A digitally controlled switch mode power supply based on matrix converter

High power telecommunication power supply systems consist of a 3-phase switch mode rectifier followed by a DC-DC converter to supply loads at -48 V DC. These rectifiers draw significant harmonic currents from the utility, resulting in poor input power factor with high total harmonic distortion (THD). In this paper, a digitally controlled 3-phase switch mode power supply based on a matrix converter is proposed for telecommunication applications. In the proposed approach, the matrix converter directly converts the low frequency (50/60 Hz, 3-phase) input to a high frequency (10/20 kHz, 1-phase) AC output without a DC-link. The output of the matrix converter is then processed via a high frequency isolation transformer to produce -48 V DC. Digital control of the system ensures that the output voltage is regulated and the input currents are of high quality under varying load conditions. Due to the absence of DC-link electrolytic capacitors, power density of the proposed rectifier is expected to be higher. Analysis, design examples and experimental results are presented from a 3-phase 208 V, 1.5 kW laboratory prototype converter.