Y. Konishi

A novel pulse-density-modulated high-frequency inverter for silent-discharge-type ozonizer

This paper presents a novel prototype of a voltage-source load resonant inverter using insulated gate bipolar transistors for driving a silent-discharge-type ozone-generation tube. Ozone-generation technology has a history of more than 100 years and ozonization has been recognized as one of the best methods for water treatment, desinfection, industrial wastes utilization, and so on. However, some technological difficulties related to efficient ozone production and high cost of the ozone-generating equipment have been significant problems restricting ozone usage in the industrial plants. Introduced in this paper is a pulse-density-modulated high-frequency inverter for a silent-discharge-type ozonizer, which is developed with the aim to improve power conversion and control characteristics of the ozone generation by using advances in power electronic technology. The developed system implements the feedforward control-based pulse-density-modulation control scheme with pulsewidth-modulation feedback control strategy to compensate temperature and other environmental influences on ozone gas output.

Current-source type parallel inductor-compensated load resonant inverter with PDM control scheme for efficient ozonizer

This paper is concerned with a study on the high-frequency current source-fed type parallel inductor-compensated load-resonant inverter for an ozonizer, together with some output regulation characteristics. In addition, an effective power control method for a current-source inverter type ozonizer is introduced. This inverter can operate under the principle of the PDM (pulse density modulation) and PWM hybrid power regulation strategy. It is noted that this inverter makes the control system simple, thus leading to improve the ozone generation efficiency.

DSP-based PDM and PWM type voltage-fed load-resonant inverter with high-voltage transformer for silent discharge ozonizer

This paper presents a high-frequency voltage source-fed load-resonant IGBT inverter with a series-compensated resonant inductor for ozonizer, which incorporates the power control strategy on the basis of pulse density modulation (PDM). This PDM inverter operation is illustrated through the circuit modeling of the silent discharge-based ozone generating tube as well as high-voltage transformer. The state-of-the art ozonizer using a voltage-fed type high-frequency load resonant inverter is demonstrated, and its operating principle is described for driving the ozone generating tube. It is noted that the pulse density modulated series resonant high-frequency inverter using IGBTs makes an ozone generating system simple, which is able to improve the ozone generation efficiency. Finally, it is proved that the series load resonant inverter type ozonizer developed in this paper provides stable silent discharge characteristics over a wide output power range from 10% to 100%.

Pulse density modulated high-frequency load resonant inverter for ozonizer and its feasible performance evaluations

In this paper, the voltage source series compensated inductor type capacitive load-resonant high-frequency inverter with a high-voltage matching transformer link is presented for driving a silent discharge ozone generating tube load used as a newly-developed ozonizer. The optimum design value of the series compensated resonant inductor for the capacitive load of an ozone generating tube is indicated. The effective power regulation scheme of this ozonizer using a voltage-fed resonant inverter is proposed, which is based on a PDM (pulse density modulation) related PWM strategy due to DSP implementation. The effectiveness of this ozonizer is proved in experiment as well as the simulation results.

A sinusoidal pulse width modulated inverter using three-winding high-frequency flyback transformer for PV power conditioner

This paper presents a novel prototype of the utility-interfacing sinusoidal pulse width modulation (SPWM) inverter using the high-frequency flyback transformer for the small-scale solar photovoltaic power conditioner (1 kW - 4 kW). The proposed SPWM power conditioner circuit with a high-frequency link has a function of electrical isolation, which is vital for PV power conditioner systems with the viewpoint of safety, noise requirement and convenience. The discontinuous conduction mode (DCM) operation of the flyback transformer link pulse modulation is also introduced to establish a simple topology of the inverter circuit and control scheme. The proposed PV power conditioner operates with ZVS when it turns off the primary-side switches by the high-frequency switching. This reduces the power losses of the semi-conductor device switchings and improves the power conversion efficiency of the total system as PV power processor. The operating principle of the proposed circuit is described for the understanding of the circuit parameters establishment. Then, the digital control scheme is demonstrated herein. The proposed power conditioner is verified on the basis of the computer simulations and experiments. The experimented results show the validity of the proposed power conditioner to have high power conversion efficiency and low harmonic distortions.

Series-compensated inductor type resonant inverter using pulse density modulation scheme for efficient ozonizer

This paper presents a high-frequency voltage source-fed load-resonant IGBT inverter with a series-compensated resonant inductor for ozonizer power supply, which is characterized by the power control strategy on the basis of pulse density modulation (PDM). The inverter system configuration illustrated through the circuit modeling of the silent discharge-based ozone generating tube and high-voltage transformer. The state-of-the art ozonizer using a high-frequency load resonant inverter is demonstrated and its operating principle of the voltage-fed load-resonant inverter are described for the ozone generating tube. It is noted that the pulse density modulated series resonant high-frequency inverter using IGBTs makes an ozonizer power control scheme simple as well as improves the ozone generating characteristic. Thus, it is effective in improving the ozone producer efficiency. Finally, it is proved that the series load-resonant inverter type ozonizer developed in this paper provides stable silent discharge characteristics over a wide output power range from 10% to 100%.

Novel current control scheme with deadbeat algorithm and adaptive line enhancer for three-phase current-source active power filter

For an active power filter (APF), a three-phase current source PWM converter using IGBTs is not always used in place of a three-phase voltage source PWM converter with a voltage regulated DC capacitor. This is due to the difficulty of current control implementation for three-phase current source PWM converter. In this paper, the effective method to apply three-phase current-source PWM converter with a deadbeat controller to APF is presented. In this APF, the compensation of current harmonics is attained by setting the control purpose compensating the instantaneous reactive current component in load current and reducing the ripple in the instantaneous actual current component. In three-phase current source PWM converter, the time-optimal response for utility AC grid side input current is two-dimensional finite time settling response, in which two sampling periods are required for a settling time. To cancel this delay and one more delay caused by DSP control strategy, the reference value of three sampling periods ahead has to be predicted. For this prediction, the adaptive filter is introduced. Finally, it is proven from an experimental point of view that the compensating ability of this APF is very accurate though the PWM frequency is rather low.

Lossless capacitive snubber assisted auxiliary resonant DC link voltage source soft switching inverter

This paper presents a voltage source-type soft switching space voltage vector modulated inverter using the latest IGBTs which incorporates two soft commutation techniques; the first one is the utilization of the active auxiliary resonant DC link snubber circuit and the second one is that, in some cases soft switching can be achieved using only the lossless snubber capacitor (LLSC) independently. The soft commutation operating principle of the proposed LLSC-assisted ARDCL is discussed. In addition, the effectiveness of this improved soft switching scheme is proved on the basis of simulation data and experimental results.

High frequency PWM boost chopper-fed DC-DC converters with coupled-inductors

In this paper, an advanced two quadrant PWM chopper type DC-DC converter with high boost voltage ratio using coupled inductors and low switch peak voltage stress is proposed for new type parallel processing UPS applications in addition to new energy interface systems. Moreover, a soft switching boost chopper-fed DC-DC converter with high step-up voltage conversion ratio is also proposed. These two boost chopper circuit topologies are evaluated and compared on the basis of simulation and experimental results.

Three phase soft switching inverter with pulse current transformer-assisted resonant snubbers

In this paper, a high frequency pulse current transformer-assisted auxiliary active resonant commutation snubber (HFTA-ARCS) for voltage source power conversion is proposed. A three phase voltage source type soft switching inverter incorporating HFTA-ARCS circuits in its three bridge legs can reduce the current rating of the auxiliary active power switches and simplified sensorless control scheme without the specified boost current management required for soft switching. Its operating principle and digital control scheme are described and a practical design method of circuit parameters on this HFTA-ARCS circuit is also introduced on the basis of computer simulation results. Moreover, this space vector modulated soft switching inverter system with DSP-based digital control scheme is discussed on the basis of performance evaluations. The effectiveness of this inverter is proved by simulation results and this inverter system is also compared with the conventional three-phase hard switching inverter under the conditions of specified parameters.