An Enhanced Magnetic Equivalent Circuit Model for a Magnetorheological Clutch Including Nonlinear Permeability, Flux Fringing, and Leakage Effects

Magnetorheological (MR) clutches have significant potential in electromechanical interface and are a promising technology with high commercial value in the automotive industry. A quick and precise magnetic circuit modeling method is demanded to calculate performance or optimize design of the MR clutch. Conventional magnetic circuit models present poor accuracy because they often fail to accurately include nonlinearities such as magnetic saturation, magnetic fringing, and magnetic leakage. In this regard, an enhanced magnetic equivalent circuit (EMEC) model based on lumped parameter method is proposed. This model can not only cope with clutch geometry and material properties (nonlinear permeability) but can also consider flux fringing and leakage effects. Combined with the specific structure, formulae for the calculation of fringing permeances and leakage permeances in the magnetic circuit of the MR clutch are presented. Finite-element analysis (FEA) and experimental results show that the proposed EMEC model can provide better accuracy compared with magnetic equivalent circuit (MEC) model from available literature and provide less computational effort compared with FEA. Moreover, the influence of design parameters corresponding to device geometry and material properties on the output flux density is discussed based on the proposed EMEC model. All taken together, the proposed EMEC model provides a comprehensive knowledge in optimize design and performance prediction of MR device.