Characteristics of SiC inverter powertrains on common-mode EMI noise

Abstract

This paper studies the characteristics of SiC inverter powertrains on common-mode (CM) EMI emission. First, a CM noise source model of an EV powertrain is built. Then, the factors of switching frequency, switching speed, and switching ringing on the CM noise source are analyzed. Finally, experiments on a conducted EMI test-bed are carried out to verify the influence of SiC inverters on conducted CM EMI emission in EV powertrains.

Appendix

Assuming that the electrical parameters of the three-phase ac system are symmetrical:

$$Z_{A} = Z_{B} = Z_{C} .$$

(11)

To solve the circuit shown in Fig. 3, node G is selected as the reference node. The following equations can be obtained for nodes A, B, and C, as well as node N(P):

$$\begin{aligned} \frac{{V_{\text{LISN}} + V_{AN} }}{{Z_{A} }} + sC_{\text{d}} \left( {V_{\text{LISN}} + V_{AN} } \right) + I_{AN} = 0 \hfill \\ \frac{{V_{\text{LISN}} + V_{BN} }}{{Z_{B} }} + sC_{\text{d}} \left( {V_{\text{LISN}} + V_{BN} } \right) + I_{BN} = 0 \hfill \\ \frac{{V_{\text{LISN}} + V_{CN} }}{{Z_{C} }} + sC_{\text{d}} \left( {V_{\text{LISN}} + V_{CN} } \right) + I_{CN} = 0 \hfill \\ I_{AN} + I_{BN} + I_{CN} = \frac{{V_{\text{LISN}} }}{{Z_{\text{LISNs}} //\frac{1}{{s3C_{\text{d}} }}}}. \hfill \\ \end{aligned}$$

(12)

where V_AN, V_BN, V_CN, I_AN, I_BN, I_CN, and V_LISN are the Laplace transform of v_AN, v_BN, v_CN, i_AN, i_BN, i_CN, and v_LISN, respectively.

According to (12), the voltage V_LISN can be derived as follows:

$$V_{\text{LISN}} = - \frac{{Z_{\text{LISNs}} //\frac{1}{{s3C_{\text{d}} }}}}{{Z_{\text{LISNs}} //\frac{1}{{s3C_{\text{d}} }} + \frac{{Z_{A} }}{3}//\frac{1}{{s3C_{\text{d}} }}}}\frac{{V_{AN} + V_{BN} + V_{CN} }}{3}.$$

(13)

Here, the CM noise source V_CM0 is defined as follows:

$$V_{\text{CM0}} = \frac{{V_{AN} + V_{BN} + V_{CN} }}{3}.$$

(14)