Technology Of SVPWM Space Vector Generation For Multi-level Converters

Multi-level diode clamp converter has obtained good application in some high power situations which energy can flow forward and back. Space vector pulse-width modulation (SVPWM) control method has become one of its most important control methods, for its low harmonic content,high voltage using efficiency convenience with digital realization and so on.Space vectors generation is the key part of SVPWM control of multi-level converters.One of the space vectors generation called table-inquire.It is easy to be accept,but its algorithm is complex and difficult to realize.In order to simple the space vectors generation,many new methods are suggested.There are two main methods in this article.One method is the disassembly of reference voltage vector.The reference voltage vector can be disassemble into two vectors: base vector and two-levels vector,then we can use the method which is similar to two-level space vector to choose three basic vector and calculate the time.The other method is based on the coordinate transformation,with m-n coordinate system and the K-L coordinate system separately replaces traditional coordinates system.This method doesn't need to involve tedious triangle operation and large numbers of computation during the judgement of vector sector and the time of computation vector.This article separately simulate the table-inquire method and the disassembly of reference voltage method with MATLAB software, then educe the concept of "vector generator".The vector generator is specially used for SVPWM space vector generation of the multi-levels converter,by a series of software and hardware.It's a module which firstly obtains the vector's magnitude and angle from the DSP processor,and secondly finish the driving signal's generation.This article in detail introduce several kind of vectors generators' feasible plans:"Based on DSP vector generator", "based on DSP+FPGA vector generator","based on FPGA vector generator". It is found that "based on DSP+FPGA vector generator" is easy to realize compared with two other plans.This article finally has built an experiment system based on the multi-levels vector generation.An experiment prototype of 1.5KW three-level inverter has been manufactured,which is driven by "based on FPGA vector generator".we finally got ideal wave in this experiment system.