Improving the Reliability of Semiconductor Converters
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oving the Reliability of Semiconductor Converters M. E. Korzhavina, *, A. M. Zhuravlevb, and M. A. Grigoreva a
South Ural State University (National Research University), Chelyabinsk, 454080 Russia b OOO Rik-Energo, Shigaevo, 456510 Russia *e-mail: [email protected] Received May 8, 2020; revised May 18, 2020; accepted June 1, 2020
Abstract—This paper considers the opportunities for improving the reliability of power semiconductor converters by increasing the installed capacity margin and modifying the configuration of power circuit diagrams. As shown by regression analysis, the unit cost of an autonomous voltage inverter with an increase in the installed capacity of the frequency converter rises by about 25%. It is shown that the machine and the semiconductor converter are used most efficiently in six phases, whereas the number of valves in the semiconductor converter is 4m, where m is the number of phases. A further increase in the number of phases does not significantly reduce the phase current, but significantly increases the number of keys in the valve converter. It is shown that an increase in the phase of power circuit layouts allows using the electric machine more fully in terms of capacity and reduce the phase current in semiconductor converters by more than twofold. It is established that the new solutions allow reducing by almost twofold the number of failures in electric drives of more than 500 kW in capacity, while the costs of power electric equipment increase by no more than 25%. Keywords: semiconductor frequency converters, multiphase, reliability DOI: 10.3103/S1068371220070093
Modern electricity converters remain complex and expensive items for facilities in design. A facility’s general reliability is much dependent on the converter’s reliability; failures of equipment often have to do with failures of frequency converters. In most cases, the shutdown of a process facility conditioned by an electric equipment failure results in major economic losses; according to production process conditions, this shutdown is sometimes impermissible altogether. For data on the failure-free operation probability for certain process items and facilities, see Table 1. General-purpose industrial plants and facilities are known to have a failure-free operation probability of 0.8,
and this probability is exactly that of standard commercial frequency converters. The failure-free operation factor of general-purpose industrial plants and items is traditionally chosen proceeding from the need to minimize the aggregate costs of creating the equipment and maintain and repair it throughout its life cycle [1]. The reliability factor calculated against this criterion ranges from 0.5 to 0.85. It has recently become obviously necessary to refine the reliability factor by considering the damage from the idle period of the main plants and items in the process chain. In this case, the failure-free operation
Table 1. Failure-free operation probability factors Failure-free operation probability until complete overhaul,
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