Control method and related device of DC-DC converter

Abstract

The present application provides a control method and related device for a DC-DC converter, which is applied to a DC-DC converter, and the method includes: obtaining a DC bus voltage; if the DC bus voltage is greater than a first preset voltage, determining whether it meets a first preset condition, the first preset condition being that the battery pack of the same group corresponding to the DC-DC converter has a charging demand, and the working modes of other DC-DC converters are all hot backup modes; if it meets the requirements, switching its own working mode to a charging mode; if it does not meet the requirements, switching its own working mode to a hot backup mode, and the main power MOS tube remains in a normally off state in the hot backup mode. In this way, the switching loss of the MOS tube can be reduced, and the working mode can be switched in time in response to the energy transmission demand quickly, and the situation of DC bus overload caused by charging multiple battery packs at the same time can be avoided, thereby improving the safety and stability of the system.

Description

Technical Field

[0001] The present application relates to the field of electronic power, and in particular to a control method and related devices for a DC-DC converter. Background Art

[0002] With the rapid development of power electronics technology, bidirectional DC-DC converters are used in more and more scenarios. For example, in a DC bus power supply system, its main purpose is to support the DC bus voltage through the battery pack in time when the DC bus loses power to ensure the normal operation of the DC load, and to charge the battery pack when the DC bus voltage is normal.

[0003] However, the bidirectional DC-DC converter in the prior art has large switching losses in light load and no-load states, and the charge and discharge control of the bidirectional DC-DC converter in the prior art is not reasonable. For example, when the charging demand sent by the battery management system (BMS) of the same battery pack is detected, the charging mode will be immediately switched to charge the battery pack, resulting in the system having multiple battery packs being charged at the same time. When multiple battery packs are charged at the same time, if the rated DC load is suddenly added so that the DC load side reaches the rated output capacity of the DC bus, there will be a risk of overload and voltage drop of the DC bus. Summary of the invention

[0004] The embodiments of the present application provide a control method and related devices for a DC-DC converter, in order to optimize the control logic of the DC-DC converter, reduce the switching loss of the MOS tube, and avoid the situation where the DC bus is overloaded due to the simultaneous charging of multiple battery packs, thereby improving the safety and stability of the system.

[0005] In a first aspect, an embodiment of the present application provides a control method for a DC-DC converter, which is applied to a DC-DC converter in a DC bus power supply system, wherein the DC bus power supply system includes a plurality of DC-DC converters, a plurality of battery packs, and a DC load, wherein the plurality of DC-DC converters and the plurality of battery packs are connected in a one-to-one correspondence, and each DC-DC converter is connected to the DC load via a DC bus, and the method includes:

[0006] Get the DC bus voltage;

[0007] If the DC bus voltage is greater than the first preset voltage, it is determined whether a first preset condition is met, wherein the first preset condition refers to that the battery group in the same group corresponding to the DC-DC converter has a charging demand, and the working modes of other DC-DC converters are all hot backup modes, and the working modes include the hot backup mode, the charging mode and the discharging mode. The hot backup mode refers to a working mode in which the MOS tube of the DC-DC converter remains in a normally off state, the charging mode refers to a working mode in which the MOS tube of the DC-DC converter remains in a normally on state so that energy flows to the battery group in the same group, and the discharging mode refers to a working mode in which the MOS tube of the DC-DC converter remains in a normally on state so that energy flows to the DC bus;

[0008] If it meets the requirements, the operating mode is switched to the charging mode;

[0009] If not, the operating mode is switched to the hot standby mode.

[0010] In a second aspect, an embodiment of the present application provides a control device for a DC-DC converter, which is applied to a DC-DC converter in a DC bus power supply system, wherein the DC bus power supply system includes a plurality of DC-DC converters, a plurality of battery packs, and a DC load, wherein the plurality of DC-DC converters and the plurality of battery packs are connected in a one-to-one correspondence, and each DC-DC converter is connected to the DC load through a DC bus, and the device includes:

[0011] An acquisition unit, used for acquiring a DC bus voltage;

[0012] a judgment unit, configured to judge whether a first preset condition is met if the DC bus voltage is greater than a first preset voltage, wherein the first preset condition refers to that a battery group in the same group corresponding to the DC-DC converter has a charging demand, and the working modes of other DC-DC converters are all hot backup modes, wherein the working modes include the hot backup mode, the charging mode, and the discharging mode, wherein the hot backup mode refers to a working mode in which the MOS tube of the DC-DC converter remains in a normally off state, the charging mode refers to a working mode in which the MOS tube of the DC-DC converter remains in a normally on state so that energy flows to the battery group in the same group, and the discharging mode refers to a working mode in which the MOS tube of the DC-DC converter remains in a normally on state so that energy flows to the DC bus;

[0013] A switching unit is used to switch its own working mode to the charging mode if the conditions are met; and to switch its own working mode to the hot backup mode if the conditions are not met.

[0014] In a third aspect, an embodiment of the present application provides a DC-DC converter, comprising a controller, the controller comprising a processor, a memory, and one or more programs, the one or more programs being stored in the memory and configured to be executed by the processor, the program comprising instructions for executing the steps in the first aspect of the embodiment of the present application.

[0015] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium having a computer program / instructions stored thereon, which, when executed by a processor, implement the steps in the first aspect of the embodiment of the present application.

[0016] It can be seen that in the embodiment of the present application, after the DC-DC converter in the DC bus power supply system obtains the DC bus voltage, if the DC bus voltage is greater than the first preset voltage, it is determined whether it meets the first preset condition, and the first preset condition refers to that the DC-DC converter has a charging demand corresponding to the same group of battery groups, and the working modes of other DC-DC converters are all hot backup mode; if it meets the requirements, the DC-DC converter switches its own working mode to the charging mode; if it does not meet the requirements, the DC-DC converter switches its own working mode to the hot backup mode. In this way, under normal working conditions of the mains, even if the same group of battery groups has a charging demand, the DC-DC converter will not immediately switch to the charging mode, but detect the status of other DC-DC converters, and only when other DC-DC converters are in the hot backup mode will it switch to the charging mode to charge the same group of battery groups, otherwise it will switch to the hot backup mode, and the main power MOS tube in the hot backup mode remains in the normally off state, which can not only reduce the switching loss of the MOS tube, but also quickly respond to the energy transmission demand and switch the working mode in time, and at the same time avoid the situation where multiple battery groups are charged at the same time and cause the DC bus to be overloaded, thereby improving the safety and stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a structural block diagram of a DC bus power supply system provided in an embodiment of the present application;

[0019] Figure 2 It is a flow chart of a control method of a DC-DC converter provided in an embodiment of the present application;

[0020] Figure 3 is an example schematic diagram of a rotating switching discharge module provided in an embodiment of the present application;

[0021] Figure 4 It is a schematic diagram of energy flow of a DC bus power supply system in a charging mode provided in an embodiment of the present application;

[0022] Figure 5 is a schematic diagram of energy flow in a DC bus power supply system in a discharge mode provided in an embodiment of the present application;

[0023] Figure 6 It is a schematic diagram of energy flow of a DC bus power supply system in a hot backup mode provided by an embodiment of the present application;

[0024] Figure 7 is a structural block diagram of a control device for a DC-DC converter provided in an embodiment of the present application;

[0025] Figure 8 is a structural block diagram of another control device of a DC-DC converter provided in an embodiment of the present application;

[0026] Fig. 9 It is a structural block diagram of a DC-DC converter provided in an embodiment of the present application. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0028] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.

[0029] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0030] See also Figure 1 , Figure 1 is a structural block diagram of a DC bus power supply system provided in an embodiment of the present application. Figure 1 As shown, the DC bus power supply system 10 includes a plurality of DC-DC converters 11, a plurality of battery packs 12 and a DC load 13, wherein the plurality of DC-DC converters 11 and the plurality of battery packs 12 are connected one by one, and each DC-DC converter 11 is connected to the DC load 13 through a DC bus 14. Wherein, the DC-DC converter 11 in the embodiment of the present application specifically refers to a bidirectional DC-DC converter, and the energy flow direction is controlled by controlling the opening and closing of the MOS tube. In this example, the DC bus power supply system 10 also includes an AC-DC converter 15, wherein the first end of the AC-DC converter 15 is connected to the mains terminal, specifically to the three-phase input terminal connected to the mains terminal through phase A, phase B, and phase C, and is connected to the protective ground wire in the mains terminal through PE, the second end is connected to the DC load 13 through the DC bus 14, and the third end is connected to the monitoring module 17 through the CAN bus 16, and the monitoring module 17 is used to monitor the state of the DC bus power supply system 10. The plurality of DC-DC converters 11 and the plurality of battery packs 12 are all connected to a CAN bus to exchange status information in real time.

[0031] A control method for a DC-DC converter provided in an embodiment of the present application is described below.

[0032] See also Figure 2 , Figure 2 is a flow chart of a control method of a DC-DC converter provided in an embodiment of the present application, which is applied to Figure 1 In the DC-DC converter 11 shown in FIG. Figure 2 As shown, the method includes:

[0033] S201, obtaining a DC bus voltage.

[0034] The DC-DC converter can exchange status information via a CAN bus to obtain a voltage value of the DC bus.

[0035] S202: If the DC bus voltage is greater than a first preset voltage, determine whether a first preset condition is met.

[0036] If it is in compliance, execute S203; if it is not in compliance, execute S204.

[0037] Among them, the first preset condition means that there is a charging demand for the same battery group corresponding to the DC-DC converter, and the working modes of other DC-DC converters are all hot backup modes, and the working modes include the hot backup mode, the charging mode and the discharging mode. The hot backup mode refers to the working mode in which the MOS tube of the DC-DC converter remains in a normally off state, the charging mode refers to the working mode in which the MOS tube of the DC-DC converter remains in a normally on state to allow energy to flow to the same battery group, and the discharging mode refers to the working mode in which the MOS tube of the DC-DC converter remains in a normally on state to allow energy to flow to the DC bus.

[0038] Among them, the hot backup mode is essentially a discharge mode without energy transmission. In the hot backup mode, the main power MOS tube remains in a normally off state, which can not only reduce switching losses, but also quickly respond to energy transmission requirements and avoid DC bus power failure.

[0039] S203, switching its own working mode to the charging mode.

[0040] S204, switching its own working mode to the hot backup mode.

[0041] Among them, the first preset voltage is an empirical value obtained through preliminary statistical analysis of data, which can be used to monitor the voltage state of the DC bus. In this example, the DC bus voltage is greater than the first preset voltage, indicating that the DC bus is not powered off, and the DC-DC converter does not need to take power from the battery pack for support. At this time, if it is detected that there is a charging demand for the same group of battery packs, and the working modes of other DC-DC converters are all hot backup modes, then switch its own working mode to charging mode and charge the same group of battery packs. If the working modes of other DC-DC converters are not all hot backup modes, charging of the same group of batteries is not allowed, and switch its own working mode to hot backup mode. For example, when the working mode of other DC-DC converters is charging mode, if the same group of battery packs are still charged at this time, there will be a situation where multiple groups of battery packs are charged at the same time in the system, which will cause the DC bus to be overloaded. Risk.

[0042] In other embodiments, when the mains power is cut off, there are other DC-DC converters in the system that work in a discharge mode to support the DC bus, and the system energy flows from the battery pack to the DC bus. If the same battery pack is still charged at this time, the energy flows from the DC bus to the battery pack, that is, the energy flow in the system conflicts, resulting in a lower overall energy transfer efficiency of the system, and causing the DC load side to jump from a light load to a rated DC load, which still causes an overload risk to the DC bus. Also, in the design of a DC bus power supply system, it is usually designed as an N+1 redundant backup solution, that is, when the mains power is cut off, the total power of N DC-DC converters meets the maximum output power of the DC bus, and at the same time backs up 1 redundant DC-DC converter to improve the reliability of the system. If the battery pack is charged at this time, the system will no longer have N+1 redundant backup capabilities.

[0043] It can be seen that in this example, after the DC-DC converter in the DC bus power supply system obtains the DC bus voltage, if the DC bus voltage is greater than the first preset voltage, it is determined whether it meets the first preset condition, which means that the DC-DC converter has a charging demand for the same battery group and the working modes of other DC-DC converters are all hot backup mode; if it meets the conditions, it switches its own working mode to the charging mode; if it does not meet the conditions, it switches its own working mode to the hot backup mode. In this way, when the mains power is normal, even if the same battery group has a charging demand, the DC-DC converter will not immediately switch to the charging mode, but detect the status of other DC-DC converters. Only when other DC-DC converters are in the hot backup mode will it switch to the charging mode to charge the same battery group, otherwise it will switch to the hot backup mode, and the main power MOS tube in the hot backup mode remains in the normally off state, which can not only reduce the switching loss of the MOS tube, but also quickly respond to the energy transmission demand and switch the working mode in time, and also avoid the situation where multiple battery groups are charged at the same time and cause the DC bus to be overloaded, thereby improving the safety and stability of the system.

[0044] In one possible example, before determining whether the first preset condition is met, the method further includes: adjusting the set voltage on the DC bus side of the DC-DC converter to the first preset voltage, so that the DC-DC converter can increase the energy transfer efficiency when the DC bus voltage is less than the first preset voltage.

[0045] The set voltage on the DC bus side of the DC-DC converter is a voltage that can be adjusted in real time, and the voltage is adjusted in real time to monitor different voltage states of the DC bus voltage. In this example, the voltage state of the DC bus is in a normal state, and the voltage is set to a first preset voltage to continuously monitor whether the DC bus voltage drops, and after the DC bus voltage drops, due to the voltage difference on both sides of the DC bus, the DC-DC converter can increase the transmission energy in time to pull the DC bus voltage up to a normal level.

[0046] It can be seen that in this example, when the voltage state of the DC bus is in a normal state, the DC-DC converter first adjusts the set voltage on its own DC bus side to the first preset voltage before determining whether the first preset condition is met, so that it can continuously monitor the state of the DC bus voltage, and then after the DC bus voltage drops, it can promptly increase the transmission energy to raise the DC bus voltage to a normal level, thereby ensuring the normal operation of the DC load.

[0047] In a possible example, after obtaining the DC bus voltage, the method further includes: if the DC bus voltage is less than or equal to the first preset voltage, determining whether a discharge prohibition instruction of the same battery group is received; if so, switching its own working mode to the hot backup mode; if not, switching its own working mode to the discharge mode; sending its own output power to a target DC-DC converter among the multiple DC-DC converters, so that the target DC-DC converter generates multiple control signals corresponding to the multiple DC-DC converters one by one according to the output power of each DC-DC converter; receiving a target control signal from the target DC-DC converter, and switching its own working mode according to the target control signal.

[0048] Among them, when the DC bus voltage is less than or equal to the first preset voltage, it indicates that the DC bus is powered off or there is a risk of power off. At this time, the mains end is abnormal or powered off, and the DC-DC converter needs to take power from the battery pack to support the DC bus to ensure the normal operation of the DC load. In this example, after detecting that the DC bus voltage is less than or equal to the first preset voltage, the DC-DC converter first determines whether a discharge prohibition instruction of the same battery pack is received. Among them, the state of the battery pack includes a full-charge state, a non-full-charge state, an undervoltage state, and a protection state. The full-charge state is used to characterize that the battery pack is allowed to discharge and there is no charging demand; the non-full-charge state is used to characterize that the battery pack is allowed to discharge and there is a charging demand; the undervoltage state is used to characterize that the battery pack is prohibited from discharging and there is a charging demand; the protection state is used to characterize that the battery pack is prohibited from discharging and there is no charging demand. When the battery pack is in an undervoltage state or a protection state, the discharge prohibition instruction is uploaded to the CAN bus through the BMS, so that the DC-DC converter can receive the discharge prohibition instruction through the CAN bus.

[0049] If the same group of batteries is allowed to discharge, the DC-DC converter immediately switches to the discharge mode to support the DC bus. After a period of time, the voltage and current of its own output are in a steady state. At this time, the output power of the target DC-DC converter is sent through the CAN bus. Among them, the output power sent specifically includes the rated power of the DC-DC converter and the actual output power in the current state. Among them, the target DC-DC converter is a pre-set master module for coordinating the charging and discharging behaviors of multiple DC-DC converters among multiple DC-DC converters. It can be specifically defined according to the number of the DC-DC converter, for example, the DC-DC converter numbered 1 is the master module, and the DC-DC converters of other numbers are all slave modules. In this example, the target DC-DC converter can receive the output power of the DC-DC converters that all battery packs allow to discharge, and based on this, generate multiple control signals corresponding to multiple DC-DC converters one by one. Among them, the control signal is used to indicate discharge or no discharge. It can be understood that it takes a certain time for the master module to generate a control signal based on the output power uploaded by each slave module. During this period, the DC-DC converter will continue to maintain the discharge mode to support the DC bus that has lost power, ensuring that the capacity to support the bus is sufficient, until it receives the target control signal from the target DC-DC converter and switches its own working mode according to the target control signal.

[0050] It can be seen that in this example, when the DC bus voltage is less than or equal to the first preset voltage, the battery group needs to discharge to support the DC bus. At this time, the DC-DC converter determines whether it has received a prohibition discharge instruction from the same battery group. If so, it switches to the hot backup mode. If not, it immediately switches its own working mode to the discharge mode to support the DC bus, and sends its own output power to the target DC-DC converter after the output voltage and current are stable to wait for the generation of the control signal. After receiving the target control signal, it switches its own working mode according to the target control signal. In this way, when the system needs the battery group to discharge to support the DC bus, the DC-DC converter will first determine the state of the same battery group, maintain the hot backup mode when discharging is prohibited, so that the main power MOS tube remains in a normally off state, which can reduce the switching loss of the MOS tube and quickly respond to the energy transmission demand and switch the working mode in time; at the same time, when discharging is allowed, it immediately switches to the discharge mode to support the DC bus, and uploads the output power to the main module after the output is stable. The main module coordinates and manages the discharge control of each DC-DC converter, making the system discharge control more reasonable, reducing the overall loss of the system, and improving the system life.

[0051] In other possible examples, after determining that the discharging prohibition instruction of the same battery group is not received, the method further includes: switching its own working mode to the discharging mode; sending its own output power to the target DC-DC converter among the multiple DC-DC converters; if the control signal of the target DC-DC converter is not detected when the count of the discharge timer reaches the preset value, switching its own working mode to the hot backup mode. Wherein, the preset value is an empirical value obtained by pre-statistical analysis, which is used to characterize the time required from the detection of the DC bus voltage power failure to the target DC-DC converter outputting the control signal. In this example, when the DC bus voltage is greater than the first preset voltage, the discharge timer in the DC bus power supply system is assigned to 0, and when it is detected that the DC bus voltage is less than or equal to the first preset voltage, that is, when the DC bus is powered off, the discharge timer is controlled to start counting, so as to count the discharge time of each DC-DC converter in real time after the DC bus is powered off. When the count of the discharge timer reaches the preset value and the control signal is not detected, the DC-DC converter determines by default that the target DC-DC converter does not indicate discharge.

[0052] In a possible example, switching its own working mode according to the target control signal includes: if the target control signal indicates discharge, switching its own working mode to the discharge mode; if the target control signal does not indicate discharge, adjusting the set voltage on the DC bus side of the DC-DC converter to a second preset voltage, and switching its own working mode to the hot backup mode; when the DC bus voltage is less than or equal to the second preset voltage, switching its own working mode to the discharge mode.

[0053] Wherein, if the target control signal indicates discharge, that is, the target DC-DC converter, after calculation and coordination, instructs the DC-DC converter to take power from the battery pack to support the DC bus, then continue to maintain its own working mode as the discharge mode. If the target control signal does not indicate discharge, that is, the target DC-DC converter does not instruct the DC-DC converter to take power from the battery pack to support the DC bus after calculation and coordination, then the set voltage on its own DC bus side is adjusted to the second preset voltage, and switched to the hot backup mode. Wherein, the second preset voltage has a similar function to the above-mentioned first preset voltage, and is used to continuously monitor whether the DC bus voltage will further drop, and to increase the energy transmission in time after the drop. In this example, the DC bus has been powered off, and the target DC-DC converter does not indicate self-discharge. At this time, the DC-DC converter switches to the hot backup mode, but it still needs to continuously monitor whether the DC bus voltage will further drop. When it drops further, that is, when the DC bus voltage is less than or equal to the second preset voltage, it switches to the discharge mode to support the DC bus. It can be understood that the second preset voltage is less than the first preset voltage. In this example, the second preset voltage is equal to the first preset voltage minus the secondary hot backup mode difference voltage, and the secondary hot backup mode difference voltage is used to characterize the degree of further power loss of the DC bus.

[0054] It can be seen that in this example, when a control signal indicating discharge is received, its own working mode is switched to the discharge mode. When a control signal not indicating discharge is received, the set voltage on its own DC bus side is adjusted to the second preset voltage, and its own working mode is switched to the hot backup mode, so as to continuously monitor whether the DC bus voltage is further powered off, and when the DC bus voltage is less than or equal to the second preset voltage, its own working mode is switched to the discharge mode to support the DC bus. In this way, the DC-DC converter can respond to the instructions issued by the target DC-DC converter after calculation and coordination, and can also avoid further power loss of the DC bus, thereby improving the safety and stability of the system.

[0055] In a possible example, sending its own output power to a target DC-DC converter among the multiple DC-DC converters so that the target DC-DC converter generates multiple control signals corresponding to the multiple DC-DC converters one by one according to the output power of each DC-DC converter, includes: sending its own output power to a target DC-DC converter among the multiple DC-DC converters so that the target DC-DC converter performs the following operations: calculating the total output power according to the output power of each DC-DC converter; calculating the minimum required quantity according to the total output power and the rated power of each DC-DC converter; generating X first control signals and Y second control signals; wherein Y=NX, X is the minimum required quantity, N is the number of DC-DC converters in the DC bus power supply system, and the first control signal indicates discharge, and the second control signal does not indicate discharge.

[0056] After receiving the actual output power and rated power of each DC-DC converter, the target DC-DC converter calculates the total output power, which specifically refers to the sum of the actual output power of each DC-DC converter. The minimum required number X required to work in the current discharge activity is further calculated based on the total output power and the rated power of each DC-DC converter, and then X first control signals indicating discharge and (NX) second control signals not indicating discharge are generated to comprehensively manage the discharge control of each DC-DC converter, so that the discharge control of the system is more reasonable.

[0057] It can be seen that in this example, after the DC-DC converter sends its own output power to the target DC-DC converter, the target DC-DC converter calculates the total output power of the system, and then calculates the minimum required number of DC-DC converters that need to be switched to the discharge mode, and generates a corresponding number of first control signals indicating discharge and a remaining number of second control signals that do not indicate discharge. In this way, the N DC-DC converters in the system do not need to be switched to the discharge mode, and only the minimum DC-DC converters are used to support the DC bus, which effectively reduces the overall loss of the system and increases the system life.

[0058] In a possible example, the rated power of each DC-DC converter is the same, and the minimum required quantity is calculated by the target DC-DC converter according to the total output power and the rated power of each DC-DC converter by the following formula: X= CEILING(P1 / P2).

[0059] Wherein, CEILING() is a round-up function, P1 is the total output power, and P2 is the rated power of each DC-DC converter. For example, assuming that P1 is 2500W and P2 is 300W, it can be calculated that the minimum required number X is 9, that is, at least 9 DC-DC converters are required to switch to the discharge mode to draw power from the corresponding battery pack to support the DC bus. In other embodiments, the ROUNDUP function can also be used to calculate the minimum required number X, which is not the only limitation here.

[0060] It can be seen that in this example, the target DC-DC converter calculates the minimum required number of DC-DC converters that need to be switched to the discharge mode in the current discharge activity by calling the CEILING function, thereby improving the accuracy of the calculation result.

[0061] In a possible example, after generating X first control signals and Y second control signals, the target DC-DC converter further performs the following operations: dividing the multiple DC-DC converters into a first queue and a second queue, the first queue including X DC-DC converters, and the second queue including Y DC-DC converters; performing the following operations for the first queue and the second queue: sending the first control signal to each DC-DC converter in the first queue; sending the second control signal to each DC-DC converter in the second queue; after a preset time period, moving the first DC-DC converter in the first queue to the end of the queue of the second queue, and moving the first DC-DC converter in the second queue to the end of the queue of the first queue, so as to update the first queue and the second queue; repeating the above operations until the DC bus voltage is greater than the first preset voltage.

[0062] Wherein, the division of the plurality of DC-DC converters into the first queue and the second queue may be specifically divided according to the number of each DC-DC converter. For example, the DC-DC converters numbered 1 to X are placed in the first queue, and the DC-DC converters numbered X+1 to N are placed in the second queue, that is, the first queue includes the first X DC-DC converters, and the second queue includes the last Y DC-DC converters. After the queue division is completed, X first control signals are sent to the X DC-DC converters in the first queue, so that the X DC-DC converters switch their own working mode to the discharge mode according to the first control signal; and Y second control signals are sent to the Y DC-DC converters in the second queue, so that the Y DC-DC converters adjust the set voltage on their own DC bus side to the second preset voltage according to the second control signal and switch their own working mode to the hot backup mode, so as to continuously monitor whether the DC bus is further powered off.

[0063] After a preset time, the target DC-DC converter moves the first DC-DC converter in the first queue to the end of the second queue, and moves the first DC-DC converter in the second queue to the end of the first queue. For example, the first queue includes DC-DC converters numbered 1 to X, and the second queue includes DC-DC converters numbered X+1 to N. Figure 3 As shown, the DC-DC converter numbered 1 is moved to the end of the second queue, and the DC-DC converter numbered X+1 is moved to the end of the first queue to obtain the updated first queue and second queue, and then the above process is repeated, that is, X first control signals are sent to the updated first queue, and Y second control signals are sent to the updated second queue and the discharge is continued for a preset time.

[0064] It can be seen that in this example, after the target DC-DC converter divides the multiple DC-DC converters in the DC bus power supply system into the first queue and the second queue, it sends corresponding control signals to centrally manage the discharge behavior of the system, and switches the discharge modules in turn to balance the working hours of all DC-DC converters, thereby effectively extending the system life.

[0065] In order to better understand the present application, the energy flow of the DC bus power supply system in different working modes is described below with reference to the accompanying drawings. Figure 4 , Figure 4 Schematic diagram of energy flow of a DC bus power supply system in a charging mode provided in an embodiment of the present application. Figure 4 As shown in Figure 1, when the DC-DC converter switches to charging mode, energy flows from the DC bus to the battery pack. At the same time, the DC bus normally supplies power to the DC load, and energy flows from the DC bus to the DC load. Figure 5 , Figure 5 Schematic diagram of energy flow of a DC bus power supply system in a discharge mode provided in an embodiment of the present application. Figure 5 As shown in the figure, when the DC bus loses power or is abnormal, the DC-DC converter switches to the discharge mode to draw power from the battery pack to support the DC bus. Energy flows from the battery pack to the DC bus, so that the DC bus voltage is sufficient to ensure the normal operation of the DC load, and energy flows from the DC bus to the DC load. Figure 6 , Figure 6 Schematic diagram of energy flow of a DC bus power supply system in hot backup mode provided by an embodiment of the present application, such as Figure 6As shown, it is assumed that this example is a situation where the AC power end is normal and no DC-DC converter is needed for power support. At this time, the working modes of the DC-DC converters in the system are all hot backup mode, and there is no energy flow. At the same time, the AC power end normally supplies power to the DC bus through the AC-DC converter to ensure the normal operation of the DC load, and energy flows from the DC bus to the DC load.

[0066] In accordance with the above-mentioned embodiment, please refer to Figure 7 , Figure 7 is a structural block diagram of a control device for a DC-DC converter provided in an embodiment of the present application, wherein the control device for the DC-DC converter is applied to Figure 1 In the DC-DC converter 11 shown, the control device 70 of the DC-DC converter includes: an acquisition unit 701, which is used to acquire a DC bus voltage; a judgment unit 702, which is used to judge whether a first preset condition is met if the DC bus voltage is greater than a first preset voltage, wherein the first preset condition refers to that there is a charging demand for the battery group in the same group corresponding to the DC-DC converter, and the working modes of other DC-DC converters are all hot backup modes, and the working modes include the hot backup mode, the charging mode and the discharging mode, the hot backup mode refers to a working mode in which the MOS tube of the DC-DC converter remains in a normally off state, the charging mode refers to a working mode in which the MOS tube of the DC-DC converter remains in a normally on state so that energy flows to the battery group in the same group, and the discharging mode refers to a working mode in which the MOS tube of the DC-DC converter remains in a normally on state so that energy flows to the DC bus; a switching unit 703, which is used to switch its own working mode to the charging mode if the condition is met; and, if the condition is not met, switch its own working mode to the hot backup mode.

[0067] In a possible example, before judging whether the first preset condition is met, the control device 70 of the DC-DC converter is also used to: adjust the set voltage on the DC bus side of the DC-DC converter to the first preset voltage, so that the DC-DC converter can increase the energy transfer efficiency when the DC bus voltage is less than the first preset voltage.

[0068] In a possible example, after obtaining the DC bus voltage, the control device 70 of the DC-DC converter is further used to: if the DC bus voltage is less than or equal to the first preset voltage, determine whether a discharge prohibition instruction of the same battery group is received; if so, switch its own working mode to the hot backup mode; if not, switch its own working mode to the discharge mode; send its own output power to a target DC-DC converter among the multiple DC-DC converters, so that the target DC-DC converter generates multiple control signals corresponding to the multiple DC-DC converters one by one according to the output power of each DC-DC converter; receive a target control signal from the target DC-DC converter, and switch its own working mode according to the target control signal.

[0069] In one possible example, in terms of switching its own working mode according to the target control signal, the control device 70 of the DC-DC converter is specifically used to: if the target control signal indicates discharge, switch its own working mode to the discharge mode; if the target control signal does not indicate discharge, adjust the set voltage on the DC bus side of the DC-DC converter to a second preset voltage, and switch its own working mode to the hot backup mode; when the DC bus voltage is less than or equal to the second preset voltage, switch its own working mode to the discharge mode.

[0070] In a possible example, in terms of sending its own output power to a target DC-DC converter among the multiple DC-DC converters so that the target DC-DC converter generates multiple control signals corresponding to the multiple DC-DC converters one by one according to the output power of each DC-DC converter, the control device 70 of the DC-DC converter is specifically used to: send its own output power to a target DC-DC converter among the multiple DC-DC converters so that the target DC-DC converter performs the following operations: calculate the total output power according to the output power of each DC-DC converter; calculate the minimum required quantity according to the total output power and the rated power of each DC-DC converter; generate X first control signals and Y second control signals; wherein Y=NX, X is the minimum required quantity, N is the number of DC-DC converters in the DC bus power supply system, and the first control signal indicates discharge, and the second control signal does not indicate discharge.

[0071] In a possible example, the rated power of each DC-DC converter is the same, and the minimum required quantity is calculated by the target DC-DC converter according to the total output power and the rated power of each DC-DC converter by using the following formula:

[0072] X = CEILING(P1 / P2);

[0073] Wherein, CEILING() is a rounding-up function, P1 is the total output power, and P2 is the rated power of each DC-DC converter.

[0074] In a possible example, after generating X first control signals and Y second control signals, the target DC-DC converter further performs the following operations: dividing the multiple DC-DC converters into a first queue and a second queue, the first queue including X DC-DC converters, and the second queue including Y DC-DC converters; performing the following operations for the first queue and the second queue: sending the first control signal to each DC-DC converter in the first queue; sending the second control signal to each DC-DC converter in the second queue; after a preset time period, moving the first DC-DC converter in the first queue to the end of the queue of the second queue, and moving the first DC-DC converter in the second queue to the end of the queue of the first queue, so as to update the first queue and the second queue; repeating the above operations until the DC bus voltage is greater than the first preset voltage.

[0075] It can be understood that since the method embodiment and the device embodiment are different presentation forms of the same technical concept, the content of the method embodiment part in this application should be synchronously adapted to the device embodiment part and will not be repeated here.

[0076] In the case of an integrated unit, such as Figure 8 As shown, Figure 8 is a structural block diagram of another control device for a DC-DC converter provided in an embodiment of the present application. Figure 8 In the embodiment, the control device 70 of the DC-DC converter includes: a processing module 72 and a communication module 71. The processing module 72 is used to control and manage the actions of the control device of the DC-DC converter, for example, to execute the steps of the acquisition unit 701, the judgment unit 702 and the switching unit 703, and / or to execute other processes of the technology described herein. The communication module 71 is used to support the interaction between the control device of the DC-DC converter and other devices. Figure 8 As shown, the control device of the DC-DC converter may further include a storage module 73, and the storage module 73 is used to store program codes and data of the control device of the DC-DC converter.

[0077] All relevant contents of each scenario involved in the above method embodiment can be referred to the functional description of the corresponding functional module, which will not be repeated here. Figure 2 The control method of the DC-DC converter is shown.

[0078] See also Fig. 9 , Fig. 9 is a structural block diagram of a DC-DC converter provided in an embodiment of the present application. Fig. 9 As shown, the DC-DC converter 11 includes a controller 90, and the controller 90 may include one or more of the following components: a processor 901, and a memory 902 coupled to the processor 901, wherein the memory 902 may store one or more computer programs, and the one or more computer programs may be configured to implement the method described in the above embodiment when executed by one or more processors 901. Specifically, the controller 90 may be implemented as an MCU (Microcontroller Unit).

[0079] It can be understood that the DC-DC converter may include more or fewer structural elements than those in the above structural block diagram, which is not limited here.

[0080] An embodiment of the present application also provides a computer storage medium, on which a computer program / instruction is stored. When the computer program / instruction is executed by a processor, part or all of the steps of any method recorded in the above method embodiments are implemented.

[0081] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0082] In the several embodiments provided in the present application, it should be understood that the disclosed methods and devices can be implemented in other ways. For example, the device embodiments described above are merely schematic; for example, the division of the units is only a logical function division, and there may be other division methods in actual implementation; for example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0083] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0084] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may be physically included separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0085] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions without departing from the spirit and scope of the present invention, and can make various changes and modifications, including the combination of the above-mentioned different functions and implementation steps, including software and hardware implementation methods, all of which are within the scope of protection of the present invention.

Claims

1. A control method for a DC-DC converter, characterized in that: A DC-DC converter applied to a DC bus power supply system, the DC bus power supply system comprising a plurality of DC-DC converters, a plurality of battery packs and a DC load, the plurality of DC-DC converters and the plurality of battery packs being connected in a one-to-one correspondence, each DC-DC converter being connected to the DC load via a DC bus, the method comprising: Get the DC bus voltage; If the DC bus voltage is greater than the first preset voltage, it is determined whether a first preset condition is met, wherein the first preset condition refers to that the battery group in the same group corresponding to the DC-DC converter has a charging demand, and the working modes of other DC-DC converters are all hot backup modes, and the working modes include the hot backup mode, the charging mode and the discharging mode. The hot backup mode refers to a working mode in which the MOS tube of the DC-DC converter remains in a normally off state, the charging mode refers to a working mode in which the MOS tube of the DC-DC converter remains in a normally on state so that energy flows to the battery group in the same group, and the discharging mode refers to a working mode in which the MOS tube of the DC-DC converter remains in a normally on state so that energy flows to the DC bus; If it meets the requirements, the operating mode is switched to the charging mode; If not, the operating mode is switched to the hot standby mode.

2. The method according to claim 1, characterized in that Before determining whether the first preset condition is met, the method further includes: The set voltage on the DC bus side of the DC-DC converter is adjusted to the first preset voltage, so that the DC-DC converter can increase the energy transfer efficiency when the DC bus voltage is less than the first preset voltage.

3. The method according to claim 2, characterized in that After obtaining the DC bus voltage, the method further includes: If the DC bus voltage is less than or equal to the first preset voltage, determining whether a discharging prohibition instruction of the same battery group is received; If yes, switch its own working mode to the hot standby mode; If not, switching its own working mode to the discharge mode; Sending its own output power to a target DC-DC converter among the multiple DC-DC converters, so that the target DC-DC converter generates a plurality of control signals corresponding to the multiple DC-DC converters one by one according to the output power of each DC-DC converter; A target control signal is received from the target DC-DC converter, and its own working mode is switched according to the target control signal.

4. The method according to claim 3, characterized in that The switching of the working mode according to the target control signal includes: If the target control signal indicates discharge, switching its own working mode to the discharge mode; If the target control signal does not indicate discharge, adjusting the set voltage on the DC bus side of the DC-DC converter to a second preset voltage, and switching its own working mode to the hot backup mode; When the DC bus voltage is less than or equal to the second preset voltage, the operating mode is switched to the discharge mode.

5. The method according to claim 3 or 4, characterized in that: The step of sending the target DC-DC converter of the plurality of DC-DC converters its own output power so that the target DC-DC converter generates a plurality of control signals corresponding to the plurality of DC-DC converters one by one according to the output power of each DC-DC converter, comprising: Sending its own output power to a target DC-DC converter among the multiple DC-DC converters, so that the target DC-DC converter performs the following operations: Calculating the total output power according to the output power of each DC-DC converter; Calculating a minimum required quantity according to the total output power and the rated power of each DC-DC converter; Generate X first control signals and Y second control signals; wherein Y=NX, X is the minimum required number, N is the number of DC-DC converters in the DC bus power supply system, the first control signal indicates discharge, and the second control signal does not indicate discharge.

6. The method according to claim 5, characterized in that The rated power of each DC-DC converter is the same, and the minimum required number is calculated by the target DC-DC converter according to the total output power and the rated power of each DC-DC converter by the following formula: X=CEILING(P1 / P2); Wherein, CEILING() is a round-up function, P1 is the total output power, and P2 is the rated power of each DC-DC converter.

7. The method according to claim 6, characterized in that After generating X first control signals and Y second control signals, the target DC-DC converter further performs the following operations: Dividing the plurality of DC-DC converters into a first queue and a second queue, wherein the first queue includes X DC-DC converters and the second queue includes Y DC-DC converters; The following operations are performed for the first queue and the second queue: sending the first control signal to each DC-DC converter in the first queue; sending the second control signal to each DC-DC converter in the second queue; After a preset time period, move the first DC-DC converter in the first queue to the end of the second queue, and move the first DC-DC converter in the second queue to the end of the first queue, so as to update the first queue and the second queue; The above operation is repeatedly performed until the DC bus voltage is greater than the first preset voltage.

8. A control device for a DC-DC converter, characterized in that: A DC-DC converter used in a DC bus power supply system, the DC bus power supply system comprising a plurality of DC-DC converters, a plurality of battery packs and a DC load, the plurality of DC-DC converters and the plurality of battery packs being connected in a one-to-one correspondence, each DC-DC converter being connected to the DC load via a DC bus, the device comprising: An acquisition unit, used for acquiring a DC bus voltage; a judgment unit, configured to judge whether a first preset condition is met if the DC bus voltage is greater than a first preset voltage, wherein the first preset condition refers to that a battery group in the same group corresponding to the DC-DC converter has a charging demand, and the working modes of other DC-DC converters are all hot backup modes, wherein the working modes include the hot backup mode, the charging mode, and the discharging mode, wherein the hot backup mode refers to a working mode in which the MOS tube of the DC-DC converter remains in a normally off state, the charging mode refers to a working mode in which the MOS tube of the DC-DC converter remains in a normally on state so that energy flows to the battery group in the same group, and the discharging mode refers to a working mode in which the MOS tube of the DC-DC converter remains in a normally on state so that energy flows to the DC bus; A switching unit is used to switch its own working mode to the charging mode if the conditions are met; and to switch its own working mode to the hot backup mode if the conditions are not met.

9. A DC-DC converter, characterized in that: The method comprises a controller, wherein the controller comprises a processor, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the processor, and the program comprises instructions for executing the steps in the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program or instruction stored thereon, characterized in that: When the computer program or instruction is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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