Research On The Technology Of Low Frequency Inverter

Doubly-fed generator not only has variable speed constant frequency, and can largely adjust reaction power. It may improve the efficiency of power generation and the working stability of power grid in the water power and the wind power generation system.Doubly-fed motor can nimbly adjust the reaction power and the rotation rate that speed regulation range can reach 30%～50% under various load. It notably rise turns systematic efficiency and has very good energy-saving effect.The excitation control of low frequency inverter is key technology of doubly-fed. The research on the technology of low frequency inverter has important science significance and the vast application prospect. The traditional technology of low frequency inverter is cycloconverter. Since the cycloconverter need lots of component, the output voltage is rich in harmonic which is difficult to restrain and low-frequency range property is difficult to dispatch. So the AC-DC-AC pulse width modulation is used in low frequency inverter. The main circuit is to adopt the AC-DC-AC inverter, and TMS320LF2407A is key component of the control circuit in this paper.Firstly, the average switch period and dp0 revolution coordinate system model, which is about three-phase voltage inverter, is built. The every phase is no the coupling relation in the three-phase inverter, so the single-phase inverter is used in the control model. In order to research on low-frequency inverter, the control model of the single-phase inverter and the technology of Sinusoidal Pulse Width Modulation (SPWM) are built.Secondly, SPWM technology with the subsection synchronization modulation which aims to the property of bad resolution and plentiful harmonic in low frequency is researched. The harmonic is analyzed, so that the SPWM key parameters are optimized. To take appraises characteristic as the basis, the PWM technology is optimized by line voltage. Those indicate in theory that the technology of optimization PWM has the technical superiority for being used in the control system of low-frequency inverter. Finally, SPWM technology and PWM technology which is controlled by line voltage has separately been carried out simulation analysis in the technology of low frequency inverter.The simulation result indicated the optimized PWM technology comparatively is suitable for research on the technology of low frequency inverter. According to fundamental research and simulation analysis, the experimental system of low frequency inverter based on TMS320LF2407A as the central control unit has been built, and study of the control arithmetic which is about DSP is carded out. The part experiment of inverter in low frequency has been carried out, and that has got good controlling effect.