Three-phase common mode (CM) inductors are widely used in motor drives to limit ground currents, axial voltages, and EMI emissions. With the help of high-performance switching devices such as SiC MOSFETs, the switching frequency of power converters is...
Three-phase common mode (CM) inductors are widely used in motor drives to limit ground currents, axial voltages, and EMI emissions. With the help of high-performance switching devices such as SiC MOSFETs, the switching frequency of power converters is increasing, and the role of common mode inductors is becoming more and more critical. This paper considers four levels for modelling three-phase inductors: common mode inductance, core losses, winding losses, and parasitic capacitance. Moreover, the leakage inductance of the three common mode inductors is described in detail from the solution path to the solution method. Regarding the saturation problem of inductors, a simple estimation can be made by the leakage inductance, which can avoid the saturation problem of the iron core. Because the parasitic capacitance greatly influences the inductance, the winding of the inductor is a double winding, and the centre tap is used, which can increase the coupling coefficient and reduce the leakage inductance. Three-phase common-mode parasitic capacitance has a turn-to-turn capacitance, turn-core capacitance and winding capacitance, which can be equated to turn-turn capacitance and turn-core capacitance into C_a, turn-core capacitance and winding capacitance can be equated to C_N when the common-mode signal through the common-mode inductors there will not be a signal flowing through the parasitic capacitance of the two windings, so the Cn can be not to be taken into account. The parasitic capacitance is only C_a. In order to eliminate the parasitic capacitance, the centre tap of the inductor is connected to an external capacitor that is about four times larger than the parasitic capacitance and the resonant frequency of the impedance is made more significant by comparing the insertion voltage gain using the PSM1735; by using the double-winding common-mode inductors to build the EMI filter, the results prove that, although a relatively large capacitance is introduced, the parasitic capacitance of the inductors themselves is It is proved that the parasitic capacitance of the inductor itself is significantly eliminated. Moreover, the filter constructed by the dual-winding common-mode inductor is placed in the three-phase inverter circuit, and the filtering effect is better than that of the traditional three-phase common-mode inductor. Thus, the proposed dual-winding three-phase common-mode inductor can reduce the effect of capacitance on the inductor through the particular winding method.