Method and system for balance control over capacitance electric potential of three-phase four-level converter
A technology of potential balance and control method, which is applied in the direction of converting AC power input to DC power output, electrical components, and output power conversion devices, which can solve problems such as difficult implementation and complicated control process.
Active Publication Date: 2013-12-11
SUNGROW POWER SUPPLY CO LTD
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Problems solved by technology
[0004] Although there are many control strategies to solve the above-mentioned capacitive potential fluctuation problem in the prior art, there are generally disadvantages that the control process is complicated and difficult to implement.
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[0225]The following will clearly and completely describe the technical solutions in the embodiments of the application with reference to the drawings in the embodiments of the application. Apparently, the described embodiments are only some of the embodiments of the application, not all of them. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of this application.
[0226] The embodiment of the present application discloses a three-phase four-level converter capacitor potential balance control method and system, so as to simply and effectively realize the capacitor midpoint potential balance control of the three-phase four-level converter.
[0227] refer to figure 2 , the three-phase four-level converter capacitor potential balance control method provided in Embodiment 1 of the present application includes the following steps:
[0228] S101: Record th...
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The invention discloses a method and system for balance control over capacitance electric potential of a three-phase four-level converter. A bus voltage, capacitance neutral-point voltage offset and a three-phase current of the converter are detected and a reference level is calculated according to the bus voltage and a level coefficient. Meanwhile, three-phase voltage modulating order values are recorded and ranked and according to a ranking result and with the combination of the level coefficient, the reference level and the capacitance neutral-point voltage offset, a zero-sequence component is calculated. On the premise that a output level combination of each phase is not changed, the zero-sequence component is respectively added to the three-phase voltage modulating order values so that corrected three-phase output voltage modulating order values can be obtained, therefore the purpose of elimination of the capacitance neutral-point voltage offset is achieved and balance of the capacitance voltage is achieved. According to the method and system for balance control over the capacitance electric potential of the three-phase four-level converter, the zero-sequence component is determined through accurate calculation, the method is simple and easy to achieve, the accuracy of balance control over the capacitance voltage of the converter is improved, and an existing technical problem is solved.
Description
technical field [0001] The present application relates to the technical field of electric power control, in particular to a method and system for controlling capacitor potential balance of a three-phase four-level converter. Background technique [0002] In order to improve the inverter efficiency and grid-connected voltage level of photovoltaic inverters, more and more attention has been paid to multi-level topology technology. For multi-level inverters, due to the unbalanced output active power of the capacitors on the DC side of the multi-level topology, it is easy to cause the degradation of the number of levels; for this reason, the prior art proposes a series of DC side equipped with buck-boost devices multilevel inverter. [0003] Such as figure 1 A schematic structural diagram of an existing three-phase four-level converter system is shown. The DC source with a voltage of +2E only provides two levels of +E and -E in the four levels, and the other two levels are +(1...
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Inventor 邹海晏陶磊张建张明陈长春张玉
Owner SUNGROW POWER SUPPLY CO LTD