Analytical and Experimental Evaluation of SiC-Inverter Nonlinearities for Traction Drives Used in Electric Vehicles

Abstract

This paper investigates the inverter nonlinearities in a drive system based on SiC-MOSFETs and compares its performance with that of an equivalent Si-IGBT system. Initially, a novel comprehensive analytical model of the inverter voltage distortion is developed. Not only voltage drops, dead time and output capacitance, but also switching delay times and voltage overshoot of the power devices are taken into account in the model. Such a model yields a more accurate prediction of the inverter's output voltage distortion, and is validated by experimentation. Due to inherent shortcomings of the commonly used double pulse test (DPT), the switching characteristics of both SiC-MOSFETs and Si-IGBTs in the PWM inverter are tested instead, such that the actual performances of the SiC and Si devices in the motor drive system are examined. Then, the switching performance is incorporated into the physical model to quantify the distorted voltages of both the SiC-based and Si-based systems. The results show that, despite its existing nonlinearities, the SiC-based drive has lower voltage distortion compared to the conventional Si-based drive as a result of its shorter switching times and smaller voltage drop, as well as a higher efficiency. Finally, theoverriding operational advantages of the SiC-based drive over its Si-based counterpart is fully demonstrated by comprehensive performance comparisons.

Multi-Objective Optimal Design of Electro-Hydrostatic Actuator Driving Motors for Low Temperature Rise and High Power Weight Ratio

“…where h eq is the equivalent thermal conductivity, δ i is the thickness of the material and h i is the thermal conductivity of the material. The convective heat transfer coefficient in the fins of the housing, air gap and endcap can be calculated by Equations (4)- (8).Then the heat conductivity used in the 3-D steady state thermal analysis is listed in Table 14. Then, based on the above parameters, the steady state thermal analysis of the initial motor and the optimal motor were carried out when the motor was running at 6000 rpm and the output torque was 10 N•m.…”

“…Usually the winding of the motor is the hot spot due to the poor equivalent thermal conductivity. By inserting a high thermal conductivity conductor, a higher thermal conductivity path between the center of the slot and the housing can be established and the equivalent thermal conductivity improved [7,8]. However, this method will reduce the effective slot fill factor and the high conductivity conductor inserted in the slot will generate an eddy current loss.…”

Operation Efficiency Optimization for Permanent Magnet Synchronous Motor Based on Improved Particle Swarm Optimization

“…Under such circumstances, compared with internal combustion engine vehicles, electric vehicles (EVs) due to its zero emissions, high efficiency, and stable operating systems have received more attention from various countries [2]. The motor as the main power output sources of EVs is the link between the energy storage system [3][4][5] and the wheels, can effectively increase the endurance mileage of EVs in a single charge as choosing the appropriate motor and improving the operating efficiency of the motor [6]. The permanent magnet synchronous motor (PMSM) due to its high efficiency, simple structure, reliable operation, and small size [7] is always selected as the power output machine for EVs [8].…”

The Potential of SiC Cascode JFETs in Electric Vehicle Traction Inverters

“…The switching frequency of the SiC based inverter was twice that of the IGBT based inverter. In [15], SiC MOSFET based inverters were demonstrated to have better efficiency and lower output voltage distortion compared silicon IGBT inverters due to higher switching speed and smaller output capacitance.…”