EPE Association: EPE 2009 - Subtopic 19-2: 'Industry Specific Energy Conversion and Conditioning Technologies'

EPE 2009 - Subtopic 19-2: 'Industry Specific Energy Conversion and Conditioning Technologies'
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2009 - Conference > EPE 2009 - Topic 19: 'Industry Specific Energy Conversion and Conditioning Technologies' > EPE 2009 - Subtopic 19-2: 'Industry Specific Energy Conversion and Conditioning Technologies'

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   18 PULSE CONTROLLED RECTIFIER: A CASE STUDY ON UPS
By Ibrahim SEFA, Necmi ALTIN, Ilhami COLAK, Saban OZDEMIR [View]
[Download]

Abstract: Controlled/uncontrolled rectifiers draw harmonic reach currents from the grid. Harmonic components of the line current affect the grid and other equipment around the point of common coupling. Therefore, so the grid current harmonic distortion levels must be kept at desired level. Multi-pulse rectifiers are commonly used in high power rectifier systems to reduce grid current harmonics and improve power factor. In this study, design, simulation and application of a 18 pulse controlled rectifier for constant DC output under varying load conditions has been introduced. The proposed system consists of 0.218 kVA rated differential star connected phase shifting autotransformer to reduce the size and cost of the system. Experimental results of 6 and 12 pulse controlled rectifier are also given for comparison reasons. Simulation and experimental results show that the grid current harmonics are reduced and kept below the acceptable levels, and the power factor is also improved by using 18 pulse controlled rectifier.

   A Converter Topology for High Speed Motor Drive Applications
By virginie GUENNEGUES, Bernard GOLLENTZ, Farid MEIBODY-TABAR, StÃ©phane RAEL, LoÃ¯c LECLERE [View]
[Download]

Abstract: In the area of natural gas industry, there is a large interest in converters for driving high speed, medium voltage induction motors. High-speed drive systems are capable of directly driving turbocompressors at speeds of up to 20,000 rpm / 8MW. In high speed motor drive applications, the motor fundamental frequency can vary from 100Hz to 300Hz, which requires a high switching frequency. However, switching losses increase with switching frequency and these losses represent a critical point for high voltage semiconductors. Soft switching topology could represent a relevant solution to work at high switching frequency. The drawback of such a converter is the number of added components and the complexity of the control. Multilevel inverters provide output signals with low harmonic distortion. When the number of level increases, the output voltage THD decreases but the size and the cost of the system increases as well. The switching voltage is reduced when the number of level increases, depending on the topologies, or when a series connection of components is made. This paper reports a 3-level converter structure for high speed motor drive applications that allows decreasing switching losses in comparison with the well known 3-level NPC (Neutral Point Clamped) inverter [1]. This feature leads to the possibility to increase the switching frequency or the load current level thanks to series connection of IGBTs. As the neutral point is actively piloted, this structure is named NPP (Neutral Point Piloted).

   A NOVEL SPEED CONTROLLER FOR SINGLE/TWO-PHASE FRACTIONAL HORSE-POWER MOTORS.
By Jesus Sergio ARTAL, Antonio USON, JesÃºs LETOSA, Miguel SAMPLON [View]
[Download]

Abstract: The widespread use of small induction motors for home appliances and other applications justify the development of new drives and motor designs. The aim shall be to save energy and to consume it with a clean absorption of current from the mains. The basis of the system proposed in this paper is to generate sinusoidal waveforms using digital techniques (they are stored in an EEPROM as reference vectors). These waveforms are composed to obtain a 2-phase voltage system, with variable amplitude and frequency, to feed small electric power drives. The two parameters of the waveforms -amplitude and frequency- in the motor are easily regulated and amplified by means of semiconductors working in PWM mode. This new drive provides advantages as a straightforward control method, simplicity of the design, easily regulated starting torque and its low cost. As a whole, the design leads to a robust, compact, cheap unit, easy to manufacture.

   A peak power limitation method for multi-drive systems
By Sjoerd BOSGA [View]
[Download]

Abstract: In industrial installations with several drives, total peak power will often be equal to the sum of all individual peak powers. This article demonstrates that through proper interaction between drives, peak power can be very much limited, sometimes by a factor two. This is done by controlling the power of one or more drives connected to high-inertia loads as a function of the power required for control of highly dynamic loads. The feasibility is demonstrated on a hybrid servo press installation, where an existing flywheel is used as a buffer for a newly installed servo drive. Practical implementation issues are discussed and measurements from a prototype installation are presented.

   Analog Fixed Maximum Power Point Control for a PWM Step-down Converter for Water Pumping Installations
By Hector BELTRAN SAN SEGUNDO, Emilio PEREZ, Zhe CHEN, Francisco Javier GIMENO-SALES, Salvador SEGUI-CHILET, Josep SOLER, Emilio DAROQUI [View]
[Download]

Abstract: This paper describes a Fixed Maximum Power Point analog control used in a step-down Pulse Width Modulated power converter. The DC/DC converter drives a DC motor used in small water pumping installations, without any electric storage device. The power supply is provided by PV panels working around their maximum power point, with a fixed operating voltage value. The control circuit implementation is not only simple and cheap, but also robust and reliable. System protections and adjustments are also proposed. Simulations and hardware are reported in the paper for a 150W water pumping application system. The proposed Optimal Power Point fix voltage control system is analyzed in comparison to other complex controls.

   Analyses of Power Consumption and Losses in Relation to Supply Voltage Quality
By Toomas VINNAL [View]
[Download]

Abstract: This paper is focused on active and reactive power consumption and power losses in the consumer power system depending upon supply voltage quality. Supply voltage level deviations from rated voltage affect directly power consumption and power losses in the consumer power system. Active and reactive power relation to supply voltage is characterized by load factors. In the paper a practical method for determining the load factors of active and reactive power in relation to supply voltage is described. Also harmonic distortions of supply voltage and current affect power losses and need more attention in the consumer power systems.

   Characterization of a New PLC Modem for an Industrial Application
By Marc Anthony MANNAH, Christophe BATARD, Nicolas GINOT, Mohamed MACHMOUM [View]
[Download]

Abstract: The motor speed control is a typical industrial application where an extra cable is used in order to transmit control informationâ€™s from the motor to the controller. This cable is used for data transmission such as rotor speed, rotor position, temperature and vibrations. One cable is used per motor. In some cases, it might have length exceeding few hundred meters, which can be problematic in terms of price and overall dimension. The aim of our study is to develop an industrial power line communication (PLC) modem allowing transmission through the feeder cable based on the PLC technology without using extra cabling. PLC technology exists already in the market but its reliability has only been demonstrated in domestic application through the electrical network 230V/50Hz. The power signal through the feeder cable is the Pulse Width modulation (PWM) signal which is a signal of higher frequency and higher amplitude than in domestic network and it can affect badly on communication. According to this, this paper will underline the reason of non communication of the PLC technology in this situation and the way to overcome it. We will define many characteristics of the PLC modem that will allow us to couple the information to the three phase cable and to communicate safely in order to ensure the controllability of the motor.

   Concentric Induction Heating for Dismantlable Adhesion Method
By KAZUHISA KIKUCHI [View]
[Download]

Abstract: A dismantlable (=dismantle-able) adhesion method using electromagnetic induction heating (IH) and thermoplastic adhesive has been proposed. The feature of this method is easily able to bond and dismantle in many times. In conventional interior works, a circle type induction coil is applied. But this coil is ineffective for concentric heating and deep distance heating to load metal. So due to effective adhesion depend on induction heating (IH), we carry an experiment on the new concentric coil with ferrite core because it generates many magnetic fluxes to load metal at deep distance. In the study, a single-phase concentric coil using U-shape ferrite core is proposed. Its experiments and analysis for induction heating (IH) and the electric characteristics are discussed in this paper, and the usefulness of proposed coil is proved.

   Design of a PWM Current Source Rectifier for High Power Induction Melting Applications
By Sebastian RICHTER, Philipp GAERTNER, Dirk HIRSCHMANN, Rik DE DONCKER [View]
[Download]

Abstract: PWM current source converters (CSCs) can directly replace traditional thyristor rectifiers in many industrial applications to improve power quality significantly. In this work, a design process for PWM current source rectifiers in the range of 1 â€“ 10MVA is developed. Different PWM techniques for CSCs are reviewed in the light of semiconductor losses and harmonic distortion of the modulated current. A design procedure for the ac-filter (LC-filter) is proposed that identifies filter designs that comply to emission limits for harmonic currents as well as thermal limits of the semiconductors. The design procedure is verified by detailed simulations. Results of a real-world case study are presented.

   Development of a Magnetic Field Generator at 20 kHz using a Voltage-Source Inverter for Biological Research
By Shintaro KOGURE, Keiji WADA, Yukihisa SUZUKI [View]
[Download]

Abstract: This paper presents an alternating magnetic-field generator at 20 kHz for biological research using a single phase inverter and a series LC resonant circuit. Both single coil and multiple coil magnetic-field generators are designed and their effectiveness is confirmed by analytical and experimental results. These results demonstrate that the magnetic-field generator can produce 8 mT at a frequency of 20 kHz at the midpoint of the single-coil with low distortion of magnetic flux waveform. Additionally, the multiple-coil magnetic-field generator produces the distribution of uniform magnetic flux over a larger volume than the single-coil magnetic-field generator.

   Evaluation of control strategies for load balancing of a tensioning device with individually driven S-rolls
By Philippe SAEY, Jeroen DE POORTER, John GIJS, Geert DECONINCK, Philippe LATAIRE [View]
[Download]

Abstract: Skin-pass 3 of ArcelorMittal Gent has 2 tensioning devices with 5 S-rolls each that are driven with a common planetary gear system. The DC-drive and the planetary gear system will be replaced by induction machines for each individual S-roll during the future renovation. In this paper, different control strategies for load balancing are evaluated.

   High efficient inductive energy- and data transmission system with special coil geometry
By Christian RATHGE [View]
[Download]

Abstract: This paper presents a combined contactless energy and data transmission system, which is able to detect and to identify a secondary device and which is also able to check its absolute position during the energy transfer. Such an identification is needed in many fields of application under aspects like safety and security. Compared to conventional industrial communication systems like Bluetooth or W-LAN using the near field technique allows the elimination of interferences between systems which operate at the same transmission frequency and furthermore which operate in a very near range side by side. This reduces the complexity, the costs and the installation effort of the overall system and makes a transport protocol for the data transfer completely unnecessary. In this paper a combined inductive energy and data transmission system is proposed which allows a power transmission of 1 kW over an air gap of 30 mm as well as an inductive data transmission on the principle of inductive near field coupling at the same time. By using a special coil geometry for the data transmission, a nearly full separation between the inductive energy and data transmission channels is reached. For dimensioning the coil parameters the 3D-FEA and analytic calculations of the electrical behaviour are used. The interferences between the energy and data transmission system are modelled and simulated with a multi coupled transformer model. The paper shows important aspects of the optimisation process of the data coils and also presents an optimal coil configuration in PCB layout. Finally the simulation and the measurement results are discussed in the paper.

   Indoor Power Harvesting Using Photovoltaic Cells for Low Power Applications
By Adel NASIRI [View]
[Download]

Abstract: Utilization of low power indoor devices such as remote sensors, supervisory and alarm systems, distributed controls, and data transfer system are on steady rise. Due to remote and distributed nature of these systems, it is attractive to avoid using electrical wiring to supply power to them. Primary batteries have been used for this application for many years but they require regular maintenance at usually hard to access places. This paper provides a complete analysis of a PV harvesting system for indoor low power applications. The characteristics of a target load, photovoltaic (PV) cell and power conditioning circuit are discussed. Different choices of energy storage are also explained. Implementation and test results of the system are presented that highlights the practical issues and limitations of the system.

   Stabilization of the DC-link of Voltage Fed Inverters
By VICENTE ESTEVE, Jose JORDAN, enrique DEDE, enrique MASET , esteban SANCHIS KILDERS, juan b. EJEA, agustin FERRERES, cesar CASES, magraner JOSE MIGUEL, raul HERR [View]
[Download]

Abstract: This paper analyses the behaviour of the DC-link of a high power (50 kW), high frequency (150 kHz) voltage fed inverter with a series resonant load circuit for industrial induction heating applications which is characterized by a full bridge inverter with a power control based on pulse density modulation (PDM). The operation of this power control strategy can cause large oscillations of the voltage at the input of the inverter due to its discontinuous operation and the inductances and the capacitances of the circuit. A design method based on simulation results is presented. The results are verified experimentally using a prototype for induction hardening applications

   Superheated Steam Generator by Indcution Heating
By Hideo TOMITA [View]
[Download]

Abstract: Induction heating is an effective method for metal heating. One of the unique applications of induction heating, there is a superheated steam generator. We propose a novel superheated steamer having both advantages for cooling of induction coil and for warming of water in advance. In the paper, the structure and behavior of proposed steamer driven by high frequency inverter are described, and its usefulness is proved.

   Voltage Swell/Sag Compensation with Single-Phase Z-Source AC/AC Converter
By Minh-Khai NGUYEN, Young-Gook JUNG, Young-Cheol LIM [View]
[Download]

Abstract: This paper proposes a new type of voltage swell/sag compensator based on single-phase Z-source AC/AC converter. The proposed topology employs a pulse width modulation (PWM) Z-source AC/AC converter along with a transformer. A commutation strategy to drive the AC/AC converter is employed to realize snubberless operation. Circuit analysis is provided. Simulation and experimental results at 20\% voltage swell, 40\% voltage swell and 60\% voltage sag are shown.

EPE 2009 - Subtopic 19-2: 'Industry Specific Energy Conversion and Conditioning Technologies'
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2009 - Conference > EPE 2009 - Topic 19: 'Industry Specific Energy Conversion and Conditioning Technologies' > EPE 2009 - Subtopic 19-2: 'Industry Specific Energy Conversion and Conditioning Technologies'
	[return to parent folder]

	18 PULSE CONTROLLED RECTIFIER: A CASE STUDY ON UPS By Ibrahim SEFA, Necmi ALTIN, Ilhami COLAK, Saban OZDEMIR	[View] [Download]
Abstract: Controlled/uncontrolled rectifiers draw harmonic reach currents from the grid. Harmonic components of the line current affect the grid and other equipment around the point of common coupling. Therefore, so the grid current harmonic distortion levels must be kept at desired level. Multi-pulse rectifiers are commonly used in high power rectifier systems to reduce grid current harmonics and improve power factor. In this study, design, simulation and application of a 18 pulse controlled rectifier for constant DC output under varying load conditions has been introduced. The proposed system consists of 0.218 kVA rated differential star connected phase shifting autotransformer to reduce the size and cost of the system. Experimental results of 6 and 12 pulse controlled rectifier are also given for comparison reasons. Simulation and experimental results show that the grid current harmonics are reduced and kept below the acceptable levels, and the power factor is also improved by using 18 pulse controlled rectifier.

	A Converter Topology for High Speed Motor Drive Applications By virginie GUENNEGUES, Bernard GOLLENTZ, Farid MEIBODY-TABAR, StÃ©phane RAEL, LoÃ¯c LECLERE	[View] [Download]
Abstract: In the area of natural gas industry, there is a large interest in converters for driving high speed, medium voltage induction motors. High-speed drive systems are capable of directly driving turbocompressors at speeds of up to 20,000 rpm / 8MW. In high speed motor drive applications, the motor fundamental frequency can vary from 100Hz to 300Hz, which requires a high switching frequency. However, switching losses increase with switching frequency and these losses represent a critical point for high voltage semiconductors. Soft switching topology could represent a relevant solution to work at high switching frequency. The drawback of such a converter is the number of added components and the complexity of the control. Multilevel inverters provide output signals with low harmonic distortion. When the number of level increases, the output voltage THD decreases but the size and the cost of the system increases as well. The switching voltage is reduced when the number of level increases, depending on the topologies, or when a series connection of components is made. This paper reports a 3-level converter structure for high speed motor drive applications that allows decreasing switching losses in comparison with the well known 3-level NPC (Neutral Point Clamped) inverter [1]. This feature leads to the possibility to increase the switching frequency or the load current level thanks to series connection of IGBTs. As the neutral point is actively piloted, this structure is named NPP (Neutral Point Piloted).

	A NOVEL SPEED CONTROLLER FOR SINGLE/TWO-PHASE FRACTIONAL HORSE-POWER MOTORS. By Jesus Sergio ARTAL, Antonio USON, JesÃºs LETOSA, Miguel SAMPLON	[View] [Download]
Abstract: The widespread use of small induction motors for home appliances and other applications justify the development of new drives and motor designs. The aim shall be to save energy and to consume it with a clean absorption of current from the mains. The basis of the system proposed in this paper is to generate sinusoidal waveforms using digital techniques (they are stored in an EEPROM as reference vectors). These waveforms are composed to obtain a 2-phase voltage system, with variable amplitude and frequency, to feed small electric power drives. The two parameters of the waveforms -amplitude and frequency- in the motor are easily regulated and amplified by means of semiconductors working in PWM mode. This new drive provides advantages as a straightforward control method, simplicity of the design, easily regulated starting torque and its low cost. As a whole, the design leads to a robust, compact, cheap unit, easy to manufacture.

	A peak power limitation method for multi-drive systems By Sjoerd BOSGA	[View] [Download]
Abstract: In industrial installations with several drives, total peak power will often be equal to the sum of all individual peak powers. This article demonstrates that through proper interaction between drives, peak power can be very much limited, sometimes by a factor two. This is done by controlling the power of one or more drives connected to high-inertia loads as a function of the power required for control of highly dynamic loads. The feasibility is demonstrated on a hybrid servo press installation, where an existing flywheel is used as a buffer for a newly installed servo drive. Practical implementation issues are discussed and measurements from a prototype installation are presented.

	Analog Fixed Maximum Power Point Control for a PWM Step-down Converter for Water Pumping Installations By Hector BELTRAN SAN SEGUNDO, Emilio PEREZ, Zhe CHEN, Francisco Javier GIMENO-SALES, Salvador SEGUI-CHILET, Josep SOLER, Emilio DAROQUI	[View] [Download]
Abstract: This paper describes a Fixed Maximum Power Point analog control used in a step-down Pulse Width Modulated power converter. The DC/DC converter drives a DC motor used in small water pumping installations, without any electric storage device. The power supply is provided by PV panels working around their maximum power point, with a fixed operating voltage value. The control circuit implementation is not only simple and cheap, but also robust and reliable. System protections and adjustments are also proposed. Simulations and hardware are reported in the paper for a 150W water pumping application system. The proposed Optimal Power Point fix voltage control system is analyzed in comparison to other complex controls.

	Analyses of Power Consumption and Losses in Relation to Supply Voltage Quality By Toomas VINNAL	[View] [Download]
Abstract: This paper is focused on active and reactive power consumption and power losses in the consumer power system depending upon supply voltage quality. Supply voltage level deviations from rated voltage affect directly power consumption and power losses in the consumer power system. Active and reactive power relation to supply voltage is characterized by load factors. In the paper a practical method for determining the load factors of active and reactive power in relation to supply voltage is described. Also harmonic distortions of supply voltage and current affect power losses and need more attention in the consumer power systems.

	Characterization of a New PLC Modem for an Industrial Application By Marc Anthony MANNAH, Christophe BATARD, Nicolas GINOT, Mohamed MACHMOUM	[View] [Download]
Abstract: The motor speed control is a typical industrial application where an extra cable is used in order to transmit control informationâ€™s from the motor to the controller. This cable is used for data transmission such as rotor speed, rotor position, temperature and vibrations. One cable is used per motor. In some cases, it might have length exceeding few hundred meters, which can be problematic in terms of price and overall dimension. The aim of our study is to develop an industrial power line communication (PLC) modem allowing transmission through the feeder cable based on the PLC technology without using extra cabling. PLC technology exists already in the market but its reliability has only been demonstrated in domestic application through the electrical network 230V/50Hz. The power signal through the feeder cable is the Pulse Width modulation (PWM) signal which is a signal of higher frequency and higher amplitude than in domestic network and it can affect badly on communication. According to this, this paper will underline the reason of non communication of the PLC technology in this situation and the way to overcome it. We will define many characteristics of the PLC modem that will allow us to couple the information to the three phase cable and to communicate safely in order to ensure the controllability of the motor.

	Concentric Induction Heating for Dismantlable Adhesion Method By KAZUHISA KIKUCHI	[View] [Download]
Abstract: A dismantlable (=dismantle-able) adhesion method using electromagnetic induction heating (IH) and thermoplastic adhesive has been proposed. The feature of this method is easily able to bond and dismantle in many times. In conventional interior works, a circle type induction coil is applied. But this coil is ineffective for concentric heating and deep distance heating to load metal. So due to effective adhesion depend on induction heating (IH), we carry an experiment on the new concentric coil with ferrite core because it generates many magnetic fluxes to load metal at deep distance. In the study, a single-phase concentric coil using U-shape ferrite core is proposed. Its experiments and analysis for induction heating (IH) and the electric characteristics are discussed in this paper, and the usefulness of proposed coil is proved.

	Design of a PWM Current Source Rectifier for High Power Induction Melting Applications By Sebastian RICHTER, Philipp GAERTNER, Dirk HIRSCHMANN, Rik DE DONCKER	[View] [Download]
Abstract: PWM current source converters (CSCs) can directly replace traditional thyristor rectifiers in many industrial applications to improve power quality significantly. In this work, a design process for PWM current source rectifiers in the range of 1 â€“ 10MVA is developed. Different PWM techniques for CSCs are reviewed in the light of semiconductor losses and harmonic distortion of the modulated current. A design procedure for the ac-filter (LC-filter) is proposed that identifies filter designs that comply to emission limits for harmonic currents as well as thermal limits of the semiconductors. The design procedure is verified by detailed simulations. Results of a real-world case study are presented.

	Development of a Magnetic Field Generator at 20 kHz using a Voltage-Source Inverter for Biological Research By Shintaro KOGURE, Keiji WADA, Yukihisa SUZUKI	[View] [Download]
Abstract: This paper presents an alternating magnetic-field generator at 20 kHz for biological research using a single phase inverter and a series LC resonant circuit. Both single coil and multiple coil magnetic-field generators are designed and their effectiveness is confirmed by analytical and experimental results. These results demonstrate that the magnetic-field generator can produce 8 mT at a frequency of 20 kHz at the midpoint of the single-coil with low distortion of magnetic flux waveform. Additionally, the multiple-coil magnetic-field generator produces the distribution of uniform magnetic flux over a larger volume than the single-coil magnetic-field generator.

	Evaluation of control strategies for load balancing of a tensioning device with individually driven S-rolls By Philippe SAEY, Jeroen DE POORTER, John GIJS, Geert DECONINCK, Philippe LATAIRE	[View] [Download]
Abstract: Skin-pass 3 of ArcelorMittal Gent has 2 tensioning devices with 5 S-rolls each that are driven with a common planetary gear system. The DC-drive and the planetary gear system will be replaced by induction machines for each individual S-roll during the future renovation. In this paper, different control strategies for load balancing are evaluated.

	High efficient inductive energy- and data transmission system with special coil geometry By Christian RATHGE	[View] [Download]
Abstract: This paper presents a combined contactless energy and data transmission system, which is able to detect and to identify a secondary device and which is also able to check its absolute position during the energy transfer. Such an identification is needed in many fields of application under aspects like safety and security. Compared to conventional industrial communication systems like Bluetooth or W-LAN using the near field technique allows the elimination of interferences between systems which operate at the same transmission frequency and furthermore which operate in a very near range side by side. This reduces the complexity, the costs and the installation effort of the overall system and makes a transport protocol for the data transfer completely unnecessary. In this paper a combined inductive energy and data transmission system is proposed which allows a power transmission of 1 kW over an air gap of 30 mm as well as an inductive data transmission on the principle of inductive near field coupling at the same time. By using a special coil geometry for the data transmission, a nearly full separation between the inductive energy and data transmission channels is reached. For dimensioning the coil parameters the 3D-FEA and analytic calculations of the electrical behaviour are used. The interferences between the energy and data transmission system are modelled and simulated with a multi coupled transformer model. The paper shows important aspects of the optimisation process of the data coils and also presents an optimal coil configuration in PCB layout. Finally the simulation and the measurement results are discussed in the paper.

	Indoor Power Harvesting Using Photovoltaic Cells for Low Power Applications By Adel NASIRI	[View] [Download]
Abstract: Utilization of low power indoor devices such as remote sensors, supervisory and alarm systems, distributed controls, and data transfer system are on steady rise. Due to remote and distributed nature of these systems, it is attractive to avoid using electrical wiring to supply power to them. Primary batteries have been used for this application for many years but they require regular maintenance at usually hard to access places. This paper provides a complete analysis of a PV harvesting system for indoor low power applications. The characteristics of a target load, photovoltaic (PV) cell and power conditioning circuit are discussed. Different choices of energy storage are also explained. Implementation and test results of the system are presented that highlights the practical issues and limitations of the system.

	Stabilization of the DC-link of Voltage Fed Inverters By VICENTE ESTEVE, Jose JORDAN, enrique DEDE, enrique MASET , esteban SANCHIS KILDERS, juan b. EJEA, agustin FERRERES, cesar CASES, magraner JOSE MIGUEL, raul HERR	[View] [Download]
Abstract: This paper analyses the behaviour of the DC-link of a high power (50 kW), high frequency (150 kHz) voltage fed inverter with a series resonant load circuit for industrial induction heating applications which is characterized by a full bridge inverter with a power control based on pulse density modulation (PDM). The operation of this power control strategy can cause large oscillations of the voltage at the input of the inverter due to its discontinuous operation and the inductances and the capacitances of the circuit. A design method based on simulation results is presented. The results are verified experimentally using a prototype for induction hardening applications

	Superheated Steam Generator by Indcution Heating By Hideo TOMITA	[View] [Download]
Abstract: Induction heating is an effective method for metal heating. One of the unique applications of induction heating, there is a superheated steam generator. We propose a novel superheated steamer having both advantages for cooling of induction coil and for warming of water in advance. In the paper, the structure and behavior of proposed steamer driven by high frequency inverter are described, and its usefulness is proved.

	Voltage Swell/Sag Compensation with Single-Phase Z-Source AC/AC Converter By Minh-Khai NGUYEN, Young-Gook JUNG, Young-Cheol LIM	[View] [Download]
Abstract: This paper proposes a new type of voltage swell/sag compensator based on single-phase Z-source AC/AC converter. The proposed topology employs a pulse width modulation (PWM) Z-source AC/AC converter along with a transformer. A commutation strategy to drive the AC/AC converter is employed to realize snubberless operation. Circuit analysis is provided. Simulation and experimental results at 20\% voltage swell, 40\% voltage swell and 60\% voltage sag are shown.