Patent ID: 7471529
Filing Date: 2008-12-30
Classification: H02J,H02M,Y02B,Y02E,Y02P,Y10S

Abstract:
1. A method of modulating a three-phase three-level power converter comprising a first, a second and a third voltage source, each voltage source being configured to output a time-varying signal and being inductively coupled to a separate input node, each input node being connectable to a first output node, a second output node and a third output node, the converter further comprising a first capacitive element coupled between the first and the second output node and a second capacitive element coupled between the second output nodes and the third output node, wherein each time-varying voltage signal has substantially the same period and a different phase, the method comprising: determining which voltage signal has the highest voltage, the lowest voltage and the intermediate voltage higher than one of the voltage signals and lower than the other voltage signal for each of a plurality of sub-periods; determining which voltage signal is dominant for each of the plurality of sub-periods; connecting the voltage signal having the lowest voltage to only the third output node when the dominant voltage signal is lower than the non-dominant voltage signals; connecting the voltage signal having the highest voltage to one of the first output node and the second output node during each sub-period where the dominant voltage signal is lower than the non-dominant voltage signals; connecting the voltage signal having the intermediate voltage to one of the second output node and the third output node during each sub-period where the dominant voltage signal is lower than the non-dominant voltage signals; connecting the voltage signal having the highest voltage to only the second output node when the dominant voltage signal is higher than the non-dominant voltage signals; connecting the voltage signal having the lowest voltage to one of the first output node and the second output node during each sub-period where the dominant voltage signal is higher than the non-dominant voltage signals; and connecting the voltage signal having the intermediate voltage to one of the second output node and the third output node during each sub-period where the dominant voltage signal is higher than the non-dominant voltage signals.