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In this paper, the mechanical model of two-degree-of-freedom vehicle semi-active suspension system based on time-delayed feedback control with vertical acceleration of the vehicle body was studied. With frequency-domain analysis method, the optimization of time-delayed feedback control parameters of vehicle suspension system in effective frequency band was studied, and a set of optimization method of time-delayed feedback control parameters based on “equivalent harmonic excitation” was proposed. The time-domain simulation results of vehicle suspension system show that compared with the passive control, the time-delayed feedback control based on the vertical acceleration of the vehicle body under the optimal time-delayed feedback control effectively broadens the vibration absorption bandwidth of the vehicle suspension system. The ride comfort and stability of the vehicle under random road excitation are significantly improved, which provides a theoretical basis for the selection of time-delayed feedback control strategy and the optimal design of time-delayed feedback control parameters of vehicle suspension system.

This paper proposes parameter controlling optimization of the time-delay feedback that is based on "equivalent harmonic excitation" in effective frequency band towards optimization of delay feedback control parameters for vehicle semi active suspension system. In this way, the optimal values of delay feedback control parameters based on different types of delay feedback control (displacement, velocity and acceleration) of wheels in the effective frequency band are obtained. Finally, through the stability analysis of vehicle semi-active suspension system based on different types of wheel delay feedback control and the numerical simulation analysis of time-domain response of suspension system performance evaluation index, the superiority of the time-delay feedback control strategy based on wheel displacement and the effectiveness and feasibility of the equivalent harmonic excitation optimization strategy are verified. Therefore, it provides a theoretical reference for the selection of time-delay feedback control strategy and the optimal design of time-delay feedback control parameters of vehicle active and semi-active suspension system.

It is hard to obtain the performance of the whole traction converter water-cooling system with different shape and route connecting tubes. In order to get the performance effectively and rapidly, the numerical simulation method is adopted to do that. The flow rate to every water-cooling heat sink is acquired through simulation analysis. Based on the flow rate, the temperature distribution of water-cooling heat sink has been investigated, and also the temperature variation of water-cooling system. The results show that the temperature difference between water-cooling heat sink is less than 1°C under the same inlet flow rate.With the purpose of verifying the accuracy and correctness of the numerical simulation method, the performance test also has been done.The difference of performance result between numerical simulation and test is below 6%, which demonstrates the accuracy and feasibility of numerical simulation method. Comparing with test, the numerical simulation method can greatly improve the design efficiency and save human and financial resources.