Hybrid Output Voltage Modulation (PWM-FSHE) for a Modular Battery System Based on a Cascaded H-Bridge Inverter for Electric Vehicles Reducing Drivetrain Losses and Current Ripple

Abstract

This paper shows a preliminary study about the output voltage modulation of a modular battery system based on a seven-level cascaded H-bridge inverter used for vehicle propulsion. Two generally known modulation techniques, pulse width modulation (PWM) and fundamental selective harmonic elimination (FSHE), are extensively compared for such an innovative modular battery system inverter considering EVs’ broad torque-speed range. The inverter and the battery losses, as well as the inverter-induced current THD, are modeled and quantified using simulations. At low speeds, if the modulation index M is below 0.3, FSHE induces a high current THD (>>5%) and, thus, cannot be used. At medium speeds, FSHE reduces the drivetrain losses (including the battery losses), while operating at higher speeds, it even reduces the current THD. Thus, an individual boundary between multilevel PWM and FSHE can be determined using weightings for efficiency and current quality. Based on this, a simple hybrid modulation technique is suggested for modular battery system inverters, improving the simulated drive cycle efficiency by a maximum of 0.29% to 0.42% for a modeled small passenger vehicle. Furthermore, FSHE’s high speed dominance is demonstrated using a simple experimental setup with an inductive load.

Detailed Power Loss Analysis of T-Type Neutral Point Clamped Converter for Reactive Power Compensation

“…Thanks to these converters, it was possible to efficiently convert electrical energy without using expensive and large transformers [3,4]. Over the years, it has become clear that many multilevel converter topologies often have better performance parameters than the classic two-level converter, even at low voltage levels [5][6][7][8][9]. One of the most important features of these converters is high efficiency, which was not always an obvious fact with the greater number of semiconductor devices used in converters with a very high number of voltage levels [10][11][12].…”

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Review of Technical Design and Safety Requirements for Vehicle Chargers and Their Infrastructure According to National Swedish and Harmonized European Standards

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“…The charging modes of PHEV and BEVs are classified into four types based on the charging station type [17]. A detailed view of the types of charging modes is given in Table 2 [18][19][20][21].…”

“…The charging modes of PHEV and BEVs are classified into four types based on the charging station type [17]. A detailed view of the types of charging modes is given in Table 2 [18][19][20][21]. The charging modes of PHEV and BEVs are classified into four types based on the charging station type [17].…”