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Magnetohydrodynamic Calculation on Double-Loop Channel Induction Tundish

Yue Q., Pei X., Zhang C., Wang X.

Archives of Metallurgy and Materials

2018

Vol. 63, iss. 1

329--336

A mathematical model is developed to investigate the electromagnetic induction heating in a continuous casting tundish with the double-loop inductor. Maxwell’s equations are solved using finite element method to obtain the magnetic flux density, electromagnetic force, and Joule heating. Results show that the induced current through the two channels generates a current loop. The electromagnetic force points to the center of the channel, thus generating a pinch effect on the molten steel. With the skin effect and proximity effect, Joule heating rate reaches its maximum and minimum values at the corners and the center of the crosssection area respectively. Power ampere-turn has a significant influence on the electromagnetic force and Joule heating density. As ampere-turns vary from 3.6×104 to 2.16×105, Joule heating rate increases from 2.4 MW m-3 to 85 MW m-3. Electromagnetic force also increases from 8×104 N m-3 to 3×106 N m-3 in the center axis line of the channel. The present work reveals the relationship between magnetic flux density and electromagnetic force. The results will be helpful in adjusting the electromagnetic field in channel-induction furnaces and modifying the design of channel parameters.

Voltage/current control mode for combined three-phase inverter

Wang H., Yue X., Pei X., Kang Y.

Przegląd Elektrotechniczny

2010

R. 86, nr 11a

358-362

For parallel inverters system, controlling the output voltage in normal operation constantly is named the voltage control mode (VCM), and controlling the output current constantly in abnormal operation conditions (such as short circuit) is named the current control mode (CCM). The combined three-phase inverter topology is presented, the equivalent inverter topology with a LCL filter is obtained and mathematical models are built in VCM and CCM. A hybrid control strategy is proposed. The PID control and the repetitive control are used in VCM to obtain the fast dynamic responses and low harmonic distortions. On the other hand, the state feedback control is used in CCM. Pole assignment has been employed in designing parameter of the PID controller and state feedback, and the repetitive control design process is given. Experimental results validate the proposed control using two 400KVA parallel inverters.

Dla równoległego systemu przekształtników zazwyczaj stosuje się system kontroli napięcia VCM i system kontroli prądu CCM (w warunkach specjalnych - np. zwarcia). Zaprezentowano topologie przekształtnika trójfazowego. Odpowiednia topologia przekształtnika z filtrem LCL została przedstawiona. Zaproponowano hybrydową strategię sterowania. System PID sterowania użyty w VCM zapewnia szybką odpowiedź dynamiczną i małe zniekształcenia. W układzie CCM użyto stałego sprzężenia zwrotnego. Sprawdzono położenie biegunów. Wyniki eksperymentu z dwoma 400kVA równoległymi przekształtnikami potwierdziły założenia.