1999 IEEE Africon. 5th Africon Conference in Africa (Cat. No.99CH36342)
Coupling effieieneies for several metals at room temperature 16 3.2 Dimensions of the gold work-p... more Coupling effieieneies for several metals at room temperature 16 3.2 Dimensions of the gold work-piece to be melted in the induction furnace 4.1 Resonant frequencies for various metals at room temperature The first aim of this research is therefore to provide the South African jewellery industry with a low cost induction furnace capable of melting and alloying small quantities of precious metal such as gold, silver and platinum. The second aim of this research is to provide a laboratory standard induction furnace capable of electrically heating any metal for experimental purposes. Thi, application frequency. The metal which is to be heated (work-p' xe), is situated inside a refractory crucible, which is placed inside the heating coil. When the coil is loaded a resulting shift in the resonant freqUency of the tank circuit occurs. This shi ft in resonant frequency is directly related to the loading effect, which depends on the resistivity of the work-piece and the efficiency of coupling between the work-piece and the coil!!. This shift is compensated for by manually adjusting the driving frequency of the power source to the new load resonant frequency. During a heating cycle, an IIlcrease in work-piece temperature causes an increase work-piece resistivity, whieh in turn also causes a shiti in the resonant irequenev of the tank circuit. When melting metals by induction, it is predicted that a further shin In
Previously, HySA Systems reported about integration of an MH extension tank in electric forklift ... more Previously, HySA Systems reported about integration of an MH extension tank in electric forklift with commercial (Plug Power Inc.) fuel cell power module [1-3]. This prototype is in operation at Impala Platinum refineries in Springs, South Africa, since September 2015. Here, we present 15 kWe fuel cell power module (as a replacement for the commercial one) which was developed and integrated by HySA Systems. The power module is built around commercial liquid cooled proton exchange membrane fuel cell (PEM FC) from Ballard. The fuel cell stack and DC to DC converter cooling loops are coupled with the integrated metal hydride hydrogen storage system in order to utilize released heat for hydrogen desorption. The fuel cell stack is electrically connected with seven 12V Pb-acid batteries connected in series, to achieve 84 V bus voltage. The fuel cell approach temperature (61 °C) is precisely controlled by means of two passive mixing valves and by variable controlled fan speed. The air afte...
IEEE International Symposium on Industrial Electronics. Proceedings. ISIE'98 (Cat. No.98TH8357)
Abstract - An induction furnace using a current-source, full-bridge load-resonant MOSFET inverter... more Abstract - An induction furnace using a current-source, full-bridge load-resonant MOSFET inverter suitable for melting small amounts of precious metal (gold and platinum) is presented. Melting times of 25 seconds were achieved at a power level of approximately 900 watts. A ...
ISIE'2000. Proceedings of the 2000 IEEE International Symposium on Industrial Electronics (Cat. No.00TH8543)
A miniature high frequency induction furnace has been developed for the melting and alloying of s... more A miniature high frequency induction furnace has been developed for the melting and alloying of small quantities (50g) of metal for laboratory and jewellery applications. The induction heating load forms part of a resonant circuit whose frequency is determined by the electrical characteristics of the work-piece placed inside the heating coil. The dynamic nature of the induction-heating load is such
2005 International Conference on Power Electronics and Drives Systems
Page 1. IEEE PEDS 2005 Optimised Control for High Frequency Induction Heating Power Sources Irsha... more Page 1. IEEE PEDS 2005 Optimised Control for High Frequency Induction Heating Power Sources Irshad Khan Edson Naylor Jon Tapson Department ofElectrical Engineering Department ofElectrical Engineering Department ofElectrical Engineering ...
Publisher Summary This chapter discusses the basic concepts, circuits, and technologies for gate ... more Publisher Summary This chapter discusses the basic concepts, circuits, and technologies for gate drives in power converters, mainly focusing on voltage-controlled devices like power MOSFETs and IGBTs. Global trends towards energy efficiency over the last three decades have facilitated the need for technological advancements in the design and control of power electronic converters for energy processing. Voltage-controlled devices are semiconductors which require a constant voltage drive on the gate control terminal in order to remain in conduction. The input drive requirements of these devices are substantially lower than their current-driven counterparts and are the preferred choice in modern power electronics. Two such devices are the power MOSFET and the IGBT which are forced commutated switching devices being fully controlled at the gate terminal under normal operating conditions. Both MOSFETs and IGBTs require sufficient charge deposited into their gate junctions, whilst maintaining a minimum gate threshold voltage in order to remain in conduction. When designing a gate driver, it is always important to understand both the static and dynamic behavior of the semiconductor devices used as it aids the effectiveness of the design for a given gate driver system.
El pasado día 27 de julio de 2001 se celebró en Tegucigalpa (Honduras) la conferencia regional 3 ... more El pasado día 27 de julio de 2001 se celebró en Tegucigalpa (Honduras) la conferencia regional 3 sobre la integración y el desarrollo de Centroamérica en el siglo XXI que celebraba el 40 aniversario de la constitución del Banco Centroamericano de Integración Económica (BCIE). El acto fue inaugurado con las palabras del Presidente del BCIE, Pablo Schneider. 1 Esta crónica debió aparecer en el número anterior de la Revista, habíendose quedado fuera por un error de composición del mismo. A ella se hacía alusión precisamente en la primera nota a pie de página del artículo de Gert ROSENTHAl, p. 461. 2 Profesor de ETEA. 3 El término regional en América latina tiene una acepción diferente a la común en el entorno europeo. En todo el texto se debe entender región como grupo de países de América Latina que participan en algún tipo de acuerdo de integración.
The frequency of these induced Eddy currents in the work-piece is determined by the frequency of ... more The frequency of these induced Eddy currents in the work-piece is determined by the frequency of 'hc power source. These eddy currents are induced into a peripheral layer of the work-piece known as the skin-depth (0) or penetration depth which is characteristic of current tlow at high frequency due to skin effect is given by: . !P
1999 IEEE Africon. 5th Africon Conference in Africa (Cat. No.99CH36342)
Coupling effieieneies for several metals at room temperature 16 3.2 Dimensions of the gold work-p... more Coupling effieieneies for several metals at room temperature 16 3.2 Dimensions of the gold work-piece to be melted in the induction furnace 4.1 Resonant frequencies for various metals at room temperature The first aim of this research is therefore to provide the South African jewellery industry with a low cost induction furnace capable of melting and alloying small quantities of precious metal such as gold, silver and platinum. The second aim of this research is to provide a laboratory standard induction furnace capable of electrically heating any metal for experimental purposes. Thi, application frequency. The metal which is to be heated (work-p' xe), is situated inside a refractory crucible, which is placed inside the heating coil. When the coil is loaded a resulting shift in the resonant freqUency of the tank circuit occurs. This shi ft in resonant frequency is directly related to the loading effect, which depends on the resistivity of the work-piece and the efficiency of coupling between the work-piece and the coil!!. This shift is compensated for by manually adjusting the driving frequency of the power source to the new load resonant frequency. During a heating cycle, an IIlcrease in work-piece temperature causes an increase work-piece resistivity, whieh in turn also causes a shiti in the resonant irequenev of the tank circuit. When melting metals by induction, it is predicted that a further shin In
Previously, HySA Systems reported about integration of an MH extension tank in electric forklift ... more Previously, HySA Systems reported about integration of an MH extension tank in electric forklift with commercial (Plug Power Inc.) fuel cell power module [1-3]. This prototype is in operation at Impala Platinum refineries in Springs, South Africa, since September 2015. Here, we present 15 kWe fuel cell power module (as a replacement for the commercial one) which was developed and integrated by HySA Systems. The power module is built around commercial liquid cooled proton exchange membrane fuel cell (PEM FC) from Ballard. The fuel cell stack and DC to DC converter cooling loops are coupled with the integrated metal hydride hydrogen storage system in order to utilize released heat for hydrogen desorption. The fuel cell stack is electrically connected with seven 12V Pb-acid batteries connected in series, to achieve 84 V bus voltage. The fuel cell approach temperature (61 °C) is precisely controlled by means of two passive mixing valves and by variable controlled fan speed. The air afte...
IEEE International Symposium on Industrial Electronics. Proceedings. ISIE'98 (Cat. No.98TH8357)
Abstract - An induction furnace using a current-source, full-bridge load-resonant MOSFET inverter... more Abstract - An induction furnace using a current-source, full-bridge load-resonant MOSFET inverter suitable for melting small amounts of precious metal (gold and platinum) is presented. Melting times of 25 seconds were achieved at a power level of approximately 900 watts. A ...
ISIE'2000. Proceedings of the 2000 IEEE International Symposium on Industrial Electronics (Cat. No.00TH8543)
A miniature high frequency induction furnace has been developed for the melting and alloying of s... more A miniature high frequency induction furnace has been developed for the melting and alloying of small quantities (50g) of metal for laboratory and jewellery applications. The induction heating load forms part of a resonant circuit whose frequency is determined by the electrical characteristics of the work-piece placed inside the heating coil. The dynamic nature of the induction-heating load is such
2005 International Conference on Power Electronics and Drives Systems
Page 1. IEEE PEDS 2005 Optimised Control for High Frequency Induction Heating Power Sources Irsha... more Page 1. IEEE PEDS 2005 Optimised Control for High Frequency Induction Heating Power Sources Irshad Khan Edson Naylor Jon Tapson Department ofElectrical Engineering Department ofElectrical Engineering Department ofElectrical Engineering ...
Publisher Summary This chapter discusses the basic concepts, circuits, and technologies for gate ... more Publisher Summary This chapter discusses the basic concepts, circuits, and technologies for gate drives in power converters, mainly focusing on voltage-controlled devices like power MOSFETs and IGBTs. Global trends towards energy efficiency over the last three decades have facilitated the need for technological advancements in the design and control of power electronic converters for energy processing. Voltage-controlled devices are semiconductors which require a constant voltage drive on the gate control terminal in order to remain in conduction. The input drive requirements of these devices are substantially lower than their current-driven counterparts and are the preferred choice in modern power electronics. Two such devices are the power MOSFET and the IGBT which are forced commutated switching devices being fully controlled at the gate terminal under normal operating conditions. Both MOSFETs and IGBTs require sufficient charge deposited into their gate junctions, whilst maintaining a minimum gate threshold voltage in order to remain in conduction. When designing a gate driver, it is always important to understand both the static and dynamic behavior of the semiconductor devices used as it aids the effectiveness of the design for a given gate driver system.
El pasado día 27 de julio de 2001 se celebró en Tegucigalpa (Honduras) la conferencia regional 3 ... more El pasado día 27 de julio de 2001 se celebró en Tegucigalpa (Honduras) la conferencia regional 3 sobre la integración y el desarrollo de Centroamérica en el siglo XXI que celebraba el 40 aniversario de la constitución del Banco Centroamericano de Integración Económica (BCIE). El acto fue inaugurado con las palabras del Presidente del BCIE, Pablo Schneider. 1 Esta crónica debió aparecer en el número anterior de la Revista, habíendose quedado fuera por un error de composición del mismo. A ella se hacía alusión precisamente en la primera nota a pie de página del artículo de Gert ROSENTHAl, p. 461. 2 Profesor de ETEA. 3 El término regional en América latina tiene una acepción diferente a la común en el entorno europeo. En todo el texto se debe entender región como grupo de países de América Latina que participan en algún tipo de acuerdo de integración.
The frequency of these induced Eddy currents in the work-piece is determined by the frequency of ... more The frequency of these induced Eddy currents in the work-piece is determined by the frequency of 'hc power source. These eddy currents are induced into a peripheral layer of the work-piece known as the skin-depth (0) or penetration depth which is characteristic of current tlow at high frequency due to skin effect is given by: . !P
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