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Hysteresis current control is an attractive nonlinear current-control method for voltage source inverters when a fast system response is required. A well-known disadvantage of hysteresis current control is that the system has to operate over a wide switching frequency range. This causes an increase in the switching losses of the system and increases the difficulty in designing the output filter. The recently proposed parabolic current control solves this problem by employing a pair of parabolic carriers as the control band. Through the use of parabolic current control, constant switching frequency can be achieved. In the implementation of parabolic current control, dead time is employed to prevent shoot through of the inverter leg. The employment of dead time impacts the current-tracking precision and the stability range of the parabolic current-control method. Another side effect of using dead time is that the switching frequency deviates from the desired value. In this paper, the effects of dead time on parabolic current control are analyzed, and a compensation method is proposed for voltage source inverters that use parabolic current control. Using the output current direction of the voltage source inverter, a new pair of improved parabolic carriers is derived. As a result, the current error can be well controlled and the effects of dead time can be eliminated. The improvement in the current tracking of the system comes with an added benefit where the duty cycle range is extended. The effectiveness of the proposed dead-time compensation method is experimentally verified by the use of a full-bridge voltage source inverter. [ABSTRACT FROM AUTHOR]

This paper presents a method of online identification of the parameters of permanent magnet synchronous motors (PMSM) by model reference adaptive identification based on Popov Super Stability Theory. Firstly, the relations of parameters in the Field Orientation Control (FOC) system are analysed. Secondly, the proposed identification method of PMSM concerns two parts. In the case of high-speed operation of the motor, the method can accurately identify the inductance indq-axis and the permanent magnet (PM) flux linkage. On the other hand, in the case of low speed, it can accurately identify the winding resistance of the stator. The method does not require additional excitation signals, but only makes use of motor voltage, current and their deviations. Thirdly, a simple and effective dead-time compensation method has been applied to inhibit the dead-time effects on the parameter identification. At last, the simulation and experiment results clearly demonstrate the validity and feasibility of the method. [ABSTRACT FROM PUBLISHER]

Inverters play a central role in modern society including renewable energy integration and motor drives. Due to the inherent switched nature of the inverter waveforms harmonic distortion is an issue. Additionally, the switching patterns are perturbed by unavoidable switching delays. Amongst those, nonlinear and load-dependent switching delays (known as inverter ‘dead-time delays’) are the most difficult to compensate. In this paper, we propose a new approach to delay compensation and harmonic suppression in inverter voltage. The proposed approach is based on variable prediction horizon nonlinear model predictive control. [ABSTRACT FROM AUTHOR]

Dead-time element must be set into space vector pulsed width modulation signals to avoid short circuits of the inverter. However, the dead-time element distorts the output voltage vector, which deteriorates the performance of electrical machine drive system. In this paper, dead-time effect and its compensation control strategy are analyzed. Based on the analysis, the voltage distortion caused by dead-time is regarded as two disturbances imposed on dq axes in the rotor reference frame, which degenerates the current tracking performance. To inhibit the adverse effect caused by the dead-time, a control scheme using two linear extended state observers is proposed. This method provides a strong ability to suppress dead-time effects. Simulations and experiments are conducted on a permanent magnet synchronous motor drive system to demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Abstract: Chlorine disinfection of wastewater at the Kanapaha Water Reclamation Facility in Gainesville, Florida was investigated to design an appropriate feedback controller because this facility has a large and variable dead-time. Cascade control and dead-time compensation were applied to control the performance of this type of system using the method of characteristics and odometric transformation. The cascade control scheme features a slave controller with a probe located proximate to the dosage point; therefore, this system can be tuned efficiently. The other controller in the cascade is a master controller that adjusts the set point of the slave controller. The master is affected by a large and variable dead-time. However, by using the odometric transformation, the reactor model can be written as a system with a constant dead-time. An odometric transformation replaces time with β in the model and transforms the system dynamics to a constant time delay model. The method of characteristics was used to transform the partial differential equations for the chlorine disinfection reactions into ordinary differential equations. Afterward, the Smith predictor was used to design a dead-time compensation for the master controller. The resulting equations were solved numerically, and the maximum numbers for the reactor and control variables were calculated using an open loop simulation program. The delays were calculated for each system, and the highest delay was calculated when the numbers for the reactor were the maximum. The simulation suggests that a 20-s time increase is adequate for conducting a discrete approximation for the continuous system. [ABSTRACT FROM AUTHOR]

A modified direct torque control (DTC) method based on torque angle is proposed for interior permanent-magnet synchronous motor (IPMSM) drivers used in electric vehicles (EVs). Given the close relationship between torque and torque angle, proper voltage vectors are selected by the proposed DTC method to change the torque angle rapidly and regulate the torque quickly. The amplitude and angle of the voltage vectors are determined by the torque loop and stator flux-linkage loop, respectively, with the help of the position of the stator flux linkage. Furthermore, to satisfy the torque performance request of EVs, the nonlinear dead-time of the invertor caused by parasitic capacitances is considered and compensated to improve steady torque performance. The stable operation region of the IPMSM DTC driver for voltage and current limits is investigated for reliability. The experimental results prove that the proposed DTC has good torque performance with a brief control structure. [ABSTRACT FROM AUTHOR]

Highlights: [•] A Smith predictor based prediction scheme with a tuning parameter is proposed. [•] The control design is based on the delay-free model of the plant. [•] Uncertain unstable plants with large time delay are considered. [•] A tradeoff between disturbance performance and robustness can be achieved. [Copyright &y& Elsevier]

This study presents a new software-based plug-in dead-time compensator for grid-connected pulsewidth modulated voltage-source inverters of single-stage photovoltaic (PV) systems using predictive current controllers (PCCs) to regulate phase currents. First, a nonlinear dead-time disturbance model is reviewed, which is then used for the generation of a feed-forward compensation signal that eliminates the current distortion associated with current clamping effects around zero-current crossing points. A novel closed-loop adaptive adjustment scheme is proposed for fine tuning in real time the compensation model parameters, thereby ensuring accurate results even under the highly varying operating conditions typically found in PV systems due to insolation, temperature, and shadowing effects, among others. The algorithm implementation is straightforward and computationally efficient, and can be easily attached to an existent PCC to enhance its dead-time rejection capability without modifying its internal structure. Experimental results with a 5-kW PV system prototype are presented. [ABSTRACT FROM AUTHOR]

In this paper, a fully integrated high-sensitivity patch-clamp system is proposed for single-molecule deoxyribonucleic acid (DNA) analysis using a nanopore sensor. This system is composed of two main blocks for amplification and compensation. The amplification block is composed of three stages: 1) a headstage, 2) a voltage-gain difference amplifier, and 3) a track-and-hold circuit, that amplify a minute ionic current variation sensed by the nanopore while the compensation block avoids the headstage saturation caused by the input parasitic capacitances during sensing. By employing design techniques novel for this application, such as an instrumentation—amplifier topology and a compensation switch, we minimize the deleterious effects of the input-offset voltage and the input parasitic capacitances while attaining hardware simplicity. This system is fabricated in a 0.35 \mum 4M2P CMOS process and is demonstrated using an \alpha-hemolysin protein nanopore for detection of individual molecules of single-stranded DNA that pass through the 1.5 nm-diameter pore. In future work, the refined system will functionalize single and multiple solid-state nanopores formed in integrated microfluidic devices for advanced DNA analysis, in scientific and diagnostic applications. [ABSTRACT FROM PUBLISHER]

This study presents an analysis about state estimation and dead‐time compensation effect over constrained control systems with bounded disturbances and dead‐time. It is shown that input‐to‐state stability and constraint satisfaction can be guaranteed by using an equivalent dead‐time free system with measurable states and modified disturbances. This result may be useful to simplify synthesis and analysis of a given constrained control strategy. A linear output feedback control scheme and a tube‐based model predictive control strategy are used as motivating examples. [ABSTRACT FROM AUTHOR]

Abstract: In the present paper a dead-time compensating proportional-integral-derivative (DTC–PID) controller with anti-windup action is derived. The proposed controller also can be configured as a PID controller or as a dead-time compensating PI (DTC–PI) controller. For stable, integrating and unstable processes, approximated with the first-order plus dead-time (FOPDT) model, robust tuning procedure is derived for the DTC–PI controller. Optimization of the regulatory performance of the DTC–PID controller is based on the frequency response of higher-order models, under constraints on the robustness and sensitivity to measurement noise. Excellent performance/robustness trade-off is obtained for stable, integrating and unstable processes, including dead-time, as confirmed by simulations and by experimental results obtained on a laboratory thermal process. [Copyright &y& Elsevier]

Abstract: This paper studies the  optimization problem for systems with adobe input delay. These are systems having only two (possibly vector) input channels: one is delay free and the other is delayed. We present a solution based on the reduction of the problem to an equivalent delay-free problem via simple loop shifting arguments. This results in a solution based on two standard algebraic Riccati equations, which are associated with the delay-free version of the problem. The optimal controller is in the dead-time compensator form. We also derive an explicit and transparent expression for the cost of delay and (in the case when the problem is solvable without the delayed channel) a numerically stable form of the optimal solution, which includes exponentials of Hurwitz matrices only. The approach is readily extendible to more general multiple input/output delay cases. [Copyright &y& Elsevier]

Conventional hysteresis current controllers have the disadvantage of a variable switching frequency. This paper presents a novel hysteresis current control method which uses the adjacent current error zero-crossing time to calculate the upper/lower hysteresis bandwidth after the measured half current error period. This strategy makes the algorithm independent of load parameters and thus it can achieve a stable switching frequency. An improved switching scheme has been successfully applied to a single-phase three-level H-bridge voltage source inverter driving a vibration test bench based on the novel hysteresis current. It can select appropriate switching states to overcome dead-time effects without dead-time compensation according to the relation of the current switching state, the current error, and the upper/lower hysteresis bandwidth. Field-programmable gate array has enough computational power to allow multiple sampling within a current error period and logic control power to implement state machine transitions. The simulation and experimental results are given to demonstrate the validity and features of the novel hysteresis current controller with the improved switching scheme. [ABSTRACT FROM AUTHOR]

To ensure the double-fed induction generator (DFIG) works safely, dead-time was added to the driving signals. When DFIG works stably, the frequency of rotor current is low, and the effect of dead-time is noteworthy. Distortion of output voltage of the rotor side converter, zero-current clamping phenomenon and asymmetry of PWM pulses would be caused by the addition of dead-time. To eliminate the effect of dead-time, the paper analyzed the influence of it and improved the existing dead-time compensation methods. A compensation strategy was proposed by dividing the space of current vector into six regions in each of which only one phase voltage needed to be compensated. To ensure the symmetry of PWM pulses, the comparison value of PWM generation needed to be modified twice in a switch cycle. The proposed method was tested on the DFIG experiment platform. With the current waveforms before and after dead-time compensation compared, the current with compensation was remarkably better. [ABSTRACT FROM AUTHOR]

The application of multilevel converters for exciting permanent-magnet machines with low-phase inductance to dc-link voltage ratios facilitates a reduction in high-frequency switching harmonics. However, converter nonlinearities and, in-particular, ON-state device voltage drops, create additional low-frequency harmonics. This paper therefore proposes a generic compensation scheme to accommodate the effects of such converter nonlinearities and, in doing so, improve the harmonic quality of the machine phase currents. Experimental results gathered from a prototype five-level diode-clamped converter validate the benefits of the proposed scheme by showing quantitative reductions in low-frequency harmonics. [ABSTRACT FROM AUTHOR]

This paper presents an effective online approach for dead-time compensation using a simple vectorial disturbance estimator in permanent-magnet synchronous motor (PMSM) drives. The proposed estimator can calculate the disturbance voltages, which are induced by dead time, by the use of simple vector operations, i.e., the inner and outer products of flux linkage increments and a unit back electromotive force function. Then, to compensate the effect of dead time, the estimated disturbance voltages are feed forwardly added to the current control loop. This method is applied to the 750-W laboratory PMSM drive to show its effectiveness. [ABSTRACT FROM AUTHOR]

A new dead-time compensation method for vector-controlled ac motor drives is proposed. The method only compensates the fundamental and sixth harmonic component of the inverter-output distortions in synchronous reference frame. The fundamental component is compensated by feedforwardly adding a predetermined compensation signal to the voltage reference of ac motor drive. To compensate the harmonic distortions, the harmonic compensator with all-pass-based adaptive bandpass filter is proposed and builds up the feedback loop with current controllers in order to minimize the distortions due to dead-time effects. The method is software intensive and independent of the polarity of the phase currents and nonlinear-switching characteristics varied with operating conditions of the inverter. It is simulated and implemented on a 750-W laboratory ac motor drive, where its effectiveness is verified. [ABSTRACT FROM AUTHOR]

A mechanical sensorless drive system for an interior permanent-magnet synchronous motor, for which parameters including the inverter are identified, is proposed in this paper. The rotor position is estimated by a signal-injection sensorless scheme at standstill. The resistance, including the on-resistance of the insulated-gate bipolar transistor, the voltage error caused by the dead time of the inverter, and the d-axis and q-axis inductances are identified at standstill using the estimated position. After the motor starts by the signal-injection sensorless control, the sensorless scheme changes to a scheme based on the extended electromotive force estimation, which uses the identified parameters. The magnet flux linkage is also identified under the sensorless operation. The effectiveness of the proposed method is verified by several experimental results. [ABSTRACT FROM AUTHOR]

Conventional dead-time compensation methods, for pulsewidth-modulated (PWM) inverters, improve the current output waveforms; however, the zero-current crossing effect is still apparent. This letter proposes a new method, based on angle domain repetitive control, to reduce the distortions in the PWM inverters output waveforms caused by the dead time and the zero-crossing problem. [ABSTRACT FROM AUTHOR]

This note studies lumped-delay approximations of distributed-delay control laws. It is shown that approximation problems reported in some recent studies are caused by a brutal combination of poor approximation accuracy in the high-frequency range (a non-strictly proper approximation of a strictly proper transfer function) and excessive sensitivity of the design method to high-frequency additive plant uncertainties. It is also shown that a safe implementation can be achieved by eliminating either of these two factors. Some remedies toward this end are proposed. [Copyright &y& Elsevier]

The article reviews the results of a number of recent papers dealing with the revision of the simplest approaches to the control of first-order time-delayed systems. The concise introductory review is extended by an analysis of two discrete-time approaches to dead-time compensation control of stable, integrating, and unstable first-order dead-time processes including simple diagnostics of the model used and focusing on the possibility of simplified but reliable plant modelling. The first approach, based on the first historically known dead-time compensator (DTC) with possible dead-beat performance, is based on the reconstruction of the actual process variables and the compensation of input disturbances by an extended state observer (ESO). Such solutions play an important role both in a disturbance observer (DOB) based control and in an active disturbance rejection control (ADRC). The second approach considered comes from the Smith predictor with two degrees of freedom, which combines feedforward control with output disturbance reconstruction and compensation by the parallel plant model. It is shown that these two approaches offer advantageous properties in the case of actuator limitations, in contrast to the commonly used PID controllers. However, when applied to integrating and unstable first-order systems, the unconstrained and possibly unobservable output disturbance signal of the second solution must be eliminated from the control loop, due to the hidden structural instability of the Smith predictor-like solutions. The modified solutions, usually referred to as filtered Smith predictor (FSP), then no longer provide a disturbance signal and thus no longer fully fit into the concept of Industry 4.0, which is focused on further optimization, predictive maintenance in dynamic systems, diagnosis, fault detection and fault identification of dynamic processes and forms the basis for the digitalization of smart production. Nevertheless, the detailed analysis of the elimination of the unstable disturbance response mode is also worth mentioning in terms of other possible solutions. The application of both approaches to the control of a thermal process shows almost equivalent quality, but with different dependencies on the tuning parameters used. It is confirmed that a more detailed identification of the controlled process and the resulting higher complexity of the control algorithms does not necessarily lead to an increase in the resulting quality of the transients, which underlines the importance of the simplified plant modelling for practice. [ABSTRACT FROM AUTHOR]

The research object of this paper is single-phase PWM rectifier, the purpose is to reduce the total harmonic distortion (THD) of the grid-side current. A model predictive current control (MPCC) with fixed switching frequency and dead-time compensation is proposed. First, a combination of an effective vector and two zero vectors is used to fix the switching frequency, and a current prediction equation based on the effective vector's optimal action time is derived. The optimal action time is resolved from the cost function. Furthermore, in order to perfect the established prediction model and suppress the current waveform distortion as a consequence of the dead-time effect, the dead-time's influence on the switching vector's action time is analyzed, and the current prediction equation is revised. According to the experimental results, the conclusion is that, firstly, compared with finite-control-set model predictive control, proportional-integral-based instantaneous current control (PI-ICC) scheme and model predictive direct power control (MP-DPC), the proposed MPCC has the lowest current THD. In addition, the proposed MPCC has a shorter execution time than MP-DPC and has fewer adjusted parameters than PI-ICC. In addition, the dead-time compensation scheme successfully suppresses the zero-current clamping effects, and reduce the current THD. [ABSTRACT FROM AUTHOR]

A simple and iterative algorithm is devised in this letter with the help of the small-gain theorem to determine the current polarities of pulsewidth-modulation voltage-source-inverter drives. Experimental results are also presented to show the effectiveness of the method when used in the dead-time compensation. [ABSTRACT FROM AUTHOR]

To prevent short-circuits between the upper and lower switches of power converters from over-current protection, the dead time is mandatory in the switching gating signal for voltage source converters. However, this results in many negative effects on system operations, such as output voltage and current distortions (e.g., increased level of fifth and seventh harmonics), zero-current-clamping phenomenon, and output fundamental-frequency voltage reduction. Many solutions have been presented to cope with this problem. First, the dead-time effect is analyzed by taking into account factors such as the zero-clamping phenomenon, voltage drops on diodes and transistors, and the parameters of inverter loads, as well as the parasitic nature of semiconductor switches. Second, the state-of-the-art dead-time compensation algorithms are presented in this paper. Third, the advantages and disadvantages of existing algorithms are discussed, together with the future trends of dead-time compensation algorithms. This article provides a complete scenario of dead-time compensation with control strategies for voltage source converters for researchers to identify suitable solutions based on demand and application. [ABSTRACT FROM AUTHOR]

This paper proposes a novel three-phase voltage source inverter dead-time compensation strategy for accurate compensation in wide current regions of the inverter. In particular, an analysis of the output voltage distortion of the inverter, which appears as parasitic components of the switches, was conducted for proper voltage compensation in the low current region, and an on-line compensation voltage controller was proposed. Additionally, a new trapezoidal compensation voltage implementation method using the current phase was proposed to simplify realizing the trapezoidal shape of the three-phase compensation voltages. Finally, when the proposed dead-time compensation strategy was applied, the maximum phase voltage magnitude in the linear modulation voltage regions was defined to achieve smooth operation even at high modulation index. Simulations and experiments were conducted to verify the performance of the proposed dead-time compensation scheme. [ABSTRACT FROM AUTHOR]