Geun Hie Rim

Novel zero-voltage and zero-current-switching (ZVZCS) full bridge PWM converter using a simple auxiliary circuit

A novel zero voltage and zero current switching (ZVZCS) full bridge (FB) PWM power converter is presented to simplify the circuits of the previously presented ZVSCS power converters. A simple auxiliary circuit which consists of one small capacitor and two small diodes is added in the secondary to provide ZVZCS conditions to primary switches as well as to clamp secondary rectifier voltage. The additional clamp circuit for the secondary rectifier is not necessary. The auxiliary circuit includes neither lossy components nor additional active switches which makes the proposed power converter efficient and cost effective. The principle of operation, features and design considerations are illustrated and verified on a 2.5 kW, 100 kHz IGBT-based experimental circuit.

Solid state Marx Generator using series-connected IGBTs

Pulsed power supplies using solid state switches have been widely studied recently. Use of high power semiconductors such as IGBTs and IGCTs have become an area of interest today. To make this, several type of pulse generators using solid state devices have been adopted and tested in many papers. In this paper, a boost converter array using series-connected switches is presented. The electrical circuit is made of a boost converter array to produce high voltage pulses. To verify the proposed converter, an experimental equipment with a 20 kV, 300 A pulse generator was made and food treatment results are shown.

Development and Optimization of High-Voltage Power Supply System for Industrial Magnetron

This paper describes the design and analysis of a 42-kW (14 kV, 3 A) high-voltage power supply for a 30-kW industrial magnetron drive. The design is based on a series resonant converter in discontinuous conduction mode (DCM) to take advantage of both the superior arc protection stemming from the current source characteristics and the high power density owing to the use of parasitic elements such as the leakage inductance in the high-voltage transformer. The detailed design procedure for the resonant tank and high-voltage transformer with respect to the input and output specifications is described on the basis of a simplified analysis of the DCM series resonant converter. Special considerations for designing high-power high-voltage power supplies are provided, such as series stacking of diodes for a voltage doubling rectifier and insulation between each winding of the high-voltage transformer. In addition, a comparative study using theoretical equations, simulation, and experimental results was carried out. This study yielded the output voltage and current characteristics at different switching frequencies and verified the advantages of this topology, such as arc protection without an additional protection circuit and high efficiency due to zero-current or zero-voltage switching. Moreover, the parallel operation of two converters with phase shifted gating signal is proposed to reduce the output current ripple and increase power capability for higher power magnetron drive. Additionally, the design considerations of two auxiliary power supplies (a filament power supply: 15 V, 150 A and a magnet power supply: 50 V, 5 A) are also provided and optimized for effective driving industrial magnetron. Finally, the developed power supply was tested with a 30-kW industrial magnetron, and the results prove the reliability and robustness of the proposed scheme.

Comparative Study of MOSFET and IGBT for High Repetitive Pulsed Power Modulators

This paper presents an investigation of semiconductor switches for high voltage solid-state pulsed power modulators from the viewpoint of pulse rising time, efficiency, and reliability. A comparative study of insulated gate bipolar transistor (IGBT) and metal oxide semiconductor field effect transistor (MOSFET) devices is provided, focusing particularly on the characteristics of each device for pulsed power applications. Two kinds of stacks for 10-kV pulses are developed with a high voltage capacitor charger in order to experimentally compare the characteristics of each device. Although the structure of each stack is similar, the number of power cells for the 10-kV pulse is different due to the device voltage rating. The power cell voltage for IGBT and MOSFET-based stacks is about 840 V and 560 V, respectively. Therefore, two types of transformer, with six secondary windings for the IGBT stack and nine secondary windings for the MOSFET stack, are also designed for storage capacitor charging. Moreover, the ease of varying the pulse repetition rate and the pulse width shows the advantages of the developed modulators in facilitating the measurement of device characteristics in different pulse output conditions. The experiments are performed with noninductive resistor loads, and the results of the comparison tests are discussed. In addition, the results prove that the developed modulator can be effectively used for high repetitive pulsed power applications.

Development of 60kV Pulse Power Generator Based on IGBT Stacks for Wide Application

In this paper, a novel new pulse power generator based on IGBT stacks is proposed for pulse power application. The proposed scheme consists of series connected 9 power stages to generate maximum 60 kV output pulse and one series resonant power inverter to charge DC capacitor voltage. Each power stage is configured as 8 series connected power cells and each power cell generates up to 850 V DC pulse. Finally pulse output voltage is applied using a total of 72 series connected IGBTs. The synchronization of gating signal is important for series operation of IGBTs. For gating signal synchronization, a full bridge inverter and a pulse transformer generates on-off signals of IGBT gating and specially designed gate power circuit was used. The proposed scheme has lots of advantages such as long lifecyle, compact size, flat topped pulse forming, small weight, protection for arc, high efficiency, and flexibility to generate various kinds of pulse output. The operation of proposed pulse power supply was tested for PSII application and is confirmed that the proposed scheme can effectively be used for wide pulse power applications

Novel zero voltage transition PWM converter for switched reluctance motor drives

A novel zero-voltage-transition (ZVT) PWM converter for switched reluctance motor (SRM) drives is proposed. A simple auxiliary circuit which consists of one active switch, one resonant inductor, and three diodes provides ZVS condition to all main switches and diodes allowing high frequency operation of the converter with high efficiency. The auxiliary circuit is placed in parallel with the main power flow path and thus it handles only a small fraction of the main power. So, the power rating of the auxiliary circuit can be very small (about 30% of main power). So, the auxiliary circuit can be realized with small power rating and low cost. Operation, features and characteristics of the proposed converter are illustrated and verified on a 1.5 kW, 50 kHz IGBT based (a MOSFET for the auxiliary switch) experimental circuit.

Analysis of the Pulsed Plasma Reactor Impedance For DeSOx and DeNOx

The impedance characteristics of the wire-plate pulsed plasma reactor for deSOx and deNOx were investigated by experiment. The impedance characteristics of the reactor were mainly varied with charge voltage, wire length and wire-plate distance. In addition, we performed an analysis of the nonlinear reactor impedance on the basis of experiment and EMTP work.

Status of KERI's Pulsed Power Research and Development

This paper reviews the research and development results achieved in the Korea Electrotechnology Research Institute (KERI) in a decade. KERI develops pulsed power technology and its applications are mostly based on power electronics. KERIs research and development activity covers components, military systems, and industry applications. High-voltage switching means developed in KERI are a rotary arc gap (RAG) switch (11 kV and 400 kAp), a vacuum RAG (20 kV and 150 kAp), an inverse pinch switch (20 kV and 150 kAp), and 10-kV semiconductor switch stacks made of thyristors and Insulated Gate Bipolar Transistors (IGBTs). The IGBT and thyristor stacks consist of 10 or 12 1.2-kV discrete devices and are operated by only one active drive circuit installed in the groundside. Some ferromagnetic opening switch schemes are also researched on trial bases. Some of KERIs research and development works from devices to application systems will be described.

A compact pulse generator using diode opening switch for engine gas treatment application

In this paper a compact pulse generator is proposed for NOx removal system using a corona discharge effect from the exhaust gas of engine cars. A compact pulser based on diodes for opening switches and inductive energy storage has been developed. The pulser consists of a pulse compression circuit including a primary low-voltage stored capacitor, a semiconductor closing switch (a thyristor) as its initial switch, a saturable pulse transformer, and secondary high-voltage circuit including a capacitor, opening diodes, and a resistive load. The experiment results of a proposed pulser with resistance of 200 Omega are following: the voltage amplitude is about 21 kV, the rise time (between 0.1~0.9 of amplitude) is about 21 ns, the pulse width in full width at half maximum (FWHM) is about 42 ns

A 120-kV, 5-kA Multipurpose Pulsed-Power Generator Using a Semiconductor Switch and Magnetic Pulse Compression

This paper describes a high-frequency pulsed-power generator for various industrial applications such as water treatment, food and medical apparatus for sterilization, or polluted gas treatment. The system is made of silicon-controlled rectifier as a main trigger switch, capacitors, two-stage magnetic pulse compression stages, and a linear transformer to generate a maximum of 120-kV, 5-kA pulse. The parameters obtained through the development are: output voltage: 120 kV (maximum), pulse repetition ration: 300 pulse per second, pulsewidth: