50 results about "Harmonic balance" patented technology

The invention discloses a method for analyzing an inverter on the basis of dual fourier transform. The method comprises the following steps: utilizing an equivalent small parameter method to convert the complex solution for the stable state periodic solution of state variable of the inverter into the solution for a main oscillating component and all-order allowance amplitude; utilizing a harmonic balance method to solve the main oscillating component and all-order allowance amplitude; and finally, adding the main oscillating component with the all-order allowance amplitude, thereby acquiring an analytical expression for the stable state periodic solution of the inverter. According to the method provided by the invention, the stable state periodic solution of the state variable of the inverter can be quickly acquired.

The invention provides a guideway joint feature-considered vibration response analysis method for an upright post-spindle system. Firstly, the relationship between a single roller and the bearing capacity is represented based on the Hertz contact theory, and a relational expression between the load and the deformation is established. After that, in the multiple-support excitation and multiple-support response manner, the inherent frequency and the inherent damping of a guideway joint at each order are identified. Then, a kinetic model for the upright post-spindle system is established. Finally, according to the improved harmonic balance method, the vibration response of the upright post-spindle system under the effect of sinusoidal excitation is calculated. According to the technical scheme of the invention, on one hand, the equivalent stiffness of a roller linear guide rail under an arbitrary load is calculated, and the guideway joint is simplified as a system capable of providing the non-linear restoring force. On the other hand, the nonlinear vibration theory-based calculation method is adopted to provide a vibration model for the upright post-spindle system, and the harmonic balance method is improved. Moreover, a response curve is obtained more quickly based on the principle of least square method. The above method provides a solving means for conducting the accuracy research and the optimized design of linear guide rails.

The invention provides a method for analyzing the nonlinear vibration characteristics of a turbine mechanical blade considering the friction and collision of a damping structure, and the method comprises the following steps of: obtaining the vibration characteristics of the turbine mechanical blade through a finite element method; after the time domain linear finite element dynamic equation of thedisk system, the degree of freedom is reduced by the modal synthesis method to obtain the time domain linear reduction finite element dynamic equation, and then the frequency domain linear reductionfinite element dynamic equation is obtained by the multi-harmonic balance method. The non-linear force vectors on the blade-finite element model of the disk due to contact friction are determined by the Coulomb dry friction model and transformed into turbine blades in the frequency domain. Nonlinear force vectors at all nodes of the roulette disk finite element model, thereby obtaining Nonlinear Reduction Finite Element Dynamics Equation of turbomachinery-Disk in Frequency Domain; then the solution is to draw the turbine blades The frequency response curve of the roulette disc. The invention greatly reduces the calculation time and the calculation cost, thereby greatly improving the efficiency.

The invention relates to a recognizing and locating method for abnormal sound in public places, which belongs to the technical field of audio signal processing. The method uses a double-threshold algorithm and a Welch method to estimate a power spectrum to judge whether the abnormal sound exists in the public places. Feature sequence signals of the abnormal sound are converted into a spectrogram of a time-frequency domain, and problems of feature extraction and classification recognizing of the abnormal sound are solved by using the sparse coding sound recognition technology sensed by hearing. In order to restrain effects of pulse noise in background noise on the abnormal sound locating, non-linear transformation is introduced, and cross-correlation function peak capacity of the abnormal sound is improved. A traditional harmonic balance (HB) weight function is modified, and weight changes caused by low signal-to-noise ration are lowered. Multi-frame data weight processing is introduced, a novel HB weight generalized cross correlation algorithm is suitable for capacity for processing abnormal sound locating in complex acoustic environments in the public places. Due to the fact thatthe method is combined with the sparse coding sound recognition technology based on hearing sense and the modified sound locating technology of time difference of arrival, sound information accompanied with abnormal events can be utilized better, and intelligent level of a monitoring system in the public places can be improved.

A system for a fast method to simulate phase lock loop (PLL) sub-block simulation is presented. The simulation of the sub-blocks of the PLL involve solving a system of non-linear equations for the voltages and currents in the sub-blocks of the PLL. A harmonic balance method is used to solve the system of non-linear equation. The harmonic balance method involves creating a system of linear equations which is solved using a novel hybrid time and frequency domain preconditioner. The hybrid time and frequency domain preconditioner includes the strong and fast convergence property of time-domain preconditioning while avoiding the potential divergent problems of time-domain preconditioning. In addition the hybrid time and frequency domain preconditioner also includes the dependable convergence of frequency domain preconditioning while avoiding the potential stalling problems of frequency domain preconditioning.

The present invention provides a time-domain broadband harmonic domain beamformer and a beamforming method for a circular array. The beamformer includes: a harmonic transformation module and a beam pattern synthesis module. The data received by the array element is sampled and passed through the harmonic transformation module, and then the ring harmonic domain data of each order output by the harmonic transformation module are summed through the corresponding FIR filter to obtain the beam output. Using this beamforming method, the obtained time-domain broadband harmonic domain beam can take into account multiple performance indicators of the beamformer, and can appropriately reduce the number of performance indicators that need to be considered, that is, properly select the cost function and constraint function according to actual needs, Different constraint combinations constitute different beam optimization criteria, so it has strong practicability and wide application adaptability; and the number of channels M in the classical array element domain beamforming is reduced to N+ in the harmonic domain processing of the present invention 1 (where M>2N), reducing the amount of calculation.

The invention discloses a method for searching an instable periodic orbit of a chaotic switching converter, and the method continuously correct a former hypothetical result for the characteristics of the harmonic components of the instable periodic orbit according to the characteristic that a chaotic nonlinear system has periodic traversal through the assumption of the amplitude values of harmonic components of the orbit, the combination of a disturbance method and the principle of harmonic balance and the characteristics of the harmonic components of an inductance / current continuous mode DC-DC switcher at a chaotic state, and finally obtains an analytical expression of the instable periodic orbit relative to a chaotic attractor. The method provides a new idea for the searching of the instable period -n orbit in the inductance / current continuous mode DC-DC switcher at a chaotic state. Because the method is based on the principle of harmonic balance, the obtained instable periodic orbit expression can clearly reflect the harmonic components in the orbit, and can provide design basis for a chaotic controller based on a notching filter / delay feedback.

The invention discloses a vibration analysis method for dry frictional damping mistuned blades with tendons and shroud bands. The method comprises the steps of for actual mistuned states of the blades of a steam turbine, performing three-dimensional contact finite element analysis firstly to obtain support reactions of nodes of contact surfaces of the tendons and the shroud bands of the entire circle of the blades; secondly establishing a contact surface relationship by adopting spring damping units, considering positive pressures, areas and frictional coefficients at the spring damping units, and building a dry frictional damping mistuned vibration analysis model based on a Mindlin micro-sliding friction model and a harmonic balance method; thirdly considering a pre-stress and adopting harmonic response analysis for obtaining convergency values of vibration responses of the blades through iterative solving; and through cyclic calculation, obtaining vibration amplitude response curves of the dry frictional mistuned blades, and performing further extraction to obtain an inherent frequency and a vibration mode. The method is of important significance for dry frictional damping mistuned analysis of the blades and improvement of mistuned bladed disk vibration.

The invention discloses a passive intermodulation circuit interference suppression design method, which belongs to the technical field of circuit design. In this method, the N-type RF coaxial connector is firstly used as the nonlinear source of passive intermodulation to establish a nonlinear equivalent circuit model; The third-order and fifth-order harmonic power values ​​under the power; then the active compensation signals of different frequencies and different powers are transmitted to the equivalent nonlinear circuit together with the useful signal, and the spectrum distribution in the reflected signal and the transmitted signal is simulated. Obtain the system intermodulation interference suppression results based on active compensation signals; in addition, design a passive nonlinear structure and intermodulation feedback network, and observe the changes of forward and reverse intermodulation signals without introducing additional power; finally , choose the scheme with the best suppression effect. The invention is simple and easy to implement, and a scheme with higher economic benefits can be selected to realize a low intermodulation system.