This paper compares the performance of unified power flow controllers (UPFCs), static var compensators (SVCs), and static compensators (STATCOMs) in commutation failure immunity (CFI) improvement of line-commutated converter-based high-voltage direct-current transmission (LCC-HVDC) systems. Theoretical analysis is presented to investigate the capacity requirements of SVCs, STATCOMs, and UPFCs to maintain the inverter-side ac voltage in the cases where three-phase faults occur on the receiving-end ac grids with different short-circuit ratio (SCR). Simulation studies were undertaken to validate the CFI improving performance achieved by UPFCs in comparison to SVCs and STATCOMs. Results of three-phase and single-phase fault tests manifest the superior CFI of LCC-HVDC systems having UPFCs installed. INDEX TERMS Commutation failure immunity, FACTS, LCC-HVDC, UPFC.

In order to eliminate mutual negative effect of brake, steering and suspension system, a kind of layered coordinated control method based on multiple controllers is put forward. Framework of coordination control system of chassis is established, coordination strategy of upper controller and control strategy of lower controllers are designed. The upper controller is used mainly to receive operation information of driver, running state of vehicle and feedback information of lower controllers, and send coordination control strategy to lower controllers. The lower controllers include controller of electro mechanical braking system (EMB), controller of electric power steering system (EPS) and controller of active suspension system (ASS), which are used to receive decision instruction of upper controller, control actuators to accomplish control tasks and send execution situation to upper controller in time.

Brake-by-wire is development direction of vehicle brake system, pedal feeling simulator is an important part of brake-by-wire. In this paper, one type of pedal feeling simulator whose damping is adjustable based on controllable rheological properties of magnetorheological liquid is proposed on the basis of analyzing relationship between pedal displacement and pedal pressure of traditional brake system. The structure is designed, damping is calculated, magnetic circuit is analysed and parameters are confirmed. The result shows that the pedal feeling simulator designed can meet actual requirements, and has certain practical value.

Based on the established full-car active suspension model, fuzzy control theory was combined with neural network control, the fuzzy neural network control system of vehicle active suspension was designed, simulation and analysis of random road input and sine wave input were carried on. The results show that, by comparison with the traditional suspension system, the peak and standard deviation of vehicle mass vertical acceleration decreased by 55.38% and 59.04%, the peak of vehicle mass vertical acceleration decreased by 49.96% when vehicle go through the sine wave at the speed of 5m/s, the ride comfort was improved obviously.

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