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In this work it is presented a two-phase open-end winding induction motor (IM) driven by an improved current source inverter (CSI). The proposed inverter has independent full quadrant operation, lower DC-link current value, high magnetics power density, 25% more efficient and high AC output voltage waveform quality compared to conventional CSI solutions. A back-to-back AC-DC-AC current source converter...
DC fault protection is one of the biggest challenge to multi-terminal direct current (MTDC) systems, because DC current has no natural zero crossing point. To overcome this problem, hybrid DC circuit breaker (DCCB), which serves as a promising solution to the isolation of DC faults, has been developed. However, hybrid DCCB contains a huge number of power semiconductors, which is costly and inefficient...
This paper presents the experiences gained from the introduction of Problem-based learning (PBL) in Power Electronics course at the Universiti Tenaga Nasional (Uniten), Malaysia. Power Electronics is a fast developing technology within the electrical engineering field. To cope with the advances industrial practices need to be integrated in the theoretical knowledge. This work combined traditional...
This paper proposes a new protection scheme for the HVDC circuit, which is based on the MMC topology with the double thyristor switches sub-modules. Although the MMC with double thyristor switches in each sub-module has the ability to clear the short circuit fault, the duration of AC and DC short circuit currents is not controllable. Former work solved the problem of the long duration of the AC short...
A modified Marx-based solid-state topology for supplying inductive loads is presented. The basic principle of charging capacitors in parallel and discharging them in series is conserved. Due to the negative di/dt phase the inductive load imposes a reversible voltage power converter. Furthermore, in some applications such as eddy current septum magnets a negative current is required as well. The presented...
The Modular Multilevel Converter (MMC) topology has become one of the most promising solution in HVDC applications when compared with similar approaches. The evaluation of the power losses in an MMC terminal is fundamental to estimate the overall converter efficiency and size the required thermal management system. In this paper, a complete comparison of two methods to calculate conduction and switching...
The average-value model (AVM) of the modular multilevel converters (MMCs) is the simplified one for the average response of switching devices, converters and control. The effect of sub-module capacitor voltage ripple on the MMC dynamic behavior is explored and an accurate average-value model of MMCs is established. Based on the proposed AVM, the equivalent impedances of the DC and AC sides in the...
Modular multilevel converter (MMC) has become a prominent converter topology used in HVDC transmission systems over the past decade. The efficiency, size and system performance are the main factors of the HVDC converter stations which directly affect the converter performance end-cost. Replacing conventional half-bridge (HB) cells by full-bridge (FB) cells in the MMC arms offers new features such...
This paper presents a control strategy of modular multilevel converter which produces variable DC output from a three phase AC source. With this proposed strategy the output DC voltage of the converter can be bidirectional (i.e. both positive and negative) and can be varied to a value higher than the peak input voltage (boost), or to a value lower than the peak input voltage (buck). A simple synchronous...
This paper compares the effects of ring, radial and interconnected DC grid topologies on the transient stability of a segmented 15 - bus electric grid for different HVDC schemes. For this purpose, three HVDC convertor technologies and four HVDC station configurations are considered. A three phase AC bus fault is applied and the rotor angle disturbance is analyzed. The results show that the transient...
HVDC transmission technology is an efficient alternative for bulk power transmission over long distances and is used for subsea electrical transmission and interconnection of asynchronous ac grids. Converters play an important role in HVDC transmission systems. Here a Bidirectional Buck Boost Inverter based HVDC (BBI-HVDC) transmission system is presented. The output voltage and current of the new...
This paper investigates the effect of two HVDC grid segmentation topologies i.e. hybrid HVAC-HVDC and standalone HVDC on the transient stability of a 15-bus electric grid. For this purpose, four HVDC station configurations and three HVDC technologies are considered. A three phase AC fault is applied at one of the buses and the rotor angle of one of the generators is analyzed. The results show that...
The topology of modular multilevel converters (MMC) is investigated in this paper. First, single phase half bridge inverter with split wound coupled inductors was studied, it was found that more voltage levels can be generated by using split wound coupled inductors. Therefore, new MMC topology was proposed by the analysis result, therein, two more diodes were used for each arm, and split wound coupled...
The modulation technique chosen for use in the power converter largely defines the harmonics generated, consequently it is a fundamental part that must be studied. In this paper it's shown a comparative between different modulations techniques applied to a modular multilevel converter. Sinusoidal Pulse Width Modulation, Space-Vector Modulation and Nearest Level Modulation are studied. The whole techniques...
The modular multilevel converter (MMC) is one of the most promising converter topologies for medium/high-power applications. One of the technical challenges associated with the control of an MMC is the capacitor voltage balancing among arm capacitors. This paper presents a novel capacitor voltage balancing method combined with the carrier-phase-shifted pulse-width modulation (CPS-PWM) for MMC without...
This paper presents a detailed state-space modeling of a Modular Multilevel Converter (MMC) in combination with line frequency transformer (LFT). The classical MMC topology is compared with the recently proposed Open-End Winding MMC (OEWMMC) topology, which integrates the LFT in the converter arm. The line frequency transformer parameters are added in the model, some of which are often neglected in...
This paper presents a new control method for a Modular Multilevel Converter (MMC) fed by a push-pull converter via a medium frequency (MF) transformer. Application of this topology is a universal high-precision 3AC voltage source for a Power Hardware-in-the-Loop Emulator with a frequency range from DC up to almost the medium frequency. Advantages are high efficiency, very low harmonic distortion and...
The Modular Multilevel Converter (M2LC) is a well-known modular multilevel topology. This paper proposes a novel branch inductor coupling and compares it to the center-tapped inductor and the standard non-coupled inductor topology. The proposed coupling has a significant influence on the inductor and converter dimensioning. Its properties make it especially well-suited for use in M2LC single-to-three-phase...
This paper investigates design procedure of modular multilevel converter (MMC) in active front-end (AFE) mode of operation. The design in performed trying to minimize the amount of passive elements including arm inductances and submodule capacitances. This has been done using basic controllers needed for operation of MMC in AFE mode, without employing any additional controller in the circuit. In other...
Modular Multilevel Converter (MMC) has recently become a popular multilevel topology for high-power applications. Conventionally, the circulating current between the legs of an MMC is an unwanted current that must be minimized in order to reduce the converter loading. In this paper the impacts of the circulating current in the MMC to the current ratings of power semiconductor devices are comprehensively...
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