Transfer Function Of Inverter Research Articles

Transfer Learning of Model-Based Neural Network for Transfer Function Inversion and Load Monitoring of Wind Turbines

One main concern when using a generic model of a wind turbine is how can we apply it on real measurements for different turbines of the same type. This paper gives a first answer by proposing an inversion approach of a transfer function. Then that approach is tested on a real test case. Two transfer functions from two different turbines of the same farm are inverted on SCADA measurements with transfer learning of a model-base neural network. The inversion results show better predictions than ones with a transfer function classically trained with LIDAR data. An application to the prediction of damage equivalent load with a generic model is showed: the results of applying the inverted transfer function is compared to real DEL measurements and to the transfer function trained from LIDAR data.

Development of Prototype Fractional Order Controller for a Grid-Tied Photovoltaic System

This paper presents design of a robust fractional order proportional-integral (FO-PI) prototype controller for a grid connected photovoltaic (PV) system. The robustness in face of parameter variation is handled by designing a suitable controller considering sensitivity function, gain margin and phase margin for both inner and outer control loops. As FO-PI controller is not yet available in physical form and due to complexity involved in grid-tied PV system, we propose an alternative way of hardware implementation of inner loop FO-PI controller by using fractor through RC ladder network. Firstly, an emulator circuit of the inner current loop comprising the FO-PI controller (including fractor and the proportional gain) along with the transfer function of inverter and filter is developed and the response is verified through a real-time simulator (OPAL-RT). Finally, the FO-PI part of the emulator circuit is interfaced with the PC target to form a hardware-in-loop (HIL) by employing OPAL-RT. The performance of the complete system is verified through OPAL-RT simulator. The result shows the improved robustness by the proposed control design method.

Use of Virtual Forward Propagation Network Model to Translate Analog Components

Neural computing is an emerging research topic today due to its massive increase in demand and applications for machine learning. In this virtual simulation research work, using a free software, a program has been trained a neural network model and translate its functionality into the hardware. In the context of analog neural network, this research seeks to verify a shift sigmoid function that can approximate the transfer function of CMOS inverter. By showing this approximation accurately and reducing the number of components, it would help to implement the neural network based integrated chips. A conciliation is selected for the distance matric of the proposed function. This distance metric between the given CMOS transfer function and the shifted sigmoid function is minimized using the gradient descent. However, this approximate transfer function of CMOS inverter is chosen to verify in a three-layer perceptron networks. The network topology randomly generates weights to provide a diverse set of truth tables. We report two networks whose weights are chosen randomly using a back propagation algorithm due to volatile nature of the network topology and the activation function. The results of this research conclude that the transfer function of CMOS inverter is able to approximate the CMOS transfer function adequately for the purposes of these perceptron networks.

Repetitive Controller With Phase-Lead Compensation for Cuk CCM Inverter

This paper proposes a repetitive controller with phase-lead compensation for an unfolding-type Cuk continuous conduction mode (CCM) inverter operating in the CCM. The Cuk CCM inverter features medium power capacity, step up/down ability, and low input/output current ripples, so it is well suited to distributed power generation systems. To achieve accurate tracking of the reference output current, we make the use of the repetitive controller coupled with a conventional proportional-integral controller and a nominal duty ratio. In developing the proposed controller, we use the average model of the Cuk CCM inverter in the grid-connected case. The two right-half plane (RHP) zeros in the transfer function of the Cuk CCM inverter cause phase lag of the closed-loop system; to compensate for the phase lag, we implement a phase-lead compensation algorithm in the repetitive control scheme. We also provide detailed and practical design guidelines of the control parameters to develop a stable Cuk CCM inverter. Experimental tests using a 500-W Cuk CCM inverter demonstrate the desirable performance of the proposed control approach.

Influence of Z ‐Source output impedance on dynamic properties of single‐phase voltage source inverters for uninterrupted power supply

The study presents the problem of the influence of the Z-Source circuit output impedance on the small signal control transfer function of a voltage source inverter (VSI). The previously published inverter design algorithms did not take into account the output impedance of the DC/DC voltage step-up converters. The presented considerations should estimate the necessity of taking into account the Z-Source output impedance when designing an efficient control system for a DC/AC voltage inverter. It will be shown that the influence of the Z-Source storing energy in the inductances can be notable for low damping resistances and that it introduces two additional resonant frequencies to the nominator and denominator of the VSI control transfer function that are very close to each other. The magnitude Bode plots of the control transfer function of a VSI with a Z-Source are presented. The breadboard verification is also included.

Normalized estimate of adaptive filter for non-minimum phase transfer function component: An illustrative case study

This paper presents an analysis of a normalized estimate of an adaptive finite impulse response (FIR) filter for a non-minimum phase transfer function component for the application of a minimum phase kepstrum filter (a ratio of minimum phase filters) to a one-sample delay filter in a beamforming structure. Based on the analysis, it will be shown that a normalized estimate by an adaptive FIR filter is characterized as only one non-minimum phase term from an unknown non-minimum phase system because the adaptive FIR filter estimates a consistent non-minimum phase term in a normalized form from both direct transfer function and its inverted transfer function. Furthermore, it will be shown that the characterized non-minimum phase term from the estimate by the adaptive FIR filter can identify an actual non-minimum phase transfer function component that can be used to evaluate the reverberant level in a realistic environment by monitoring only one zero position from pole-zero placements.

계통 연계형 태양광 인버터에서 최대 출력 점 추적 제어

태양 에너지는 재생 가능하고 오염이 없는 특성으로 바람직한 에너지원이다. 계통에 이용하기 위해서는 dc-dc 컨버터와 계통 연계 dc-ac 인버터가 필요하다. dc-dc 컨버터는 태양광 시스템이 높은 dc전압에 동작하기 위하여 필요하고, 인버터는 계통에 연결하기 위하여 필요한 전압과 주파수를 만들어 내는데 필요하다. 본 논문에서는 첫째로 단상 계통 연계 인버터에서 전류 루프 전달 함수가 유도되고, 둘째로 컨버터 측에서 컨덕턴스 증가 방식의 MPPT 방식이 제안하여 인버터 측에 최대 전력을 공급하는데 있다. 시뮬레이션 결과가 계통에서 태양광 인버터 시스템의 성능과 특성을 보여준다.

Admittance Compensation in Current Loop Control for a Grid-Tie LCL Fuel Cell Inverter

Current loop transfer function of a single-phase grid-tie inverter has been systematically derived with representations of conventional transfer function format using admittance terms for controller design and loop compensation. The power circuit adopts the LCL type filter to allow universal output that can be operated in both standalone and grid-tie modes. The proposed admittance compensation along with a quasi-proportional-resonant controller is designed to achieve high gain at the fundamental frequency while maintaining enough stability margins. The entire current loop controller and admittance compensation have been simulated and tested with a 5-kW fuel cell prototype. Without the admittance path compensation, simulation results indicate that the system cannot start up smoothly and the zero current command cannot be tracked very well. At first simulation cycle, the power flow erratically fed back to the inverter that may cause catastrophe failure. With admittance path compensation, the time-domain current steady-state error can be easily reduced with the loop gain design in frequency-domain. Simulation and experimental results show that the inverter is capable of both standalone and grid-tie connection mode operations and smooth power flow control even with zero current command.

Repetitive PD control strategy with inverse transfer function compensation for CVCF inverter

A novel repetitive control strategy for the output waveform of single-phase CVCF inverters is presented. In this scheme, the inverse transfer function of inverter is used as a compensator to obtain stable and satisfy harmonic rejection. Besides, PD controller is adopted to improve transient performance. Simulation and experimental results, which are gotten from a DSP-based 400Hz, 5.5KW inverter, indicate that the proposed control scheme can achieve not only low THD during steady-state operation but also fast transient response during load step change.

Solutions to disturbance decoupling problem with constant measurement feedback for linear systems

We study in this paper the problem of disturbance decoupling with constant (i.e., static) measurement feedback (DDPCM) for linear systems. For a class of systems which have a left invertible transfer function from the control input to the controlled output or a right invertible transfer function from the disturbance input to the measurement output, we obtain a complete characterization of all solutions to the DDPCM. For a system that does not satisfy the above invertibility condition, we use the special co-ordinate basis to obtain a reduced-order system. Then a complete characterization of all possible solutions to the DDPCM for the given system can be explicitly obtained, if the obtained reduced-order system itself satisfies the invertibility condition. The main advantage of these solutions is that the solutions are given in a set of linear equations. This resolves the well known difficulty in solving non-linear equations associated with the DDPCM.

Simultaneous [formula omitted] optimal control : The state feedback case

A simultaneous H 2 H ∞ control problem is considered. This problem seeks to minimize the H 2 norm of a closed-loop transfer matrix while simultaneously satisfying a prescribed H ∞ norm bound on some other closed-loop transfer matrix by utilizing dynamic state feedback controllers. Such a problem was formulated earlier by Rotea and Khargonekar ( Automatica, 27, 307–316, 1991) who considered only so called regular problems. Here, for a class of singular problems, necessary and sufficient conditions are established so that the posed simultaneous H 2 H ∞ problem is solvable by using state feedback controllers. The class of singular problems considered have a left invertible transfer function matrix from the control input to the controlled output which is used for the H 2 norm performance measure. This class of problems subsumes the class of regular problems.

On system identification for linear minimum variance prediction or control

We consider system identification of a linear model to be used for linear minimum variance prediction or control. Gaussian noise processes with everywhere positive spectral density may be assumed to be generated via an invertible transfer function. We consider non-Gaussian noise processes whose spectral density is everywhere positive and whose generation involves a non-invertible transfer function. We show that system identification based on least-squares and (incorrectly) assuming invertibility of this transfer function leads to results nonetheless useful for linear minimum variance prediction or control.

Achieving Macroeconomic Goals

Two basic approaches to using dynamic econometric models to formulate macroeconomic policy are generally in use. These are: invertible transfer function methodology and optimal control methodology. In this paper a technique for determining dynamic growth paths is presented. The result of the application of this technique is the synthesis of the two approaches into a single approach yielding a policy with more desirable characteristics than was previously possible. An example of the use of this synthesis technique using Pindyck's model is presented.

1st-order-type models for multivariable process control

It is well known in classical feedback control that many high-order linear time-invariant systems can be approximated, for the purpose of feedback design, by a low-order state-space model due to the presence of approximately cancelling poles and zeros in the system-transfer function. The paper presents an equivalent technique in the case of a multivariable system described by a strictly proper m × m, minimum-phase and invertible transfer-function matrix G(s) by the application of the contraction-mapping theorem. It is shown that, in many cases of practical interest, a multivariable 1st-order-type model is adequate for the purpose of control-system design, and that such a model can be determined directly from transient response data or, equivalently, by the analysis of the high- and low-frequency characteristics of the system. The application of the technique is illustrated by the analysis of a high-order binary-distillation-column model and the dynamics of a counter-flow heat exchanger.