Design Technique and modification of Power line filter using passive lumped components

Abstract

A unique design technique of power line filter is being proposed. It is based on the conventional technique of composite low pass filter. The equivalent circuit of the composite low pass filter is being presented in the two different modes by considering the modal propagation of noise. The consideration of composite LPF is taken into account in the design technique of power line filter. In order to accurately predict the insertion loss of the filter the effects of non-ideal behaviour of the passive lumped components are considered. It is based on the parasitic effect of the passive lumped elements. The filter is then characterized using S-parameters. The response of the filter's circuits is simulated using advanced design software (ADS). Keywords: Conducted emission, Composite filter, electromagnetic compatibility, lumped elements, and power line filter. I. Introduction Switching and modulation techniques are used for efficient use of electrical power. Widely used Switched mode power supplies (SMPS) for powering today's electronics loads is a most common example. Unfortunately, all the power control techniques deliberately distort sinusoidal wave form of power frequency and generate unwanted interfering signals. Obviously, they all are often cited as one of the main source of conducted emission (CE). Usually the power supplies which are using controlling techniques cannot comply with the strict electromagnetic compatibility (EMC) regulations. In order to meet the limit set for conducted EMI, power supplies require a filter at its input. Conducted EMI generated through particular equipment gets coupled into other equipments mostly through power line cables. CE can be controlled by using filters and increasing line impedance. Conducted EMI has two components: The common mode (CM) interference and differential mode (DM) interference. The coupling mechanisms of these interferences are different (4). The difference in the direction of propagation of these coupling currents along the phase and neutral line, leads to differential mode ( ) current and common mode ( ) current. Therefore design of EMI filters demand decoupling of these two modes (2). This paper attempts to describe a design technique for Power Line filter using classical design technique. 1.1 Characterization of common mode & differential mode currents