IEEJ Journal of Industry Applications Vol. 6(2017) No. 5

This paper proposes a voltage-rise-suppression strategy with a power quality compensator for a roof-top home solar power system (HSPS) connected to the point of common coupling (PCC) in single-phase three-wire distribution feeders (SPTWDFs). The proposed reactive power control and power quality compensation strategy uses only a constant dc-capacitor voltage control, which is always used in grid-connected inverters. No calculation blocks of the reactive and unbalanced active components of the load currents are necessary. Thus, the authors provide the simplest algorithm to suppress the voltage rise at the PCC with power quality compensation. The basic principle of the constant dc-capacitor voltage-control-based strategy is discussed in detail. The instantaneous power flowing into the HSPSs shows that the predefined power factor of 0.9, a value that conforms to the Japanese regulations, is achieved with improved-quality source-currents of domestic consumers connected to SPTWDFs, suppressing the voltage rise at the PCC. A digital computer simulation is implemented to confirm the validity and high practicability of the proposed control algorithm for HSPSs using a typical SPTWDF model in Japan. Simulation results demonstrate that the proposed control method for the roof-top HSPS suppresses the voltage rise at the PCC, improving the source-side power quality.

This paper proposes a fast and robust nonlinear deadbeat control for boost DC-DC converters. First, the nonlinear state equation is derived, and second a nonlinear current reference deadbeat control is proposed. Third, a new nonlinear controller to implement the load disturbance compensation is proposed. After the simulations and verification by experiments, it was confirmed that under the conditions of an input voltage of 12V, an output voltage of 20V, a load resistance of 4Ω and a sampling frequency of 100kHz, the voltage command tracking capability of a settling time of 280µs was achieved, and an output voltage recovery time of 1.46ms was achieved for a sudden load change.

Electro-hydrostatic actuators (EHAs) are hydraulic actuators with high power-to-weight ratios that exhibit low energy loss. Thus far, methods for determining the characteristics and parameters of EHAs have not been fully established. Therefore, modeling methods for EHA are in demand. EHAs are driven by servomotors on the motor-side and hydraulic motors on the load-side, and therefore, the actuators are expected to experience sympathetic vibrations. Thus, EHAs can be considered as systems in which two rigid objects are connected to one another with a low-rigidity shaft such as a spring. The occurrence of resonance in EHAs has not yet been discussed because of difficulties with hydraulic systems. One major problem is the large friction in hydraulic motors. We apply a feedback modulator for friction compensation to enable the experimental identification of characteristics. Assuming that EHAs experience two-inertia resonance, the parameters of the motors can be calculated. In addition, vibration-suppression techniques for two-inertia systems can be applied to EHAs. This study proposes the application of a two-inertia model to suppress vibrations in EHAs and verify their dynamic characteristics.

In recent years, inductive power transfer (IPT) systems have been actively studied. This paper describes the development trend of inductive power transfer systems since the 1970s, focusing on the transmission frequency, transmission power, and the coupling coefficient, on the basis of a survey of papers published by IEEJ and IEEE. The transmission power shows close correlation with the transmission frequency. By contrast, the coupling coefficient does not show correlation with either the transmission frequency or the transmission power.