A Common Mode Noise Suppression Method for Flyback Circuit

doi:10.16628/j.cnki.2095-8188.2022.11.006

Abstract

Abstract:

In order to improve the EMI characteristics of flyback converter,based on the analysis of the parasitic capacitance model of Flyback transformer,the switching period decomposition of common mode noise on transformer is carried out,and the generation and transmission mechanism of common mode noise is obtained.Two method to balance common mode noise with windings are proposed.According to the proposed method,the optimal number of turns is calculated to balance the common mode noise,which can balance the common mode noise flowing through the parasitic capacitance of the transformer and improve the EMI characteristics of the circuit.Finally,a 40 W flyback LED driving power supply is used for experiments,and the EMI characteristic curve of the prototype is given,which can verify the effectiveness of the proposed method.

Key words: flyback circuit, common mode noise, EMI, noise balance, parasitic capacitance

CLC Number:

TM46

XIAO Jian, LIN Weiming, ZHANG Liangliang, XIAO Zhantao. A Common Mode Noise Suppression Method for Flyback Circuit[J]. LOW VOLTAGE APPARATUS, 2022, 0(11): 32-38.

Figures/Tables 12

References 14

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参数	变压器类别
参数	第一类	第二类	第三类
主感量/μH	1 100	1 100	1 100
一次侧绕组N_p/匝	47	47	47
二次侧绕组N_s/匝	24	24	24
一次侧平衡绕组N_Psh/匝	0	16	44
二次侧平衡绕组N_Ssh/匝	0	0	23
一次侧辅助绕组N_AP/匝	9	9	9
二次侧辅助绕组N_AS/匝	10	10	10

参数	数值
平衡绕组匝数/匝	10	13	16	18	20	23	25
EMI余量/dBμV	0	2.14	3.86	2.36	1.85	0	0