Kang-Hoon Koh

Fuzzy-Logic-Based

Since natural distribution power generation systems such as wind energy contain electric power fluctuation, flywheel energy storage (FWES) equipment for power compensation is used. Fuzzy-logic-based V/f control of the induction motor is proposed for the speed sensorless power-leveling system in this paper. Only two sensors, including one DC voltage sensor and one DC current sensor, are utilized. The flywheel is composed of two modes, namely, the speed picking-up control mode and the power control mode. According to the DC-link average current of an inverter, the rotating speed of the flywheel in the speed picking-up control mode is detected by regulating the output frequency and the output voltage based on fuzzy logic control. The power control mode consists of the outer voltage loop and the inner current loop. Although the outer loop is also realized by fuzzy logic control, the inner loop is the key object in this paper, i.e., the proportional and integral gains of a proportional-integral regulator are optimized by means of fuzzy logic reasoning for the purpose of the reliability and rapid response of leveling power. The experiments are carried out with the FWES equipment of 40-kJ energy, and the results verify that the proposed method is reliable, and better dynamic and static performance is demonstrated.

V/f

The photovoltaic power generation system has a great future as clean energy instead of fossil fuel, which has many environmental problems such as exhausted gas or air pollution. In a utility interactive photovoltaic generation system, a three phase inverter is used for the connection between the photovoltaic array and the utility. This paper presents a three phase inverter for photovoltaic power system with current controller, voltage controller, PLL control system and the phase detector of interactive voltage by using dq transformation. The proposed inverter system provides a sinusoidal AC current for domestic loads and the utility line with unity power factor.

Control of an Induction Motor for a DC Grid Power-Leveling System Using Flywheel Energy Storage Equipment

The objective of this paper is to develop a power converter module that charges a battery with solar power, and the design technique at the product level is introduced to realize a compact size and light weight. The main circuit is a buck-boost chopper so that it can cover wide range of charging voltage. The MPPT control is realized by a very simple algorithm of Limit-Cycle MPPT (LCMPPT) proposed by authors previously. All control functions are implemented in digital algorithm and a HITACHI H8 microprocessor is used for the control. In addition to the battery, a load can be directly connected also, which is automatically disconnected in the case of detecting a low voltage condition of the battery. RS-232C port is also available for observing the internal variables such as input/output voltages and currents through a PC. An example of obtained test results showing the relations of output power versus input/output voltages and efficiency are given. The efficiency is about 70-72% in a wide range of output power.

The power factor control system of photovoltaic power generation system

To improve the drawback of LCMPPT(Limit Cycle Maximum Power Point Tracking) controller of the existing two power conversion stages, an advanced MPPT scheme of single power conversion stage is proposed in this paper. This topology is faster on the control speed by means of current control method and the system configuration is simpler. The Authors produce a battery charger by using a cost effective one-chip processor (PIC16F877A) and evaluate another application on the basis of simulation. As a result, the proposed new LCMPPT algorithm is confirmed to be stable and useful.

A solar battery charging module by means of Limit-Cycle MPPT control

In this paper, an optimum method is proposed to realize the turbo 2000 W power for induction heating cooker that makes use of the 900 V/60 A IGBT with decreasing operating voltage of the switching device by making a 220 V, 1500 W inverter through the active clamp quasi-voltage resonant inverter.