Wave-shaping Circuit Research Articles

Development of Alternating Current (AC) Line Monitoring Device for Power System Management

This work presents a study of the effect of imbalance between the supply of and demand of power from the National grid on electrical appliances. In the study, an alternating current (ac) line monitoring device was developed using arduino microcontroller to carry out the investigation. The device is a single system capable of measuring both the main frequency and nominal voltage of electricity supply. The device consists of seven major components: 12 V step-down transformer, half-wave rectifier, attenuator, wave-shaping circuit, arduino microcontroller, Liquid crystal display and micro SD card. The heart of the device is the arduino microcontroller that reads the period of the pulses from the shaping circuit and the output voltage from the scale resistor connected to the attenuator circuit in order to measure the levels frequency and voltage of the ac main source. By graphically compared the reading of the voltage obtained by the ac monitoring device with that of the standard Mastech voltmeter, it was shown that the device has a good correlation with the standard voltmeter with a deviation of ±0.21%, and this has proven that the device is capable of measuring ac voltage accurately. From the frequency test level results, it was found that the frequency measured by the device closely related to the frequency measured by the standard frequency meter. This shows that the device satisfied the requirement of the overall design. Hence, it can be used in the laboratory for demonstration and research purposes as well as in power plant industries.
 Keywords: Mains frequency, nominal voltage, half-wave rectifier, attenuator, wave-shaping circuit, Arduino microcontroller

Electrical-Model of ADITYA-U Tokamak

An Electrical-Model is developed for ADITYA-U Tokamak to study the generation of different shapes and duration of LVs out of the total available flux, which is 0.6 Vs in positive convertor supply. Loop voltage (LV) is required to be controlled during plasma discharge to optimize and predict the breakdown of plasma, proper impurity burn-through time, plasma current magnitude and duration of the plasma as per the experimental requirement. Loop voltage waveform is governed by selecting different magnitudes of resistance values, switching time and duration of external resistance in the wave shaping primary circuit. Loop voltage control system has been modelled using simulation code (Electrical-Model). Same results have been validated with the modelling of ohmic wave shaping circuit in MATLAB-Simulink. Temporal profile of loop voltage has been incorporated for ADITYA-U Tokamak for several plasma discharges, and detailed observations and results are presented in the paper.

Schmitt Trigger Circuits using Various Active Devices

A vast number of diverse analog circuit blocks have been arosed in the past few decades. A various active devices are Operational Amplifier (Op-Amp), Current Conveyor (CC), Operational Transconductance Amplifier (OTA), Differential Difference Current Conveyor (DDCC), Differential Difference Current Conveyor Transconductnace Amplifier (DDCCTA), Z-Copy Current Differencing Transconductance Amplifier (ZC-CDTA), Voltage Difference Transconductance Amplifier (VDTA) and so on. A review on Schmitt trigger circuits by using different active devices are presented in this paper since Schmitt trigger circuits are widely used in numerous applications such as in waveform generators, wave-shaping circuits, comparators, Bio-medical applications, analog processing systems, communication and instrumentation systems.

Schmitt Trigger Circuits using Various Active Devices

A vast number of diverse analog circuit blocks have been arosed in the past few decades. A various active devices are Operational Amplifier (Op-Amp), Current Conveyor (CC), Operational Transconductance Amplifier (OTA), Differential Difference Current Conveyor (DDCC), Differential Difference Current Conveyor Transconductnace Amplifier (DDCCTA), Z-Copy Current Differencing Transconductance Amplifier (ZC-CDTA), Voltage Difference Transconductance Amplifier (VDTA) and so on. A review on Schmitt trigger circuits by using different active devices are presented in this paper since Schmitt trigger circuits are widely used in numerous applications such as in waveform generators, wave-shaping circuits, comparators, Bio-medical applications, analog processing systems, communication and instrumentation systems.

A Novel Simple Differentiator Circuit Based on Carbon Nano Tube Field Effect Transistors Voltage Difference Transconductance Amplifier

: This paper brings in a new design, namely, voltage mode differentiator with an active element, Carbon Nanotube Field Effect Transistors Voltage Difference Transconductance Amplifier (CNVDTA). The circuit thus proposed needs one Carbon Nanotube Field Effect Transistors Voltage Difference Transconductance Amplifier (CNVDTA) element and a single capacitor. While fabricating IC’s in VLSI design, the proposed circuit proves more adaptable and applicable with the anticipated results. Methods: The proposed CNVDTA based voltage mode differentiator in CNFET technology was simulated at 32 nm at a voltage supply of ±0.9 V using the Cadence Virtuoso CAD tool. Results: It is also reported that the proposed circuit would function with ±0.9 V supply voltage and would also take care of the bias current of the order of 150 µA. Further, on the part of the transconductance (gm), it is electronically tunable with the help of bias current. Conclusion: The CNVDTA based differentiator has been found to be very useful in the triggering circuit of CRO’s, wave shaping circuits, power control circuits etc. It is also found useful in detecting the high-frequency components in the input signals.

Realization of Diverse Waveform Converters from a Single Nanoscale Lateral p-n Junction Cu2S-CdS Heterostructure.

A differentiator is an electronic component used to accomplish mathematical operations of calculus functions of differentiation for shaping different waveforms. Differentiators are used in numerous areas of electronics, including electronic analog computers, wave-shaping circuits, and frequency modulators. Conventional differentiators are fabricated using active operational amplifiers or using passive resistor-capacitor combinations. Here, we report that a single Cu2S-CdS heterostructure acts as a differentiator for performing numerical functions of input waveform conversion into different shapes. When a rectangular wave signal is applied through the tip of a conductive atomic force microscope, a spikelike wave signal is obtained from the Cu2S-CdS heterostructure. The Cu2S-CdS differentiator is able to convert a sine wave signal into a cosine wave signal and a triangular wave signal into a square wave signal similar to the classical differentiators. The finding of ananoscale differentiator at extremely small length scales may have profound applications in different domains of electronics.

A New H-Bridge Hybrid Modular Converter (HBHMC) for HVDC Application: Operating Modes, Control, and Voltage Balancing

An H-bridge hybrid modular converter (HBHMC) is proposed for high-voltage direct current (HVDC) applications. It uses a wave-shaping circuit consisting of series-connected full-bridge submodules (FBSMs) at the output of the main H-bridge converter. For a three-phase system, three HBHMCs are connected either in series (series-HBHMC) or in parallel (parallel-HBHMC) across the dc-link. The operating modes of HBHMC, novel modulation strategies for voltage balancing of FBSMs, and control of HBHMC-based HVDC system are presented in this paper. A detailed comparison between HBHMC and other hybrid topologies is performed on the basis of required number of switches and capacitors. The HBHMC has the features of dc fault blocking capability, lower footprint structure, and extra degree of freedom for submodules capacitor voltage balancing. The efficacy of the HBHMC-based HVDC system for three-phase balanced and unbalanced grid conditions and its fault-tolerant capability are validated using PSCAD simulation studies. Furthermore, the feasibility of the proposed converter under normal and dc fault conditions and of the proposed capacitor voltage control scheme is validated experimentally by using a three-phase grid-connected HBHMC laboratory prototype. The results demonstrate the effectiveness of the proposed HBHMC topology, control techniques, and satisfactory responses of the HBHMC-based HVDC system.

Design and analysis of a transformerless STATCOM based on hybrid cascaded multilevel converter

This paper presents a new concept of Static Synchronous COMpensator (STATCOM) based on a Hybrid Cascaded Multilevel Converter (HCMC). The HCMC consists of a two- level voltage converter and a wave-shaping circuit formed by cascaded H-bridge Sub-Modules (SM). Firstly, the operation principle and overall control strategy of HCMC are presented. After that, some key parameters including size of capacitors, numbers of sub-modules are in-depth analyzed. And then, a thorough comparison between the proposed HCMC-based STATCOM and conventional cascaded H-bridge based STATCOM is made, which turns out that the proposed HCMC-based STATCOM requires less number, size and stored energy of capacitors and has less power loss. Finally, a 35 kV/±50 Mvar HCMC-based STATCOM simulation model is constructed in PSCAD/EMTDC software platform. The simulation results validate the feasibility of the proposed HCMC-based STATCOM and the correctness of the analysis.

The analysis of additive noise of thermal test low-frequency cable fault detection based on M sequence correlation algorithm

The problem of low accuracy of off-line detecting on thermal test low-frequency cable faults could be solved by designing a cable fault detection system, based on FPGA program export M sequence code (linear feedback shift register sequence) as pulsed signal source. This paper discussed the design principle of spread spectrum time-domain reflectometry (SSTDR) reflection method, and introduced the hardware structure. Experimental platform established by this detection system could adapt to measurement of thermal test low-frequency cable with different lengths and could meet different additive noise environment. The off-line detecting on thermal test low-frequency cable faults could be solved by passing pre-filtering circuit and wave-shaping circuit processing, calculating transmitting and receiving pulse in transmit-receive buffer circuit, cable fault points could be located accurately through FPGA digital correlation algorithm. Testing data has shown that, in the M-sequence based SSTDR detection system, the additive noise and detected confidence can be described as a linear relationship.

Virtual Analog Models of the Lockhart and Serge Wavefolders

Wavefolders are a particular class of nonlinear waveshaping circuits, and a staple of the “West Coast” tradition of analog sound synthesis. In this paper, we present analyses of two popular wavefolding circuits—the Lockhart and Serge wavefolders—and show that they achieve a very similar audio effect. We digitally model the input–output relationship of both circuits using the Lambert-W function, and examine their time- and frequency-domain behavior. To ameliorate the issue of aliasing distortion introduced by the nonlinear nature of wavefolding, we propose the use of the first-order antiderivative method. This method allows us to implement the proposed digital models in real-time without having to resort to high oversampling factors. The practical synthesis usage of both circuits is discussed by considering the case of multiple wavefolder stages arranged in series.

Testing and Applications of Non-Linear Wave Shaping Circuits Based on Zener Diodes at Cryogenic Temperatures

Applications of wave-shaping clipping circuits based on Zener diodes are of great interest in a wide range of modern electronic systems. As well, given the strong interest in space research and trips to distant planets, where the journey takes long periods. Therefore, the matter requires reliance on electronic systems with special specifications commensurate with the nature of the extremely low-temperature environments, down to cryogenic level (around 90 K). So, the present paper was concerned with studying the stability of the performance of different non-linear wave-shaping systems, based on silicon Zener diodes, whenever operates at very low temperatures down to cryogenic levels. From which, it is clear that for BZX79-C4V7 and BZX79-C5V6 Zeners, such electronic systems were shown to be insensitive to temperature variations. On the other hand, low breakdown voltage Zeners (BZV86-1V4 and BZX83-C3V6), the clipping edges were shown to be increased with lowering temperatures from 300 K down to 93 K. Finally, for Zener diodes with VZ greater than 6.0 V (BZX83-C6V8 and BZX55C9V1), the temperature coefficient is positive, so the clipping edges decrease with lowering temperatures, for the same range of temperatures.

Optimal Redundancy Configuration of Wave-shaping Circuits and Director Switches in Hybrid Multi-level Converters

The alternate arm converter and hybrid cascaded multi-level converter are two promising hybrid multi-level converters for long-distance overhead-line-based high-voltage DC transmission systems. This article first outlines the basic topologies, mathematical equations, and switching patterns of both the alternate arm converter and hybrid cascaded multi-level converter; the initial required number of H-bridge cells in the wave-shaping circuits and series-connected insulated-gate bipolar transistors in the director switches of the alternate arm and hybrid cascaded multi-level converters are calculated. Then considering the operational characteristics, including the transient voltage stresses, the over-insulated-gate bipolar transistor and diode reliability of the individual semiconductor device in the alternate arm and hybrid cascaded multi-level converters are initialized. Further, the reliability analysis of the two hybrid multi-level converters is carried out, and the optimal redundancy configuration method of wave-shaping circuits and director switches is proposed and calculated by the first-order differences of the three-dimensional surfaces, in which an objective function is established that reconciles reliability and investment of hybrid multi-level converters. Finally, numerical calculations successfully validated the effectiveness of the proposed redundancy configuration method.

Parameter design and operating zone of hybrid cascaded multilevel converter under asymmetrical square‐wave modulation method of the director switch

Hybrid cascaded multilevel converter (HCMC) is a newly developed modular multilevel converter (MMC) with DC fault isolation capability. It is consisted of wave-shaping circuit (WSC) and direct switch (DS). This study studies the parameter design and operating zone of HCMC employing asymmetrical square-wave modulation at the DS. Analytical method of determining the asymmetrical component is derived through the energy balancing between AC side and DC side. Method of determining the required additional full-bridge cells is then deduced. By analysing the energy fluctuation flowing through the WSC, method of dimensioning the cell capacitors is proposed. Size of cell capacitance and insulated gate bipolar transistor current ratings for HCMC and traditional half-bridge MMC are compared. Feasible operating zone of the HCMC is studied and the overall design process of HCMC is summarised. Semiconductor cost, cell capacitance and arm inductance of HCMC and other DC fault tolerant MMC topologies are compared. It is shown that HCMC is able to isolate DC fault current with significantly lower cell capacitance, lower number of power semiconductors and no arm inductance compared with other MMC topologies. Detailed simulations on PSCAD/EMTDC confirmed the theoretical studies.

Modulation and Control for a New Hybrid Cascaded Multilevel Converter With DC Blocking Capability

The hybrid cascaded multilevel converter is a newly introduced voltage-source converter with dc blocking capability. It has two key parts, that is, the director switch (DS) made of insulated-gate bipolar transistors in series and the wave-shaping circuit (WSC) containing stacks of full-bridge submodules (FSMs). This paper focuses on the modulation schemes of the DSs and the WSCs. First, to reduce switching losses of the DSs, a novel asymmetrical square-wave modulation at a very low frequency is proposed, and the energy flow of the WSC under this modulation is analyzed. Second, modified phase-shifted carrier-based pulsewidth modulation (PSC-PWM) is presented to determine the number of FSMs to be inserted or bypassed; and the specified FSMs to be fired are selected according to the capacitor voltage-balancing strategy. Third, the capability to limit the short-circuit current during the dc fault is investigated, and fast ac overcurrent protection is designed. The effectiveness of the modulation and control strategies is verified by PSCAD/EMTDC simulations.

Development of wide range charge integration application specified integrated circuit for photo-sensor

A front-end application specified integrated circuit (ASIC) is developed with a wide dynamic range amplifier (WDAMP) to read-out signals from a photo-sensor like a photodiode. The WDAMP ASIC consists of a charge sensitive preamplifier, four wave-shaping circuits with different amplification factors and Wilkinson-type analog-to-digital converter (ADC). To realize a wider range, the integrating capacitor in the preamplifier can be changed from 4pF to 16pF by a two-bit switch. The output of a preamplifier is shared by the four wave-shaping circuits with four gains of 1, 4, 16 and 64 to adapt the input range of ADC. A 0.25-μm CMOS process (of UMC electronics CO., LTD) is used to fabricate the ASIC with four-channels. The dynamic range of four orders of magnitude is achieved with the maximum range over 20pC and the noise performance of 0.46fC + 6.4×10−4fC/pF.

Modified Grid-Connected CSI for Hybrid PV/Wind Power Generation System

The principle of a power conditioning unit for hybrid PV/wind power generation system is proposed. The proposed power conditioner is based on the current source inverter (CSI) topology. All energy sources are connected in parallel with a DC-bus through the modified wave-shaping circuits. To achieve the unity power factor at the utility grid, the DC-link current can be controlled via the wave-shaping circuits with the sinusoidal PWM scheme. In this work, the carrier-based PWM scheme is also proposed to minimize the utility current THD. The power rating of the proposed system can be increased by connecting more PV/wind modules through their wave-shaping circuits in parallel with the other modules. The details of the operating principles, the system configurations, and the design considerations are described. The effectiveness of the proposed CSI is demonstrated by simulation results.

A Simple Current-To-Time Converter

A simple circuit based on one CMOS two-input or gate serving as a voltage discriminator, a waveshaping circuit, and a logic circuit is described. It produces pulses with a pulse pause proportional to the reciprocal of its input current. If covers three decades, 1 ?A to 1 mA, with the conversion error less than 1 percent or five decades, 1 ?A to 10 mA, with the error less than 3 percent.

A pulse-repetition frequency doubler for square waves

Abstract It is possible to accomplish frequency multiplication of square waves by cascading elementary wave shaping circuits such as phase splitters, differentiators, OK gates, etc. A simple circuit arrangement for doubling the pulse-repetition frequency of a square wave is indicated following the same procedure.

Synthesis of the Hilbert transform of a train of rectangular pulses

A novel method of synthetising the Hillbert transform of a pulse train by nonlinear waveshaping circuits which avoids the use of complicated linear circuits is described.