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This article discusses the dynamic characteristics of static multi-valued elements and structures that characterize the quality of operation. Obtained an equation of the dynamics of multi-valued closed systems, determining the dynamic properties of static multivalued memory element in the vicinity of the equilibrium states of a closed system and allows clarifying the issues of system stability, oscillation...
This paper examines the accuracy of the zero-order hold (ZOH) model of the digital pulsewidth modulator (DPWM). The influence of the computational delay on the precision of this equivalent DPWM model is discussed in detail. A compensation method is proposed to compensate the deviation of this DPWM model for accurately calculating the stability region with different computational delay and duty-cycle...
The main theme of this paper is to propose a self-commissioning technique for high bandwidth servo drives. The presented self-commissioning technique include auto-identification of servo motor parameters and on-line calculation of controller gains of servo drives. The electrical parameters required for current controller, including stator resistance and inductance are identified under standstill....
LCL-type grid-connected inverter is largely utilized in renewable generation system due to high harmonic suppression. In order to tackle the resonance issue induced by LCL-type filters, grid-side current feedback active damping method (GCFADM) without extra sensors has been extensively investigated. However, the damping characteristic under GCFADM has not been fully evaluated. In this paper, an improved...
Conventional resonant controllers (RCs) are commonly used in the current control of grid-tied converters with LCL filter due to their advantages, such as zero steady-state error at both fundamental sequences, easy design process, and straightforward implementation. Nevertheless, these traditional solutions do not permit to place the closed-loop poles of the system in convenient locations when dealing...
With the rapid development of computer networks, a variety of network applications continue to emerge, resulting in a surge of network data traffic. Therefore, the network congestion becomes more serious. Congestion control is facing many problems, including latency, fairness, stability and so on, especially the instability of the network caused by transmission delay. We introduce the traditional...
An improved deadbeat plus plug-in repetitive control scheme is proposed for grid-connected three-phase four-leg inverters to achieve fast and accurate feed-in grid current tracking. Discrete-time mathematical model of the three-phase four-leg grid-connected inverter is developed. An improved deadbeat (DB) plus plug-in repetitive control (RC) scheme is proposed to reject periodic disturbances while...
A continuous-time Delta-Sigma modulator (CTDSM) using passive low pass-filter (LPF) in the feedback DAC is proposed. The LPF helps to reduce the signal swing and slew-rate requirements of the first amplifier in CTDSM and also contributes one-order noise shaping. A modulator synthesis is analyzed. The performance of the modulator has been verified through simulations using a standard 0.18-μm CMOS process...
In Network Control Systems (NCSs), a dual rate controller is an approach that is applied to reduce the influence of packages loss and random delays. If the output measuring sensors is slower than the control action update can be reached, the dual rate controller is used as a possible solution. In this paper, a fuzzy controller will be combined with a dual rate controller in an NCS to regulate the...
This paper investigates the mean-square stabilizability of a networked discrete-time linear feedback system with multi-step random delay induced by a communication channel. It is assumed that the probability mass function (PMF) of the random delay is known. According to this model, an averaged channel transfer function and the spectral density of the channel uncertainty caused by the delay are obtained...
SAR echo simulator plays an important role in space-borne SAR development. The echo delay precision in the SAR echo simulator reflects the quality of the echo, which is limited due to the limited AD sampling rate. In this paper, a non-integer delay filter algorithm based on Lagrange interpolation is proposed to realize the precise echo delay, which uses the approximation in frequency domain. The results...
In this paper, an enhanced form of modified Smith predictor (EMSP) is designed for the control of higher order stable systems. The higher order process, whose controller design is practically difficult, is reduced into first order plus delay (FOPDT) and second order plus delay (SOPDT) and thereby designing controllers capable to control servo and regulatory problems of its original higher order process...
Low delay maximally flat in passband and equiripple in stopband (MFER) FIR Digital Differentiators (DDs) are known to have high differential accuracy with low delay. The transfer function is defined as the subtraction of the stopband function from the passband function. The passband function and the stopband function realizes flatness characteristics and equiripple characteristics, respectively. However,...
We treat the design problem of second-degree IIR digital differentiators. The design problem (cost function) is formulated in the quadratic form without any frequency sampling. Since the cost function is the quadratic form, the solution is unique and the optimization scheme does not require any recursive optimization. Hence, the procedure of the design for the second-degree differentiators is very...
In this paper an approximation algorithm allowing to calculate parameters of rational and fractional continuous-time transfer functions as well as transfer functions being their series connections with delay from the identified frequency response is proposed. Parameters of the mentioned transfer functions are obtained by an optimisation algorithm utilizing ideas of randomized search. The presented...
This paper introduces a speed-enhanced incremental ADC architecture for high-resolution low-power sensor applications, incorporating a third-order sturdy MASH modulator. Unlike previous sturdy MASH ADCs, owing to the properly modified loop filters in the 2-1 sturdy MASH, the quantization noise of the first noise-shaping loop could be cancelled out. The proposed ADC with a 4b coarse SAR ADC and a 2-1...
An analytical model of power supply noise induced jitter (PSIJ) at inverter chains is proposed. Based on the piecewise linear approximated I-V curve model, closed-form equations of PSIJ transfer function at a single inverter are derived. The PSIJ transfer function of an inverter chain output is then obtained by linearly stacking the single inverter-PSIJ transfer functions. Accuracy of the proposed...
Conventionally, a fractional-N synthesizer is simulated using a closed-loop behavioral model and the simulations can be very time-consuming. With the analysis by Perrott et al., a more straightforward model, namely the feed-forward model, for the fractional-N frequency synthesizer is available. The feedforward model simulations provide quick, relatively accurate evaluation of fractional-N synthesizer...
This paper deals with the control of simple process models where multiple time-delays appear. These delays can be input, output or state delays. For the case of input/output time-delays, a general solution is retrieved from the literature. For state time-delays, the scalar case is considered and a pre-compensator is used to cancel the delay. The proposed algorithms are applied to the control of a...
In order to ensure the effective operation of condensing steam turbine, a vacuum control method with double compensation loops is developed to solve the problem of condenser vacuum. Firstly, the system identification is carried out according to the measured data of the condenser, and the mathematical model for the condenser vacuum pressure, the flow rate of circulating water and the regulating valve...
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