Digital proportional derivative control with steady-state error elimination for DC-DC switching converter

In this paper, a novel digital proportional derivative (D-PD) control algorithm combined with steady-state error elimination is proposed for digitally controlled DC-DC switching converters. The system steady-state error due to the absence of integral in D-PD is eliminated by a register-based error-shift technique without increasing hardware circuit scale. Compared with the digital proportional integral derivative (D-PID) control, proposed control algorithm has fast transient response speed and small overshoot, and also it is easily implemented by hardware circuit as compared with the fuzzy and non-linear control. The design method of voltage compensator in z-domain is given, and the experimental results based on FPGA are provided, which have verified the theoretical analysis results very well. It can be concluded that, the proposed D-PD control algorithm with steady-state error elimination has the advantages of better transient performances and easier hardware implementation simultaneously over the existed control algorithms, therefore it can be used for voltage feedback control in digitally controlled DC-DC switching converters.