Performance Modelling and Design Techniques for Efficiency Improvement in On-chip Switched-Capacitor DC-DC Converter

Fundamental charge vector method analysis is a single parameter optimization technique limited to conduction loss assuming all frequency-dependent switching (parasitic) loss negligible. This paper investigates a generalized structure to design DC-DC SC converters based on conduction and switching loss. A new technique is proposed to find the optimum value of switching frequency and switch size to calculate target load current and output voltage that maximize the efficiency. The analysis is done to identify switching frequency and switch size for two-phase 2:1 series-parallel SC converter for a target load current of 2.67mA implemented on a 22nm technology node. Results show that a minimum of 250MHz switching frequency is required for target efficiency more than 90% and the output voltage greater than 0.85V where the switch size of a unit cell corresponds to 10Ω on-resistance. MATLAB and PSpice simulation tools are used for results and validation.

Pengembangan Nominal Aturan Fuzzy pada Metode Fuzzy Mamdani untuk Menyeimbangkan Beban Tiga Phasa pada Saluran Distribusi Tegangan Menengah

The use of electrical equipment on the customer side with low voltage absorbs unbalanced power. The load unbalances in each phase will result in an unbalanced current, resulting in a phase voltage shift in the secondary coil of the 20 kV/380 V medium voltage transformer. Shifting the voltage in the distribution transformer phase, then causes the flow of current in the transformer neutral wire causing losses. This paper proposes a fuzzy logic method with the Mamdani fuzzy inference system (FIS) to balance three-phase load currents at seven feeders of 20 kV medium voltage distribution at PLN Rayon Taman Jawa-Timur. The feeders are Ngelom, Tawang Sari, Geluran, Bringin, Masangan Kulon, Palm Residence, and Pasar Sepanjang. There are three input variables used, namely the load current in phase R, phase S, and phase T respectively. There are three output variables in one FIS block, namely changes in load current in phase R, phase S, and phase T respectively. With the number of fuzzy rules as many as 509 rules, the proposed method is able to produce the lowest load current unbalance value of 1.6% at Palm Residence Feeders. The development of a nominal (number) of fuzzy rules in the Fuzzy Logic Method with FIS Mamdani is able to reduce the value of unbalance load current at the 20 kV medium voltage distribution feeder better than the method proposed by previous researchers.

Nonlinear load influence on single-phase fault current in shipboard electric networks

Описаны результаты исследований влияния показателей качества электроэнергии на токи однофазных замыканий в судовых электроустановках. Выявлены основные элементы бортовых электроустановок, влияющие на качество электроэнергии. Проанализировано формирование высших гармоник в токе однофазного замыкания. На физической модели электроустановки проведены исследования влияния нелинейной нагрузки на ток однофазного замыкания. Результаты экспериментов подтвердили установленные закономерности. Выявлено, что в установившемся режиме ток однофазного замыкания определяется не только величиной фазной емкости и напряжением сети, но и несинусоидальностью тока нагрузки. Экспериментально показано, что высшие гармоники, присутствующие в токе нагрузки, усиливаются в токе однофазного замыкания. При этом увеличение их амплитуд пропорционально номеру гармоники и ее амплитуде в токе нагрузки. Экспериментально установлено, что формирование высших гармоник в токе однофазного замыкания в результате эмиссии нелинейной нагрузкой приводит к увеличению его действующего значения. The paper represents the research results of the power quality indicators influence on the currents of single-phase ground faults in ship electrical installations. The main elements of on-board electrical installations that affect the quality of electricity are identified. The process of higher harmonics formation in the single-phase ground fault current is analyzed. Studies of the nonlinear load influence on the single-phase fault current are carried out on the physical model of the electrical installation. The experimental results confirmed the established patterns. For the steady-state mode it was discovered that the single-phase ground fault current is determined not only by the phase capacitance value and the mains voltage, but also by the non-sinusoidality of the load current. It has been shown experimentally that the higher harmonics of the load current are amplified in the single-phase ground fault current. In this case, the increase at their amplitudes is proportional to the harmonic number and its amplitude in the load current. It has been experimentally established that the formation of higher harmonics at a single-phase ground fault current as a result of emission by a nonlinear load leads to an increase in its effective value.

Taming the Load Current of Identical Cells in Matrix

We explore the load current [Formula: see text] for a rectangular array (matrix) of [Formula: see text] identical cells where [Formula: see text] strings (columns) of [Formula: see text] serial cells (rows) are arrayed in parallel. [Formula: see text] is equal to [Formula: see text] with the internal resistance of the cell and the load resistance exchanged. By treating a linear fractional function as a translated inversely-proportional function, we can easily capture the properties of [Formula: see text] and the relative magnitude of [Formula: see text] and [Formula: see text] via their ratio. The limiting behaviors of the load current are discussed beyond the ideal-cell and short-circuit limits. For the given total number of cells, we graphically verify the recent findings on the matrix of cells that produces the maximum load current. Finally, we analyze the possibility of a car starting with lemon cells or AA dry cells in matrix. This work would be useful in creating a high school or university curriculum that unifies identical cells in series, parallel, or matrix.