Multilevel inverter power supply for electromagnetic stirring and control method for multilevel inverter power supply

Abstract

The invention discloses a multilevel inverter power supply for electromagnetic stirring and a control method for the multilevel inverter power supply. A high-voltage DC power supply is connected to aninput end of a clamping inverter power supply, and DC capacitor voltage is balanced by grading resistors. DC voltage outputs multilevel step waves through an inverter. A compound control system of current feedback control and feedforward control is adopted for an inverter side, on-off control is carried out on IGBTs of the inverter side, a left bridge arm and a right bridge arm output AC of whichthe phase difference is 90 degrees and electromagnetic thrust is formed through excitation, so that molten steel carries out rotational motion. A clamping multilevel H-bridge inverter module is adopted, so that compared with a traditional inverter power supply adopted for electromagnetic stirring, the multilevel inverter power supply has the advantages of being simple in structure, high in stability and low in production cost; and by adopting a multilevel technology, the equivalent switching frequency of a switching device is increased, the loss is reduced and the power quality of output current is improved.

Description

technical field [0001] The invention relates to a power supply for rotating magnetic field type electromagnetic stirring, in particular to a multi-level inverter power supply for electromagnetic stirring and a control method thereof. Background technique [0002] Electromagnetic stirring technology is beneficial to remove gas and inclusions in metal solution, and is an effective means to improve metal solidification structure and improve the quality of metal products. When the current-carrying molten steel is in the alternating magnetic field, a current will be induced in the molten steel, and the induced current will generate an electromagnetic force in the magnetic field to push the molten steel to move. [0003] In general, what the electromagnetic stirrer needs is a low-frequency, large-value sinusoidal alternating current. Changing the frequency and amplitude of the current can change the frequency and intensity of stirring. This stirring method has the energy concentra...

AI Technical Summary

Problems solved by technology

However, the current electromagnetic stirring power supply generally uses a conventional voltage source three-leg inverter main circuit, which has a large volume and the output voltage frequency is the same as the IGBT switching frequency. If you want to output high-frequency voltage, you must greatly increase The switching frequency of IGBT not only has switching loss, but also easily leads to the generation of switching noise and large torque vibration

At the same time, the structure of the three-arm inverter power supply is complex, the number of switching devices is large, and the production cost is high. The increase in the number of power thyristors also reduces the stability of the system and easily causes safety hazards.

At the same time, using the previous inverter power supply, in order to achieve a better steelmaking effect, the asymmetric winding motor is often used, which greatly reduces the usable range.

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