Improved transient performance of a 3-phase controlled rectifier using predictive control

A simple ride-through control strategy, referred to as open loop predictive control, is presented. First, a model is proposed for the commonly used three-phase controlled rectifier, and the corresponding circuit equations are derived, such that the transient response can be accurately predicted for a given sequence of firing angles and for given initial conditions. Next, an algorithm is presented which can be used in a simple computer program to generate the required sequence of firing angles that will bring the system from a given initial-state to the steady-state in the minimum time possible. Such firing angle sequences can be stored in ROM (read only memory) and then used by the controller of the rectifier to ride through short-term line disturbances. Simulation and experimental data are also presented