Investigation of low cost control schemes for a selected 3-level switched mode rectifier

Two low-cost modulation schemes are presented for the control of a 3-level switched mode rectifier. One is based on a hysteresis controller and the other on a double ramp comparison. The latter control concept implemented by common PWM ICs yields preferable characteristics for the power interface to telecommunication equipment such as high power density, due to reduced volume for electromagnetic compatibility (EMC) and input current filtering, high control dynamics, low harmonic distortion (THD) and switching losses, which are comparable to those achieved by space vector control, but with less costs and complexity.