Quang-Anh Nguyen

Development of a multi-pole magnetorheological brake

This paper presents a new approach in the design and optimization of a novel multi-pole magnetorheological (MR) brake that employs magnetic flux more effectively on the surface of the rotor. MR brakes with conventional single ring-type electromagnetic poles have reached the limits of torque enhancement. One major reason is the limitation of the magnetic field strength within the active area of the MR fluid due to the geometric constraints of the coil. The multi-pole MR brake design features multiple electromagnetic poles surrounded by several coils. As a result, the active chaining areas for the MR fluid are greatly increased, and significant brake torque improvement is achieved. The coil structure, as a part of the stator, becomes flexible and customizable in terms of space usage for the winding and bobbin design. In addition, this brake offers extra options in its dimensions for torque enhancement because either the radial or the axial dimensions of the rotor can be increased.Magnetic circuit analysis was conducted to analyze the effects of the design parameters on the field torque. After that, simulations were done to find the optimal design under all major geometric constraints with a given power supply. The results show that the multi-pole MR brake provides a considerable braking torque increase while maintaining a compact and solid design. This is confirmation of its feasibility in actual braking applications.

A Study of Novel Hybrid Antilock Braking System Employing Magnetorheological Brake

A novel hybrid antilock braking system (ABS) with the combination of auxiliary brake and a multipole magnetorheological (MR) brake was proposed in this paper. The MR brake with innovative operation concept can replace existed hydraulic brake system or works as an auxiliary brake. Two simulation models of the MR brakes, inner rotor and outer rotor structures, have been built. The outer rotor design was chosen due to its better braking performance and suitable mechanism for using on motorcycle. After that, motorcycle simulation software was employed to validate the hybrid ABS system under appropriated working condition. Two controllers, the ordinary and self-organizing fuzzy logic controllers (FLC and SOFLC), were evaluated on ABS performance to pick the suitable one. Simulation results confirm the more adaptations to different road conditions of the SOFLC with 18% higher brake performance compared to ones of ordinary FLC. Brake performance can increase 12% more with the combination of SOFLC and road condition estimator (RCE). It is concluded that this hybrid ABS is feasible for actual application by effectively improving the brake performance for ensuring driving stability.

Design and validation of outer rotor magnetorheological brake with multiple poles

Abstract A magnetorheological brake with multiple poles and an outer rotor structure is introduced in this paper. It is designed to be used as a resistant source for bicycle training equipment. The outer rotor structures works as a roller against the bike rear wheel for indoor exercise. The key factors to affect the brake torque were found after an analysis of the magnetic circuit of the brake. Two structures with different pole numbers were simulated to find the optimal one which harmonises between the maximum output torque and the input power. Simulation results confirm the feasibility of the outer rotor magnetorheological brake concept. The optimal brake was later manufactured and experimented for validation. Its torque can be controlled precisely by an input current with a very fast response. The maximum brake torque is 5 Nm at a 0·9 A input current. Those phenomena are applicable for the bicycle training equipment. Moreover, the compact design of the brake shows advantages in weight and space reductions.