Generation of two three-phase PWM signals for matrix inverter

摘要

Conventional three-phase modulation signals are weighted by means of upper and lower correction factors (Ko,Ku) which depend upon an ascertained network voltage angle (gamma N) and actual network voltage values (uNR,uNS,uNT). A partial system simulator (24) is used with a correction factor generator (26) and upper and lower multipliers (28,30). To form the correction factors, two co-ordinate transformers (38,40) produce Cartesian and polar co-ordinates representing the network voltage modulus and angle. The corrections (Uo,Uu) are ordered (34) and multiplied (44,6) by the reciprocal (50) of a factor (UD) corresp. to the partial intermediate circuit voltage in a three-point invertor, with sign reversal (48) for the upper correction factor (Ko).