This paper deals with efficient operation method for the electromechanical brake (EMB). A three-phase interior permanent magnet synchronous motor (IPMSM) is applied to the EMB operation. A current controller, speed controller, and position controller based on proportional-integral (PI) control are used to drive the IPMSM. Maximum torque per ampere (MTPA) control is applied to the current controller to perform efficient control. For MTPA control, the angle β is calculated from total input current, and the synchronous frame d–q axis current reference is determined by the angle β. The IPMSM is designed and analyzed with finite element analysis (FEA) software and current control is simulated by Matlab/Simulink using a motor model designed by FEA software. The simulation results were verified to compare with experimental results that are input current and clamping force of caliper. In addition, the experimental results showed that the energy consumption is reduced by MTPA.

Background: Active lateral suspension (ALS) technologies have been well developed for several decades, but they have not been widely used in service operation due to relatively high costs for implementation and maintenance and concerns about fail-safe. Therefore, this paper suggests a more practical approach for the active suspension system, designed to achieve target performance with easy implementation and maintenance and high fail-safe. Methods: The control performance target and actuator type are determined from the vibration energy that the ALS has to absorb along the weight function for ride quality evaluation. The installation position of actuator and sensor is decided to decrease the time that it takes for field engineers to check the actuator for maintenance. In addition to fail-safe function of ALS system, conventional hydraulic lateral damper is installed in parallel with ALS to reduce the concern about fail-safe of the ALS. Results: Through the roller rig and filed tests, the performance of the proposed ALS was validated. Lateral ride quality was improved 7.1dB and 6.7dB in the roller rig test and field test, respectively. The fail-safe strategy was also verified during the filed test. Conclusion: Test results show that the suggested ALS is designed appropriately and can be used in practical implementation.

In this paper, prior to the commercialization of a developed active steering bogie, we want to analyze steering performance experimentally according to steering angle level with the aim of obtaining steering performance data to derive practical design specifications for a steering system. In other words, the maximum steering performance can be obtained by controlling the steering angle at the 100% level of the target steering angle, but it is necessary to establish the practical control range in consideration of the steering system cost increase, size increase, and consumer steering performance requirements and commercialize. The steering control test using the active steering bogie was conducted in the section of the steep curve with a radius of curvature of R300, and steering performance such as bogie angle, wheel lateral force, and derailment coefficient were analyzed according to the steering angle level. As the steering angle level increased, the bogie indicated that it was aligned with the radial steering position, and steering performance such as wheel lateral force and derailment coefficient was improved. The steering control at 100% level of the target steering angle can achieve the highest performance of 83.6% reduction in wheel lateral force, but it can be reduced to about one-half of the conventional bogie at 25% level control and about one-third at 50% level. Considering cost rise by adopting the active steering system, this result can be used as a very important design indicator to compromise steering performance and cost rise issues in the design stage of the steering system from a viewpoint of commercialization. Therefore, it is expected that the results of the steering performance experiment according to the steering angle level in this paper will be used as very useful data for commercialization.

The steering performance according to the steering angle control was tested by using the active steering bogie developed to reduce excessive wheels and rail wear and noise generated when the railway vehicle run in a curved section. As a result of the test of increasing the steering angle in accordance with the target steering angle in the 300m radius of curvature, the bogie is gradually aligned in the radial steering position, and when the control is carried out to 100% of the target steering angle, the bogie angles of the front and rear bogies appeared almost the same. As the steering angle increased, wheel lateral force and derailment coefficient also decreased. Therefore, the validity of the radial steering position control method applied in this paper was confirmed experimentally. This test results will be used for future research on active steering bogie commercialization.

Active railway vehicles such as tilting trains and active steering bogies are being developed to improve the curve running performance of railway vehicles. In this case, a technology for sensing a curve and extracting curve information such as a curvature in real time is required. The existing railway curve detection technology has the disadvantage of requiring many calibration processes through test driving and being affected by running speed. In order to overcome these disadvantages, this paper proposes a very simple and efficient curvature estimation method. A curvature sensor prototype was manufactured and a test run was performed on the test track. As a test result compared with the track inspection data, the minimum deviation was 0.8%, the maximum deviation was 4.0% and the average deviation was 2.8%, showing good curvature measurement performance. It was also confirmed that the effect of the running speed was very small and the accuracy was high in the small curve with a large curvature. Therefore, the developed curvature measurement sensor is expected to be used very practically in the field of curvature detection and curvature extraction to control the vehicle in the curve section.