Frequency response

About: Frequency response is a research topic. Over the lifetime, 25705 publications have been published within this topic receiving 332249 citations.

A new control algorithm for three-phase PWM buck rectifier with input displacement factor compensation

Abstract: A new control algorithm for the three-phase buck rectifier with an input filter is developed. The algorithm employs a separate control loop for compensation of the input current displacement factor in steady-state, in addition to the standard output voltage regulation loop. The algorithm allows separate design of the input filter and of closed loop output voltage control. The design procedure is explained and illustrated on an example. The algorithm is verified experimentally on an 1-kW, 100-kHz, three-phase isolated buck power converter. >

Integrated tunable inductance network and method

Abstract: An integrated, tunable inductance network features a number of fixed inductors fabricated on a common substrate along with a switching network made up of a number of micro-electromechanical (MEM) switches. The switches selectably interconnect the inductors to form an inductance network having a particular inductance value, which can be set with a high degree of precision when the inductors are configured appropriately. The preferred MEM switches introduce a very small amount of resistance, and the inductance network can thus have a high Q. The MEM switches and inductors can be integrated using common processing steps, reducing parasitic capacitance problems associated with wire bonds and prior art switches, increasing reliability, and reducing the space, weight and power requirements of prior art designs. The precisely tunable high-Q inductance network has wide applicability, such as in a resonant circuit which provides a narrow bandwidth frequency response which peaks at a specific predetermined frequency, making possible a highly selective performance low noise amplifier (LNA), or in an oscillator circuit so that a precise frequency of oscillation can be generated and changed as needed.

Practical transfer function estimation and its application to wide frequency range representation of transformers

Abstract: A widely applicable, general methodology for estimation of transfer function parameters from frequency response data is presented. The procedure is based on the solution of a linear least squares problem by the singular value decomposition (SVD). The condition of the problem is discussed and approaches referred to as shifting and scaling are introduced in order to reduce the condition number. To extend the application to practical cases with measurement errors and/or a large number of poles, a partitioned estimation method with Gauss-Seidel iterations is developed. An iterative improvement process with constraints on the poles is applied to increase the accuracy and to avoid the possibility of obtaining unstable poles. The application of the suggested method of estimation to the representation of transformers is presented with practical examples. Either transfer function or state equation representation can be obtained for transformers described by their terminal frequency responses. >

Leak detection in pipelines by frequency response method

Abstract: A new technique for the detection of leaks in a pipeline is presented utilizing its frequency response. In the system frequency response, a leak increases the amplitude of pressure oscillations at the even harmonics. Such an increase in amplitude has an oscillatory pattern; the frequency and amplitude of this pattern may be utilized to predict the location and discharge of a leak. In this technique, the pressure transient history at one location is sufficient and the history of the transient in the pipe prior to leak is not needed; this makes it advantageous over a number of other existing techniques, in addition to being simpler to use. It is shown that the technique successfully detects the location of a leak in a number of simple systems with leak discharge as low as 0.2% of the steady discharge. The technique is verified by comparing the results with those computed by using the method of characteristics. Practical issues and limitations for field implementations are discussed.