Recommendations and Typical Errors on Usage of Wirewound Resistors in Design of Power Converters

The wirewound resistors (WRs) are one of the most popular passive components in modern power converters. They are used for many purposes, including sensing, current limitation, discharging, and braking, therefore, depending on their main target, they are constructed prioritizing one of its characteristics. At the same time, one of the specifics of WR is significant parasitic reactance, which must be taken into account. This feature significantly impacts the operation of power converters, therefore, all side effects have to be carefully analyzed and countermeasures have to be implemented. In order to eliminate gap in this area, the authors provide a detailed insight into the design of various circuits with WRs in power converters and formalize the design process, highlighting 11 checkpoints. The authors share their 20-years experience in this field and illustrate five the most popular mistakes with oscillograms, which simplifies the misstep localization. It saves at least one iteration of prototyping and saves significant resources. This article is mainly addressed to young researchers, however, it could also be useful for experienced engineers without solid background in design with WRs.