Improvement of predictive current control performance using online parameter estimation in phase controlled rectifier

In a phase controlled rectifier, the fastest response can be achieved by predictive current control without any overshoot. However, any error in the load parameters can cause steady state errors between a reference current and the feedback current because this current control scheme depends on the mathematical relationships between the output current, the firing angle, and the power source voltage. Thus, in the predictive current control, an accurate parameter is necessary for attaining a zero steady-state error. In this paper, the load resistance and inductance are estimated using the least square method of an online parameter calculation based on digitally sampled instantaneous voltage and currents. For the careful sampling of data and the reduction of the calculation time, a new timer-based gating algorithm is proposed and explained in detail. Using the proposed algorithm, the fastest current control performance in the transient state is obtained by the online correction of load parameters in various simulations and experimental results.