电流源型逆变器的直接数字式空间矢量调制技术OA

To address the problems in the space vector pulse width modulation(SVPWM)of current source inverter(CSI)that switching signals cannot be directly generated through the comparison between digital modulation signals and carrier signals,and that the required additional hardware logic conversion circuits cause reliability degradation and signal delay,a direct digital implementation method of SVPWM for CSI was proposed.Firstly,the spatial distribution of basic vectors formed by all switching states was analyzed,and a sector determination method for the reference current vector was provided.Taking the first three sectors as an example,the calculation method for the duty cycle of adjacent vectors was derived;the expressions for vector selection and duty cycle calculation in all sectors were summarized,and the duty cycle in the over-modulation region was corrected.Then,the vector action sequence within a carrier cycle was mapped into switching action signals,and the configuration methods of action qualifier registers and compare value registers of the digital signal processor(DSP)under different sectors were summarized.Finally,the loop structure of the control system was designed,the proposed method was verified on a 3 kW experimental platform,and its steady-state performance was compared with that of the scheme adopting hardware logic conversion circuits.The experimental results indicate that the proposed method enables the DSP to output correct switching signal waveforms;the total harmonic distortion(THD)of current is only 0.99%,and the 5th and 7th harmonic contents are 0.100%and 0.105%,respectively.The current THD of the scheme adopting hardware logic conversion circuits is 1.46%,and the 5th and 7th harmonic contents are 0.180%and 0.160%,respectively.The proposed direct digital implementation method of SVPWM is correct and feasible,and it has superior steady-state performance due to the avoidance of signal transmission delay.