Can variable frequency drive run in parallel?

It turns out that a 7.5KW frequency converter drives a 7.5KW belt motor. Due to technical reasons, the power of this 7.5KW motor needs to be increased to 15KW. The original frequency converter is no longer specified, and the power is too small! So, is there any good solution?

Some people will think whether the variable frequency drive can run in parallel like a transformer? That is, two 7.5KW variable speed drive are directly connected together to drive a 15KW load. So, can two inverters run in parallel? This seems to be the first problem to be solved.variable frequency drive

In principle, it is no problem to connect two vfd inverters in parallel, that is, the power terminals are connected in parallel, and the load terminals are connected in parallel. To achieve parallel operation of two frequency converters, the conditions are relatively harsh.

First of all, the control methods and switching frequencies of the two frequency converters must be completely consistent, and the waveforms of the output voltages must be completely consistent, including amplitude, frequency and initial phase, and the frequency change rate must also be the same. This requires precise control of the power unit. Furthermore, not only must the switching device meet the requirements in a steady state, but it must also be consistent during the dynamic adjustment process.

Therefore, it is quite difficult to realize the parallel connection operation of two vfd inverters. It is necessary to control the output voltage synchronously. It is neither economical nor easy to realize. Therefore, I personally feel that the realization is of little significance. , It is better to directly change to a 15KW variable speed drive.

In the field, it is common for one frequency drive to drive multiple motors, but it is unusual for two or more vfd inverters to drive one motor. For high-power frequency conversion, some brands use the parallel connection of unit modules, which is also very common, especially for low-voltage frequency conversion over 400KW, which basically adopts parallel connection. This and the above are two concepts. It can be understood that the former is two frequency converters, while the latter belongs to one frequency converter, which is composed of two or more unit modules connected in parallel.

For more information about variable speed drive, please contact us.