Performance Of DC Research Articles

Switching position-torque control system for increasing servo PMDC positioning precision in presence of intense external disturbance loading

The overall performance of servo Permanent Magnet DC (PMDC) machines can be gravely undermined when the machine is prone to strong external disturbances and uncertainty in modeling parameters. Additionally, this effect will be compounded if the PMDC machine is expected to track a low-frequency desired trajectory. The main cause of this phenomenon lies in the third-order differential relationship between control voltage and position and this will inevitably result in a slow convergence of the tracking error to zero. On the other hand, the relationship between PMDC torque and control voltage is of first-order which, from a control point of view, can bear the meaning of the presence of the possibility of a faster response for a torque tracking process. In this study, primarily, a discussion is held on the position control algorithms of DC motors that illustrate robustness against external disturbance. The studied controllers have been compared based on their structure (single loop or cascade structures) and consequently, with respect to their shortcomings and advantages, a Discrete-Time Sliding Mode Control (DTSMC)-based tracking control algorithm named as Position-Braking Tracking Control (PBTC) is introduced in which the servo PMDC is controlled in position tracking mode when motoring/reverse motoring property is expected. Similarly, the PMDC is controlled in torque tracking mode when braking/reverse braking property is announced to be required. Activation and the necessity of position or torque tracking is determined by the execution of a simple analysis on the position and torque tracking errors. The proposed DTSMC-based PBTC system is applied to an industrial servo application and the performance improvements are demonstrated. Obtained results indicate that for low-frequency desired position trajectories, transient response of PBTC is more precise relative to single mode DTSMC-based position tracking control.

Design of Experimental Device for Electrical Performance of Mine DC Stabilized Power Supply

In order to improve the testing method of the electrical performance of the mine-used DC stabilized power supply, this paper designed a test device for the electrical performance of the mine-used DC stabilized power supply based on STM32F407VET6 single chip microcomputer. The device is mainly composed of AC power output, DC power input, analog load, operation control and other units. It can achieve AC0∼1254V AC voltage output underground and the output voltage deviation value, source effect, load effect, and overload of the mine DC stabilized power supply. The current protection value and short-circuit current value are tested and displayed on the display of the industrial computer.

Influence of SiC hetero-polytype barriers on the performance of IMPATT terahertz diodes

The SiC hetero-polytypes with perfect interfaces and no diffusion pollution are adopted to innovatively design the impact ionization avalanche transit-time (IMPATT) diodes. The performance of DC, large-signal and noise of the proposed diodes operating at the atmospheric low-loss window frequency 0.85 THz are estimated via numerically solving the fundamental device equations with and without quantum correction incorporated the tunnel and density-gradient of carriers. The influence from SiC hetero-polytype barriers and material properties on the performance of IMPATT diodes is analyzed. The advantages in power, efficiency and noise generating in the diodes of 4H/6H–SiC hetero-polytypes can be due to high critical breakdown electric field strength and weak ionizing in 4H–SiC and 6H–SiC. However, small power and heavy noise emerging from the devices of 3C/4H–SiC and 3C/6H–SiC hetero-polytypes can be owing to low critical breakdown electric field strength and strong ionizing in 3C–SiC. The noise electric field peaks arising from the strong ionizing layers while deviating from the interfaces in hetero-polytypes are illustrated. The evident quantum effect on the diodes without 3C–SiC while the slight effect on the devices included 3C–SiC are attributed to low-barriers embedded in the former diodes while high-barriers involved in the latter devices, respectively. • The SiC hetero-polytypes are employed to design the impact ionization avalanche transit-time diodes (IMPATTDs). • The 4H/6H-SiC hetero-polytype IMPATTDs imply advantages in power, efficiency and noise due to weak ionizing in materials. • The noise electric field peaks arise from the strong ionizing layers while deviate from the in hetero-interfaces. • The IMPATTDs with 3C/4H-SiC and 3C/6H-SiC hetero-polytype high-barriers encounter weak quantum effect.

A non‐isolated single‐input dual‐output boost DC–DC converter

A new non-isolated single-input dual-output boost DC–DC converter is introduced in this paper. The motivation of the work is that in various applications such as some multilevel converters, it is required to provide multiple dc sources that are not required to be isolated. In the proposed structure, the output ports of the converter can provide different values of power and still balance the output voltage. Even, if required, the output voltages can be set to different values. From practical point of view, the proposed topology uses minimum number of power-electronic switches (two switches for two outputs) which have common ground making their drive circuit simple and easy to implement. The state-space modelling of the proposed converter is presented, then, the model is used to design the passive elements. Moreover, the proposed converter is compared with the relevant converters. In order to verify the performance of the proposed DC–DC converter, a prototype of the converter has been implemented and the results are presented.

Matrix Converter Supported by Hybrid Vehicle System with Perturb and Observe Algorithm for V2G Operation

This paper proposes the application of matrix converter in supplying power from vehicle to grid (V2G) and grid to vehicle. Single phase matrix converter with four switches acting as DC to DC converter in bi-directional operation is proposed. The performance of DC to DC converter adopted for V2G operation is also applied with matrix converter operation. The DC bus is supported by hybrid power system. It comprises of solar and wind energy. Perturb and observe controller algorithm is adopted for power tracking of hybrid system. The charging systems of the batteries are connected by the service provider while the vehicles are parked and the battery also supports the service provider when any interruption occurs, thus a bi-directional power transfer is achieved. The results obtained here illustrate the better power transfer from the hybrid system to grid and grid to vehicles battery.

A Direct Current Control Scheme With Compensation Operation and Circuit-Parameter Estimation for Full-Bridge DC–DC Converter

To boost the dynamic performance of the full-bridge (FB) dc–dc converter, some model-based controls have been recently proposed in the literature. However, in terms of dynamic performance, these methods have failed to reveal the potential of this converter since the inherent relationship among the duty ratio, the input voltage, the output voltage, and the load resistor is not adopted in the controller, and the dynamic performances are still relayed on the fuzzy adjustment based on the disturbances of output voltage as the single-voltage-loop control method. In this article, based on this inherent characteristic of the FB dc–dc converter, an accurate transferred current modulation method is presented first. Based on this modulation method, a simple direct current control (DCC) scheme is proposed for a fast dynamic response with the feedback values of input voltage and load current. Moreover, the model uncertainties such as the power losses and control delay may influence the control performance. Therefore, a compensation operation is also presented to reduce the impact caused by these uncertainties to ensure the dynamic performance of the proposed strategy. In addition, since the circuit parameters including the leakage inductance and the output capacitor should be employed to implement the proposed DCC strategy with compensation operation, inaccurate circuit parameters may influence the performance of these proposed strategies. Therefore, the circuit-parameter estimation methods for these two circuit parameters are also proposed to ensure the dynamic performance of the FB dc–dc converter. Finally, the simulation and experiment results have verified the correctness and effectiveness of the proposed DCC strategy.

Torque ripple suppression of brushless DC motor drives using an alternating two‐phase and three‐phase conduction mode

Commutation torque ripple is an important factor affecting the performance of brushless DC (BLDC) motor drives. In order to suppress this torque ripple, an alternating conduction control strategy between the two-phase and three-phase conduction mode has been proposed in this study. During the non-commutation periods, the conventional two-phase conduction mode is selected to drive the BLDC motor. While during the commutation period, the commutation torque ripple is reduced by employing an alternating two-phase and three-phase conduction mode. By calculating the duty cycle of the three-phase conduction mode, which indicates whether the rate of change in current in the incoming and outgoing phase is equal during the commutation interval, the commutation torque ripple is effectively reduced, while the current in the non-commutated phase is maintained constant. Simulation and experimental results show that the proposed method can suppress the commutation torque ripple efficiently, particularly at high rotational speeds of the motor.

General High-Frequency-Link Analysis and Application of Dual Active Bridge Converters

High-frequency-link (HFL) electrical quantities, including high-frequency voltages, currents, and instantaneous power, are closely related to the performance of dc–dc converters. However, HFL electrical quantities are usually square, triangular, or trapezoidal waves and conventional indicators like apparent power or power factor are with vague physical meaning. This article gives a general HFL analysis to guide the optimization of dual active bridge converters (DAB). Novel indicators are proposed to describe the instantaneous power characteristic, which show better accuracy and reliability than the conventional indicators. Optimization objective construction method and hybrid optimization algorithm are proposed to calculate the optimal control coordinate, and the efficiency of DAB is enhanced for most of the operation points. Besides, the novel indicators and optimization objective are also good at the estimation of efficiency. Finally, experimental results verified the validity of the HFL analysis.

High step-up three-level DC–DC converter with three-winding coupled-inductor

Due to the wide adoption of photovoltaic power generation, non-isolated high step-up DC–DC converters are becoming more and more popular. Among these converters, the switched/coupled-inductor-based converter is more attractive due to the fact that it has fewer power devices and a high efficiency. This paper presents a three-level high step-up DC–DC topology with a three-winding coupled-inductor. When compared with a conventional switched/coupled-inductor-based converter, a higher efficiency can be achieved, owing to low voltage stresses devices, fewer semiconductors in the power loop, lower current stresses, and ZCS of the main switches. The operating principle of the proposed topology is analyzed in detail via equivalent circuits, where a theoretical analysis is carried out using state space modelling. Experimental results obtained on a 24–300 V, 360 W lab prototype have verified the excellent performance of the proposed DC–DC converter.

General Closed-Form ZVS Analysis of Dual-Bridge Series Resonant DC–DC Converters

Switching behavior analysis is an indispensable step for evaluating the steady-state performance of a bidirectional dc–dc converter and a prerequisite for soft-switching modulation design. For dual-bridge series resonant dc–dc converters (DBSRCs), the commonly used fundamental harmonic approximation (FHA) does not usually provide predictions accurate enough for reliable analysis and design. This paper discloses the exact closed-form solution for the zero-voltage switching (ZVS) operation conditions of DBSRCs for the most general case, in which all modulation quantities—i.e., phase shift, duty cycles, and switching frequency—are included. The proposed approach relies on a geometrical analysis of the converter state-plane trajectory, and allows us to analytically predict the ZVS or hard-switching state of any switch and for any given converter operating point. By inherently capturing the effects of all tank harmonics, the model disclosed in this paper shows higher accuracy than the conventional FHA-based approach, and translates into a practical tool for ZVS prediction and optimization at the converter design stage. Based on the derived analytical results, switching behavior of DBSRCs with minimum rms current trajectory (MCT) modulation is investigated, and an effective design choice of resonant-to-switching frequency ratio is presented, which contributes to reduced switching losses and enhanced efficiency. Furthermore, a variable frequency modulation scheme is formulated, achieving ZVS operation of all transistors over a wide input/output voltage range and efficiency improvement versus MCT technique. The analysis and conclusions are validated via extensive experimental tests on a 700 W DBSRC prototype.

DC TO DC CONVERTERS AND ITS APPLICATION FOR RAILWAY SYSTEM- A REVIEW

In modern technologically advanced world, power electronic based converters are extensively used. Among them DC to DC converters are majorly used in transportation system because of its increased efficiency and regenerative system. The railway traction system is eco-friendly, pollution free and largely used transportation system in the world. A review of different types of DC-DC converter, isolated, nonisolated and its recent application in railway traction system is presented here. This paper also covers its key features such as high voltage conversion ratio, ripple factor, galvanic isolation and efficiency performance of DC to DC converters.

Layout optimization of planar inductors for high-efficiency integrated power converters

The performance of dc–dc power converters is critically dependent on the inductors at their core. Planar spiral inductors are compact constructions that can be scaled and integrated without the limitations of traditional wire-wound devices. Therefore, they are increasingly employed to meet the needs of modern low-power applications, especially where size, weight and manufacturing costs are deciding factors. As a planar inductor is designed to fit the parameters of an application, it is paramount to take into account the associated parasitic effects that have an impact on the converter performance. This paper analyzes how the conversion efficiency of boost and buck integrated power converters depends on the parasitics elements of planar inductors, and how it can be improved by optimizing the inductor layout. In particular, the paper provides the guidelines for maximizing the time constant of the inductor by considering the different geometrical features that define the inductor shape. The trade-offs that maximize the inductance time constant for different shapes are introduced, and an algorithm is developed to optimize the performance with no area overhead. Finally, three boost converters are designed, simulated, and compared in a 65-nm CMOS technology to demonstrate the validity of the proposed approach, and the corresponding conversion efficiency improvement is assessed.

Performance Analysis of Modular Forward Converter in Input Parallel Output Series (IPOS) Architecture Using PI and Fuzzy Logic Controller

This paper investigates the performance of modular dc–dc forward converter in Input Parallel Output Series (IPOS) configuration which is controlled by an effective controller. This IPOS topology facilitates the converter to have high output voltage gain. The role of controller is crucial in ensuring the power sharing between the converters. Fuzzy controller, known for its versatility, is employed in this research work. The fuzzy controller feeds appropriate pulse width modulated control signals for appropriate input and load regulation. The performance of the fuzzy controller is analyzed by comparing it with proportional integral controller and a advanced neural network controller. The proposed IPOS system has been analyzed using MATLAB/Simulink environment and hardware prototype. The simulation and hardware results reveal that the suggested topology with fuzzy controller is very effective compared to its counterparts.

Ripple base signal flow graph modelling of DC–DC switching converters

A new ripple base signal flow graph (R-SFG) modelling method was proposed to accurately model and analyse a family of switching DC–DC converter. The performance of some DC–DC converters such as single-inductor multi-output converters is dependent on inductor current ripples. This makes the conventional modelling methods cannot fully predict the overall behaviour of converter. From this family and in this study, a single-inductor dual-output (SIDO) boost/boost converter has been modelled based on proposed R-SFG method. The simplicity and systematic procedure presented in this work showed that the R-SFG could be a good alternative for modelling switching converter with complicated structures and with high inductor current ripple. In the new R-SFG method, the effects of inductor current ripple have been considered to develop the conventional signal flow graph modelling method. In this work, a comparative study between two modelling methods has been carried out in a SIDO converter. A step-by-step direct mathematical manipulation was used to calculate the DC–DC transfer function of SIDO converter. The experimental results were included to show the validity of the obtained models. The experimental results showed that the maximum R-SFG modelling error was about 5% over the wide range of inductor current ripple.

Performance Analysis of Brush Less DC Motor Drive Using Fractional Order Controller with PSO Algorithm

Background: This paper investigates the detailed study on the performance of Brushless DC (BLDC) motors with sudden application of loads, by using different control techniques. The increasing trend of usage of accurate control, high torque, low noise and higher efficiency for Electric Vehicles has appealed the attention Researcher in BLDC motors. So, BLDC motors can act a substitute for the conventional motors like Switched Reluctance motors, Induction Motors etc. Methods: A Fractional Order Propositional-Integral Derivative (FOPID) controller has been proposed in this paper. The parameters FOPID controller is tuned with Particle Swarm (PSO) algorithm based on Integral Absolute Time Error (IATE) rule. A comparative analysis has been carried out in this paper by simulating the BLDC motor in MATLAB/Simulink and conducting experimental setup in the laboratory. Results: The results reveal that the performance of FOPID controller is better regarding settling time, steady state error and ripple factor in the speed response with sudden load application. Conclusion: In reference to the analysis, it can be summarized that the best tuned Fractional Order PID can perform better than the PID. The digital controller isimplemented using ccs-studio and tested in the DSPms320f28335 board.

Effects of frequency and timing offsets in DCT-based multiple access system for VLC

Abstract Visible light communication (VLC) has gained a significant momentum in the recent times due to its distinctive characteristics of imparting concurrent ‘illumination’ and ‘communication’ by exploiting sustainable and energy-efficient opto-electronic devices like light emitting diodes (LEDs). Consequently, by utilizing the already installed LED lighting fixtures a small scale cellular communication network can be created within an indoor environment imparting economic and ubiquitous data transmission services to multitude of roaming mobile stations within the proximity of LEDs. Therefore, it is vital to address the detrimental aspects like carrier frequency offset (CFO) and symbol time offset (STO) which emanates predominantly in an uplink scenario. This paper evaluates the performance of DC offset optical fast orthogonal frequency division multiple access (DCO-FOFDMA) system in the presence of both CFO and STO and accomplishes a thorough mathematical analysis emphasizing the different interferences like inter carrier (ICI) and multi user interferences (MUI) emanating due to different timing disparities and frequency discrepancies. The simulation results evidences that, with the increase in sensitivity of CFO and timing misalignments, the system performance drastically deteriorates thereby hindering the detection capability of multiple users operating at the same time. In order to estimate the STO, synchronization algorithms like Maximum Likelihood (ML) and Classen are imposed to the developed system model. Additionally, Cramer Rao Lower Bound (CRLB) is derived for the estimation of CFO and STO.

Improved dynamic performance of dual active bridge dc–dc converters using MPC scheme

Dynamic performance is a key focus of power conversion systems for facing with input and output step-change and disturbance cases. To improve dynamic characteristic of dual-active-bridge dc-dc converters, this study proposes a non-linear model predictive control (MPC) scheme with phase-shift ratio compensation to face with the following extreme conditions: start-up or step change of load resistance, input voltage, and the desired output voltage. Furthermore, in view of the idea of direct current control, MPC scheme using fewer sensors is proposed, which greatly increases the flexibility of control system and reduce the cost. Compared to traditional voltage closed-loop (TVCL) control and model-based phase shift (MPS) control, the salient features of the proposed MPC can be summarised as excellent dynamic performance, weak parameter sensitiveness, in addition, it is also available and effective when the load current sensor is not used. Finally, three control schemes consisting of TVCL, MPS, and the proposed MPC scheme are compared and tested in a scale-down experimental prototype. The above excellent performance of the proposed MPC scheme has been verified by experimental results.

An improved dynamic performance of bidirectional SEPIC-Zeta converter based battery energy storage system using adaptive sliding mode control technique

An improved dynamic performance of DC–DC bidirectional SEPIC-Zeta converter based battery energy storage system (BESS) has been achieved using adaptive sliding mode control (SMC) technique. The micro-grid concept is gaining importance for integrating various nonconventional energy sources throughout the world. Nowadays, both DC and AC micro-grid systems are employing BESS for getting various advantages such as minimization of power fluctuations, excess or emergency power support etc. In this application, controlled charging and discharging operation of the concerned battery bank is extremely needed. In this scenario, DC to DC bidirectional converter such as combined SEPIC-Zeta converter is considered to facilitate dynamic charging and discharging operation of the concerned battery. Conventional proportional-integral-derivative (PID) controller based control strategy for the bidirectional converter can not always meet the dynamic performance requirements under charging and discharging operation cycles of the battery. Therefore, adaptive SMC action has been proposed to improve both transient and steady state behavior of the BESS. In addition to this, the proposed model can be operated satisfactorily under changed operating condition. The proposed concept is validated via various simulation studies using MATLAB-SIMULINK software. The experimental study is also performed on a prototype of the BESS to validate adaptive SMC case.

Analytical Modeling and Implementation of a Coaxially Wound Transformer With Integrated Filter Inductance for Isolated Soft-Switching DC–DC Converters

In this paper, we propose an approach for integrating a series filter inductance in a coaxially wound transformer (CWT) as a potential alternative to conventional solenoidally wound transformers (SWT) for high-power isolated soft-switching dc–dc converters. The critical elements that determine the size and the performance of soft-switching dc–dc converters are the isolation transformer and the filter elements. While conventional SWTs using a stray magnetic field as a filter inductance often suffer from a considerably increased loss, heat congestion, and electromagnetic interference, a CWT is rarely affected by high frequency and fringing effects. The desired properties are still valid while the required filter inductance is fully integrated with an isolation transformer using the proposed method. In addition, the evenly distributed magnetic fields in a concentric geometry enable accurate electrical and mechanical analysis and a specific application-oriented design. In this paper, the operating principles, design procedure, and loss modeling of a CWT with an integrated filter inductance are introduced. Its functionality and suitability for high-frequency applications were proven by theoretical analysis and experiments. A prototype transformer with an integrated inductance 4 mH was facilitated and evaluated in a 15 kV-SiC mosfet -based 6 k–400 Vdc stage for a solid-state transformer of up to 6.5 kW at a switching frequency of 20 kHz.

Performance of Brushless DC Drive with Single Current Sensor Fed from PV with High Voltage-Gain DC-DC Converter

This paper presents the performance of Brushless DC (BLDC) Motor drive with only one positioning sensor instead of three conventional sensors. The three sensor units are replaced with a single stator current sensor unit in DC bus which further reduces the cost increasing the reliability of the drive system. Using a single sensor in stator requires minimum electronic equipment for the purpose of measurement process. This paper evolves the BLDC motor drive fed from PV system. A high voltage-gain DC-DC converter is presented in this paper to step-up the voltage from PV system. The appropriateness of PV fed BLDC motor drive is verified for variable increamental speed with fixed torque and variable decremental speed with fixed torque operating conditions. BLDC motor drive performance is also performed for variable torque with fixed peed working condition. The proposed system and results are developed using MATLAB/SIMULINK software.