Electrochemical deposition of cobalt alloy

Electrodeposition of cobalt alloys with refractory metals makes it possible to obtain coatings with a unique combination of physicochemical properties that are unattainable using other deposition methods. For the deposition of high-quality coatings with a cobalt-vanadium alloy, it is proposed to use a citrate electrolyte. Co-V coating was deposited on steel samples from citrate electrolyte at a temperature of 35-40 °C and a current density of 5-12 A/dm2 using soluble cobalt anodes. The vanadium content in the coating deposited at a ligand concentration of 0.3 mol / dm3 is 0.1-0.5 wt%. An increase in the concentration of the ligand to 0.4 mol / dm3 promotes the binding of cobalt into complexes, and, accordingly, the vanadium content in the coating increases to 0.6-1.2 wt.%. Moreover, the tendency to change the percentage of alloying elements with current density remains. Deposition coatings are dense, shiny, without internal stresses and cracks. The proposed compositions of electrolytes and modes of deposition of Co-V coatings with a vanadium content of up to 1.5 wt.% And a current efficiency of 50%. It was found that Co-V coatings are characterized by increased carbon content and are substitutional solid solutions, and the surface morphology of the obtained coatings depends significantly on the current density and changes from fine-crystalline to globular spheroid. The optimal current density for obtaining high-quality coatings with a cobalt alloy in a galvanostatic mode is ік = 10 A / dm2. Management of the storage of galvanic cobalt alloys in a quite wide range of concentrations of alloy-forming components is achieved by varying the electrolysis parameters, which allows the deposition technology to be adapted to the needs of the modern market.

A New Optimal Current Controller for a Three-Phase Shunt Active Power Filter Based on Karush–Kuhn–Tucker Conditions

This paper presents an algorithm for finding the optimal control for a current controller that operates as a part of a control system of a shunt active power filter. The algorithm is based upon the Karush–Kuhn–Tucker conditions for finding an optimal value where control signal is limited and constraints create a cube. The explicit solution of the Karush–Kuhn–Tucker problem is presented and simplified calculations are given to lower calculation complexity. The presented Karush–Kuhn–Tucker algorithm is compared with a classical PI controller. It is given the algorithm for finding the optimal parameters of the PI controller and the behavior of the PI controller is compared with the presented algorithm. Attention has been paid to the saturation of controllers in commutation states of load currents, which has a negative impact on the final performance of the controllers and the controlled shunt active power filter. The paper also presents the software and hardware platforms applied to run the presented algorithms in real-time. For both controllers, the shunt active power filter response is shown using real experimental results. The results of the experiments prove better behavior regarding the presented algorithm, especially in the case of commutative load currents, where the output signals from other regulators become saturated.

Linear PWM Techniques of Asymmetrical Six-phase Machine With Optimal Current Ripple Performance

<p>Linear modulation techniques (LMTs) of an asymmetrical six-phase machine (ASPM) with two isolated neutral points synthesize the desired voltage vectors by applying at least five switching states. Different choices of applied voltage vectors, sequences in which they are used, distribution of dwell times among the redundant switching states give rise to a large number of possible LMTs. It is desirable that these LMTs avoid more than two transitions of a particular inverter leg within a carrier period. Only a subset of existing LMTs of ASPM follows this rule. Through an innovative approach, this paper finds a way to account for all possible infinitely many LMTs that follow the rule of at most two transitions per leg. Another important criterion for the selection of an LMT is its current-ripple performance. Therefore, through numerical optimization, the paper finds optimal LMTs among the above infinite possible LMTs for all reference voltage vectors in the linear range and for the whole feasible range of a machine parameter. This parameter is related to the leakage inductance of the machine and impacts the current ripple performance of ASPM. An optimal hybrid strategy is proposed with these optimal techniques, which outperforms all existing techniques in terms of the current ripple. The theoretical analysis is validated through simulation in Matlab and experiments performed up to 3.5 kW on a hardware prototype.</p>

Linear PWM Techniques of Asymmetrical Six-phase Machine With Optimal Current Ripple Performance

<p>Linear modulation techniques (LMTs) of an asymmetrical six-phase machine (ASPM) with two isolated neutral points synthesize the desired voltage vectors by applying at least five switching states. Different choices of applied voltage vectors, sequences in which they are used, distribution of dwell times among the redundant switching states give rise to a large number of possible LMTs. It is desirable that these LMTs avoid more than two transitions of a particular inverter leg within a carrier period. Only a subset of existing LMTs of ASPM follows this rule. Through an innovative approach, this paper finds a way to account for all possible infinitely many LMTs that follow the rule of at most two transitions per leg. Another important criterion for the selection of an LMT is its current-ripple performance. Therefore, through numerical optimization, the paper finds optimal LMTs among the above infinite possible LMTs for all reference voltage vectors in the linear range and for the whole feasible range of a machine parameter. This parameter is related to the leakage inductance of the machine and impacts the current ripple performance of ASPM. An optimal hybrid strategy is proposed with these optimal techniques, which outperforms all existing techniques in terms of the current ripple. The theoretical analysis is validated through simulation in Matlab and experiments performed up to 3.5 kW on a hardware prototype.</p>

Peningkatan Kinerja Switched Reluctance Generator dengan Pergeseran Sudut Penyalaan

ABSTRAKDewasa ini teknologi energi terbarukan biasanya menggunakan mesin listrik sinkron Alternating Current (AC) pada pembangkit listrik tenaga angin. Generator listrik sinkron AC menggunakan brush pada proses eksitasi yang membutuhkan perawatan berkala sehingga rumit jika diaplikasikan pada Pembangkit Listrik Tenaga Angin. Pada penelitian ini generator akan menggunakan mesin Switched Reluctance yang dioperasikan sebagai Switched Reluctance Generator (SRG). Untuk menghasilkan keluaran arus yang optimal, SRG akan dioperasikan dengan mengatur sudut penyalaan fasa menggunakan metode single pulse. Metode pensakelaran ini diatur oleh input capture fasilitas mikrokontrol dsPIC 30F4012. Penelitian ini telah diverifikasi dengan simulasi Simulink MATLAB dan pengujian alat. Hasil pengujian optimal dibuktikan pada sudut penyalaan θon = 40 derajat dan θoff = 170 derajat menghasilkan arus discharging sebesar 7.6 A dengan kecepatan 1647.1 RPM ditandai dengan bentuk gelombang arus yang ideal. Hasil arus discharging yang optimal dapat meningkatkan kinerja SRG, sehingga metode ini dapat diaplikasikan pada pembangkit listrik tenaga angin.Kata kunci: SRG, dsPIC30F4012, sudut penyalaan, single pulse ABSTRACTNowadays, renewable energy technology usually uses AC synchronous electric machines in wind power. AC synchronous generator uses a brush in the excitation process, which requires periodic maintenance so it is complicated if applied to wind power. In this research, the generator will use a Switched Reluctance machine that operated as a SRG. To produce an optimal current, the SRG will be operated by adjusting the ignition angle using the single pulse method. This method is controlled by input capture of the microcontroller dsPIC 30F4012. This research has been verified by simulating Simulink MATLAB and testing device. The optimal test results are proven at the ignition angle θon = 40 degree and θoff = 170 degree produces a discharging current of 7.6 A with a speed of 1647.1 RPM characterized by the ideal current waveform. The optimal discharging current results can improve the performance of the SRG, so this method can be applied to wind power.Keywords: SRG, dsPIC30F4012, the ignition angle, single pulse

Variasi Temporal Karakteristik Arus di Perairan Tanjung Jati Kabupaten Jepara

The waters of Tanjung Jati, Jepara Regency, are quite strategic areas due to the utilization of the coastal areas and waters. One water parameter that is important to study and has a high enough influence on other parameters is ocean currents. The purpose of this study is to determine the characteristics of the ocean currents that occur in the waters of Tanjung Jati, by temporal variation in 2020 and 2021. The results show that the smallest current velocity is in the most basic layer; this is likely due to the influence of the friction force on the bottom of the water, while the greatest velocity is on the layer near the surface. Current characteristics show a relationship between current velocity, current direction, and water level that occurs in each layer of water. This relationship can be seen by the decrease in current velocity at the lowest tide and the highest tide, and vice versa. The current velocity increases at low tide. The highest optimal velocity at low tide towards tide compared to tidal currents towards ebb. The direction of this optimal current is northeast. The movement of the current at tide towards the ebb is towards the West - Southwest, while the current movement during the tide towards the tide is towards the East - Northeast direction. The direction of the dominant current that occurs in the waters of Tanjung Jati B, Jepara, is towards the East-Northeast domination at low tide and towards the West-Southwest domination at low tide. Details on the current characteristics of each layer in 2020 and 2021 have not changed significantly. Kawasan perairan Tanjung Jati Kabupaten Jepara merupakan Kawasan yang cukup strategis dikarenakan pemanfaatan wilayah pesisir maupun perairannya. Terkait hal tersebut, sal;ah satu parameter perairan yang penting untuk diteliti dan mempunyai pengaruh cukup tinggi terhadap parameter lainnya adalah arus laut. Tujuan penelitian ini adalah mengetahui karakteristik arus laut yang terjadi di perairan Tanjung Jati, secara variasi temporal tahun 2020 dan 2021. Hasil penelitian menunjukkan Kecepatan arus terkecil berada pada layer paling dasar hal ini kemungkinan terjadi karena pengaruh gaya gesek dengan dasar perairan, sedangkan kecepatan paling besar berada pada layer dekat permukaan. Karakteristik arus seperti yang terlihat menunjukan adanya hubungan antara kecepatan arus, arah arus dengan elevasi air yang terjadi pada setiap lapis air. Hubungan ini dapat dilihat dengan adanya penurunan kecepatan arus pada saat muka air surut terendah dan pasang tertinggi dan sebaliknya kecepatan arus meningkat pada saat pasang menuju surut. Kecepatan optimal tertinggi pada saat arus surut menuju pasang dibandingkan dengan arus pasang menuju surut. Arah arus optimal ini adalah timur laut. Pergerakan arus pada saat pasang menuju surut adalah ke arah Barat – Barat Daya sedangkan pergerakan arus pada saat surut menuju pasang adalah ke arah Timur – Timur Laut. Arah arus dominan yang terjadi di kawasan Perairan Tanjung Jati B, Jepara adalah ke arah dominasi Timur- Timur Laut pada saat surut menuju pasang dan ke arah dominasi Barat-Barat Daya pada saat air pasang menuju surut. Detil pada karakteristik arus tiap layer pada tahun 2020 dengan 2021 tidak mengalami perubahan secara signifikan.