Three-level DC / DC fault isolation method

Abstract

The invention relates to the technical field of power electronics, in particular to a three-level DC / DC fault isolation method, which comprises a three-level DC / DC parallel system, and the three-level DC / DC parallel system comprises a plurality of groups of DC / DC units; the IGBT modules are used for balancing voltage fluctuation, the series modules are used for balancing short-circuit wires, and the isolation modules, the IGBT modules and the series modules are installed on the input sides and the output sides of the corresponding sets of DC / DC units. According to the three-level DC / DC fault isolation method, when short wiring occurs through a series module, fuses at the input ends of a plurality of DC / DC modules in work are fused, a small number of fuses at the input ends are fused, the input ends of the DC / DC modules are disconnected, and an electronic switch starts a connecting line containing a resistance wire to connect the DC / DC modules in series from the output ends; the short-circuit connection is blocked, so that the DC / DC module performs small-range circuit isolation and replacement when encountering a short circuit with small risk performance and continues to work after replacement is completed, the isolation action is reduced, and the isolation cost is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to a three-level DC / DC fault isolation method. Background Art

[0002] Three-level DC / DC belongs to the parallel technology of power electronic converters, which can reduce voltage fluctuations and effectively improve the reliability of the system. It is widely used in photovoltaics, UPS, fuel cells and other fields. Three-level DC / DC is a multi-parallel system. In order to improve the stability of three-level DC / DC, an isolation system is required to reduce risks and improve fault tolerance.

[0003] At present, the three-level DC / DC fault isolation method is used. Due to the complexity of the working environment, circuit short circuits are divided into many situations. Some short circuits are caused by line short circuits. The short circuit part can be fused and then reconnected to continue working. The direct isolation method is too costly and increases production costs. Summary of the invention

[0004] The purpose of the present invention is to provide a three-level DC / DC fault isolation method to solve the problem raised in the above background technology that due to the complexity of the working environment, there are many types of circuit short circuits. Some short circuits are caused by line short circuits, and the short circuit part can be fused and then connected to continue working. The direct isolation method is too expensive and increases the production cost. To achieve the above purpose, the present invention provides the following technical solutions: A three-level DC / DC fault isolation method, including a three-level DC / DC parallel system, wherein the three-level DC / DC parallel system includes multiple groups of DC / DC units;

[0005] A plurality of isolation modules, and a plurality of IGBT modules for balancing voltage fluctuations and series modules for balancing short-circuit wires, wherein the isolation modules, IGBT modules and series modules are installed at the input side and the output side of the corresponding group of DC / DC units;

[0006] It comprises an energy supply unit and a load, wherein the energy supply unit is connected to the output end of the three-level DC / DC parallel system;

[0007] When any of the DC / DC units is short-circuited, all the series modules are connected in a balanced manner, and the connection line in the fault group is disconnected from the three-level DC / DC parallel system. When the fault has a large impact, all the isolation modules are driven to block, and the DC / DC unit with the fault is disconnected from the three-level DC / DC parallel system.

[0008] In this process, the energy supply unit supplies energy to the load connected to the output end of the three-level DC / DC parallel system;

[0009] When the faulty DC / DC unit is isolated, the remaining DC / DC units are unblocked and resume supplying energy to the load. This three-level DC / DC fault isolation method uses the IGBT module to connect the four parts S1-S4 complementaryly, and stops the flow of current separately. For example, S1 only allows output, S4 only allows input, and S2 and S3 stop the flow. Then the voltage flows back from high to low to reach the voltage of 1, which is the definition value of normal operation. If S1 only allows output, S3 only allows input, and S2 and S4 are closed, then the voltage can only reach half of the normal voltage, which is defined as the intermediate voltage. The voltage has a process from zero to a certain value from the input end to the output end. Excessive voltage fluctuations will damage electrical components. The addition of the intermediate voltage increases the buffering process, which is beneficial to protecting the circuit and improving stability and service life.

[0010] Further preferably, the series module includes a series unit; the series unit is connected to the input side of the DC / DC unit. The three-level DC / DC fault isolation method uses the series module. When a short circuit occurs, the input end fuses of several working DC / DC modules are blown, a small number of input end fuses are blown, the input end of the DC / DC module is disconnected, and the electronic switch starts the connection line containing the resistance wire to connect the DC / DC modules in series from the output end, blocking the short circuit connection so that the DC / DC module can perform a small-scale circuit isolation and replacement when encountering a short circuit with low risk performance and continue to work after the replacement is completed, which is conducive to reducing isolation action and saving isolation cost.

[0011] Further preferably, the series module includes a series unit, the series unit is connected to the output side of the DC / DC unit, the series unit is composed of a resistor, an electronic switch, a connecting line and a fuse. In this three-level DC / DC fault isolation method, when a short circuit occurs, the input end fuses of several working DC / DC modules are blown, a small number of input end fuses are blown, the input end of the DC / DC module is disconnected, and the electronic switch starts the connecting line containing the resistor to connect the DC / DC modules in series from the output end, blocking the short circuit connection so that the DC / DC module performs a small range of circuit isolation and replacement when encountering a short circuit with low risk performance and continues to work after the replacement is completed, which is conducive to reducing isolation action and saving isolation cost.

[0012] Further preferably, the isolation module includes an isolation unit; the isolation unit is connected to the input side of the DC / DC unit. The isolation module includes an isolation unit; the isolation unit is connected to the output side of the DC / DC unit. This three-level DC / DC fault isolation method uses the isolation module. When the short circuit is not caused by the short circuit, or when the short circuit problem still occurs after the series module adopts the rear circuit, the fuse or electronic switch closer to the input end will be blown, and the fuse or electronic switch closer to the output end will be blown. Several DC / DC modules in operation are risk isolated. At this time, the energy supply module is equivalent to the backup power supply directly supplying power to the load to prevent the equipment from Stop working to improve work efficiency, then connect the electronic switch through the connection point where the previously blown fuse is closer to the input or output end, and the spare DC / DC module starts working, while the previously isolated DC / DC module starts to troubleshoot the problem and repair the line. Due to the large parallel mode of three-level DC / DC, the problems caused by short circuit of wires are more serious, but the large parallel mode has obvious advantages for many industries, and this isolation method is needed for isolation and blocking. This method uses a high-cost redundant system to prevent circuit problems in parallel circuits and ensure uninterrupted operation of equipment, which ensures work efficiency, helps improve protection performance, reduces electrical risks and improves safety.

[0013] Further preferably, the isolation unit includes any one of a fuse, a contactor, an electronic switch and a diode and a resistance wire.

[0014] Further preferably, the three-level DC / DC parallel system is an N+n redundant system, wherein N represents the number of the DC / DC units in normal operation, and n represents the number of the DC / DC units in standby operation.

[0015] Further preferably, when the three-level DC / DC parallel system is working normally or only the series module is enabled, the energy supply unit is suitable for storing energy through the output end of the three-level DC / DC parallel system. This three-level DC / DC fault isolation method, through the isolation module, when the short circuit is not caused by the short circuit, or when the short circuit problem still occurs after the series module adopts the rear circuit, the fuse or electronic switch closer to the input end will be blown, and the fuse or electronic switch closer to the output end will be blown, and several DC / DC modules in operation will be risk isolated. At this time, the energy supply module is equivalent to a backup power supply that directly supplies power to the load, preventing the equipment from stopping working and improving work efficiency.

[0016] Further preferably, the energy supply unit includes a battery pack or a supercapacitor pack, and is connected to the load end. When the three-level DC / DC parallel system stops operating, the energy supply unit is suitable for supplying power to the load end. This three-level DC / DC fault isolation method uses an isolation module. When the short circuit is not caused by a short circuit, or when a short circuit problem still occurs after the series module adopts a rear circuit, a fuse or electronic switch closer to the input end will be blown, and a fuse or electronic switch closer to the output end will be blown. Several DC / DC modules in operation are risk isolated. At this time, the energy supply module is equivalent to a backup power supply that directly supplies power to the load, preventing the equipment from stopping working and improving work efficiency. Then the backup DC / DC module connects the electronic switch through the connection point position of the previously blown fuse closer to the input or output end, and the backup DC / DC module works, while the previously isolated DC / DC module starts to troubleshoot the problem and repair the line. Complex, because the three-level DC / DC is in large parallel mode, the problems caused by short circuit of wires are more serious, but the large parallel mode has obvious advantages for the work of many industries, and this isolation method is needed for isolation and blocking. This method adopts a high-cost redundant system to prevent circuit problems in parallel circuits and ensure the uninterrupted operation of equipment, ensure work efficiency, help improve protection performance, reduce electrical risks, and improve safety. A series module is also added. When a short connection occurs, the input fuses of several working DC / DC modules are blown, a small number of input fuses are blown, the input end of the DC / DC module is disconnected, and the electronic switch starts the connection line containing the resistor wire from the output end to connect the DC / DC module in series, blocking the short circuit connection so that the DC / DC module can perform a small range of circuit isolation and replacement when encountering a short circuit with low risk performance and continue to work after the replacement is completed, which is conducive to reducing isolation action and saving isolation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of circuit analysis when the IGBT unit in the present invention does not fail;

[0018] Figure 2 Schematic diagram of circuit analysis when an IGBT unit fails in the present invention Figure 1 ;

[0019] Figure 3 Schematic diagram of circuit analysis when an IGBT unit fails in the present invention Figure 2 ;

[0020] Figure 4 Schematic diagram of circuit analysis when an IGBT unit fails in the present invention Figure 3 ;

[0021] Figure 5Schematic diagram of circuit analysis when an IGBT unit fails in the present invention Figure 4 ;

[0022] Figure 6 It is a structural schematic diagram of the series connection module in the present invention;

[0023] Figure 7 It is a structural schematic diagram of the isolation module in the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technical personnel in this field without creative work are within the scope of protection of the present invention.

[0025] See also Figure 1 - Figure 6 , the present invention provides a technical solution: a three-level DC / DC fault isolation method, comprising a three-level DC / DC parallel system, the three-level DC / DC parallel system comprising a plurality of groups of DC / DC units;

[0026] A plurality of isolation modules, and a plurality of IGBT modules for balancing voltage fluctuations and series modules for balancing short-circuit wiring, wherein the isolation modules, IGBT modules and series modules are installed on the input side and the output side of the corresponding group of DC / DC units;

[0027] It includes an energy supply unit and a load, and the energy supply unit is connected to the output end of the three-level DC / DC parallel system;

[0028] When any DC / DC unit is short-circuited, all series modules are connected in a balanced manner, and the connection line in the fault group is disconnected from the three-level DC / DC parallel system. When the fault impact is too large, all isolation modules are driven to block and disconnect the faulty DC / DC unit from the three-level DC / DC parallel system.

[0029] During this process, the energy supply unit supplies energy to the load connected to the output end of the three-level DC / DC parallel system;

[0030] When the faulty DC / DC unit is isolated, the remaining DC / DC units are unblocked and resume supplying energy to the load.

[0031] The series module includes a series unit; the series unit is connected to the input side of the DC / DC unit.

[0032] The series module includes a series unit, which is connected to the output side of the DC / DC unit. The series unit is composed of a resistance wire, an electronic switch, a connecting wire and a fuse.

[0033] The isolation module includes an isolation unit; the isolation unit is connected to the input side of the DC / DC unit. The isolation module includes an isolation unit; the isolation unit is connected to the output side of the DC / DC unit.

[0034] The isolation unit includes any one of a fuse, a contactor, an electronic switch, a diode, and a resistor.

[0035] The three-level DC / DC parallel system is an N+n redundant system, wherein N represents the number of DC / DC units in normal operation, and n represents the number of standby DC / DC units.

[0036] When the three-level DC / DC parallel system operates normally or only the series modules are enabled, the energy supply unit is suitable for storing energy through the output end of the three-level DC / DC parallel system.

[0037] The energy supply unit includes a battery pack or a super capacitor pack and is connected to the load end. When the three-level DC / DC parallel system stops operating, the energy supply unit is suitable for supplying power to the load end.

[0038] The above shows and describes the basic principles, main features and advantages of the present invention. Technical personnel in this industry should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not used to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A three-level DC / DC fault isolation method, characterized in that: It includes a three-level DC / DC parallel system, wherein the three-level DC / DC parallel system includes a plurality of groups of DC / DC units; A plurality of isolation modules, and a plurality of IGBT modules for balancing voltage fluctuations and series modules for balancing short-circuit wires, wherein the isolation modules, IGBT modules and series modules are installed at the input side and the output side of the corresponding group of DC / DC units; It comprises an energy supply unit and a load, wherein the energy supply unit is connected to the output end of the three-level DC / DC parallel system; When any of the DC / DC units is short-circuited, all the series modules are connected in a balanced manner, and the connection line in the fault group is disconnected from the three-level DC / DC parallel system. When the fault has a large impact, all the isolation modules are driven to block, and the DC / DC unit with the fault is disconnected from the three-level DC / DC parallel system. In this process, the energy supply unit supplies energy to the load connected to the output end of the three-level DC / DC parallel system; When the faulty DC / DC unit is isolated, the remaining DC / DC units are unblocked and resume supplying energy to the load.

2. A three-level DC / DC fault isolation method according to claim 1, characterized in that: The series module includes a series unit; the series unit is connected to the input side of the DC / DC unit.

3. A three-level DC / DC fault isolation method according to claim 2, characterized in that: The series module includes a series unit, which is connected to the output side of the DC / DC unit. The series unit is composed of a resistance wire, an electronic switch, a connecting wire and a fuse.

4. A three-level DC / DC fault isolation method according to claim 1, characterized in that: The isolation module includes an isolation unit; the isolation unit is connected to the input side of the DC / DC unit. The isolation module includes an isolation unit; the isolation unit is connected to the output side of the DC / DC unit.

5. A three-level DC / DC fault isolation method according to claim 2, characterized in that: The isolation unit includes any one of a fuse, a contactor, an electronic switch and a diode and a resistance wire.

6. A three-level DC / DC fault isolation method according to claim 1, characterized in that: The three-level DC / DC parallel system is an N+n redundant system, wherein N represents the number of the DC / DC units operating normally, and n represents the number of the DC / DC units in standby.

7. A three-level DC / DC fault isolation method according to claim 1, characterized in that: When the three-level DC / DC parallel system operates normally or only the series module is enabled, the energy supply unit is suitable for storing energy through the output end of the three-level DC / DC parallel system.

8. A three-level DC / DC fault isolation method according to claim 1, characterized in that: The energy supply unit includes a battery pack or a super capacitor pack and is connected to the load end. When the three-level DC / DC parallel system stops operating, the energy supply unit is suitable for supplying power to the load end.

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