51 results about "Harmonic balance" patented technology

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 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 present invention discloses a symbolic analysis method and apparatus of a fractional order switching converter operating under continuous current mode. On the basis of the harmonic balance principle, the method converts a process of solving non-integer-order calculus operation into a processing of matrix operation and linear equation group solution by converting state variable fractional order differential operation in the converter into differential operators and combining all of the differential operators into a diagonal semiotic matrix. Compared with an existing analysis method of establishing an Oustaloup filter approximate model in Matlab / Simulink which is frequently used for a fractional order switching converter, the method can analytically analyze state variable ripple peak-to-peak values of the converter and the influence of order change of an energy storage element on the working condition of the converter, can rapidly obtain analytical solution of a steady state period of state variables, and can also be used for analyzing harmonic components of the state variables.

The invention relates to a complex frequency domain calculation method for a converter transformer alternating current and direct current composite electric field, which comprises the following steps:obtaining a finite element equation by combining a Galerkin method based on a full current density continuity equation of a lossy medium; expressing each periodic variable in the equation under the AC / DC composite excitation by using a complex stage number; obtaining a unit matrix equation by using the equal harmonic coefficients, and superposing all the units to obtain a system matrix equation;introducing fixed-point conductivity, and converting an iterative equation into distribution according to harmonic frequency by performing row and column change on the matrix; and selecting fixed point conductivity, carrying out iterative solution according to a set convergence criterion, and carrying out convergence to obtain a potential value. According to the method, the finite element stiffness matrix of each iteration is decomposed according to the harmonic frequency by adopting a fixed-point method, so that the memory consumption of a harmonic balance algorithm is reduced, and the calculation cost for analyzing a nonlinear alternating-current and direct-current composite electric field can be effectively reduced.

The invention discloses a nonlinear kinetic equation solving method and system for mechanical nonlinear vibration analysis. The method comprises the following steps: constructing and obtaining a nonlinear finite element kinetic equation in a system time domain according to a to-be-analyzed mechanical nonlinear vibration system; obtaining a nonlinear finite element kinetic equation in a frequency domain through a multi-harmonic balance method; solving a Jacobian matrix of a nonlinear finite element kinetic equation in a frequency domain by utilizing an automatic differential method; solving thenonlinear finite element kinetic equation in the frequency domain by adopting an arc length method to obtain a solution of the nonlinear finite element kinetic equation in the frequency domain; according to the solution of the nonlinear finite element kinetic equation in the frequency domain, the solution of the nonlinear finite element kinetic equation in the time domain is obtained through generalized inverse Fourier transform, then a frequency response curve is obtained, and mechanical nonlinear vibration analysis is carried out.

The invention discloses a second harmonic balance detection-based time jitter delay measurement device, which comprises a first half transparent and half reflecting mirror, a second harmonic generation medium, a second half transparent and half reflecting mirror, a time delay line, a first photoelectric detector, a second photoelectric detector, a differential circuit, a third half transparent and half reflecting mirror, a first reflector, a second reflector, a first focusing mirror, a second focusing mirror, a third reflector, a first to-be-measured pulse input interface, a second to-be-measured pulse input interface and a differential signal output interface. According to the technical scheme of the invention, a second harmonic balance detection mechanism is used, according to the characteristic that output of an electric signal is 0 in the case of no delay, time jitter delay is measured, a requirement that time jitter delay has a high measurement resolution is achieved, and applications to a high-precision time synchronization system are facilitated.

The invention discloses an inductance current interrupted mode fractional order switch converter symbol analysis method combining a harmonic wave balance principle; the method converts differential operation relating to status variable fractional order in a converter into differential operators, and combines all differential operators into an opposite angle symbol matrix, thus converting a non-integer order calculus operation solving process into a matrix operation and linear equation (group) solving process. Compared with a conventional normal analysis method, aiming at the fractional order switch converter, of building an Oustaloup filter approximation model in a Matlab / Simulink, the novel method can parse and analyze converter status variable ripple peak-to-peak value size and influences on converter work status by energy storage element order changes, can fast obtain a status variable stable state periodic analytic solution, and can parse status variable harmonic wave components.

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 discloses a flexible flight dynamics modeling method considering structural nonlinearity. The method comprises the following steps: establishing an aircraft flight dynamics equation containing nonlinear aeroelastic wings by using an unsteady aerodynamic force; fitting the relationship between the hysteresis nonlinear generalized force and the displacement by adopting a rational formula, so as to establish an aircraft flight kinetic equation containing nonlinear rigidity and nonlinear damping at the same time; and finally, solving response characteristics and stability of the nonlinear flight dynamics model by using a numerical method or a harmonic balance method. The unified expression form for describing the nonlinearity of the structure established by the invention can solve the problems of aircraft gap nonlinear dynamic modeling and subsequent dynamic analysis under the conditions of installation gaps between control surface hinges and connecting pieces, aging and loosening of parts and the like, so that a guiding idea is provided for related controller design; and the method has a certain engineering application value.

The invention discloses a method for calculating a transient solution of a fractional-order CCM switching converter. An equivalent small-parameter method is utilized to convert complicated fractional-order differential operation into exponential operation of a differential operator, accordingly calculation of a complicated fractional-order converter state variable steady-state period solution is converted into calculation of the amplitudes of a direct component and harmonic components, and a harmonic balance method can be utilized for the calculation of the amplitudes of the direct component and the harmonic components; the transient solution of a fractional-order switching converter state variable can be obtained only by analyzing the transient solution of a main vibration equation of a fractional-order switching converter state variable and then combining with the steady-state solution of the equation. The transient process of the fractional-order CCM switching converter can be well analyzed by adopting the method.

The invention discloses a symbolic analysis method for a resonant wireless power transmission system based on a Class-E inverter. According to the method, through combination of a harmonic balance principle, a complicated solution process of a multi-state variable circuit satisfying a ZVS (Zero Voltage Switching) condition is converted into a process of matrix operation and linear equation (set) solution. Compared with an existing modeling analysis method, the method has the advantages that the peak-to-peak ripple magnitude of a state variable of a convertor and an influence of an order change of an energy storage element on a working state of the convertor can be analytically analyzed, under the condition of not increasing the orders of a state equation, a steady state periodic analytical solution of the state variable can be obtained rapidly, and the method can be used for analyzing a harmonic component of the state variable.

A computer-implemented method computes the steady-state and control voltage of a voltage controlled oscillator, given a known frequency or a known period of oscillation of the voltage controlled oscillator. Differential algebraic equations representative of the voltage controlled oscillator are generated, where the differential algebraic equations includes a known period or frequency of oscillation and an unknown control voltage of the voltage controlled oscillator. The differential algebraic equations are modified using a finite difference method, a shooting method, or a harmonic balance method, to obtain a set of matrix equations corresponding to the differential algebraic equations. A solution to the matrix equations is obtained using a Krylov subspace method, using a preconditioner for the Krylov subspace method that is derived from a Jacobian matrix corresponding to the matrix equations, where the solution includes the control voltage of the voltage controlled oscillator in steady state.

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.

Vibrations of a principal machine are reduced at the fundamental and harmonic frequencies by driving the drive motor of an active balancer with balancing signals at the fundamental and selected harmonics. Vibrations are sensed to provide a signal representing the mechanical vibrations. A balancing signal generator for the fundamental and for each selected harmonic processes the sensed vibration signal with adaptive filter algorithms of adaptive filters for each frequency to generate a balancing signal for each frequency. Reference inputs for each frequency are applied to the adaptive filter algorithms of each balancing signal generator at the frequency assigned to the generator. The harmonic balancing signals for all of the frequencies are summed and applied to drive the drive motor. The harmonic balancing signals drive the drive motor with a drive voltage component in opposition to the vibration at each frequency.

The invention provides a bolt connection cylindrical shell structure dynamic characteristic calculation and analysis method, and belongs to the technical field of mechanical dynamics. The method comprises the following steps: establishing a cylindrical shell energy equation according to a plate-shell theory; establishing a load excitation equation according to the external load condition; establishing a bolt connection mechanical equation according to the bolt connection characteristics; solving bolt connection equivalent stiffness and equivalent damping according to first-order Fourier decomposition; accurately expressing different load characteristics through component force in each vibration displacement direction; obtaining a forced vibration differential equation of the bolt connection cylindrical shell structure through a Lagrange equation; and solving the dynamic characteristics of the bolted connection cylindrical shell structure by applying an incremental harmonic balance method. The method starts from the establishment of a bolted connection equivalent mechanical model, is applied to a cylindrical shell structure, achieves the solving of the vibration response according to the demands of different actual working conditions, simplifies the modeling and calculation process, is high in precision, is high in universality, and the like.

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.

In a circuit simulation tool in a computer system having one or more computer processors and computer-readable storage, a method for characterizing a driven oscillator circuit having an oscillator coupled to a time-varying input signal includes retrieving information provided in a circuit description of the oscillator circuit. The method also includes forming a frequency-domain harmonic balance equation for the oscillator circuit using the retrieved information provided in the circuit description of the oscillator circuit. The harmonic balance equation includes a first differential operator in a frequency domain of the input signal and a product of a differential operator in a second frequency domain of the oscillator and a frequency variable of the oscillator. The frequency variable is independent of the frequency domain of the input signal. The method further includes solving the harmonic balance equation to obtain a waveform description of the oscillator circuit.

The invention relates to a limit cycle oscillation-based rapid friction identification method of an electromechanical servo system. The method comprises the steps of firstly, respectively describing a linear model of the electromechanical servo system and an unknown friction module of a parameter by mathematical expressions; secondly, enabling the system to generate self-oscillation by adjusting gains of two relays, and measuring data of periodic motion; and finally, performing arithmetical operation according to a principle formula obtained by a harmonic balance condition, and calculating the parameter of the friction model. By the method, the friction model of the electromechanical servo system can be rapidly and accurately identified, a mathematical model can be provided for design of the servo control system, and the design efficiency of the electromechanical servo system is improved. Since the method is small in computation, an excitation signal is not needed to meticulously design, and the method is convenient and rapid, is easy to implement and is suitably used for the design of a high-precision electromechanical servo system.

The invention discloses a radio frequency power amplifier harmonic balance parameter extraction method based on a neural network, and the method comprises the steps: firstly obtaining sample data of harmonic balance parameters of a tested HEMT power amplifier under different bias conditions which comprise the drain-source voltage, drain current, frequency and input power of a device, wherein the harmonic balance parameters comprise output power, power gain, power additional efficiency and a third-order intermodulation point; training the neural network by using the sample data to finally obtain a trained HB harmonic balance parameter neural network; for the HEMT power amplifier to be tested, inputting the bias condition of the HEMT power amplifier to be tested into the HB harmonic balanceparameter neural network, and enabling the HB harmonic balance parameter neural network to output the harmonic balance parameter of the HEMT power amplifier under the bias condition. According to themethod, the harmonic balance parameters of the radio frequency power amplifier can be efficiently and accurately extracted.

The invention discloses an optimum design method based on overall performance of a terahertz frequency band device. The method comprises the steps of during optimum design, establishing stepped structure characterization impedance step transformation characteristics of a transmission line by extracting characteristic parameters of cell structures of the transmission line; after a proper terahertz diode is selected for use, establishing a diode circuit model at a needed working frequency band; establishing a complete whole device circuit model based on the designed device; carrying out optimization design of harmonic balance simulation by setting an objective function taking the overall device performance as an optimization target to obtain an optimal result; after that, combining according to structure parameters of the optimized cell structures of the transmission line, establishing a whole passive structure model of the related device, carrying out integral simulation of a passive circuit, and verifying a simulation result again to check whether the result still meets indexes or not; if not, returning to the previous step for adjusting until the result meets design requirements. The optimum design method is used for designing the terahertz frequency band device, and is accurate and efficient in design.

The invention discloses a harmonic balance method device of a single-degree-of-freedom system and belongs to the field of computer engineering application. The device comprises a nonlinear system configuration part, a symbolic variable definition part, a computation part and an output part, wherein an objective function construction unit is arranged in the computation part and is used for dynamically constructing an objective function needed for optimizing and solving mean values, amplitudes of each harmonic and phases. A harmonic balance method adopted by the device only considers limited harmonic in response and divides the harmonic into a low-frequency harmonic portion and a high-frequency harmonic portion. Starting from that the low-frequency portion only includes mean values and first harmonic, the solving accuracy is improved through optimization and iteration, times of the highest harmonic contained by the low-frequency portion are continuously increased, the lowest harmonic of the high-frequency harmonic portion is reduced at the same time, the result obtained through computation by using the low-frequency harmonic portion is used as an initial value, and finally the mean values in response, the amplitudes of the limited harmonic and the phase are solved. The device provided by the invention has the advantages of very fast convergence speed and very high accuracy.

The invention discloses a passive intermodulation circuit interference suppression design method, and belongs to the technical field of circuit design. The method comprises the following steps: firstly, taking an N-type radio frequency coaxial connector as a non-linear source for generating passive intermodulation, and establishing a non-linear equivalent circuit model; performing harmonic balancesimulation on the circuit system, so that third-order and fifth-order harmonic power values of the connector under required frequency bands and required power can be obtained; transmitting active compensation signals with different frequencies and different powers and useful signals to an equivalent nonlinear circuit together, simulating spectrum distribution in the reflection signals and the transmission signals, and obtaining a system intermodulation interference suppression result based on the active compensation signals; besides, designing a passive nonlinear structure and an intermodulation feedback network, and observing changes of forward and reverse intermodulation signals under the condition that extra power is not introduced; and finally, selecting a scheme with an optimal inhibition effect. The method is simple and easy to implement, and a scheme with higher economic benefit can be selected to realize a low-intermodulation system.

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 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.

A dynamic instability recognition method based on a tension leg parameter atlas comprises the following steps that 1, a motion power equation with system damping for tension legs is built; 2, a harmonic balance incremental method is adopted for constructing infinite determinant matrix; 3, a nonlinear dynamic equation stability parameter diagram with damping is obtained; 4, the motion power stability parameter atlas with damping for the tension legs is drawn; 5, inhibitory effects of damping for system instability in different stability regions are determined; 6, according to the inhibitory effects of damping for system instability in different stability regions, power instability parameter recognition is obtained. According to the method, tension leg platform power instability can be rapidly recognized on the sea, and the problem of tension leg excessive stress failure or fatigue damage is solved; meanwhile, the tension leg and platform marine installation cost and risk are greatly lowered; the marine installation speed is increased, and the project quality and working efficiency are improved.

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 is suitable for the field of electrical technology, and provides a vibration displacement calculation method and device for an electrical equipment iron core and terminal equipment. The method comprises the steps: calculating a vector magnetic potential according to a mass matrix and a magnetic field stiffness matrix of a target iron core and an electric field parameter of an electric field where the target iron core is located, and calculating the magnetic field distribution corresponding to the target iron core; calculating a Maxwell force corresponding to the target iron core according to the magnetic field distribution; inputting the mass matrix, the magnetic field stiffness matrix and the Maxwell force into a preset mechanical vibration equation, and solving the vibration displacement of the target iron core based on a harmonic balance method. According to the method provided by the invention, the influence of a mass matrix, a magnetic field stiffness matrix and Maxwell force on vibration is fully considered in a mechanical vibration equation, and the accuracy of vibration displacement calculation can be improved; a harmonic balance method is applied in the solving process, the vibration displacement can be calculated in the frequency domain, the calculation speed can be increased, and a basis is provided for harmonic analysis of the vibration displacement.