A novel concept for mains voltage proportional input current shaping of a VIENNA rectifier eliminating controller multipliers. II. Operation for heavily unbalanced mains phase voltages and in wide input voltage range

For pt. I see ibid., p.582-6 (2001). Part II shows the operation of a three phase PWM (VIENNA) rectifier operating with symmetric and heavily unbalanced mains voltage for application of a conventional phase current control and for the novel multiplier free current control concept. Taking into consideration the additional parts which are required in equal form for both concepts (input current measurement, output voltage measurement and control, supervisory functions and microcontroller), the saving in board space will be, however, only in the range of about 10%. A further advantage of the multiplier free control concept is that no information about the sign or magnitude of the input phase voltages is required for performing the control function. Furthermore, in contrast to the conventional control concept there is no requirement of an adjustment of the amplitude of the triangular shaped carrier signal and of the amplitude of rectangular shaped pre-control signal to the rectifier voltage transfer ratio. This would be especially advantageous for applications where the output voltage level is considered as a degree of freedom for maximizing the efficiency of the rectifier in combination with a DC-to-DC converter connected in series at the output. A drawback of the multiplier free control concept is the requirement of generating two unipolar triangular shaped carrier signals with adjustable amplitude and high accuracy