In this paper, the zero voltage switching (ZVS) region of a dual active bridge (DAB) converter with wide band-gap (WBG) power semiconductor device is analyzed. The ZVS region of a DAB converter varies depending on out...In this paper, the zero voltage switching (ZVS) region of a dual active bridge (DAB) converter with wide band-gap (WBG) power semiconductor device is analyzed. The ZVS region of a DAB converter varies depending on output power and voltage ratio. The DAB converters operate with hard switching at light loads, it is difficult to achieve high efficiency. Fortunately, WBG power semiconductor devices have excellent hard switching characteristics and can increase efficiency compared to silicon (Si) devices. In particular, WBG devices can achieve ZVS at low load currents due to their low parasitic output capacitance (C<sub>o,tr</sub>) characteristics. Therefore, in this paper, the ZVS operating resion is analyzed based on the characteristics of Si, silicon carbide (SiC) and gallium nitride (GaN). Power semiconductor devices. WBG devices with low C<sub>o,tr</sub> operate at ZVS at lower load currents compared to Si devices. To verify this, experiments are conducted and the results are analyzed using a 3 kW DAB converter. For Si devices, ZVS is achieved above 1.4 kW. For WBG devices, ZVS is achieved at 700 W. Due to the ZVS conditions depending on the switching device, the DAB converter using Si devices achieves a power conversion efficiency of 91% at 1.1 kW output. On the other hand, in the case of WBG devices, power conversion efficiency of more than 98% is achieved under 11 kW conditions. In conclusion, it is confirmed that the WBG device operates in ZVS at a lower load compared to the Si device, which is advantageous in increasing light load efficiency.展开更多
This document addresses an exhaustive standalone Photovoltaic (PV) energy harvesting system considering two crucial issues: system efficiency and cost effectiveness. It contributes a compact resolution with a combined...This document addresses an exhaustive standalone Photovoltaic (PV) energy harvesting system considering two crucial issues: system efficiency and cost effectiveness. It contributes a compact resolution with a combined feature of Dual Mode-Multiple Output (DMMO) associated with input ripple reduction technique. Control strategy incorporates with aspect of Maximum Power Point Tracking (MPPT) and output voltage levels regulation. A theoretical analysis is conducted to evaluate the effect of ripple current on PV power. Proposed dual mode converter achieves efficiency of 98.36% and 97.76% respectively for mode-1 and mode-2 operation. However, simulation is performed applying MATLAB/SIMULINK tools to analyze the feasibility of the recommended system.展开更多
This paper proposes a triple output converter with buck, boost and inverted outputs and controlled through duty cycle estimation. In the existing converter, to generate the negative output, the power flows from load t...This paper proposes a triple output converter with buck, boost and inverted outputs and controlled through duty cycle estimation. In the existing converter, to generate the negative output, the power flows from load to the supply (from the boost output to the supply) during a part of the cycle, which increases cycle time and losses, and reduces the power level. To overcome this, a modified converter with a main and an auxiliary inductance and with reduced number of switches is proposed. The converter can operate in continuous and discontinuous conduction modes and the outputs can be independently controlled. An analysis of the converter is done for both modes. A simplified control of the converter through duty cycle estimation is suggested to regulate the outputs, which does not have the constraint that the current ripple has to be small. The control works both in the continuous and discontinuous modes. The simulation results closely match with the analysis. A prototype of the converter is constructed with a Spartan FPGA system and results have been presented.展开更多
输入串联输出并联型(input-series output-parallel,ISOP)直流变换器广泛应用于能源互联网中的直流电网场景,其关键问题在于解决系统模块间输入电压不均衡。为此,结合谐振型和移相型双有源桥(dual active bridge,DAB)变换器,提出一种具...输入串联输出并联型(input-series output-parallel,ISOP)直流变换器广泛应用于能源互联网中的直流电网场景,其关键问题在于解决系统模块间输入电压不均衡。为此,结合谐振型和移相型双有源桥(dual active bridge,DAB)变换器,提出一种具备自适应均压能力的混合型模块化ISOP型直流变换器,系统同时具备谐振型DAB的高效率和移相型DAB的灵活控制能力。通过在DAB源端的滞后桥臂中点增设无源的LC谐振支路,该谐振支路与相邻子模块的2个半桥模块共同构成非隔离型双有源半桥,以此来实现系统输入电压的自适应均衡。此外,提出一种低电压穿越(low voltage ride-through,LVRT)方法,在DAB前端连接电压调整模块,模块内部的高频变压器的副边串联电感,当系统输入输出侧发生电压跌落时具备故障穿越的能力,提高系统的暂态可控性。最后,在MATLAB/SIMULINK环境下搭建模型进行验证,可以证明系统的自适应均压性能及故障穿越方法的有效性。展开更多
在两级式逆变器中,后级逆变器在带有单相或三相不平衡负载时会产生二倍频的瞬时功率波动,此二倍频波动会耦合进入前级直流变换器,造成前级双有源串联谐振变换器(dual active bridge series resonant converter,DBSRC)的交流谐振电流幅...在两级式逆变器中,后级逆变器在带有单相或三相不平衡负载时会产生二倍频的瞬时功率波动,此二倍频波动会耦合进入前级直流变换器,造成前级双有源串联谐振变换器(dual active bridge series resonant converter,DBSRC)的交流谐振电流幅值出现较大的二倍频波动。考虑到DBSRC高阶模型较为复杂,提出简化的降阶一阶小信号模型。基于此简化模型,通过在电压闭环回路中串入二倍频陷波器,大范围地增加二倍频处的闭环输出阻抗,从而实现抑制前级的DBSRC的谐振电流波动。进一步,提出保证两级式逆变系统稳定的二倍频波动抑制的控制参数设计方法。最后,通过仿真和实验验证了所提出的简化降阶模型和控制系统参数设计的有效性和可行性。展开更多
输入串联输出并联(inputseriesoutputparallel,ISOP)双有源桥(dualactivebridge,DAB)变换器的输入均压(input voltage sharing,IVS)主动控制策略存在控制系统复杂和传感器数量较多的问题。相反地,无源调控方法的控制系统简单,因而具有...输入串联输出并联(inputseriesoutputparallel,ISOP)双有源桥(dualactivebridge,DAB)变换器的输入均压(input voltage sharing,IVS)主动控制策略存在控制系统复杂和传感器数量较多的问题。相反地,无源调控方法的控制系统简单,因而具有明显的优势。基于无源均压思想,提出一种适用于共占空比控制的基于耦合电容的ISOP-DAB变换器的输入电压自平衡拓扑结构,通过耦合电容使得子模块的高频链环节产生电气耦合,从而实现子模块输入电压的均衡。进一步,给出含有耦合电容的ISOP-DAB变换器的简化等效电路,并进行理论分析与推导,得到子模块输入母线电压偏差及耦合电容电流与变换器硬件参数的关系。理论计算表明该拓扑在子模块参数存在较大的偏差时仍然具有较好的IVS能力。最后,仿真和实验结果验证该拓扑的可行性和有效性。展开更多
文摘In this paper, the zero voltage switching (ZVS) region of a dual active bridge (DAB) converter with wide band-gap (WBG) power semiconductor device is analyzed. The ZVS region of a DAB converter varies depending on output power and voltage ratio. The DAB converters operate with hard switching at light loads, it is difficult to achieve high efficiency. Fortunately, WBG power semiconductor devices have excellent hard switching characteristics and can increase efficiency compared to silicon (Si) devices. In particular, WBG devices can achieve ZVS at low load currents due to their low parasitic output capacitance (C<sub>o,tr</sub>) characteristics. Therefore, in this paper, the ZVS operating resion is analyzed based on the characteristics of Si, silicon carbide (SiC) and gallium nitride (GaN). Power semiconductor devices. WBG devices with low C<sub>o,tr</sub> operate at ZVS at lower load currents compared to Si devices. To verify this, experiments are conducted and the results are analyzed using a 3 kW DAB converter. For Si devices, ZVS is achieved above 1.4 kW. For WBG devices, ZVS is achieved at 700 W. Due to the ZVS conditions depending on the switching device, the DAB converter using Si devices achieves a power conversion efficiency of 91% at 1.1 kW output. On the other hand, in the case of WBG devices, power conversion efficiency of more than 98% is achieved under 11 kW conditions. In conclusion, it is confirmed that the WBG device operates in ZVS at a lower load compared to the Si device, which is advantageous in increasing light load efficiency.
文摘This document addresses an exhaustive standalone Photovoltaic (PV) energy harvesting system considering two crucial issues: system efficiency and cost effectiveness. It contributes a compact resolution with a combined feature of Dual Mode-Multiple Output (DMMO) associated with input ripple reduction technique. Control strategy incorporates with aspect of Maximum Power Point Tracking (MPPT) and output voltage levels regulation. A theoretical analysis is conducted to evaluate the effect of ripple current on PV power. Proposed dual mode converter achieves efficiency of 98.36% and 97.76% respectively for mode-1 and mode-2 operation. However, simulation is performed applying MATLAB/SIMULINK tools to analyze the feasibility of the recommended system.
文摘This paper proposes a triple output converter with buck, boost and inverted outputs and controlled through duty cycle estimation. In the existing converter, to generate the negative output, the power flows from load to the supply (from the boost output to the supply) during a part of the cycle, which increases cycle time and losses, and reduces the power level. To overcome this, a modified converter with a main and an auxiliary inductance and with reduced number of switches is proposed. The converter can operate in continuous and discontinuous conduction modes and the outputs can be independently controlled. An analysis of the converter is done for both modes. A simplified control of the converter through duty cycle estimation is suggested to regulate the outputs, which does not have the constraint that the current ripple has to be small. The control works both in the continuous and discontinuous modes. The simulation results closely match with the analysis. A prototype of the converter is constructed with a Spartan FPGA system and results have been presented.
文摘输入串联输出并联型(input-series output-parallel,ISOP)直流变换器广泛应用于能源互联网中的直流电网场景,其关键问题在于解决系统模块间输入电压不均衡。为此,结合谐振型和移相型双有源桥(dual active bridge,DAB)变换器,提出一种具备自适应均压能力的混合型模块化ISOP型直流变换器,系统同时具备谐振型DAB的高效率和移相型DAB的灵活控制能力。通过在DAB源端的滞后桥臂中点增设无源的LC谐振支路,该谐振支路与相邻子模块的2个半桥模块共同构成非隔离型双有源半桥,以此来实现系统输入电压的自适应均衡。此外,提出一种低电压穿越(low voltage ride-through,LVRT)方法,在DAB前端连接电压调整模块,模块内部的高频变压器的副边串联电感,当系统输入输出侧发生电压跌落时具备故障穿越的能力,提高系统的暂态可控性。最后,在MATLAB/SIMULINK环境下搭建模型进行验证,可以证明系统的自适应均压性能及故障穿越方法的有效性。
文摘在两级式逆变器中,后级逆变器在带有单相或三相不平衡负载时会产生二倍频的瞬时功率波动,此二倍频波动会耦合进入前级直流变换器,造成前级双有源串联谐振变换器(dual active bridge series resonant converter,DBSRC)的交流谐振电流幅值出现较大的二倍频波动。考虑到DBSRC高阶模型较为复杂,提出简化的降阶一阶小信号模型。基于此简化模型,通过在电压闭环回路中串入二倍频陷波器,大范围地增加二倍频处的闭环输出阻抗,从而实现抑制前级的DBSRC的谐振电流波动。进一步,提出保证两级式逆变系统稳定的二倍频波动抑制的控制参数设计方法。最后,通过仿真和实验验证了所提出的简化降阶模型和控制系统参数设计的有效性和可行性。
文摘输入串联输出并联(inputseriesoutputparallel,ISOP)双有源桥(dualactivebridge,DAB)变换器的输入均压(input voltage sharing,IVS)主动控制策略存在控制系统复杂和传感器数量较多的问题。相反地,无源调控方法的控制系统简单,因而具有明显的优势。基于无源均压思想,提出一种适用于共占空比控制的基于耦合电容的ISOP-DAB变换器的输入电压自平衡拓扑结构,通过耦合电容使得子模块的高频链环节产生电气耦合,从而实现子模块输入电压的均衡。进一步,给出含有耦合电容的ISOP-DAB变换器的简化等效电路,并进行理论分析与推导,得到子模块输入母线电压偏差及耦合电容电流与变换器硬件参数的关系。理论计算表明该拓扑在子模块参数存在较大的偏差时仍然具有较好的IVS能力。最后,仿真和实验结果验证该拓扑的可行性和有效性。
