摘要:
Method for controlling the dc-voltage balance at a neutral point clamped multi level inverter (100). The inverter is space vecotr controlled with a selective harmonic elimination modulation. Some vectors can be achieved by different switching patterns, resulting in different current direction at the neutral point (0). The respective switching patterns are choosen to control the voltage level at the neutral point.
摘要:
Multilevel power converting apparatus comprising an AFE rectifier (9), an inverter (5), a plurality of capacitors (C 1 , C 2 , C 3 , C 4 ) connected in series forming a capacitor bank (6) as a DC voltage bus arranged between the rectifier (9) and the inverter (5), and a controller adapted for determining if there is an imbalance in the intermediate nodes (of, O 2 , O 3 ). The controller increases the reactive power consumption of the rectifier (9) when they detect an imbalance in order to eliminate or reduce it, and the apparatus (100) comprises compensation means (7) for maintaining the power factor on the alternating-current system (101) as close as possible to the unit, which are arranged in parallel with the alternating-current system (101) and connected to the rectifier (9) and which comprise a behavior opposed to that of the rectifier (9) with respect to the reactive power consumption.