Sakutaro Nonaka

A novel three-phase sinusoidal PWM voltage source inverter and its application for photovoltaic power generation system

In this paper, a novel three-phase sinusoidal PWM voltage source inverter (VSI) is proposed. The inverter has an additional arm to the normal PWM three-phase bridge circuit. The additional arm contributes to reduce the ripple in the AC output current. As an example of the application of this VSI, a utility-connected photovoltaic power generation system is shown. In the system, smooth DC current without pulsation is supplied from a PV array, and the VSI provides sinusoidal AC current for domestic loads and the utility line.

Current regulated PWM-CSI induction motor drive system without a speed sensor

A current source inverter (CSI)-induction motor drive system without a speed sensor is considered. An input DC link current which is kept constant by a pulse-width-modulated converter with sinusoidal input current is supplied in the PWM inverter. The inverter output current with sinusoidal wave is directly regulated by employing the modulation index control of the PWM strategy. Experiments show that high-performance steady-state behavior and acceleration/deceleration characteristics with smooth drives and low noise of the motor have been obtained. It is demonstrated that the system with only the current sensor has the same steady-state and transient characteristics as the system with the voltage and the current sensors.<<ETX>>

FFT analysis of the composite PWM voltage source inverter

This paper describes a FFT analysis of the composite PWM voltage source inverter (VSI). The VSI has the normal single-phase bridge circuit and an additional arm. The composite PWM method contributes to reduce the ripple in the AC output current. The VSI has a LC series-resonance circuit tuned to twice the utility frequency connected in parallel with the smoothing capacitor Also, the smoothing capacitor is drastically reduced The smooth DC current is obtained by using the resonance circuit tuned to twice the AC source frequency.

Single-phase PWM current source converter with double-frequency parallel resonance circuit for DC smoothing

A single-phase PWM (pulse-width-modulated) current source power converter with a sinusoidal input current is considered. To smooth the DC current in the reduced DC inductance, an LC parallel resonance circuit (tank circuit) is inserted in the DC side of the converter. The proposed converter can supply the constant DC current to a load. Experimental and analysis results show that the tank circuit contributes to the achievement of the smoothing DC current and the decrease of the DC inductance. The steady-state and the transient characteristics of the converter are given.<<ETX>>

Single-phase composite PWM voltage source converter

This paper proposes a novel circuit of a single-phase voltage source converter. A pulsewidth modulation (PWM) strategy is utilized to obtain a sinusoidal input current. The proposed circuit has an auxiliary arm for the bridge circuit and can be operated by a composite PWM strategy which contributes to reduce the ripple in the current. Moreover, the novel circuit has an LC series resonance circuit in the DC side. The DC capacitance necessarily installed in the converter can be greatly reduced by applying the resonance circuit and the constant DC voltage is achieved. The experimental and the theoretical results in the rectifier operation of the converter are shown. The steady state waveforms in the inverter operation with the photovoltaic in the DC side are given. The experiments show that the proposed converter can be used for a single-phase utility interactive photovoltaic system.<<ETX>>

A utility-connected residential PV system adapted a novel single-phase composite PWM voltage source inverter

An electric utility-interactive residential PV power system adapted novel single-phase composite PWM voltage source inverter (VSI) is proposed. The proposed system is equipped with PV array, battery storage, and a single-phase VSI, which has a new circuit configuration and PWM method. The VSI circuit consists of the normal single-phase bridge circuit and an additional arm. The two auxiliary self-turn-off devices of the arm avail to adopt a composite PWM control, which contributes to reduce the ripple in the AC output current. Also, the VSI has a LC series resonance circuit tuned to twice the utility frequency connected in parallel with the smoothing capacitor. The series resonance circuit absorbs the double-frequency AC components included in the DC pulsated current. Consequently, the smoothing capacitor is drastically reduced. It was found by computer simulation and experiment that the waveform of AC output current shows an ideal sine wave.

A suitable single-phase PWM current source inverter for utility connected residential PV system

Abstract A suitable single-phase inverter for the utility connected residential photovoltaic generation system is proposed. The proposed single-phase PWM current source inverter (CSI) has an additional branch to the normal single-phase bridge circuit. The auxiliary switches avail to adopt the composite PWM control, and a double frequency parallel resonance circuit (LC tank circuit) is inserted in the DC side of the inverter in order to reduce the size and weight of the DC reactor. The smooth DC current without pulsation is supplied from PV array, and the inverter provides a sinusoidal AC current for domestic loads and the utility line. In the system, the PV array can play an important role as a current-limiter by its V - I characteristics.

Analysis of new brushless self-excited single-phase synchronous generator by finite element method

An analysis of a novel brushless self-excited single-phase generator is presented. The rotor of the generator consists of a short-circuited field coil with a diode. The output voltage can be near constant for a wide range of load without AVR. In order to establish the design criterion of this generator, a magnetic field analysis is carried out. It is found that the theoretical results agree with the experimental ones. This generator is very simple, robust and maintenance-free. It is useful as a maintenance-free constant-speed generator.<<ETX>>

Application of utility interactive photovoltaic power generation system for UPS

Abstract The paper proposes the application of PV system for uninterruptible power supply (UPS). The PV system is composed of a novel single-phase PWM voltage source inverter (VSI). Composite PWM method is achieved by a circuit configuration consisting of the normal single-phase bridge circuit and an additional arm, which contributes to reduce the ripple in the AC output current. The VSI has a LC series-resonance circuit tuned to twice the utility frequency connected in parallel with the smoothing capacitor. The series-resonance circuit absorbs the double-frequency AC components included in the DC pulsated current. Hence, the smoothing capacitor is drastically reduced. A storage battery is added on the DC side in order to stabilize DC voltage. The VSI is easily changed from inverter action to rectifier action by changing the firing angle α from plus to minus. When α is minus, the VSI acts as a battery charger.

A new brushless excitation method for 4-pole three-phase synchronous generator with cylindrical-rotor

For a 4-pole three-phase synchronous generator with cylindrical-rotor, a new brushless excitation method is proposed. The stator of the generator is provided with a 4-pole three-phase main winding and a 6-pole single-phase exciting winding. The generator has a nonsalient-pole rotor. The field winding is a distributed winding placed in slots and arranged so as to produce an approximately sinusoidal 4-pole field. When the 6-pole stator exciting winding is excited by DC current, the AC voltage is induced in each rotor field coil. The rotor field coils are connected with diodes, respectively, so as to make the same 4-pole magnetic field as the stator main winding. The each field coil consists of a half-wave rectification circuit. The rotor field excitation is controlled proportionally by the stator DC exciting current. By this scheme a brushless 4-pole three-phase synchronous generator without exciter has been achieved. In the paper the operating principle and the circuit configuration of the generator are described in detail, and experimental results using a 2 kVA prototype machine are shown.<<ETX>>