Dynamic control strategy for bi-directional DC/DC converters to suppress the dc-link voltage fluctuation in motor driver systems

Abstract

This paper presents an improved dc-link voltage control strategy for bi-directional DC/DC converter to reduce the fluctuation of dc-link voltage. The bi-directional DC/DC converter is the top widely-adopted topology for machine drives. However, a wild dc-link voltage fluctuation may cause the overvoltage accident if the load is suddenly altered. Therefore, a novel energy-balanced dc-link voltage control scheme is presented. Through the analysis of the instantaneous energy balance of the whole system, this paper draws a conclusion that the energy stored in the dc-link capacitor will fluctuate in the dynamic process. Then, when the output power changes, the influence of the proposed control strategy on the dc-link voltage fluctuation is analyzed. Moreover, some deadbeat predictive control method has been applied within the current inner loop to improve systematically dynamic response ability. As the energy consumption can be compensated, the fluctuation of dc-link voltage is constrained in sudden load change. Small-signal model has been presented to analyze dynamic performances. As a result, experimental outcomes verify that above method is equipped with superior dc-link voltage fluctuation suppression capability, and the current overshoot is reduced and dynamic performance is improved. What is more, the controller design is simple to realize and has a bright application prospect.

Keywords

• Bi-directional DC/DC converter
• Dc-link voltage control
• Fluctuation suppression
• Deadbeat predictive current control