Control method of converter, converter and energy storage system

Abstract

The invention relates to a converter control method, a converter and an energy storage system. The method comprises the following steps: in an off-grid mode and in a load starting process, setting a duty ratio of a switching tube in the converter according to a preset first reference voltage; wherein the duty ratio is related to the output voltage of the first end; detecting whether the current first effective current of the first end is greater than the rated current of the converter; if the first effective current is greater than the rated current, adjusting the duty ratio of the switching tube according to the second reference voltage so as to reduce the first effective current; wherein the second reference voltage is determined according to the first reference voltage, and the second reference voltage is smaller than the first reference voltage. By adopting the method, the stability and reliability of the converter can be improved in the load starting process.

Description

Technical Field

[0001] The present application relates to the technical field of energy storage and current conversion, and in particular to a control method for a converter, a converter, and an energy storage system. Background Art

[0002] The converter is the core control unit of the energy storage system, which can convert direct current (DC) to alternating current (AC). The converter generally has a grid-connected mode and / or an off-grid mode.

[0003] Taking a PCS (Power Conversion System) with both grid-connected and off-grid modes as an example, in grid-connected mode, the PCS can invert the DC power of the energy storage system into AC power for use in the power grid; it can also rectify the AC power of the grid into DC power and store it in the energy storage system. In off-grid mode, the PCS can invert the DC power of the energy storage system into AC power for use by AC loads.

[0004] However, in off-grid mode, converters often suffer from poor stability and reliability. Summary of the Invention

[0005] Based on this, it is necessary to provide a control method for a converter, a converter, and an energy storage system that can improve the stability and reliability of the converter during load startup in order to address the above technical problems.

[0006] In a first aspect, the present application provides a control method for a converter, which is applied to a converter, wherein a first end of the converter is connected to a load, and the converter is used to supply power to the load, and the method includes:

[0007] In off-grid mode and during load startup, setting a duty cycle of a switch in the converter according to a preset first reference voltage; wherein the duty cycle is related to the output voltage of the first end;

[0008] Detecting whether a first effective current currently at the first end is greater than a rated current of the converter;

[0009] If the first effective current is greater than the rated current, the duty cycle of the switch tube is adjusted according to the second reference voltage to reduce the first effective current; wherein the second reference voltage is determined according to the first reference voltage, and the second reference voltage is less than the first reference voltage.

[0010] In one embodiment, after adjusting the duty cycle of the switch tube according to the second reference voltage, the method further includes:

[0011] Detect whether the current working state meets the constant power control condition; the constant power control condition is used to indicate that the high current demand during the load startup process has ended;

[0012] If the constant power control condition is met, the third reference voltage is determined according to the preset constant power, and the duty cycle of the switching tube is adjusted according to the third reference voltage, wherein the preset constant power is related to the rated apparent power of the converter, the third reference voltage is greater than the second reference voltage, and the third reference voltage is less than or equal to the rated voltage of the converter.

[0013] In one embodiment, the operating state includes a first time interval, and detecting whether the current operating state satisfies the constant power control condition includes:

[0014] Determine a first time interval; wherein the first time interval is the time interval between the time when the duty cycle of the switch tube is adjusted according to the second reference voltage and the current time;

[0015] If the first time interval is greater than a preset first threshold, it is determined that the constant power control condition is met.

[0016] In one embodiment, the working state includes a second effective current currently at the first terminal, and detecting whether the current working state satisfies the constant power control condition includes:

[0017] Detecting whether the second effective current currently flowing through the first terminal is less than a preset current threshold value; wherein the current threshold value is equal to the product of the rated current and a preset coefficient, and the preset coefficient is equal to the ratio of the second reference voltage to the first reference voltage;

[0018] If the second effective current is less than the current threshold, it is determined that the constant power control condition is met.

[0019] In one embodiment, determining the third reference voltage according to the preset constant power includes:

[0020] determining a candidate reference voltage according to the preset constant power and a third effective current currently at the first end;

[0021] A minimum voltage among the candidate reference voltage and the rated voltage is determined as a third reference voltage.

[0022] In one embodiment, determining a candidate reference voltage according to a preset constant power and a third effective current currently at the first terminal includes:

[0023] The candidate reference voltage is obtained by dividing the preset constant power by the third effective current.

[0024] In one embodiment, when the candidate reference voltage is the minimum voltage, after adjusting the duty cycle of the switch according to the third reference voltage, the method further includes:

[0025] Determine a second time interval; wherein the second time interval is the time interval between the time when the duty cycle of the switch tube is adjusted according to the third reference voltage and the current time;

[0026] If the second time interval is greater than a preset second threshold, the duty cycle of the switch tube is adjusted according to the rated voltage.

[0027] In one embodiment, before adjusting the duty cycle of the switch tube according to the second reference voltage, the method further includes:

[0028] The first reference voltage is multiplied by a preset coefficient to obtain a second reference voltage, where the preset coefficient is greater than 0 and less than 1.

[0029] In a second aspect, the present application provides a converter, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the method described in the first aspect when executing the computer program.

[0030] In a third aspect, the present application provides an energy storage system, comprising an energy storage battery and the converter as described in the second aspect above, wherein the input end of the converter is connected to the energy storage battery, the first end of the converter is connected to the load, and the converter is used to supply power to the load.

[0031] In a fifth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described in the first aspect above.

[0032] In the control method, converter, and energy storage system of the converter, the first end of the converter is connected to the load, and the converter is used to supply power to the load. When the converter is in off-grid mode and the load is started, the converter sets the duty cycle of the switch tube in the converter according to a preset first reference voltage. The duty cycle is related to the output voltage of the first end of the converter. Since impact AC loads such as motors and high-power electrical appliances generate instantaneous high current demands during startup, this can adversely affect the stability and reliability of the converter. Therefore, the converter in the embodiment of the present application detects whether the current first effective current at the first end is greater than the rated current of the converter. If the first effective current is greater than the rated current, the converter adjusts the duty cycle of the switch tube according to a second reference voltage to reduce the first effective current. The second reference voltage is determined based on the first reference voltage and is less than the first reference voltage. This can reduce the impact of the instantaneous high current on the converter during load startup, thereby improving the stability and reliability of the converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments of the present application or related technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 A diagram showing an application environment of a method for controlling a converter according to an embodiment;

[0035] Figure 2 1 is a flow chart of a method for controlling a converter in one embodiment;

[0036] Figure 3 Schematic diagram of the internal structure of a unidirectional inverter in one embodiment;

[0037] Figure 4 is a flow chart of a method for controlling a converter in another embodiment;

[0038] Figure 5 is a structural block diagram of a control device for a converter in one embodiment;

[0039] Figure 6 FIG. 4 is a diagram showing the internal structure of a converter in one embodiment. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0041] The converter is the core control unit of the energy storage system, capable of converting DC to AC. Converters generally have grid-connected and / or off-grid modes. A PCS (Power Conversion System) with both grid-connected and off-grid modes can, in grid-connected mode, invert the DC power of the energy storage system into AC for use in the power grid, or rectify the AC power of the grid into DC for storage in the energy storage system. This means that by interacting with the grid, the PCS can feed power to or draw power from the grid, achieving bidirectional power flow. In off-grid mode, the PCS can invert the DC power of the energy storage system into AC for use by AC loads.

[0042] However, for inverters with off-grid mode, impact AC loads such as motors and high-power electrical appliances will generate instantaneous high current demands during startup. The required current is usually 3 to 5 times the rated current of the inverter, which will have an adverse effect on the stability and reliability of the inverter, resulting in poor stability and reliability of the inverter.

[0043] In the related art, a PCS with greater power is used to drive the load, for example, the ratio of the load power to the rated power of the PCS is set to 1:2. However, this method increases the cost of the converter.

[0044] In view of this, embodiments of the present application provide a control method for a converter, a converter, and an energy storage system, which can improve the stability and reliability of the converter during load startup and are beneficial to cost control of the converter.

[0045] The control method of the converter provided in the embodiment of the present application can be applied to Figure 1 In the implementation environment shown.

[0046] The energy storage system 100 includes a converter 102 . The converter 102 may be a PCS, a three-phase inverter, a unidirectional inverter, a split-phase inverter, etc. The converter 102 at least has an off-grid mode.

[0047] like Figure 1 As shown, a first end of the converter 102 is connected to the load 200 . The energy storage system 100 further includes an energy storage battery 104 . A second end of the converter 102 is connected to the energy storage battery 104 .

[0048] Optionally, the converter 102 may also have a grid-connected mode, and the first end of the converter 102 may also be connected to the grid ( Figure 1 There is no restriction on the types of working modes supported by the converter 102.

[0049] In an exemplary embodiment, Figure 2 As shown, a control method for a converter is provided, which is applied to Figure 1 The converter 102 in FIG. 1 is taken as an example for description. Exemplarily, the converter 102 includes a controller, and the control method of the converter is used in the controller.

[0050] The process includes the following steps 201 to 203:

[0051] Step 201 : In an off-grid mode and during load startup, setting a duty cycle of a switch in a converter according to a preset first reference voltage.

[0052] In off-grid mode, the converter converts the DC power of the energy storage battery in the energy storage system into AC power for the load, so that the load can be started and put into use.

[0053] The converter generally includes components such as switching tubes, capacitors, inductors, and controllers. The main function of the switching tube is to convert direct current into alternating current through rapid switching actions. The capacitors and inductors work together to ensure the circuit performance of the converter. The controller can control the duty cycle of the switching tube, etc.

[0054] Take the case where the converter is a unidirectional inverter as an example, see Figure 3 , Figure 3 is a schematic diagram of the internal structure of an exemplary unidirectional inverter (it should be noted that Figure 3 The controller in the unidirectional inverter is not shown). Figure 3 The BAT+ shown is connected to the positive electrode of the energy storage battery. Figure 3 The BAT- shown is connected to the negative pole of the energy storage battery, N is the neutral line (zero line) terminal, L1 and L2 are the AC output terminals of the unidirectional inverter, connected to the load.

[0055] During the process of converting the DC power of the energy storage battery into AC power, the converter (specifically, the controller in the converter) can use the first reference voltage as a voltage feedforward value (or voltage reference value) in a control loop to adjust the duty cycle of the switch tube in the converter, which is related to the output voltage at the first end.

[0056] Exemplarily, the converter sets the duty cycle of the switch tube in the converter according to the first reference voltage, so that the output voltage of the first end of the converter is equal to the first reference voltage.

[0057] In the embodiment of the present application, the first reference voltage may be equal to the rated voltage of the converter, which is the off-grid output rated AC voltage of the converter.

[0058] Step 202: Detect whether the current first effective current at the first terminal is greater than the rated current of the converter.

[0059] In the embodiment of the present application, when the load is an impact AC load such as an electric motor or a high-power electrical appliance, the load will generate an instantaneous high current demand at startup, which will adversely affect the stability and reliability of the converter. Therefore, the converter can detect whether the current first effective current at the first end of the converter is greater than the rated current of the converter.

[0060] Exemplarily, the converter may collect the real-time current of the first terminal of the converter, and calculate the current effective current of the first terminal based on the real-time current, that is, the first effective current in step 202 .

[0061] Continue with Figure 3Taking the unidirectional inverter shown as an example, the unidirectional inverter can sample the inductor current on L1 or L2, and calculate the first effective current based on the sampled inductor current.

[0062] In a possible implementation manner, the converter may further include a sensor for sampling the inductor current on L1 or L2. A detection circuit may be provided between the sensor and the controller to calculate the first effective current from the inductor current sampled by the sensor through this detection circuit, and detect whether the first effective current is greater than the rated current of the converter through this detection circuit. If the first effective current is greater than the rated current, the detection circuit outputs an overcurrent signal.

[0063] In this way, whether the controller in the converter itself detects whether the above first effective current is greater than the rated current of the converter or detects through the detection circuit, the converter can obtain the detection result.

[0064] Step 203, if the first effective current is greater than the rated current, adjust the duty cycle of the switching tube according to the second reference voltage to reduce the first effective current.

[0065] If the first effective current is greater than the rated current, it indicates that the converter is providing an instantaneous high current to the load. To reduce the impact of this instantaneous high current on the converter, the converter uses the second reference voltage as the voltage feedforward value in the control loop. The second reference voltage is determined according to the first reference voltage, and the second reference voltage is less than the first reference voltage. Adjust the duty cycle of the switching tube according to the second reference voltage so that the output voltage at the first end of the converter is equal to the second reference voltage, thereby reducing the first effective current, and the power of the converter also decreases accordingly.

[0066] Exemplarily, the converter can multiply the first reference voltage by a preset coefficient n1 to obtain the second reference voltage, that is, the second reference voltage = n1 * Un, where Un is the above-mentioned rated voltage, Un is equal to the first reference voltage, and the preset coefficient n1 can be set by itself during implementation. The preset coefficient is greater than 0 and less than 1, for example, 0.5 < n1 < 1, etc.

[0067] In the above embodiment, when the impactful AC load starts instantaneously, by reducing the voltage feedforward value in the control loop, the effective current at the first end of the converter is reduced, thereby reducing the impact of the instantaneous high current during load startup on the converter, and improving the stability and reliability of the converter.

[0068] In one embodiment, on the basis of Figure 2 the embodiment shown, referring to Figure 4 , after step 203, the control method of the converter in this embodiment may further include Figure 4 the steps 401 and 402 shown in

[0069] Step 401: Check whether the current working state meets the constant power control condition.

[0070] In an embodiment of the present application, the converter adjusts the duty cycle of the switching tube according to the second reference voltage, and after reducing the first effective current, it will enter a constant power control process when the constant power control condition is met. During the startup of the impact AC load, there will be a short period of high current demand (for example, between 0.5s-1.5s). The constant power control condition is used to characterize the end of the high current demand during the startup of the load. Through the constant power control process, the output voltage of the converter is limited, and it gradually switches from the second reference voltage to the rated voltage.

[0071] The converter first detects whether the current working state meets the constant power control condition.

[0072] In a possible implementation of step 401, the current working state of the converter includes a first time interval. The converter can determine the first time interval, which is the time interval between the time for adjusting the duty cycle of the switch tube according to the second reference voltage and the current time. The first time interval is the duration for maintaining the second reference voltage. The first threshold can be set by itself during implementation, such as being set to a time period with high current demand when an impact AC load starts, such as between 0.5s-1.5s, preferably 1s, and so on.

[0073] If the first time interval is greater than the preset first threshold, it indicates that the high current demand of the impact AC load at startup has ended, thereby determining that the constant power control condition is met.

[0074] In another possible implementation of step 401, the current working state of the converter includes the current second effective current of the first end of the converter. The converter can detect whether the current second effective current of the first end is less than a preset current threshold, which is equal to the product of the rated current of the converter and a preset coefficient, and the preset coefficient is equal to the ratio of the second reference voltage to the first reference voltage, that is, the preset coefficient is equal to the above-mentioned n1.

[0075] If the second effective current is less than the current threshold, it indicates that the first effective current has been successfully reduced (reduced to a smaller second effective current). Since the first effective current has been successfully reduced, it indicates that the high current demand of the inrush AC load at startup has ended, thereby determining that the constant power control condition is met.

[0076] In other possible embodiments of step 401, the converter may also combine the above two embodiments of step 401. Exemplarily, the converter continuously detects whether the second effective current is less than a preset current threshold within the above first time interval. Once it is detected that the second effective current is less than the current threshold, it is determined that the constant power control condition is satisfied; and if the duration of the second reference voltage has reached the first time interval and the second effective current has not been detected to be less than the current threshold, the converter also determines that the constant power control condition is satisfied.

[0077] Step 402, if the constant power control condition is satisfied, determine a third reference voltage according to a preset constant power, and adjust the duty cycle of the switching tube according to the third reference voltage.

[0078] Among them, the preset constant power is related to the rated apparent power of the converter. For example, the preset constant power = Sn * n2, where Sn is the rated apparent power of the converter, the coefficient n2 is greater than 1, and the coefficient n2 can be set by itself during implementation. For example, 1 < n2 < 1.3, and it can be determined in combination with the overload performance of the converter.

[0079] When the constant power control condition is satisfied, the converter first determines the third reference voltage according to the preset constant power, and then adjusts the duty cycle of the switching tube according to the third reference voltage. The third reference voltage is greater than the second reference voltage and less than or equal to the rated voltage of the converter.

[0080] Hereinafter, the process of the converter determining the third reference voltage according to the preset constant power will be introduced exemplarily.

[0081] Exemplarily, the converter can determine a candidate reference voltage according to the preset constant power and the current third effective current at the first end. For example, the candidate reference voltage is obtained by dividing the preset constant power by the third effective current. Then, the converter determines the minimum voltage between the candidate reference voltage and the rated voltage as the third reference voltage. That is, the converter performs a minimum operation between the candidate reference voltage and the rated voltage, and takes the smaller voltage as the third reference voltage.

[0082] Among them, the third effective current can be the effective current (i.e., the second effective current) at the first end calculated when detecting whether the constant power control condition is satisfied. Of course, it can also be the effective current at the first end calculated in real time when determining the third reference voltage according to the preset constant power.

[0083] It can be understood that since 1 < n2 < 1.3, the preset constant power is greater than the rated apparent power of the converter. When the third effective current (the reduced first effective current) is small, that is, the first effective current has been successfully reduced, then the candidate reference voltage obtained by dividing the preset constant power by the third effective current will be greater than the rated voltage of the converter. In this case, the duty cycle of the switching tube is adjusted according to the rated voltage to control the converter to operate at the rated voltage, limit the operating voltage of the converter, and avoid damaging the converter.

[0084] If the third effective current is large, that is, the reduction effect of the first effective current is not obvious, and the third effective current still has a certain impact on the converter, then the candidate reference voltage obtained by dividing the preset constant power by the third effective current may be less than the rated voltage of the converter. At this time, the candidate reference voltage is used to control the operation of the converter. By limiting the operating voltage of the converter, it is beneficial to reduce the third effective current and the impact current of the load.

[0085] Further, when the candidate reference voltage is the minimum voltage, after the converter adjusts the duty cycle of the switching tube according to the third reference voltage, the converter can also determine a second time interval, which is the time interval between the time when the duty cycle of the switching tube is adjusted according to the third reference voltage and the current time. If the second time interval is greater than the preset second threshold, the duty cycle of the switching tube is adjusted according to the rated voltage. The second time interval can be set by itself during implementation, for example, set between 0.5 s and 1.5 s, preferably 1 s, and so on.

[0086] The impact AC load has an instantaneous high current demand during startup. Therefore, this high current demand also impacts the converter instantaneously. After the impact ends, the converter needs to resume normal operation at the rated voltage to ensure the normal operation of the load.

[0087] In addition, in the embodiment of the present application, when the current operating voltage of the converter (the rated apparent power of the converter divided by the third effective current) is small, the operating voltage of the converter will not be directly raised to a large rated voltage. Instead, the candidate reference voltage (the preset constant power divided by the third effective current, and the preset constant power is n2 times the rated apparent power of the converter) is first used to control the operation of the converter. After operating for the second time interval, the converter is then controlled to operate according to the rated voltage of the converter, realizing a stepped increase in the operating voltage of the converter, and ensuring that the converter stably and reliably supplies power to the load in the off-grid mode.

[0088] In one embodiment, a control method for a converter is provided, which is applied to the converter and includes the following steps:

[0089] Step A1: In an off-grid mode and during load startup, setting a duty cycle of a switch in the converter according to a preset first reference voltage.

[0090] The duty cycle is related to the output voltage of the first end.

[0091] Step A2: Detect whether the current first effective current at the first end is greater than the rated current of the converter.

[0092] Step A3: If the first effective current is greater than the rated current, the duty cycle of the switch tube is adjusted according to the second reference voltage to reduce the first effective current.

[0093] The second reference voltage is lower than the first reference voltage, and the second reference voltage is obtained by multiplying the first reference voltage by a preset coefficient, where the preset coefficient is greater than 0 and less than 1.

[0094] Step A3: detecting whether the current working state satisfies a constant power control condition, where the constant power control condition is used to indicate that the high current demand during the load startup process has ended.

[0095] In a possible implementation of step A3, the working state includes a first time interval, and the converter determines the first time interval. If the first time interval is greater than a preset first threshold, it is determined that the constant power control condition is met, wherein the first time interval is the time interval between the time when the duty cycle of the switching tube is adjusted according to the second reference voltage and the current time.

[0096] In another possible implementation of step A3, the working state includes the current second effective current of the first end of the converter, and the converter detects whether the current second effective current of the first end is less than a preset current threshold. If the second effective current is less than the current threshold, it is determined that the constant power control condition is met, wherein the current threshold is equal to the product of the rated current and a preset coefficient, and the preset coefficient is equal to the ratio of the second reference voltage to the first reference voltage.

[0097] Step A4: if the constant power control condition is met, determining a candidate reference voltage according to the preset constant power and the third effective current currently at the first end.

[0098] The candidate reference voltage may be obtained by dividing the preset constant power by the third effective current, and the preset constant power is related to the rated apparent power of the converter.

[0099] Step A5: determining the minimum voltage between the candidate reference voltage and the rated voltage as the third reference voltage.

[0100] Step A6: adjusting the duty cycle of the switch tube according to the third reference voltage.

[0101] The third reference voltage is greater than the second reference voltage, and the third reference voltage is less than or equal to the rated voltage of the converter.

[0102] Step A7: when the candidate reference voltage is the minimum voltage, determine a second time interval.

[0103] The second time interval is the time interval between the time when the duty cycle of the switch tube is adjusted according to the third reference voltage and the current time.

[0104] Step A8: If the second time interval is greater than a preset second threshold, the duty cycle of the switch tube is adjusted according to the rated voltage.

[0105] In the embodiment of the present application, when configuring the rated power of the converter and the rated power of the load, there is no need to overmatch, and a 1:1 configuration is sufficient, which is beneficial to the cost control of the converter. In addition, in the embodiment of the present application, the control method of the converter is simple, has no impact on the dynamic response capability of the load, can improve the converter's adaptability to impact loads, and the output voltage waveform of the converter is not clipped or distorted, thereby improving the power quality.

[0106] It should be understood that, although the various steps in the flowcharts involved in the various embodiments described above are displayed in sequence according to the instructions of the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the flowcharts involved in the various embodiments described above can include multiple steps or multiple stages, and these steps or stages are not necessarily executed and completed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of steps or stages in other steps.

[0107] Based on the same inventive concept, embodiments of the present application further provide a converter control device for implementing the converter control method described above. The solution provided by this device is similar to the solution described in the method described above. Therefore, the specific limitations of the one or more converter control device embodiments provided below can be found in the limitations of the converter control method described above and are not further elaborated here.

[0108] In an exemplary embodiment, Figure 5 As shown, a control device for a converter is provided, which is applied to a converter, wherein a first end of the converter is connected to a load, and the converter is used to supply power to the load. The device includes:

[0109] A first control module 501 is configured to set a duty cycle of a switch in the converter according to a preset first reference voltage in an off-grid mode and during startup of the load; wherein the duty cycle is related to the output voltage of the first terminal;

[0110] A first detection module 502 is configured to detect whether a current first effective current of the first terminal is greater than a rated current of the converter;

[0111] The second control module 503 is used to adjust the duty cycle of the switch tube according to a second reference voltage to reduce the first effective current if the first effective current is greater than the rated current; wherein the second reference voltage is determined based on the first reference voltage, and the second reference voltage is less than the first reference voltage.

[0112] In one embodiment, the apparatus further comprises:

[0113] a second detection module, configured to detect whether the current operating state satisfies a constant power control condition after the second control module 503 adjusts the duty cycle of the switch tube according to the second reference voltage; the constant power control condition is used to indicate that the high current demand during the load startup process has ended;

[0114] A third control module is configured to determine a third reference voltage based on a preset constant power if the constant power control condition is met, and adjust the duty cycle of the switching tube based on the third reference voltage, wherein the preset constant power is related to the rated apparent power of the converter, the third reference voltage is greater than the second reference voltage, and the third reference voltage is less than or equal to the rated voltage of the converter.

[0115] In one embodiment, the working state includes a first time interval, and the second detection module is specifically used to determine the first time interval; wherein, the first time interval is the time interval between the time when the duty cycle of the switching tube is adjusted according to the second reference voltage and the current time; if the first time interval is greater than a preset first threshold, it is determined that the constant power control condition is met.

[0116] In one embodiment, the working state includes the current second effective current of the first end, and the second detection module is specifically used to detect whether the current second effective current of the first end is less than a preset current threshold; wherein the current threshold is equal to the product of the rated current and a preset coefficient, and the preset coefficient is equal to the ratio of the second reference voltage to the first reference voltage; if the second effective current is less than the current threshold, it is determined that the constant power control condition is met.

[0117] In one embodiment, the third control module is specifically configured to determine a candidate reference voltage based on the preset constant power and a third effective current currently at the first end; and determine a minimum voltage between the candidate reference voltage and the rated voltage as the third reference voltage.

[0118] In one embodiment, the third control module is specifically configured to obtain the candidate reference voltage by dividing the preset constant power by the third effective current.

[0119] In one embodiment, the apparatus further comprises:

[0120] a determination module, configured to, when the candidate reference voltage is the minimum voltage, determine a second time interval after the third control module adjusts the duty cycle of the switch tube according to the third reference voltage; wherein the second time interval is a time interval between the time when the duty cycle of the switch tube is adjusted according to the third reference voltage and a current time;

[0121] A fourth control module is configured to adjust the duty cycle of the switch tube according to the rated voltage if the second time interval is greater than a preset second threshold.

[0122] In one embodiment, the second control module 503 is further configured to multiply the first reference voltage by a preset coefficient to obtain the second reference voltage before adjusting the duty cycle of the switch tube according to the second reference voltage, where the preset coefficient is greater than 0 and less than 1.

[0123] Each module in the aforementioned converter control device may be implemented in whole or in part through software, hardware, or a combination thereof. Each module may be embedded in or independent of the converter's processor in hardware form, or may be stored in the converter's memory in software form, allowing the processor to call and execute the corresponding operations of each module.

[0124] In an exemplary embodiment, a converter is provided, the internal structure of which can be shown as follows: Figure 6As shown. The converter includes a processor, a memory, an input / output interface (Input / Output, abbreviated as I / O) and a communication interface. The processor, memory and input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. The processor of the converter is used to provide computing and control capabilities. The memory of the converter includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and computer program in the non-volatile storage medium. The database of the converter is used to store control data of the converter. The input / output interface of the converter is used to exchange information between the processor and an external device. The communication interface of the converter is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a control method of the converter is implemented.

[0125] Those skilled in the art will understand that Figure 6 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the converter to which the solution of the present application is applied. The specific converter may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0126] In an exemplary embodiment, a converter is provided, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, the following steps are implemented:

[0127] In off-grid mode and during startup of the load, setting a duty cycle of the switch in the converter according to a preset first reference voltage; wherein the duty cycle is related to the output voltage of the first end;

[0128] detecting whether a current first effective current of the first end is greater than a rated current of the converter;

[0129] If the first effective current is greater than the rated current, the duty cycle of the switch tube is adjusted according to a second reference voltage to reduce the first effective current; wherein the second reference voltage is determined according to the first reference voltage, and the second reference voltage is less than the first reference voltage.

[0130] In one embodiment, after adjusting the duty cycle of the switch according to the second reference voltage, the processor further implements the following steps when executing the computer program:

[0131] Detecting whether the current working state satisfies a constant power control condition; the constant power control condition is used to indicate that the high current demand during the load startup process has ended;

[0132] If the constant power control condition is met, a third reference voltage is determined according to a preset constant power, and the duty cycle of the switching tube is adjusted according to the third reference voltage, wherein the preset constant power is related to the rated apparent power of the converter, the third reference voltage is greater than the second reference voltage, and the third reference voltage is less than or equal to the rated voltage of the converter.

[0133] In one embodiment, the working state includes a first time interval, and the processor executes the computer program to specifically implement the following steps:

[0134] Determine a first time interval; wherein the first time interval is a time interval between a time at which the duty cycle of the switch tube is adjusted according to the second reference voltage and a current time;

[0135] If the first time interval is greater than a preset first threshold, it is determined that the constant power control condition is met.

[0136] In one embodiment, the working state includes a second effective current flowing through the first terminal, and the processor executes the computer program to implement the following steps:

[0137] detecting whether a second effective current currently flowing through the first terminal is less than a preset current threshold; wherein the current threshold is equal to a product of the rated current and a preset coefficient, and the preset coefficient is equal to a ratio of the second reference voltage to the first reference voltage;

[0138] If the second effective current is less than the current threshold, it is determined that the constant power control condition is met.

[0139] In one embodiment, when the processor executes the computer program, the following steps are specifically implemented:

[0140] determining a candidate reference voltage according to the preset constant power and a third effective current currently at the first end;

[0141] A minimum voltage between the candidate reference voltage and the rated voltage is determined as the third reference voltage.

[0142] In one embodiment, when the processor executes the computer program, the following steps are specifically implemented:

[0143] The candidate reference voltage is obtained by dividing the preset constant power by the third effective current.

[0144] In one embodiment, when the candidate reference voltage is the minimum voltage, after adjusting the duty cycle of the switch according to the third reference voltage, the processor further implements the following steps when executing the computer program:

[0145] Determine a second time interval; wherein the second time interval is a time interval between a time at which the duty cycle of the switch tube is adjusted according to the third reference voltage and a current time;

[0146] If the second time interval is greater than a preset second threshold, the duty cycle of the switch tube is adjusted according to the rated voltage.

[0147] In one embodiment, before adjusting the duty cycle of the switch according to the second reference voltage, the processor further implements the following steps when executing the computer program:

[0148] The first reference voltage is multiplied by a preset coefficient to obtain the second reference voltage, where the preset coefficient is greater than 0 and less than 1.

[0149] In one embodiment, an energy storage system is provided, which includes an energy storage battery and Figure 6 In the converter shown, the input end of the converter is connected to the energy storage battery, the first end of the converter is connected to the load, and the converter is used to supply power to the load.

[0150] The implementation solution provided by the energy storage system to solve the problem is similar to the implementation solution described in the above method. Therefore, the specific limitations in the embodiment of the energy storage system can be found in the above limitations on the control method of the converter, which will not be repeated here.

[0151] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0152] In off-grid mode and during startup of the load, setting a duty cycle of the switch in the converter according to a preset first reference voltage; wherein the duty cycle is related to the output voltage of the first end;

[0153] detecting whether a first effective current currently at the first end is greater than a rated current of the converter;

[0154] If the first effective current is greater than the rated current, the duty cycle of the switch tube is adjusted according to a second reference voltage to reduce the first effective current; wherein the second reference voltage is determined according to the first reference voltage, and the second reference voltage is less than the first reference voltage.

[0155] In one embodiment, after adjusting the duty cycle of the switch according to the second reference voltage, the computer program further implements the following steps when executed by the processor:

[0156] Detecting whether the current working state satisfies a constant power control condition; the constant power control condition is used to indicate that the high current demand during the load startup process has ended;

[0157] If the constant power control condition is met, a third reference voltage is determined according to a preset constant power, and the duty cycle of the switching tube is adjusted according to the third reference voltage, wherein the preset constant power is related to the rated apparent power of the converter, the third reference voltage is greater than the second reference voltage, and the third reference voltage is less than or equal to the rated voltage of the converter.

[0158] In one embodiment, the working state includes a first time interval, and when the computer program is executed by the processor, the following steps are specifically implemented:

[0159] Determine a first time interval; wherein the first time interval is a time interval between a time at which the duty cycle of the switch tube is adjusted according to the second reference voltage and a current time;

[0160] If the first time interval is greater than a preset first threshold, it is determined that the constant power control condition is met.

[0161] In one embodiment, the working state includes a second effective current flowing through the first terminal, and when the computer program is executed by the processor, the following steps are specifically implemented:

[0162] detecting whether a second effective current currently flowing through the first terminal is less than a preset current threshold; wherein the current threshold is equal to a product of the rated current and a preset coefficient, and the preset coefficient is equal to a ratio of the second reference voltage to the first reference voltage;

[0163] If the second effective current is less than the current threshold, it is determined that the constant power control condition is met.

[0164] In one embodiment, when the computer program is executed by a processor, the following steps are specifically implemented:

[0165] determining a candidate reference voltage according to the preset constant power and a third effective current currently at the first end;

[0166] A minimum voltage between the candidate reference voltage and the rated voltage is determined as the third reference voltage.

[0167] In one embodiment, when the computer program is executed by a processor, the following steps are specifically implemented:

[0168] The candidate reference voltage is obtained by dividing the preset constant power by the third effective current.

[0169] In one embodiment, when the candidate reference voltage is the minimum voltage, after adjusting the duty cycle of the switch according to the third reference voltage, the computer program further implements the following steps when executed by the processor:

[0170] Determine a second time interval; wherein the second time interval is a time interval between a time at which the duty cycle of the switch tube is adjusted according to the third reference voltage and a current time;

[0171] If the second time interval is greater than a preset second threshold, the duty cycle of the switch tube is adjusted according to the rated voltage.

[0172] In one embodiment, before adjusting the duty cycle of the switch according to the second reference voltage, the computer program further implements the following steps when executed by the processor:

[0173] The first reference voltage is multiplied by a preset coefficient to obtain the second reference voltage, where the preset coefficient is greater than 0 and less than 1.

[0174] In one embodiment, a computer program product is provided, comprising a computer program, which, when executed by a processor, implements the following steps:

[0175] In off-grid mode and during startup of the load, setting a duty cycle of the switch in the converter according to a preset first reference voltage; wherein the duty cycle is related to the output voltage of the first end;

[0176] detecting whether a current first effective current of the first end is greater than a rated current of the converter;

[0177] If the first effective current is greater than the rated current, the duty cycle of the switch tube is adjusted according to a second reference voltage to reduce the first effective current; wherein the second reference voltage is determined according to the first reference voltage, and the second reference voltage is less than the first reference voltage.

[0178] In one embodiment, after adjusting the duty cycle of the switch according to the second reference voltage, the computer program further implements the following steps when executed by the processor:

[0179] Detecting whether the current working state satisfies a constant power control condition; the constant power control condition is used to indicate that the high current demand during the load startup process has ended;

[0180] If the constant power control condition is met, a third reference voltage is determined according to a preset constant power, and the duty cycle of the switching tube is adjusted according to the third reference voltage, wherein the preset constant power is related to the rated apparent power of the converter, the third reference voltage is greater than the second reference voltage, and the third reference voltage is less than or equal to the rated voltage of the converter.

[0181] In one embodiment, the working state includes a first time interval, and when the computer program is executed by the processor, the following steps are specifically implemented:

[0182] Determine a first time interval; wherein the first time interval is a time interval between a time at which the duty cycle of the switch tube is adjusted according to the second reference voltage and a current time;

[0183] If the first time interval is greater than a preset first threshold, it is determined that the constant power control condition is met.

[0184] In one embodiment, the working state includes a second effective current flowing through the first terminal, and when the computer program is executed by the processor, the following steps are specifically implemented:

[0185] detecting whether a second effective current currently flowing through the first terminal is less than a preset current threshold; wherein the current threshold is equal to a product of the rated current and a preset coefficient, and the preset coefficient is equal to a ratio of the second reference voltage to the first reference voltage;

[0186] If the second effective current is less than the current threshold, it is determined that the constant power control condition is met.

[0187] In one embodiment, when the computer program is executed by a processor, the following steps are specifically implemented:

[0188] determining a candidate reference voltage according to the preset constant power and a third effective current currently at the first end;

[0189] A minimum voltage between the candidate reference voltage and the rated voltage is determined as the third reference voltage.

[0190] In one embodiment, when the computer program is executed by a processor, the following steps are specifically implemented:

[0191] The candidate reference voltage is obtained by dividing the preset constant power by the third effective current.

[0192] In one embodiment, when the candidate reference voltage is the minimum voltage, after adjusting the duty cycle of the switch according to the third reference voltage, the computer program further implements the following steps when executed by the processor:

[0193] Determine a second time interval; wherein the second time interval is a time interval between a time at which the duty cycle of the switch tube is adjusted according to the third reference voltage and a current time;

[0194] If the second time interval is greater than a preset second threshold, the duty cycle of the switch tube is adjusted according to the rated voltage.

[0195] In one embodiment, before adjusting the duty cycle of the switch according to the second reference voltage, the computer program further implements the following steps when executed by the processor:

[0196] The first reference voltage is multiplied by a preset coefficient to obtain the second reference voltage, where the preset coefficient is greater than 0 and less than 1.

[0197] Those skilled in the art will understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. In particular, any reference to memory, database, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The databases involved in the various embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the various embodiments provided herein may be, but are not limited to, general-purpose processors, central processing units (CPUs), graphics processing units (GPUs), digital signal processors (DSPs), programmable logic devices (PLDs), quantum computing-based data processing logic devices, artificial intelligence (AI) processors, and the like.

[0198] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0199] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A method for controlling a converter, characterized in that: Applied to a converter, wherein a first end of the converter is connected to a load, and the converter is used to supply power to the load, the method includes: In off-grid mode and during startup of the load, setting a duty cycle of the switch in the converter according to a preset first reference voltage; wherein the duty cycle is related to the output voltage of the first end; detecting whether a current first effective current of the first end is greater than a rated current of the converter; If the first effective current is greater than the rated current, the duty cycle of the switch tube is adjusted according to a second reference voltage to reduce the first effective current; wherein the second reference voltage is determined according to the first reference voltage, and the second reference voltage is less than the first reference voltage.

2. The method according to claim 1, characterized in that After adjusting the duty cycle of the switch tube according to the second reference voltage, the method further includes: Detecting whether the current working state satisfies a constant power control condition; the constant power control condition is used to indicate that the high current demand during the load startup process has ended; If the constant power control condition is met, a third reference voltage is determined according to a preset constant power, and the duty cycle of the switching tube is adjusted according to the third reference voltage, wherein the preset constant power is related to the rated apparent power of the converter, the third reference voltage is greater than the second reference voltage, and the third reference voltage is less than or equal to the rated voltage of the converter.

3. The method according to claim 2, characterized in that The operating state includes a first time interval, and detecting whether the current operating state satisfies a constant power control condition includes: Determine the first time interval; wherein the first time interval is the time interval between the time when the duty cycle of the switch tube is adjusted according to the second reference voltage and the current time; If the first time interval is greater than a preset first threshold, it is determined that the constant power control condition is met.

4. The method according to claim 2, characterized in that The working state includes a current second effective current of the first terminal, and detecting whether the current working state satisfies a constant power control condition includes: detecting whether a second effective current currently flowing through the first terminal is less than a preset current threshold; wherein the current threshold is equal to a product of the rated current and a preset coefficient, and the preset coefficient is equal to a ratio of the second reference voltage to the first reference voltage; If the second effective current is less than the current threshold, it is determined that the constant power control condition is met.

5. The method according to any one of claims 2 to 4, characterized in that: The determining of the third reference voltage according to the preset constant power includes: determining a candidate reference voltage according to the preset constant power and a third effective current currently at the first end; A minimum voltage between the candidate reference voltage and the rated voltage is determined as the third reference voltage.

6. The method according to claim 5, characterized in that The determining of a candidate reference voltage according to the preset constant power and a third effective current currently at the first terminal includes: The candidate reference voltage is obtained by dividing the preset constant power by the third effective current.

7. The method according to claim 5, characterized in that When the candidate reference voltage is the minimum voltage, after adjusting the duty cycle of the switch tube according to the third reference voltage, the method further includes: Determine a second time interval; wherein the second time interval is a time interval between a time at which the duty cycle of the switch tube is adjusted according to the third reference voltage and a current time; If the second time interval is greater than a preset second threshold, the duty cycle of the switch tube is adjusted according to the rated voltage.

8. The method according to claim 1, characterized in that Before adjusting the duty cycle of the switch tube according to the second reference voltage, the method further includes: The first reference voltage is multiplied by a preset coefficient to obtain the second reference voltage, where the preset coefficient is greater than 0 and less than 1.

9. A converter comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 8 are implemented.

10. An energy storage system, characterized in that: It comprises an energy storage battery and the converter as claimed in claim 9, wherein the input end of the converter is connected to the energy storage battery, the first end of the converter is connected to the load, and the converter is used to supply power to the load.

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