Research Of Two Phase Power Supply Of Electromagnetic Stirrer Controlled By Lpwm

EMS(Electromagnetic stirring) technology is in favor of ruling out the gas and inclusions in the melting metal, which is an effective method of improving the solidification structure of metals and product quality. Used EMS technology for continuous casting, it has been shown the good results about improving the quality of billet. In this thesis, the author studies the two modulation method SVPWM(Space Vector Pulse Width Modulation) and SPWM(Sinusoided Pulse Width Modulation)in depth. And he did a lot of experiments about the two modulation method on the experimental platform of the two phase electromagnetic stirring power supply which power is 160KW. Then the author proposed the LPWM(Logic Pulse Width Modulation) by analysising the voltage and current waveform on the experimental results. At last he used the LPWM modulation method in the electromagnetic stirring supply project, and the practice showed that the method is feasible. When the power supply with load, its current waveform is smooth and no obvious distortion. As the author applies with the main circuit form which is powered independently by capacitors about the stirring power supply . And he reduces the amount of its switch IGBT of inverter by half. So he saves the economic costs effectively.The Hardware controller chips of electromagnetic stirring power supply studied in this thesis is TI's TMS320F2812. The inverter output of this power supply is the two sine wave,and it is 90-degree difference between them.The current and frequency can be adjusted respectively. This power source control part is composed of integrated TMS320F2812 and S7200. And they control the power output and the human-computer interaction respectively. Due to the reason of time,it is faster that the author use the existing PLC program to control the human-computer interaction.It not only save engineering time,but also realize the requirements of the subject function effectively.The operation method of this power supply is easy to learn. Particulary it is suitable for operating at the harsh environment of Iron and Steel enterprises.First, the author analysis the functions of TMS320F2812 briefly, and the author reconstruct the main control panel which is used by the stirring power supply. Then he analysis the three modulation method which are SVPWM, SPWM and LPWM on theory, And the three modulation theory was programmed. And the author show the current and voltage's waveform when the power with no load, and the waveforms of the middle DC voltage, then he analysises them in detail. Finally, the paper was concluded, and made the prospects of the subject direction.