5 results about "Describing function" patented technology

The application discloses a bidirectional CLLLc state observation control method based on extended describing function modeling, belongs to the field of power electronic technology application, and is based on solving the wide voltage output of the bidirectional CLLLc converter and the output voltage stability problem under different load working conditions, and through the establishment of a bidirectional CLLLc harmonic equivalent circuit, the establishment of a large signal model by using an extended describing function, the approximate linearization of the model by using partial derivatives and steady-state solutions, the creation of a bidirectional CLLLc converter state observation equation, and the design of a controller, accurate control of the bidirectional CLLLc converter is realized. The state observation matrix of the application is related to the circuit topology and system control parameters, and therefore the bidirectional CLLLc converter state observation control method based on the extended describing function modeling is suitable for DC / DC conversion under various application scenarios, and under different degrees of load working conditions, the effect of stable output voltage is achieved.

The invention provides an H infinite dynamic output feedback control method of an SS type IPT system. The method comprises the following steps: constructing an extended description function state space model of the SS type IPT system; an integral error between a reference signal and actual output is introduced on the basis, and an augmented system model is established in combination with external disturbance and measurement noise; based on a Lyapunov function and an H infinity performance index, sufficient conditions of asymptotic stability and disturbance suppression performance of a closed-loop system are deduced and converted into a linear matrix inequality to be solved, so that gain parameters of a dynamic output feedback controller are directly obtained. Under the condition that external disturbance and measurement noise exist, accurate tracking of the reference signal by the system load voltage can still be guaranteed, the robustness and the fault-tolerant capability of the system are improved, meanwhile, dependence on alternating current side variable measurement is avoided, and the method has high engineering application value.

The invention discloses a time domain stability analysis and improvement method for an LLC resonant converter, and the method comprises the steps: solving and generating a Jacobian matrix of the LLC resonant converter according to an extended description function method; solving all characteristic values of the Jacobian matrix; judging the stability of the closed-loop system of the LLC resonant converter according to a Lyapunov indirect method; if the system is stable, outputting a judgment result; if the system is not stable, PI controller parameters are adjusted, or the characteristic value sensitivity of a certain element beta in the matrix is solved, the size of the element beta in the matrix is adjusted based on the characteristic value sensitivity solving result, then the characteristic value is solved again, and the stability is judged. According to the scheme, the system stability influence trend is reflected through time domain analysis, the effects of stability improvement and system instability prevention are achieved, the influence of the load on the stability of the converter is analyzed through the characteristic value sensitivity, the influence trend of the load change on the stability is estimated according to the characteristic value distribution track, the controller acts in advance, and system instability is avoided.

This invention provides a linearization fitting analysis method for the output frequency control system of a dual-frequency induction heating power supply. It unifies the coordinated compensation triggered by frequency increment limiting, frequency increment rate of change limiting, and minimum frequency interval constraints into a synthetic nonlinear module. Under quasi-steady-state and small-disturbance conditions, a describing function is used to equivalently linearize this synthetic nonlinear module, obtaining the equivalent gain related to the fundamental amplitude of the two input channels and forming an equivalent linear frequency domain model. Subsequently, frequency domain windows are selected near the high-frequency and low-frequency operating bands, and a unified structure second-order equivalent model is fitted to the equivalent frequency response, obtaining two sets of isomorphic low-order model parameters for the high-frequency and low-frequency channels. Based on these parameters, the frequency compensation increment required for feedforward compensation is quickly calculated to reduce online computation and improve real-time performance. When the fitting residual exceeds a preset threshold or enters a strongly nonlinear operating condition, model parameter updates and model calls are stopped, and the linearization fitting analysis is exited.

The invention discloses a network construction type converter impedance calculation method and system considering an amplitude limiting link and a computer readable storage medium. The method comprises the following steps: establishing an expression of voltage and current closed-loop control considering the amplitude limiting link; establishing an impedance model of a target network construction type converter system; carrying out nonlinear modeling based on a description function on an amplitude limiting link; setting an initial signal amplitude A and an initial frequency, and substituting the initial signal amplitude A into formulas (2)-(4) to obtain an impedance value of the nonlinear improved admittance model of the constructed network type converter under the initial frequency; and gradually increasing the frequency value, calculating the impedance value of the non-linear improved admittance model of the network-building converter under each frequency until the updated frequency reaches the target frequency band, and obtaining the impedance value under the target frequency band. The method makes up for the deficiency of a small signal impedance model in the aspect of analyzing a nonlinear link in converter modeling, and has the advantages of being scientific and reasonable, good in applicability, clear in mechanism and the like.