The paper proposes a high precision simulator for the following mode system design in Hard Disk Drives (HDDs). The simulator is composed of two models: one is a precise mechanical plant which includes numerous high frequency vibration modes, and the other is a disturbance signal model which is separated into various disturbances. In the proposed approach, a differential iteration method is applied to identify the precise mechanical plant, providing accurate experimental model analyses. The effectiveness of the synthesized simulator was verified by the comparative studies for experiments and numerical simulations.
In Hard Disk Drives, there are two seek modes. One is a short distance seek mode, the other is a long distance seek mode. There is not saturaliton in the short distance seek mode, so many methods were proposed to realize a low acoustic noise and low vibration seek. However, in order to realize a low acoustic noise seek in Hard Disk Drives, the long distance seek mode is very important. So, a new method for the long distance seek is proposed in this paper. In conventional methods, a reference velocity curve is used. This reference velocity curve can be considered a switching line in the phase plane. In the proposed method for a long distance seek, the sliding mode controller with a frequency-shaped switching line is designed for a feedforward controller. The advantage of this method is a hign frequency ingredient in the feedforward input can be eliminated by setting the frequency-shaped switching line. The validity of the proposed method was confirmed by numerical and experimental results using a miniature 2.5-inch Hard Disk Drive.
An algorithm optimizing train running profile with Bellman's Dynamic Programming (DP) is investigated in this paper. Optimal running trajectory of a train which minimizes amount of total energy consumption has been produced under fixed origin and destination, stipulated running time and various track profile. Many previous works on this area adopt the numerical techniques of calculus of variations, Pontryagin's maximum principle, and so on. But these methods often meet some difficulties accounting for complicated actual train running preconditions, e.g. complicated functions which describe electrical motive/brake torque, local constraints of the state variable as speed limitations, non-linear running resistance and variable grade profiles. Basic numerical DP algorithm can cope with such comlicated conditions and give the globally optimal solution. But this method consumes too large computation time for practical uses. We have made the improvements for shorter calculation time of whole optimization process and reducing the numerical error. The confined state space and irregular lattice play most important role for them. Dynamic meshing and effective utilization of system memory also realize shorter computation time. The effectiveness of the proposed method is demonstrated using various complicated running conditions.
In this paper, the analysis and the modelling of a Dual-Stator Induction Motor (DSIM) are presented. In particular, the effects of the shift angle between its three-phase windings are studied. A complex steady state model is first established in order to analyse its harmonic behavior when it is supplied by a non-sinusoidal voltage source. Then, a new transformation matrix is proposed to develop a suitable dynamic model. In both cases, the study is made using an arbitrary shift angle. Simulation results of its PWM control are also presented and compared in order to confirm our theoretical observations.
Coiling temperature is one of the most significant factors in products of hot strip mill to determine material properties such as strength, toughness of steel, so it is very important to achieve accurate coiling temperature control (CTC). Usually there are a few pyrometers on the run out table in hot strip mill, therefore temperature model and its adapting system have large influences on the accuracy of CTC. Also unscheduled change of rolling speed has a bad effect to keep coiling temperature as its target. Newly developed CTC system is able to get very accurate coiling temperature against uncertain factors and disturbances by adopting easily identified temperature model, learning method and dynamic set up function. The features of the CTC system are discussed with actual data, and the effectiveness of the system is shown by actual control results.
This paper presents a new instantaneous current control to obtain an instantaneously flat torque waveform with smaller torque ripples of switched reluctance motors (SRMs). The proposed current control is based on table lookup. By geometric insights for the machine and finite element method based analysis, ideal current profiles for the flat torque are generated. Some simulation results are presented to demonstrate the validity of the proposed control, which are verified by experiment.
This paper presents the charging method of the capacitor energy for the new concept of voltage transient sag compensator. This compensator consists of the series connection inverter units, and each inverter unit generates a different output voltage by 2n times. Namely, in this system, the compensation energy is accumulated in each inverter unit's capacitor charged with different voltage by 2n times. The method proposed here, provides the fast charging method of the capacitor energy from these inverter units without using rectifier system.
One of the most important technologies for electric vehicles (EVs) will be drive control technology for main motor. It is desired for the drive control technology to have the following characteristics. 1) It does not require a position/speed sensor for controlling motor drive, which has been mounted on rotor shaft. 2) It is a kind of vector controls that can produce torque quickly, efficiently and/or precisely. 3) It has wide driving-range and allows developing EVs with no variable transmission. This paper proposes a total of new drive control technologies for such EVs using a permanent-magnet synchronous motor as a main motor, and verifies its usefulness through development of an actual EV that can drive on public road.
This paper describes a dynamic response analysis of a laser marker which has an eddy current damping mechanism. In this calculation the equation of magnetic field is coupled with the equation of motion employing the 3-D finite element method (FEM), and time variations of the pendulum are computed to estimate the damping time. The usefulness of the computation is clarified through the comparison with the measured results. Moreover, the effectiveness of proposed damping structures is also confirmed by the comparison with the conventional one.
The single-phase three-wire distribution system is employed extensively in Japan and the several countries. It has two voltage sources, which are in phase and have the same effective values. Numerous loads are connected to this distribution system. System line currents from two sources tend to be out of balance, because consumers make use of these loads at random. If many working loads lean to a one-sided source, the power interruption will occur by the operation of circuit breakers. For preventing the above trouble, we propose a novel Current Balancer. It consists of two half-bridge converters composed of an ac reactor and two bidirectional switching devices in common with a neutral line and two dc capacitors. In this paper, it is made clear that the proposed system can equalize both source currents even if the load currents are unbalanced. Moreover, we discuss the several characteristics in steady state and transient state by simulations and experiments.
This paper deals with a dynamic voltage restorer (DVR) characterized by installing the shunt converter at the load side. The DVR can compensate for the load voltage when a voltage sag appears in the supply voltage. An existing DVR requires a large capacitor bank or other energy-storage elements such as double-layer capacitors or batteries. The DVR presented in this paper requires only a small dc capacitor intended for smoothing the dc-link voltage. Moreover, three control methods for the series converter are compared and discussed to reduce the series-converter rating, paying attention to the zero-sequence voltages included in the supply voltage and the compensating voltage. Experimental results obtained from a 200-V, 5-kW laboratory system are shown to verify the viability of the system configuration and the control methods.