The motion of an ion cloud which is produced by a corona discharge with a high voltage pulse of a short duration and is introduced into parallel plate electrodes is calculated numerically. The ion cloud initially placed at the tip of a needle electrode is simulated by a number of ring charges and the trajectories of individual ring charges are calculated by using electric field strength obtained with a charge simulation method. Not only movement of the ion cloud but also the waveform of the induced current flowing through a ring electrode located at the center of the parallel plate electrode are simulated and analyzed. The ion cloud with an initial diameter of 0.5 mm expands to 5 mm by electrostatic repulsion within 10 /spl mu/s after the beginning of drift. During drifting toward the counter electrode. The ion cloud extends wider to around the diameter of around 20 to 25 mm. The size and velocity of ion clouds agree with those estimated by experiments and the waveform of induced current obtained by experiments is reproduced by this simulation.< >
The motion of an ion cloud which is produced by a corona discharge with the high-voltage pulse of a short duration and is introduced into parallel plate electrodes was calculated numerically. The ion cloud initially placed at the tip of a needle electrode was simulated by a number of ring charges and the trajectories of individual ring charges were calculated by using electric field strength obtained with a charge simulation method. Not only movement of the ion cloud but also the waveform of the induced current flowing through a ring electrode located at the center of the parallel plate electrode were simulated and analyzed. The ion cloud with an initial diameter of 0.5 mm expands to 5 mm by electrostatic repulsion within 10 /spl mu/s after the beginning of drift. During drifting toward the counter electrode, the ion cloud extends wider to a diameter of around 20-25 mm. The size and velocity of ion clouds agree with those estimated by experiments and the waveform of induced current obtained by experiments was reproduced by this simulation.
Since the elongated particles have experimentally shown better ER effect than spherical ones, chain formation mechanism of suspensions was investigated by using a large scale model. In series of the experiment with this large scale model, interesting and peculiar particle motions were observed. Experimental set up consists of parallel electrodes immersed in Silicone fluid whose conductivity was changed by adding butylalcohol. The motion of propylene rod with a diameter of 0.7 mm and 6 mm long was examined by using video camera and also high-speed camera. At very low conductivity, there is no motion of the rod. When the conductivity is increased, there is many different kind of motion observed. Rotational motion was most frequently observed at a certain range of conductivity. Further increase of applied field, there is a circular motion of the rod. The rotational speed increases with the applied field. However, when the circular motion starts, the rotational speed decreases. The highest rotational speed observed was 11 rps.
The vibration phenomenon occurring under indirect field oriented control or vector control when induction motors drive an inertia load through a spring under overload conditions at high speed is described. The vibration mechanism is clarified, and a suppression method is proposed. The subject of this study is a hybrid vehicle consisting of a front engine-driven system and two rear motor-driven systems, which are designed to improve the driving stability. A stability analysis of the total system, including a vector control system and a mechanical system, reveals that the vector control system is essentially unstable under extreme overload and demagnetization conditions, even if the motor is perfectly controlled. Therefore, suppression of vibrations was attempted using an observer for estimating wheel torque and a regulator for state feedback from the outside of the vector control system. These methods perfectly suppressed the vibration, realizing a compact, light motor-driven system with rapid, stable performance.< >
The motion of a filamentary particle and also the discharge from a particle have been extensively investigated for the development of a prevention and protection method against breakdown in gas-insulated switchgear. The particle showed several different patterns of motion, e.g., "standing," precession motion, oscillating up and down, etc. Each of these types of motion depends on corona discharge from the particle itself. Since this motion cannot be explained only by monopolar discharge from one end of a particle, bipolar discharge from both ends of a particle occurring simultaneously has been investigated by applying the floating particle method. The particle length and the gap between the particle and electrode were chosen as parameters. From experimental results, several interesting features were obtained. The curve of bipolar corona. current lies between negative and positive corona currents of monopolar curves. There is a sudden current increase at the threshold voltage that seems to be a new feature of the corona current from a filamentary particle. So far, the experimental results indicate that this threshold voltage is not a function of particle length, but it could depend slightly on length. Flashover voltage is a function of particle length and the gap. It decreases with length and increases with the gap.
In this paper, latest motor drive technologies used for hybrid vehicles (HV), which are high output motor control and variable voltage system, will be introduced. Authors have researched and developed motor drive technologies through development of hybrid vehicles, which has been put into practical use to production vehicle. The developed motor drive system has the features of high efficiency, high power/weight ratio, and low-cost.
In order to clarify the mechanism of a discharge occurring between a space charge cloud and a grounded object, the formation of a space charge cloud with highly charged droplets and the characteristics of the corona discharge occurring from a grounded electrode in the cloud have been investigated. The droplets sprayed from an airless nozzle were charged by induction charging and transported by additional air flow. A grounded electrode was inserted into the charged droplets cloud to cause a discharge in the cloud. The faster the velocity of the charged droplets transported by the air flow, the larger is the charge quantity of droplets. The magnitude of the corona discharge depends on the charge density of the cloud and the size of the grounded electrode. The maximum pulse height of the corona discharge was 50 mA in the negatively charged droplets cloud.
