共查询到17条相似文献,搜索用时 218 毫秒
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以作为独立光伏发电系统中DC-DC变换器的基于增强型Ga N晶体管的高频LLC谐振变换器为研究对象,通过LTSPICE仿真和实验研究的方法,对增强型Ga N晶体管、高频平面变压器、不同输出二极管在LLC谐振变换器的应用现象进行理论分析、仿真与实验验证。研究结果表明:采用增强型Ga N晶体管及平面变压器的LLC谐振变换器可实现高频软开关,样机薄而小,可提高功率密度;增强型Ga N晶体管反向导通时,其源-漏极电压Vsd较大;200 k Hz开关频率下输出二极管结电容较小,易实现零电流开关,提高效率。 相似文献
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为解决单相高频链矩阵式逆变器在换流时变压器副边后级电路功率器件上存在的电压过冲问题,通过在变压器原边的前级H桥逆变电路中引入LC串联谐振槽的方式,提出一种串联谐振式高频链矩阵逆变器结构,并对此提出一种电流型解结耦单极性调制方法。在所提方案中,高频链变压器前级逆变电路采用脉宽脉位调制(sinusoidal pulse width and position modulation,SPWPM)以输出高频谐振电流,后级矩阵变换器应用电流型解结耦调制策略,通过与前级电路保持同步工作,构造前级输出电流的无中断的流通路径,以避免对变压器副边漏感电流的强制打断,可实现矩阵变换器的谐振软开关安全换流。在重点阐述串联谐振式高频链逆变器的工作原理并分析电流型解结耦单极性调制策略的具体工作模态的基础上,通过仿真和实验验证所提电路及其调制方法的可行性与有效性。 相似文献
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为减小双向变换器低压侧电流纹波,改善变换器硬开关现象,降低其闭环系统设计的复杂程度,提出一种谐振型混合调制的电流型高增益双向变换器。该变换器在低压侧全桥桥臂中点加入2个交错并联的Boost电感,在增加变换器增益的同时可减小变换器低压侧电流纹波,高压侧为倍压整流电路,进一步增加了变换器增益,同时利用变压器漏感与谐振电容谐振创造了高压侧开关管ZCS的条件。该变换器正反向均采用PWM+PFM混合调制控制,通过改变占空比调节输出电压,调节开关频率实现高压侧开关管的ZCS,采用该控制方案降低了变换器闭环系统设计的复杂程度,并可减小高压侧开关管的关断损耗。搭建一台600 W试验样机,进行正反向实验,验证所提方案的有效性。 相似文献
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常用来降低电子变压器主开关损耗的方法。目前是基于LLC谐振网络的软开关技术。其中谐振参数的选取是否合适直接影响到电子变压器输出性能的好坏。为此,该文引入布谷鸟搜索算法对谐振参数进行智能优化设计。该搜索算法能够对存在不可导点的目标函数进行优化,并且其特有的巢寄生行为和莱维飞行特性能够使得谐振参数避免陷入局部最优。其优化过程首先利用基波分析法对变换器的参数进行建模,然后分析和研究谐振电感、励磁电感与谐振网络直流增益、输入阻抗角以及原、副边电流、励磁电流的直接关系,从而得到参数优化的约束条件。在此基础上,利用布谷鸟搜索算法优化得到使电路损耗最小的谐振网络参数。最后,以半桥LLC谐振变换电路为例,通过实验验证了在宽输入电压下,全负载范围内,该优化设计方法比"FHA+仿真"法的效率提高了1%~2%,样机最高效率达97%,证明了论文所提优化方法的有效性。 相似文献
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为适应宽范围输入电压场合,该文结合变频控制(variable frequency control,VFC)和移相控制(phase shift control,PSC)这2种控制方式的特点,提出在输入高压时变换器进行移相控制,输入低压时进行变频控制的混合式控制方法。详细分析了在2种不同模式控制下全桥CLL谐振变换器的原理以及特性,并对变换器的谐振网络参数进行合理的设计。以500 W原理样机为例,对混合式控制全桥CLL谐振变换器进行实验验证。实验结果表明在混合控制策略下,全桥CLL谐振变换器能够实现原边开关管的零电压开通(zero voltage switching,ZVS)和副边整流二极管的零电流关断(zero-current switching,ZCS),并具有开关频率变化范围窄、效率高等特点。 相似文献
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In this paper, an interleaved soft-switched active-clamped L–L type current-fed half-bridge isolated dc–dc converter has been proposed. The L–L type active-clamped current-fed converter is able to maintain zero-voltage switching (ZVS) of all switches for the complete operating range of wide fuel cell stack voltage variation at full load down to light load conditions. Active-clamped circuit absorbs the turn-off voltage spike across the switches. Half-bridge topology maintains higher efficiency due to lower conduction losses. Soft-switching permits higher switching frequency operation, reducing the size, weight and cost of the magnetic components. Interleaving of the two isolated converters is done using parallel input series output approach and phase-shifted modulation is adopted. It reduces the input current ripple at the fuel cell input, which is required in a fuel cell system and also reduces the output voltage ripples. In addition, the size of the magnetic/passive components, current rating of the switches and voltage ratings of the rectifier diodes are reduced. 相似文献
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CLLC谐振变换器因其可实现软开关、功率密度高、调压范围大等优点受到广泛关注,但其传统的控制方法存在开关频率变化大、软开关实现范围窄的不足,导致CLLC变换器效率和功率密度的进一步提高受限。针对上述问题,提出一种CLLC变换器的新型调频-扩展移相控制方法,将控制分为两段并给出了分段的边界条件,通过移相控制缩短了开关频率变化范围,通过增加原边和副边桥的移相角增大了软开关范围。基于基波模型分析了变换器的增益模型和软开关临界条件,并基于MATLAB进行多种控制方法下的对比试验,验证了所提控制方法的正确性和有效性。 相似文献
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Multilevel inverter is an effective and practical solution for increasing power demand and reducing harmonics of AC waveforms. It is mainly employed in the distributed energy sources area because several batteries, fuel cell and solar cell can be connected through multilevel inverter to feed a load. This paper investigates the potentials of a single-phase Hybrid Cascaded Multilevel Inverter (HCMLI) fed from Proton Exchange Membrane Fuel Cell (PEMFC). A mathematical model of the PEMFC supplying HCMLI has been developed. This paper also presents the effect of a novel hybrid modulation on the device switching losses and harmonics of HCMLI. The proposed hybrid modulation technique combines the fundamental frequency switching scheme and Variable Frequency Inverted Sine Pulse Width Modulation (VFISPWM) technique. A comparison between the hybrid modulation strategy and the conventional Phase Disposition (PD) PWM method is also presented in terms of THD and switching losses. A suitable PID controller has been designed to control the output voltage of fuel cell based HCMLI, so that it can provide constant AC voltage with minimum THD up to the rated conditions. The inverter circuit topology and its control scheme are described in detail and their performance is verified based on simulation and experimental results. 相似文献
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This paper presents a pulse density modulation (PDM) controlled resonant converter for photo-voltaic (PV) system. Maximum power point of the PV generation system is tracked by deleting some control pulses of full bridge series resonant converter. Phase of the converter current is controlled by phase locked loop circuit and zero current switching is achieved for different irradiation conditions. Perturb and observe method is used for maximum power point tracker and designed system is experimentally tested by solar array simulator for 600 W PV power with 116 kHz PDM-MPPT controlled resonant converter. 相似文献