US 7,589,984 B2
Method for starting pulse width modulation
Janne Salomäki, Hyvinkää (Finland)
Assigned to ABB OY, Helsinki (Finland)
Filed on Jan. 23, 2007, as Appl. No. 11/656,462.
Claims priority of application No. 06100694 (EP), filed on Jan. 23, 2006.
Prior Publication US 2008/0019157 A1, Jan. 24, 2008
Int. Cl. H02M 1/36 (2007.01)
U.S. Cl. 363—41 7 Claims
OG exemplary drawing
 
1. A method for starting the modulation of a frequency converter, which method comprises the steps of
receiving reference voltages, and
generating output switch commands from the reference voltages, wherein the generation of output switch commands comprises a step, in which the ratio of active time in a modulation period of selected zero vector and the total active time of zero vectors in a modulation period is changed from a first predetermined ratio, which is substantially 0 or substantially 1, to a second predetermined ratio, which is substantially 0.5.