Design Considerations and Simulations of Parallel Operation of Six Pulse Converter using Interphase Transformer

High current thyristorized AC-DC multi-pulse converters have several industrial and research applications e.g. electroplating, heating, charging coil of electromagnet, electrolysis process, etc. The output DC current handled by these converters is of the order of several kA at comparatively lower voltages and hence parallel operation of these converters is essential for meeting the particular load current demand. The paper deals with identical multi-pulse rectifiers, implemented for AC to DC power conversion connected in parallel across the typical simulated load. Appropriate converter configuration has been selected in which phase displacement in their incoming AC supply voltages is used to increase the output pulse number. An inter-rectifier reactor, often known as an Inter-phase Transformer has been designed and paralleling of converters have been performed through inter phase transformer on the DC side which helps in symmetrical current sharing amongst paralleled rectifiers preventing circulating current between the rectifiers as well as allow them to operate independently in isolated manner. The paper presents design considerations including simulation of high current six pulse thyristorized converter and highlight the comprehensive and comparative analysis of interactions between two six pulse full wave bridge converter operating with and without inter phase transformer.