Regarding two frequency converters driving one motor?

I’ve used quite a few frequency converters, but I’ve never seen this way of using them before; I’m very curious. Please advise. This post was last edited by chinahbzq on 2009-2-22 22:29]

I’ve never used it this way. Is it possible to upload technical documents so that I can learn*learn*?

It’s the original poster who’s imagining it! It’s not the case that two transformers can operate in parallel; as long as their parameters match, they can be used together. However, inverters are different, as their parameters keep changing constantly. If you have any clever solutions, please share them.

I’ve really never encountered it. Please, the original poster, provide a detailed explanation

Previous technologies were not up to par; it was difficult to manufacture high-power IGBTs. As a result, some companies used two or more inverters in combination when producing inverters, adding a synchronous triggering circuit as well as other related control boards. However, the performance of such systems was not very good, and their reliability was low, which is why they are rare in the market. Today’s IGBT modules are already quite large, so this approach is generally no longer used.

Finally, someone who has heard of this technology has shown up. Could LS provide more guidance on it? ? :lol

For high-power frequency converters, due to constraints such as the performance, cost, and manufacturing structure of electronic components, those in use in China at present rely mainly on imports. Moreover, the high cost of high-power frequency converters **limits their use in industrial production, thereby affecting progress in energy conservation and production automation. Therefore, it is of great importance to seek a cost-effective and easy-to-implement solution, and the inverter parallel connection approach can meet this requirement. Parallel connection of frequency converters offers the advantage of good cost-effectiveness, but it also presents certain issues (such as circulating currents, as well as problems with the detection of current, voltage, and temperature signals). If these issues are not properly addressed, it can lead to the system failing to operate properly. Therefore, well-designed detection and protection circuits are particularly important.

I’ve never used it this way. Is it possible to upload technical documents so that I can learn*learn*?

Yes, first of all, the parameters need to be consistent; it’s difficult to carry out comparisons, and it’s also hard to increase capacity. It’s hardly used these days

Why is it implemented this way? A 650kW motor isn’t considered large either; it can be operated in a one-to-one configuration using an appropriate frequency converter. If there are two small frequency converters available that could be put to use, then there is some room for consideration!

Theoretically, it is completely feasible; in practical use it isn’t very common. However, for controlling high-power motors, using two frequency converters to drive one motor is indeed a cost-saving solution.

SIEMENS and ABB have both released such frequency converters. It is designed to further improve the reliability and redundancy of the drive system, and allows for the online replacement of inverters.

I really have never heard of this approach. With the maturity of inverter technology today, large-capacity inverters can be manufactured very effectively; so what is the need to use two small inverters to drive one large motor? The detailed circumstances of specific cases should be provided for a detailed analysis.

Is what the poster is referring to the common DC bus application of frequency converters?

Could the original poster explain in more detail? Because the modules used in frequency conversion are also connected in series one after another, but they’re all paired up! ! ! If you do this with 2 inverters, where the parameters of the modules inside are not exactly the same, how can you drag them? If not handled properly, it could burn out the inverter! ! ! Then we’ll really set off firecrackers, hehe! ! !

After reading all the answers above, it seems that none of them involve large-scale drive systems. The setup mentioned by the original poster is used in the SIEMENS G120 series (low voltage), G150 (medium voltage), and ABB ACS800 (low voltage)； The ACS6000 (medium voltage) has this operating mode as well. What I do most often is use 4 2500KW frequency converters to drive a 9000KW synchronous motor! Those who are interested can download the relevant manuals to take a look.

I’ve never seen an inverter operate in this way. Could the original poster give more details? How does it work? ? ?

Low-voltage frequency converters are used this way so often because they are rarely manufactured with a capacity of over 600 KW; of course, low-voltage motors are also seldom used for capacities above 600 KW