Deadbeat Control Based on New State-observer for PWM Rectifier

Inherent disadvantage of digital control is control time delay induced by the zero-order-hold effect and the computational time delay. It could induce system oscillation and even system stability could be destroyed. Predictive results of conventional current state observer were not ideal because that it was open loop in essence. To alleviate this problem, a method based on new state observer was proposed. The current state in a control period was described at first. The new output variable was acquired by sampling in the intermediate instant of control period and the observer error was corrected by it. The proposed method eliminates the time delay impact so that not only stability is increased but also deadbeat control is fully realized in current loop. A lab 1kW electronic load prototype with power regeneration ability was set up for the proof of concept. The prototype system was operated at 25 kHz switching frequency and was controlled by TMS320F2812 DSP. Experimental results verify the validity of the proposed scheme.