Online monitoring modulation strategy of three-level NPC inverter

Abstract

The invention discloses an online monitoring modulation strategy of a three-level NPC inverter, and belongs to the field of inverter control. According to the on-line monitoring modulation strategy, the on-line monitoring process can be manually adjusted according to the operation condition of a to-be-monitored inverter, the monitoring starting moment and the monitoring duration are controllable, and the unicity of an existing on-line monitoring method is overcome. Besides, the on-line monitoring modulation strategy provided by the invention does not have any influence on the load current electric energy quality of the to-be-monitored inverter, so that the to-be-monitored inverter can be monitored at any time when the inverter works on line. The strategy is simple in principle and convenient to implement.

Description

Technical field: [0001] The invention relates to a modulation strategy of a three-level NPC inverter, in particular to a modulation wave reconstruction strategy during online monitoring of a three-level NPC inverter, and belongs to the field of inverter control. Background technique: [0002] Compared with the two-level inverter, the three-level inverter has the advantages of small output voltage and current harmonics, and the voltage and switching loss of the switching device are halved, which can effectively reduce the size and size of passive components such as filters. weight. Therefore, three-level NPC inverters have gradually moved from high-power medium-voltage applications to low-voltage photovoltaic, wind power and energy storage grid-connected inverter systems. However, with the increase in the number of switching devices and the increase in system power, the reliability of the inverter system is facing challenges. IGBT has the advantages of fast switching speed,...

AI Technical Summary

Problems solved by technology

[0007] 1) The adaptability of the monitoring method and the system under test is not considered;

[0008] 2) The existing online monitoring modulation strategy can only find a certain monitoring start time, so that the monitoring has the least impact on the normal operation of the inverter, but it cannot completely eliminate the impact;

[0009] 3) The monitoring duration in the existing online monitoring modulation strategy is a fixed value determined artificially, which cannot be determined according to the operating status of the inverter, and the monitoring strategy is not optional

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