Cycle Control Technique Research Articles

An improved one cycle control technique for switching buck regulators

An improved one cycle control technique for switching buck regulators

An improved one cycle control technique for switching buck regulators

An improved one cycle control technique for switching buck regulators

Robust limit cycle control for finite-time generation of sustained oscillations in nonlinear systems with mixed dead-zone and saturation

This paper suggests a novel limit cycle control technique, based on the finite-time stability scheme, for producing sustained oscillations in a class of nonlinear complex systems. The considered systems are constrained to input dead-zone and saturation simultaneously and suffer from non-vanishing perturbations due to model uncertainties, and external disturbances. For this purpose, an innovative sliding manifold is proposed based on the topology of the wanted limit cycle which provides the conditions for developing the finite time stability concept for limit sets. With the aid of the finite-time command filter and the cooperation of the sliding mode control (SMC) method with the backstepping technique, a robust controller is constructed which guarantees the finite-time convergence of phase trajectories of the closed-loop system toward the wanted limit cycle. This leads to the creation of sustained oscillations, with the desirable amplitude and frequency, in the system's output. The stability analysis is proved based on the Lyapunov approach through the set stability concept. Finally, the effectiveness of the suggested methodology is confirmed by a variety of simulations.

A simple duty cycle control technique to minimize torque ripple in open-end winding induction motor

Modern electric vehicles (EVs) that drive an induction motor (IM) fed by a traction inverter are fast gaining popularity due to their simple configuration and robustness. The direct torque control (DTC) technique is one of the best control methods to drive the IM, especially in open-end winding configurations, as it offers more voltage vectors. However, the existence of hysteresis controllers and improper switching technique causes larger torque ripples that leads to variable switching frequency. The study will be focused on the open-end winding induction motor where the direct current (DC) power is fed from both sides of the stator windings using the dual inverter configuration. To minimize the torque ripples, a simple switching technique using the duty cycle control method is proposed by injecting a high-frequency square wave into the default inverter switching status to form the new pattern of voltage vectors. The effectiveness of the proposed technique is tested through MATLAB/Simulink software and validated experimentally with a lab-scale setup using a dSPACE controller. The findings show that the proposed method reduces torque ripple by over 50% while keeping the DTC's simple structure.

Metaheuristic Algorithm Based Maximum Power Point Tracking Technique Combined With One Cycle Control For Solar Photovoltaic Water Pumping Systems

Solar photovoltaic technology has become eminent in the world because of its clean and abundant nature and can be effectively used for water pumping applications. A maximum power point tracking method is indispensable to achieve the best benefit from photovoltaic systems. Conventional maximum power tracking methods become successful only under uniform irradiance conditions and fail to track the maximum power under partial shading conditions (PSC). Hence, nature-inspired metaheuristic algorithms were proposed to track the optimum power under varying environmental conditions. This study proposes a method for improving the performance of the nature-inspired maximum power point tracking algorithms by using a nonlinear control technique called one cycle control. Based on the duty cycle obtained from the tracking algorithm the one cycle control technique generates pulses for the DC–DC converter, which is connected to a brushless DC motor pump system through a voltage source inverter. The performance of the proposed system under various PSCs is validated using the Cuckoo search, particle swarm optimization, and grey wolf algorithms. Simulation results for various shading patterns prove the supremacy of the system with respect to convergence speed, tracking efficiency, robustness, steady-state oscillations at maximum power point, and initial exploration oscillations in comparison with systems without one cycle control. In addition, the introduction of a KY converter as a DC–DC converter reduces the output voltage ripple in the system. Thus, the proposed system with one cycle control overcomes the disadvantages of the existing methods and can be effectively utilized for water pumping applications.

Photovoltaic Cell Energy Transfer System Using Series-Connected Bidirectional Resonant Converters

This paper presents an energy transfer system for a photovoltaic module with solar-powered panels, batteries, and a grid-tie inverter that uses series-connected bidirectional resonant converters. The purpose of this study is to investigate the asymmetrical duty cycle control and frequency control techniques for increasing and controlling the input voltage of the grid-tie inverter. Prior to the experiment, the performance of the bidirectional resonant converters was evaluated using a simulation program. By adjusting the asymmetrical duty cycle by 50%, the input voltage of the grid inverter was found to be 48.2 V. However, by adjusting the asymmetrical duty cycle by 10%, the input voltage of the grid inverter was 150.4 V. Furthermore, when turning on the switch in the zero-voltage switching (ZVS) mode, the converter circuit was controlled and operated within an appropriate frequency range. The results revealed no switching losses when the converters were turned on. As a result, the bidirectional resonant converters were able to properly transfer energy and regulate the input voltage of the grid inverter.

PI Regulator-Based Duty Cycle Control to Reduce Torque and Flux Ripples in DTC of Six-Phase Induction Motor

In this paper, a proper duty cycle control method is proposed to reduce torque and flux ripples and harmonic loss in direct torque control (DTC) of six-phase induction machine (6PIM). Three different methods are proposed to improve the performance of switching table DTC for 6PIM. First, by the suitable selection of two vectors in each sampling period, the harmonic amplitude is significantly decreased, but the torque and flux ripples are still large. Then, the abovementioned method is combined with duty cycle control technique and the torque and flux ripples and current harmonics are significantly reduced. In addition, the switching frequency is also reduced by selecting the suitable voltage vector in each sampling period. Finally, a simple control method is suggested to calculate the duty ratio of voltage vectors independently of machine parameters. Although neglecting the one-step delay makes performance of the final technique similar to the previous one, considering this delay in real conditions shows the following advantages for the final method: less torque and flux ripples, less current harmonics, simplicity, and constant switching frequency. Despite these improvements, all duty cycle-based DTC approaches (duty-DTC and PI-duty-DTC) increase the inverter switching losses. The simulation and experimental results presented in this paper verify the performance advantages of the proposed methods.

A four-switch shunt active filter based on one cycle control for compensating non-linear loads

ABSTRACT This paper introduces a Four-Switch Three-Phase Shunt Active Power Filter (FSTP-APF) based on One Cycle Control (OCC) technique for compensating the currents of three phase non-linear loads. The power stage of FSTP-APF uses only four semiconducting switches which leads to reduce the overall cost of APF. The proposed technique retains the advantages of the conventional OCC, such as no reference current calculation, no need for using Phase-Locked Loop (PLL), very simple control circuit and constant switching frequency. In addition, the modification reduces the number of semiconductor switches, reduces the filter output inductances, reducing the number of sensors to only four sensors, two of them for measuring supply currents and the others for measuring DC-link voltages, and the control algorithm becomes simpler. The feasibility and performance of the proposed technique are demonstrated through the simulation and experimental verifications.

A Computationally Efficient FCS-MPC Method Without Weighting Factors for NNPCs With Optimal Duty Cycle Control

In this paper, a computationally efficient finite control-set model predictive control (FCS-MPC) method without weighting factors is proposed for nested neutral point-clamped converters (NNPCs) with optimal duty cycle control. The aim of this paper is to design a modification of the FCS-MPC scheme that improves the steady-state performance, as well as to avoid the weighting factors selection while remaining computationally feasible. First, in order to improve the calculation efficiency, a simplified computational method is proposed by introducing the Lyapunov principle into the design of sector distribution method based on space vector modulation technique, and eliminates unwanted switching states. Second, aiming at improving the steady-state control performance, an optimal duty cycle control technique is incorporated into the proposed FCS-MPC strategy to determine the time duration of the selected voltage vector. In that sense, a new FCS of candidate voltage vectors with different duty cycles are synthesized without sacrificing the simplicity of the control structure. Besides, in order to avoid the selection of weighting factors, the proposed method replaces the single cost function with simplified multiobjective optimization strategy based on a fuzzy-decision-making method. Finally, the performance of the proposed strategy for NNPCs is evaluated by simulation studies in various operating conditions.

Generation of stable oscillations in uncertain nonlinear systems with matched and unmatched uncertainties

ABSTRACTIn this paper, a robust limit cycle control technique is proposed for generation of stable oscillations in a class of uncertain nonlinear systems with both matched and unmatched uncertainties. For this purpose, first, the modified Lyapunov function is introduced which is appropriate for stability analysis of invariant sets (instead of equilibrium points). The structure of the proposed Lyapunov function is related to the shape of the desirable limit cycle. Next, in order to design the robust limit cycle control input, the backstepping and Lyapunov redesign methods are employed, simultaneously. The The classical Lyapunov redesign controller is discontinuous and robust with respect to matched uncertainties. To overcome unmatched uncertainties, a modified version of the Lyapunov redesign controller is suggested in each step of backstepping which results in a continuous robust control law. Furthermore, the convergence of the phase trajectories of the uncertain closed-loop system to the target limit cycle is proved using the extended Lyapunov stability theorem. Finally, computer simulations are performed to show the applicability of the given approach. In this regard, two uncertain nonlinear practical systems are considered and robust stable oscillations are generated in these systems via the proposed controller. Simulation results confirm the effectiveness of the proposed technique.

Variable Duty Cycle Control for Quadratic Boost PFC Converter

Compared with constant duty cycle-controlled discontinuous conduction mode (DCM) boost power factor (PF) correction (PFC) converter, constant duty cycle-controlled quadratic DCM–DCM boost PFC converter features with much lower second-order line frequency output voltage ripple, and however, it suffers from low PF. To increase PF of quadratic DCM–DCM boost PFC converter, a variable duty cycle control technique for quadratic DCM–DCM boost PFC converter is presented in this paper. An approximation equivalent for the variable duty cycle is employed to simplify the implementation circuit. The corresponding expressions of PF and output voltage ripple are analyzed. For input voltage range of 100–240 Vac, quadratic DCM–DCM boost PFC converter with variable duty cycle control benefits with very high PF, and tradeoff between PF and output voltage ripple of this converter is analyzed. Experimental results from 100-W prototypes are given to verify the theoretical analysis.

Voltage regulation of a stand-alone self-excited induction generator using STATCON with one cycle control technique for wind energy conversion system

ABSTRACTThis paper presents the simple voltage regulation scheme using a three-phase static VAr compensator (STATCON) for a stand-alone self-excited induction generator (SEIG) that uses variable-speed wind generation system. Most of the loads are inductive and need an equal amount of leading VArs, which is generated by the STATCON and injected at point of common coupling instantaneously. The one cycle control technique is considered and modified to implement for VAr compensation of SEIG voltage regulation. To emphasis the controller characteristics, a STATCON is designed for a 3-Ø, 0.75 kW, 415 V, 1.8 A Induction Machine and tested in simulation using MATLAB/SIMULINK software.

Voltage and Frequency Control of Variable Speed Induction Generator using One Cycle Control Technique

Induction generators are widely used to extract the energy from renewable sources, particularly as a wind power generator either grid connected or isolated operation. The problem associated with stand-alone mode operation is voltage and frequency control. An electronic load controller is used for frequency / voltage control. It uses PI controller to generate the gating signal for the DC chopper. This method has the fault of bad dynamic response and thedistortion of output voltage at zero-crossing. To overcome the defect of PI controller when steady state error is equal to zero, a one cycle control technique suggested and implemented. Simulation of wind driven self-excited induction generator (SEIG) performance is studied and results are discussed.

Three‐leg inverter configuration for simultaneous dual‐frequency induction hardening with independent control

Parts of certain objects need hardening. Hardening is a heat treatment process which can be achieved by induction heating. Certain objects like gears require alternating source with two different frequencies. Simultaneous application of dual frequencies is desirable for proper hardening of a gear. This study proposes a three-leg inverter topology with a load resonant circuit which can provide independent and simultaneous control of low-frequency (LF) and high-frequency (HF) currents through the load coil. The load circuit is a combination of two series resonant circuits which operates at the desired LF and HF. Power control is achieved with phase modulation and asymmetric duty cycle control techniques. A 240 W prototype of the proposed dual-frequency inverter is implemented and tested. Experimental results obtained are in good agreement with the simulation results.

A 7.5 GS/s flash ADC and a 10.24 GS/s time-interleaved ADC for backplane receivers in 65 nm CMOS

This paper presents a 7.5 GS/s, 4.5 bit flash analog-to-digital converter (ADC) for high-speed backplane communication. A two-stage track-and-hold (T/H) structure enables high input bandwidth and low power consumption at the same time. A sampling clock duty cycle control technique, which allocates more tracking time to the bandwidth-limited second T/H stage, facilitates high sampling rates. A digital offset correction scheme compensates both random and systematic offsets due to process variation and T/H amplifier gain nonlinearity, simultaneously. Two test-chip prototypes were fabricated in a 65 nm CMOS process. Experimental results of a standalone ADC chip demonstrate 3.8 effective number of bits (ENOB) at 7.5 GS/s. The figure-of-merit (FOM) of the standalone ADC is 0.49 pJ/conversion-step. The second test chip combines two ADCs together in order to demonstrate a time-interleaved ADC (TI-ADC) for use in high-speed backplane receivers. The TI-ADC operates at 10.24 GS/s while achieving 3.5 ENOB and 0.65 pJ/conversion-step FOM.

Implementation of One Cycle Control Technique in Dc-Dc Buck Converter

A nonlinear control technique is used to controls the duty ratio (T) of a switch in switching converters. i.e., an improved one cycle control technique which is conceptual to the concept of technique of one cycle control. This one cycle control method gives firmness to the source side disturbances, but this technique shows infirmness with the load side disturbances. The proposed new improved one cycle control technique rectifies the drawbacks of one cycle control technique. It strongly rejects both source side disturbances and load side disturbances. Simulations with the buck converter results using MATLAB are given to verify the proposed work. To implement and demonstrate the feasibility of this new control technique over the disturbance, an experimental buck converter prototype has been designed, built, and tested. Keywords: DC-DC Switching Converter, Integrator, Non linear Control, One -Cycle Control Technique, PI Adjustor

Buck-Boost Interleaved Inverter Configuration for Multiple-Load Induction Cooking Application

Induction cooking application with multiple loads need high power inverters and appropriate control techniques. This paper proposes an inverter configuration with buck-boost converter for multiple load induction cooking application with independent control of each load. It uses one half-bridge for each load. For a given dc supply of VDC, one more VDC is derived using buck- boost converter giving 2VDC as the input to each half-bridge inverter. Series resonant loads are connected between the centre point of 2 VDC and each half-bridge. The output voltage across each load is like that of a full-bridge inverter. In the proposed configuration, half of the output power is supplied to each load directly from the source and remaining half of the output power is supplied to each load through buck-boost converter. With buck-boost converter, each half-bridge inverter output power is increased to a full-bridge inverter output power level. Each half-bridge is operated with constant and same switching frequency with asymmetrical duty cycle (ADC) control technique. By ADC, output power of each load is independently controlled. This configuration also offers reduced component count. The proposed inverter configuration is simulated and experimentally verified with two loads. Simulation and experimental results are in good agreement. This configuration can be extended to multiple loads.

Single Inverter Configuration for Simultaneous Dual Frequency Induction Hardening with Independent Control

Induction hardening is used to heat and harden different parts of components with different size and shape. Components with non uniform surface like gears require different frequencies, a low frequency to heat inner core and a high frequency to heat the outer surface. It is desirable to apply these low and high frequency currents simultaneously for proper hardening of gear. This paper proposes a single inverter topology with a load resonant circuit with independent and simultaneous control of low and high frequency currents through the load coil. The load circuit is a combination of two series resonant circuits which operates at the desired low and high frequencies. Asymmetric duty cycle control technique is used to achieve power control.

The Design and Research of Active Clamp Forward Converter Based on IR1150

Nowadays, the development of Power Electronics is very quickly. High frequency switching power supply has been widely used in many fields because of its advantages, such as high efficiency, low volume and low cost etc. this paper focuses on the research of DC-DC transform technology in switching power supply. In the foundation of the traditional forward converter, an active clamp forward converter based on one-cycle control is designed. The control IC is IR1150 based on one cycle control technique. The results show that the converter can effectively eliminate the interference of power ripple and switch error. The control method is simple and reliable. The peripheral circuit is easy to realize.

A Single Cycle Inverter Welding Power Control System

Single cycle control technique is applied in the field of welding power which makes waveform control in the various stages of arc and circuit in the welding process respectively based on the characteristics of the welding process. A new welding power control has been put forward which is able to adjust the grid voltage disturbance in a very short time. We choose dual single-ended forward topology as the main circuit and make flux reset for the transformer in each cycle to ensure that the transformer magnetic saturation dose not occur, meanwhile, controlling the condition of arcing and short circuit respectively to achieve a better welding effect.