Installed Power of Transformers for Equivalent Multiphase Rectification Circuits

The article describes one of the most rational ways to improve the shape of the consumed current curve by semiconductor converters - the use of transformer converters of the number of phases, which make the current consumed by semiconductor converters closer to sinusoidal, reducing the adverse effect of such devices on the network. Rectifiers are considered as the most widely used semiconductor converters that are designed to supply DC consumers in the presence of an AC voltage network. Rectifiers can also serve as the first stage of a cascade for generating electrical energy, the parameters of which - (in general) frequency, number of phases, current form, differ from the standard parameters of the network. The considered transformers not only bring the current consumption closer to sinusoidal, but also reduce the amount of ripple of the rectified voltage. In this case, there is also a combination of a multi-phase rectifying system that provides a high degree of electromagnetic compatibility of the rectifier with the network and load, with the maximum possible use of rectifier cells and windings of multi-phase transformers. To confirm the effectiveness of the considered converters, a method was developed for calculating the installed power of transformer converters by the example of their joint operation with 12-, 18-, and 24-pulse rectifiers. Using the example of phase-converting transformers for various schemes of connecting the primary and secondary windings to power the 24-pulse converters, a more precise calculation of the installed power was made by determining the values of the magnetomotive forces of the windings. On the basis of the obtained analytical expressions, it is shown how the installed power of the considered transformers with the numbers of output phases that are multiples of three, starting from three and further with the subsequent increase, differs from the installed power of the three-phase rectifier transformer.