Research On The Current Share And Interleaving Control Of The Paralleled DC/DC Converters

Compared with traditional single large power supply, the paralleled power systems have many obvious advantages. Due to their advantages in reliability, maintainability, flexibility and standardization, such systems have been proposed in many applications. Furthermore, if the cells paralleled in the system can be operated in an interleaving state, the input and output ripple amplitude will be decreased in a large degree with the rising of the ripple frequency.And then the quality of output voltage as well as current will be improved.Current share and interleaving control of the paralleled DC/DC converters are researched in this thesis. A kind of current share and automatic interleaving approach is proposed. In this new approach, distributed control circuits are adopted. Compared with the those existing approaches, the biggest characteristic of this approach is that, no other line between the cells is needed except the output bus, so that the system possesses high stability, and the "modularization" can be really realized.The principle of current share approach without current share line is introduced in detail, and the block diagram of the circuit is presented. In each cell, a high frequency signal is injected into the output bus to transfer the output current information of the cell, so that the current information of other cells can be known by detecting the high frequency signals in the output bus. Hence, the current reference of each cell can be regulated to realize the current share of the system. Research on automatic interleaving without interleaving bus is the main part of this thesis. The principle of the approach is described in detail. Simulations and circuit implementations are also presented. In this approach, the voltage pulses ridden on the output voltage are detected, through which the clock informations of other cells can be known. The switching signal phase of each cell is adjusted according to the switching sequences of other cells. 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. 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.