Common DC-Link Capacitor Harmonic Current Minimization for Cascaded Converters by Optimized Phase-Shift Modulation

• Published in: Energies (Basel) Vol. 16; no. 5; p. 2098
• Main Authors: Zhou, Xuanyi, Choy, Wei Juin, Alcaide, Abraham M., Wang, Shuo, Guenter, Sandro, Leon, Jose I., Monopoli, Vito Giuseppe, Franquelo, Leopoldo G., Liserre, Marco, Galea, Michael, Gerada, Chris, Buticchi, Giampaolo
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.03.2023
• Subjects: capacitor harmonic current; Capacitors; Critical components; DC-link capacitor; Design and construction; Direct current; Electric current converters; Electric vehicles; Fourier analysis; Harmonic analysis; harmonic minimization; interleaved boost converter; Inverters; Optimization; Phase shift; phase-shift modulation; Properties; Pulse duration modulation; Voltage converters (DC to DC); Spain
• ISSN: 1996-1073; 1996-1073
• DOI: 10.3390/en16052098

This paper investigates the influence of a constant carrier phase shift on the DC-link capacitor harmonic current of cascaded converters used in fuel-cell and mild-hybrid electric vehicles. In these applications, a DC-DC converter can be adopted between the battery and the motor drive inverter in a cascaded structure, where the two converters share the same DC-link. Since the DC-link capacitor of such a system represents a critical component, the optimization of the converter operation to limit the current stress and extend the lifetime of the capacitor is an primary objective. This paper proposes the use of a carrier phase shift between the modulations of the two converters in order to minimize the harmonic current of the DC-link capacitor. By harmonic analysis, an optimal carrier phase shift can be derived depending on the converter configuration. Analytical results are presented and validated by hardware-in-the-loop experiments. The findings show that the pulse width modulation carrier phase shift between the interleaved boost converter and the voltage source motor drive inverter has a significant influence on the DC-link capacitor current and thus on its lifetime. A case study with two-cell and three-cell interleaved boost converters shows a possible DC-link capacitor lifetime extension of up to 390%.