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
Over the last few years, smart grids have become a topic of intensive research, development and deployment across the world. This is due to the fact that, through the smart grid, stable and reliable power systems can ...Over the last few years, smart grids have become a topic of intensive research, development and deployment across the world. This is due to the fact that, through the smart grid, stable and reliable power systems can be achieved. This paper presents a fuzzy logic control for dual active bridge series resonant converters for DC smart grid application. The DC smart grid consists of wind turbine and photovoltaic generators, controllable and DC loads, and power converters. The proposed control method has been applied to the controllable load＇s and the grid side＇s dual active bridge series resonant converters for attaining control of the power system. It has been used for management of controllable load＇s state of charge, DC feeder＇s voltage stability during the loads and power variations from wind energy and photovoltaic generation and power flow management between the grid side and the DC smart grid. The effectiveness of the proposed DC smart grid operation has been verified by simulation results obtained by using MATLAB and PLECS cards.展开更多
High efficiency and fast dynamic response are two main control objectives for dual active bridge(DAB)DC-DC converters. Traditional extended phase shift(EPS)control can significantly enhance the conversion efficiency o...High efficiency and fast dynamic response are two main control objectives for dual active bridge(DAB)DC-DC converters. Traditional extended phase shift(EPS)control can significantly enhance the conversion efficiency of DAB DC-DC converters by reducing current stress;however, it cannot fulfill fast dynamic response requirements. In this paper, a novel hybrid control scheme consisting of EPS control and direct power control(DPC),named as EPS-DPC, is proposed. EPS-DPC control has salient features in both efficiency and dynamic performance. In order to verify the outstanding performance of the proposed EPS-DPC scheme, an experimental comparison was carried out on a scale-down DAB DC-DC converter among several control strategies, including single phase shift control with traditional voltage-loop(SPS-TVL), EPS control with traditional voltage-loop(EPSVTL), and EPS-DPC. Experimental results have been high consistent with theoretical analysis, and verified these advantages of the proposed EPS-DPC scheme.展开更多
The dual active bridge(DAB) converters are widely used in the energy storage equipment and the distributed power systems. However, the existence of switching nonlinearity and control delay can cause serious stability ...The dual active bridge(DAB) converters are widely used in the energy storage equipment and the distributed power systems. However, the existence of switching nonlinearity and control delay can cause serious stability problem to the DAB converters. Thus, this paper,studies the stability of a digitally controlled DAB converter with an output voltage closed loop controller. Firstly, to accurately study the stability in a DAB converter, a discrete-time model established in a whole switching period is obtained. The model considers the output capacitor ESR,the digital control delay, and sample-and-hold process. By using this model, the stabilities of the DAB converter versus the proportional controller parameter and the output capacitor ESR are analyzed and the critical values are predicted accurately. Moreover, the stability boundary ofthe proportional controller parameter and the output capacitor ESR is also obtained. The result shows that the value of the output capacitor ESR can have a great effect on the stability region of the proportional controller parameter. Finally, the theoretical analyses are verified by the simulation and experimental results.展开更多
The three-phase dual active bridge(3 p-DAB)converter is widely considered in next-generation DC grid applications.As for traditional AC grids,the successful integration of power electronic converters in DC grids requi...The three-phase dual active bridge(3 p-DAB)converter is widely considered in next-generation DC grid applications.As for traditional AC grids,the successful integration of power electronic converters in DC grids requires accurate time-domain system-level studies.As demonstrated in the existing literature,the development and efficient implementation of large-signal models of 3 pDAB converters are not trivial.In this paper,a generalized average model is developed,which enables system-level simulation of DC grids with 3 p-DAB converters in electromagnetic transient type(EMT-type)programs.The proposed model is rigorously compared with alternative modeling techniques:ideal-model,switching-function and state-space averaging.It is concluded that the generalized average model provides an optimal solution when accuracy of transient response,reduction in computation time,and wideband response factors are considered.展开更多
双有源全桥(Dual Active Bridge,DAB)变换器在传统移相调制方式下,会产生较大的回流功率且动态特性较差。为解决上述问题,提出了一种基于扩展移相调制的输出电压模型预测控制方法。在回流功率产生机理分析基础上,通过建立DAB变换器输出...双有源全桥(Dual Active Bridge,DAB)变换器在传统移相调制方式下,会产生较大的回流功率且动态特性较差。为解决上述问题,提出了一种基于扩展移相调制的输出电压模型预测控制方法。在回流功率产生机理分析基础上,通过建立DAB变换器输出功率与回流功率的数学模型,采用状态空间平均法推导DAB变换器输出电压的模型预测方程,求取最佳移相比控制DAB,实现回流功率抑制。最后,搭建电路模型对分析结论进行验证,相较于传统单移相调制与扩展移相调制方式,仿真结果证实文中所提方法对DAB变换器回流功率有显著抑制作用,且能够有效改善其输出性能。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Over the last few years, smart grids have become a topic of intensive research, development and deployment across the world. This is due to the fact that, through the smart grid, stable and reliable power systems can be achieved. This paper presents a fuzzy logic control for dual active bridge series resonant converters for DC smart grid application. The DC smart grid consists of wind turbine and photovoltaic generators, controllable and DC loads, and power converters. The proposed control method has been applied to the controllable load＇s and the grid side＇s dual active bridge series resonant converters for attaining control of the power system. It has been used for management of controllable load＇s state of charge, DC feeder＇s voltage stability during the loads and power variations from wind energy and photovoltaic generation and power flow management between the grid side and the DC smart grid. The effectiveness of the proposed DC smart grid operation has been verified by simulation results obtained by using MATLAB and PLECS cards.
基金supported by the National Natural Science Foundation of China(No.51577160)
文摘High efficiency and fast dynamic response are two main control objectives for dual active bridge(DAB)DC-DC converters. Traditional extended phase shift(EPS)control can significantly enhance the conversion efficiency of DAB DC-DC converters by reducing current stress;however, it cannot fulfill fast dynamic response requirements. In this paper, a novel hybrid control scheme consisting of EPS control and direct power control(DPC),named as EPS-DPC, is proposed. EPS-DPC control has salient features in both efficiency and dynamic performance. In order to verify the outstanding performance of the proposed EPS-DPC scheme, an experimental comparison was carried out on a scale-down DAB DC-DC converter among several control strategies, including single phase shift control with traditional voltage-loop(SPS-TVL), EPS control with traditional voltage-loop(EPSVTL), and EPS-DPC. Experimental results have been high consistent with theoretical analysis, and verified these advantages of the proposed EPS-DPC scheme.
基金supported by National Natural Science Foundation of China(NSFC)(No.51207126)
文摘The dual active bridge(DAB) converters are widely used in the energy storage equipment and the distributed power systems. However, the existence of switching nonlinearity and control delay can cause serious stability problem to the DAB converters. Thus, this paper,studies the stability of a digitally controlled DAB converter with an output voltage closed loop controller. Firstly, to accurately study the stability in a DAB converter, a discrete-time model established in a whole switching period is obtained. The model considers the output capacitor ESR,the digital control delay, and sample-and-hold process. By using this model, the stabilities of the DAB converter versus the proportional controller parameter and the output capacitor ESR are analyzed and the critical values are predicted accurately. Moreover, the stability boundary ofthe proportional controller parameter and the output capacitor ESR is also obtained. The result shows that the value of the output capacitor ESR can have a great effect on the stability region of the proportional controller parameter. Finally, the theoretical analyses are verified by the simulation and experimental results.
文摘The three-phase dual active bridge(3 p-DAB)converter is widely considered in next-generation DC grid applications.As for traditional AC grids,the successful integration of power electronic converters in DC grids requires accurate time-domain system-level studies.As demonstrated in the existing literature,the development and efficient implementation of large-signal models of 3 pDAB converters are not trivial.In this paper,a generalized average model is developed,which enables system-level simulation of DC grids with 3 p-DAB converters in electromagnetic transient type(EMT-type)programs.The proposed model is rigorously compared with alternative modeling techniques:ideal-model,switching-function and state-space averaging.It is concluded that the generalized average model provides an optimal solution when accuracy of transient response,reduction in computation time,and wideband response factors are considered.
文摘双有源全桥(Dual Active Bridge,DAB)变换器在传统移相调制方式下,会产生较大的回流功率且动态特性较差。为解决上述问题,提出了一种基于扩展移相调制的输出电压模型预测控制方法。在回流功率产生机理分析基础上,通过建立DAB变换器输出功率与回流功率的数学模型,采用状态空间平均法推导DAB变换器输出电压的模型预测方程,求取最佳移相比控制DAB,实现回流功率抑制。最后,搭建电路模型对分析结论进行验证,相较于传统单移相调制与扩展移相调制方式,仿真结果证实文中所提方法对DAB变换器回流功率有显著抑制作用,且能够有效改善其输出性能。
