Frequency conversion method of non-ferrous metal electromagnetic stirrer and frequency conversion device for realizing frequency conversion method

Abstract

The invention discloses a frequency conversion method of a non-ferrous metal electromagnetic stirrer and a frequency conversion device for realizing the frequency conversion method. The method comprises the following steps of: storing self parameters and control parameters of the stirrer in a memory; calculating and converting the parameters into a plurality of static pulse trigger angle information for controlling the motion of an inverter set and duplicating the information into a mapped memory as dynamic pulse trigger angle information; detecting a voltage value of the input end of the inverter set; detecting an output current value; comparing a practical periodic value of load current with a preset value; according to the difference between the practical periodic value of the load current and the preset value, quantitatively adjusting a ratio of an expected output voltage effective value to a practical input voltage effective value in a conduction angle calculation formula to correct the plurality of dynamic pulse trigger angle information one by one; then, sequentially outputting the plurality of dynamic pulse trigger angle information to drive the inverter set to work; and finally, enabling a practical frequency conversion frequency to be same as a preset frequency. The frequency conversion method of the non-ferrous metal electromagnetic stirrer, disclosed by the invention, has the advantages of good output waveform consistency and working stability and reliability.

Description

technical field [0001] The patent of the present invention relates to a frequency conversion method of a non-ferrous metal electromagnetic stirrer and a frequency conversion device for realizing the frequency conversion method. technical background [0002] In order to improve the quality of non-ferrous metal products, the liquid metal must be fully stirred during the metal smelting or melting process. Stirring methods mainly include manual stirring and electromagnetic stirring. Among them, manual stirring has poor stirring quality and low stirring efficiency, but has the advantage of low cost. The working principle of electromagnetic stirring is: the variable frequency power supply sends ultra-low frequency alternating current to the induction coil of the electromagnetic inductor, and the iron core of the inductor generates a traveling wave magnetic field. When the traveling wave magnetic field penetrates the stainless steel at the bottom of the furnace and the furnace lin...

AI Technical Summary

Problems solved by technology

This frequency conversion method is fast in action, convenient in control, and simple in implementation. The disadvantages are: 1. Poor anti-interference; when the input voltage fluctuates, the frequency conversion output current waveform will change accordingly, resulting in inconsistent output current parameters with the set parameters. , is inconsistent with the control parameters such as the set frequency, and the error is large; 2. Poor adaptability; when the parameters of the electromagnetic stirrer itself change due to changes in the natural environment or maintenance, the frequency conversion output waveform will also change accordingly, which is different from the set frequency, etc. The control parameters are inconsistent; 3. The control precision is low, which makes the frequency conversion output waveform poor in consistency. In the case of electromagnetic stirring with complex working conditions, the output waveform will appear asymmetrical or even distorted. Seriously, the electromagnetic stirrer will not work normally.

The frequency conversion device of the traditional non-ferrous metal electromagnetic stirrer has a simple structure and low cost. The disadvantage is that the control accuracy is low and the reliability is poor, which will easily cause the non-ferrous metal electromagnetic stirrer to crash and seriously affect the normal operation of the electromagnetic stirrer.

Images