This paper provides an analysis about early incipient failures in three-phase induction motor bea... more This paper provides an analysis about early incipient failures in three-phase induction motor bearings when driven by PWM inverters, focusing on a real industrial case. The preliminarily defined potential problems were firstly discussed on a theoretical basis and afterwards being experimentally assessed by means of vibration, stator current and common mode current data acquisition and analysis. Following the investigation, it was concluded that the presence of common mode currents at the verified levels could cause damages to the motor bearings. This result could be confirmed when the machine stopped working due to another failure of the bearings.
2017 13th International Conference and Expo on Emerging Technologies for a Smarter World (CEWIT), 2017
In apartments, houses and hotels, showers are by far the biggest consumers of water, responding t... more In apartments, houses and hotels, showers are by far the biggest consumers of water, responding to about 25% of the total volume consumed every month. When winter hits big cities and temperatures fall, the hot water consumption increases dramatically. Since end users often dispense cold water present in the pipelines until the heated water from the reservoirs is perceived in showers or other points of use, hotels and residential buildings are responsible for a considerable waste of treated water. Several solutions based on local hardware have been proposed to partially overcome this problem, but many of them try to reduce the waste of water at the expense of reducing the efficiency of the heating and recirculating systems. The age of the IoT has brought to the smart buildings new perspectives regarding to rational use of resources, providing savings and real comfort for users. This work proposes a smart water heating scheme, mediated by IoT technology, for large buildings in urban settings. The main goal is ensuring the minimal waste of water as well as energy economy in pumping and heating systems. The proposed automated solution is built from an open-source Asterisk-based IP-PBX on cloud computing technology. A complete experimental setup considering a residential building in the southeastern region of Brazil is implemented and tested. The achieved benefits are tangible and significant when compared to the dedicated existing systems.
2019 IEEE Applied Power Electronics Conference and Exposition (APEC), 2019
In high power applications, medium voltage (MV) power converters have proven to be the best solut... more In high power applications, medium voltage (MV) power converters have proven to be the best solution for dealing with large amounts of energy, reducing power losses and decreasing costs. The importance of such equipment has placed its service continuity as the most relevant concern for researchers and engineers. In this work an IoT scheme is proposed to remotely manage the remaining useful life of IGBT power modules based on their failure precursors. The proposed structure was designed to permit remote and automatic actuation in the power converter according to the degradation levels of its power devices.
2018 IEEE Industry Applications Society Annual Meeting (IAS), 2018
Power Electronics applications for Metal Industry deal with high voltage and currents. The heat d... more Power Electronics applications for Metal Industry deal with high voltage and currents. The heat dissipation of the power losses of the static switches should be the most appropriate in terms of reliability, power density, and cost. This paper discusses an oil immersion heat dissipation application. An explanation of the thermal circuit for static switches and most used cooling methods are presented. A case study aiming to design an immersion tank for heat dissipation is demonstrated. Experimental results of air and oil dissipation are presented and compared.
Mine hoist systems play a vital role in gold ore transportation. They are the connection between ... more Mine hoist systems play a vital role in gold ore transportation. They are the connection between the underground mine and the beneficiation plant. As a result, any hoist system interruption compromises the production. In this paper, it is proposed a mission critical analysis and design methodology for power converters in order to achieve proper reliability of the hoist drive system. Since the failure of power devices is responsible for a significant portion of the total downtime of power converters, a detailed study of the insulated gate bipolar transistor (IGBT) power modules lifetime is carried out. The three level neutral-point-clamped and Active Neutral Point Clamped (ANPC) IGBT-based topologies are considered for this application. The recently presented Fault-Tolerant (FT)-ANPC converter is proposed as a higher reliability solution leading to longer power modules and drive system lifetimes. All the studies are based on practical operating data from a 900-m deep shaft hoist system operating in a gold mine in southeastern Brazil.
IECON 2014 - 40th Annual Conference of the IEEE Industrial Electronics Society, 2014
The bulk materials transportation from the mines to their destination is an important activity th... more The bulk materials transportation from the mines to their destination is an important activity that often represents the major part of the total mining costs. More and more frequently, high-capacity belt conveyors in mining are efficiently driven employing medium-voltage power converters connected with large induction motors. Unfortunately, medium-voltage power converters use a high number of power semiconductors which are ranked as the most fragile components of a drive system and the failure of any of these devices often causes a total collapse of the converter, resulting in the conveyor system downtime with large financial losses for companies. In this work the authors will present new design alternatives for the most used power converter technologies aiming its fault-tolerant and fault-resilient operation. As the total tolerance to any kind of failure is still a practical impossibility, in the cases where catastrophic failures cause the converter breakdown and the conveyor downtime, it will be shown how to limit the damage pattern in the equipment, minimizing the maintenance costs and time-to-repair.
2014 IEEE Applied Power Electronics Conference and Exposition - APEC 2014, 2014
ABSTRACT The integrated gate commutated thyristor (IGCT) and the press-pack power diodes are succ... more ABSTRACT The integrated gate commutated thyristor (IGCT) and the press-pack power diodes are successfully applied in medium-voltage Neutral Point Clamped (NPC) converters in the power range from hundreds of kW to tenth of MW. Responsible for driving key processes in various industries, the requirements of reliability and high availability of these converters are absolutely relevant, since its repair or replacement may take too much time. Given the vital importance of such equipment for the electric drive systems, they are equipped with protection schemes which are usually reliable but not infallible. If the protection scheme of the converter does not work properly in a fault situation, serious damages may be expected in the power semiconductor devices. These catastrophic effects can be alleviated by a fault-resilient design of the converter's bus bars, limiting the damage pattern in the converter to their least complex parts. In this work the thermal behavior of the power semiconductors is investigated using finite element models in the COMSOL Multiphysics software. Simulations and experimental measurements are made to attest the effectiveness of the fault-resilient design.
Belt conveyors constitute an efficient and economical way for minerals and heavy-load transportat... more Belt conveyors constitute an efficient and economical way for minerals and heavy-load transportation from mines to their destination, serving vital process units whose success depends on continuous operation. To meet important operational requirements, modern high-capacity conveyor systems are equipped with medium-voltage variable-speed induction motor drives. The reliability and service continuity of such drives play a critical role in the entire conveyor availability. This paper proposes an alternative to significantly improve the availability of the conveyor systems by using fault-resilient medium-voltage ac drives. Based on recent studies and the authors' experience, it is shown in this paper how the conveyor drive downtime can be dramatically reduced after an internal short circuit, keeping the overall cost to repair to a minimum and avoiding financial losses that can reach several million dollars.
In the metal industry, rolling is the most widely used steel forming process to provide high prod... more In the metal industry, rolling is the most widely used steel forming process to provide high production and control of final product. Rolling mills must be able to change the speed of the strip at the same time that the speed is controlled within precise limits. Furthermore, this application has a severe load profile, with high torque variations during the lamination process. These characteristics include rolling mills among the classical mission critical industry applications (MCIA). In addition to the high cost/failure rate, rolling mills have a critical dynamic loading, making the design of a reliable system doubly challenging. Design for reliability (DFR) is the process conducted during the design of a component or system that ensures them to perform at the required reliability level. In the context of the power converters for rolling mills and other MCIA, the DFR should be known and adopted in the design of the converter proper (component level) well as in the specification of power converters (system level). This paper contributes to the knowledge in the field by proposing a methodology covering the necessary steps for decision making during the design (component level) and selection (systems level) of power converters for MCIA. A rolling mill system from a large steel plant in southeastern Brazil is adopted as the case study. The standard high power converter solution is compared with two high reliability converter topologies: the fault-tolerant active neutral point clamped and the triple-star bridge cells modular multilevel converter. The importance of DFR in mission critical applications is demonstrated.
This paper presents a strategy for protecting high power IGCT-based converters which are currentl... more This paper presents a strategy for protecting high power IGCT-based converters which are currently used in a wide range of drive applications. The protection of such converters against internal faults has been addressed in the technical literature, but the main focus has been on the solutions to disconnect the converter from the mains. In this paper, the short circuit current paths through the power devices are identified and studied from the perspective of keeping the overall repair cost after a fault to a minimum. It is shown that a preferred short-circuit current path that limits the thermal energy in all IGCTs to safe levels exists. Furthermore, it is demonstrated that it is possible to guarantee, through proper busbar geometry and/or device selection, that the short-circuit current stress can always be moved to the power diodes. Simulation results are presented to support all the discussions and conclusions, avoiding the costs and risks of tests on a medium voltage prototype.
High-frequency problems involving long cable PWM motor drive systems are well documented in the l... more High-frequency problems involving long cable PWM motor drive systems are well documented in the literature. Solutions based on passive filters are conventionally used to suppress these undesired phenomena that take place in such systems, but, in turn, bring up new considerations concerning filter size, weight, cost, and electrical losses. In this context, a concept of an alternative motor drive system
This paper provides an analysis about early incipient failures in three-phase induction motor bea... more This paper provides an analysis about early incipient failures in three-phase induction motor bearings when driven by PWM inverters, focusing on a real industrial case. The preliminarily defined potential problems were firstly discussed on a theoretical basis and afterwards being experimentally assessed by means of vibration, stator current and common mode current data acquisition and analysis. Following the investigation, it was concluded that the presence of common mode currents at the verified levels could cause damages to the motor bearings. This result could be confirmed when the machine stopped working due to another failure of the bearings.
2017 13th International Conference and Expo on Emerging Technologies for a Smarter World (CEWIT), 2017
In apartments, houses and hotels, showers are by far the biggest consumers of water, responding t... more In apartments, houses and hotels, showers are by far the biggest consumers of water, responding to about 25% of the total volume consumed every month. When winter hits big cities and temperatures fall, the hot water consumption increases dramatically. Since end users often dispense cold water present in the pipelines until the heated water from the reservoirs is perceived in showers or other points of use, hotels and residential buildings are responsible for a considerable waste of treated water. Several solutions based on local hardware have been proposed to partially overcome this problem, but many of them try to reduce the waste of water at the expense of reducing the efficiency of the heating and recirculating systems. The age of the IoT has brought to the smart buildings new perspectives regarding to rational use of resources, providing savings and real comfort for users. This work proposes a smart water heating scheme, mediated by IoT technology, for large buildings in urban settings. The main goal is ensuring the minimal waste of water as well as energy economy in pumping and heating systems. The proposed automated solution is built from an open-source Asterisk-based IP-PBX on cloud computing technology. A complete experimental setup considering a residential building in the southeastern region of Brazil is implemented and tested. The achieved benefits are tangible and significant when compared to the dedicated existing systems.
2019 IEEE Applied Power Electronics Conference and Exposition (APEC), 2019
In high power applications, medium voltage (MV) power converters have proven to be the best solut... more In high power applications, medium voltage (MV) power converters have proven to be the best solution for dealing with large amounts of energy, reducing power losses and decreasing costs. The importance of such equipment has placed its service continuity as the most relevant concern for researchers and engineers. In this work an IoT scheme is proposed to remotely manage the remaining useful life of IGBT power modules based on their failure precursors. The proposed structure was designed to permit remote and automatic actuation in the power converter according to the degradation levels of its power devices.
2018 IEEE Industry Applications Society Annual Meeting (IAS), 2018
Power Electronics applications for Metal Industry deal with high voltage and currents. The heat d... more Power Electronics applications for Metal Industry deal with high voltage and currents. The heat dissipation of the power losses of the static switches should be the most appropriate in terms of reliability, power density, and cost. This paper discusses an oil immersion heat dissipation application. An explanation of the thermal circuit for static switches and most used cooling methods are presented. A case study aiming to design an immersion tank for heat dissipation is demonstrated. Experimental results of air and oil dissipation are presented and compared.
Mine hoist systems play a vital role in gold ore transportation. They are the connection between ... more Mine hoist systems play a vital role in gold ore transportation. They are the connection between the underground mine and the beneficiation plant. As a result, any hoist system interruption compromises the production. In this paper, it is proposed a mission critical analysis and design methodology for power converters in order to achieve proper reliability of the hoist drive system. Since the failure of power devices is responsible for a significant portion of the total downtime of power converters, a detailed study of the insulated gate bipolar transistor (IGBT) power modules lifetime is carried out. The three level neutral-point-clamped and Active Neutral Point Clamped (ANPC) IGBT-based topologies are considered for this application. The recently presented Fault-Tolerant (FT)-ANPC converter is proposed as a higher reliability solution leading to longer power modules and drive system lifetimes. All the studies are based on practical operating data from a 900-m deep shaft hoist system operating in a gold mine in southeastern Brazil.
IECON 2014 - 40th Annual Conference of the IEEE Industrial Electronics Society, 2014
The bulk materials transportation from the mines to their destination is an important activity th... more The bulk materials transportation from the mines to their destination is an important activity that often represents the major part of the total mining costs. More and more frequently, high-capacity belt conveyors in mining are efficiently driven employing medium-voltage power converters connected with large induction motors. Unfortunately, medium-voltage power converters use a high number of power semiconductors which are ranked as the most fragile components of a drive system and the failure of any of these devices often causes a total collapse of the converter, resulting in the conveyor system downtime with large financial losses for companies. In this work the authors will present new design alternatives for the most used power converter technologies aiming its fault-tolerant and fault-resilient operation. As the total tolerance to any kind of failure is still a practical impossibility, in the cases where catastrophic failures cause the converter breakdown and the conveyor downtime, it will be shown how to limit the damage pattern in the equipment, minimizing the maintenance costs and time-to-repair.
2014 IEEE Applied Power Electronics Conference and Exposition - APEC 2014, 2014
ABSTRACT The integrated gate commutated thyristor (IGCT) and the press-pack power diodes are succ... more ABSTRACT The integrated gate commutated thyristor (IGCT) and the press-pack power diodes are successfully applied in medium-voltage Neutral Point Clamped (NPC) converters in the power range from hundreds of kW to tenth of MW. Responsible for driving key processes in various industries, the requirements of reliability and high availability of these converters are absolutely relevant, since its repair or replacement may take too much time. Given the vital importance of such equipment for the electric drive systems, they are equipped with protection schemes which are usually reliable but not infallible. If the protection scheme of the converter does not work properly in a fault situation, serious damages may be expected in the power semiconductor devices. These catastrophic effects can be alleviated by a fault-resilient design of the converter's bus bars, limiting the damage pattern in the converter to their least complex parts. In this work the thermal behavior of the power semiconductors is investigated using finite element models in the COMSOL Multiphysics software. Simulations and experimental measurements are made to attest the effectiveness of the fault-resilient design.
Belt conveyors constitute an efficient and economical way for minerals and heavy-load transportat... more Belt conveyors constitute an efficient and economical way for minerals and heavy-load transportation from mines to their destination, serving vital process units whose success depends on continuous operation. To meet important operational requirements, modern high-capacity conveyor systems are equipped with medium-voltage variable-speed induction motor drives. The reliability and service continuity of such drives play a critical role in the entire conveyor availability. This paper proposes an alternative to significantly improve the availability of the conveyor systems by using fault-resilient medium-voltage ac drives. Based on recent studies and the authors' experience, it is shown in this paper how the conveyor drive downtime can be dramatically reduced after an internal short circuit, keeping the overall cost to repair to a minimum and avoiding financial losses that can reach several million dollars.
In the metal industry, rolling is the most widely used steel forming process to provide high prod... more In the metal industry, rolling is the most widely used steel forming process to provide high production and control of final product. Rolling mills must be able to change the speed of the strip at the same time that the speed is controlled within precise limits. Furthermore, this application has a severe load profile, with high torque variations during the lamination process. These characteristics include rolling mills among the classical mission critical industry applications (MCIA). In addition to the high cost/failure rate, rolling mills have a critical dynamic loading, making the design of a reliable system doubly challenging. Design for reliability (DFR) is the process conducted during the design of a component or system that ensures them to perform at the required reliability level. In the context of the power converters for rolling mills and other MCIA, the DFR should be known and adopted in the design of the converter proper (component level) well as in the specification of power converters (system level). This paper contributes to the knowledge in the field by proposing a methodology covering the necessary steps for decision making during the design (component level) and selection (systems level) of power converters for MCIA. A rolling mill system from a large steel plant in southeastern Brazil is adopted as the case study. The standard high power converter solution is compared with two high reliability converter topologies: the fault-tolerant active neutral point clamped and the triple-star bridge cells modular multilevel converter. The importance of DFR in mission critical applications is demonstrated.
This paper presents a strategy for protecting high power IGCT-based converters which are currentl... more This paper presents a strategy for protecting high power IGCT-based converters which are currently used in a wide range of drive applications. The protection of such converters against internal faults has been addressed in the technical literature, but the main focus has been on the solutions to disconnect the converter from the mains. In this paper, the short circuit current paths through the power devices are identified and studied from the perspective of keeping the overall repair cost after a fault to a minimum. It is shown that a preferred short-circuit current path that limits the thermal energy in all IGCTs to safe levels exists. Furthermore, it is demonstrated that it is possible to guarantee, through proper busbar geometry and/or device selection, that the short-circuit current stress can always be moved to the power diodes. Simulation results are presented to support all the discussions and conclusions, avoiding the costs and risks of tests on a medium voltage prototype.
High-frequency problems involving long cable PWM motor drive systems are well documented in the l... more High-frequency problems involving long cable PWM motor drive systems are well documented in the literature. Solutions based on passive filters are conventionally used to suppress these undesired phenomena that take place in such systems, but, in turn, bring up new considerations concerning filter size, weight, cost, and electrical losses. In this context, a concept of an alternative motor drive system
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