Adjustable Output Voltage Research Articles

A Novel Digital Closed Loop MEMS Accelerometer Utilizing a Charge Pump.

This paper presents a novel digital closed loop microelectromechanical system (MEMS) accelerometer with the architecture and experimental evaluation. The complicated timing diagram or complex power supply in published articles are circumvented by using a charge pump system of adjustable output voltage fabricated in a 2P4M 0.35 µm complementary metal-oxide semiconductor (CMOS) process, therefore making it possible for interface circuits of MEMS accelerometers to be integrated on a single die on a large scale. The output bitstream of the sigma delta modulator is boosted by the charge pump system and then applied on the feedback comb fingers to form electrostatic forces so that the MEMS accelerometer can operate in a closed loop state. Test results agree with the theoretical formula nicely. The nonlinearity of the accelerometer within ±1 g is 0.222% and the long-term stability is about 774 µg.

Closed loop control analysis of half-bridge 1] resonant converter based battery charger

Series Resonant Converters (SRC) popularly known as Line Level Controlled (LLC) converters are the most suitable topology of DC-DC power supply. The closed loop voltage regulation of a Half-Bridge (HB) Line-Level-Controlled (LLC) converter using PI controller is presented in this paper. Major objective of PI controller is to modulate frequency and duty ratio of gate signals. A voltage controlled oscillator (VCO) is generating the gating signals which will drive the MOSFETs for getting a regulated output voltage. The optimum LLC switching frequency ranges are derived so that converter can operate at higher efficiency. In this converter the primary switches (MOSFET) are operated with Zero Voltage Switching (ZVS) and secondary switches (Diodes) with Zero Current Switching (ZCS) to have lower losses and hence to obtain higher efficiency. Finally the theoretical results are verified by simulating the converter in MATLAB1/SimulinkTM circuit Simulator. The results obtained from simulation clearly signify the controller performance for adjustment of output voltage in case of variation in input line voltage and output current through the load. If the above observations are looked closely then it clearly indicates that the controller is executing the functions of regulating the output voltage. Whenever there is any variations in input line and output load then the output voltage across the load is able to follow the reference signal.

A novel control method for an isolated three-phase induction generator with constant frequency and adjustable output voltage

Summary This paper presents a new control method for a stand-alone wind-based induction generator system with constant frequency and adjustable output voltage. The proposed generator system consists of a six-phase cage-rotor induction machine with two separate three-phase stator windings and a three-phase static synchronous compensator (STATCOM). The first stator winding is fed by STATCOM and is used to excite the machine, while the second stator winding is connected to the generator external load. The main frequency of STATCOM is determined to be constant and equal to load-requested-frequency. Because the frequency of the induced emf in the second stator winding is same as this constant frequency, the generator output frequency is independent of the load power demand and rotor speed. The conventional PI controllers are used to regulate both the generator output terminal and STATCOM dc-link voltages. Some simulation and experimental results are presented to prove the validity and effectiveness of the proposed control method. Copyright © 2016 John Wiley & Sons, Ltd.

Reduction of THD in Seven Level H-Bridge Inverter with Reduced Number of Switches

Multi-Level Inverter technology have been developed in the area of high-power medium-voltage energy scheme. It is because of their advantages such as devices of high dv/dt rating, higher switching frequency, unlimited power processing, shape of output waveform and desired level of output voltage, current and frequency adjustment. This project proposed a new approach for reducing the total harmonic distortion in seven-level hybrid cascaded H-bridge multilevel inverter. The inverter with minimum number of switches is used for on-grid application of a PV system. Here a Sinusoidal pulse width-modulation (SPWM) technique is applied for obtaining carrier signals. This topology of asymmetrical DC voltage sources can be used there by enabling the scheme to reduce the Total Harmonic Distortion (THD) for medium voltage applications. The Maximum Power Point tracking algorithm is also used for extracting maximum power from the PV array connected to each DC link voltage level. Here we have used two DC link voltage levels(1:2). It has high performance with reduced Total Harmonic Distortion. The proposed system has verified and THD is obtained by using MATLAB/SIMULINK. The result is compared with the hardware prototype working model.

Constant Current versus Constant Voltage Subthalamic Nucleus Deep Brain Stimulation in Parkinson's Disease

Background: Subthalamic nucleus (STN) deep brain stimulation (DBS) is an established therapy for advanced Parkinson's disease (PD). Motor efficacy and safety have been established for constant voltage (CV) devices and more recently for constant current (CC) devices. CC devices adjust output voltage to provide CC stimulation irrespective of impedance fluctuation, while the current applied by CV stimulation depends on the impedance that may change over time. No study has directly compared the clinical effects of these two stimulation modalities. Objective: To compare the safety and clinical impact of CC STN DBS to CV STN DBS in patients with advanced PD 2 years after surgery. Methods: Patients were eligible for inclusion if they had undergone STN DBS surgery for idiopathic PD, had been implanted with a Medtronic Activa PC and if their stimulation program and medication had been stable for at least 1 year. This single-center trial was designed as a double-blind, randomized, prospective study with crossover after 2 weeks. Motor equivalence of the 2 modalities was confirmed utilizing part III of the Unified Parkinson's Disease Rating Scale (UPDRS). PD diaries and multiple subjective and objective evaluations of quality of life, depression, cognition and emotional processing were evaluated on both CV and on CC stimulation. Analysis using the paired t test with Bonferroni correction for multiple comparisons was performed to identify any significant difference between the stimulation modalities. Results: 8 patients were recruited (6 men, 2 women); 1 patient did not complete the study. The average age at surgery was 56.7 years (range 47-63). Disease duration at the time of surgery was 7.5 years (range 3-12). Patients were recruited 23.8 months (range 22.5-24) after surgery. At the postoperative study baseline, this patient group showed an average motor improvement of 69% (range 51-97) as measured by the change in UPDRS part III with stimulation alone. Levodopa equivalent medication was reduced on average by 67% (range 15-88). Patients were poorly compliant with PD diaries, and these did not yield useful information. The minor deterioration in quality-of-life scores (Parkinson's Disease Questionnaire-39, Quality of Life Enjoyment and Satisfaction Questionnaire) with CC stimulation were not statistically significant. Two measures of depression (Hamilton Rating Scale D17, Quick Inventory of Depressive Symptomatology - Self-Report) showed a nonsignificant lower score (less depression) with CC stimulation, but a third (Beck Depression Inventory) showed equivalence. Cognitive testing (Mini Mental State Examination) and emotional processing (Montreal Affective Voices) were equivalent for CC and CV. Conclusion: CC STN DBS is safe. For equivalent motor efficacy, no significant difference could be identified between CC and CV stimulation for nonmotor evaluations in PD patients 2 years after surgery.

Compact Pulse Topology for Adjustable High-Voltage Pulse Generation Using an SOS Diode

In this paper, a compact circuit topology is presented for pulsed power generation with a semiconductor opening switch (SOS). Such circuits require the generation of a fast forward current through the diode, followed by a reverse current that activates the recovery process. In general, magnetic switches are used to switch the diode current from forward to reverse. Therefore, adjustment of the output voltage of an SOS pulser is difficult. This paper introduces a circuit that allows an adjustable output voltage of the pulser. A solution is realized with a premagnetizing circuit on the primary winding of a pulse transformer (PT), so that a third winding is not needed. The primary capacitor voltage can now be varied while maintaining proper saturation of the PT.

Deposition of Al/Cu Multilayer By Double Targets Cylindrical DC Magnetron Sputtering System

A cylindrical direct current magnetron sputtering coater with two targets for deposition of multilayer thin films and cermet solar selective surfaces has been constructed. The substrate holder was able to rotate around the target for obtaining the uniform layer and separated multilayer phases. The Al/ Cu multilayer film was deposited on the glass substrate at the following conditions: Working gas = Pure argon, Working pressure = 1 Pa, Cathode current = 8 A and cathode voltage = -600 V .Microstructure of the film was investigated by X-Ray Diffraction and the scanning electron microscopy analyses. The elements profile was determined by glow discharge–optical emission spectroscopy analysis. During deposition, both targets with magnetron configuration were sputtered simultaneously by argon ions. A Plasma column on the targets surface was generated by a 290 G permanent magnet unit. Two DC power supply units with three phases input and maximum output of 12 A/1000V were used to deposit the multilayer thin films. A control phase system was used to adjust output voltage.

Modeling and Digital Control of a Single-Stage Step-Up/Down Isolated PFC Rectifier

This paper presents the dynamic modeling and digital control of a single-stage isolated current rectifier with power factor correction based on the integration of full-bridge and flyback converters. This converter is designed to operate with adjustable output voltage so that it can operate in two distinct operation modes, depending on the input and output voltages. Therefore, small-signal state-space average models are obtained for the converter operating in step-down and step-up operation modes, and analysis and design of the digital control system are included for different operating points. Experimental results based on a 3-kW prototype are presented to validate the proposed control system under distinct conditions.

A Single-Phase Single-Stage High Step-Up AC–DC Matrix Converter Based on Cockcroft–Walton Voltage Multiplier With PFC

This paper proposes a high-performance transformerless single-stage high step-up ac-dc matrix converter based on Cockcroft-Walton (CW) voltage multiplier. Deploying a four-bidirectional-switch matrix converter between the ac source and CW circuit, the proposed converter provides high quality of line conditions, adjustable output voltage, and low output ripple. The matrix converter is operated with two independent frequencies. One of which is associated with power factor correction (PFC) control, and the other is used to set the output frequency of the matrix converter. Moreover, the relationship among the latter frequency, line frequency, and output ripple will be discussed. This paper adopts one-cycle control method to achieve PFC, and a commercial control IC associating with a preprogrammed complex programmable logic device is built as the system controller. The operation principle, control strategy, and design considerations of the proposed converter are all detailed in this paper. A 1.2-kV/500-W laboratory prototype of the proposed converter is built for test, measurement, and evaluation. At full-load condition, the measured power factor, the system efficiency, and the output ripple factor are 99.9%, 90.3%, and 0.3%, respectively. The experimental results demonstrate the high performance of the proposed converter and the validity for high step-up ac-dc applications.

Development of Switching Power Supply with Precision Continuously Adjustable High Voltage

The techniques for developing a kind of the precision continuously adjustable high-voltage switching power supply are proposed, based on the constant frequency pulse width modulation strategies with SG3525, and the continuous output voltage adjustment effect is achieved through a gain amplifier controlled by MCU. The circuit is of the significant features such as high precision output voltages, continuously adjustable, a wide adjustment range and a low power consumption. The results of the experiments show that the output voltage is adjustable between 1KV and 25KV, and the maximum output voltage error is 1.6%.

Single-stage high power factor step-up/step-down isolated AC/DC converter

This study presents a single-stage (S 2 ) isolated current rectifier with power factor correction, based on a full-bridge flyback converter. This converter is designed to operate with adjustable output voltage so that it can operate in two distinct operation modes, step-up or step-down, depending on the input and output voltages. The proposed converter presents some features that make it attractive for many applications, such as constant switching frequency, step-down and step-up operation, high power level capability and the absence of an auxiliary pre-loading circuit to control the inrush current. This study presents the theoretical analysis of the converter for continuous conduction mode as well as experimental results based on a 3 kW prototype.

A buck converter with adaptive on-time PFM control and adjustable output voltage

This letter proposes a new adaptive on-time pulse-frequency modulation (PFM) circuit that operates at a wide range of supply voltage levels and that can generate various output voltage levels compared to conventional circuits. The circuit's peak inductor current is well-controlled; the magnitude of the output ripple voltage is constant, even when the supply and output voltage levels are significantly different. Since the ripple voltage is a noise component, constant ripple voltage is important for predictable noise of a power management system.

Single-Stage Double-Buck Topologies with High Power Factor

This paper presents two topologies for single-stage single-phase double-buck type PFC converters, designed to operate at high power factor, near sinusoidal input currents and adjustable output voltage. Unlike the known buck type PFC topologies, in which the output voltage is always lower than the maximum input voltage, the proposed converters can operate at output voltages higher than the ac input peak voltage. A reduced number of switches on the main path of the current are another characteristic of the two proposed topologies. To shape the input line currents, a fast and robust controller based on a sliding mode approach is proposed. This active non-linear control strategy, applied to these converters allows high quality input currents. A Proportional Integral (PI) controller is adopted to regulate the output voltage of the converters. This external voltage controller modulates the amplitude of the sinusoidal input current references. The performances of the presented rectifiers are verified with experimental results.

Using LLC Resonant Converter for Designing Wide-Range Voltage Source

LLC resonant converter with significant resonant inductance is proposed for designing an adjustable wide-range regulated voltage source. Large resonant inductance increases output voltage adjustment range and conversion efficiency, particularly at light loads. Soft switching is achieved for all power devices under all operating conditions by choosing the dead time and maximum switching frequency properly and operating in the converter's inductive region. Using a power-factor-correction (PFC) converter reduces the resonant converter's output voltage dependence to the variations of the main ac input voltage. Thus, the compensation of the load variations and the wide-range adjustment of the regulated output voltage can be achieved by using small switching frequency variations. The proposed method has been used to implement an adjustable wide-range voltage source (35-165 V dc), as an ion implanter arc power supply. An almost flat efficiency curve with maximum value of 94% has been achieved for the converter. Its output current can change from no load to 3 A dc.

Biologic Pacemakers: Past, Present, and Future

Cardiac pacemakers are one of the most important medical innovations of our era. The term, pacemaker, was coined by Albert Hymen, who described in 1932 an electromechanical instrument, powered by a spring-wound hand-cranked motor, which could provide electric shocks. In 1952, Paul Zoll developed transcutaneous pacing devices using large rechargeable batteries as power supplies. In 1957, engineer Earl Bakken, the founder of Medtronic, produced the first wearable external pacemaker for a patient of Dr C. Walton Lillehei. The transistorized pacemaker, housed in a small plastic box, had controls to permit adjustment of pacing rate and output voltage and was connected to electrodes leads that passed through the skin of a patient to terminate in electrodes attached to the surface of the myocardium. In 1958, transvenous endocardial pacing was first demonstrated by Seymour Furman, during which a catheter electrode was inserted via a patient’s basilic vein. The first clinical implantation into a human of a fully implantable pacemaker took place in October 1958 at the Karolinska

An Electrically Adjustable 3-Terminal Regulator for Post-Fabrication Level-Trimming with a Reliable 1-Wire Serial I/O

This paper describes a new technique for the design of 3-terminal regulators in which the output voltage level can be adjusted without additional terminals or extra off-chip components. This circuit restricts the increase in the number of terminal pins by using a pin as both a voltage supply output and a voltage setup input. The voltage setup information is introduced using a serial control signal from outside the chip. Using the intermediate voltage level between the supply voltage and the regulator output, the adjustment data in the internal nonvolatile memory are safely updated without noise disturbance. To input the setup information into the chip in a stable manner, we developed a new 1-wire serial interface which combines key pattern matching and burst signal detection. To ensure high reliability, we suggested a quantitative method for evaluating the influence of noise in our new interface using a simple model with superimposed random noise. Circuits additional to those for a conventional 3-terminal regulator, include a 1-wire serial communication circuit, a low-capacity non-volatile memory, and a digital to analog (D/A) converter. A test chip was developed using 0.35µm standard CMOS process, and there was almost no overhead to the conventional 3-terminal regulator in both chip area and power dissipation. In an on-board test with the test chip, we confirmed successful output voltage adjustment from 1.0V to 2.7V with approximately 6.5mV precision.

2D13 A Real-time Multi-channel Wireless Sensing Network for Structural Monitoring Applications

In this paper, a newly designed wireless sensing network platform for structural monitoring applications is presented and the results of a validation test performed in the authors' laboratory are reported. The main features offered by the proposed wireless platform are the capability of real-time and multi-channel data transmission, a high compatibility to different types of sensors, a highly efficient power-supply, and low-cost. Instead of adopting the most commonly used commercial wireless modems, the wireless communication is pursued by implementing an optimized and customized solution based on a recent System on Chip wireless transceiver. The Frequency Division Multiplexing method is exploited to ensure the real-time feature of the multi-channel data transmission. A simple and practical point-to-point topology is pursued. The usage of switching regulators which feature low quiescent current, highly efficient power conversion, the adjustable output voltage, and the high output power make this platform suitable for both low-power and non low-power structural monitoring applications involving different types of sensors. In order to validate the prototyped platform, a laboratory test is performed. The measurements of the acceleration response of a simple 3-storey structure mounted on a shaking table are acquired from both a wired DAQ system and the developed wireless platform. The data comparison enables to validate the efficacy of the real-time, multi-channel wireless transmission.

Design of an Adaptive Cathodic Protection Device Powered by Four Photovoltaic Solar Panels

Among a large number of photovoltaic applications, we are interested in the cathodic protection. It is one of the solutions used for the structures subjected to corrosion, mainly in oil and gas industries. In this work, optimum design sizing and system description are presented. Based on the design of a solar photovoltaic powered minicathodic protection system, a standard configuration of the photovoltaic system using a combination of four panels (two in series and two in parallel), has been derived. This standard size option must be matched at any cases of the cathodic protection station. For this purpose, an adaptive circuit, which is a voltage regulator with variable output, has been developed. Usually, cathodic protection systems work with constant current output, which is the necessary condition to procure immunity voltage of the structures against corrosion. The major difficulty to achieve this goal is the variations in the surrounding medium resistivity. To overcome this difficulty, several systems of control and regulation intended for cathodic protection system powered by photovoltaic energy have been designed and discussed. In our case, we propose an adaptive adjustment of the buck-boost converter output voltage by means of the microcontroller pulse width modulation output. In this paper, a complete design of the adaptive cathodic protection system using photovoltaic energy is carried out.

Control Strategies of a Hybrid Multilevel Converter for Expanding Adjustable Output Voltage Range

This paper proposes a new arrangement and new control strategies for a hybrid multilevel converter, aiming at a high-power high-efficiency converter system being free from harmonic distortion. The strategies enable one to expand the adjustable output voltage range up to 100% by keeping a very low harmonic distortion of the output voltage. The triangular-carrier-based pulsewidth modulation (PWM) and space-vector-based PWM strategies are applied to voltage control. The effectiveness is verified by simulation and experimental results. The proposed hybrid multilevel converter is applicable to medium-voltage networks as a high-power grid-interface converter.

An Analysis of the ZVS Two-Inductor Boost Converter under Variable Frequency Operation

The two-inductor boost converter has been previously presented in a zero-voltage switching (ZVS) form where the transformer leakage inductance and the MOSFET output capacitance can be utilized as part of the resonant elements. In many applications, such as maximum power point tracking (MPPT) in grid interactive photovoltaic systems, the resonant two-inductor boost converter is required to operate with variable input output voltage ratios. This paper studies the variable frequency operation of the ZVS two-inductor boost converter to secure an adjustable output voltage range while maintaining the resonant switching transitions. The design method of the resonant converter is thoroughly investigated and explicit control functions relating the circuit timing factors and the voltage gain for a 200-W converter are established. The converter has an input voltage of 20V and is able to produce a variable output voltage from 169V to 340V while retaining ZVS with a frequency variation of 1MHz to 407kHz. Five sets of theoretical, simulation and experimental waveforms are provided for the selected operating points over the variable load range at the end of the paper and they agree reasonably well. The converter has achieved part load efficiencies above 92% and an efficiency of 89.6% at the maximum power of 200W