Akiteru Ueda

A method of current detection for an active power filter applying moving average to pq-theory

The accuracy of harmonic currents detector and characteristics of current controls are important to improve the compensation characteristics of an active power filter. This paper proposes a detector which has high accuracy and good response by applying pq-theory and moving average high-pass-filter (HPF) and good response current control by applying current-deviation code-distinction. A new modified detection system using a moving average HPF whose sampling time is changed according to the source frequency fluctuation is also proposed. The active power filter combining the proposed method of the detector and the current control can compensate harmonic currents which are generated by a three-phase rectifier with a DC filter capacitor with high accuracy and good response.

AC chopper using four switches

Several circuits were proposed as methods for adjusting AC power. In this paper, the authors propose an AC chopper circuit with four switches and examine the fundamental character of the circuit. It has a simple configuration and excellent performance. The DC snubber can be used by dividing an input filter capacitor into two parts. The proposed circuit has high efficiency for adjusting AC power, because it is composed of fewer switches and DC snubbers.

Study of AC/DC power supply system with DGs using parallel processing method

This paper proposes a new AC/DC power supply system with DGs using the parallel processing method. The purpose of this system is to supply the power without connecting to the utility gird. The DGs consist of photovoltaic (PV) and wind generators (WG), and the main energy source of this system is the DGs and the UPS battery. When the system does not get enough energy from the DGs, and the power supply of the battery runs out, this system connects to the utility grid and begins to charge the battery and supply to the load. In this study, we focused on the AC power supply and DC power supply from DGs. Then, the converter of DGs uses two kinds of DC/DC type and DC/AC type. Also, the load uses two kinds of DC load and AC load. The proposed the power system has been operated with the actual loads of 20 kW in the campus of the Aichi Institute of Technology.

Motion analysis of a micro-actuator using three piezoelectric actuators

Displacement of a micro-actuator is described theoretically and experimentally. The actuator uses three stacked-type piezoelectric actuators which are connected in an equilateral triangle, and three electromagnets which are attached at all the vertexes of the triangle. The actuator, which can realize a precise motion, is developed for a flexible conveying system, such a desktop manufacturing system. The actuator is used in a micro/nano system which requires a nanometer resolution with multi degrees of freedom. The displacement of the actuator is simulated and demonstrated experimentally

Boost type three-phase diode rectifier using current resonant switch

This paper proposes a boost type single switching device three-phase diode rectifier with a current resonant switch to decrease switching loss and the total harmonic distortion (THD) of the input current. It is confirmed that a switching device in the proposed circuit operates in zero current switching by simulation. This paper also shows that the proposed circuit can decrease the THD of the input current and can improve the input current waveform compared with the conventional boost type single switching device three-phase diode rectifier.

An xy/spl theta/ actuator using piezoelectric and electromagnetic actuators

Microactuators with a micro tool and a micro sensor can provide a lot of benefits to precise engineering. Precise positioning is needed in precision engineering. A system with multi degrees of freedom is required for industrial application. A system with multi degrees of freedom is composed of some systems with one degree of freedom. Therefore, the system becomes complicated and large. We propose a new actuator which can move in x, y and /spl theta/ directions by the extension of piezoelectric actuators and the adhesion of electromagnetic actuators. The proposed actuator realizes high resolution by using the piezoelectric actuator. We describe the structure and principle of the proposed actuator. In order to demonstrate the proposed actuator, we constructed the actuator and measured the velocity in x and /spl theta/ direction. The measured fastest velocity in x direction was 190 /spl mu/m/s and that in /spl theta/ direction was 9.5 mrad/s. The resolution in x direction was obtained to be 0.24 /spl mu/m and that in /spl theta/ direction was 0.1 mrad. We are now improving the resolution of the proposed actuator.

Analysis of a Three-Phase Buck-Boost AC Chopper Controlled in Two Phases

We propose a three-phase buck-boost AC chopper controlled by two phases. Characteristics of the circuit are analyzed by the simulation considering the dissipation of semiconductor devices and inductors. Ripple and total harmonic distortion (THD) of an input current and an output voltage increase when inductive components increase in the load. Variations appear in each phase in buck-boost ratio. The resonance frequency is changed due to the inductive components in the load. The pi-connected output filter is analyzed, and it operates as the second reverse L-connected output filter. THDs in the output voltages are improved when the capacitance in the output filter is changed to adjust the resonance frequency of the output circuit. The three-phase four-wire system is analyzed, and the circuit is compared with the two phases control method. Then, the cause of unbalance at each phase for the three-wire systems is proved to be the two phase control method.

A new method for separating AC component of instantaneous real power and imaginary power suitable for active filters

In a control system of active filters, p-q theory can be used for the calculation of higher harmonic currents. A high-pass filter of the first order is usually used for separating the AC components of instantaneous real power (p) and instantaneous imaginary power (q). However, in such a system the transient response for a load change is not high enough. Here, the authors propose a new control system in which the AC components are derived from p and q using a moving average value calculation method. By the proposed system, control response and accuracy are very good-even in the case of an abrupt load change.

Delta-type miniature robot using levitation mechanisms

We study miniature robots using piezo actuators. We proposed a levitating type miniature robot and a delta-type miniature robot using piezos and electromagnets. We thought that friction force control using levitation mechanism can realize more precise operation, and we proposed delta-type miniature robot using levitation mechanisms. This robot is combined the advantages of the two robots. This robot has three levitation mechanisms using the squeeze film effect. It can realize the linear and rotational displacement by its delta-type structure. Furthermore, its levitation mechanisms can help to decrease the frictional wear between the robot and working surface. In this study, we produce experimentally the L-type miniature robot using levitation mechanisms. This robot also can realize the linear and rotational displacement, and reduce a using piezo.

Ultra fast response control system for active power filter

We have proposed a control system in which AC components are derived from instantaneous real power (p) and instantaneous imaginary power (q) by a moving average high-pass filter. The response and accuracy of the system are very good in the case of an abrupt load change. In this paper, a new control system having an ultra high speed response is proposed for compensating a reactor input type rectifier. The system adopts a new current detection method responding in one sampling period. The operating performance of the proposed system is confirmed by simulation and laboratory model tests.