A digital dual-modulation control for single-phase UPS inverters

A trip-point modulation strategy is proposed for single-phase uninterruptible power supply inverters with an LC filter, which operates simultaneously with pulse-width modulation, named dual-modulation (DM) control. Current estimation and offset current approximation are used conjointly to facilitate the proposed control law. It is shown analytically that the DM control leads to reduced total harmonic distortion (THD) and gains fast transient-state recovery. The simulation and experimental results demonstrate significant amelioration to THD and dynamic state compared to proportional–integral–derivative control under both linear and non-linear loads.     

Predictive current control of voltage-source inverters

A new predictive current controller for a voltage-source inverter is presented in this paper. Practical aspects of realizing the new controller in a system with a digital signal processor (DSP) are considered. Delays introduced by measurements are considered and an improved algorithm with one-period prediction of current is presented. The controller was realized in an experimental system with DSP and field-programmable gate array circuits. Results of the simulations and experiments are presented.     

Design method of single-phase inverters for UPS systems

This article presents the complete design of a low power voltage source inverter (VSI) dedicated for a UPS system. The analysis of the rectangular PWM-AC voltage spectrum allows for a choice of the basic architecture of the inverter. Output filter parameters were calculated to reduce the maximum amplitude of the output VSI voltage harmonics for the steady-state inverter mode. The choice of the feedback loop type was based on a discussion of the inverter output impedance using a continuous model of the inverter. The parameters of the inner loop digital control for the discrete inverter model were calculated using the Coefficient Diagram Method. The influence of the step load was modelled. The time constant of the inverter closed loop system was selected to ensure sufficient system robustness. An outer feedback loop with a plug-in repetitive controller, simplified owing to the properties of the PID/CDM inner loop control, was introduced to eliminate the periodic disturbances generated by the non-linear rectifier load and the deadtime influence. The experimental verification of the design method is presented.     

Measuring the real parameters of single-phase voltage source inverters for UPS systems

The design of a voltage source inverter (VSI) control system requires knowledge about its continuous or discrete model. The output filter inductance and the equivalent serial resistance, which is partly the result of power losses in the core, have values at the operating point that are significantly different from the assigned nominal values, particularly for iron-powder cores. Measurements using standard laboratory equipment are not sufficient because it is impossible to get the voltage and current of the operating point. So the best solution is to measure the Bode plots of the inverter control function at the operating point, to estimate the results of the measurements using the proper analytic function and to calculate the real values of the inverter parameters. Knowledge about the equivalent serial resistance enables the estimation of the inverter power losses. Two approaches to measurements are shown – one that does not require any additional equipment and the other that uses a specialised system to automatically measure the Bode plots. The advantages and disadvantages of both approaches are presented. These measurements enable the validation of the coil core magnetic material by taking into account the power losses. The applications of the measurements in the control design are shown.     

Snubber circuits and losses of voltage-source GTO inverters

The power dissipation of series and parallel snubbers in gate turn-off thyristor (GTO) inverters is investigated. New circuits using optimized snubbers are simulated and compared and solutions that allow the recovery of the energy stored in the snubbers are reported. In particular, an inverter circuit that uses a transformer for the recovery of the energy trapped in the snubbers is investigated, and solutions that avoid saturation of the transformer core are studied     

Microprocessor implementation of a state feedback control strategyfor a current source inverter-fed induction motor drive

The realization of a microprocessor-based controller which implements a complete state-feedback control strategy for a current source inverter-fed induction motor drive is reported. The controller design is based on the application of the pole assignment technique of multivariable system regulation theory to a d,q-axis state-space linearized model of the drive and includes a reduced-order observer to achieve fast regulation and stability. The observer is designed to reconstruct the inaccessible states such as d,q -axis rotor current from a knowledge of the system inputs and outputs. The hardware and software implementation of the controller around an 8085-based microprocessor kit is discussed, and typical test results are presented, along with digital simulation results, to show its performance     

Tuning of leapfrog multiple loop feedback bandpass filters

Off-line tuning of leapfrog multiple loop feedback bandpass filters is demonstrated using a modification of Dishal's method. The proposed method has advantages including simplified tuning circuits and algorithms, minimal additional circuit parasitics and suitability for high frequency applications     

基于状态反馈控制的倒立摆系统分析和设计

针对多输入多输出的倒立摆系统平衡控制,利用牛顿一欧拉方法建立了直线型一级倒立摆系统的数学模型.在分析的基础上,采用状态反馈控制中极点配置法设计了用于直线型一级倒立摆系统的控制器.通过采用MATLAB仿真及其对实际系统的调试验证,表明了该控制器的设计是合理的.     

Analysis, design, and optimization of InGaP-GaAs HBTmatched-impedance wide-band amplifiers with multiple feedback loops

The realization of matched impedance wide-band amplifiers fabricated by InGaP-GaAs heterojunction bipolar transistor (HBT) process is reported. The technique of multiple feedback loops was used to achieve terminal impedance matching and wide bandwidth simultaneously. The experimental results showed that a small signal gain of 16 dB and a 3-dB bandwidth of 11.6 GHz with in-band input/output return loss less than -10 dB were obtained. These values agreed well with those predicted from the analytic expressions that we derived for voltage gain, transimpedance gain, bandwidth, and input and output impedances. A general method for the determination of frequency responses of input/output return losses (or S₁₁, S₂₂) from the poles of voltage gain was proposed. The intrinsic overdamped characteristic of this amplifier was proved and emitter capacitive peaking was used to remedy this problem. The tradeoff between the input impedance matching and bandwidth was also found     

Digital control of an induction motor drive by a stochasticestimator and airgap magnetic flux feedback loop

An approach for the problem of airgap flux estimation in induction motors is presented. The Kalman filter algorithm is developed to provide an estimated state vector containing flux linkage components. The estimated fluxes are then used to implement a direct flux control loop through an inverter-fed AC drive scheme. The overall control system is developed around a digital unit based on a 16 bit microprocessor and a signal processor     

Open loop control of multiple drug effects in anesthesia

Current open-loop computer-controlled infusion pumps do not explicitly control the transient adverse side effects of intravenous drugs during anesthesia. The authors used optimal control principles to synthesize a single-input multiple-output controller that regulates concentrations at the site of desirable drug effect while penalizing excessive side-effect drug concentrations. The cost function incorporates model-based predictions of future effect-site concentrations, and the capability of the anesthesiologist to anticipate upcoming surgical events. The controller was evaluated and then compared with alternative control strategies through computer simulation of a physiologically based pharmacokinetic model for the intravenous drug alfentanil. Multiple-effect control offers an analytic approach to limit the overshoot in adverse side-effect concentrations at the consequence of increasing the time to achieve the desired drug effect     

State feedback controller design of networked control systems

This paper is concerned with the controller design of networked control systems (NCS). A new model of the NCSs is provided under consideration of both the network-induced delay and the data packet dropout in the transmission. In terms of the given model, a controller design method is proposed based on a delay-dependent approach. The feedback gain of a memoryless controller and the maximum allowable value of the network-induced delay can be derived by solving a set of linear matrix inequalities. Two examples are given to show the effectiveness of our method.     

Exact design of continuous-time sigma-delta modulators with multiple feedback DACs

A technique for the exact design of the noise transfer function of Continuous-Time (CT) Sigma-Delta modulators with arbitrary and multiple DAC responses and real op-amps is here presented. The approach, that presupposes linear behavior of active blocks, produces a CT modulator with the same noise shaping as its Discrete-Time counterpart. The method operates entirely in the time domain and accounts for non-idealities of real implementations such as finite gain and bandwidth of integrators. The procedure can be effectively implemented with circuit simulators to allow the exact design with transistor level blocks. A design example on a third-order scheme confirms the effectiveness of the method.     

Rotor-flux-oriented control of a single-phase induction motor drive

This paper investigates the vector control of a single-phase induction motor drive to implement low-cost systems for low-power applications. The static power converter side is implemented using a single-phase rectifier cascaded with a four-switch inverter. The vector control is based upon field orientation concepts that have been adapted for this type of machine. Simulation and experimental results are provided to illustrate the system operation     

Analysis of a sleep-dependent neuronal feedback loop: the slow-wave microcontinuity of the EEG

Increasing depth of sleep corresponds to an increasing gain in the neuronal feedback loops that generate the low-frequency (slow-wave) electroencephalogram (EEG). We derived the maximum-likelihood estimator of the feedback gain and applied it to quantify sleep depth. The estimator computes the fraction (0%-100%) of the current slow wave which continues in the near-future (0.02 s later) EEG. Therefore, this percentage was dubbed slow-wave microcontinuity (SW%). It is not affected by anatomical parameters such as skull thickness, which can considerably bias the commonly used slow-wave power (SWP). In our study, both of the estimators SW% and SWP were monitored throughout two nights in 22 subjects. Each subject took temazepam (a benzodiazepine) on one of the two nights. Both estimators detected the effects of age, temazepam, and time of night on sleep. Females were found to have twice the SWP of males, but no gender effect on SW% was found. This confirms earlier reports that gender affects SWP but not sleep depth. Subjectively assessed differences in sleep quality between the nights were correlated to differences in SW%, not in SWP. These results demonstrate that slow-wave microcontinuity, being based on a physiological model of sleep, reflects sleep depth more closely than SWP does.     

Analysis and characterization of the hyperchaos generated by a semiconductor laser subject to a delayed feedback loop

We characterize the chaotic dynamics of semiconductor lasers subject to either optical or electrooptical feedback modeled by Lang-Kobayashi and Ikeda equations, respectively. This characterization is relevant for secure optical communications based on chaos encryption. In particular, for each system we compute as a function of tunable parameters the Lyapunov spectrum, Kaplan-Yorke dimension and Kolmogorov-Sinai entropy.     

Minimum component high frequency Gm-C wavelet filters based on Maclaurin series and multiple loop feedback

A minimum component high frequency Gm-C wavelet filter structure is presented. A simple function from Maclaurin series approximation is used and the current-mode follow-the-leader feedback structure is employed. For the seventh-order Marr wavelet bandpass filter, the proposed implementation architecture contains only seven ideal Gm-C integrators for poles and one transconductor for zeros. A 100 MHz wavelet filter has been designed and simulated in 0.18 m CMOS and results show the feasibility of the proposed approach.     

Analysis of a quasi-resonant circuit for soft-switched inverters

This paper presents an analysis of a quasi-resonant circuit for soft-switched inverters. The quasi-resonant circuit provides zero-voltage instants for zero-voltage inverter switching by pulling down the DC link voltage momentarily to zero without increasing the peak value of the nominal DC link voltage. Switches in the quasi-resonant circuit can also be turned off at zero current/voltage conditions. The proposed circuit allows creation of zero voltage conditions for inverter soft-switching under loaded and no-load conditions. The operating principle of this circuit is explained, and the analysis of each operating mode is described. Design criteria for achieving zero voltage switching are derived from the general mathematical analysis. Operation of the circuit has been verified by PSPICE simulation and experiments     

Dissipativity-based adaptive and robust control of UPS

In this paper, we investigate the output voltage control for a three-phase uninterruptible power supply (UPS) using controllers based on ideas of dissipativity. To provide balanced sinusoidal output voltages, even in the presence of nonlinear and unbalanced loads, we first derive a dissipativity-based controller using a frequency-domain representation of system dynamics. Adaptive refinements have been added to the controller to cope with parametric uncertainties. Second, based on the first adaptive controller, we propose a controller which turns out to have the proportional-plus-integral-type structure on rotating-frame variables, but with a special design of gain matrices. A sufficient condition in terms of the design parameters is presented for this controller that guarantees stability of the desired equilibrium and robustness against parameter uncertainties. Finally, simulation and experimental results on a three-phase prototype show effectiveness and advantages of the proposed approach