Quality and reliability optimization design for electromagnetic devices based on various uncertainties and time-dependent sensitivity analysis

Quality and reliability problems in electromagnetic devices (EMDs) have attracted wide attentions from companies in the competitive market. Various uncertainties from manufacture processing, operation environment and degradation path during the lifecycle of EMDs have great impacts on its performance and reliability. Robust design (RD) is one of most effective methods to improve both quality and reliability of EMDs. However, state-of-art RD methods ignore the correlations between various uncertainties and sensitivity analysis method is no longer applicable when the parameters are extended from central values to uncertainties. To better qualify uncertainties in manufacturing and understand the time-dependent derogation path, this paper proposed a method of quality and reliability optimization for EMDs, considering correlated uncertainties in design parameters and degradation path. Rosenblatt transformation is carried out to normalize different-type uncertainties and the results are quantitatively described by the hyper-rectangular method. Afterwards, a lifecycle sensitivity analysis method is proposed to determine the critical design parameter when parameter degradation exists during the operation of EMDs. Then, the optimization model was established considering parameter uncertainties and reliability constraint, and particle swarm algorithm is used to obtain the solution. Finally, the effectiveness of proposed method was verified by a case study of electromagnetic relay in electric vehicles.