DC voltage control and stability analysis of PWM-voltage-type reversible rectifiers

A pulsewidth modulation (PWM) voltage rectifier has useful characteristics on their de and ac sides, On its de side, a de-link unidirectional voltage is obtained and bidirectional power transfer capability is possible by reversing the flow direction of the de-link current. On its ac side, near sinusoidal current waveforms and ac four-quadrant operation can be obtained, leading to a high-quality power being exchanged between the converter and the mains. The use of ac filters becomes unnecessary. The rectifier de voltage must be regulated to a constant value. In this paper, three solutions for the de voltage control are presented. In the first solution, the de voltage is controlled by acting upon the quadrature component of the converter fundamental Park's voltages with relation to the mains voltages, Slow responses are necessary because of stability reasons. Also, load power variations produce both active and reactive power variations in the converter ac side. To improve the de voltage response, a second control solution is presented. The converter currents in Park's coordinates must be controlled. The dc voltage is controlled by controlling the direct Park's current component and, thus, acting only on the active power of the converter ac side. Faster responses are achieved. In this case, load power variations do not produce reactive power variations in the converter ac side, The third control solution is a simplified version of this last one. Experimental results from a 2-kVA insulated gate bipolar transistor (IGBT) prototype showing a good system dynamic performances are presented.