Research On High Power DC-DC Converter Series-Parallel Thchnology

In recent years, with the development of power electronics technology and the expanding range of applications of power electronic products, the demand of high-performance and high-reliability power converter in high-voltage and high-power application continues to increase. If a single DC-DC power converter be used, many issues need to face, such as high input and output current ripple, large voltage stresses and losses of the power devices, hige electromagnetic interference etc. Multiple converter modules connected with series or parallel at the input side and output side, can be a good solution to the above problems. The main advantages of the DC-DC series-parallel power conversion system include: low voltage and current stresses of the power devices; high reliability because of redundancy of system; standardized converter modules leading to reduction in developmenting time and cost; flexible combination leading to support varying input-output power level requirements etc.Firstly, this paper reveals the intrinsic link between four types, and detailly analyzes the stability of series-parallel power conversion system when use the control strategy about input side and output side sharing of voltages/currents. This paper chooses the ZVS full-bridge converter as the basic module, and fouses on the two power conversion sytems of input-series output-parallel (ISOP) and input-paralel output-series (IPOS). This paper derives the characteristics of systems with interleaving control, and detailly analyzes the influence of the un-sharing voltage and un-sharing current. This paper also derives the small-signal mathematical model and detailly designs their control system of the input-series output-parallel (ISOP) and input-paralel output-series (IPOS). Then this paper builds simulation models of IPOS and ISOP, the result fully verify the validity of theoretical analysis and the effectiveess of their control schemes.Finally, this paper concludes the characteristics and laws the about two power conversion sytems of IPOS and ISOP, the conclusions can be extended to other circuit topologies, such as forward, push-pull, half-bridge etc.