Advanced digital control strategies for power DC/DC converters

A DC/DC converter is used in some AC traction drives to improve the transient behavior and to hold the output voltage at the prefixed value. This converter is realized by inserting a conventional chopper between two power filters, the first one connected to the contact line, the second one to the inverter. The dynamic behavior of the chopper is highly influenced by these filters. The control of the inverter voltage is effected by applying a PWM (pulse width modulation) technique. The procedure for designing the control strategy is illustrated for a step-up converter. The general model is first deduced and the static characteristics are computed. The linearized model is then obtained and a simplified model is proposed. The control strategy is worked out so as to satisfy different requirements in the input-output behavior and in the disturbance-output behavior