In the home appliance industry, high-grade automatic rice cookers, induction cookers, variable frequency air conditioners, temperature-regulating health pots and high-grade temperature-regulating electromagnetic pots are all inseparable from igbt, a semiconductor device.
The process of changing alternating current into direct current is called rectification. Rectification technology was basically mature as early as 1980s. The process of changing direct current into alternating current is called inversion.
As early as 1980s, inverter technology relied on thyristor, commonly known as thyristor. Its principle is to add a DC power supply to the anode and cathode of the SCR, and then add it to the control group of the SCR through another trigger circuit. By adjusting the conduction time on the control electrode of the silicon controlled rectifier, the on-off of the DC power supply is determined, so as to realize the inverter of converting the DC power supply into the AC power supply.
Another scheme is to apply direct current to the transistor, which is usually called a switch tube. DC voltage is applied to the collector and emitter of the switch tube, and the switch tube is controlled to turn on and off by adjusting the potential of the base, thus realizing the inverter process of changing DC into alternating current.
No matter the thyristor technology or the on-off of the switch tube, these devices have the characteristics of large self-resistance, that is, large saturation voltage drop, because saturation voltage drop means that a large voltage drop will be generated when the circuit is turned on, which will bring a lot of heat.
At the same time, because the input resistance of the switching transistor is small, it needs a lot of excitation and driving current, so both thyristor and switching transistor have high requirements for the previous circuit.
Because of the characteristics of semiconductor materials, that is, the defects of small input resistance and large saturation voltage drop, its application range in high power output is limited. So for a long time, the current inverter technology has not made a big breakthrough.
At the end of 1980s, a new semiconductor device was born, which solved these problems in one fell swoop. This semiconductor device has the characteristics of high input impedance and low output impedance, and overcomes the defects of previous semiconductors. This semiconductor device is igbt.