Publication: Estrategias avanzadas de control, modelado, diseño e implementación de controladores de potencia de estado sólido (SSPC) para su aplicación en sistemas de distribución de potencia eléctrica embarcados
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2010-12
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2011-02-28
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Actualmente, existe una fuerte tendencia en los nuevos diseños de aviones militares y civiles hacia el concepto de avión más eléctrico ó totalmente eléctrico. Esto es debido principalmente a la substitución de los sistemas mecánicos, neumáticos e hidráulicos por sistemas parcial o totalmente eléctricos. El concepto de avión más eléctrico presenta una serie de ventajas o mejoras frente a los aviones convencionales, desde el punto de vista de eficiencia, peso, volumen, impacto ambiental, etc. En estos aviones los tradicionales sistemas de distribución de potencia eléctrica (SDPE) son un elemento clave debido, principalmente, a los nuevos requisitos de demanda de potencia y las funcionalidades requeridas. Esto ha provocado que los nuevos sistemas eléctricos hayan evolucionado hacia nuevas arquitecturas de distribución, basadas en sistemas distribuidos, donde los tradicionales niveles de tensión 28 VCC y 115 VCA, han sido sustituidos por niveles de 270 VCC, ±270 VCC y 230 VCA. Los nuevos SDPE han originado que los aviones más eléctricos requirieran de un mayor número de equipos electrónicos, como son convertidores CC/CC, rectificadores, inversores y protecciones de estado sólido, que permiten hacer frente a las necesidades planteadas en estas nuevas arquitecturas. Un elemento clave de estos nuevos SDPE es la introducción de los controladores de potencia de estado sólido (SSPC) como elementos de protección del cableado y de control de las cargas eléctricas. Estos dispositivos permiten la sustitución de los magneto-térmicos y relés que se usan en los convencionales SDPE, los cuales presentan problemas de funcionamiento en los nuevos SDPE debido, principalmente, a los cambios en los niveles de tensión. Además, el desarrollo de la funcionalidad y nuevas capacidades de los SSPC está ligado a la configuración de las nuevas arquitecturas de los sistemas eléctricos, a los elementos con los que interaccionan, su localización dentro de la arquitectura y las cargas a las que se conectan. Dentro de estos sistemas, la conexión de determinadas cargas, como las altamente capacitivas, implica la necesidad de desarrollar nuevas estrategias de control orientados a mejorar el proceso de conexión de este tipo de cargas. En este trabajo de investigación, se ha realizado un análisis detallado de cinco procedimientos de conexión de cargas altamente capacitivas, mediante circuitos de control constituidos con elementos pasivos y activos. De este modo, se han presentado nuevos procedimientos de control activo de la corriente por el SSPC, aplicables durante la conexión, que permiten conectar cargas altamente capacitivas. Las estrategias de control activo, desarrolladas en esta tesis doctoral, que permiten la conexión de cargas muy capacitivas son: control activo por corriente constante, control activo por derivada de corriente constante, control activo generalizado y control activo por trayectoria óptima de la corriente. En cada uno de los métodos de conexión de cargas altamente capacitivas, se han definido ecuaciones sencillas que permiten calcular el condensador máximo que es posible cargar en función del tiempo de la conexión, la corriente nominal, la corriente máxima y el valor de la parte resistiva de la carga. Por otro lado, teniendo en cuenta el incremento de la complejidad de los nuevos SDPE embarcados, los modelos de los SSPC juegan un papel fundamental a la hora de reproducir el funcionamiento de estos componentes y anticipar posibles problemas de funcionamiento dentro de las nuevas arquitecturas. No obstante, los fabricantes de SSPC no proporcionan modelos de estos dispositivos. Por lo tanto, con el fin de analizar los efectos de estos nuevos dispositivos de protección en los sistemas embarcados, se hace necesario desarrollar nuevos modelos de SSPC, que permitan, en un primer lugar, predecir fallos de funcionamiento y, en segundo lugar, detectar los efectos introducidos por los SSPC en los sistemas una vez integrados junto al resto del componentes, simplificando el proceso de validación de la funcionalidad de todo el sistema. Por estas razones, otro de los objetivos planteados en esta tesis es el desarrollo de modelos que permitan validar el comportamiento de los SSPC, durante las diferentes fases del proceso de desarrollo y posterior integración dentro del SDPE. Así pues, en esta tesis se presentan dos tipos de modelos aplicables a los SSPC. El primero se denomina modelo estructural, y está basado en la estructura del componente. Este tipo de modelo es específico para cada fabricante de SSPC y tiene que ser modificado de acuerdo con la estructura interna de cada uno de los SSPC. El modelo permite detectar problemas durante las fases de diseño, previo al montaje final del dispositivo. En este modelo estructural se incluyen algoritmos, que permiten calcular los tiempos de activación de distintos tipos de protecciones (I2t, sobrecorriente, cortocircuito, etc.). El segundo modelo propuesto en la tesis es el basado en el modelado comportamental del SSPC. Este modelo se fundamenta en bloques, que son totalmente independientes de la estructura interna del SSPC. Esto permite configurarlo de acuerdo con las hojas de características proporcionadas por el fabricante y las medidas experimentales del dispositivo comercial. Otra de las ventajas de este modelo es la sencillez con la que se puede exportar a distintas plataformas de simulación. Los modelos comportamentales propuestos han sido validados con SSPC comerciales. Finalmente, en esta tesis se han desarrollado dos prototipos de SSPC. El prototipo final ha permitido validar experimentalmente las diferentes estrategias de control para la conexión de cargas altamente capacitivas mediante el uso del SSPC con tecnología MOSFET. Además, se han validado diferentes funcionalidades del SSPC, como puede ser la protección i2t, la protección contra cortocircuito, el efecto de la memoria térmica, y la disipación de la temperatura, etc. Por otra parte, se ha validado el modelo estructural y el modelo comportamental, a partir de las medidas experimentales sobre el prototipo construido. Por último, se han validado el funcionamiento del prototipo de SSPC con tecnología IGBT. -------------------------------------------------------------------------------------------------------------------------------------------------------------------
There is a strong trend in the new designs of military and civil aircraft towards the concept of more or fully electric aircraft. This is mainly due to the replacement of pneumatic and hydraulic systems by fully or partially electrical systems. The concept of more electric aircraft presents a series of advantages and improvements in comparison with conventional aircraft, from the point of view of efficiency, weight, volume, environmental impact, etc. In these new aircrafts the electrical power distribution systems (PDS) are the key element, principally due to the new requirements of demanded power and the required functionality. Therefore the new electrical systems have evolved towards new distribution architectures based on distributed systems, where traditional voltages levels at 28 VDC and 115 VAC, have been replaced by levels of 270 VDC, ±270 VDC and 230 VAC. Because of these new PDS, more electric aircrafts require a greater number of electronic equipments, such as converters, rectifiers, inverters and solid state protections, that allow to fulfil the needs arising from these new architectures. One of the key elements of these new PDS is the introduction of the solid state power controllers (SSPC) as elements of wiring protection and control of the electrical loads. These devices allow to replace the magneto-thermal and relays that are used in the conventional SDP, since these conventional devices present operational problems in the new PDS, due mainly to the changes in the voltage levels. Furthermore, the development of the new functionality and capabilities of the SSPC are related to: the configuration of the new PDS architectures, the elements that interact, their location within the architecture and the loads to which they connect. Within these systems, the connection of certain loads, such as the highly capacitive loads, imply the need to develop new control strategies to improve the process the connection of such loads. In this research, a detailed analysis of five procedures for connecting highly capacitive loads has been done. The five procedures are implemented with control circuits made with passive and active elements. Therefore, new methods have been presented in order to obtain the active control of the current through the SSPC, applicable during connection period, which allow the connection of highly capacitive loads. The active control methods developed within this thesis are the following: active control with constant current, active control with slope constant current, generalized active control and active control by optimum trajectory current. Each method has been defined by simple equations that allow to calculate the maximum capacitor that is possible to be charged during the connection, as a function of the nominal current, the maximum current and the value of the resistive component part of the load. Taking into the account the complexity of the new onboard PDS, the SSPC models play a fundamental role when the function of the components is being reproduced to anticipate potential problems of operating within the new architectures. However, SSPC manufacturers do not provide models of these devices. In order to analyze the effects of these new devices of the onboard systems, it is necessary to develop new models of SSPC, which allow, on one hand, predicting malfunctions and, on the other hand, detecting the effects inducted by the SSPC in PDS when integrated with the rest of the components. Thus, these models allow simplifying the process of validating the functionality of the whole system. Therefore, one of the goals outlined in the thesis has been the development of the models that allow to validate the behaviour of SSPC during the different stages of the development process and their further integration in the PDS. In this thesis two types of models have been presented, that are applicable to the SSPC. The first type is a structural model, and it is based on the internal structure of the SSPC. This model allows to detect problems during the design phases, before final assembly of the device. The second model, which has been proposed in the thesis, is based on the SSPC behavioural modelling. This model is divided in blocks, which are entirely independent of the of the SSPC internal structure. Therefore, it can be configured according to the datasheets provided by the manufacturers and the experimental measurements of the commercial device. Another advantage of this model is that it can be easily exported to different simulation platforms. The proposed behavioural models have been validated with two commercial SSPC (DDC and Sensitron manufacturers). Finally, in this thesis have been developed two prototypes of SSPC. The final prototype allows verifying experimentally the different control strategies for connecting highly capacitive loads, using MOSFET technology. There have also been validated different SSPC functionalities, such as I2t protection, short circuit protection, thermal memory effect, etc. Moreover, there have been validated the structural and the behavioural model, based on the experimental measurements of the final prototype. Finally, the operating of the SSPC prototype based on IGBT technology has been also validated.
There is a strong trend in the new designs of military and civil aircraft towards the concept of more or fully electric aircraft. This is mainly due to the replacement of pneumatic and hydraulic systems by fully or partially electrical systems. The concept of more electric aircraft presents a series of advantages and improvements in comparison with conventional aircraft, from the point of view of efficiency, weight, volume, environmental impact, etc. In these new aircrafts the electrical power distribution systems (PDS) are the key element, principally due to the new requirements of demanded power and the required functionality. Therefore the new electrical systems have evolved towards new distribution architectures based on distributed systems, where traditional voltages levels at 28 VDC and 115 VAC, have been replaced by levels of 270 VDC, ±270 VDC and 230 VAC. Because of these new PDS, more electric aircrafts require a greater number of electronic equipments, such as converters, rectifiers, inverters and solid state protections, that allow to fulfil the needs arising from these new architectures. One of the key elements of these new PDS is the introduction of the solid state power controllers (SSPC) as elements of wiring protection and control of the electrical loads. These devices allow to replace the magneto-thermal and relays that are used in the conventional SDP, since these conventional devices present operational problems in the new PDS, due mainly to the changes in the voltage levels. Furthermore, the development of the new functionality and capabilities of the SSPC are related to: the configuration of the new PDS architectures, the elements that interact, their location within the architecture and the loads to which they connect. Within these systems, the connection of certain loads, such as the highly capacitive loads, imply the need to develop new control strategies to improve the process the connection of such loads. In this research, a detailed analysis of five procedures for connecting highly capacitive loads has been done. The five procedures are implemented with control circuits made with passive and active elements. Therefore, new methods have been presented in order to obtain the active control of the current through the SSPC, applicable during connection period, which allow the connection of highly capacitive loads. The active control methods developed within this thesis are the following: active control with constant current, active control with slope constant current, generalized active control and active control by optimum trajectory current. Each method has been defined by simple equations that allow to calculate the maximum capacitor that is possible to be charged during the connection, as a function of the nominal current, the maximum current and the value of the resistive component part of the load. Taking into the account the complexity of the new onboard PDS, the SSPC models play a fundamental role when the function of the components is being reproduced to anticipate potential problems of operating within the new architectures. However, SSPC manufacturers do not provide models of these devices. In order to analyze the effects of these new devices of the onboard systems, it is necessary to develop new models of SSPC, which allow, on one hand, predicting malfunctions and, on the other hand, detecting the effects inducted by the SSPC in PDS when integrated with the rest of the components. Thus, these models allow simplifying the process of validating the functionality of the whole system. Therefore, one of the goals outlined in the thesis has been the development of the models that allow to validate the behaviour of SSPC during the different stages of the development process and their further integration in the PDS. In this thesis two types of models have been presented, that are applicable to the SSPC. The first type is a structural model, and it is based on the internal structure of the SSPC. This model allows to detect problems during the design phases, before final assembly of the device. The second model, which has been proposed in the thesis, is based on the SSPC behavioural modelling. This model is divided in blocks, which are entirely independent of the of the SSPC internal structure. Therefore, it can be configured according to the datasheets provided by the manufacturers and the experimental measurements of the commercial device. Another advantage of this model is that it can be easily exported to different simulation platforms. The proposed behavioural models have been validated with two commercial SSPC (DDC and Sensitron manufacturers). Finally, in this thesis have been developed two prototypes of SSPC. The final prototype allows verifying experimentally the different control strategies for connecting highly capacitive loads, using MOSFET technology. There have also been validated different SSPC functionalities, such as I2t protection, short circuit protection, thermal memory effect, etc. Moreover, there have been validated the structural and the behavioural model, based on the experimental measurements of the final prototype. Finally, the operating of the SSPC prototype based on IGBT technology has been also validated.
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Keywords
Sistemas de distribución de potencia eléctrica, SDPE, Sistemas distribuidos, Controladores de potencia de estado sólido, SSPC, Aviones