A circuit for balancing Li-ion battery cells is proposed. This circuit requires one small transformer and N + 3 bilateral switches to equalize the charging states of N serially connected battery ...cells. The transformer works as an energy carrier, and the switches select two unbalanced cells that require an energy transfer from one to the other cell. The circuit was tested for a 12-cell Li-ion battery under static, cyclic, and dynamic charging/discharging conditions. Under static condition, the power-transfer efficiency was measured as 80.4% at a balancing power of 0.78 W; two 4400-mA·h battery cells at a state of charge (SOC) = 70 and 80% were equalized after 78 min. The results of cyclic and dynamic charging/discharging conditions show that the circuit is appropriate for balancing the Li-ion battery cells for vehicles and energy storage systems.
A modularized design of an active charge equalizer and a charge equalization algorithm for a Li-ion battery pack are proposed in this paper. The equalizer consists of one module-balancing circuit and ...M cell-balancing circuits, where M is the number of modules in the battery pack. Each balancing circuit uses an inductor that is placed in a bridge of four bidirectional switches and works as an energy carrier, and uses a cell/module access network that enables energy transfer from one cell/module to another cell or module. The charge equalization between modules can be performed simultaneously with that between cells, so the proposed circuit can significantly reduce the time required to equalize the charges of all cells in the battery pack. The proposed circuit was tested under various charging/discharging conditions for a battery pack composed of four serially connected modules, with four serially connected cells per module. Experimental results show that the proposed circuit and algorithm comprise a good solution to balance a Li-ion battery pack.
In this work, a new active balancing circuit is proposed. This circuit consists of a cell-access network and an energy-transfer network. The cell-access network requires 2n + 6 switches, where n is ...the number of cells, and creates an energy-transfer path between unbalanced cells and the energy-transfer network. The energy-transfer network has double energy carriers and simultaneously implements cell-to-pack and pack-to-cell balancing operations without overlapping. As a result, a high power rate and fast balancing operation can be achieved by using two energy carriers in a single balancing circuit. The prototype of a proposed balancing circuit was built for six cells and then tested under various conditions; all cells in the state of charge (SOC) region of 70% to 80% were equalized after 93 min, and one charging/discharging period in the SOC region of 10% to 90% was increased by 8.58% compared to the non-balancing operation. These results show that the proposed circuit is a good way to balance charges among batteries in a battery pack.
This paper proposes a circuit structure of bidirectional dc-dc converter. This structure uses two switches, two capacitors, a 1:1 transformer, and a control circuit for pulse-frequency modulation. ...The windings of the transformer are connected in a series-aiding configuration to reduce current ripples and to increase power conversion efficiency <inline-formula><tex-math notation="LaTeX">\eta _{e}</tex-math></inline-formula>. The capacitors and the leakage inductance of the transformer provide soft-switching conditions. When the proposed converter was designed to operate at a switching frequency of 110-240 kHz, input/output voltages of 100-400 V, and output power <inline-formula><tex-math notation="LaTeX">P_{o}</tex-math></inline-formula> of 30-300 W, <inline-formula> <tex-math notation="LaTeX">\eta _{e}</tex-math></inline-formula> was ≥97% for <inline-formula> <tex-math notation="LaTeX">P_{o}\,\geq \,{\text{90}}\,{\text{W}}</tex-math></inline-formula> and 93.5% at <inline-formula><tex-math notation="LaTeX">P_{o}\,= \,{\text{30}}\,{\text{W}}</tex-math></inline-formula>. Experimental results show that the proposed converter is suitable for use in photovoltaic power conversion systems and energy storage systems.
This paper proposes a grid-connected single-stage micro-inverter with low cost, small size, and high efficiency to drive a 320 W class photovoltaic panel. This micro-inverter has a new and advanced ...topology that consists of an interleaved boost converter, a full-bridge converter, and a voltage doubler. Variable switching frequency and advanced burst control schemes were devised and implemented. A 320 W prototype micro-inverter was very compact and slim with 60-mm width, 310-mm length, and 30-mm height. In evaluations, the proposed micro-inverter achieved CEC weighted efficiency of 95.55%, MPPT efficiency >95% over the entire load range, and THD 2.65% at the rated power. The proposed micro-inverter is well suited for photovoltaic micro-inverter applications that require low cost, small size, high efficiency, and low noise.
This paper proposes a bidirectional dc–dc converter for residential micro-grid applications. The proposed converter can operate over an input voltage range that overlaps the output voltage range. ...This converter uses two snubber capacitors to reduce the switch turn-off losses, a dc-blocking capacitor to reduce the input/output filter size, and a 1:1 transformer to reduce core loss. The windings of the transformer are connected in parallel and in reverse-coupled configuration to suppress magnetic flux swing in the core. Zero-voltage turn-on of the switch is achieved by operating the converter in discontinuous conduction mode. The experimental converter was designed to operate at a switching frequency of 40–210 kHz, an input voltage of 48 V, an output voltage of 36–60 V, and an output power of 50–500 W. The power conversion efficiency for boost conversion to 60 V was ≥98.3% in the entire power range. The efficiency for buck conversion to 36 V was ≥98.4% in the entire power range. The output voltage ripple at full load was <3.59 Vp.p for boost conversion (60 V) and 1.35 Vp.p for buck conversion (36 V) with the reduced input/output filter. The experimental results indicate that the proposed converter is well-suited to smart-grid energy storage systems that require high efficiency, small size, and overlapping input and output voltage ranges.
A new circuit structure and control method for a high power interleaved dual-buck inverter are proposed. The proposed inverter consists of six switches, four diodes and two inductors, uses a ...dual-buck structure to eliminate zero-cross distortion, and operates in an interleaved mode to reduce the current stress of switch. To reduce the total harmonic distortion at low output power, the inverter is controlled using discontinuous-current-mode control combined with continuous-current-mode control. The experimental inverter had a power-conversion efficiency of 98.5% at output power = 1300 W and 98.3% at output power = 2 kW, when the inverter was operated at an input voltage of 400 VDC, output voltage of 220 VAC/60 Hz, and switching frequency of 20 kHz. The total harmonic distortion was < 0.66%, which demonstrates that the inverter is suitable for high-power dc-ac power conversion.
We propose a duty-ratio feed-forward controller for flyback power factor correction (PFC) converters operating in discontinuous conduction mode (DCM). For PFC applications, the power factor (PF) of ...the input current must be high under most load conditions. To improve PF of the flyback converter even under light load, we propose a compensation method for input capacitor current. The proposed controller significantly improves the displacement factor as well as the distortion factor, and therefore fly-back PFC converter can achieve the high power quality. Meanwhile, the output voltage of the PFC converter is well regulated. The derivation of the proposed method is presented and effectiveness of the proposed method is demonstrated in experiments with a 100-W rated power prototype.
본 연구는 고지방식이(HFD)를 제공한 비만동물모델에서 Momordica charanatia (MC)와 Withania somnifera (WS) 추출물의 혈청 콜레스테롤 및 내장지방 감소효과를 분석하였다. 유산균으로 발효한 MC와 WS 추출물의 조합(FMCWS) 및 비발효 추출물(MCWS)의 조합을 HFD로 유도된 비만마우스에 8주 동안 경구 ...투여하였다. 실험 기간 동안 체중, 식이섭취량, 총 콜레스테롤, 중성지방, HDL-콜레스테롤 수치를 분석하였다. 체중과 총 콜레스테롤 및 중성지방 수치는 정상대조(NC)군과 비교하여 HFD를 섭취한 HFD군에서 유의하게 증가했다. 그러나, 추출물의 투여로 인해 비만마우스의 체중증가가 감소되는 경향을 확인하였고 더불어 HDL-콜레스테롤의 증가와 함께 총 콜레스테롤 및 중성지방 수치를 유의적으로 감소시켰다. 복부지방 무게와 부고환 지방조직 내 지방세포의 크기는 NC군에 비해 HFD군에서 유의하게 증가하였다. 그러나, FMCWS와 MCWS를 각각 투여한 군은 HFD군에 비해 복부지방 무게와 부고환 지방세포의 크기가 유의하게 감소하였다. 또한, HFD군의 간 조직에서 관찰되는 거대 소포성 지방구의 침착이 이들 군에서는 현저하게 감소하였다. 이러한 결과는 MC와 WS 추출물의 조합이 체중 증가에 대한 감소 경향이 있을 뿐만 아니라 내장지방 및 혈청 지질 수준을 현저히 낮추는 데 강력한 시너지 효과가 있어 HFD 유발 비만마우스에서 항비만 활성을 향상시키는 효능이 있음을 시사한다.
We investigated the serum cholesterol and visceral fat lowering effects of Momordica charanatia (MC) and Withania somnifera (WS) extracts in high-fat diet (HFD)-fed mice. Combination of fermented MC and WS extracts (FMCWS) as well as that of non-fermented extracts (MCWS) were orally administered to HFD-induced obese mice along with the HFD supplementation for 8 weeks. During the experiment, body weight, food intake, and levels of total cholesterol, triglyceride and HDL-cholesterol were analyzed. Body weight and the levels of total cholesterol and triglycerides were significantly increased in the HFD-fed mice compared with the normal control (NC) group. However, supplementation of the extracts showed a tendency to reduce body weight gain and suppressed the levels of total cholesterol and triglyceride with the increment of HDL-cholesterol levels. Abdominal fat weight was significantly increased in the HFD group, and the size of adipocytes within the epididymal adipose tissue was markedly expanded compared with the NC group. However, in the FMCWS and MCWS groups, the abdominal fat weight was significantly reduced and the sizes of the adipocytes were noticeably diminished compared with those of the HFD-fed mice. Moreover, the deposition of giant vesicular fat cells observed in the liver tissue of the HFD group was prominently reduced in these groups. These results indicate that the combination of extracts from MC and WS tends to have potent synergic effects in reducing body weight gain as well as significantly lowering the visceral fat and the serum lipid levels, and thus improving anti-obesity efficacy in HFD-induced obese mice.
본 연구에서는 고지방식이(HFD)를 급식하여 제조한 비만마우스 모델을 사용하여 berberine (BBR)과 silibinin (SBN) 복합투여가 혈중 지질대사 및 항비만 개선 효능에 유의적인 시너지 효과가 있는지 조사하였다. HFD로 유도된 비만마우스를 8 주 동안 HFD의 지속적인 제공와 함께 BBR 및 SBN (BBR-SBN) 조합을 투여하였다. ...실험이 진행되는 동안 체중과 식이량을 측정하였고 혈중 총 콜레스테롤, 중성지방 및 HDL 콜레스테롤 수준을 분석하였다. HFD를 제공한 마우스는 정상 대조군(NC) 그룹에 비해 체중과 총 콜레스테롤 및 중성지방 수치가 급격히 증가했다. 그러나 이러한 비만마우스에 BBR-SBN조합을 투여 하였을 때 체중 증가가 현저하게 감소하였고 HDL 콜레스테롤 수치가 증가하였으며 총 콜레스테롤 및 중성지방 수치는 유의하게 억제되었다. HFD그룹의 복부지방 무게는 유의하게 증가했으며 부고환 지방조직 내의 지방세포의 크기가 NC 그룹에 비해 크게 확장된 것으로 나타났다. 그러나 BBR-SBN 그룹에서는 지방세포의 크기가 NC 그룹의 크기와 비슷했으며 복부지방 무게가 현저하게 감소하였다. 더불어, HFD 그룹에서 보이는 간 조직의 거대 소포성 지방구의 축적은 BBR-SBN 그룹에서 크게 감소되었다. 이러한 결과는 BBR-SBN 조합이 HFD 유발 비만마우스에서 체중 및 복부 지방 증가를 현저하게 감소시키는 경향이 있으며 혈청 내의 총 콜레스테롤 및 중성지방 수준을 낮추어 항비만 효능을 개선시킬 수 있는 가능성을 보여주는 것으로 앞으로 항비만 치료 및 개선제제로서의 잠재력을 가지고 있음을 시사한다.
In this study, we investigated whether the combined administration of berberine (BBR) and silibinin (SBN) was effective in improving hyperlipidemia and anti-obesity efficacy using a high-fat diet (HFD)-fed obese mouse model. HFD-induced obese mice were supplemented with the BBR and SBN combination (BBR-SBN) along with the HFD administration for 8 weeks. During the experiment, body weight, food intake, and levels of total cholesterol, triglyceride and high-density lipoprotein (HDL)-cholesterol were analyzed. Consumption of HFD in the mice caused rapid increases in body weight and the levels of total cholesterol and triglycerides compared to the normal control (NC) group. However, supplementation of BBR-SBN in these obese mice significantly reduced body weight gain and suppressed the levels of total cholesterol and triglyceride with the increment of HDL cholesterol level. In the HFD-fed group, abdominal fat weight was significantly increased and the adipocytes within the epididymal adipose tissue were found to have expanded sizes compared to the NC group. However, in the BBR-SBN group, the sizes of the adipocytes were comparable to those of the NC group and abdominal fat weight was significantly reduced. Moreover, the deposition of giant vesicular fat cells in liver tissues seen in the HFD-fed group was considerably reduced in the BBR-SBN group. These results suggest that the BBR-SBN combination tends to have synergic potential as an anti-obesity agent by significantly reducing body weight gain as well as lowering serum lipid levels and thus improving anti-obesity efficacy in HFD-induced obese mice.
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