Patent ID: 7535738

Claim:
An apparatus for converting X phase intermediate voltages on X intermediate lines to output voltage for driving a single three phase load where X is a multiple of three, the apparatus comprising: a positive DC bus; a negative DC bus; a first three phase drive that includes a first three phase rectifier and a first three phase inverter, the first three phase rectifier linked to a first three of the X phase intermediate lines and to each of the positive and negative DC buses, the first three phase inverter linked to each of the positive and negative DC buses and to the single three phase load to provide voltage to the load, the first rectifier receiving three phase intermediate voltages via the first three intermediate lines and converting the intermediate voltages to DC bus voltage across the buses, the first inverter converting at least a portion of the DC bus voltage to AC voltage and providing the AC voltage to the single three phase load; and a second three phase drive that includes a second three phase rectifier and a second three phase inverter, the second three phase rectifier linked to a second three of the X phase intermediate lines and to each of the positive and negative DC buses, the second three phase inverter linked to each of the positive and negative DC buses and to the single three phase load to provide voltage to the load, the second rectifier receiving three phase intermediate voltages via the second three intermediate lines and converting the input voltages to DC bus voltage across the buses, the second inverter converting at least a portion of the DC bus voltage to AC voltage and providing the AC voltage to the single three phase load; wherein a controller receives three phase modulating waveforms and uses those waveforms to drive the drives, the controller reducing the waveform magnitudes prior to using the waveforms to control the drives.