Study on suppressing harmonic flux density of converter transformer core under the DC bias

Under DC bias, the Converter transformer works from non-saturated area to saturated area. The harmonic current and harmonic magnetic flux of winding will increase. The converter transformer will badly vibrate. In this paper, we build a model of converter transformer by MATLAB which can be add DC voltage on line side or valve side. Under the two conditions, we can get harmonic current value of windings. A 2D FEM model of transformer can be build by ANSYS. According to the theory of coupled field-circuit, the converter transformer can be solved by transient. And Contrasting the electromagnetic properties of converter transformer in two conditions.