汽车雨刮器电机辐射骚扰抑制

某型雨刮器电机没有通过GB18655-2002规定的零部件宽带辐射骚扰测试。针对其实际测试结果进行了分析,并确定通过加装参数合适的滤波器进行电源线滤波。整改后,雨刮器电机的相关测试结果符合标准要求。     

船舶航行辐射噪声信号仿真方法研究

船舶航行辐射噪声是被动声纳探测、声纳目标识别、听音判型等工作的重要信息源,其信号仿真是解决上述研究工作中噪声样本类型少或数量不足的有效方法,前提是所仿真信号必须满足逼真度要求。提出了一种基于实测信号重构的船舶航行辐射噪声信号仿真方法。通过谱估计提取信号的连续谱、线谱、调制谱特征,根据谱估计数据合成满足信号谱特征要求的船舶航行辐射噪声,并通过听觉感受调整调制谱参数。仿真结果显示所合成船舶航行辐射噪声信号能够从谱估计和听觉感受两方面逼近实测辐射噪声信号。      

船舶航行辐射噪声的多普勒效应仿真

通过分析、比较已有水声信号多普勒频移仿真方法，针对船舶航行辐射噪声提出一种能够适应声源和接收者相对径向速度变化的、计算效率较高的水下宽带噪声信号多普勒效应仿真方法。仿真实验结果显示，该方法使船舶航行辐射噪声信号频域各分量的频率随着相对径向速度的变化呈现出不同的多普勒频移量，使得船舶航行辐射噪声信号的仿真达到了更高的逼真度。     

通讯设备中的辐射噪声及抑制措施

以通讯设备为例，叙述了辐射噪声产生的机理，抑制这类噪声的基本方法，并根据现有抑制噪声元件的特性，在通讯设备中的合理选用等技术。     

水中目标辐射噪声模拟技术研究

水中目标辐射噪声主要包括平滑连续谱和线谱两个部分,对平滑连续谱建立了功率谱数学模型.可以按照需求确定模型参数,通过Levinson算法递推出AR模型参数.对线谱的主要来源进行了分析.推导了线谱的简要模型,并考虑了多普勒效应.给出了水中目标噪声的简要仿真模型,并提出了一种基于PCI总线的实时噪声模拟硬件设计,该模拟硬件利用中断工作方式实现实时、不间断的噪声模拟输出,性能良好.     

船舶实测辐射噪声信号的调制谱重构仿真

提出一种船舶实测辐射噪声信号的调制谱重构仿真方法.对实测信号进行时域波形和调制谱分析,提取螺旋桨旋转周期、叶片数、脉冲宽度、调制深度参数;通过仿真生成调制脉冲幅度参数与调制谱谐波谱线之间关系的对照表,查表确定各螺旋桨叶片的调制脉冲幅度参数;基于上述参数实现船舶实测辐射噪声信号的调制谱重构.仿真结果表明,该重构方法能够较好地保持调制谱第一组特征谐波谱线的频率、谱级相对大小排序等重要信号特征.     

基于SeeSV噪声定位技术的电机噪声测试

针对驱动电机某一运转工况的噪声声压级与电机噪声频率的测试问题,提出了一种运用声学照相机SeeSV与传声器相结合,并同时检测电机振动信号的测试方法。通过选取SeeSV的不同频段对噪声源进行定位识别,分离出驱动电机的噪声频段,运用传声器测定电机的噪声强度,并用振动信号对声压信号进行验证。测试结果表明,用SeeSV和传声器相结合的方法,可在复杂噪声中识别出驱动电机的噪声频率为2 66625 Hz,声压级为607 dB,对工程噪声的评价具有实践意义。     

汽车暖风电机电磁辐射发射抑制

针对某配套厂家提供的暖风电机辐射发射测试结果不理想的问题,分析了其骚扰产生的机理,提出了抑制辐射发射的方法,即在原有电路基础上增加不同数值的X、Y电容,并对三种抑制方法进行了对比试验.结果表明,当盖沿增加导电泡棉,X电容为0.1 μF,Y电容为0.1 μF时,暖风电机辐射发射抑制的效果显著.     

用于可变速电机驱动设计的HVIC技术

可变速电机驱动可以提高机器设备的能源效率,但为了降低成本、提高市场响应速度和提高效率,还要在几个方面对可变速驱动设计进行改进.其中包括对IGBT很关键的线性电流反馈和过流保护特性,这两个功能传统上都是通过采用体积大、昂贵和难以组装的元器件来实现的.     

基于舰船辐射噪声的舰船目标定位技术

通过声传感器阵列可实现对声源的自适应检测定位及跟踪,这使得它在目标探测、故障诊断等诸多领域有着广泛的应用。在复杂环境中,常规的相关方法对于声源的定位往往难以得到准确的定位结果。针对常规时差测向定位抗干扰性能差和易受噪声影响,特别是噪声存在显著的尖峰时更不能得到满意结果的问题,本文提出基于盲分离的定位算法改进其性能。通过仿真实验,可以看到本文提出的定位方法能够取得更稳定、准确的结果。     

Robust DSP-based efficiency optimization of a variable speed induction motor drive

This paper proposes a practical digital-signal-processor (DSP)-based algorithm for the online efficiency optimization of induction motor drives. The algorithm combines good features of the search control and loss-model-based control, while simultaneously eliminating their major drawbacks. It ensures very fast convergence without the need for any a priori knowledge of the motor loss-related parameters. The minimum loss operating point is decided from a functional approximation of the motor and the power converter losses, in the form of a suitably defined loss function. The loss function parameters are obtained online from input power measurement and a dedicated identification routine acting in conjunction with the common drive control functions. Proposed online identification of the loss function parameters relies upon the signals and states readily available within the drive controller memory and does not involve the user entry nor the initialization procedure. The proposed controller is coded into a conventional low-cost 16-bit DSP and verified on a 2.2-kW induction motor drive prototype.     

A variable speed light chopper using a feedback controlled DC motor

A variable speed mechanical light chopper having a chopping frequency range from 10 to 2000 Hz using two chopping blades is described. A small DC motor whose speed can be varied ten fold was used and its speed was maintained constant by feedback control. The chopper has better than 0.l per cent stability and negligible temperature drift. The circuit is simple, inexpensive, and reliable.     

Novel soft-switching inverter for brushless DC motor variable speed drive system

Brushless DC motor has been widely used in industrial applications because of its low inertia, fast response, high power density, high reliability and maintenance-free. It is usually supplied by a hard-switching PWM inverter, which normally has low efficiency since the power losses across the switching devices are high. In order to reduce the losses, many soft switching inverters have been designed. Unfortunately, there are many drawbacks, such as high device voltage stress, large DC link voltage ripple, complex control scheme and so on. This paper introduces a novel soft-switching inverter which generates notches of the DC bus voltage becomes to zero during chopping switches commutation to guarantee all switches working in zero voltage state. The result of this investigation will be very useful for industrial applications.     

基于神经滑模变自抗扰控制的感应电机变频调速系统设计

基于强化感应电机变频调速系统的调速质量及响应速度的考量,文章设计出建立在神经滑模变自抗扰控制的感应电机变频调速系统。应用ADRC控制,在基础上提升了调速系统控制品质与控制精准性能。综合神经逆控制思想,创建起神经滑模变自抗扰控制器,减少系统的抖振现象,实现对感应电机调速系统转速、转矩、磁链等参数的最优化控制。     

AM noise of millimeter-wave Gunn oscillators

AM noise of a waveguide cavity Gunn oscillator operating around 33.0 GHz has been measured for frequency off carrier extending from 10 kHz to 1.5 MHz. The measurements indicate that AM noise, (N/C) AM, DSB is typically -165 dB/Hz, at frequencies sufficiently away from the carrier where contribution due to 1/f noise becomes small.     

基于模糊贴近度的舰船辐射噪声分类

误差反传神经网络在被动声呐目标分类中得到了广泛的应用,但该算法在搜索过程中容易陷入局部最小值,同时使用赢者独活的识别决策策略,导致识别率的下降。针对BP网络的弱点,提出了基于模糊非对称贴近度的舰船辐射噪声分类方法,该方法能在对BP网络不作大改动的前提下,解决神经网络陷入局部最小值的问题和使用赢者独活决策策略导致误识的弱点。实验结果证明了该方法是有效的。     

Acoustic noise radiated by PWM-controllel induction machine drives

This paper investigates the acoustic noise radiated from two nominally identical induction motors when fed from sinusoidal, and asymmetric regular sampling subharmonic and space-vector pulsewidth modulation (PWM) converters. The theory for analyzing the noise spectrum is developed further to account for the interaction between the motor and the drive. It is shown that manufacturing tolerances can result in significant differences in the noise level emitted from nominally identical motors, and that mechanical resonances can result in extremely high noise emissions. Such resonances can be induced by stator and rotor slot air-gap field harmonics due to the fundamental component of current, and by the interaction between the airgap field harmonics produced by the fundamental and the PWM harmonic currents. The significance of the effect of PWM strategy on the noise is closely related to the mechanical resonance with vibration mode order zero, while the PWM strategy will be critical only if the dominant cause of the emitted noise is the interaction of the fundamental air-gap field and PWM harmonics     

双变量变频器有级调压闭环调速策略研究

文章针对传统的交-交变频器开环控制对转速控制的精度不高、控制难度大的不足,在原有的仅采用控制触发增量方法的基础上加入了有级调压闭环调速控制策略。通过在Matlab/Simulink中引入S函数,建立了分段变频有级调压闭环调速系统的仿真模型,并以双变量变频器为基础设计了实验电路,编写了实验程序,从仿真和实验两个方面对有机调压闭环调速系统的性能进行了分析。最后,得出双变量交-交变频器有机调压闭环调速控制策略具有很高的控制精度,能够提高系统的稳定性的结论。