Quantitative Reliability Evaluation of Silicon Carbide-Based Inverters for Multiphase Electric Drives for Electric Vehicles
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Advanced Electric Machines and Power Electronics Lab, Texas A&M University, College Station, TX, USA
Power Electronics and Drives 2022;7 (42):29-42
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ABSTRACT
Reliability of power converter in the electric drivetrain of a vehicle can be a criterion for the comparison of various converter topologies,
cooling system designs and control strategies. Therefore, reliability prediction is important for the design and control of vehicles. This
paper presents an approach for quantitative evaluation of the reliability of converters for multiphase motor drives for electric vehicles
(EVs) after considering the driving cycle. This paper provides a good background of reliability quantification so that it is easy to extend
the presented approach to other applications. The models of subsystems have been selected to have excellent computational efficiency
with good accuracy which is necessary for simulating long driving cycles. A simple vehicle model is used to obtain the traction motor
torque demand for various points of the driving cycle. A multiphase interior permanent magnet synchronous motor has been used
for traction motor. The operating voltage and currents of the motor are found using maximum torque per ampere (MTPA) control of
IPMSM. The analytical loss calculation has been used to find the losses of switching devices of the converter. A thermal model of
silicon carbide (SiC) MOSFET has been used to calculate junction temperature from the losses. The model developed here gives the
failure rate and mean time between failures (MTBF) of switching devices of the inverter, which can be used to determine the failure
rate. The model has been used to find the transition probabilities of a Markov model which can be used to quantify the reliability of
converters of multiphase electric drives.