A Bulk-Driven Quasi-Floating Gate Regulated Cascode Current Mirror and Its Application in Squarer Circuit

A regulated cascode current mirror (RGC) and its improved version with bulk driven quasi floating gate technique (BD-QFG) are presented in this paper. The proposed BD-QFG RGC current mirror (CM) is compared with the conventional (GD) RGC CM to show the performance improvement. The conventional and unconventional CM are implemented in Candace Virtuoso using 90 nm CMOS technology. For input current (Iin) varied from 0 to 200 μA and for 0.8 V supply voltage, the simulation results present that the proposed BD-QFG RGC CM has less variation in current transfer error (0.2%) as compared to the GD RGC CM (12%). The output voltage requirement for 200 µA input current is respectively 0.7 V and 0.17 V for the GD RGC CM and the BD-QFG RGC CM. The power consumption of the proposed circuit is 22.71 μW which is 0.15 μW higher than the GD RGC (22.56 μW). The total harmonic distortion (THD) of the proposed circuit is 0.4% which is 1.1% less than the conventional circuit (1.5%). All these improvements in the proposed BD-QFG RGC CM are attained at a cost of 0.05 GHz reduction in frequency (2.31 GHz). The minimum supply voltage of BD-QFG RGC CM and GD RGC CM is 0.4 V and

Capacitor Clamped Coupled Inductor Bi-Directional DC-DC Converter with Smooth Starting

In this paper, a new type of capacitor clamped coupled inductor bidirectional DC–DC converter is proposed, which offers high voltage gain with smooth starting current transients, as well as reduced stresses on the capacitor. Steady state operation, mathematical modelling, and state space modelling for the proposed converter are presented in detail. A simplified single voltage clamped circuit is developed to mitigate the voltage spikes caused due to the coupled inductor by recovering the leakage energy effectively. Moreover, the clamping capacitor helps in reducing the ripples in output voltage, which in effect significantly reduces the stress on the switch and offers less ripple content at the load terminals. Simulation of the proposed converter is carried out using Simulink/MATLAB for the conversion of 24V DC to 200V DC. For this conversion, simulation results have proven that there is reduction of 13.64% of capacitor voltage stresses. Further, under line varying conditions, converter responses have proven that there is a 119% and 25.25% reduction in input current and output voltage transients, respectively. Similarly, 25.25% and 76.5% transient reductions of input current are observed for line and control parameter variations. The hardware investigation of the converter was carried out with a 100 W, 24 V/200 V setup. The converter achieved efficiency of 93.8%. The observations supplement the simulation results.

INFLUENCE OF WIRE-EDM PARAMETERS ON SURFACE CHARACTERISTICS OF SUPERALLOY MONEL 400

Progressive development in the industrial field leads to the increasing demand for superalloys with enhanced mechanical properties, such as toughness, hardness, ductility, damping strength, tensile strength and improved surface finish. Monel 400, one of such superalloys, with the majority of its application in aerospace and marine fields demands a good super finish. There arises the need for some nonconventional processes like WEDM. This process is more effective to obtain complex shapes to close tolerance. This research focuses on clear understanding of the machining strategies with proper parametric combinations to achieve an improved surface finish, subsequently reducing the time and expense involved in the superfinishing procedure. The surface qualities of the selected samples are validated with the help of roughness profile and topography images. This study has proven that the increasing input current and wire feed rate (WFR) consistently decreases the surface roughness (SR; [Formula: see text] of the specimen. This paper also explains the effect of topographic parameters and microstructure over the resulting SR. In addition, the consistent contribution of WFR and input current toward the lower SR is established. The relationship between morphological behavior and parametric deviations is evaluated. A significant correlation found to exist between the rate of wire feed and the height parameters of SR such as [Formula: see text], [Formula: see text], etc.

Numerical simulation of hydrogen arcjet thruster using coupled sheath model

In the present work, a complete 2D chemical and thermal non-equilibrium numerical model coupled with a relatively simple sheath model is developed for hydrogen arcjet thruster. Conduction heat transfer in the anode wall is also included in the model. The operating voltages predicted by the model are compared with those in the literature and are found to be in close agreement. Power distributions for the various operating conditions are obtained, anode radiation loss primarily determines the thruster efficiency. Higher thruster efficiency was found to be associated with longer arc length. At cathode ion diffusion contribution dominates except at low input current where thermo-field electron current is dominant.

A Step-by-Step Design for Low-Pass Input Filter of the Single-Stage Converter

Active power factor correction converters are often introduced as the front stage of power electronic equipment to improve the power factor and eliminate higher harmonics. A Boost or Buck-Boost converter operating in discontinuous current mode is always adopted to achieve high power factor correction. In addition, the input current contains a large amount of higher harmonics, and a low-pass input filter is commonly adopted to filter it out. In this paper, a single-stage high-frequency AC/AC converter is taken as an example to demonstrate the design method of a passive low-pass filter. Firstly, the input side of the grid needs to meet the power factor and harmonic requirements. The preset parameters are set to a range to characterize the performance of the LC filter. The quantitative design method of input filter is proposed and summarized. Moreover, the sensitivity of the filter parameters is analyzed, providing a direction in practical applications. Preset parameters are all proved to conform to the preset range through PSIM simulation. Finally, a 130-W prototype is established to verify the correction of proposed design method. The power factor is around 0.935 and harmonic content in the input current is about 26.4%. All requirements can be satisfied.

Determining the Viability of the Use of Magneto-Rheological Fluid in a Low Cost Stroke Rehabilitation Device

<p>There are over 15 million people affected by strokes worldwide with a third left disabled. It is estimated that only 5 to 20 % regain upper limb functionality. However, research has shown that repetitive movement on the affected limb improves motor relearning. With the number of people affected by strokes rising each year the demand has begun straining hospital resources, therefore there is a need for some therapy to be moved away from clinical settings and into a person’s home. Robot assisted therapy is a growing field aiming to meet this demand. However currently there are no low cost devices able to actively exercise and strengthen a person’s hand during the acute (early) stage of stroke rehabilitation. This study is a part of a larger project involving the development of a low cost, assistive stroke rehabilitation device requiring a controllable damper. The aim of the study is to determine whether the use of magnetorheological fluid in a controllable damper is viable for use in the planned rehabilitation device. A rotary damper configuration was chosen as it can be made compact and avoid fluid leakage. To be deemed suitable for the application, the viscous torque of the damper needed to be controllable with varying input current. The required damping torques produced must be repeatable and needs to be generated below 34 C, the specified maximum operating temperature of the system. The performance of three vane designs for the rotary damper were investigated. These three designs were layered discs, a paddle and a helix. A test rig using a pulley configuration was designed and constructed to quantify the performance of the vane designs. The test rig recorded the opposing force and temperature measurements for each damper design. The measurements of interest were the off-state (no input current) torque, the achievable torque range, and also the consistency of the measurements. Experiments were conducted with the damper containing air to determine the pre-existing friction between the vane and housing, and water and motor oil were used as the damper fluid to investigate the performance of the designs with known fluid viscosities. Lastly experiments containing magneto-rheological fluid were conducted to determine the controllability and consistency of the viscous torque of each design. The paddle design was selected based on its range and consistency of produced torque, simplicity of the design and expected economical manufacture. With an input current of 0 to 2 A the damper produced a viscous torque range of 0.0036 Nm to 0.044 Nm, which was the equivalent opposing force of approximately 7.3 N. During testing of the various damper designs, a few imperfections were found. A modified version of the chosen damper was constructed to determine whether those features were manufacturing artifacts. It was found that the force measurements became smoother and previous periodic oscillations in the measurements were eliminated. The viscous torque of the paddle design was found to be controllable within the given operational conditions and therefore the use of magnetorheological fluid is a viable solution for use in a low cost stroke rehabilitation device.</p>