An Inductor Current Observer Based on Improved EKF for DC/DC Converter

In order to reduce the voltage noise caused by Electromagnetic Interference (EMI), and eliminate the steady state error caused by load changes, a inductor current observer based on an improved Extended Kalman Filter (EKF) has been proposed. First, the current observer and EKF are introduced, and then the improved EKF with load estimation algorithm is proposed. The actual load can be estimated according to the output voltage of the improved EKF, the inductor current and the PWM duty ratio. Thereby the EKF parameters can be updated in real time, so that the inductor current can be accurately estimated by the current observer. Finally, the proposed current observer is verified by experiment. When the load disturbance happens, the experimental results show that the improved EKF can efficiently filter out the output voltage noise caused by EMI and guarantee the DC/DC converter output voltage accuracy.