A three-phase pulse width controlled semiconverter

The authors present a novel three-phase pulse-width-controlled semiconverter topology, using a novel PWM (pulse-width modulation) control strategy in order to reduce the low-order harmonic content in both the input current and the output voltage. The circuit operates with unity displacement factor at its input and uses minimum power components. The proposed PWM strategy allows its implementation on a three-phase semiconverter bridge with only three controlled switches, so as to obtain PWM controlled rectification. Although the circuit operation is explained with force commutated SCR switches, the basic controlled PWM operation is valid for any alternative controlled switches, such as GTO or transistors, which do not require the commutating power components. The circuit has wide applications ranging from rectifiers and battery chargers to motor drives