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A reliable multilevel inverter with fault tolerance is proposed. It consists of two sources and six switches. The unipolarity voltage level produced by the proposed inverter is transformed to dual polarity with the help of H-bridge. The proposed inverter produces maximum 9 levels output voltage with asymmetrical source and 5 levels output voltage with symmetrical source in healthy condition. During...
The Cascaded multilevel inverters are popular in high-power medium-voltage drives because of their modularity and high power handling capacity. An efficient, systematic fault detection scheme is necessary for the reliable operation of the drive. In this paper, a novel open switch fault diagnosis for the three-phase cascaded H-bridge inverter-fed induction motor drive based on the discrete wavelet...
In this paper a novel and fast open-circuit fault detection and localization method is proposed for Five-level active-neutral-point-clamped (5L-ANPC) converter. The method is based on comparing the measured output voltage with the reference voltage and the voltage obtained from the fault analysis. The implementation scheme of the method is presented; and all the practical aspects including capacitors...
This paper deals with the interruption scheme designed using Vacuum Circuit Breaker (VCB) based on zero crossing characteristics, implemented electromechanically for High Voltage Direct Current (HVDC) system. The operation is carried out using Mechanical scheme as it has minimum energy loss in comparison to Solid-State and Hybrid schemes. The Mechanical scheme consists of series connection of multiple...
Battery energy storage system based on modular multilevel converter (MMC-BESS) has many advantages such as easy expansibility and high reliability. With multiple submodules (SM), the corresponding SM fault ride-through method is mandatory to reduce the construction redundancy and improve the operational reliability. This paper proposes a redistributed pulse width modulation (R-PWM) method for MMC-BESS...
This paper proposes an adaptive democratic current sharing control scheme for interleaved dc-dc converters under faulty condition. The proposed fault tolerant control approach can achieve the desired output voltage generation, and equal current sharing among the remaining healthy modules as more and more modules fail. The main idea is to adaptively change the outer voltage and inner current controller...
Nowadays, research on the reliability improvement of T-type three-level inverters is studied as an important issue. In this paper, a novel fault tolerant control strategy based on model predictive control (MPC) is proposed for open-circuit faults in switch devices. When an open-circuit fault occurs to neutral-point switches, the impossible switching states of zero- and small-voltage vectors should...
Many control and monitoring applications including thermostats, doorbells, and security systems utilize 60 Hz transformers with grid-voltage inputs and 16 V to 24 V ac outputs. The new DOE Level VI efficiency standard places stringent requirements on the no-load quiescent loss of grid-interface power supplies, including these low-voltage transformers. This paper explores a low-cost but highly effective...
This paper proposes a transformer based self-starting boost converter for thermoelectric energy harvesting, which operates even when polarity inversion of thermoelectric generator (TEG) occurs. TEG is used to convert thermal energy into electrical energy. Due to the Seebeck effect, an open circuit voltage of the TEG is proportional to the number of thermocouples in series and to the temperature difference...
A novel modification of the Z-source circuit breaker topology is presented for low voltage applications. An ultra-fast mechanical switch has been used in place of the solid-state switch (thyristor) in the Z-source circuit breaker to reduce the energy loss utilizing the very low resistance of mechanical contactors. The proposed modification also facilitates bi-directional current flow for distributed...
A general fault diagnosis method is proposed for modular dc-dc converter system. The magnetic component voltage in each module is chosen as diagnostic signal, which can be easily obtained by adding an auxiliary winding into each magnetic core. Based on the feature of these signals, two logical hardware circuits are designed to achieve fast fault detection for different demands. Fault can be detected...
Since the traditional half-bridge modular multilevel converter (HB-MMC) is endangered under DC side short-circuit faults. This paper proposes a novel sub-module (SM) topology for MMC with DC fault limitation capability. The fault current is fully transferred to the bypass thyristor by turning off all IGBTs when DC short-circuit fault occurs, then the diode freewheeling effect is eliminated and all...
Due to the advantages of cost, volume and efficiency, transformerless grid-connected power converters have drawn an increasing attention, especially in low-power PV applications. However, the lack of isolation between inverter and grid brings in some potential risks to the distribution network. Among them, the dc injection flows into the grid remains a significant concern. Owing to the offset and...
This paper proposes a new modular multilevel converter with symmetric bidirectional DC fault blocking capability for high voltage direct current transmission systems. The new modular multilevel converter is composed of novel submodules, which is developed from a three-level T-type converter combined with some clamp circuits. The proposed novel submodule can output three voltage levels with six IGBTs,...
Fault tolerant operation can significantly improve the reliability of a Modular Multilevel Converter (MMC), but the precondition is that a fast and accurate fault detection and localization method has been embedded into the MMC control system. This paper proposes a fault diagnosis method used in a distributed control architecture, which makes the local controllers capable of identifying the switching...
In this paper, a method to diagnose and identify the open-circuit faults of IGBT for a six-level hybrid inverter (6L-HI) is proposed, which is based on the signals of the inner device voltages, the flying capacitor voltages and the phase currents of the inverter. Since the flying capacitor voltage sensors and the output current sensors are already employed for the inverter operation, only one additional...
The interleaved bidirectional DC-DC converter is a core component of the battery energy storage system. However, if an open-switch fault occurs at the interleaved bidirectional DC-DC converters, the currents of two branches will become unbalanced, which will increase the battery current ripple and shorten the life of batteries and energy storage systems. In this paper, a fault tolerant topology is...
The amount of switching operations of unloaded transformers increases with the developments of smart grids and integration of renewable energy sources. A random energization of an unload transformer can cause high amplitude and high frequency inrush currents. Controlled switching can eliminate the inrush currents effectively, the key to realize which is measuring residual flux in transformer core...
DC circuit breakers (DCCBs) are an essential component for protecting multi-terminal HVDC transmission systems. DCCBs are required to have rapid fault clearing and high current interruption, as well as low power loss under normal operation. A hybrid DCCB constituted of a semiconductor breaker and a mechanical switch was investigated to achieve rapid fault clearing, within 3 ms, and interruption of...
Active neutral point clamped (ANPC) converter was developed in order to improve the performances of the neutral point clamped (NPC) converter in terms of the semiconductor loss distribution. Loss distribution depends primarily on modulation type used for generation of the switching signals, therefore it is important to find the appropriate modulation type that will allow the most uniform loss distribution...
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