Parallel current sharing method for power electronic converter

Abstract

The invention discloses a power electronic converter parallel current sharing method, and belongs to the technical field of converter control. The method comprises the steps that a power electronic converter composed of Vienna-LLC serves as a single module, and the cascading condition of a circuit and the number of modules connected in parallel are determined according to input and output voltage levels and power levels; judging and selecting a current sharing control scheme according to the magnitude of the output current to realize current sharing; and the system is operated, and when the output load is continuously changed, the system also continuously judges the magnitude of the output current so as to update the current sharing control and maintain rapid current sharing. According to the method, the stable speed of the converter can be improved, and the method has great engineering application value and popularization prospect.

Description

Technical Field

[0001] The invention relates to the field of converter control, in particular to a current balancing method for parallel connection of power electronic converters. Background Art

[0002] With the development of power electronics technology, DC switching power supplies are gaining more and more attention. The main function of power electronic converters is to convert input electrical energy into required output electrical energy, and to maintain good conversion efficiency and system stability. However, due to the continuous increase in the capacity of various power-consuming equipment, the output power of a single power module has been difficult to meet the needs of high-power loads. Therefore, multiple power modules working in parallel have become a common way to improve power output and system reliability. However, when multiple converters work in parallel, due to factors such as manufacturing differences, working environment, and load characteristics, the load current distribution between the converters is often uneven, which may cause some converters to be overloaded, overloaded, or even fail, while other converters may be lightly loaded or unloaded.

[0003] In order to solve the above problems, current sharing technology came into being. It has become the key to the development of switching power supplies towards large capacity. Its essence is to feed back the module's own current to the control system, and adjust the output voltage after comprehensive processing to change the current. In existing technologies, a variety of control methods have been proposed for the current sharing problem of parallel converters. However, in actual applications, these solutions are difficult to achieve timely response and stability of the system in scenarios with large dynamic changes in loads. Therefore, how to accurately control the current distribution between each converter is still facing challenges. Summary of the invention

[0004] As described above, a method for current sharing of power electronic converters in parallel is provided, the method comprising:

[0005] The power electronic converter composed of Vienna-LLC is used as a single module. The cascade status of the circuit and the number of modules in parallel are determined according to the input and output voltage levels and power levels. The current sharing control scheme is selected according to the output current size to achieve current sharing. When the system is running, when the output load is constantly changing, the system will also continuously judge the output current size to update the current sharing control and maintain fast current sharing.

[0006] Optionally, the current balancing control includes a maximum current balancing method and a droop control method.

[0007] Optionally, the current magnitude selection threshold is determined by current sharing accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a flow chart of the current sharing method of parallel connection of power electronic converters;

[0009] Figure 2 This is the parallel circuit diagram of Vienna-LLC modules;

[0010] Figure 3 This is a schematic diagram of the output impedance method;

[0011] Figure 4 Schematic diagram of the maximum current balancing method. DETAILED DESCRIPTION

[0012] Now, exemplary embodiments of the present invention are described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention. In the accompanying drawings, the same units / elements are marked with the same reference numerals.

[0013] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0014] The power electronic converter composed of Vienna-LLC is used as a single module. The cascade status of the circuit and the number of modules in parallel are determined according to the input and output voltage levels and power levels. The current sharing control scheme is selected according to the output current size to achieve current sharing. When the system is running, when the output load is constantly changing, the system will also continuously judge the output current size to update the current sharing control and maintain fast current sharing.

[0015] The current sharing control includes a maximum current sharing method and a droop control method.

[0016] The current magnitude selection threshold is determined by the current sharing accuracy.

[0017] The present invention will be further described below in conjunction with embodiments:

[0018] The process flow chart of the present invention is as follows: Figure 1 As shown, including:

[0019] S1. The single module used is as follows Figure 2 As shown, according to the given voltage level and power level, the series and parallel connection of the output end LLC and the parallel connection number of the entire module are determined respectively.

[0020] S2. After forming the model, confirm the current switching threshold according to the current sharing accuracy requirements

[0021] S3. Select the corresponding current sharing control scheme according to the current size, such as Figure 3 , Figure 4 The maximum current equalization method or droop control method.

[0022] S4. The current size caused by the circuit load change will re-judge and select the current sharing control scheme to achieve fast current sharing.

[0023] The present invention proposes a current-sharing method for parallel connection of power electronic converters, which greatly saves manpower, helps to improve the operating stability of the converter, and has great engineering application value and promotion prospects.

[0024] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The scheme in the embodiments of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0025] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that specifies the functions of a block or multiple blocks

[0026] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide for implementing the process in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0027] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application. Obviously, those skilled in the art may make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A method for current balancing of power electronic converters in parallel, the method comprising: The power electronic converter composed of Vienna-LLC is used as a single module. The cascade status of the circuit and the number of modules in parallel are determined according to the input and output voltage levels and power levels. The current sharing control scheme is selected according to the output current size to achieve current sharing. When the system is running, when the output load is constantly changing, the system will also continuously judge the output current size to update the current sharing control and maintain fast current sharing.

2. According to the method described in claim 1, the current balancing control includes maximum current balancing method and droop control method.

3. According to the method described in claim 1, the current size selection threshold is determined by the current sharing accuracy.

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