1.在激振器功放上,恒流和恒压设置之间的差别是什么?每种最适合于什么应用?

功放相关问题

Most shakers for general use are set up with current amplifiers. When using some of the more common shaker excitation techniques used today for modal testing, this does not provide for good frequency response measurements. This is especially true for burst random excitation which is very widely used in modal testing with single or multiple shakers. When using burst random excitation, the response of the system needs to decay to zero before the end of the sample interval of the FFT analyzer time capture. With current amplifiers, the armature of the shaker coil is allowed to freely float after the excitation is terminated. For very lightly damped systems, the excitation and response may linger on well beyond the sample interval.

常规使用的大多数激振器设置为电流功放模式。使用某些当今非常常见的激振器激励技术进行模态试验时,这不能提供很好的频响测量结果。对猝发随机激励更是如此,用一个或多个激振器进行模态试验时,使用猝发随机非常普遍。使用猝发随机激励时,系统的响应需要在FFT分析仪时域数据采集时间段的尾部衰减到零。在功放电流模式况下,激励关断后,允许激振器动圈自由浮动。对于非常小的阻尼系统,激励和响应很可能会持续存在,大大超出了采样时间范围。

However, when the amplifier is set up as a voltage amplifier, the back EMF effect (the electromotive force caused by the structure motion driving the shaker armature through the coil) provides resistance to the armature and helps to cause the system response to decay more quickly. This may seem to be inappropriate because the shaker system is then supplying damping to the measurement, but is not an issue as long as the force is measured for the entire measurement. Then the correct input-output relationship is measured. (It is also important to note here that the force needs to be measured and not the electrical parameters of the amplifier in order to make the correct measurement.)

但是,当运放设置为电压模式时,反电动势效应(由结构运动引起的电磁力驱动激振器动圈通过磁芯)对动圈提供阻力,有助于使得系统响应更快地衰减到零。这看上去有可能不合适,因为激振器系统会施加阻尼到测量结果上,但只要对整个测量结果都测量了激振力,就不是问题。(另外这里值得注意的是,为了得到正确的测量结果,需要测量激振力,而不是测量功放的电参数。)