DC-DC Chopper Research Articles

DC motor speed control using boost converter DC-DC chopper type based on the PID controller

Abstract The boost converter with PID-based control is designed to be able to control the speed of the DC motor. In particular, the boost converter based on the PID able to produce output from the control process that is more intelligent, efficient and effective in maintaining the stability of the DC motor rotation. From the results, It can shows the difference and effect of output when using only boost converter and when implemented with PID control. The motor control is carried out with different torque conditions. The expected result is controlling the motor speed by the boost converter based on the PID and its performance at the time of starting as well as to changes in the reference speed of rotation and load according to the set point. From the experiment, it was found that the boost converter can increase the voltage according to changes in load torque and PID control can eliminate overshoot on the system and can reach the reference speed quickly, it only takes 1 second. Based on the data analysis that has been conducted, it can be concluded that the boost converter with PID controller functions quite well to regulate the DC motor speed to remain at the reference speed.

Mitigation of voltage sag in a distribution system during start-up of water-pumping motors using superconducting magnetic energy storage: A case study

Voltage sag represents one of the most significant features of power quality in operation of distribution systems. The voltage sag throughout the distribution system caused by simultaneous start-up of water-pumping motors represents a problem, which negatively affects the power quality of the distribution system. The present research work investigates mitigation of voltage sag in a real Egyptian distribution system during simultaneous start-up of many connected water-pumping motors by using superconducting magnetic energy storage (SMES) unit. This calls for a transient analysis of the real distribution system using MATLAB package in order to follow up the temporal variation of the system voltage-profile during motors' start-up. A fuzzy-logic (FL) control strategy of SMES unit is adopted to compose of cascaded control a six-pulse pulse-width modulation (PWM) voltage source converter (VSC) and two-quadrant DC-DC chopper. The proposed fuzzy logic controller (FLC) of SMES unit employs the bus voltage variation and the variation of SMES current as input signals to control the power transfer between the distribution system and SMES. The effectiveness of the proposed FL-controlled SMES unit is validated in a case study of a real distribution feeder named Karot distribution feeder loaded by 16 water-pumps driven by induction motors as well as residential loads. The feeder is part of a distribution system serving the Unified Egyptian Electrical Network. The obtained results indicate that the SMES unit successfully mitigated the voltage sag in Karot distribution feeder due to simultaneous start-up of connected water-pumping motors where the voltage never drops below 0.9 pu.

Genetic PID and Feedforward Controllers for DC-DC Chopper Converter

Wydawnictwo SIGMA-NOT wydaje czasopisma fachowe informujące swoich czytelników o najnowszych osiągnięciach naukowych i nowoczesnych rozwiązaniach technicznych w Polsce i na świecie, popularyzuje problemy techniczne oraz poszerza wiedzę i kulturę techniczną.

Power Generation using Hybrid Energy System for Domestic Purpose

We all are aware that the world is precisely running towards a quest for a substitute energy source. Till today, the maximum power requirement is met with the help of fossil fuels. Anyways the estimates which were made recently have predicted that the usage of the fossil fuels like oil and coal might last only till 2030, and later we will have to switch over to the usage of more efficient sources and emerging technologies. According to current situation the further usage of oil and coal will be replenished and whole world will need to foster for renewable energy source which can satisfy the growing needs of the future generation. For the past few years solar and wind energy have already been trapped and are widely accepted as an alternative source of energy. But in this paper we have planned to concatenate the three outcomes i.e. heat, pressure and sound. Most of the times these three energies are considered as unwanted source of energy and they go unnoticed. With the help of Peltier module, Piezoelectric transducer and sound absorption unit the energies like heat, pressure and noise can be converted into electrical energy respectively. Piezoelectric plate transducer is capable of producing energy using the pressure put on the piezo electric plate. In this paper a footstep piezoelectric plate is used easy to incorporate and even effect cost wise. Peltier module is a thermoelectric device which has the capability of converting the thermal/heat energy into electricity. It primarily works based on the principle of Seeback effect. This device is built using 2 different semiconductor material like p-type and n-type. As the heat emerges and spreads through the material, charge carriers begin to cold side from hot side. The resultant voltage is proportional to the difference in temperature between the layers of the device. As long as there is a difference in temperature the material keeps generating the potential difference. The voltage produced by the entire Peltier module is function of time and the temperature difference. The voltage varies with the change in temperature gradient and time. The sound absorption unit uses sound as an input for producing electric energy, because lot of sound is wasted in our surrounding where in it can used as a source of energy. By using these non-conventional type of energy resources, the generation of power can be achieved with a minimal cost and it will also pave a way to the conservation of the conventional energy source for future needs. This energy thus generated is boosted and stabilized using a DC-DC chopper and later utilized to operate a DC load.

Enhanced Dynamic Behaviour of Grid Connected Wind Farms in Load Participation and Frequency Regulation

The control of grid frequency in power systems due to the penetration of wind turbines is vital to maintaining the stability of power grids, based on recent grid requirements. In this paper, the dynamic behaviour of a wind farm connected to an existing grid is presented. The existing grid is made up of steam turbines, while the wind farm is based on squirrel cage induction generators. An energy capacitor system is used to stabilize the wind farm during periods of wind speed change. Loads with various capacities were connected to the grid to test the robustness of the controllers of the energy capacitor system employed. Furthermore, the effect of varying the time constant of the in-built DC-DC chopper of the energy capacitor system was investigated, considering load participation in the grid. One of the targets of this paper is the stabilization of the grid frequency of the network, despite the load capacity and the nature of the wind speed in the wind farm. The system performance was evaluated using Power System Computer Design and Electromagnetic Transient Including DC (PSCAD/EMTDC). The same conditions of operation were used to investigate the various scenarios considered in this study, to ensure an effective comparison. The natural wind speed employed was the same for all the considered scenarios. The presented results show that small load capacity with a high value low pass filter time constant, provided better response for the grid frequency and the entire variables of the power network.

Integrated DC-AC and AC-DC converter using H-converter for wide range voltage applications

PurposeThis paper aims to propose Hidden Converter (H-Converter) combined with dual port 3Ø inverter for energy storage application to produce wide range of voltage. Some of the application required wide range of voltages, but problem from E-chopper is either boost or buck mode of operations, both modes are not possible. To overcome this drawback, H-Converter is combined with dual port 3Ø inverter controlled by carrier-based pulse width modulation (CB-PWM) technique is added with zero sequence injection.Design/methodology/approachHidden converter is a bidirectional DC-DC chopper used to convert fixed DC to variable DC and vice versa in both buck and boost modes of operations. Dual port inverter is combined with hidden DC-DC converter can produce wide range of voltages.FindingsThe bidirectional DC-AC converter requires less power for processing and consumes less power losses by using modest carrier built- pulse width modulation scheme through proposed zero structure addition.Originality/valueBy using this proposed strategy H-Converter can produce wide range of voltage in both the sides and mostly power is processed in the 3Ø inverter with a one stage conversion with less power loss. As a result, with one stage power conversion has more efficiency because of less power loss. This proposed converter has designed by analysis, and the real time result is tested in an experiment.

Enhancement of DFIG LVRT Capability During Extreme Short-Wind Gust Events Using SMES Technology

Wind energy is one of the premier renewable energy sources that have gained popularity during the last decade. Among the currently available wind energy conversion systems (WECS), doubly fed induction generator-based technology has been widely employed due to its superior advantageous. The key features of the DFIG-based WECS include its ability to capture more wind energy and support the grid with large reactive power during short disturbance events. On the other hand, DFIG is very sensitive to grid faults which affect its fault ride through (FRT) capability. Furthermore, extreme wind gust even for short durations may lead to the violation of the low voltage ride through (LVRT) threshold limits set by worldwide transmission line operators. This situation cannot be mitigated by the turbine blades pitch controller since the response of the pitch mechanical control is much slower than the rapid dynamic change in the wind speed during short duration of wind gust events. While DFIG FRT capability has been discussed in several papers in the literature, not much attention was given to the mitigation of the effects of extreme wind gust of short duration on the DFIG performance. In this paper, the effect of various levels of wind gust on the performance of a DFIG-based wind energy conversion grid-connected system is investigated and mitigated using a new controller for superconducting magnetic energy storage (SMES) unit. A combination of hysteresis current and fuzzy logic controllers is employed to control the voltage source converter and the DC-DC chopper interfacing the SMES coil with the investigated system. Simulation results reveal the effectiveness of the proposed SMES controller that can be easily implemented within existing as well as new WECS installations.

Alleviation of Extremely Power and Voltage Variations Caused by Wind Power and Load Demand Using SMES

Due to the high variations in wind speed and the continuing changes in load power demand (LPD), power and voltage at the point of common coupling (PCC) fluctuate according to the variations of injected wind power generation (WPG) and LPD simultaneously. Superconducting magnetic energy storage (SMES) plays a significant role in alleviating the power/voltage at PCC. This paper shows the impact of SMES in enhancing the performance of interconnected WPG system during high wind gust variations and the changes in LPD. WPG includes squirrel-cage induction generator (SCIG) type with a shunt-connected capacitor for improving the power factor. WPG, SMES and the load are located at PCC. Fuzzy logic control (FLC) is used with the DC-DC chopper to control the power exchange between AC system and SMES. FLC is designed where SMES can absorb/inject real power from/to the grid. On the other hand, reactive power is controlled to adjust the variation of PCC voltage. Two inputs are applied to the FLC; the summation of wind power variation and change of LPD as the first input and the variation of SMES current is the second one to control active power transferred between SMES and AC system. The suggested control approach of SMES is a fast response, as it successfully controlled the PCC voltage, line active and reactive powers during wind gusts and the variations of the load side.

Small-Signal Modeling and Closed-Loop Control of a Parallel–Series/Series Resonant Converter for Wireless Inductive Power Transfer

Usually, the parallel-compensated inductive power transfer (IPT) topology fed by a current-source inverter is controlled through variable switching frequency and fixed 50% duty cycle method. This enables the system to operate at resonance frequency, which drifts due to load and other parameter variations. Owing to this control constraint, the load requirements are fulfilled by adding extra dc-dc chopper at the output. This paper presents a new control technique for a parallel-series/series IPT network, fed from a full-bridge current-source inverter to meet the load demand directly by an inverter. Therefore, the extra chopper stage at the output side of the converter is eliminated. The control goals are achieved through a two-loop control method, where the inner input current loop controls the source current and the outer output current loop meets the load requirements. The detailed steady-state operation, converter design, small-signal modeling, and control are reported, and experimental results obtained from a 1.6-kW lab prototype are included to verify the mathematical analysis.

Proposed circuit design could increase switching efficiency in wind energy grids

Simulations show improved dynamic performance in wind energy grids that use dual parallel DC-DC chopper switching circuitry.

Improving the dynamic performance of grid connected wind farm using new SMES switching technique

Due to the uncertain nature of wind energy, the effective operation of grid connected wind farms is quite a challenge for grid operators. The stipulated grid requirements for frequency and voltage control must be satisfied to avoid the shutdown of grid networks during periods of dynamic grid disturbance. This paper tends to improve the dynamic performance of a grid network consisting of nuclear and thermal turbines that are tied to a wind farm that is made up of fixed speed squirrel cage induction generator wind turbine type. A supermagnetic energy storage (SMES) system is connected to the terminal of the wind farm in order to achieve smoothing of the distorted wind turbine variables so that steady power supply could be maintained during periods of grid disturbance. A new control strategy to improve the performance of the traditional SMES is proposed by integrating a parallel DC-DC chopper in the circuitry of the voltage source converter. The responses of the proposed control strategy for SMES were compared with the traditional SMES scheme during grid disturbance under the same conditions of wind speed. The simulation results in power system computer aided design and electromagnetic transient including the DC platform show the improved performance of the grid variables considering the proposed scheme for SMES.

Enhancing the HVRT and LVRT Capabilities of DFIG-based Wind Turbine in an Islanded Microgrid

Doubly fed induction generator (DFIG) based wind turbines are very sensitive to grid voltage variations. Therefore, low-voltage-ride-through (LVRT) and high-voltage-ride-through (HVRT) capabilities are employed to improve DFIG performance during grid faults and voltage swell events. In this paper, a superconducting magnetic energy storage (SMES) device with a PWM voltage source converter and a DC-DC chopper is proposed to enhance the DFIG LVRT and HVRT capabilities in an islanded microgrid simultaneously. The simulation results demonstrate that the SMES absorbs or releases energy from/to the microgrid during voltage swell events and fault condition respectively and consequently, improves the DFIG performance and enhances the DFIG LVRT and HVRT capabilities. The effectiveness of the proposed method is validated through detailed simulations in PSCAD/EMTDC.

A new controlled superconducting magnetic energy storage for dynamic stabilization of distributed generation in islanding mode of operation

Summary According to IEEE std. 1547, islanding mode is “a condition in which a portion of an Electric Power System (EPS) is energized solely by one or more local EPSs through the associated Point of Common Coupling (PCC) while that portion is electrically separated from the rest of the area EPS”. Therefore, the dynamic instability due to islanding may result in power swing and finally loss of synchronism. Hence, many studies have been done for islanding detection and disconnection of distributed generation (DG) in an EPS. But, these conventional methods eventually lead to the disconnection of the DG units. To improve DG dynamic stability, superconducting magnetic energy storage (SMES) can be used effectively, because SMES have a high-energy density and fast response. This paper proposes a new method to damp the power swing after DG islanding and to maintain synchronism conditions based on SMES. Hence, the disconnection of the DG units is not required. Also, new controllers are developed for SMES including voltage source converter (VSC), and DC-DC chopper. The controller structures of VSC and DC-DC chopper are of PI and fuzzy logic-based type, respectively. Superconducting coil charging is controlled by the DC-DC chopper. SMES sizing is performed, based on power swing equations. Hereupon, dynamic load model is considered. Performance of the proposed method is evaluated by defining 12 scenarios such as strong and weak networks with load changing simulated in PSCAD. Simulation results show that the islanded DG stabilization (IDGS) method has good performance to maintain stability margin in a weak network.

Research on power equalization using a low-loss DC-DC chopper for lithium-ion batteries in electric vehicle

In the near future, electric vehicle is entirely possible to replace traditional cars due to its zero pollution, small power consumption and low noise. Lithium-ion battery, which owns lots of advantages such as lighter and larger capacity and longer life, has been widely equipped in different electric cars all over the world. One disadvantage of this energy storage device is state of charge (SOC) difference among these cells in each series branch. If equalization circuit is not allocated for series-connected batteries, its safety and lifetime are declined due to over-charge or over-discharge happened, unavoidably. In this paper, a novel modularized equalization circuit, based on DC-DC chopper, is proposed to supply zero loss in theory. The proposed circuit works as an equalizer when Lithium-ion battery pack is charging or discharging or standing idle. Theoretical analysis and control method have been finished, respectively. Simulation and small scale experiments are applied to verify its real effect.

A Developed Voltage Control Strategy for Unbalanced Distribution System During Wind Speed Gusts Using SMES

The fast response, high efficiency and long lifetime of superconducting magnetic energy storage (SMES) compared to other energy storage systems make it a preferable selection for energy storage solution for wind power generation. SMES has attracted many researchers to study its potential applications in power systems. This paper discusses a scheme of fuzzy logic controlled SMES to minimize the voltage fluctuations of three-phase unbalanced radial distribution systems connected to wind energy conversion system (WECS) with large scale penetration level of 30% during wind speed gusts. In this paper, wind turbine used is of squirrel cage induction generator (SCIG) with shunt connected capacitor bank for power factor improvement. SMES unit consists of superconducting coil, DC-DC chopper, step down transformer, power conditioning system, and cryostat/vacuum vessel. The control technique is based on fuzzy logic controller (FLC). The studied system is 33-bus three-phase unbalanced radial distribution system. The SMES and WECS were connected to weakest buses in the system, namely Buses18 and 33. The control strategy is discussed in details and the proposed system is evaluated by simulation in MATLAB/SIMULINK package. The simulation results demonstrate the performance of the proposed fuzzy-logic-controlled SMES in mitigating the voltage fluctuations under wind speed gusts.

Transient Stability Improvement Using UPFC-SMES in A Multi Machine Power System

Unified Power Flow Controller (UPFC) is a Voltage sourced converter based Flexible A.C.Transmission (FACTS) controller which has a capability of simultaneously or selectively controlling all the parameters affecting transmission of power. With emphasis on harnessing renewable energy many energy storage technologies are being used. Superconducting magnetic energy storage (SMES) stores energy in magnetic form by means of a D.C. current circulating in a superconducting coil. To exchange power with SMES a power electronic interface is required. Feasibility of interfacing SMES to D.C. link of UPFC has been explored in this paper. A multimachine system with a long transmission line is compensated by UPFC-SMES .A DC-DC chopper modulates power of SMES so as to improve the transient stability of system. Complete simulation has been done using MATLAB/Simulink which shows improvement of first peak, damping of oscillations & improvement in critical clearing time.

定電力負荷とLCフィルタを持つ直流給電系で生じる振動現象の一抑制方法

In a DC power supply system with a constant power load (CPL) and LC filter, the input voltage may oscillate because of the interaction between the output impedance of the LC filter and input negative impedance of the CPL. This paper proposes a control method for the oscillation that uses a bidirectional DC-DC chopper and a power storage capacitor in order to reduce the energy loss for oscillation suppression. In the method, the four variables of voltages and currents in the LC filter and bidirectional DC-DC chopper are feedbacked to suppress the oscillation. To reduce the number of sensors, the minimum order state observer was adopted. The effectiveness of the proposed method was demonstrated in both simulations and experiments.

An Adaptive-controlled Superconducting Magnetic Energy Storage Unit for Stabilizing a Grid-connected Wind Generator

This article introduces an adaptive artificial neural network controlled superconducting magnetic energy storage with the purpose of enhancing the dynamic stability of a wind generator that is connected to the electric grid. The control strategy of the superconducting magnetic energy storage unit depends on the cascaded control scheme of a voltage source converter and a two-quadrant DC-DC chopper using insulated-gate bipolar transistors. The proposed controller is used to control the duty cycle of the DC-DC chopper. The modeling of the system and its control techniques are presented. The effectiveness of the proposed adaptive artificial neural network controlled superconducting magnetic energy storage is then compared with that of a conventional proportional-integral controlled superconducting magnetic energy storage. This study concentrates on symmetrical and unsymmetrical faults. A two-mass drive train model of the wind generator is utilized in the analyses for realistic responses as it has a huge impact on fault analysis. An over-voltage protection scheme is connected across the DC-link capacitor for over-voltage protection. The validity of the proposed control scheme is verified with the simulation results which are performed using the standard PSCAD/EMTDC environment.

Analysis of Variable Speed PFC Chopper Fed BLDC Motor Drive

<p>This paper provides the detailed analysis of the DC-DC chopper fed Brushless DC motor drive used for low-power applications. The various methods used to improve the power quality at the ac mains with lesser number of components are discussed. The most effective method of power quality improvement is also simulated using MATLAB Simulink. Improved method of speed control by controlling the dc link voltage of Voltage Source Inverter is also discussed with reduced switching losses. The continuous and discontinuous modes of operation of the converters are also discussed based on the improvement in power quality. The performance of the most effective solution is simulated in MATLAB Simulink environment and the obtained results are presented.</p>

DC-DC Chopper Excitation Control of WRSG for MPPT in Offshore Wind Farm

Abstract This paper gives an idea of different state of the art of offshore wind farm configurations. One of the configurations uses Wound Rotor Synchronous Generator (WRSG), which is connected to HVDC grid through diode bridge rectifier. Field excitation of the generator is controlled for achieving Maximum Power Point Tracking (MPPT) to have full utilization of wind power. The most important feature of the suggested prototype is its low cost and high efficiency. A working model of this configuration is implemented in hardware using DSPIC and the results are verified.