EMI Consideration of High Reliability DC-DC Converter: In Aerospace Based Electric Transport System Charger Application

High reliability and low electromagnetic interference (EMI) are two important factors for many industrial applications such as air based electric transport system charger (AETSC). Therefore, it is essential to introduce high reliability and low EMI power converters. This paper presents a new high reliability and low current ripple DC-DC converter. For the proposed converter, a spectrum analysis approach for suppressing the EMI using chaotic sinusoidal pulse width modulation is provided. In addition, the proposed converter has radio frequency (RF) EMI lower than 100 kHz. However, for higher than 100 kHz, EMI issue of the proposed converter has unsuitable situation. 1. NOMENCLATURE A: amplitude of signal, fc: carrier signal, υm(τ): unitary amplitude of modulated signal, kω: a controlled factor, TC : the main frequency of switch which is a constant, xn: the nth output of chaotic mapping, β: a modulation factor. 2. INTRODUCTION In AETSC applications, a power subsystem generates, distributes, regulates power, and stores it for periods of peak demand. The power subsystem may also need to convert and regulate voltage levels or supply multiple voltage levels. A power switch acts in onor off-state. Hence, it is essential to increase the reliability of the converter. Moreover, it is necessary to protect it against short circuits and isolated faults. A satellite electric transport system, in some technologies, is fed through common DC bus. A subsystem includes communication, control and other sections. The importance of proper functioning of the subsystem depends on the electric transport system mission. EMI is a popular problem in electric transport systems. High-speed switching in power subsystems is the main source of EMI. Switching in power conversion system generates conducted EMI noise through DC line between the power converter module and ground. In general, the flowing noise between two lines is called differential mode (DM) noise, and the flowing noise between each line and ground is called common mode (CM) noise. CM mode noise is mainly conducted through parasitic capacitance between component and ground plane. It is excited by the common mode voltage, which is source voltage of the top device or drain voltage of the bottom device in a phase. Also, the produced common mode voltage in motor terminals is the reason of leakage current. High value of dv/dt is also responsible for CM EMI as identified in [1–3]. On the other hand, High di/dt may result in differential mode (DM) EMI [4, 5]. Stray capacitors are excited by increasing the switching frequency. Stray capacitance consists of the capacitance between motor winding and motor body, power switch drain-source capacitor and other known and unknown capacitors. Received 25 November 2015, Accepted 20 January 2016, Scheduled 3 February 2016 * Corresponding author: Tohid Rahimi ([email protected]). The authors are with the Electrical and Computer Engineering Faculty, University of Tabriz, Iran.