Electromagnetic heating system and working method thereof

Abstract

The invention discloses an electromagnetic heating system and a working method thereof, and the system is provided with a control module, a power switch tube drive circuit module, a power switch tube module, and an LC resonant module, wherein the LC resonant module is provided with a DC input capacitor and a capacitor switching module. When an IGBT needs to be turned on, a switching capacitor circuit module is started firstly and then a DC input capacitor is cut off from the LC resonant module, thereby reducing the voltage of the collector electrode of the IGBT. Afterwards, the IGBT is started again, the IGBT is enabled to work in a soft start state, and then a DC input capacitor is connected to the LC resonant module again, and the circuit recovers to a normal state. According to the LC oscillation working principle, the DC input capacitor is cut off at a proper moment, and the voltage of the collector electrode of the IGBT is reduced at the ON moment of the IGBT, and the IGBT is enabled to work in the soft start state, thereby reducing the amplitude value of a big impact current generated at a hard on-off state, reducing the electromagnetic EMI interference and noise, and guaranteeing that the IGBT works in a safe current range.

Description

technical field [0001] The invention relates to the field of induction heating, in particular to an electromagnetic heating system. Background technique [0002] The electromagnetic heating cooking system in the related art is usually turned on when the collector voltage of the power switch tube is close to zero volts. At this time, it is in a soft switching state, and the loss of the power switch tube is small. However, its disadvantage is that there is an input DC capacitor in the LC resonant module. Normally, the voltage across the capacitor is the rectified DC bus voltage, which is too high. The collector voltage of the power switch tube is approximately the voltage across the capacitor. When the LC resonance circuit does not have enough energy to reduce the collector voltage of the power switch tube to zero volts, the power switch tube will be turned on when its collector voltage is not zero, and it is in a hard switching state at this time; The impact current is very...

AI Technical Summary

Problems solved by technology

When the LC resonance circuit does not have enough energy to reduce the collector voltage of the power switch tube to zero volts, the power switch tube will be turned on when its collector voltage is not zero, and it is in a hard switching state at this time; The impact current is very large. On the one hand, it will generate electromagnetic EMI interference. On the other hand, it will cause the current of the resonant capacitor and power switch tube to exceed its safe operating range. Long-term work is easy to damage components and reduce the service life of the product.

Images