Showing papers on "Integrating ADC published in 2009"

An Analytical Investigation of DC/DC Power Electronic Converters With Constant Power Loads in Vehicular Power Systems

Abstract: Stability of multi-converter power systems, which exist in advanced more electric vehicles, is of great importance. The stability issue is investigated in this paper, and design considerations and limitations of the methods that stabilize the open-loop converters are presented. By stabilizing the open-loop converter, it is shown that the feedback loop design is usually translated into a conventional feedback design task. The behavior of the unstable converter is also discussed, and a method for decreasing the amplitude of the output voltage oscillations is proposed. The model of a tightly regulated practical converter is presented. This model is used to decide how much damping should be added to make the feeder converter stable. Furthermore, because we have this information about the load converter, the feeder converter can be redesigned so that it does not see the load converter as a constant power load.

DC-Voltage-Ratio Control Strategy for Multilevel Cascaded Converters Fed With a Single DC Source

Abstract: Recently, a multilevel cascaded converter fed with a single DC source has been presented. An analysis of the steady-state working limits of this type of converter is presented in this paper. Limits of the maximum output voltage and the minimum and maximum loading conditions for stable operation of the converter are addressed. In this paper, a way to achieve any DC voltage ratio (inside the stable operation area of the converter) between the H-bridges of the single-DC-source cascaded H-bridge converter is presented. The proposed DC-voltage-ratio control is based on a time-domain modulation strategy that avoids the use of inappropriate states to achieve the DC-voltage-ratio control. The proposed technique is a feedforward-modulation technique which takes into account the actual DC voltage of each H-bridge of the converter, leading to output waveforms with low distortion. In this way, the dc voltage of the floating H-bridge can be controlled while the output voltage has low distortion independently of the desired DC voltage ratio. Experimental results from a two-cell cascaded converter are presented in order to validate the proposed DC-voltage-ratio control strategy and the introduced concepts.

Step-up DC-DC converter for megawatt size applications

Abstract: This study describes a novel DC-DC converter concept which is capable of achieving very high step-up gains with megawatt (MW) level power transfers. The converter is based on two four-switch bridges around a LC circuit and does not utilise iron core transformers. The converter topology is simple and utilises thyristors as switches, with potentially soft switching operation. The high-voltage circuit does not suffer from excessive switch stresses or reverse recovery problems. The analytical modelling indicates that loading, and not the voltage gain, determines the converter size and the control input magnitude. For a given converter, the gain and either loading or operating frequency can be arbitrary selected. The converter shows good controllability with a linear characteristic if the operating frequency is used as the control input. The detailed digital simulation on PSCAD platform confirms conclusions from theoretical analysis on a 5 MW test system, which connects 4 kV source to 80 kV high voltage DC grid. The simulation studies of loses, with realistic internal resistances, indicate that efficiencies of around 95% could be expected.

Two Types of KY Buck–Boost Converters

Abstract: A novel voltage-bucking/boosting converter, named as KY buck-boost converter (i.e., 2D converter), is presented herein. Unlike the traditional buck-boost converter, this converter possesses fast transient responses, similar to the behavior of the buck converter with synchronous rectification. In addition, it possesses the non-pulsating output current, thereby not only decreasing the current stress on the output capacitor but also reducing the output voltage ripple. Furthermore, it has the positive output voltage, different from the negative output voltage of the traditional buck-boost converter. Above all, there are two types of KY buck-boost converters presented herein. In this paper, the basic operating principles of the proposed converters are first illustrated in detail, and second, some experimental results are offered to verify the effectiveness of the proposed topologies.

A Single-Inductor Step-Up DC-DC Switching Converter With Bipolar Outputs for Active Matrix OLED Mobile Display Panels

Abstract: A single-inductor step-up DC-DC switching converter with bipolar outputs is implemented for active-matrix OLED mobile display panels. The positive output voltage is regulated by a boost operation with a modified comparator control (MCC), and the negative output voltage is regulated by a charge-pump operation with a proportional-integral (PI) control. The proposed adaptive current-sensing technique successfully supports the implementation of the proposed converter topology and enables the converter to work in both discontinuous-conduction mode (DCM) and continuous-conduction mode (CCM). In addition, with the MCC method, the converter can guarantee a positive output voltage that has both a fast transient response of the comparator control and a small output voltage ripple of the PWM control. A 4.1 mm2 converter IC fabricated in a 0.5 mum power BiCMOS process operates at a switching frequency of 1 MHz with a maximum efficiency of 82.3% at an output power of 330 mW.

High step-up resonant push-pull converter with high efficiency

Abstract: A high-efficient current-fed push-pull converter is proposed for high output voltage applications supplied by low-voltage and high-current sources such as fuel cells and solar cells. The proposed converter conserves inherent advantages of a conventional current-fed push-pull converter such as low input current stress and high-voltage conversion ratio. The converter employs a voltage-doubler rectifier in order to remove the reverse-recovery problem of the output rectifying diodes and to provide much higher voltage conversion ratio. Additionally, by allowing the duty ratio < 0.5, the converter operates in wider input voltage range, and the ripple current of a boost inductor is reduced, compared with the conventional one. Moreover, as the duty ratio approaches 0.5, the ripple of the inductor current moves in close to zero. The operation of the proposed converter is analysed and experimental results obtained from a prototype verify the analysis. The prototype was implemented for an application requiring a 1.5 kW output power, input voltage range varying from 35 to 60 V, and 350 V output voltage. Experiment results show that minimum efficiency at full load is about 95.5%.

Power factor corrected 3-phase Ac-dc power converter using natural modulation

Abstract: A 3-phase pfc 100% duty-ratio buck converter and a 3-phase 0% duty-ratio boost converter can be used in parallel with their outputs in series to greatly reduce the ripple voltage in the output. They can also be used in series with their outputs in parallel to greatly reduce the ripple current in the output. A 3-phase 0% duty-ratio boost converter having isolated primary circuits for each phase is used when the inputs are in series.

A Three-Level Resonant Single-Stage Power Factor Correction Converter: Analysis, Design, and Implementation

Abstract: This paper presents a new single-stage power factor correction AC/DC converter based on a three-level half-bridge resonant converter topology. The proposed circuit integrates the operation of the boost power factor preregulator and the three-level resonant DC/DC converter. A variable-frequency asymmetrical pulsewidth modulation controller is proposed for this converter. This control technique is based on two integrated control loops: the output voltage is regulated by controlling the switching frequency of the resonant converter, whereas the DC-bus voltage and input current are regulated by means of duty cycle control of the boost part of the converter. This provides a regulated output voltage and a nearly constant DC-bus voltage regardless of the loading condition; this, in turn, allows using smaller switches and consequently having a lower on resistance helping to reduce conduction losses. Zero-voltage switching is also achieved for a wide range of loading and input voltage. The resulting circuit, therefore, has high conversion efficiency making it suitable for high-power wide-input-voltage-range applications. The effectiveness of this method is verified on a 2.3-kW 48-V converter with input voltage (90-265 Vrms).

Single-Switch Quasi-Resonant Converter

Abstract: A single-switch quasi-resonant converter is proposed to obtain high efficiency. Using a variable switching frequency control, this converter is continuously operated at the critical conduction mode for soft switching of the power semiconductor switch. By the resonance, the proposed converter reduces the turn-on loss of the switch without additional active switches and alleviates the reverse-recovery losses of the rectifying diodes. Furthermore, the voltage stress of the rectifying diodes due to the output series resonant circuit is clamped to the output voltage. Experimental results for the 48-V/160-W converter at the variable switching frequency are obtained to show the performance of the proposed converter.

High Step-Up Bidirectional Isolated Converter With Two Input Power Sources

Abstract: The objective of this paper is to develop a high step-up isolated converter with two input power sources. The proposed converter has two input ports for simultaneously converting two different input power sources with low voltages to a stable output power with a high voltage. Moreover, the demand of bidirectional power flow, which is dependent on the power management for charging and discharging power storage mechanisms, can also be satisfied in the proposed converter. According to various situations, the operational states of the proposed converter can be divided into three states, including a stand-alone state, a united power supply state, and a charge and discharge state. The effectiveness of the designed circuit topology is verified by experimental results, and the goals of high-efficiency conversion, high step-up ratio, and bidirectional power flow can be achieved by the proposed converter operation.

A Three-Phase Current-Fed Push–Pull DC–DC Converter

Abstract: In this paper, a new three-phase current-fed push-pull DC-DC converter is proposed. This converter uses a high-frequency three-phase transformer that provides galvanic isolation between the power source and the load. The three active switches are connected to the same reference, which simplifies the gate drive circuitry. Reduction of the input current ripple and the output voltage ripple is achieved by means of an inductor and a capacitor, whose volumes are smaller than in equivalent single-phase topologies. The three-phase DC-DC conversion also helps in loss distribution, allowing the use of lower cost switches. These characteristics make this converter suitable for applications where low-voltage power sources are used and the associated currents are high, such as in fuel cells, photovoltaic arrays, and batteries. The theoretical analysis, a simplified design example, and the experimental results for a 1-kW prototype will be presented for two operation regions. The prototype was designed for a switching frequency of 40 kHz, an input voltage of 120 V, and an output voltage of 400 V.

Three-Level AC–DC–AC Z-Source Converter Using Reduced Passive Component Count

Abstract: This paper presents a three-level AC-DC-AC Z-source converter with output voltage buck-boost capability. The converter is implemented by connecting a low-cost front-end diode rectifier to a neutral-point-clamped inverter through a single X-shaped LC impedance network. The inverter is controlled to switch with a three-level output voltage, where the middle neutral potential is uniquely tapped from the star-point of a wye-connected capacitive filter placed before the front-end diode rectifier for input current filtering. Through careful control, the resulting converter can produce the correct volt-second average at its output, while simultaneously achieving inductive voltage boosting by shooting through either an appropriately selected inverter phase-leg or two phase-legs being commanded simultaneously. More interestingly, these performance features are achieved with no increase in the number of semiconductor commutations, and hence, no increase in switching losses. The proposed converter therefore offers a low-cost alternative to applications that need to ride through frequent input voltage sags. For confirming the converter performance, experimental testing using a constructed laboratory prototype is performed with its captured results presented in a later section of the paper.

An Improved AC–DC Single-Stage Full-Bridge Converter With Reduced DC Bus Voltage

Abstract: A new ac-dc single-stage voltage-fed pulsewidth-modulation (PWM) full-bridge converter is proposed in this paper. The converter can simultaneously perform input power factor correction and dc-dc conversion using conventional phase-shift PWM and can maintain a primary-side dc bus voltage of less than 450 V even at a high input line voltage of 265 Vrms. This is a combination of features that few, if any, other converters of the same type have. The proposed converter has these features due to the novel implementation of an asymmetrical auxiliary transformer winding that is placed in series with the input inductor and acts as a boost switch. In this paper, the operation of the proposed converter is explained in detail, its outstanding features are discussed, and a detailed design procedure is given and demonstrated with an example. Experimental results that confirm the feasibility of the converter and its ability to meet IEC1000-3-2 Class D standards for electrical equipment are also presented in this paper.

Single-Stage Single-Switch Switched-Capacitor Buck/Buck-Boost-Type Converter

Abstract: A new dc-dc converter featuring a steep step-down of the input voltage is presented. It answers a typical need for on-board aeronautics modern power architectures: power supplies with a large conversion ratio able to deliver an output voltage of 1-1.2 V. The proposed structure is derived from a switched-capacitor circuit integrated with a buck converter; they share the same active switch. The proposed solution removes the electromagnetic interference (EMI) emission due to the large di/dt in the input current of the switched-capacitor power supplies. Compared with a quadratic buck converter, it presents a similar complexity, a smaller reduction in the line voltage at full load (but less conduction losses due to smaller input inductor current and capacitor voltage), lower voltage stresses on the transistor and diodes, lower current stresses in the diodes, and smaller size inductors. A similar structure using a buck-boost converter as the second stage is also presented. The experimental results confirm the theoretical developments.

Design of Reconfigurable and Robust Integrated SC Power Converter for Self-Powered Energy-Efficient Devices

Abstract: Motivated by emerging self-sustained low-power applications, an integrated power supply solution with a reconfigurable step-up/down switched-capacitor power stage and a dual-loop adaptive gain-pulse control is presented. It makes use of a reconfigurable power stage structure to implement variable gain ratios that provide efficient voltage conversion within wide input/output voltage and power ranges. It also employs an interleaving regulation scheme to significantly reduce the input inrush currents and the output voltage ripples with fast transient response. Design strategy, system optimization, and circuit implementation are addressed in detail. The converter was designed with a standard 0.35-mum digital CMOS n-well process. With an input voltage ranging from 1.5 to 3.3 V, the converter achieves variable step-up/down voltage conversion with a maximum load current of 90 mA. The maximum efficiency is 88%. The converter responds to a 70-mA load-current step change within 4.6 mus, while it robustly operates under a 1.8-V input supply variation. The design can be easily extended and reconfigured for different operation and application scenarios.

Step-up dc/dc voltage converter with improved transient current capability

Abstract: A DC/DC voltage converter includes an inductive switching voltage regulator and a capacitive charge pump connected in series between the input and output terminals of the converter. The charge pump has a second input terminal connected to the input terminal of the converter. This reduces the series resistance in the current path by which charge is transferred from the capacitor in the charge pump to the output capacitor and thereby improves the ability of the converter to respond to rapid changes in current required by the load.

Analysis and Design of a Single-Stage Parallel AC-to-DC Converter

Abstract: In this paper, a single-stage (S2) parallel ac-to-dc converter based on single-switch two-output boost-flyback converter is presented. The converter contains two semistages. One is the boost-flyback semistage, which transfers partial input power transferred to load directly through one power flow path and has excellent self-power factor correction property when operating in discontinuous conduction mode even though the boost output is close to the peak value of the line voltage. The other one is the flyback dc-to-dc (dc/dc) semistage that provides the output regulation on another parallel power flow path. With this design, the power conversion efficiency is improved and the current stress of control switch is reduced. Furthermore, the calculation process of power distribution and bulk capacitor voltage, design equations, and design procedure for key parameters are also presented. By following the procedure, an 80 W prototype converter has been built and tested. The experimental results show that the measured line harmonic current at the worst condition complies with the IEC61000-3-2 class D limits, the maximum bulk capacitor voltage is about 415.4 V, and the maximum efficiency is about 85.8%. Hence, the proposed S2 converter is suitable for universal input usage.

Novel bidirectional DC-DC converter with high step-up/down voltage gain

Abstract: This paper presents a novel bidirectional DC-DC converter with high step-up/down voltage gain by using the coupled-inductor technique. The high step-up voltage gain is achieved when the energy is transferred from the battery to DC-bus, and the high step-down voltage gain is achieved from DC-bus to the battery. High efficiency is obtained since the energy stored in leakage-inductor is recycled. Also, the operating principles and voltage gain of the proposed converter are discussed in detailed. Finally, a laboratory prototype with battery voltage 24 V, DC-bus voltage 200 V and output power 200 W is implemented to validate theoretical analysis.

Method and apparatus to control a power factor correction circuit

Abstract: A controller for use in a power factor correction (PFC) converter is disclosed. An example controller includes an integrator coupled to receive a voltage sense signal responsive to a magnitude of an ac voltage source. The ac voltage source is coupled to an input of the PFC converter, which is coupled to an energy transfer element, which is coupled to a power switch. The integrator is further coupled to receive a current sense signal responsive to a current flowing in the power switch when the power switch is on. The integrator is to generate an integrator output signal in response to the voltage sense signal and the current sense signal. On/off logic is to be coupled to drive the power switch on and off to control a transfer of energy through the energy transfer element to a load coupled to an output of the PFC converter. The on/off logic is coupled to terminate an on time of the power switch when the integrator output signal reaches a threshold value. A gain of the integrator circuit is adjusted in response to the voltage sense signal such that the threshold value is substantially constant independent of the magnitude of the ac voltage source when a magnitude of the load is constant.

UPS frequency converter and line conditioner

Abstract: Systems and methods disclosed herein monitor and control input to a converter in one or more of a UPS, a frequency converter, or a line conditioner. Distortion due at least in part to ripple voltage can be removed from a control signal that controls input current to the converter. The systems and methods described herein afford a simple and effective way to reduce or eliminate one or more of subharmonic oscillation and total harmonic distortion from a converter input current during synchronous and asynchronous modes of operation. The converter may include one or more of a rectifier and an inverter.

Design, study, modelling and control of a new single-phase high power factor rectifier based on the single-ended primary inductance converter and the Sheppard-Taylor topology

Abstract: A new single-phase power factor corrector (PFC) based on the Sheppard-Taylor topology is studied. Compared with conventional PFCs, this topology facilitates a better input current tracking, lower voltage stresses across the devices and larger output voltage range for the same operating area. The converter is integrated as a PFC at the DC-end of a single-phase diode bridge. Pulse-width-modulated (PWM) multi-loops control schemes are proposed and developed in order to ensure a unity power factor at the AC-source side and a regulated voltage at the DC-load side. The first control method uses the simple and robust hysteretic-based controller; the second employs a conventional PI regulator; and the third is based on the model nonlinearity compensation approach. The design of the last two control methods is based on the knowledge of a mathematical model that would accurately represent the converter. This model is developed in this paper using the state-space averaging technique, and then the small-signal transfer functions of the converter are derived for linear control design purpose. The performance of the different control strategies is evaluated through simulation experiments carried out on a numerical version of the converter. The implemented model of the converter is obtained by using the switching function technique. The control system is tested under both rated and disturbed operating conditions. The system performance is evaluated in terms of source current total harmonic distortion (THD), input power factor, DC voltage stabilization, and regulation following load variations.

Efficiency optimization of an automotive multi-phase bi-directional DC-DC converter

Abstract: The paper proposes methods to improve the efficiency of a bi-directional, multi-phase buck+boost DC-DC converter for application in Hybrid Electrical Vehicles (HEV) or Fuel Cell Vehicles (FCV) Thereto, the modulation strategy for a highly-compact, 30kW/Liter, constant-frequency soft-switching converter is optimized based on a converter loss model that includes the losses in the power semiconductors and the buck+boost inductor An algorithm for numerical calculation of the optimum switching times is given, whereas the values for the loss-optimized operation of the converter are stored in a lookup-table that is accessed by the digital controller In addition, a novel method and control concept to ensure a Zero Voltage Switching (ZVS) of all semiconductor switches by determination of a zero voltage across the MOSFET switches with analog comparators is proposed that results in the lowest inductor RMS currents for ZVS operation at the same time Furthermore, at low output power an absolute efficiency gain of over 28% is achieved by partial operation of the six interleaved converter phases A detailed description on the control concept that determines the optimum number of activated phases for the current operating point of the converter is given and verified by experimental results The measurements prove the capability to instantaneously switch the number of active phases during operation without a overshoot or drop in the converter output voltage

DC/DC Buck Converter Using Internal Model Control

Abstract: An internal model control with a conditional integrator is proposed for the robust output regulation of a DC/DC buck converter. Based on the input–output linearization from the state-space averaged model of DC/DC buck converter, the robust output regulation problem of the converter can be converted into a robust stabilization problem of an augmented system consisting of the given buck converter and the internal model by introducing a proper internal model. The procedures include the design of an internal model with conditional integrator and a sliding-mode robust controller. Also the closed-loop robust stability is theoretically analyzed. Finally, the effectiveness of the proposed converter is verified in comparing the proposed controller performance with open-loop control, single-loop proportional-plus-integral control, and double-loop proportional-plus-integral control under load disturbances and supply voltage variations.

A 900W, 300V to 50V Dc-dc Power Converter with a 30MHz Switching Frequency

Abstract: Designers of power conversion circuits are under relentless pressure to increase power density while maintaining high efficiency. A primary path to higher power density is the use of increased switching frequency. In this paper it is argued that the use of switching frequencies in the VHF band (30MHz-300MHz) are a viable path to the achievement of substantive gains in power density. Evidence for this viewpoint is presented in the form of an unregulated 900W prototype dc-dc converter with a 30MHz switching frequency, an input voltage range of 270VDC to 330VDC, and an output voltage of 50VDC. This converter uses a quad module architecture with series input and parallel output to provide acceptable efficiency with the specified input voltage range. This converter operates with peak output power of 1kW at 330VDC input, and has an efficiency of ≫ 78% under nominal conditions, with maximum efficiency near 80%.

Single-Stage Soft-Switching Converter With Boost Type of Active Clamp for Wide Input Voltage Ranges

Abstract: A single-stage soft-switching converter is proposed for universal line voltage applications. A boost type of active-clamp circuit is used to achieve zero-voltage switching operation of the power switches. A simple DC-link voltage feedback scheme is applied to the proposed converter. A resonant voltage-doubler rectifier helps the output diodes to achieve zero-current switching operation. The reverse-recovery losses of the output diodes can be eliminated without any additional components. The DC-link capacitor voltage can be reduced, providing reduced voltage stresses of switching devices. Furthermore, power conversion efficiency can be improved by the soft-switching operation of switching devices. The performance of the proposed converter is evaluated on a 160-W (50 V/3.2 A) experimental prototype. The proposed converter complies with International Electrotechnical Commission (IEC) 1000-3-2 Class-D requirements for the light-emitting diode power supply of large-sized liquid crystal displays, maintaining the DC-link capacitor voltage within 400 V under the universal line voltage (90-265 Vrms).

A 9b 14µW 0.06mm 2 PPM ADC in 90nm digital CMOS

Abstract: As CMOS dimensions scale down, time-domain resolution of digital signals improves but the voltage resolution of analog signals degrades [1]. In this paper, we introduce an ADC architecture based on Pulse Position Modulation (PPM), which relies more on time resolution than on amplitude resolution. In PPM (Fig. 9.4.1(a)), a continuous-time comparator compares the input signal with a voltage ramp. The time interval between the ramp starting point, which is synchronous with the reference clock, and the instant the input signal crosses the ramp (i.e. [t 1 , t 2 , t 3 , Ω] in Fig. 9.4.1(a)) is measured by a 2-step time-to-digital converter. Assuming the ramp slope is constant, we can calculate the input-signal amplitude from the measured time vector.

System and method for limiting input-current surge in a switching mode power supply

Abstract: A power supply comprises an input voltage detector that detects a drop in input voltage that corresponds to an input voltage loss. A power converter is coupled to the input voltage detector. The power converter, which may be a boost converter or a power factor correction converter, has a switching device that is actuated in accordance with a duty cycle. A duty cycle adjuster is responsive to detection of the drop in the input voltage to adjust the duty cycle of the switching device in order to limit an input current surge through the switching device below a desired level after the input voltage returns.

Control of Venturini Method Based Matrix Converter in Input Voltage Variations

Abstract: Matrix converter is a single-stage converter which directly connects a three-phase voltage source to a three-phase load without dc-link components Therefore, any harmonic distortion and imbalance in input voltage directly reflect to the output of the converter Recently, many researchers have made an effort to cope with this problem In this paper, under distorted input voltage conditions, behaviors of the MC controlled with Venturini method are analyzed and a PI controller based compensation method to prevent negative effects of input voltage is proposed Since the proposed method is based on closed loop control of the output currents, it not only reduces the output harmonic contents but also ensures a stable control of the load currents Some results are presented to prove the effectiveness of the proposed compensation technique

Analog-to-digital converter, analog-to-digital converting method, solid-state image pickup device, and camera system

Abstract: An analog-to-digital converter that converts an analog input signal into a digital signal includes a comparator configured to compare a reference signal with an input signal and, if the input signal matches the reference signal, inverts an output; a counter configured to count a comparison time of the comparator; a control circuit configured to monitor the output of the comparator; a voltage generating circuit configured to generate, if a monitoring result obtained by the control circuit indicates that the output of the comparator is at a predetermined level, a direct current voltage in accordance with the monitoring result; and an analog adder configured to add the voltage generated by the voltage generating circuit to the input signal and supply a sum signal to an input terminal of the comparator.

A 5GS/s voltage-to-time converter in 90nm CMOS

Abstract: A voltage-to-time converter (VTC) is presented for use in a time-based analog-to-digital converter (ADC). The converter runs with a 5 GHz input clock to provide a maximum conversion rate of 5 GS/s. A novel architecture enables the VTC to provide an adjustable linear delay versus input voltage characteristic. The circuit is realized in a 90nm CMOS process. After calibration, the converter achieves better than 3.7 effective bits for input frequencies up to 1.75 GHz, making it suitable for use in a time-based ADC with up to 4-bit resolution.