Application of direct current control in control parallel pulses width modulation rectifiers

Along with the development of science and technology are the strict requirements for control quality and the capacity of the system. In recent years the use of the pulses width modulation (PWM) rectifier in control systems becomes more and more popular. In conventional control system, a small inverter is generally used to control the rectifier or power of the system, it therefore cannot satisfy the requirement of high performance and good quality control. A solution to this issue is the PWM rectifier control system that couples two or more inverters in parallel connection. The significant advantages of parallel inverter systems used in automatic control system are the capacity, reliability, flexibility and quality improvement and the ability of backing up the system. However, conducting parallel pair of PWM rectifier also exists many problems, such as the emergence of the equilibrium current circulation among the rectifiers, the existence of high harmonic components leads to unbalanced grid. Hence, a new suitable approach that could minimize the risks by optimizing the system in the course of work must be investigated. The proposed control system coupling two parallel three-phase PWM rectifiers and the application of direct current controller (DCC) to control systems in this paper will be analyzed with simulation and experimental results to produce a reasonable solution of this issue.