Cascade multilevel inverters have been developed for electric utility applications. A cascade M level inverter consists of (M 1)/2 H bridges in which each bridge's dc voltage is supported by its own dc capacito...Cascade multilevel inverters have been developed for electric utility applications. A cascade M level inverter consists of (M 1)/2 H bridges in which each bridge's dc voltage is supported by its own dc capacitor. The new inverter can: (1) generate almost sinusoidal waveform voltage while only switching one time per fundamental cycle; (2) dispense with multi pulse inverters' transformers used in conventional utility interfaces and static var compensators; (3) enables direct parallel or series transformer less connection to medium and high voltage power systems. In short, the cascade inverter is much more efficient and suitable for utility applications than traditional multi pulse and pulse width modulation (PWM) inverters. The authors have experimentally demonstrated the superiority of the new inverter for power supply, (hybrid) electric vehicle (EV) motor drive, reactive power (var) and harmonic compensation. This paper summarizes the features, feasibility, and control schemes of the cascade inverter for utility applications including utility interface of renewable energy, voltage regulation, var compensation, and harmonic filtering in power systems. Analytical, simulated, and experimental results demonstrated the superiority of the new inverters.展开更多
The operation of a motor drive for high-power, high-speed applications, especially for the permanent-magnet synchronous AC motors with regeneration capability is presented. Power system utilizes a SVHPWM （space-vecto...The operation of a motor drive for high-power, high-speed applications, especially for the permanent-magnet synchronous AC motors with regeneration capability is presented. Power system utilizes a SVHPWM （space-vector-based hybrid pulse width modulation） for a reduced harmonic distortion and switching loss. Associated electromagnetic interference mitigation and cooling requirements are significantly reduced. Voltage source inverter drives a three-phase MLC200 flywheel. The modularity of the proposed topology also simplifies overall system design and manufacturability. The system topology and control strategy are discussed. Simulation results are presented to illustrate the harmonic distortion and switching loss reduction and reduced line current ripple.展开更多
Herein, we present a case of pneumoaorta and aorto-duodenal fistula (ADF) caused by an endoluminal aortic prosthesis infection. An 82-year-old man underwent endovascular aneurysm repair with a stent graft to exclude a...Herein, we present a case of pneumoaorta and aorto-duodenal fistula (ADF) caused by an endoluminal aortic prosthesis infection. An 82-year-old man underwent endovascular aneurysm repair with a stent graft to exclude a 5.1-cm abdominal aortic aneurysm. Three months after the index procedure, the patient was taken to the emergency department at a medical university hospital. He presented with a 2-d history of bloody diarrhea. An endoluminal aortic stent graft infection was diagnosed, and an ADF was identified. The patient died of septic shock despite emergency surgery and intensive care. When encountered, stent graft infections require appropriate antibiotics and graft explantation.The diagnosis of an ADF is important, and surgery remains the most effective management if septic shock presents despite conservative treatment.展开更多
文摘Cascade multilevel inverters have been developed for electric utility applications. A cascade M level inverter consists of (M 1)/2 H bridges in which each bridge's dc voltage is supported by its own dc capacitor. The new inverter can: (1) generate almost sinusoidal waveform voltage while only switching one time per fundamental cycle; (2) dispense with multi pulse inverters' transformers used in conventional utility interfaces and static var compensators; (3) enables direct parallel or series transformer less connection to medium and high voltage power systems. In short, the cascade inverter is much more efficient and suitable for utility applications than traditional multi pulse and pulse width modulation (PWM) inverters. The authors have experimentally demonstrated the superiority of the new inverter for power supply, (hybrid) electric vehicle (EV) motor drive, reactive power (var) and harmonic compensation. This paper summarizes the features, feasibility, and control schemes of the cascade inverter for utility applications including utility interface of renewable energy, voltage regulation, var compensation, and harmonic filtering in power systems. Analytical, simulated, and experimental results demonstrated the superiority of the new inverters.
文摘The operation of a motor drive for high-power, high-speed applications, especially for the permanent-magnet synchronous AC motors with regeneration capability is presented. Power system utilizes a SVHPWM （space-vector-based hybrid pulse width modulation） for a reduced harmonic distortion and switching loss. Associated electromagnetic interference mitigation and cooling requirements are significantly reduced. Voltage source inverter drives a three-phase MLC200 flywheel. The modularity of the proposed topology also simplifies overall system design and manufacturability. The system topology and control strategy are discussed. Simulation results are presented to illustrate the harmonic distortion and switching loss reduction and reduced line current ripple.
文摘Herein, we present a case of pneumoaorta and aorto-duodenal fistula (ADF) caused by an endoluminal aortic prosthesis infection. An 82-year-old man underwent endovascular aneurysm repair with a stent graft to exclude a 5.1-cm abdominal aortic aneurysm. Three months after the index procedure, the patient was taken to the emergency department at a medical university hospital. He presented with a 2-d history of bloody diarrhea. An endoluminal aortic stent graft infection was diagnosed, and an ADF was identified. The patient died of septic shock despite emergency surgery and intensive care. When encountered, stent graft infections require appropriate antibiotics and graft explantation.The diagnosis of an ADF is important, and surgery remains the most effective management if septic shock presents despite conservative treatment.
