音频类设备是煤矿井下设备的重要组成部分,例如广播音箱、电话、工作面通讯装置、声光信号通讯器、手机等很多类的设备和系统。目前我们人的耳朵能够听到频率20 Hz^15 k Hz范围内的音频信号,而人嘴巴发出的语音信号约分布在300~3400Hz...音频类设备是煤矿井下设备的重要组成部分,例如广播音箱、电话、工作面通讯装置、声光信号通讯器、手机等很多类的设备和系统。目前我们人的耳朵能够听到频率20 Hz^15 k Hz范围内的音频信号,而人嘴巴发出的语音信号约分布在300~3400Hz。因此300~3400Hz的语音信号可用来确定语音内容或判断说话者的身份;音频可经过音频设备模拟化,成为模拟音频,也可经音频设备数字化成为数字音频。根据音频在传输和转换的过程中会出现失真,定义了音频失真的概念,解释了失真度的含义,并分析了失真度测量的2种测试方法。并通过介绍失真度仪和音频分析仪的使用,明确了实际检测过程中的THD测量和THD+N测量的方法。展开更多
A comprehensive predictive strategy was proposed for the neutral-point balancing control of back-to-back three-level converters. The phase currents at both sides and the DC-link capacitor voltages were measured for th...A comprehensive predictive strategy was proposed for the neutral-point balancing control of back-to-back three-level converters. The phase currents at both sides and the DC-link capacitor voltages were measured for the prediction of the neutral-point current. A quality function was found to balance the neutral-point, and a metabolic on-times distribution factor was used as a predicator to minimize the quality function at each switching state. Simulation results show that the proposed method produces smaller ripples in tested signals compared with the established one, namely, 9.15% less in a total harmonic distortion(THD) of line-to-line voltage, 1.08% less in the THD of phase current, and 0.9 V less in the ripple of the neutral-point voltage. The obtained experimental results show that the main harmonics of the line-to-line voltage and the phase current in the proposed method are improved by 10 d B and 6 d B, respectively, and the ripple of neutral-point voltage is halved compared to the established one.展开更多
文摘音频类设备是煤矿井下设备的重要组成部分,例如广播音箱、电话、工作面通讯装置、声光信号通讯器、手机等很多类的设备和系统。目前我们人的耳朵能够听到频率20 Hz^15 k Hz范围内的音频信号,而人嘴巴发出的语音信号约分布在300~3400Hz。因此300~3400Hz的语音信号可用来确定语音内容或判断说话者的身份;音频可经过音频设备模拟化,成为模拟音频,也可经音频设备数字化成为数字音频。根据音频在传输和转换的过程中会出现失真,定义了音频失真的概念,解释了失真度的含义,并分析了失真度测量的2种测试方法。并通过介绍失真度仪和音频分析仪的使用,明确了实际检测过程中的THD测量和THD+N测量的方法。
基金Project(61074018)supported by the National Natural Science Foundation of ChinaProject(2012kfjj06)supported by Hunan Province Key Laboratory of Smart Grids Operation and Control(Changsha University of Science and Technology),China
文摘A comprehensive predictive strategy was proposed for the neutral-point balancing control of back-to-back three-level converters. The phase currents at both sides and the DC-link capacitor voltages were measured for the prediction of the neutral-point current. A quality function was found to balance the neutral-point, and a metabolic on-times distribution factor was used as a predicator to minimize the quality function at each switching state. Simulation results show that the proposed method produces smaller ripples in tested signals compared with the established one, namely, 9.15% less in a total harmonic distortion(THD) of line-to-line voltage, 1.08% less in the THD of phase current, and 0.9 V less in the ripple of the neutral-point voltage. The obtained experimental results show that the main harmonics of the line-to-line voltage and the phase current in the proposed method are improved by 10 d B and 6 d B, respectively, and the ripple of neutral-point voltage is halved compared to the established one.
