Journal of Electrical Engineering & Technology

Electric vehicle (EV) is developed because of its environmental friendliness, energy-saving and high efficiency. For improving the performance of the energy storage system of EV, this paper proposes an energy management strategy (EMS) based model predictive control (MPC) for the battery/supercapacitor hybrid energy storage system (HESS), which takes stabilizing the DC bus voltage and improving the efficiency of the system as two major optimization goals. In addition, an enumeration algorithm is presented to solve the optimization function. The experimental results show the performance of the proposed EMS which is able to enhance the overall instantaneous power and prevent the battery from overloading. Meanwhile, compared with the results of a single battery storage system, the maximum amplitude of the battery current in the HESS is reduced by 40.81% and whole system energy loss is reduced by 24.13% with the proposed power management strategy.

In this paper, a novel discrete terminal integral sliding-mode backstepping control (DTISM-BSC) is proposed for the surface-mounted permanent magnet synchronous motor (SMPMSM) drive system, which improves the speed tracking performance and robustness of the system. In this control scheme, the discrete ultra-local model (ULM) of the SMPMSM drives, which employs the algebraic parameter identification technology to handle the unknown disturbance and parametric uncertainties, is first set up. Then, the terminal integral sliding-mode surface is proposed for its advantages of finite-time convergence to achieve speed rapid tracking, in which the control performance of backstepping control is improved. Thirdly, the equivalent control law is combined with the designed switching law to construct the speed controller based on the ULM. In this case, the bounded function is adopted to improve chattering problem. Meanwhile, the asymptotic stability and rapid convergence is verified. Finally, the experimental comparisons between the proposed method and the non-singular terminal sliding mode backstepping control (NTSM-BSC) are developed to validate the effectiveness of the proposed DTISM-BSC.

This paper proposes a control algorithm for solving the unbalanced current of the primary side in an LLC converter that uses a center-tap rectifier on the secondary side in ultra-high definition TV applications. The current imbalance in the LLC converter using a center-tap rectifier causes thermal problems, low efficiency, and uncontrollability. The operational principle, primary side control algorithm, and design equation required to solve these problems are presented. The experimental results are presented to verify the efficiency and thermal improvement of proposed control algorithm.

Solution processable metal oxide semiconductors offer opportunities for large area fabrication of transparent logic circuits without requiring expensive vacuum equipment. Indium zinc oxide (IZO) is one of the more popular research targets for use as active layer in thin-film transistors (TFTs). In this paper, we present our results on the fabrication of TFTs with IZO semiconductor film using spin-coating from the 1:1 molar ratio mixed solution of indium nitrate and zinc carbonate. We optimize the device fabrication process by studying the effect of stacking multiple layers on top of each other. The electrical characteristics of the TFTs are found to depend strongly on the number of the spin coating steps employed. The practical applicability of the TFTs is also demonstrated by fabricating a load-type inverter circuit and measuring its electrical response, modeling operation in digital circuitry.

The suggested work in this paper involves the construction of digital filters by utilizing optimization algorithms to compute optimum filter coefficients in such a way that the designed filter's magnitude response is identical to the ideal one. The proposed work takes a nature-inspired approach to optimizing the design of 20th order linear phase finite impulse response (FIR) based low pass, high pass and band pass filters. This approach involves the cuckoo search optimization algorithm (CSA) and Grasshopper optimization algorithms (GOA) by minimizing the least mean square error function and L1-norm based ones. These GOA and CSA are used to find the best possible values for the filter coefficients. The bench mark algorithm to design the FIR filter as Parks–McClellan approach and other recently published optimization algorithms are used to prove the superiority of proposed designs. Compared with PM method, real coded genetic algorithm, Cat swarm, Particle swarm optimization and some hybrid optimization based ones, the proposed design results have been outperform. Moreover, the proposed FIR filters give the best outcome, effectively meeting the target with decreased pass band ripples and higher attenuation in the stop band with a least execution time.

When supplying natural gas, KOGAS intends to utilize the new energy by installing a system that runs the generator using the energy generated when the high-pressure natural gas is reduced to low pressure, that is, TEG. In the past, the energy generated by decompressing natural gas in the supply management station was thrown into the air, but by using this to generate electricity, high-quality new energy that does not emit greenhouse gases and consumes fuel is obtained. This paper examines the characteristics of TEG power generation, examines the TEG pilot project and demonstration project conducted by Korea Gas Corporation, and discusses the voltage control scheme and grid interconnection.

In this study, we fabricated TN-LCD using DuoPIGatron ion beam with obliquely irradiated polyimide film and TN-LCD using conventional rubbing method, and compared the electro-optic characteristics. In the TN-LCD using the rubbing method, a pretilt angle of 0.05° was obtained, and it was confirmed that an excellent pretilt angle of 1.13° also occurred in the TN-LCD irradiated with an ion beam. In addition, voltage-transmittance characteristic, which is a characteristic for realizing gray scale, was measured using the TN-LCD manufactured as described above. And, the response time characteristic was measured as a basic feature to compose a screen without motion blur. As a result, both the TN-LCD using the rubbing method and the TN-LCD manufactured by ion beam irradiation showed good voltage-transmittance characteristics in the driving voltage range of 1.5–3.5 V. In particular, as a result of measuring the response time characteristics, the light-on time was measured at 5.11 ms and the light-off time was measured at 10.98 ms. This is a very good result at the level of TN-LCD without chiral dopant, which can be evaluated as comparable with the result of the production level.