Toshimitsu Morizane

Wind Power Generation System with Induction Machine and Diode Rectifier

This paper investigates advantages of new combination of the induction generator for wind power and the power electronic equipments. Induction generator is popularly used for the wind power generation. The disadvantage of it is impossible to generate power at the lower rotor speed than the synchronous speed. To compensate this disadvantage, expensive synchronous generator with the permanent magnets sometimes used. If HVDC transmission is used to connect the offshore wind farm to the mainland, using AC/DC converter system is no more disadvantageous. However, to omit the expensive permanent magnet is desirable. In proposed scheme, the diode rectifier is used to convert the real power from the induction generator to the intermediate DC voltage, while the reactive power necessary to excite the induction generator only is supplied from the voltage source converter (VSC). This means that the rating of the expensive VSC is minimized and total cost of the wind power generation system is decreased compared to the system with synchronous generator

Control of Traction and Levitation of Linear Induction Motor Driven by Power Source With Frequency Component Synchronous With the Motor Speed

Linear Induction Motor (LIM) has many applications. The maglev transportation system is the most popular application. The typical maglev transportation system has the traction system and levitation system separately. The LIM is used for the traction system. The levitation magnets are implemented as the levitation system. We have developed a novel maglev system using the LIM without the levitation components. In this system, the attractive force of the LIM can be used for the levitation control. In this paper, we propose the novel control method of the thrust force and the attractive force of LIM driven by the power source with the frequency component synchronous with the motor speed. In this control method, it is possible to apply the conventional vector control to the thrust force control of LIM. The frequency component synchronous with the motor speed does not generate the thrust force. Therefore the frequency component synchronous with the motor speed is able to adjust the attractive force for the levitation without the influence on the thrust force control. The controller becomes simpler by the proposed control method. We design the controller for the proposed maglev system. The simulation results show the traction and levitation control of LIM are achieved by the proposed control method.

Control of PFC converter with inverter excited induction generator for advanced wind power generation system

This paper shows new induction generation system for wind power generation. This system has inverter excited induction generator and the PFC converter to transfer the real power. Simulation and experimental results certifies that the DC/DC chopper control of the PFC converter can minimize the inverter current, which only supplies exciting current for the induction generator. It is also shown that the harmonic components of the current from the inverter is suppressed by the active filter action in the output voltage control of the inverter.

Active filter action of inverter exciting induction generator for wind power generation

This paper shows new induction generation system for wind power generation. This system has the voltage source converter (VSC) exciting induction generator and the PFC converter to transfer the real power. Rated power of the VSC is minimized by transferring all the real power into the PFC converter. However, the harmonic components in the current from the VSC has larger peak than expected for the fundamental component. Therefore, active filter action to eliminate these harmonic components in the current from the VSC is investigated in this paper. Simulation results show the reduction rate of 1/5 of harmonic components by the active filter action.

New real time symmetrical coordinate transformation using complex number calculation to detect imbalanced fault in utility power system

This paper proposes a real time symmetrical coordinate transformation applied for detection of imbalanced fault in utility power system. The power conditioner of the photovoltaic system in Japan is required to remain connected when the utility power system fault occurs under certain condition. The most popular fault is 1 line-to-ground fault. The next is 2 line-short fault. Both cause the imbalance voltages and currents in 3-phase power system. To optimize the output from the power conditioner of the photovoltaic system, the detection of the imbalanced condition is important factor. In this paper, new development of the signal processing method by using the complex number algebra in real time system is shown. The fast detection of the imbalanced condition is verified by the computer simulations. It is also verified by the experiments that the calculation of proposed method can be done fast enough by using the digital signal processor.

Real time symmetrical coordinate transformation applied for detection of imbalanced fault in utility power system

This paper has investigated the possibility of a real time symmetrical coordinate transformation. Simulation is performed when it is applied for detection of imbalanced fault in utility power system. The power conditioner is required to remain connected when the fault occurs in the utility power system under certain condition. This is called as the fault ride through (FRT) ability. The most popular fault is 1 line-to-ground fault. This fault causes the imbalance voltages and currents in 3-phase power system. To optimize the output from the power conditioner of the photovoltaic system, the detection of the imbalanced condition is important factor. In this paper, the signal processing method by using the complex number algebra in real time system is shown at first. The fast detection of the imbalanced condition is verified by the computer simulations. Then the effects of the harmonic components existing in the system voltage have been investigated. The generation of the offset output and the oscillating waveforms are indicated.

Single to two-phase matrix converter using GaN-based monolithic bidirectional switch for driving symmetrical two-phase motor

In this paper, we present a single to independent two-phase matrix converter (iS2MC) consisting of eight Gallium Nitride (GaN) based monolithic bidirectional switches for the first time. The modulation algorithm for the switches in the iS2MC was designed more easily than that in the three-phase matrix converter. So far, common emitter back-to-back Insulated Gate Bipolar Transistor (IGBT) configuration was used for one bidirectional switch in the conventional iS2MC to drive a symmetric two-phase induction motor. The GaN based bidirectional switches have high breakdown voltage and low specific on-state resistance. The experimental results show that the power conversion efficiency of the GaN-based iS2MC is higher than that of the IGBT-based iS2MC for all the conditions and 7.2 % higher at maximum.

Characteristics of forces of Linear Induction Motor driven by power source including frequency component synchronous with the motor speed

We have proposed the Linear Induction Motor (LIM) is driven by the power source including different frequency components to control the attractive force and thrust force. In this paper, we propose the frequency component synchronous with the motor speed is used as one of the components. It achieves the easy control of the forces because the component synchronous with the motor speed generates only the attractive force. We verify the characteristics of the attractive force and thrust force by the experiment.

Inverter excited induction machine for high performance wind power generation system

This paper investigates new system configuration of induction generator for wind power generation. Proposed system realizes the variable speed generation with small capacity of inverter by using PFC converter with a diode rectifier and a boost chopper as the active power converter. The inverter supplies the reactive power only for the induction generator. The reduction of the capacity of the inverter leads to the lower system cost. It is also advantageous that the dc side of the rectifier is connected to the dc transmission line and the dc battery charger to reduce the total cost by omitting the inverter to connect to the utility system. Simulation results show that the capacity of the inverter is reduced to almost 1/5 of full rating. It is also shown that the duty factor of the boost chopper of the PFC converter can control the active power of the PFC converter and the inverter simultaneously.

A novel single to two-phase matrix converter for driving a symmetrically designed two-phase induction motor

We propose a novel single to two-phase matrix converter (iS2MC) for driving a symmetrical two-phase induction motor. Matrix converter (MC) technology is already used in industrial applications, but is limited to three-phase induction motor with three-phase power line. The iS2MC, which consists of 8 bi-directional switches, enables a two-phase induction motor to be driven by single-phase power line without smoothing capacitors for the first time. The iS2MC generates independent two-phase voltages controlled by a simple switching algorithm, which is designed to hold the switching state for a period of the output source to decrease switching loss. The two-phase motor driven by iS2MC eliminates start-run capacitors and generates more torque than the three-phase motor. The performance of the iS2MC system with symmetrical two-phase induction motor was confirmed by both simulation and experiment.