Showing papers on "Integrating ADC published in 2014"

A Switched-Capacitor-Based Active-Network Converter With High Voltage Gain

Abstract: The voltage gain of traditional boost converter is limited due to the high current ripple, high voltage stress across active switch and diode, and low efficiency associated with large duty ratio operation. High voltage gain is required in applications, such as the renewable energy power systems with low input voltage. A high step-up voltage gain active-network converter with switched-capacitor technique is proposed in this paper. The proposed converter can achieve high voltage gain without extremely high duty ratio. In addition, the voltage stress of the active switches and output diodes is low. Therefore, low voltage components can be adopted to reduce the conduction loss and cost. The operating principle and steady-state analysis are discussed in detail. A prototype with 20-40-V input voltage, 200-V output voltage, and 200-W output power has been established in the laboratory. Experimental results are given to verify the analysis and advantages of the proposed converter.

Novel Three-Port Converter With High-Voltage Gain

Abstract: In this paper, a novel three-port converter (TPC) with high-voltage gain for stand-alone renewable power system applications is proposed. This converter uses only three switches to achieve the power flow control. Two input sources share only one inductor. Thus, the volume can be reduced. Besides, the conversion ratio of the converter is higher than other TPCs. Thus, the degree of freedom of duty cycle is large. The converter can have a higher voltage gain for both low-voltage ports with a lower turns ratio and a reasonable duty ratio. The voltage stress of switches is low; thus, conduction loss can be further improved by adopting low Rds(on) switches. Therefore, the converter can achieve a high conversion ratio and high efficiency at the same time. The operation principles, steady-state analysis, and control method of the converter are presented and discussed. A prototype of the proposed converter with a low input voltage 24 V for photovoltaic source, a battery port voltage 48 V, and an output voltage 400 V is implemented to verify the theoretical analysis. The power flow control of the converter is also built and tested with a digital signal processor.

Robust Time-Delay Control for the DC–DC Boost Converter

Abstract: This paper studies a robust control for regulating a boost converter capacitor output voltage The boost converter is inherently a highly nonlinear system that displays interconnected state variables and system parameter variations due to load change with input disturbances Therefore, a robust control scheme is required to cope with these characteristics The main objective of controlling the capacitor output voltage is to keep the output voltage constant under input voltage variations with fast response, and little overshoot and ripples To satisfy this objective, a robust control with time-delay concept is introduced The control utilizes time-delayed switching input to the converter, as well as output current and voltage variables, to replace the unknown dynamics and disturbance To prove the effectiveness of the algorithm, two operating point variations are considered: variations in source voltage, and changes in output load Simulations are performed using MATLAB/Simulink to show the effectiveness of the algorithm by choosing the output voltage lift, drop, settling time, and ripples as the system performance criteria Then, a comparison of the results is made of the proportional and integral control, and the sliding mode control An experimental test is also performed to demonstrate the effectiveness of the system

A Novel Transformerless Interleaved High Step-Down Conversion Ratio DC–DC Converter With Low Switch Voltage Stress

Abstract: In this paper, a novel transformerless interleaved high step-down conversion ratio dc-dc converter with low switch voltage stress is proposed. In the proposed converter, two input capacitors are series-charged by the input voltage and parallel-discharged by a new two-phase interleaved buck converter for providing a much higher step-down conversion ratio without adopting an extreme short duty cycle. Based on the capacitive voltage division, the main objectives of the new voltage-divider circuit in the converter are for both storing energy in the blocking capacitors for increasing the step-down conversion ratio and reducing voltage stresses of active switches. As a result, the proposed converter topology possesses the low switch voltage stress characteristic. This will allow one to choose lower voltage rating MOSFETs to reduce both switching and conduction losses, and the overall efficiency is consequently improved. Moreover, due to the charge balance of the blocking capacitor, the converter features automatic uniform current sharing characteristic of the interleaved phases without adding extra circuitry or complex control methods. The operation principles and relevant analysis of the proposed converter are presented in this paper. Finally, a 400-V input voltage, 25-V output voltage, and 400-W output power prototype circuit is implemented in the laboratory to verify the performance.

Design, analysis and implementation of a buck–boost DC/DC converter

Abstract: A novel buck–boost converter is presented in this study. This converter is based on Cuk converter. Therefore it inherits all the advantages of Cuk converter such as low output voltage ripple and minimal radio frequency interference. In addition, some implementation problems of KY converters are solved. The proposed converter has higher voltage gain in step-up mode in comparison with Cuk converter. Moreover, this converter expands the continuous conduction mode (CCM) operational region. In the suggested topology, the gate of the switch is referenced to ground, so this converter does not need a floating gate drive. Simulation results of the suggested converter are presented in different operational conditions. To verify the operation of the proposed converter, experimental results are provided using a hardware prototype that operates in both CCM and discontinuous conduction mode.

Minimum Time Control for Multiphase Buck Converter: Analysis and Application

Abstract: The combination of minimum time control and multiphase converter is a favorable option for dc-dc converters in applications where output voltage variation is required, such as RF amplifiers and dynamic voltage scaling in microprocessors, due to their advantage of fast dynamic response. In this paper, an improved minimum time control approach for multiphase buck converter that is based on charge balance technique, aiming at fast output voltage transition is presented. Compared with the traditional method, the proposed control takes into account the phase delay and current ripple in each phase. Therefore, by investigating the behavior of multiphase converter during voltage transition, it resolves the problem of current unbalance after the transient, which can lead to long settling time of the output voltage. The restriction of this control is that the output voltage that the converter can provide is related to the number of the phases, because only the duty cycles at which the multiphase converter has total ripple cancellation are used in this approach. The model of the proposed control is introduced, and the design constraints of the buck converter's filter for this control are discussed. In order to prove the concept, a four-phase buck converter is implemented and the experimental results that validate the proposed control method are presented. The application of this control to RF envelope tracking is also presented in this paper.

Non-isolated bidirectional DC–DC converter analysis and implementation

Abstract: A non-isolated bidirectional DC-DC converter is presented in this study. The configuration of the proposed converter is simple. The voltage gain of the proposed converter is higher than the conventional bidirectional DC-DC buck/boost converter in the step-up mode. In addition, the voltage gain is lower than the conventional buck/boost in step-down mode. Because of better gain performance of the proposed converter in comparison of the conventional converter it can work in wide voltage range than conventional converter. Therefore the proposed converter is applicable than the conventional bidirectional converter. Owing to simple structure, the control of the proposed converter is quite easy. The operation principle and steady-state analyses of the proposed converter in step-up and step-down modes are explored. Finally the laboratory prototype circuit is implemented to justify the validity of the theoretical analysis.

A new nested neutral point clamped (NNPC) converter for medium-voltage (MV) power conversion

Abstract: In this paper, a new Voltage Source Converter (VSC) for Medium Voltage (MV) applications is presented which can operate over a wide range of voltages (2.4kV-7.2KV) without the need for connecting power semiconductor in series. The operation of the proposed converter is studied and analysed. In order to control the proposed converter, a Space Vector Modulation (SVM) strategy which benefits from the switching state redundancy has been used. This strategy helps to control the output voltage and stabilize voltages of the flying capacitors in the proposed converter. Performance of the converter under different operating conditions is investigated in the MATLAB/Simulink environment.

Three-phase interleaved high-step-up converter with coupled-inductor-based voltage quadrupler

Abstract: This paper proposes a high-efficient DC-DC solution with the features of galvanic isolation, high-voltage gain, zero voltage switching operation, low input current ripple and high-power density The converter is implemented by a three-phase coupled inductor bridge to remove the bulky input electrolytic capacitors The introduced active clamp circuit recycles the energy stored in the leakage inductance and absorbs the voltage spikes on the main switch voltage The series configuration with a voltage doubler at the second side contributes to a high-voltage gain and reduces the voltage stress across the rectifier devices The output diode reverse-recovery problem is naturally mitigated by the leakage inductance of the coupled inductors Moreover, the active control with a neutral-point potential balance and a phase-deficient operation of the proposed converter are also studied A converter prototype is designed and evaluated to verify the theoretical analysis and demonstrate a superior performance over the prior studies

DC–DC converter with high voltage gain and reduced switch stress

Abstract: In this study, a novel high step-up dc–dc converter with high voltage gain and reduced switch stress is proposed. Utilising the coupled inductor to replace the boost inductor for high step-up converter is widely used in the application of high voltage gain converter. It can not only achieve a high voltage gain but also use the core effectively by using the coupled inductor. The techniques of voltage lift, voltage multiplier and clamp mode are also used in the proposed topology. Furthermore, the proposed converter can avoid the extreme duty cycle that will cause a lot of conduction losses. The leakage inductance energy of the coupled inductor will cause a huge voltage on the components of circuit, so that it needs to choose the components with high voltage and current ratings; then the efficiency is reduced and the cost is increased. The converter proposed in this paper can not only recycle the leakage inductance energy to the output but also increase the efficiency. A 300 W prototype converter which is implemented with an input voltage of 26 V and an output voltage of 400 V will demonstrate the effectiveness of this proposed converter.

Voltage Gain Enhancement for a Step-Up Converter Constructed by KY and Buck-Boost Converters

Abstract: In this paper, a novel voltage-boosting converter is presented, which combines one charge pump and one coupled inductor with the turns ratio. The corresponding voltage gain is greater than that of the existing step-up converter combining KY and buck-boost converters. Since the proposed converter possesses an output inductor, the output current is nonpulsating. After some mathematical deductions, an experimental setup with 12-V input voltage, 72-V output voltage, and 60-W output power is used to verify the effectiveness of the proposed converter.

Bidirectional isolated non-resonant DAB DC-DC converter for ultra-wide input voltage range applications

Abstract: This paper details efficiency optimized operation and design of a bi-directional and isolated five-level Dual Active Bridge (5LDAB) converter for an application that requires ultra-wide voltage and power ranges. The rated power of the considered converter is 7.5kW, the specified input voltage range is 150V ≤ V dc1 ≤ 800V and the output voltage is constant, V dc2 = 700V. In order to achieve high efficiency levels in a wide operating range, a modulation scheme is proposed to minimize the transformer rms current. Results of transformer rms currents and of efficiencies are presented for the 5LDAB and compared with the results obtained for an efficiency optimized conventional Dual Active Bridge (DAB) converter. Compared with the DAB topology, the 5LDAB converter can achieve an overall reduction of transformer rms currents and of conduction losses in the higher voltage regime of the operating range.

Isolated step-up converter based on flyback converter and charge pumps

Abstract: In this study, a single switch isolated step-up converter is presented, which is derived from the traditional flyback converter and charge pump concept. The proposed converter possesses an output inductor, so the output current is non-pulsating. Moreover, there are several advantages of the proposed converter over the traditional flyback converter, such as higher voltage conversion ratio with only additional four passive elements, and smaller voltage and current ripples, except the same switch voltage stress. In this study, some experimental results are provided to verify the effectiveness of the proposed converter.

A Cockcroft–Walton Voltage Multiplier Fed by a Three-Phase-to-Single-Phase Matrix Converter With PFC

Abstract: This paper proposes a single-stage three-phase-to-single-phase current-fed high step-up ac–dc matrix converter. The proposed converter inserts a boost-type matrix converter, which is formed by three boost inductors and six bidirectional switches, between a three-phase ac source and a Cockcroft–Walton voltage multiplier (CWVM). By using this topology associated with power factor correction technique, the proposed converter not only achieves almost unity power factor and sinusoidal input currents with low distortion but also obtains high voltage gain at the output end. Moreover, the matrix converter generates an adjustable-frequency and adjustable-amplitude current, which injects into the CWVM to regulate the dc output voltage and smooth its ripple. With this flexible injection current, the performance of the proposed converter is superior to the conventional CWVM, which is usually energized by a single-phase ac source. The operation principle, control strategy, and design considerations of the proposed converter are detailed in this paper. Finally, simulation and experimental results demonstrate the claims and validity of the proposed converter.

A Z-Source Half-Bridge Converter

Abstract: Applying an LC network into a half-bridge converter, a novel Z-source half-bridge converter is presented, in which less LC components are needed compared to the conventional one. This Z-source half-bridge converter can solve not only the problems of the shoot-through and limited voltage but also the problem of imbalance at the midpoint voltage of input capacitors. Furthermore, it can generate a broader range of output voltage values and much more kinds of waveforms, such as the varied positive or negative output voltages and the varied time ratio between positive and negative voltages, which are particularly desirable for some special power supplies, like the electrochemical power supply. Finally, the proposed converter is implemented in a prototype, and the experimental results can verify the effectiveness of the proposed converter.

IRD Digital Background Calibration of SAR ADC With Coarse Reference ADC Acceleration

Abstract: A coarse analog-to-digital converter (ADC) is used as the reference path to resolve the input interference problem in correlation-based background calibration of multistep ADCs. A 16-bit successive-approximation-register (SAR) ADC employing a subbinary architecture is calibrated with an 8-bit reference path, achieving a nearly 20 × reduction in convergence time and greatly improved steady-state linearity performance in simulation. The SAR ADC bit-weight calibration is based on the principle of internal redundancy dithering (IRD), a technique in which the bit decision thresholds are dithered by a pseudorandom bit sequence (PRBS) within the redundancy region. Aided by the coarse reference ADC, behavioral simulation shows that 89-dB signal-to-noise plus distortion ratio and the 115-dB spurious-free dynamic range (SFDR) are achievable with the proposed calibration for a SAR ADC with 1% digital-to-analog converter mismatch errors.

High gain step up DC-DC converter for DC micro-grid application

Abstract: In this paper a very high gain step up DC-DC converter is proposed. Maximum voltage gain in conventional boost converter like, switched inductor converter, switched capacitor converter, cascaded boost converter etc. are limited due to extreme duty cycle (i.e. duty cycle near to unity). Operation at extreme duty cycle leads to, serious reverse recovery problem at the switches, high conduction losses, high electromagnetic interference etc. Isolated converter such as fly-back converter, push-pull converter, forward converter, bridge converters etc. overcomes the above issues, where basically a transformer or coupled inductor is used to boost the voltage. But, inclusion of transformer or coupled inductor introduces voltage spike at the main switch and power loss due to leakage inductance. Recently, DC micro-grid gets major importance because of the significant increase in DC loads and demand of high quality power. These DC loads require different voltage levels based on their power ratings. Photo voltaic source (PV) is one of the prime source of energy in DC micro-grid. A very high voltage gain converter is necessary for DC micro-grid because of low PV source voltage. In this regard, here a step up DC-DC converter is proposed, which possess a very high voltage gain characteristic. Along with this, it provides the additional advantage of supplying power to two different loads (i.e. one for high voltage level and another for low voltage level), which makes it more suitable for DC micro-grid application. Steady state analysis and PWM control of the proposed converter are described in this paper. Theoretical verification of the proposed converter has been done by simulating it in MATLAB Simulink.

Analytical averaged loss model of a three-level T-type converter

Abstract: This paper has developed an analytical averaged loss model for a three-level T-type converter. Both the conduction loss and switching loss have been analysed. Apart from reduced output harmonics due to three-level operation, the T-type converter benefits from lower switching loss as a result of using of devices with lower voltage ratings and switching only half of the dc-link voltage. The loss distribution among the devices has been investigated with various modulation index and power factor. The T-type converter efficiency has also been evaluated against a two-level converter and a three-level neutral-point-clamped converter, where the T-type converter shows higher efficiency up to 30kHz switching frequency and can achieve 97% efficiency at 50kHz.

Single ADC Digital PFC Controller Using Precalculated Duty Cycles

Abstract: Traditional digital power factor correction (PFC) uses three sensors to measure the input and output voltages and the input current Each sensor, especially the input current one, increases the cost of the system and generates power losses in case of resistive sensors This paper presents a controller for boost PFC converters It uses precalculated duty cycles generated offline, and applies them to the switch In order to control the converter with nonnominal conditions, just one analog-to-digital converter (ADC) is used, which measures the output voltage Measuring the average and the ripple of the output voltage with this ADC, the controller takes compensation action for changes in the input voltage but also in the load of the converter The average value is used to control the input voltage changes, while the ripple value is used to control load changes These two loops present low frequency bandwidth, so the ADC and the whole system can be low cost Finally, a comparator is used to detect the zero-crossing of the input voltage, so the precalculated values are synchronized with the ac mains In this way, the converter only uses one ADC and one comparator, both with low bandwidth Results show that high power factor and normative compliance are reached, even under nonnominal conditions

A novel non-isolated switched inductor floating output DC-DC multilevel boost converter for fuelcell applications

Abstract: This paper presents a novel non-isolated switched inductor floating output DC-DC multilevel boost converter. Non-isolated high gain DC-DC converters are essential for fuelcell applications to boost the supply voltage with high conversion ratio. Conventional DC-DC boost converter is not suitable for high gain applications because of high voltage stress and high duty cycle. The proposed converter is non-isolated floating output DC-DC multilevel converter which combines the switched inductor and voltage multiplier functions to achieve high voltage gain. 2N-1 capacitors, 2N+2 diodes, two inductor and only one switch is required to design N-level DC-DC proposed converter. In the proposed converter topology blocking voltage across each device is less; hence proposed converter can be synthesized by using low voltage devices. The main advantage of proposed topology is high voltage gain is achieved without using transformer and extreme duty cycle. The gain of proposed converter is depends upon the number of levels at the output side. The proposed converter has been designed for three levels with rated power 450W, input voltage is 24V, output voltage is 480V and switching frequency is 50kHz. The proposed converter topology is simulated in MATLAB/SIMULINK.

A Three-Level Integrated AC–DC Converter

Abstract: In this paper, a new integrated three-level ac-dc converter is presented. The proposed converter integrates the operation of the boost power factor correction and the three-level dc-dc converter. The converter is made to operate with two independent controllers-an input controller that performs power factor correction and regulates the dc bus and an output controller that regulates the output voltage. The input controller prevents the dc-bus voltage from becoming excessive while still allowing a single-stage converter topology to be used. The paper explains the operation of the new converter in detail and discusses its features and a procedure for its proper design. Experimental results obtained from a prototype are presented to confirm the feasibility of the new converter.

A new 3X interleaved bidirectional switched capacitor converter

Abstract: An interleaved bidirectional switched capacitor converter with regulation capability is proposed in this paper This converter is able to step up the voltage to near three times and regulate the output, while maintaining continuous input current as well as small output voltage ripple Due to its natural interleaved structure, fewer components are required compared with traditional interleaved switched-capacitor converter with similar functionality The proposed topology can also be modified as unidirectional converter with reduced number of switches A PWM technique is proposed to regulate the output voltage A modeling method is presented which provides the voltage gain formula Criterion for high efficiency switched capacitor converter design is obtained A 10W 5V to 14V prototype of proposed SC converter with efficiency higher than 90% was realized The experimental results demonstrate the feasibility of proposed topology and regulation technique

Designing a Dynamic Ramp With an Invariant Inductor in Current-Mode Control for an On-Chip Buck Converter

Abstract: Designing a dynamic ramp with an invariant inductor in current-mode control for an on-chip Buck converter is proposed in this paper. This configuration maintains system stability under different input/output voltages without changing the inductor and compensation circuit. The dynamic ramp can be adjusted according to the variation in the output voltage or the voltage droop between the input voltage and the output voltage to maintain bandwidth and phase margin using the invariant inductor and compensation circuit. Finally, 14-V input voltage, 12-V output voltage, and 24-W output power with the dynamic ramp sampling the output voltage is implemented using MathCAD predictions, SIMPLIS simulation results, and experimental results to verify its viability and superiority.

A 12-Bit High-Speed Column-Parallel Two-Step Single-Slope Analog-to-Digital Converter (ADC) for CMOS Image Sensors

Abstract: A 12-bit high-speed column-parallel two-step single-slope (SS) analog-to-digital converter (ADC) for CMOS image sensors is proposed. The proposed ADC employs a single ramp voltage and multiple reference voltages, and the conversion is divided into coarse phase and fine phase to improve the conversion rate. An error calibration scheme is proposed to correct errors caused by offsets among the reference voltages. The digital-to-analog converter (DAC) used for the ramp generator is based on the split-capacitor array with an attenuation capacitor. Analysis of the DAC's linearity performance versus capacitor mismatch and parasitic capacitance is presented. A prototype 1024 × 32 Time Delay Integration (TDI) CMOS image sensor with the proposed ADC architecture has been fabricated in a standard 0.18 μm CMOS process. The proposed ADC has average power consumption of 128 μW and a conventional rate 6 times higher than the conventional SS ADC. A high-quality image, captured at the line rate of 15.5 k lines/s, shows that the proposed ADC is suitable for high-speed CMOS image sensors.

Analog integrator system and method

Abstract: Systems and methods are disclosed to integrate signals. Some embodiments include an integrator comprising an active input; a passive input; a first integrator having a first integrator input and a first integrator output; a second integrator having a second integrator input and a second integrator output; a first plurality of switches coupled with the first integrator input, the second integrator input, the active input, and the passive input; a second plurality of switches coupled with the first integrator output and the second integrator output; and a controller. The controller may be configured to control the operation of the first plurality of switches to switch the active input between the first integrator input and the second integrator input, and control the operation of the first plurality of switches to switch the passive input between the first integrator input and the second integrator input.

High efficiency boost converter with variable output voltage using a self-reference comparator

Abstract: This paper presents a boost converter with variable output voltage and a new maximum power point tracking (MPPT) scheme for biomedical applications. The variable output voltage feature facilitates its usage in a wide range of applications. This is achieved by means of a new low-power self-reference comparator. A new modified MPPT scheme is proposed which improves the efficiency by 10%. Also, to further increase the efficiency, a level converter circuit is used to lower the V dd of the digital section. The low input voltage requirements allow operation from a thermoelectric generator powered by body heat. Using this approach, a thermoelectric energy harvesting circuit has been designed in a 180 nm CMOS technology. According to HSPICE Simulation results, the circuit operates from input voltages as low as 40 mV and generates output voltages ranging from 1 to 3 V. A maximum power of 138 μW can be obtained from the output of the boost converter which means that the maximum end-to-end efficiency is 52%.

Biasing circuitry for mems transducers

Abstract: Circuitry for biasing a MEMS transducer and associated signal processing circuitry A reference voltage generator is configured to generate a reference voltage at a reference voltage node Control circuitry generates a drive signal to control a first current source which is operable to supply a current to the reference voltage generator in response to the drive signal A switched DC-DC converter, such as a charge pump has a voltage input connected to the reference voltage node and a voltage output for providing a bias voltage for the MEMS transducer The DC-DC converter cyclically switches in a sequence of states including at least a first state where a first converter capacitance is disconnected from the voltage input followed by a second state where the first converter capacitance is connected to the voltage input A second current source Is operable to supply a bias current in response to a voltage at a bias control node Switch control circuitry is configured to cyclically open and close a switch connected between the drive node and the bias control node, such that the switch is open during a time window that includes the time at which the switched DC-DC converter switches from the first state to the second state

A novel sepic based dual output DC-DC converter for solar applications

Abstract: This paper presents a sepic based dual output DC-DC converter, which is suitable for solar applications where two output voltages are needed at the same time. The proposed converter topology is the combination of sepic converter and high gain multilevel boost converter. Only one input source and switch is required to obtain two output voltages at the same time. One output voltage is obtained through high gain multilevel boost converter and other output voltage is obtained through sepic converter. Sepic converter operates in two modes, step-up or step-down depending on the duty cycle. The output voltage levels of high gain multilevel boost converter can be increases by adding diodes and capacitors without disturbing main circuit. The converter has been designed for 12V input supply with rated output parameters 180W, 230V and 50W, 36V. Switching frequency of applied gate pulse is 50 KHz with 75% duty cycle. Simulation is carried out using MATLAB/SIMULINK.

Controller for controlling a power converter

Abstract: A controller is provided for controlling a power converter that converts electrical input power of a wind turbine into electrical output power provided to a grid. The power converter includes grid-side and turbine-side converter parts. The controller comprises an input terminal for receiving a voltage reference signal associated with a predefined grid voltage and a frequency reference signal associated with a predefined grid frequency, and a network bridge controller adapted to control power conversion of the grid-side converter part. The network bridge controller includes a modulator for modulating gate drive command signals in the grid-side converter part based on a reference voltage and a reference angle derived from the voltage reference signal and the frequency reference signal. The modulator is adapted to modulate the gate drive command signals to maintain the predefined grid voltage and the predefined grid frequency in the power converter in case of failure within the grid.