Abstract: This paper consists of two sections: control and stabilizing method for chaotic behaviour of converter is introduced in first section of this paper for the removal of harmonics caused by the chaotic behaviour in current converter. For this work, a Time- Delayed Feedback Controller (TDFC) control method for stability chaotic behaviour of buck converter for switching courses in currentcontrolmode is presented. This behaviour is demonstrated by presenting a piecewise linear discrete map for this converter and then combining the feedback equation to obtain the overall equation of the converter. A simple time-delay feedback control method is applied to stabilize the Unstable Periodic Orbits (UPOs). In second section the effect of a parallel Metal Oxide Arrester (MOV) on the ferroresonance oscillations of the transformer is studied. It is expected that the arresters generally cause ferroresonance drop out. Simulation has been done on a three phase power transformer with one open phase. Effect of varying input voltage has been studied. The simulation results reveal that connecting the arrester to the transformer poles, exhibits a great mitigating effect on ferroresonant over voltages. Phase plane along with bifurcation diagrams are also presented. Significant effect on the onset of chaos, the range of parameter values that may lead to chaos and magnitude of ferroresonant voltages has been obtained, shown and tabulated.
Due to the long cold start time and the slow dynamics of FC, the transfer control strategy of FC-UPS is different from the traditional UPS. This paper proposes a novel seamless transfer control strategy for the FC-UPS system. During the transition from inverter working mode to FC working mode, the PMU supports the dc-bus voltage to aid FC cold start with no load. After FC ﬁnishes cold start, the PMU is switched to currentcontrolmode to ensure that the FC power increases slowly. During the transition from FC working mode to inverter working mode, the ac/dc converter maintains the dc-bus voltage and the dc/dc operates in currentcontrolmode to ensure that the FC power decreases slowly. The design of the SC energy storage is also analyzed. The experimental results show that the proposed control strategy not only guarantees the uninterruptible load voltage, but also protects FC against power demands beyond its allowable bandwidth during the transition.
Abstract In islanding Micro-Grids (MGs), distributed generation units are in charge of controlling voltage, frequency, and current of the grid on their own without any assistance from the main grid. Therefore, it is of utmost importance to select and design a controller that is robust against disturbances and load variations. In this study, a new sliding mode controller with a rotating reference voltage algorithm is proposed which improves the load sharing between distributed generators (DGs) in an islanded mode MG. In the proposed algorithm, the amplitude of the reference voltage signal of the controller is adaptively modified to improve the performance and convergence rate of the controller. As a case study, the proposed strategy is studied based on the assumption that there are three DGs in the grid. One of the DGs is in charge of regulating voltage and frequency based on a reference signals, and the two other DGs are responsible for load sharing and loads currentcontrolmode. The MG under study consists of three low voltage distributed generation units operating in parallel mode. In order to have a realistic case study, it is assumed that the MG consists of different types of loads such as resistive, inductive and nonlinear loads. Extensive simulations carried out in MATLAB environment indicate that the proposed framework is able to provide more desirable total harmonic distortion (THD), lower steady state error, and faster response compared with classic sliding mode controllers.
A State of charge algorithm is used to identify the SOC of the battery pack. In the pre-charging mode and constant current charging mode, the currentcontrolmode is activated. SOC algorithm will generate different reference current to regulate the charging current to be 0.1C and 1C, respectively. According to the SOC algorithm the duty ratio is calculated and also determines whether the battery should be operated in constant currentcontrolmode or constant voltage controlmode. This algorithm will also provide the reference value for current or voltage (Iref or Vref) which is then compared with actual value and provides specified duty ratio. Based upon this duty ratio a PWM pulse is generated and this is compared with PWM pulse generated by comparing the constant voltage and the actual output voltage. This type of comparison will improve the lifetime of a battery when compared to theconventional plug-in electric vehicle battery charger technique.
The proposed schemes show voltage controlled distribution STATCOM compensator advantages over the traditional voltage controlled DSTATCOM. The scheme generates a new algorithm for voltage controlled mode operation of distribution STATCOM compensator to generate reference voltage. The proposed schemes ensure the unity power factor (1.0 p.u) to be achieved at the load terminal during nominal operation which can’t be done in traditional method. The DSTATCOM injects lower current and reduces loses in voltage source inverter and feeder, further the capacity of compensator to mitigate the voltage sag is increased. The DSTATCOM can switch between currentcontrolmode (CCM) and voltage controlmode (VCM) mode any time needed using fuzzy which is not possible in the traditional method. The system also apt in tackling power quality problems by providing power factor correction, voltage regulation and can free the system from harmonics by eliminating them and maintain load balance. The experimental results along with simulations are demonstrated the system is efficient enough.
Robustness in nonlinear control can be effectively accomplished using sliding modecontrol (SMC)  . But it has been observed that there is lot of chattering in the control effort, which is undesirable . There are several methods to eliminate chattering from the control input. An attempt has been made in this paper to eliminate the chattering in control input of SMC by replacing the discontinuous signum function by saturation function and hyperbolic tangent function. Better performance and robustness is achieved in case of sliding modecontrol with its variants as compared to classic PID controller under the presence of uncertainties
Abstract: This paper presents a configuration of dual output single phase current source inverter with 6 switches for microgrid applications. The inverter is capable of delivering power to two independent set of loads of equal voltages or different voltages at the load end. The control strategy is based on Integral Sliding ModeControl (ISMC). The remote monitoring of the inverter is performed with cyber infrastructure. The cyber physical test bench is developed based on Reconfigurable I/O processor (NI MyRIO-1900) for control and monitoring of the inverter. The inverter prototype is tested in cyber physical test bench in laboratory conditions. The performance of the inverter is analyzed and monitored through the remote system. Also, the inverter is analyzed with different voltage conditions.
From the non-isolated LED Boost-Buck converter circuit diagram, it can be seen that the converter consists of rec- tifier bridge, boost circuit, buck circuit, driving signal and the load. And the Boost-Buck converter uses ca- pacitor as energy transfer component between the first and post stage rather than the inductor mostly used in other conventional converters. It can be known from the analysis that the Boost-Buck converter features fast tran- sient response and excellent frequency response, allow- ing highly stable feedback regulation to be achieved with simple circuit [15-17]. Two inductors at both input and output side are working in continuous current conduction mode. The inductor ripple current is low and continuous, which can greatly reduce the requirements of input and output filter capacitor. All switch nodes in the circuit are isolated between the two inductors, input and output nodes have no effect on each other, which would make the radiation EMI (Electro Magnetic Interference) from the converter minimized. The operational principles are described and discussed in the next sections.
Sensing devices are a boon in today's technology, from being a simple thermometer to Electro-Mechanical industry. Various sensing devices are being made using microelectronics. A special branch knows as MEMS is working towards the development of these devices. Interfacing digital circuits with the sensor devices becomes simpler if the sensor devices are of digital nature. Due to the on/off nature of digital signals, various electrical components like switches, relays, & digital encoders are interfaced with easiness along with the gate circuits. It is requisite to electronically interpret analog signals into digital capacities, since when the devices of analog nature are intricate, interfacing becomes a complexity. The vice versa conversion of analog to digital is equally needed in a circuit implementing an ADC.  An Analog to Digital Converter takes analog electrical signal for example voltage or current as input and produces a binary digit output. A Digital to Analog Converter, on the contrary, takes an input of binary digit and gives an analog current or voltage as output. Most of the times used together in digital control systems to offer whole interface with analog sensors and output devices for control systems for example those used in automotive engine controls. For example, A-to-D conversion in radio frequency receivers, implant exceptional demands on the converter, and a style in receiver proposal have been to move the digitization nearer to the receiving antenna. 2.1. Process of Conversion from Analog to Digital Signals The process of translating various naturally happening signals like pressure, temperature, voltage, current, distance, or light magnitude into a digital representation of that signal is carried out by Analog-to-Digital converters (ADC).  Talking of data processing devices, wherein the input has to be analog and for interfacing it with computers for reading, understanding and manipulating the data, we need digital signals. Hence to convert the signals from analog to the digital an ADC is required for such processing devices. Primary cause that digital signals are preferred over analog signals is that these signals proliferate more effectively than analog signals, broadly because digital impulses are properly-defined and structured, are simpler for electronic circuits to differentiate from noise, which is haywire.
Power factor correction (PFC) converters are used to avoid power quality problems at the AC mains and to meet the prescribed guidelines of IEC 61000-3-2. The sensing requirement of this PFC converter plays major role in deciding the cost of overall system. The required number of sensors for a PFC converter is primarily decided by its mode of operation of the PFC converter. Continuous inductor currentmode (CICM) and discontinuous inductor currentmode (DICM) are two modes of operation of the PFC converter. In CICM, or continuous conduction mode (CCM), the current in inductor remains continuous in a switching period, whereas the current becomes discontinuous in a switching period for a PFC converter operating in DICM. The PFC converter operating in CICM uses a current multiplier approach for voltage control and power factor correction. It has lower current stress on the PFC converter switch but requires three sensors for its operation. However, a single voltage sensor is used for a PFC converter operating in DICM using voltage follower approach, but at the cost of high current stress on the PFC converter switches. Therefore, this mode of operation is suited for low power applications.
Switched-mode power supplies employ either variable switch duty cycle or variable switching frequency (occasionally both) associated with feedback circuitry to provide the required output voltage and output current. Today it is possible to design variety of pfc circuit with different modes of operation. There exist two mode of operation discontinuous and continuous. Here didode bridge rectifier act as non linear load and because of non linear load there is distortion in input current. Buck-boost converter in discontinuous inductor currentmode is studied and simulated. The peak currentcontrol technique for continuous conduction mode is studied and simulated in MATLAB beacause it allows low THD input current and unity power factor. The MATlab/Simulink results of peak currentcontrol technique comply with IEEE 519-1992 standard.
The previous sections discussed about the software structure of the system. The different modules of the code designed to perform dedicated operations were described. The control loop operations like FDPOL voltage control, FBCM battery charge control, and MPPT control and path selection were described. As is evident from the past discussions, intelligent power processing systems like CubeSat EPS pose a significant challenge when it comes to the software design. Hence, it is important that the code be profiled and optimized for speed and memory usage. A code that executes faster will result in an increase in the sampling frequency which enhances the transient performance. Also, a faster code would help in increasing the functionality as more functions can be integrated without compromising the system performance. The main control loop runs every 100µs which means that the voltage/current loops are and run and the duty cycle is updated every 100 µs. In every cycle, the voltage and currents are sampled four times and the values are averaged before being used to calculate the error. Figure 49 shows the relationship between the various intervals. The pink trace shows the switching frequency while the yellow and blue traces show the sampling and update frequencies respectively.
An additional pad to access the internode of the cascode was added to all multi-finger cascode devices, enabling the potential at the internode to be monitored during the switching measurements (inset in Fig. 3). Devices exhibit similar DC characteristic as shown in the on-wafer gate transfer measurement results in Fig. 3. Output currents > 1 A and threshold voltages of the E-mode part (V th-E ) > 0 V were
In a general power system, the generated electrical runs to customers through the transmission and distribution network. High voltage is used for electric power transmission to reduce the energy lost in the resistance of the wires. For a given quantity of power transmitted, doubling the voltage will deliver the same power at only half the current. Since the power lost as heat in the wires is proportional to the square of the current for a given conductor size, but does not depend on the voltage, doubling the voltage reduces the line losses per unit of electrical power delivered by a factor of 4. While power lost in transmission can also be reduced by increasing the conductor size, larger conductors are heavier and more expensive. High voltage cannot readily be used for lighting or motors, so transmission-level voltages must be reduced for end-use equipment. There are three types of DC transmission lines. They are mono polar, bi polar and homopolar.
Power factor has a high impact on power system industries. A load with low power factor draws more current than a load with high power factor for the same amount of useful power transferred. The high current increases the energy lost in the distribution system and requires large equipment to dissipate wasted energy. Electrical utilities usually charge high cost to industrial/commercial consumers where there is a low power factor. With the development of technology in power semiconductors devices, the rate of using power electronics system has expanded to new and wide applications that include residential, commercial, aerospace and other systems. In the non- linear systems, loads are the main sources of harmonics and it affects efficiency. The current dawn by the power electronics interface from the line is distorted resulting in a high total harmonic distortion (THD) and low power factor (PF).This creates adverse effects on the power system that include increased magnitude of neutral current in a three phase system, over heating of transformers and induction motor. Hence, there is a continuous need for both the improvement of power factor and reduction of line current harmonics. This work is to implement a boost converter with average currentmodecontrol technique for the improvement of the power factor and reduction of total harmonics distortion. The boost converter can perform this type of active power factor correction in many discontinuous or continuous modes. Average current measurement provides the input current with high degree of accuracy. Average currentmodecontrol technique works wells even when the mode boundary is crossed into the discontinuous mode at low current levels. Open and closed loop boost converter using average currentmodecontrol has been simulated by power simulation (PSIM) software. Hence the waveforms of the input current shows the improvement of PF and reduction of THD.
The series compensator known as DVR is used to inject a voltage in series with the terminal voltage. The sag and swell in terminal voltages are compensated by controlling the DVR and the proposed algorithm inherently provides a self-supporting dc bus for the DVR. Three-phase reference supply currents (isa*, isb*,isc*) are derived using the sensed load voltages (vla, vlb, vlc), terminal voltages (vta, vtb, vtc) and dc bus voltage (vdc) of the DVR as feedback signals. The synchronous reference frame theory based method is used to obtain the direct axis (id) and quadrature axis (iq) components of the load current. The load currents in the three- phases are converted into the d-q-0 frame using the Park’s transformation as,
Abstract:- Analogue design has been historically viewed both in voltage-mode and current-mode dominated form of signal processing. In literature wide variety of techniques and circuits are available for the design of different current-mode signal processing circuits suitable for VLSI implementation. In this paper we present the major current-mode building blocks using complementary CMOS current-mirror pairs such as current adders and current integrators (lossy and lossless). These building blocks form the basic constitutional blocks for the implementation of second-order continuous-time current-mode active filters. All the proposed circuits presented in this paper were tested in SPICE using 0.5µm CMOS process parameters provided by MOSIS (Agilent) and the results thus obtained were in accordance with the theoretical values.
DC motors are given preference in many industrial applications by reason of some advantages provided by their working characteristics. DC motors are widely used in systems with high control requirements. Thus, rolling mills, double-hulled tankers, and high-precision digital tools can be mentioned as examples of such systems. Frequently, dc- to-dc power converters are used as dc motor drives, which apply the required voltage to the dc motor in accordance with the demanded task represented by the desired angular velocity profile or angular position reference trajectory.
ABSTRACT: With rapid development in power semiconductor devices, the usage of power electronic systems has expanded to new and wide application range that include residential, commercial, aerospace and traction system and SMPS. The current drawn by power semi converter devices from the line is distorted resulting in a high Total Harmonic Distortion (THD) and low Power Factor (PF). Hence, there is a continuous need for power factor improvement and reduction of line current harmonics. In this paper we have done the comparative analysis of various circuits for Power Factor Correction using active PFC circuits. It is based on an optimized power sharing strategy to improve the current quality and at the same time to reduce the switching losses. Voltage modecontrol is used for switching operation of Buck Converter and Average currentmodecontrol is used for switching operation of Boost and Dual Boost Converter based PFC methods. Key words: Power factor, Buck converter, Boost converter, Dual Boost converter, Voltage modecontrol, Average Currentmodecontrol. There are multiple solutions to make line current is nearly sinusoidal. This paper also presents the technique for single phase power factor correction of non-linear loads using an active power filter.
Abstract. High voltage direct current (HVDC) transmission is a better prospect choice compared to high voltage AC transmission. The HVDC is able to apply higher voltage level and without any reactive power losses. By supporting power electronic technology, the HVDC is simpler and cheaper to be realized. So, the problem in the HVDC system is how to control power flow in rectifier converter device effectively. In this research, regulating of firing delay angle is proposed by ANFIS-based controller (ANC) in 12-pulse rectifier. The ANC is applied because computation of the ANC is more effective than Mamdani fuzzy controller computation. The ANC is trained by data-learning in off-line mode. In normal operation, the maximum transmitted power by the HVDC is on the value of 1.0 pu with voltage and current DC at 1.0 pu when the firing delay angle at 26 o . Also, the ANC is able to compensate temporary short-circuit fault.