In this paper, on the basis of the phase shifted controlled zero voltage switch (ZVS) full bridge converter with pulse width modulation (PWM), a novel zero voltage and zero current switch (ZVZCS) PWM converter u...In this paper, on the basis of the phase shifted controlled zero voltage switch (ZVS) full bridge converter with pulse width modulation (PWM), a novel zero voltage and zero current switch (ZVZCS) PWM converter using a simple auxiliary circuit was designed. The ZVZCS soft switch is achieved by the resonance among the resisting electromagnetic deflection capacitor, the capacitor of the simple auxiliary network and the leakage inductor of transformer. There are no dissipation devices of the saturation inductor and the auxiliary switch in the converter, meantime the capacitor of the auxiliary circuit is also used to clamp the voltage of the rectifier, and there is no additional clamped circuit. There is no big circulating current in the converter, all the active and passive devices work on the condition of the low current and voltage stress, and the proposed converter has wide load range and small duty loss.展开更多
传统双向E型无线电能传输(wireless power transfer,WPT)拓扑易进入硬开关状态,导致电能传输效率低。针对此,该文提出无线电能传输系统的改进E^(#)型拓扑及其移相控制策略。首先,构建软开关状态负载范围更宽的双向E^(#)型WPT电路拓扑数...传统双向E型无线电能传输(wireless power transfer,WPT)拓扑易进入硬开关状态,导致电能传输效率低。针对此,该文提出无线电能传输系统的改进E^(#)型拓扑及其移相控制策略。首先,构建软开关状态负载范围更宽的双向E^(#)型WPT电路拓扑数学模型,分析并提取电路实现软开关工作状态的关键变量与约束条件,理论上证明所提拓扑的有效性。然后,推导电路中线圈互感和负载阻抗等参数的解析关系式,并基于此提出可保证系统在负载时始终处于最佳工作状态的移相控制策略。该策略通过控制开关管的门极驱动信号相位,使谐振元件内部储存的能量提前或者滞后释放,从而将开关管修正回软开关状态。最后,通过仿真和实验验证所提双向E^(#)型WPT系统的有效性。实验结果表明,所提方法可保证在5~30Ω的负载范围内电路工作在软开关状态,该范围内的电能传输效率峰值达84.3%。展开更多
近年来,零样本工业过程故障诊断方法逐渐受到关注.针对传统嵌入模型在零样本故障诊断中表现不佳的问题,提出一种基于语义增强型深度自编码器(semantic-enhanced deep autoencoder, SEDAE)的零样本故障诊断算法.首先,给出一种基于语义属...近年来,零样本工业过程故障诊断方法逐渐受到关注.针对传统嵌入模型在零样本故障诊断中表现不佳的问题,提出一种基于语义增强型深度自编码器(semantic-enhanced deep autoencoder, SEDAE)的零样本故障诊断算法.首先,给出一种基于语义属性空间三元组损失约束的投影域偏移消除方法,提升模型知识迁移的能力.然后,将三元组损失函数约束引入深度自编码器,自动提取已见类别语义特征,实现了已见类别语义知识与先验语义信息之间的最优映射.在此基础上,在语义空间使用最近邻方法确定新样本所属的类别.田纳西伊斯曼过程(Tennessee-Eastman process, TEP)仿真结果表明,所提零样本故障诊断方法准确率相较传统方法提升7.11%,在广义零样本故障诊断中也取得满意的结果.展开更多
文摘In this paper, on the basis of the phase shifted controlled zero voltage switch (ZVS) full bridge converter with pulse width modulation (PWM), a novel zero voltage and zero current switch (ZVZCS) PWM converter using a simple auxiliary circuit was designed. The ZVZCS soft switch is achieved by the resonance among the resisting electromagnetic deflection capacitor, the capacitor of the simple auxiliary network and the leakage inductor of transformer. There are no dissipation devices of the saturation inductor and the auxiliary switch in the converter, meantime the capacitor of the auxiliary circuit is also used to clamp the voltage of the rectifier, and there is no additional clamped circuit. There is no big circulating current in the converter, all the active and passive devices work on the condition of the low current and voltage stress, and the proposed converter has wide load range and small duty loss.
文摘传统双向E型无线电能传输(wireless power transfer,WPT)拓扑易进入硬开关状态,导致电能传输效率低。针对此,该文提出无线电能传输系统的改进E^(#)型拓扑及其移相控制策略。首先,构建软开关状态负载范围更宽的双向E^(#)型WPT电路拓扑数学模型,分析并提取电路实现软开关工作状态的关键变量与约束条件,理论上证明所提拓扑的有效性。然后,推导电路中线圈互感和负载阻抗等参数的解析关系式,并基于此提出可保证系统在负载时始终处于最佳工作状态的移相控制策略。该策略通过控制开关管的门极驱动信号相位,使谐振元件内部储存的能量提前或者滞后释放,从而将开关管修正回软开关状态。最后,通过仿真和实验验证所提双向E^(#)型WPT系统的有效性。实验结果表明,所提方法可保证在5~30Ω的负载范围内电路工作在软开关状态,该范围内的电能传输效率峰值达84.3%。
文摘偏航角零点漂移严重影响风电机组性能,将之消除的前提是对其进行可靠且快速的检测。基于风能捕获机理,该文提出一种运用机器学习算法的偏航角零点漂移诊断方法。首先,采用孤立森林(isolated forest,IF)异常值检测算法对数据进行预处理;其次,建立非参数模型稀疏高斯过程回归(sparse Gaussian process regression,SGPR)估计偏航角零点漂移;最后,利用多个风电场的风电机组实际运行数据对所提方法进行验证,并分析不同诊断模型对数据量的依赖性。结果表明:IF+SGPR方法准确性高,所需数据量少,能够快速诊断偏航角零点漂移;该诊断方法能够应用于各种电场不同型号的风电机组,普适性较高。
