Efficiency Evaluation of 800V Electric Vehicle Powertrain using Two-Level Voltage Source Inverter with different Modulation Techniques

Improving the inverter efficiency is important for electric vehicles (EVs) when tackling overall vehicle efficiency and increasing the driving range. This paper investigates the efficiency of an 800V EV propulsion system using an advanced modulation scheme called synchronous optimal pulse width modulation (SOP) and compares its performance to the conventional space vector modulation (SVM) scheme. A two-level voltage source inverter (VSI) using SiC power modules has been considered for benchmarking the effectiveness of the modulation schemes in terms of efficiency and performance. Earlier literatures has focused on efficiency comparison in a two-level voltage source inverter, but a detailed study of the modulation scheme called SOP is not well discussed. The impact of modulation schemes on the vehicle level has been analyzed using the Chevrolet Spark 2015 EV model in MATLAB/Simulink for different drive cycles. As a central evaluation criterion, this work examines the efficiency of a 1200V SiC traction inverter with a maximum output power of 350kW.

I. Introduction

High voltage systems are now becoming a trend in vehicle electrification because of the multiple benefits it offers in terms of improved performance and faster charging of the vehicle [1]. A higher voltage (for example, 800V or 1200V) propulsion system reduces the system current; hence the weight and volume of the AC and DC side busbars [2], [3]. This has been implemented in Porsche Taycan with various advantages, including a charging time of 22.5 minutes without increasing the size of the power cable [4]. A high-voltage propulsion system also reduces the conduction losses due to the reduced currents flowing through the semiconductor devices, which also improves the overall efficiency of the system [5].