Current Issue : April - June Volume : 2017 Issue Number : 2 Articles : 5 Articles
In electrical power converter systems, the presence of an LC input filter can efficiently\nreduce the Electromagnetic Interference (EMI) effect, and at the same time protect the converter\nand the load from being impacted by sharp input impulse voltages. However, for transportation\napplications, the weight and size limitations of input LC filters for power converters have to be\ntaken into consideration. The reduction of LC filter size may impair the system stability margin and\ndynamic response. In serve cases, the system may even become unstable. Thus, in order to ensure\nthe system stability while minimizing the input LC filter size, the implementation of a stabilizer for\nthe system control is needed. In this paper, a novel digital stabilizer design method is proposed for\na boost power converter with a small input LC filter. The proposed method is based on input filter\ninductance current measurements and DSP (Digital Signal Processor) -based digital stabilizer design.\nSimulation and experimentation confirm the validity of the proposed approach....
An active gate controlled semiconductor protection switch using SiC-MOSFET is proposed to achieve the fault tolerant operation\nof ISOP (Input Series and Output Parallel) connected multicell dc-dc converter.The SiC-MOSFET with high temperature capability\nsimplifies the configuration of the protection circuit, and its on-resistance control by the active gate controller realizes the smooth\nprotection without the voltage and the current surges.The first laboratory prototype of the protection switch is fabricated by using\na SiC-MOSFET with a high frequency buck chopper for the active gate controller. The effectiveness of the proposed protection\nswitch is verified, taking the impact of the volume reduction into account....
The microgrid system is an answer to the necessity of increasing renewable energy\npenetration and also works as a bridge for the future smart grid. Considering the microgrid system\napplied to commercial building equipped with photovoltaic sources, the usage of a DC microgrid\narchitecture can improve the efficiency of the system, while ensuring robustness and reducing the\noverall energy cost. Given the power grid stress and the intermittency of the DC microgrid power\nproduction, backup power provision and load shedding operations may occur to stabilize the DC\nbus voltage. Based on the knapsack problem formulation, this paper presents a realistic optimization\napproach to shedding a building�s appliances, considering the priority of each appliance, and also\nconsidering a minimum amount of load that must be attended. The problem is solved by mixed\ninteger linear programming and the CPLEX solver. The proposed architecture ensures critical load\nsupply and voltage stabilization through the real-time operation of the operational algorithm allowing\nthe load shedding optimization approach to be applied without compromising the robustness of\nthe system. The results obtained by simulation prove that the DC microgrid is able to supply the\nbuilding power network by applying the load shedding optimization program to overcome, mainly,\nthe renewable energy intermittency....
This paper proposes a DC fault protection strategy for large multi-terminal HVDC (MTDC) network where MMC\nbased DC-DC converter is configured at strategic locations to allow the large MTDC network to be operated\ninterconnected but partitioned into islanded DC network zones following faults. Each DC network zone is protected\nusing either AC circuit breakers coordinated with DC switches or slow mechanical type DC circuit breakers to\nminimize the capital cost. In case of a DC fault event, DC-DC converters which have inherent DC fault isolation\ncapability provide ââ?¬Ë?firewallââ?¬â?¢ between the faulty and healthy zones such that the faulty DC network zone can be\nquickly isolated from the remaining of the MTDC network to allow the healthy DC network zones to remain\noperational. The validity of the proposed protection arrangement is confirmed using MATLAB/SIMULINK simulations....
Nowadays, due to excellent advantages of permanent magnet brushless (PMBL) motors such as high efficiency and high\ntorque/power density, they are used in many industrial and variable-speed electrical drives applications. If the fabricated PMBL\nmotor has neither ideal sinusoidal nor ideal trapezoidal back-EMF voltages, it is named nonideal (or nonsinusoidal) PMBL motor.\nEmploying conventional control strategies of PMSMs and BLDCMs lowers the efficiency and leads to unwanted torque ripple,\nvibration, and acoustic noises. Moreover, in many applications to reduce the cost and enhance the reliability of drive, sensorless\ncontrol techniques are used. This paper proposes a novel sensorless control for a nonsinusoidal PMBL motor with minimum torque\nripple. To develop smooth torque, the selected torque harmonic elimination strategy is employed. Furthermore, to estimate the rotor\nposition and speed, a novel full-order sliding mode observer is designed. Proposed observer estimates the position and speed of\nmotor from standstill to final speed. The proposed observer is robust to uncertainty of harmonic contents in phase back-EMF\nvoltage and able to run the motor from standstill with closed-loop control scheme.The capabilities of torque ripple minimization\nand sensorless strategies are demonstrated with some simulations....
Loading....