IGBT Medium-Frequency Power Supply

The IGBT is a composite device that combines the power transistor (GTR) and the power MOSFET. It integrates the advantages of both GTR and SFT, thus exhibiting excellent characteristics.

Technical Features

1. The IGBT is a composite device that integrates the power transistor (GTR) and the power MOSFET. It combines the advantages of both GTR and SFT, thus exhibiting excellent characteristics.
2. The IGBT medium-frequency power supply employs a circuit configuration in which capacitors are connected in series with the induction coil. Since frequency modulation and power regulation are used, the rectifier bridge operates in an uncontrolled state, resulting in a power factor of 0.96 or higher. Moreover, the operation generates minimal harmonics.
3. Compared to thyristors, IGBT transistors not only allow precise control over turn-on but also enable arbitrary and independent control over turn-off. Unlike thyristors, which rely on passive turn-off and require a certain amount of time to complete the process, IGBTs offer faster and more flexible switching, resulting in a higher inverter power factor (297%). With the same incoming line voltage (380V), the furnace voltage is significantly higher. The IGBT inverter operates at around 2800V, whereas conventional thyristor inverters typically reach only 750 to 800V at most—nearly four times higher. This higher voltage reduces line losses and allows for energy savings of up to 15%.
4. Constant power output. Compared to the traditional thyristor-based medium-frequency power supply, which adjusts voltage and power by regulating the input voltage, the IGBT-based medium-frequency power supply features frequency and power modulation that is largely unaffected by variations in charge quantity or furnace lining thickness. Throughout the entire melting process, it maintains a nearly constant power output. In contrast, during the heating process with a traditional thyristor-based medium-frequency power supply, the magnetic flux changes significantly, initially resulting in lower melting power and slower melting rates. The power output of the thyristor-based power supply varies with both melting time and magnetic flux—gradually increasing from low power to high power. This results in reduced utilization of transformer capacity and higher production costs. In this regard, energy savings can reach approximately 3% to 5%.