Introduction and Comparison of SCR and IGBT Rectifiers

2025.07.21

Silicon Controlled Principle

The AC input voltage is regulated by the silicon controlled thyristor and then transformed to the transformer to obtain the LV AC power. Then, it is integrated into the DC through the silicon controlled thyristor to obtain the required output voltage and current.
The control circuit samples the output voltage and output current, and controls the phase angle at the moment when the thyristor triggers conduction through the phase control mode after closed-loop feedback, so as to keep the output voltage or current stable.

Main Components of SCR

In the early stage, the transformer was mainly cooled by oil, i.e. immersed in the oil tank. Due to the larger specific heat of oil than air and higher insulation strength, this heat dissipation mode is the mainstream heat dissipation of high-power transformer.
However, due to the maintenance of oil products, the sealing at the outgoing line is not easy to solve. With the progress of insulation materials, dry type transformers have taken the leading position in medium and small power levels.
Dry-type transformers are cooled by air. The transformer can also be water-cooled, that is, the coil of the transformer is made hollow, and the purified water is used to take away the heat.

IGBT rectifier Principle

The AC input voltage is filtered by the rectifying circuit to obtain a higher DC voltage. The "frequency conversion" inverts the HVDC into a high-frequency AC of about 15KHZ, which is converted to the secondary by the high-frequency transformer, and then the required output voltage is obtained by the high-frequency rectification filter. The control circuit samples the output voltage and output current, and generates a pulse width modulation (PWM) signal after the dead cycle feedback to control the "power conversion" circuit, so as to keep the output voltage or current stable.

Performance Comparison

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