Kohji Higuchi

Bio: Kohji Higuchi is an academic researcher from University of Electro-Communications. The author has contributed to research in topics: Digital control & Control theory. The author has an hindex of 10, co-authored 105 publications receiving 434 citations.

Power control of single-phase voltage source inverter for grid-connected photovoltaic systems

Abstract: This paper presents the design and analysis of both the active and reactive power control of a single-phase voltage source inverter (VSI) for grid-connected photovoltaic (PV) system. The proposed method is based on vector control of power by decoupling control of the active and reactive current components to feed the active and reactive power to the grid. The aim of this research is to control power factor at grid, to improve overall efficiency of transferring power of PV to alternate current power conversion into the grid, and to decrease phase current distortion of VSI. In this work, mathematical model of system has presented in details. The results of simulations of PV system 1kW connected to grid 220V, 50 Hz using MATLAB/Simulink software are also discussed. Simulation results have shown that the grid input power factor is nearly unity, and the distorting of phase current of the proposed system has been reduced, causing the total harmonic distortion for various power conditions falls within 5%.

Modelling and Observer-based Sliding-Mode Control of Electronic Throttle Systems

Abstract: With increasing demand for high fuel e‐ciency, better exhaust control measures, comfort and high performance on current automotive vehicles, electronic control of the throttle chamber which decides the engine output, is becomming advanced day by day. It is expected that this trend towards electronic control of the throttle chamber will be maintained in conjunction with injection air-amount control, drive control, traction control, etc. Modelling and control methods for electronic throttle servo systems are proposed, which consist of a DC motor, a throttle valve and a return spring. The control method fulfllls the demand for high robustness in nonlinear opening of the throttle. In this paper, a modelling method of an electronic throttle chamber system is flrst proposed. Next, an observer-based sliding-mode controller with prescribed transient response is designed for the system. By using a function-augmented sliding hyperplane, it is guaranteed that the output tracking error converges to zero in a flnite time. Simulation and experimental results demonstrate the efiectiveness of the sliding-mode controller with prescribed transient response.

A Single-Stage LED Driver Based on ZCDS Class-E Current-Driven Rectifier as a PFC for Street-Lighting Applications

Abstract: This paper presents a light-emitting diode (LED) driver for street-lighting applications that uses a resonant rectifier as a power-factor corrector (PFC). The PFC semistage is based on a zero-current and zero-derivative-switching (ZCDS) Class-E current-driven rectifier, and the LED driver semistage is based on a zero-voltage-switching (ZVS) Class-D LLC resonant converter that is integrated into a single-stage topology. To increase the conduction angle of the bridge-rectifier diodes current and to decrease the current harmonics that are injected in the utility line, the ZCDS Class-E rectifier is placed between the bridge-rectifier and a dc-link capacitor. The ZCDS Class-E rectifier is driven by a high-frequency current source, which is obtained from a square-wave output voltage of the ZVS Class-D LLC resonant converter using a matching network. Additionally, the proposed converter has a soft-switching characteristic that reduces switching losses and switching noise. A prototype for a 150-W LED street light has been developed and tested to evaluate the performance of the proposed approach. The proposed LED driver had a high efficiency (>91%), a high PF (>0.99), and a low total harmonic distortion (THD $_{i}$ ${{V}}_{{\rm{rms}}}$ . These experimental results demonstrate the feasibility of the proposed LED scheme.

Attitude control of a quadrotor aircraft using LQR state feedback controller with full order state observer

Abstract: This paper presents an attitude control scheme that can track the desired Euler angle trajectories The proposed controller is based on an optimization technique designed in the discrete time domain All state variables are estimated using a full-order state observer The simulation results show tracking performance of the designed controller compared with a classical PD controller

Model-free–based terminal SMC of quadrotor attitude and position

Abstract: In this paper, a model-free–based terminal sliding-mode control (MFTSMC) strategy is developed to control the attitude and position of a quadrotor whose model includes parameter variations, uncertainties, and external disturbances. The proposed MFTSMC combines a model-free control approach with a sliding-mode technique and makes possible to eliminate the tracking error in a finite time. To demonstrate the performance and effectiveness of the proposed MFTSMC, numerical simulation results have been obtained and compared with corresponding results for PID, backstepping and sliding-mode controls.

Digital Predictive Current Control of a Three-Phase Four-Leg Inverter

Abstract: While the classical control techniques for three-phase two-level four-leg inverters are based on pulsewidth modulation or 3-D space vector modulation, this paper presents a simple digital current control strategy without the modulation stage. The proposed controller uses the discrete nature of the four-leg inverter and filter to generate the switching states. Using a predictive cost function, the optimal switching state to be applied in the next sampling interval is selected. The proposed controller offers excellent reference tracking with less current harmonic distortion for balanced and unbalanced loading conditions. The feasibility of the proposed strategy is verified by digital implementation on a dSPACE DS1104-based rapid prototype platform.

Control strategies for single-phase grid integration of small-scale renewable energy sources: A review

Abstract: Small-scale renewable energy sources, such as small hydro turbines, roof-mounted photovoltaic and wind generation systems, and commercially available fuel cells are usually connected to the single-phase distribution grid through a voltage source converter To regulate the power exchange with the single-phase grid, and at the same time, reduce the harmonic distortions in the ac current, different current control structures have already been proposed, among which the current hysteresis control, the voltage oriented control, and the proportional-resonant based control have found more attentions This paper provides an overview of the main characteristics of these control strategies Also, some implementation aspects such as the fictitious signal generation and the single-phase grid synchronization techniques are discussed Finally, through extensive simulations a comparative study of the presented control strategies is presented The simulations are supported by experiments

Formation Control With Obstacle Avoidance for a Class of Stochastic Multiagent Systems

Abstract: This paper addresses formation control with obstacle avoidance problem for a class of second-order stochastic nonlinear multiagent systems under directed topology. Different with deterministic multiagent systems, stochastic cases are more practical and challenging because the exogenous disturbances depicted by the Wiener process are considered. In order to achieve control objective, both the leader-follower formation approach and the artificial potential field (APF) method are combined together, where the artificial potential is utilized to solve obstacle avoidance problem. For obtaining good system robustness to the undesired side effects of the artificial potential, $H_\infty$ analysis is implemented. Based on the Lyapunov stability theory, it is proven that control objective can be achieved, of which obstacle avoidance is proven by finding an energy function satisfying that its time derivative is positive. Finally, a numerical simulation is carried out to further demonstrate the effectiveness of the proposed formation schemes.