This paper studies WPT system for electrical trains. It discusses about the current drawbacks of using catenary&pantograph system for railway power supplying and mentions the merits of using WPT as a solution. About stationary WPT system, this paper mentions one of the biggest problems for its stable and efficient operation, that is coil misalignment. Then presents a coil position control system which can be used in railway applications, as a solution. For this coil position control system, as sensorless method to detect the position of coils is presented, which also shows a strong tolerance to vertical deviation of gap. As the result, the presented system is able move coils to the expected position with error less than 6.25% coil length, when gap deviation happens within (-50%~+100%).
Researches in 2015
- Wireless Power Transmission
- Permanent Magnet Synchronous Machine - Linear Drive
- Energy and Electric Drive Control of Railway Vehicle
- Motion Control Incorporating with Biological Architecture / Magnetic Levitation
Wireless Power Transmission
Permanent Magnet Synchronous Machine - Linear Drive
Most of point absorber wave energy converters in the ocean development stages are two-body and should be modeled as two-body system. In many researches, however, control strategies only for one-body converters were investigated. Furthermore, stability of closed loop was often neglected. In this paper, a stable impedance control to maximize electric output power of a two-body heaving point absorber is proposed. The numerical calculation results show superiority of proposed control strategy from the viewpoints of stability and electrical output power.
Armature resistance and electromotive force can be identified by conventional DC test and no load test. However, d-axis and q-axis inductances shall be measured by a new method. Authors propose to apply single-phase small AC-voltage to three phase winding to identify the two inductances by fixing mover to certain position. The proposed method will be explained in detail by numerical and experimental case studies.
Energy and Electric Drive Control of Railway Vehicle
In this study, a method of scheduling and running power control of train group are analysed in order to contribute sustainable transportation systems .In running curve design, power-limiting braking is considered because this braking method can maximise regenerative energy. This running curve design involving power-limiting braking can apply for conventional scheduling easily because this design method has a restriction of keeping running time. This means that this design method can maximise regenerative energy in restriction of conventional scheduling, and this method has been experimented on on-track test by using on-board computers and assistance interface devices in order to apply for an actual driving. In scheduling design, I propose the estimation of OD (Origin and Destination) of passengers and installing rapid service aims for reducing energy consumption and congestion. This scheduling design is one of the optimization problems so that Mixed Integer Programming method is considered. The background of this motivation has an relationship between rapid service for workers and local service for elders in declining birth rate and the graying of society.To combine these two design methods, I analyse an energy-saving effect of scheduling based on running curve with power-limiting braking. I prepare a case study model involving ATO (Automatic Train Operation) for on-track test because ATO system has an advantage of driving operation. In addition, I analyse an efficiency of enhancing hardware of rolling stocks, focusing on linear metro. The end effect and magnetic attractive force are considered because these has an effect on running resistance of rolling stocks. Now I am preparing and discussing in detail for on-track test. In addition, I am building out the calculation systems to analysis the electric-load leveling in electric railway.
Railway transportation is facing increasing pressure to reduce the energy demand of its vehicle due to increasing concern for environment issues. Therefore, strategies in effectively using energy are becoming even more important, and studies on operation method of train to reduce the total energy consumption are necessary, also. Since the total energy consumption can be modeled as a function depending on the running curve, it is possible to optimize the total energy consumption by searching an optimal running curve, given constraints of running time and motor force. However, the solution for this energy optimization problem is not easily obtained because the cost function demonstrating the relationship between the total energy consumption and the running curve is very complicated due to the nonlinear model of train, and because there are also nonlinear constraints given such as running time and motor force, etc. Therefore, in this research, we focus on studying (1) Modelization Methods to obtain the cost function and the constraint function based on a novel parameterization method of the running curve, and (2) Effective Optimization Techniques to solve the optimization problem. If both of above problems would be solved, Driver Guidance systems or Automatic Train Operation (ATO) systems are able to take advantage of pre-calculated running curve.
In this paper, energy consumption of entire train sets is analyzed to show the energy-saving effect when total traveling time of passengers is minimized by installing rapid trains. Results show that energy-saving effect by installing rapid trains depends on the number of boarding passengers and railway conditions, such as speed limits and gradients. In addition, it is confirmed that optimization of traveling time not only contribute the railway service but also save energy when traveling time is shortened by installing rapid trains.
Motion Control Incorporating with Biological Architecture / Magnetic Levitation
Redundant systems are of interest in engineering because they bring additional capability for a task completion, allowing the system to perform sub-tasks or to improve in performances. However, this also means that an extra degree of complexity is added to its resolution. For this purpose, proposed resolution schemes are classically based on the 2-norm minimization, also called pseudo-inverse, whose popularity stems from its easy analytical resolution, but suffer from not considering physical constraints, like input bounds. To tackle this issue, the infinity-norm resolution has been proposed, which determines a minimum-effort solution and take into consideration individual magnitudes and offering the full physically realisable outputs. Despite its guaranteed merits, it has only been considered for a few, low-order system because of its lack of analytical tractability. This paper proposes a novel approach on the minimum infinity-norm resolution for single-degree systems, which represent a large part of the most popular redundant configurations. This approach offers a closed-form solution allowing convenient computation and a description of the solution based on parameters of the system. Implementation of this new method is simulated on single-degree kinematically redundant systems to show the superiority of infinity-norm resolution over 2-norm resolution.
In this research, emphasize is put on developing a cost effective and affordable magnetic levitation module for translational motion applications. Since air gap sensors form a major portion in the total cost of the system, removing it can allow for drastic reduction in cost. Therefore, sensorless magnetic levitation for large air gap translational motion is investigated here. Most of the research in this field has been for magnetic bearings whose system characteristics and control requirements are different from a translational moving vehicle. An obvious difference is the range of operational air gap. Furthermore, the quality of magnetic materials, in terms of laminations, saturation, etc. used is also different. Therefore, applicability of the developed sensorless methods for magnetic bearings to large air gap applications needs to be investigated. A new method has been proposed that makes use of the high resolution-single current-ripple slope detection (either positive or negative) to compensate for the duty cycle variation by exactly controlling the timings of the gate signals for a switching amplifier without the use of a voltage sensor or a dedicated sense cycle as was done in recent preceding works. Furthermore, due to temperature change, the change in resistance which induces steady state error in air gap detection is compensated by simultaneously estimating coil resistance. Stable levitation using the detected air gap signal as control feedback has been demonstrated experimentally in our laboratory.