We developed networks for flow and temperature circuits using OpenModelica to calculate the temperature of rotating electrical machines. Air temperature and volume were calculated using a model constructed for a diesel engine generator and compared with the measured results. As for the results; (1) An error of 7% was obtained in the calculation of the ventilation network by comparing the static pressure measurement with that of the calculation; (2) The temperature distribution of the stator coils matched that of the temperature measurements, when using the thermal network. Furthermore, the temperature rise of the refrigerant was reflected in the stator coils; (3) Comparing the temperature measurement by the resistance method and the calculated average temperature, it was confirmed that the highest exfoliation temperature was 6.3 K in the stator coil of the copper loss test; (4) OpenModelica can be used to calculate the ventilation and temperature networks of a rotating electrical machine, and the solution can be obtained promptly.

A dielectric barrier discharge load (DBD) with a maintenance voltage of 1.5kV has been successfully driven stably from a 48V inverter only by resonance voltage boost and no transformer. The proposed circuit consists of a two-stage resonant circuit. The circuit operation is investigated using both prototyping measurement and circuit simulation, which shows that despite the high Q value, the design margin and operating stability of the circuit are extremely wide. It is found that this operational stability can be explained by considering the impedance characteristics of DBD. We believe that the circuit is suitable for driving discharge loads such as DBD in practical applications.

In high-speed surface permanent-magnet motors, eddy current loss in the rotor caused by magnetic flux harmonics is a significant problem. Although copper sleeves can reduce the eddy current loss of the rotor, the reduction effect on each eddy current harmonic component is not clear. In this paper, we calculate the eddy current loss in the rotor using finite element analysis, divide the losses into each harmonic magnetic flux component, and analyze the influence of copper sleeve on each harmonic component. Based on the knowledge obtained in the analysis, we propose the use of copper sleeve with holes as a method for reducing rotor loss further. The effect of the proposed method is verified using electromagnetic simulation.

This paper proposes a gain-scheduling control method to stabilize the slewing angular velocity even with variations in crane boom length and perturbations in the controlled-plant model. The model used in the proposed gain-scheduling control system is identified through experiments on an actual crane, and are derived under three boom length conditions. Specifically, the model is expressed as the sum of four vibration modes and a time delay, and its parameters are identified. By linearly interpolating the three models, the gain of a type-one control system including an observer is designed for each 0.5m boom length, after considering the time delay. The proposed gain-scheduling control is realized by selectively applying these gains according to the boom length. In an experiment to verify the effectiveness of the proposed method, a step reference was input for the slewing angular velocity while extending the boom length, and its time response was compared to that of a single controller designed for a boom length of 20m (midpoint). The experimental results showed that the time response of the single controller deteriorated when the boom length of the crane was extended, especially beyond 20m, while the proposed method was able to stably control the slewing angular velocity of the crane even when the boom length reached 30m.

This paper proposes a cooperation framework of the optimal operational planning of an energy plant and optimal production scheduling in factories using an improved integer form of adaptive population-based incremental learning (IIAPBIL) and a production simulator. Traditionally, the optimal operation planning of energy plants has been solved using various tertiary energy fixed loads. In addition, for production lines, researches have recently been conducted to optimize production planning considering energy consumption reduction in addition to minimizing production time. However, the research scope has been restricted to the demand side. Therefore, it was not possible to accurately reduce the secondary energy costs of a factory. In this paper, using the production simulator and the proposed optimization method, the tertiary energy load for each candidate production plan is calculated. Subsequently, the optimal operation plan for the energy plant using the tertiary energy is determined and the total costs of the entire supply and demand operation are calculated and evaluated. Therefore, the secondary energy cost of the plant can be explicitly reduced. The proposed IIAPBIL and the conventional integer form of APBIL (IAPBIL) are applied to a production cost minimization problem of an assembly line and an energy plant, respectively. As a result, it is confirmed that both demand-side and supply-side costs can be minimized simultaneously, and the best quality solution can be obtained using the proposed IIAPBIL. Moreover, high-speed computation can be achieved using the parallel and distributed processing simulator.

Five-axis passively stabilized bearingless motors with diamagnetic materials have notable advantages as they do not require displacement sensors and suspension powers for static magnetic suspension. A diamagnetic pyrolytic graphite rotor is passively levitated and actively rotated. In previous studies, the principle of passive levitation force generation has been proposed and experimentally verified. In this paper, the torque generation principle of the diamagnetic bearingless motor is derived, and the rotating torque is estimated in deceleration and acceleration tests.

This paper proposes an AC/DC converter for an air-conditioning motor drive system and a PFC converter capable of controlling the harmonics of the supply current by feeding back the harmonic component of the supply current. We aim to improve the efficiency of the PFC converter by performing switching pauses at peak DC voltage periods. Our proposed method has an online feedback system that calculates harmonics and THD of the power supply current and a model predictive control of the reactor current, thereby enabling current-control corresponding to discontinuous control changes within one power supply cycle, including switching pauses. This enables appropriate harmonic control.