Research On The Fault-tolerant Control Algorithm Of SVPWM For NPC Three-level Inverters

In recent years, multi-level inverter has been widely used in practical application because of its high power factor, low harmonics, high power and a series of advantages in large-capacity high-pressure situations. However, the multi-level inverter has some shortcomings, such as more switching devices, complex circuits and so on. This increases the use of the system cost, complexity of the system control, the more serious of which is to increase the probability of system failure, greatly reducing the reliability. Based on the most common problem of short circuit, the fault-tolerant techniques for NPC three-level inverters are studied in this article.In this paper, based on the most common topology of three-level NPC inverter, the space vector (SVPWM) control algorithm is analyzed, and targeted to the most common fault of short circuit, fault-tolerant theoretical and experimental studies are the focus of three-level inverter technology.Firstly, this paper describes the type of three-level NPC inverter topology, the basic working principle of voltage space vector (SVPWM) algorithm and fault-tolerant technology. Then, based on the above principle, the software control algorithm of SVPWM is studied, and the fault-tolerant control algorithm is obtained, using redundant vector instead of failure vector by analyzing the space after the short circuit.After a theoretical study, based on fault-tolerant control strategy, simulation model of the system is set up to achieve the SVPWM algorithm using MATLAB / SIMULINK. The results show the feasibility of the algorithm.Using laboratory resources, a comprehensive hardware circuit for three-level NPC inverter is built, including the main circuit and isolation drive circuit. The software is controlled by the type of DSP chip TMS320LF2407A, including SVPWM modulation and fault-tolerant strategies programming. Continuously through hardware and software debugging, waveform analysis and data from experiments prove the correctness of the design of the SVPWM control strategy issues, and the feasibility of using fault-tolerant algorithm to solve the system short-circuit failure.