Abstract
Attributing to the unique feature of zero carbon emission, electric vehicles (EVs) are attracting increasing interest in recent years, but their reliability, particularly the reliability of their critical components, is still a matter of concern today. In order to address this issue, much effort has been made before to assess the reliability of drive motor in the EVs. However, drive motor and motor controller are logically integrated and requested to work as one system in the EVs. In contrast to the individual reliability analysis of them, the combined assessment of the two parts can provide a more reliable prediction to the reliability of the entire motor system. Moreover, both drive motor and motor controller are composed of multiple components. The structure, type, and characteristics of these components may affect the reliability of the motor system as well. But these issues have not been considered in the previous research. In order to fill this gap of knowledge, the reliability of the entire motor system of pure electric vans that includes both drive motor and motor controller is investigated in this paper. In the research, the theoretical failure rates of subassemblies and components in drive motor and motor controller are predicted first. Then based on the failure rate prediction results, the reliability of the entire motor system (comprising both drive motor and motor controller) is assessed. Based on the assessment results, some interesting conclusions with respect to the most vulnerable subassemblies and components in the entire motor system and the potential disadvantage of existing reliability research are finally obtained. It is deemed that these new findings will be of great significance to the future reliability design and maintenance of pure electric vans.
Highlights
Encouraged by financial subsidies and policy dividends, the market of electric vehicles is booming across the world today
In order to provide a more reliable prediction to the entire motor system in pure electric vans, a detailed study of the reliability issues in both drive motor and motor controller are investigated in this paper by the approach of fault tree analysis
When the motor system continuously runs for 30,000 hours, the unreliability of drive motor is 0.033, but the unreliability of motor controller has reached as high as 0.147, which is about 4.5 times of the unreliability of the former;
Summary
Encouraged by financial subsidies and policy dividends, the market of electric vehicles is booming across the world today. The potential failures of wind turbine were qualitatively and quantitatively evaluated by using the fault tree analysis method in [14], and it was found that the majority of floating turbine failures are due to marine conditions, saltspray, and high wind speed; the fault tree analysis method was further improved in [15] in order to adapt to performing the qualitative analysis of complex systems containing multicomponent systems; the dynamic fault tree analysis model was developed in [16] to determine the average maintenance period of a floating wind turbine; the dynamic fault tree models were developed in [6] and [17] for assessing the reliability of a fault-tolerant control system and a vehicle guidance system in unmanned aerial vehicles; and so on In view of these previously successful applications of fault tree analysis, it will be taken in this paper to investigate the reliability of the motor system of pure electric vans.
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