Iļja Galkins

Accuracy considerations for single-phase digital derivative based AC-grid synchronization unit

Accurate grid synchronization unit is essential for reliable operation of grid converters. Single-phase unit may utilize measured function and its digital derivative as the base for PLL. This paper compares some solutions of accuracy problems typical for such derivative approach: oversampling of measurements, interleaved calculation of derivative and averaged evaluation pulse signals. The proposed methods are described and implemented with a low cost microcontroller. Resulting declinations of space vector and calculated phase angle are compared. It is concluded that all the described methods provide certain accuracy improvement, but measurements in interleaved series are the most accurate method. It is also concluded that the overall evaluation of these methods must include analysis of the hardware and software resources spent for their implementation that requires an extra work.

Development of a Modular Power Converter

Development of a Modular Power Converter This report describes the most important details of elaboration of a versatile power module that can be utilized as a part of various converters. Two or more modules connected together can form a frequency converter or multilevel converter or 3-phase inverter/rectifier etc. Initially the module was developed for fast prototyping of uninterruptible power supplies and energy systems with alternative energy sources. The module can be used also as a basis for laboratory equipment of the power electronics course.