC-DC converters as described above, wherein the input terminals of the plurality of DC-DC converters are connected to a battery array and the output terminals are connected to a load or a power grid.

[0014] According to one specific implementation, in the above power supply system, when the output voltage is in the current sharing region, each parallel DC-DC converter synchronously reduces its own input current constant current setpoint according to the second step value to achieve automatic current sharing.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention identifies the voltage range of an output voltage by acquiring the output voltage in real time and comparing it with multiple preset voltage thresholds. Within the voltage-limiting region, the input current constant current setpoint is reduced by a first step value in response to an increase in output voltage. Within the current-sharing region, the input current constant current setpoint is reduced by a second step value in response to an increase in output voltage, with the first step value being greater than the second step value. This achieves rapid suppression of voltage overshoot caused by load shedding, resulting in stable output voltage control, improved system dynamic response, and reduced risk of power device damage due to overvoltage. Simultaneously, by linearly reducing the input current of the DC-DC converter in small steps within the current-sharing region, the impact of drastic changes in battery output current on the battery is avoided, which helps maintain the optimal operating temperature of the fuel cell and extends battery life. Furthermore, in parallel operation scenarios, each converter synchronously reduces current according to the same second step value, achieving automatic current sharing without main controller intervention. This reduces system design costs and communication latency, and improves the reliability and balance of multi-module parallel operation. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a battery power generation system provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a solid oxide fuel cell power generation system provided in an embodiment of the present invention; Figure 3 A flowchart illustrating an adaptive constant current control method for a DC-DC converter power supply provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the adjustment strategy provided in an embodiment of the present invention. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0018] Unless otherwise specified, in the description of specific embodiments of the present invention, the terms "first," "second," "third," etc., are used merely to distinguish descriptions of identical or similar components and should not be construed as emphasizing or implying the relative importance of specific components. Furthermore, in the description of embodiments of the present invention, "several," "multiple," or "several" represent at least two. The number can be any number, such as 2, 3, 4, 5, 6, 7, 8, or 9, and may even exceed nine. Moreover, in the description of the technical solutions of the present invention, unless otherwise explicitly defined and limited, the terms "set," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to common connection methods in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication of two components.

[0019] In the description of this invention, a DC-DC converter refers to a power electronic device that boosts or bucks the DC voltage output from a battery (such as a fuel cell or lithium battery) to provide stable DC power to a load or power grid. The constant current setpoint refers to the target input current value set by the DC-DC converter controller. The controller adjusts the duty cycle of the switching transistors to make the actual input current track this setpoint. The voltage limiting region refers to the area where the output voltage exceeds the normal allowable range but has not yet reached the off-grid voltage. Within this region, the input current needs to be rapidly reduced to suppress voltage overshoot. The current sharing region refers to the area where the output voltage further increases to above the off-grid voltage. Within this region, the input current needs to be reduced in gradual steps, while simultaneously reducing the input current of each parallel converter synchronously to achieve automatic current sharing.

[0020] like Figure 1 As shown, in the field of fuel cells or lithium batteries, the battery outputs power to a DC-DC converter, which boosts the voltage and then outputs AC power to the load via a DC-AC module. During operation, the load may experience power decay, load shedding, and in extreme cases, no-load conditions. This can cause overshoot in the output voltage of the DC-DC converter. Furthermore, in practical applications, it is generally desirable to balance the output current of each battery cell group, and under extremely light loads, it is expected that each fuel cell group will have current output to maintain the fuel cell within its optimal operating temperature range and extend its service life. Existing technologies suffer from current sharing issues in these situations.

[0021] This invention is applicable to scenarios requiring multiple battery units to operate in parallel, such as fuel cell power generation systems and lithium battery energy storage systems. Taking a solid oxide fuel cell (SOFC) power generation system as an example, such as... Figure 2 As shown, multiple fuel cell units are connected to their respective DC-DC converters, and the outputs of each DC-DC converter are connected in parallel to the energy storage converter to supply power to AC loads or to the power grid.

[0022] In SOFC converter equipment, the DC-DC converter's role is to boost and stabilize the fuel cell's output voltage to the target input voltage of the energy storage converter. DC-DC converters typically employ an interleaved parallel boost topology, and the control structure often uses a dual-loop structure with an inner current loop and an outer voltage loop. SOFC converter equipment has two operating states: grid-connected operation and off-grid operation. Grid-connected operation converts the fuel cell's electrical energy into AC power for grid connection, while off-grid operation converts the fuel cell's electrical energy into AC power to supply the load. Grid-connected operation typically has higher power outputs, exceeding hundreds of kilowatts, while off-grid operation power is determined by the AC load, commonly ranging from several kilowatts to tens of kilowatts. When the SOFC converter switches from grid-connected to off-grid, the output power drops abruptly from hundreds of kilowatts to a few kilowatts. During this switching instant, the large power load shedding severely tests the DC-DC converter's regulation capability. If the DC-DC converter's regulation capability is poor, the output voltage of the DC-DC converter will surge sharply during the switching instant, even exceeding the voltage stress of critical components, leading to damage. SOFC converter equipment achieves power targets of hundreds of kilowatts by paralleling DC-DC converters, theoretically possessing unlimited expansion potential. However, the operating environment of fuel cell arrays is complex; product water and waste heat from the reaction can affect the dynamic performance of the fuel cell stack. To extend the service life of each individual fuel cell, a control system is needed to monitor and maintain the fuel cell stack in optimal operating condition. In practical applications, it is generally desirable to balance the output current of each fuel cell unit, and under extremely light loads, it is expected that each fuel cell unit will have current output to maintain the fuel cells within their optimal operating temperature range and extend their service life.

[0023] Existing technologies often employ a main controller to regulate the switching duty cycle of DC-DC converters and energy storage converters. This approach has several drawbacks in practical applications. For example, during system operation, the main controller needs to sample various parameters, calculate the duty cycle data, and then distribute it to each DC-DC converter and energy storage converter. Furthermore, this control scheme has a slow response to the load, and there is a risk of overvoltage at the DC-DC converter output during grid-connected / off-grid switching. In addition, the presence of a main controller increases the design cost of SOFC converter equipment.

[0024] Based on this, the adaptive constant current control method proposed in this embodiment of the invention can be autonomously responded to by the controller of each DC-DC converter. Each DC-DC converter adjusts the constant current setpoint of the input current according to the real-time output voltage value. Even when operating off-grid, it can ensure that each DC-DC converter operates with current sharing and quickly suppress voltage overshoot.

[0025] The control method provided in the embodiments of the present invention will be described and explained in detail below with reference to specific implementation methods.

[0026] For example, please refer to a single DC-DC converter. Figure 3 The diagram illustrates a flowchart of an adaptive constant current control method for a DC-DC converter provided by an embodiment of the present invention. The method includes: Step 1: Obtain the output voltage of the DC-DC converter.

[0027] For example, the controller of the DC-DC converter acquires the DC voltage signal at the converter output in real time through a voltage sampling circuit. This voltage sampling circuit may include a resistor divider network, an isolation amplifier, and an analog-to-digital converter (ADC). The controller (e.g., a digital signal processor (DSP) or microcontroller (MCU) reads the ADC conversion result at a fixed sampling period (e.g., once every 100 microseconds) to obtain the instantaneous value of the output voltage, denoted as . .

[0028] Step 2: Compare the output voltage with the preset grid-connected voltage value, output voltage limit value, and off-grid voltage value.

[0029] In one possible implementation, three voltage thresholds are pre-stored in the controller's internal memory: grid-connected voltage value Output voltage limit value and off-grid voltage value The grid-connected voltage value is the target DC bus voltage value controlled by the DC-AC inverter, for example, a bus voltage of 400V during grid-connected operation. The output voltage limit value is obtained by adding a buffer threshold to the grid-connected voltage value; for example, if the buffer threshold is set to 2V, then... Off-grid voltage value It is the threshold value for triggering current sharing protection, and its value is greater than The controller will collect the output voltage in real time. Compare with these three thresholds in turn to determine The interval in which it is located.

[0030] Step 3: Based on the comparison results, adjust the constant current setpoint of the input current of the DC-DC converter.

[0031] Specifically, the controller according to Different constant current setpoint adjustment strategies are implemented for different voltage ranges. Please refer to [reference needed]. Figure 4 This diagram illustrates the adjustment strategy provided in an embodiment of the present invention.

[0032] when Greater than and less than When the voltage limit is reached (i.e., entering the voltage limiting region), the controller recognizes that the system is in the voltage limiting region state. At this time, the controller responds to the rising trend of the output voltage and proceeds according to the first step value (denoted as...). β (to reduce the constant current setpoint of the input current in large steps).

[0033] For example, the controller internally maintains a constant current setpoint for the current input current. Within the voltage-limiting region, the controller records the output voltage in each sampling cycle. The current value is subtracted from the historical value stored in the previous cycle to obtain the voltage change. .like If the value is positive (i.e., the voltage is rising), then update according to the following formula. :

[0034] in, This is a preset or calculated large step value, typically in A / V. In this way, the faster the output voltage rises, the faster the input current setpoint falls, thus rapidly reducing input power and suppressing further increases in output voltage. If If the value is zero or negative (the voltage no longer increases), then no adjustment is needed for the time being. Alternatively, other strategies may be employed, but this embodiment primarily uses voltage rise as the triggering scenario.

[0035] when Greater than or equal to When the current sharing region is reached (i.e., entering the current sharing region), the controller recognizes that the system is in the current sharing region state. At this time, the controller responds to the rise in output voltage and adjusts the output voltage according to the second step value (denoted as...). (This is a small step) to reduce the constant current setpoint of the input current.

[0036] For example, within the current sharing region, the controller also detects the output voltage change in each sampling period. ,when When it is positive, according to Update the constant current setpoint. Because... Less than The rate of current decrease slows significantly, allowing the input current to decrease linearly and slowly. This is done to avoid thermal shock to the fuel cell caused by sudden changes in input current under light or no-load conditions, thus achieving automatic current sharing.

[0037] It is worth noting that the first step is the value. Greater than the second step value The large step size in the voltage limiting region is used to quickly suppress voltage spikes caused by load shedding and protect power devices; the small step size in the current sharing region is used to maintain current output in each battery cell when the power output is low, so as to maintain the optimal operating temperature of the fuel cell and extend its life, while achieving current balance among multiple modules.

[0038] Specifically, in one possible implementation, the first step value It is not a fixed constant, but rather calculated based on system design parameters. The controller first determines the output voltage limit, the maximum input current setpoint, and the maximum input current in the current sharing region. Then, it calculates using the following formula. :

[0039] in, This is the output voltage limit value. Set the maximum allowable input current value for the DC-DC converter (e.g., 1.2 times the rated input current). The input current value corresponding to the starting point of the current sharing region (i.e., when the output voltage reaches) At that time, the input current setpoint should be reduced to (Through the first step value) This ensures a sufficiently steep current drop slope within the voltage limiting region to quickly respond to voltage overshoot.

[0040] Furthermore, the off-grid voltage value This is the boundary between the voltage limiting region and the current sharing region. For example, the controller calculates this based on the product of the maximum output voltage limit, the second step value, and the maximum input current in the current sharing region:

[0041] in, This is the maximum allowable output voltage of the system (i.e., the overvoltage protection threshold). This is the preset second step value (small step). This is the maximum input current in the current-sharing region (i.e., the initial current value when entering the current-sharing region). This formula ensures that when the output voltage reaches... At that time, the input current setpoint just drops to zero. This is achieved by setting... and It can be calculated The location of the pressure limiting zone and the flow equalization zone is thus smoothly connected.

[0042] In one possible implementation, the second step value can be set to 0.1A / 0.1V, and the specific value can be adjusted according to the actual power supply design parameters.

[0043] In this embodiment of the invention, the first step value is used to quickly suppress output voltage overshoot when the load is shed, and the second step value is used to linearly reduce the input current to maintain the battery operating temperature when under light load or no load.

[0044] Furthermore, the maximum input current in the current sharing region The calculation is based on the required current sharing power, the number of parallel DC-DC converters, and the battery output voltage. For example, the controller or host computer calculates using the following formula: :

[0045] in, This refers to the total output power that the system needs to maintain in the current sharing region (i.e., the power level under light load). The number of DC-DC converters operating in parallel. Let V be the output voltage of the battery cell (assuming all battery voltages are essentially the same). This formula ensures that within the current-sharing region, each converter shares the same input current, thus achieving balanced output power across all battery cells. For example, if the system needs to maintain a current-sharing power of 1kW, with 4 cells connected in parallel and a battery output voltage of 50V, then... .

[0046] Furthermore, the output voltage limit is obtained by adding a buffer threshold to the grid-connected voltage. The buffer threshold is introduced to prevent the output voltage from slightly exceeding the grid-connected voltage and mistakenly entering the voltage limiting region during grid-connected operation due to detection errors or minor disturbances. In this embodiment, the buffer threshold is set to 2V. This value can be adjusted according to the actual power supply design parameters.

[0047] Furthermore, when the output voltage Less than or equal to the grid-connected voltage value At that time, or when Greater than the grid-connected voltage value However, when the output voltage is less than or equal to the limit value, the controller does not perform current reduction operation, but instead controls the DC-DC converter to operate at a constant current according to the current input current setpoint. Specifically, in the grid-connected area ( ≤ Within the buffer, the controller maintains the user-defined or system default input current setpoint (e.g., rated current). < ≤ Within this range, although the voltage rises slightly, it remains within the allowable fluctuation range. The controller keeps the current setpoint constant to avoid unnecessary power surges caused by minor fluctuations, thereby ensuring stable grid-connected output.

[0048] In this invention, by setting a reasonable off-grid voltage value, the overshoot of the output voltage can be quickly suppressed in the voltage-limiting region during grid-to-off switching or load shedding. In the current-sharing region, a small step can be used to suppress the output voltage overshoot and achieve current sharing among each DC-DC module. If the off-grid voltage value is not set reasonably, it will have varying degrees of impact on the control system. When the set off-grid voltage value is greater than the reasonable value, uneven current distribution may occur among the DC-DC converters during off-grid operation, and the current deviation between the DC-DC converters may be too large. When the set off-grid voltage value is less than the reasonable value, the step value in the voltage-limiting region will be increased. For fuel cells, frequent and large-scale changes in output current will affect their service life. Therefore, the given step of the input current needs to be as small as possible to make the input current change approximately linear, thus protecting the fuel cell for long-term operation.

[0049] Based on the above technical solution, this embodiment of the invention identifies the range of the output voltage by acquiring the output voltage in real time and comparing it with multiple preset voltage thresholds. Within the voltage limiting region, the input current constant current setpoint is reduced by a first step value in response to an increase in output voltage. Within the current sharing region, the input current constant current setpoint is reduced by a second step value in response to an increase in output voltage, with the first step value being greater than the second step value. This achieves rapid suppression of voltage overshoot caused by load shedding, resulting in stable output voltage control, improved system dynamic response capability, and reduced risk of power device damage due to overvoltage. Simultaneously, by linearly reducing the input current of the DC-DC converter in small steps within the current sharing region, the impact of drastic changes in battery output current on the battery is avoided, which helps maintain the optimal operating temperature of the fuel cell and extends battery life. Furthermore, in parallel operation scenarios, each converter synchronously reduces current according to the same second step value, achieving automatic current sharing without the need for main controller intervention. This reduces system design costs and communication latency, and improves the reliability and balance of multi-module parallel operation.

[0050] On the other hand, embodiments of the present invention also provide a DC-DC converter, which includes a controller. The controller may be a digital signal processor (DSP), a microcontroller (MCU), a field-programmable gate array (FPGA), or a dedicated power management integrated circuit. The controller has an internal or external memory that stores computer program instructions. When the processor executes these instructions, it can implement the aforementioned adaptive constant current control method for a DC-DC power supply. The main circuit of the converter may adopt an interleaved parallel BOOST topology or other suitable DC-DC topology, including components such as power switches, inductors, and capacitors. The controller is connected to the gate of the power switch through a drive circuit and outputs a PWM signal to control the switching on and off of the power switch.

[0051] On the other hand, embodiments of the present invention also provide a DC-DC converter power supply system, which includes multiple DC-DC converters as described above. The input terminals of the multiple converters are connected to a battery array (e.g., multiple fuel cell stacks or lithium battery packs), and the output terminals are connected to a common DC bus. The DC bus is then connected to an AC load or the power grid via a DC-AC inverter. When the system output voltage is in the current-sharing region (i.e....), ≥ Each parallel DC-DC converter operates according to the same second step value. The system simultaneously reduces the constant current setpoint of each input current, thereby achieving automatic current sharing. The entire system requires no central controller and boasts advantages such as simple structure, fast response speed, and high reliability.

[0052] It should be understood that the processor in the embodiments of the present invention can be an integrated circuit chip with signal processing capabilities. In implementation, each step of the above method embodiments can be completed by the integrated logic circuits in the processor's hardware or by instructions in software form. The processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of the present invention. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of the present invention can be directly embodied in the execution of a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software modules can be located in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory; the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above methods.

[0053] It should also be understood that the memory in the embodiments of the present invention can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct rambus RAM (DR RAM). It should be noted that the memory used in the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An adaptive constant current control method for a DC-DC converter power supply, characterized in that, The method includes: Obtain the output voltage of the DC-DC converter; The output voltage is compared with the preset grid-connected voltage value, output voltage limit value, and off-grid voltage value; Based on the comparison results, adjust the constant current setpoint of the input current of the DC-DC converter; When the output voltage is greater than the output voltage limit value and less than the off-grid voltage value, it enters the voltage limiting region. In response to the rise in the output voltage, the constant current setpoint of the input current is reduced according to the first step value. When the output voltage is greater than or equal to the off-grid voltage value, the current sharing region is entered. In response to the rise in the output voltage, the constant current setpoint of the input current is reduced according to the second step value. Furthermore, the first step value is greater than the second step value; Among them, the grid-connected voltage value is the target voltage value of the DC bus controlled by the DC-AC inverter, the output voltage limit value is obtained by superimposing a buffer threshold on the grid-connected voltage value, and the off-grid voltage value is the threshold value for triggering current sharing protection.

2. The adaptive constant current control method for a DC-DC converter power supply according to claim 1, characterized in that, The calculation method for the first step value is as follows: Determine the maximum setpoint of the input current and the maximum input current in the current sharing region; The first step value is calculated using the following formula: ， in, This is the off-grid voltage value. This is the output voltage limit value. The maximum given value of the input current. This represents the maximum input current in the current sharing region. This is the first step value.

3. The adaptive constant current control method for a DC-DC converter power supply according to claim 2, characterized in that, The off-grid voltage value is calculated based on the product of the maximum output voltage limit, the second step value, and the maximum input current in the current sharing region. The calculation formula is as follows: ， in, This is the maximum limit value for the output voltage. This is the second step value.

4. The adaptive constant current control method for a DC-DC converter power supply according to any one of claims 2 or 3, characterized in that, The maximum input current in the current sharing region is calculated based on the required current sharing power, the number of parallel DC-DC converters, and the battery output voltage: ， in, For the required current sharing power, The number of parallel DC-DC converters, This is the output voltage of the battery.

5. The adaptive constant current control method for a DC-DC converter power supply according to claim 3, characterized in that, When the output voltage is less than or equal to the grid-connected voltage value, or when the output voltage is greater than the grid-connected voltage value and less than or equal to the output voltage limit value, the DC-DC converter is controlled to operate at a constant current according to the current input current setpoint.

6. The adaptive constant current control method for a DC-DC converter power supply according to claim 1, characterized in that, When multiple DC-DC converters are operating in parallel, within the current sharing region, the input current constant current setpoint of each DC-DC converter is synchronously reduced according to the same second step value to achieve automatic current sharing.

7. A DC-DC converter, characterized in that, Includes a controller for executing an adaptive constant current control method for a DC-DC converter power supply according to any one of claims 1 to 6.

8. A DC-DC converter power supply system, characterized in that, It includes multiple DC-DC converters as described in claim 7, wherein the input terminals of the multiple DC-DC converters are connected to a battery array and the output terminals are connected to a load or a power grid.

9. The system according to claim 8, characterized in that, When the output voltage is in the current sharing region, each parallel DC-DC converter synchronously reduces its input current constant current setpoint according to the second step value to achieve automatic current sharing.

Images