Development of a nonlinear thermal equivalent circuit model for the digital valve with integrated multiple coils

For the development of a digital valve, modularization, miniaturization, and low-temperature rise are crucial factors that need to be balanced against each other. A digital valve with integrated multiple coils based on a rectangular section magnetic sleeve is proposed to improve performance. To predicate the thermal performance of the proposed digital valve accurately and rapidly, a nonlinear thermal equivalent circuit (NTEC) model was developed. The most significant distinction of this model is its consideration of the changes in convective thermal resistance based on the operating temperature and installation state. This model has been derived and evaluated by simulation and experiments. The experiment results show that the temperature responses of four key test types obtained from the NTEC model have fairly good correspondence with to those from the experiment and the maximum temperature rise deviation is below 17 %. Finally, a comparison study with a C-type sleeve is demonstrated, indicating that the maximum temperature decline of the coil is 26.1 °C under a vertical state.