Abstract: In this paper, a dc-link voltage sensorless control technique is proposed for single-phase two-stage grid-coupled photovoltaic (PV) converters. Matching conventional control techniques, the proposed scheme assigns the function of PV maximum power point tracking to the chopper stage. However, in the inverter stage, conventional techniques employ two control loops: outer dc-link voltage and inner grid current control loops. Diversely, the proposed technique employs only current control loop and mitigates the voltage control loop, thus eliminating the dc-link high-voltage sensor. Hence, system cost and footprint are reduced, and control complexity is minimized. Furthermore, the removal of the dc-link voltage loop proportional-integral controller enhances system stability and improves its dynamic response during sudden environmental changes. The system simulation is carried out, and an experimental rig is implemented to validate the proposed technique effectiveness. In addition, the proposed technique is compared with the conventional one under varying irradiance conditions at different dc-link voltage levels, illustrating the enhanced capabilities of the proposed technique.

Abstract: We have developed a broad bandwidth two-dimensional electronic spectrometer that operates shot-to-shot at repetition rates up to 100 kHz using an acousto-optic pulse shaper. It is called a two-dimensional white-light (2D-WL) spectrometer because the input is white-light supercontinuum. Methods for 100 kHz data collection are studied to understand how laser noise is incorporated into 2D spectra during measurement. At 100 kHz, shot-to-shot scanning of the delays and phases of the pulses in the pulse sequence produces a 2D spectrum 13-times faster and with the same signal-to-noise as using mechanical stages and a chopper. Comparing 100 to 1 kHz repetition rates, data acquisition time is decreased by a factor of 200, which is beyond the improvement expected by the repetition rates alone due to reduction in 1/f noise. These improvements arise because shot-to-shot readout and modulation of the pulse train at 100 kHz enables the electronic coherences to be measured faster than the decay in correlation between laser intensities. Using white light supercontinuum for the pump and probe pulses produces high signal-to-noise spectra on samples with optical densities 200 nm bandwidth.

Abstract: This paper presents an analog front end (AFE) that achieves a high noise efficiency by using a chopper amplifier with a 0.2-V supply inverter-based input stage followed by a 0.8-V supply stage. The high input-stage current needed to reduce the input-referred noise is drawn from the 0.2-V supply, significantly reducing power consumption. The 0.8 V stage provides high gain and signal swing, improving linearity. Biasing and common-mode rejection techniques for the ultra-low-voltage stage are presented. The AFE is implemented in a 0.18 $\mu \text{m}$ CMOS process and integrates the chopper low-noise instrumentation amplifier, a programmable-gain amplifier, and an antialiasing filter. The AFE consumes 0.79 $\mu \text{W}$ and achieves a competitive power efficiency factor (PEF) of 1.6 and an input noise of 0.94 $\mu \text{V}_{\text {rms}}$ integrated from 0.5 to 670 Hz while maintaining a 36 nV/ $\surd $ Hz input noise density down to 0.5 Hz. The included 0.8/0.2-V buck converter may be used to provide the 0.2-V supply at 72%–74% efficiency without significantly increasing noise, yielding a PEF of 1.8.

Abstract: Since their introduction, the SiC-based semiconductors have been of special interest to the field of power electronics, enabling increase in system efficiency, maximum operating temperature, and power density. In higher voltage range, these semiconductors are at early stage of development and yet are not commercialized. This paper investigates state-of-the-art noncommercialized 3.3-kV 400-A full-SiC MOSFETs where for the first time such MOSFETs are thoroughly characterized and their performance is evaluated and compared against similar rating Si counterparts. Extensive static and dynamic characterizations are done with emphasize on enabling conduction and switching loss calculation in any target application. I–V curves for MOSFET and Shottky-barrier diode (SBD), RDSon, C–V curves and threshold voltages are addressed by measurement at different temperatures. Moreover, the SiC MOSFETs are tested in chopper circuit with an inductive load for measurement of switching losses. This is done at 2-kV bus voltage from 50 up to 400 A load current. Finally, simulations are done in MATLAB/Simulink to evaluate the performance of 3.3-kV 400-A modules in medium-voltage high-power industrial drive application. The case study shows advantages of the 3.3-kV SiC MOSFET technology over 3.3-kV Si IGBTs and 1.7-kV SiC MOSFETs from efficiency, installed die area and power density points of view.

Abstract: Doubly fed induction generator (DFIG) based wind turbines are sensitive to grid faults due to utilising small-scale rotor side converter (RSC). The application of crowbar protection to improve the fault ride-through (FRT) capability of the DFIG converts it to a squirrel cage induction generator, which makes it difficult to comply with grid codes. This study proposes an innovative DC-link controllable fault current limiter (C-FCL) based FRT scheme for the RSC to improve the FRT capability of the DFIG. The proposed scheme replaces the AC crowbar protection and eliminates its disadvantages. The C-FCL does not affect the normal operation of the DFIG. By means of the proposed scheme, rotor over-currents are successfully limited during balanced and unbalanced grid faults, even at zero grid voltage. Also, the C-FCL prevents rotor acceleration and high torque oscillations. In this study, an analysis of the proposed approach is presented in detail. The performance of the proposed scheme is compared with the conventional crowbar protection scheme through simulation studies carried out in power system computer-aided design/electromagnetic transients, including dc software (PSCAD/EMTDC). Moreover, the main concept of the proposed approach is validated with an experimental setup and test results are presented.

Abstract: In this work, we propose a method to increase the parasitic input resistance caused by application of chopper modulation to indirect current feedback instrumentation amplifiers. The result is obtained by applying dynamic element matching to the input and feedback ports at the same frequency as chopper modulation. The proposed approach requires effective offset ripple rejection and equalization of the input and feedback common mode voltages. An in-amp architecture that meets both requirements and embodies the proposed input resistance boosting method is described. Experimental verification is provided by means of a prototype designed and fabricated using the $0.32~\mu \text {m}$ CMOS devices of the STMicroelectronics BCD6s process. The amplifier operates with a 3.3 V supply voltage and a total current absorption of $170~\mu \text {A}$ . An input impedance in excess of $1~\text {G}\Omega $ has been measured at a chopper frequency of 20 kHz. The input referred voltage noise density is 18 nV/sqrt(Hz) with a flicker corner of 0.2 Hz and 200 Hz bandwidth.

Abstract: This brief presents the design of a low-noise chopper capacitively coupled instrumentation amplifier (CCIA). To accommodate the input with large electrode offset (EOS), the amplifier includes a coarse digital dc-servo loop (DSL) in addition to a fine analog DSL that strikes a balance among noise, EOS handling range and circuit complexity. The chip is fabricated in a standard 0.13- $ {\mu }\text{m}$ CMOS process. The supply voltage is 1.2 V and the quiescent current is 2.9 $ {\mu }\text{A}$ . Measurement result shows that the chopper CCIA achieves a noise spectrum of 47 nV/ $\sqrt {{\text {H}}z}$ and is capable of handling EOS of ±50 mV.

Abstract: The Multi-Grid detector technology has evolved from the proof-of-principle and characterisation stages. Here we report on the performance of the Multi-Grid detector, the MG.CNCS prototype, which has been installed and tested at the Cold Neutron Chopper Spectrometer, CNCS at SNS. This has allowed a side-by-side comparison to the performance of 3He detectors on an operational instrument. The demonstrator has an active area of 0.2 m2. It is specifically tailored to the specifications of CNCS. The detector was installed in June 2016 and has operated since then, collecting neutron scattering data in parallel to the He-3 detectors of CNCS. In this paper, we present a comprehensive analysis of this data, in particular on instrument energy resolution, rate capability, background and relative efficiency. Stability, gamma-ray and fast neutron sensitivity have also been investigated. The effect of scattering in the detector components has been measured and provides input to comparison for Monte Carlo simulations. All data is presented in comparison to that measured by the 3He detectors simultaneously, showing that all features recorded by one detector are also recorded by the other. The energy resolution matches closely. We find that the Multi-Grid is able to match the data collected by 3He, and see an indication of a considerable advantage in the count rate capability. Based on these results, we are confident that the Multi-Grid detector will be capable of producing high quality scientific data on chopper spectrometers utilising the unprecedented neutron flux of the ESS.

Abstract: Recently, with research and development of SiC power devices, 1.2 kV SiC MOSFETs have become commercially available. The parasitic parameters, such as output capacitance, in each power device are not identical, because they depend on the device structure and material properties. Therefore, voltage sharing of turn-off operations under series-connection conditions of the power devices may be affected. This paper proposes a voltage balancing method for series-connected SiC MOSFETs under turn-off operations using digital control circuits. To compensate for the voltage unbalance conditions, a time-delay control for the gate drive circuit using a digital delay line is employed; experimental results using a buck chopper circuit using SiC MOSFETs and Schottky barrier diodes rated at 1.2 kV are also presented.

Abstract: This paper present a comparative study of speed control DC motor by using two different artificial intelligent controllers which are fuzzy logic controller (FLC) and artificial neural network (ANN) Intelligent controllers have gained wide popularity in the application of controlling system including DC motor speed control The type of motor used in this project is separately excited DC motor DC chopper is used to control the speed of DC motor by controlling their armature voltage of the motor The switching of the DC chopper is control by using pulse width modulation (PWM) technique This paper consists of two parts which are software development and hardware implementation The software part is the development of the DC motor model with the controller to achieve the desired speed by using MATLAB/Simulink In the hardware part, DC chopper is used to convert fixed DC voltage from power supply to variable DC voltage IGBT is used to control the variable DC voltage and hence, achieve the target speed of the DC motor DSPACE controller board is used for real-time interface of Simulink model and hardware development In summary, this paper demonstrated the efficiency of both controllers designed for the DC motor in term of speed control in both simulation and hardware implementation

Abstract: This paper proposes a method to extract the junction temperature of high-voltage and high-power p-i-n diodes. It is investigated that the swept-out charge during reverse recovery current fall time is affected by junction temperature variation, which makes the swept-out charge a possible thermo-sensitive electrical parameter (TSEP). Thanks to the specific package of high-power IGBT modules with p-i-n diodes, the swept-out charge of a p-i-n diode can be measured by the induced voltage v eE on the parasitic inductor L eE between Kelvin and power emitter terminals. In typical inductive half-bridge circuit, the comprehensive analysis of commutation between the upper p-i-n diode and lower enabled IGBT discloses the monotonic relationship among the reverse recovery charge, reverse current fall time, and junction temperature. A double pulse chopper circuit is used to validate the theoretical analysis. The experimental results show that the dependence between diode junction temperature and charge during the reverse recovery current fall time is approximately linear. A three-dimensional lookup table is calibrated and can be used to estimate the p-i-n diode junction operating temperature. Finally, an experimental comparison of four TSEPs for p-i-n diode is presented to verify the feasibility of the implementation of proposed TSEP.

Abstract: The Multi-Grid detector technology has evolved from the proof-of-principle and characterisation stages. Here we report on the performance of the Multi-Grid detector, the MG.CNCS prototype, which has been installed and tested at the Cold Neutron Chopper Spectrometer, CNCS at SNS. This has allowed a side-by-side comparison to the performance of $^3$He detectors on an operational instrument. The demonstrator has an active area of 0.2 m$^2$. It is specifically tailored to the specifications of CNCS. The detector was installed in June 2016 and has operated since then, collecting neutron scattering data in parallel to the He-3 detectors of CNCS. In this paper, we present a comprehensive analysis of this data, in particular on instrument energy resolution, rate capability, background and relative efficiency. Stability, gamma-ray and fast neutron sensitivity have also been investigated. The effect of scattering in the detector components has been measured and provides input to comparison for Monte Carlo simulations. All data is presented in comparison to that measured by the $^3$He detectors simultaneously, showing that all features recorded by one detector are also recorded by the other. The energy resolution matches closely. We find that the Multi-Grid is able to match the data collected by $^3$He, and see an indication of a considerable advantage in the count rate capability. Based on these results, we are confident that the Multi-Grid detector will be capable of producing high quality scientific data on chopper spectrometers utilising the unprecedented neutron flux of the ESS.

Abstract: This paper proposes a hybrid modular multilevel drive system based on a modular multilevel cascade inverter (MMCI) with double-star chopper cells (DSCC) and a two-level (2L) inverter to feed three-phase induction motors with open-end windings (OEWs). The proposed system is an alternative for high-speed motor drives based on a small-scale DSCC topology. A voltage reference technique is presented based on the analysis of the degrees of freedom of the system for generating the output voltage references, considering any voltage ratios of the dc links. The proposed system is evaluated in a symmetric scenario, in which the dc-link voltages are equal. Thus, the 2L inverter is set up to operate at the fundamental frequency, while the DSCC inverter synthesizes the output voltage references from high-quality waveform with a significant number of voltage levels. Experimental results obtained from a downscaled 10-kVA 380-V prototype driving a full loaded 3.7-kW OEW induction motor are provided to verify the viability of the proposed system.

Abstract: Pyroelectric infrared (PIR) sensors are the most popular presence detectors. However, their applications are limited to motion detection only, as the pyroelectric sensing element is only sensitive to radiated heat power fluctuation. This letter reports a chopped PIR (C-PIR) presence sensor, capable of detecting both the stationary and the moving occupants at high accuracy by introducing a narrow semi-transparent optical chopper to shutter the incident radiation periodically. More importantly, even though the narrow chopper can efficiently shutter the unidirectional infrared (IR) power radiated by stationary occupants, it has near-zero influence on the omnidirectional power radiated from the ambient environment. Therefore, the voltage difference generated by the C-PIR sensor between occupied and unoccupied scenarios can be directly used for identifying the presence of stationary occupants with high-accuracy. For moving occupant detection, the optical chopper can barely affect the variation of the radiated ...

Abstract: Currently, in electric railways, the old dc supply systems are reaching their limits. In several European railway networks, due to the line-voltage drops between substations, there are several sectors where traffic can no longer increase and where locomotives cannot operate at their nominal ratings. To improve the power capacity, a medium voltage dc (MVdc) three-wire supply system with voltage boosters based on imbricated cell multilevel choppers (ICMC) was proposed. In order to increase efficiency, the authors evaluate the potential of new SiC- mosfet s in this topology. An opposition method test bench using two ICMCs was built with 1.7-kV/300-A half-bridge modules. The design of the multilevel converters takes into account the constraints related to high switching frequency operation (up to 50 kHz). Thanks to the opposition method, losses in ICMCs can be determined by electrical and thermal measurements with good accuracy. Finally, solutions with SiC- mosfet s and Si-insulated gate bipolar transistors are compared in terms of efficiency.

Abstract: In this paper, we present a low-power, low-noise fully differential pseudo-open-loop preamplifier with programmable bandwidth for monitoring neural activities. The proposed pseudo-open-loop topology can achieve high-power-noise efficiency as well as high linearity and precise gain control over process. The proposed fully differential preamplifier can balance the common mode of the differential outputs without a common-mode feedback circuit, and bias the ac-coupled input transistors without an external reference. A current-ratio gain design can set a stable gain over process and bias current variations. A programmable embedded $g_{m}-C$ low-pass filter (LPF) can be tuned by adjusting bias current, so that the proposed preamplifier can be configured to be used in recording single neuron spikes or field potentials (EEG, ECoG). The proposed amplifier is configured to consume 400 nA at 2.5-V power supply; the total chip area is 0.189 mm2. The measured thermal noise floor is 85 nV/ $\surd $ Hz and input-referred noise is $1.69~\mu \text{V}_{\mathrm {rms}}$ from 0.3 Hz to 1 kHz when using a chopper stabilization technique to suppress 1/f noise. The fabricated preamplifier shows a noise efficiency factor of 2.43 in the fully differential topology.

Abstract: This study presents a new current-limiting soft-starter for a three-phase induction motor drive system using pulse width modulation (PWM) AC chopper. A novel configuration of three-phase PWM AC chopper using only four insulated gate bipolar transistors (IGBTs) is also proposed. The proposed control strategy does not require zero crossing detection circuits, which employed in thyristorised soft starters. It requires only one current sensor. The duty ratio of the chopper IGBTs is obtained from the closed-loop current control in order to limit the motor starting current at a preset value. Only two complementary gate pulses are obtained from the control circuit to control the four IGBT switches. The proposed control strategy is characterised by a simple control loop; thus, a low-cost processor can be used due to the low-computation burden. The superiority of the proposed strategy is proved theoretically and confirmed experimentally. The experimental work is developed using a laboratory prototype system composed of DSP-DS1104 digital control board and 1.5 HP induction motor. The proposed starter offers a smooth start-up for the motor speed, torque ripple minimisation, less number of semiconductor switches, less switching and conduction losses, less harmonics and improved input power factor.

Abstract: A high-repetition-rate X-ray chopper system has been developed for pump–probe time-resolved measurements with synchrotron radiation. This system has a rotating disc with 108 or 54 grooves (X-ray path on the disc) that provides an opening time of 1.17 or 0.52 µs with a rotating speed of 28,997 rpm. Also, this system could select single-pulse X-rays every 4 or 8 periods of the several-bunch structure operated at SPring-8, corresponding to an X-ray pulse frequency of 52.2 or 26.1 kHz, respectively, and is suitable for pump–probe studies of electronic devices such as next-generation memory devices.

Abstract: Large wind farms are usually located in remote and offshore areas. High voltage transmission systems that have long transmission distances are used to deliver the wind power to main grids. Weak AC grids have high impedance, low short circuit ratio (SCR) and/or low inertia compared to strong AC grids. The voltage stability of weak AC grids is a challenging issue that needs to be considered. This thesis compares weak and strong AC grids based on the voltage stability analysis. The steady-state characteristics of the weak AC grids are investigated. The power transfer characteristics of the wind farms that are connected to weak AC grids are studied under different voltage control technologies. The mitigation of the voltage recovery problems for weak AC grids is proposed by supplementary voltage control. The main characteristics of a weak AC grid are determined using P-V and V-Q curves. Different short circuit levels of the AC grid are presented with an increase in grid load and active power generation. Weak AC grid has a poor voltage stability limit and a low reactive power margin, which make the grid close to voltage instability. A static model is developed to study a test system including wind farm, AC grid, and reactive power compensators. Variable-speed wind turbines are examined under different control modes (power factor control, AC voltage control and reactive power control) using full power converters to increase the limit of transferred wind power to weak AC grids. Reactive power compensators of STATCOM, SVC, and fixed capacitor are compared to the full power converters. The capability of transferring power using STATCOM and SVC is greater than the full power converters. A dynamic model for the wind farm connected to the AC grid is developed and a STATCOM. The AC grid is modelled using two methods: as an ideal voltage source behind a Thevenin impedance and as a synchronous generator. A reactive power versus AC voltage droop is designed in STATCOM. The effectiveness of the STATCOM control is tested to increase the power transferred to the weak AC grids. The new supplementary voltage control is proposed using the full power converters with DC chopper considering three-phase to ground fault. Although the DC chopper is inadequate to keep the transient stability, a fast voltage control of the STATCOM is utilized to support the DC chopper in weak AC grids. The voltage recovery is improved using this controller after fault clearing.

Abstract: This paper proposes a capacitive touch sensing system (CTSS) using an adaptive chopper stabilization (ACS) method to achieve high noise immunity. The proposed ACS method quickly detects and adaptively filters out external noises, thereby achieving high noise immunity in the proposed CTSS. To verify the proposed ACS method, a readout integrated circuit (ROIC) was fabricated using a 0.35- $\mu \text{m}$ CMOS process technology with 18 V high-voltage devices and was measured using a 46-in capacitive touch sensor (CTS). When no external noises are induced into the CTS, the measured signal-to-noise ratio (SNR) of the ROIC is 45.8 dB at a reporting rate of 120 Hz. When external noises are induced into the CTS, the measured SNR of the ROIC using the ACS method is 44.5 dB, which is improved by 22.0 dB compared with the SNR achieved without using the ACS method. Therefore, the proposed ACS method effectively eliminates external noises induced into the CTS of the CTSS.

Abstract: Fluorescence is widely used for small-volume analysis and is a primary tool for on-chip detection in microfluidic devices, yet additional expertise, more elaborate optics, and phase-locked detectors are needed for ultrasensitive measurements. Recently, we designed a microfluidic analog to an optical beam chopper (μChopper) that alternated formation of picoliter volume sample and reference droplets. Without complex optics, the device negated large signal drifts (1/f noise), allowing absorbance detection in a mere 27 μm optical path. Here, we extend the μChopper concept to fluorescence detection with standard wide-field microscope optics. Precision of droplet control in the μChopper was improved by automation with pneumatic valves, allowing fluorescence measurements to be strictly phase locked at 0.04 Hz bandwidth to droplets generated at 3.50 Hz. A detection limit of 12 pM fluorescein was achieved when sampling 20 droplets, and as few as 310 zeptomoles (3.1 × 10–19 mol) were detectable in single droplets (...

Abstract: Energy and Environment, both is the main concern for every researcher all over the world. The energy harvesting from external ambient sources e.g. wind, solar, vibration, heat, radio frequency (RF) are emerging as promising alternative to existing energy resources. In recent years, the huge proliferation of RF /mobile communication in developing country like India has made RF energy harvesting as an attractive solution to the dramatically increasing energy needs. Energy Harvesting is the process of electronically capturing and accumulating energy from a variety of energy sources deemed wasted or otherwise said to be unusable for any practical purpose. This paper presents a model for harvesting radio frequency energy waves in the range of GSM 900 band (935-960 MHz) using a closed loop antenna. Then, the impedance matching is done to gain more power from antenna and the rectifier circuit converts an incoming RF signal to DC signal which is boosted using a chopper circuit and it is fed to the battery. The main objective of this paper is to find a way to design a system that can harvest the ambient Radio Frequency energy through the conversion to electrical energy that can be used in mobile charging, as RF signals are safe.

Abstract: In this paper an instantaneous maximum power extraction scheme is proposed as a PV power optimizer. The presented power harvesting scheme is rely on a weather-based power forecasting model in which the instantaneous value of the maximum power that should be extracted from the individual PV module is computed. The control unit of the proposed dc power optimizer is composed of a PI power controller and a PWM unit driving a SEPIC converter as a power conditioner. The chopper duty cycle is continuously adjusted such that the PV module is forced to operate near the maximum power point that is determined from the online measurements of the meteorological data model. The system is studied under both step down and step up modes of operation permitted by the SEPIC converter. The proposed scheme is investigated under different patterns of solar irradiance. The obtained results indicate both fast transient response and the good accuracy with low computation complexity due to the simple meteorological data model of the PV module. Compared with the commonly used perturb and observe (P&O) technique, the proposed scheme has better performance in terms of lower peak-peak power ripple. However, it has relatively lower tracking efficiency of (1–2)% due to the intentional reduction in the reference power signal to guarantee the fact that the actual harvested PV power can't exceed the reference value determined by the weather based model. The application area of the proposed scheme would be extended from a dc power optimizer for an individual PV to include microgrid applications, where commercially available temperature and solar irradiance transducers can be embedded with the distributed control unit of the SEPIC converter without dramatic increase to the initial cost of the overall system.

Abstract: Transient analysis is an important feature of doubly fed induction generator (DFIG). In this paper, for enhancing fault ride through (FRT) capability of DFIG based wind turbine a DC chopper is used which is connected across the DC-link capacitor. Two schemes were observed; the first scheme uses one insulated-gate bipolar transistor (IGBT) switch in series with a resistor to show the effect of the DC chopper magnitude. In this scheme, the best DC chopper resistor was obtained. The second scheme uses a circuit breaker to determine the best insertion time and duration of operation of the DC chopper. Proposed schemes were applied to a DFIG to investigate the transient analysis. Simulations were done by using PSCAD/EMTDC software. Simulation results show the DC chopper can adequately improve the FRT capability of the DFIG and also show the DC chopper resistor should be chosen carefully, because during a grid fault the large value may affect the system performance.

Abstract: This chapter investigates the effect of wind energy penetration on the frequency response of a multi-machine power network, with different time constants of a low pass filter (LPF) in the DC chopper of an energy capacitor system (ECS) The power network is made up of wind farms composed of fixed-speed induction generators interconnected to steam and hydro synchronous power plants Heavy and light loads were connected in the system The ECS is connected at the terminal of the wind turbine The LPF time constant parameter was varied for different cases, using the same wind speed for the wind turbine Scenarios with and without the synergy of a series dynamic braking resistor (SDBR) connected to the stator of the wind turbine and the ECS were investigated The results obtained were compared to a case where no frequency control was employed in the power network Simulations were carried out in Power System Computer Aided Design and Electromagnetic Transient Including DC The results show that a higher time constant of the LPF effectively damps the oscillations of the grid variables and quickly restores the system during network disturbance The SDBR was used to further enhance the performance of the ECS

Abstract: High voltage DC circuit breakers (DC CB) are essential components for the future DC transmission grid. One of the challenges after manufacturing the DC CB is testing it and confirming the working of the DC CB under different conditions. In this paper, a 320kV, 1.5kA test circuit is proposed for testing DC CB in conditions very close to real DC transmission systems. In the proposed circuit topology a chopper is used to regulate the DC voltage. A DC capacitor bank is used to provide the energy required during the fault replication. In the test circuit the initial DC voltage is boosted by 12% which results in a DC voltage drop of 88% at the end of discharge period. The test circuit keeps the voltage at nominal level as soon as the fault is cleared to enable testing dielectric stress. The proposed test circuit is modelled using PSCAD and the simulation results are shown which confirm the working principle of the proposed test circuit.