Research On Current-sharing And Interleaving Control Of Parallel DC Power Supply System

Compared with traditional single large power supply, the paralleled power systems have many obvious advantages,such as high power, high efficiency, high reliability and so on. However,in practical applications, small power module directly connected to the load power supply will bring many problems such as: the current imbalance between modules, the system output current ripple amplitude is too large and so on.This thesis is devoted to the research on the current sharing and interleaving control of paralleled DC power supply systems and proposes an improved approach of automatic current share and a kind of automatic interleaving control method. The improved scheme is added to the fault cell elimination mechanism, which makes the fault tolerance capability of the original current sharing control method greatly enhanced; the interleaved control method can realize the automatic interleaving as well as the interleaved operation of paralleled ripple clock, to further reduce the output ripple.The principle of the automatic current share control is analyzed in detail, and the realization process of the fault cell elimination is introduced in the paper. The average current signal of the adjacent cell is compared with the current cell to get the average current error signal to adjust the reference voltage setting value,and the duty cycle of the drive signal is adjusted according to the correction value. Adding fault cell exclusion mechanism to the control circuit can change the connection mode of signal lines to achieve the elimination of the fault cell.In this paper, the working principle of the automatic interleaving control method is described in detail, and a detailed comparison of ripple suppression ability is made between the ripple clock interleaved operation and the traditional staggered operation state. In this scheme, each cell can get the ripple clock signal by comparing the output current with the DC component, and then adjust the phase of the switching signal. If the cell number changes, the system can enter new state of interleaving operation automatically, so that automatic interleaving can be realized in this approach.After that,according to the proposed automatic current share control and interleaving control, the simulation model is built in the simulation software, and the simulation circuit is designed to implement the two control methods.Finally,a prototype which consists of three paralleled DC/DC converters is designed and developed. Some experiments have been made. The experimental results show that the approach proposed is feasible.