Katsunori Taniguchi

PWM technique for power MOSFET inverter

A sinusoidal PWM (pulsewidth-modulated) inverter suitable for use with power MOSFETs is described. The output waveforms in the proposed PWM inverter are investigated both theoretically and experimentally. A modulating signal for the three-phase PWM inverter is obtained by adding the harmonic components of integer multiples of three to the three-phase sine waves. By using the proposed modulating signal, the amplitude of the fundamental component is increased about 15% more than that of a conventional sine-wave inverter and the commutation number of the inverter is decreased to two-thirds of a conventional one. >

Trapezoidal Modulating Signal for Three-Phase PWM Inverter

Trapezoidal wave is suitable for the modulating signal of the microcomputer-based pulsewidth modulation (PWM) inverter for the use of motor drives because the switching patterns can be generated by means of on-line computation. The waveform is changed from a rectangular to a triangular wave.

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

Analysis and improvement of input current waveforms for discontinuous-mode boost converter with unity power factor

A boost converter is widely used for power factor correction (PFC). The discontinuous mode (DCM) converter eliminates the complicated circuit control requirement, reduces the number of components, and reduces the filter reactive components size. Analysis of an input current waveform of the DCM boost converter is described in this paper. The components included in the input current waveform are fundamental plus third harmonics and other components can be neglected. An input current waveform improvement method is also proposed.

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.

The power factor control system of photovoltaic power generation system

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.

A PAM inverter system for vector control of induction motor

A new PAM method to reduce the torque ripple in an induction motor without producing an optional pulsating wave in a DC link is proposed. A modulating signal has a flat portion of 120-degrees. By using the proposed modulating signal, the amplitude of the fundamental component is increased to about 17 percent more than that of a conventional sinewave inverter; the switching loss is decreased and the motor driven by the PAM inverter produces approximately constant torque.<<ETX>>

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.

Suppression of harmonics of multi-level converter applied for back-to-back HVDC link

Multilevel converter is suitable for high power application and is able to reduce harmonics while keeping switching frequency at the fundamental frequency. We propose to apply multilevel converter configuration for back-to-back HVDC link to suppress harmonics without multi-pulse PWM method which introduces large switching loss. In this paper, 9, 11 and 13 level converters are described and compared from the point of harmonic reduction. Theoretically, 9-level can suppress 5th, 7th and 11th harmonics, however 11-level cannot suppress 5th, 7th, 11th and 13th harmonics and 13-level is required.

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.