A fundamental verification of a single-phase to three-phase matrix converter with a PDM control based on space vector modulation

This paper discusses pulse density modulation (PDM) control methods for a single-phase to three-phase matrix converter for high-frequency applications such as the grid interface converter for a wireless power transfer system and high-frequency transformer link system. The input frequency for this converter is assumed as several hundred kHz, and at the same time outputting a commercial frequency, i.e. 50 Hz or 60 Hz. The proposed circuit achieves high efficiency by zero voltage switching from a PDM control method. In the PDM control using delta-sigma conversion, the output waveform has inverse voltage pulse and clamp phenomena on the output voltage waveform. Hence, an improvement method of the output waveform based on SVM is proposed. In this paper, the experimental results using the prototype circuit of indirect matrix converter (IMC) and conventional matrix converter (CMC) with the two PDM control methods are compared. As a result, the THD of the output voltage with delta-sigma conversion and PDM pattern method based on SVM are 5.96% and 2.15% respectively in the experiment using IMC. Furthermore, the maximum efficiency has been improved from 93.4% to 97.3% by applying the proposed PDM method. From the results, the validity of PDM control based on SVM has been confirmed. In addition, a prototype of direct type circuit (CMC) has been built and tested. From the results, the switching at zero voltage and clear sinusoidal output waveform has been confirmed too. As a result, the output voltage THD, which is controlled by the proposed PDM based on SVM are 3.25%.