Showing papers on "Buck–boost converter published in 2001"

Switched reluctance motor drives : modeling, simulation, analysis, design, and applications

Abstract: PRINCIPLE OF OPERATION OF THE SWITCH RELUCTANCE MOTOR (SRM) Introduction Background Elementary Operation of the Switch Reluctance Motor Principle of Operation of the Switched Reluctance Motor Derivation of the Relationship Between Inductance and Rotor Position Equivalent Circuit SRM Configurations Linear Switched Reluctance Machines References DERIVATION OF SRM CHARACTERISTICS Introduction Data for Performance Computation Analytic Method for the Computation of Machine Characteristics Computation of Unaligned Inductance Computation of Aligned Inductance Computation of Inductance vs. Rotor Position vs. Excitation Current Comparison of Measured, Analytic and Finite Element Results References DESIGN OF SRM Introduction Derivation of Output Equation Selection of Dimensions Design Verification Operational Limit Selection of Number of Phases Selection of Poles Ratio of Pole-Arc to Pole-Pitch Selection of Pole Base Selection of Pole-Arcs Measurement of Inductance Calculation of Torque Design of Linear Switched Reluctance Machine (LSRM) References CHAPTER 4: CONVERTERS FOR SRM DRIVES Converter Configurations Asymmetric Bridge Converter Asymmetric Converter Variation Single Switch per Phase Converters m Switches and 2m Diodes m Switches and 2m Diodes with Independent Phase Current Control (m+1) Switch and Diode Configurations One Common Switch Configuration Minimum Switch Topology With Variable DC Link Variable DC Link Voltage with Buck Boost Converter Topology 1.5m Switches and Diodes Configuration Comparison of Some Power Converters Two Stage Power Converter Resonant Converter Circuits for Switched Reluctance Motor Drives References CONTROL OF SRM DRIVE Introduction Control Principle Closed Loop Speed Controlled SRM Drive Design of Current Controllers Flux Linkage Controller Torque Control Design of the Speed Controller References MODELING AND SIMULATION OF SRM DRIVE SYSTEM Introduction Modeling Simulation References ACOUSTIC NOISE AND ITS CONTROL IN SRM Introduction Sources of Acoustic Noise in Electrical Machines Noise Sources Noise Mitigation Qualitative Design Measures to Reduce Noise Measurement of Acoustic Noise and Vibrations Future Directions Appendix-1: Derivation of First Mode Frequency of SRM References SENSORLESS OPERATION OF SRM DRIVES Introduction Current Sensing Rotor Position Measurement Methods Rotor Position Estimation References APPLICATION CONSIDERATIONS AND APPLICATIONS Introduction Review of SRM Drive Features for Application Consideration Applications Emerging applications References

Control circuit and method for maintaining high efficiency in a buck-boost switching regulator

Abstract: A high efficiency control circuit for operating a buck-boost switching regulator is provided. The switching regulator can regulate an output voltage higher, lower, or the same as the input voltage. The switching regulator may be synchronous or non-synchronous. The control circuit can operate the switching regulator in buck mode, boost mode, or buck-boost mode. In buck mode, the switching regulator regulates an output voltage that is less than the input voltage. In boost mode, the switching regulator regulates an output voltage that is greater than the input voltage. In buck and boost modes, less than all of the switches are switched ON and OFF to regulate the output voltage to conserve power. In buck-boost mode, all of the switches switch ON and OFF to regulate the output voltage to a value that is greater than, less than, or equal to the input voltage.

A natural ZVS medium-power bidirectional DC-DC converter with minimum number of devices

Abstract: This paper introduces a new bidirectional, isolated DC-DC converter. A typical application for this converter can be found in the auxiliary power supply of hybrid electric vehicles. A dual half-bridge topology has been developed to implement the required power rating using the minimum number of devices. Unified zero-voltage switching was achieved in either direction of power flow with neither a voltage-clamping circuit nor extra switching devices and resonant components. All these new features allow high power density, efficient power conversion, and compact packaging. Complete descriptions of operating principle and design guidelines are provided in this paper. An extended state-space averaged model is developed to predict large- and small-signal characteristics of the converter in either direction of power flow. A 1.6-kW prototype has been built and successfully tested under full power. The experimental results of the converter's steady-state operation confirm the soft-switching operation, simulation analysis, and the developed averaged model. The proposed converter is a good alternative to full-bridge isolated bidirectional DC-DC converter in medium-power applications.

Buck-boost PWM converters having two independently controlled switches

Abstract: Single-switch step-up/step-down converters, such as the buck-boost, SEPIC and Cuk, have relatively high voltage and current stresses on components compared to the buck or the boost converter. A buck-boost converter with two independently controlled switches can work as a boost or as a buck converter depending on input-output conditions, and thus achieves lower stresses on components. Using the converter synthesis method from D. Zhou (1995), families of two-switch buck-boost converters are generated, including several new converter topologies. The two-switch buck-boost converters are evaluated and compared in terms of component stresses in universal-input power-factor-corrector applications. Among them, one new two-switch converter is identified that has low inductor conduction losses (50% of the boost converter), low inductor volt-seconds (72% of the boost converter), and about the same switch conduction losses and voltage stresses as the boost converter.

A fast dynamic DC-link power-balancing scheme for a PWM converter-inverter system

Abstract: The authors propose a new power converter control scheme for a converter-inverter system. The strategy is to fully utilize the inverter dynamics in controlling the converter dynamics. The authors obtain the power dynamics for both converter and inverter systems, and control the converter power so that it matches the required inverter power exactly. Then, in the ideal case, no power flows through the DC-link capacitors and, thus, the DC-link voltage does not fluctuate even though a very small amount of the DC-link capacitance is used. In forcing the converter power to match the inverter power, the authors utilize the master-slave control concept. They control the DC-link voltage level indirectly through the stored capacitor energy in order to exploit the advantage of the linear dynamic behavior of the capacitor energy. This helps them to circumvent a complex control method in regulating the DC-link voltage. Through simulation and experimental results, the superiority of the proposed converter control scheme is demonstrated.

Stacked multicell converter (SMC): properties and design

Abstract: We present in this paper a new topology of multilevel converter allowing an increase of input voltage level compared with the imbricated cells converter, while decreasing the stored energy in the converter. This new topology called SMC (stacked multicell converter) consists of a hybrid association of commutation cell making it possible to share the voltage constraint on several switches, and also to improve the output waveforms of the converter in terms of number of levels and switching frequency. After the introduction, the second part is devoted to the presentation of the topology. We give some explanation about the control of the SMC converter, and give some basics design properties for the SMC topology. Some simulation and experimental results obtained on a 50 kVA experimental set-up are presented.

Maximum power point tracking control of IDB converter supplied PV system

Abstract: The photovoltaic generator exhibits nonlinear V-I characteristics and its maximum-power point varies with solar insolation. An interleaved dual boost (IDB) converter is used to match the PV system to the load and to operate the solar cell array at maximum power point. A maximum power point tracking algorithm is developed using only load voltage information, eliminating array current detection. Analytical expressions for the PV array current and duty ratio of the converter corresponding to maximum power point operation of the solar cell array (SCA) are derived. SCA power output expressions with boost and interleaved dual boost converters are deduced. Load voltage based tracking effectiveness is demonstrated through simulation results. Experimental results validate the proposed method. Observations are also presented for partial shading conditions. The results obtained with this converter are compared with the boost converter PV system. It is demonstrated that the interleaved dual boost converter is more efficient and capable of reducing the ripple content in both source and load sides. As a result the interleaved dual boost converter photovoltaic systems require lower values of array input capacitance. SCA performance improves because of lower array ripple magnitudes.

Power factor correction circuit arrangement

Abstract: A power factor correction circuit arrangement. A rectified alternating-current (AC) input signal may be applied across inputs of a voltage converter circuit, such as a boost converter. Current drawn by the voltage converter may be sensed to form a first sensing signal that is representative of the current. The rectified input voltage may be converted to a second sensing signal that is representative of the AC input signal. Switching in the power converter is adjusted in a first feedback loop to equalize the first and second sensing signals and, thus, the current drawn is regulated to remain in phase with the AC input signal. A feedback signal adjusts switching so as to regulate the output voltage level of the voltage converter in a second feedback loop and, thus, controls power delivered to the load.

LLC series resonant DC-to-DC converter

Abstract: The present invention discloses a DC-to-DC converter. The DC-to-DC converter includes a square wave generator for generating a sequence of output voltages having a waveform of square wave. The DC-to-DC converter further includes a resonant tank connected to the square wave generator comprising a series capacitor connected to a series inductor and a parallel inductor. The DC-to-DC converter further includes a transformer having a primary side connected in series with the series inductor and connected in parallel to the parallel inductor. The transformer further includes a secondary side for connecting to a rectifying circuit for providing a rectified DC voltage to an output load circuit. The series capacitor functioning with the series inductor to provide a first characteristic resonant frequency represented by ƒ s , and the series capacitor functioning with the series inductor and the parallel inductor to provide a second characteristic resonant frequency represented by ƒ m wherein ƒ s >ƒ m . The converter runs at variable frequency switching to perform output regulation. The converter features high conversion efficiency at high input operation by switching at frequency between the first and second characteristic resonant frequency. In a preferred embodiment, the parallel inductor is integrated to transformer as primary magnetizing inductor and in further the series inductor may also be integrated into transformer.

Sample and hold method to achieve square-wave PWM current source for light emitting diode arrays

Abstract: An apparatus for controlling overshoots in the switching of LED arrays in a system having a switching voltage converter providing the biasing voltage for the LED array. By synchronizing a switching converter to an LED turn-on signal, loading on the voltage converter can be controlled such that output conduction of the converter only occurs when LEDs that are to be displayed are switched on to provide loading to the output of the converter. A Sample and hold method is employed to effectively store the current information in a previous “on” interval and use it for the current control in a following interval with inhibited current overshoot.

Symmetrical DC/DC converter

Abstract: A symmetrical DC/DC converter selects an energy transferring direction and a step-up or a step-down operation as well as a desired step-up or a step-down ratio. The converter includes a single inductor with a pair of switching devices connected to its terminals in a symmetrical arrangement with respect to the inductor. The converter is operable as a step-up converter and a step-down converter in a manner such that one and the other of the switching devices are used as an input switch and an output switch, respectively, and that one and the other of the switching devices are conversely used as an output switch and an input switch, respectively.

A new low-stress buck-boost converter for universal-input PPC applications

Abstract: In converters for power-factor-correction (PFC), universal-input capability (ability to operate from any AC line voltage, world-wide) comes with a heavy price in terms of component stresses and losses, size of components, and restrictions on the output DC voltage. A new two-switch topology is proposed to offer very significant performance improvements over the single-switch buck-boost converters (including flyback, SEPIC, and Cuk topologies) and conventional two-switch buck-boost cascaded converters. The proposed converter has buck-boost conversion characteristic, switch conduction losses comparable to the boost converter, no inrush current problem, and potential for smaller inductor size compared to the boost converter.

Range winding for wide input range front end DC/DC converter

Abstract: Hold up time requirement is a special requirement for a front end (FE) converter. The converter needs to provide output voltage within regulation for 20 ms after the AC input is lost. When designing the FE DC/DC converter, we want it to operate over a wide input range so that we can use less high voltage bus capacitor to meet the requirement. The converter efficiency is reduced at normal operating conditions, in order to cover wide input range. This paper demonstrates a new method to cover wide input range while also optimizing the normal condition operation with range winding.

Sensor and sigma-delta converter

Abstract: A sensor for determining at least one parameter with a sigma-delta converter ( 1 ) comprises switched input capacitors and feedback capacitors (Cf 1, Cf 2, Crefc 1, Crefc 2, Creff 1, Creff 2, Crt 1, Crt 2, Cr 1, Cr 2, Ctemp 1, Ctemp 2, Cs 1, Cs 2 ). At least one of the capacitors is designed such that its capacitance depends on the parameter to be determined. In this way, the change of capacitance can be directly determined by means of the sigma-delta converter. Due to a symmetric design of the converter a higher accuracy can be reached.

Maximum power tracking technique for solar panels

Abstract: The present invention provides an apparatus and method for tracking the maximum power point of a solar panel. A pulsewidth-modulated converter, for example a SEPIC or Cuk converter, is provided between the output of the panel and the load, and a perturbation is introduced into a switching parameter of the converter.

An improved boost PWM soft-single-switched converter with low voltage and current stresses

Abstract: This paper presents an improved regenerative soft turn-on and turn-off snubber applied to a boost pulsewidth-modulated (PWM) converter. The boost soft-single-switched converter proposed, which has only a single active switch, is able to operate with soft switching in a PWM way without high voltage and current stresses. This is achieved by using an auxiliary inductor, which is magnetically coupled with the main inductor of the converter. In order to illustrate the operating principle of this new converter, a detailed study, including simulations as well as experimental results, is carried out. The validity of this new converter is guaranteed by the obtained results.

Multi-phase switching converters and methods

Abstract: Multi-phase switching converters and methods that provide fast response and low ripple on the converter inputs and outputs. The converters include multiple converter stages that are normally operated in sequence into a common load. However upon sensing that operation of one of the converter stages does not bring the converter back into regulation, multiple converter stages are operated until regulation is reestablished, after which the converter stages are operated in sequence again. In the embodiment disclosed, upon sensing that operation of one of the converter stages does not bring the converter back into regulation, all converter stages are operated until regulation is reestablished, after which the converter stages are operated in sequence again starting with the stage with the lowest inductor current.

Primary side control circuit of a flyback converter

Abstract: Voltage feedback in flyback converters is typically done with the assistance of opto-couplers, to preserve electrical isolation. However the output voltage also exists (in part) across the primary side switch when in its off state. This paper investigates the extraction of the output voltage within one switching cycle. Good results are obtained from a flyback converter with a novel control circuit using cycle by cycle control. The converter works in both continuous and discontinuous mode of operation.

Flyback power converter with secondary-side control and primary-side soft switching

Abstract: A flyback power converter is described which provides multiple independently regulated outputs. Zero-volt primary side switching is achieved at a resonance minimum which occurs at the end of each energy cycle between a primary side capacitor and an isolation transformer primary winding.

The matrix converter drive performance under abnormal input voltage conditions

Abstract: The matrix converter is a direct frequency conversion device with high input power quality and regeneration capability. As a device without energy storage elements, it has higher power density than PWM inverter drives. However, for the same reason, the AC line side disturbances can degrade its performance and reliability. In this paper, the behavior of the matrix converter drive under abnormal input line voltage conditions has been investigated. A technique to eliminate the input current distortion due to the input voltage unbalance has been developed and its feasibility proven via computer simulations and laboratory experiments. The power line failure behavior has also been investigated and the rapid re-starting capability of the matrix converter drive has been demonstrated via laboratory experiments.

Power electronic circuits with all terminal currents non-pulsating

Abstract: Three terminal PWM DC to DC converter networks which accomplish both non-pulsating input and non-pulsating output currents using a single simple coupled inductor is revealed. The DC to DC converter networks accomplish buck, boost, buck boost (flyback), buck complement, boost complement, or flyback complement (SEPIC) conversion using a simple circuit requiring only two switches, one of which may be a simple diode rectifier, one or two capacitors, and three or four inductors, which may be co-located on a single common magnetic core. Also revealed are techniques to accomplish isolation, high order (quadrature) transfer functions, methodology for reducing current ripple to near zero levels at all terminals simultaneously, and methodology for generalizing the process of changing three terminal networks with pulsating terminal currents into three terminal networks with non-pulsating terminal currents.

Multiple output power supply including one regulated converter and at least one semi-regulated converter

Abstract: A power supply, including a regulated switchmode converter, a PWM controller, a semi-regulated converter, and a linear regulator. The regulated switchmode converter is for converting an input voltage to a first output voltage. The PWM controller is responsive to the first output voltage, and includes an output terminal coupled to a control terminal of a switch of the regulated switchmode converter. The semi-regulated switchmode converter is for converting the input voltage to an intermediate output voltage, and includes a switch having a control terminal coupled to the output terminal of the PWM controller. The linear regulator is coupled to the semi-regulated switchmode converter and is for converting the intermediate output voltage to a second output voltage.

Universal high efficiency power converter

Abstract: A universal power converter for generating a regulated voltage, current or power with a large input voltage range. The power converter has a voltage boost function configured to boost the rectified input voltage and provide power factor correction. The power converter also includes a voltage chop function to chop the boosted voltage to form an AC voltage. The power converter further includes at least one relay in electrical communication with the AC voltage and a transformer. The primary winding has at least two inputs operative to selectively vary the voltage generated on a secondary winding thereof selected by the relay. Accordingly, the power converter can generate different voltages at the output based upon the position of the relay and the boosted voltage. The power converter provides maximum power operation at a wide output voltage range, maximizing the charging energy.

Digital-to-analog converter and active matrix liquid crystal display

Abstract: A digital-to-analog converter comprises a first converter stage 1 for converting the m most significant bits of a k bit input signal to upper and lower voltage limits VL and VH by selecting the appropriate low impedance reference voltages. A second converter stage 2 performs a linear conversion of the n least significant bits of the k bit input within the voltage range defined by the voltage limits VL and VH. A precharging circuit comprising switches SW 1 and SW 2 disconnects the stage 2 from the load C LOAD , which is charged to the voltage limit VL during a precharge phase. The load is subsequently disconnected from the voltage limit VL and connected to the output of the stage 2 to complete charging of the load C LOAD to the converter output voltage.

Dynamically-controlled, intrinsically regulated charge pump power converter

Abstract: A charge pump power converter efficiently provides electrical power by dynamically controlling a switch matrix of the charge pump. Instead of open-loop oscillator-based control, a dynamic controller provides power upon demand by sensing the output voltage and changing the operating frequency of the charge pump in response. Moreover, this closed-loop dynamic control intrinsically voltage regulates the output voltage of the charge pump power converter without the inefficient addition of a step-down voltage regulator, downstream of the power converter. In addition, this closed-loop dynamic control allows for maintaining a desired output voltage even with variations in the input voltage. Also, the dynamic control accommodates the advantages of using ultra-capacitors in the charge pump. The power converter is capable of operating with a sub-one volt input voltage incorporating low-threshold, low on-resistance power MOSFET switches in the switch matrix of the charge pump. A progressive start-up circuit further allows the power converter to start from a discharged state even with a sub-one volt input voltage.

DC-DC converter and storage apparatus

Abstract: A DC-DC converter includes N capacitors having identical capacitances, initially coupled in series, and supplied with an external power supply voltage to be charged thereby, and an circuit for coupling the N capacitors in parallel and varying a duty ratio of a charging timing, so as to vary an internal power supply voltage which is output from the DC-DC converter.

Zero voltage switching cells for power converters

Abstract: Zero voltage switching cells using a small magnetic circuit element, a pair of switches, and a capacitor are revealed. The application of the zero voltage switching cells to any of a wide variety of hard switching power converter topologies yields equivalent power converters with zero voltage switching properties, without the requirement that the magnetizing current in the main magnetic energy storage element be reversed during each switching cycle. The new switching cells either provide integral line filtering or a means to accomplish zero voltage switching with no high side switch drive mechanism. In the subject invention the energy required to drive the critical zero voltage switching transition is provided by the small magnetic circuit element, either a single winding choke or a two winding coupled choke, that forms part of the zero voltage switching cell. The application of the zero voltage switching cells to buck, buck boost, Cuk, flyback, and forward converters is shown. A variation of the zero voltage switching cell which adds a single diode to clamp ringing associated with the magnetic circuit elements and parasitic capacitance of off switches is also revealed.

Input-current-shaper based on a modified SEPIC converter with low voltage stress

Abstract: The boost topology is often the designer's first choice when dealing with PFC front-ends. This topology is well documented in the literature and has obvious advantages like continuous input current and low voltage- and current-stress compared to other PFC topologies. The PFC SEPIC converter also has the advantage of the continuous input current but suffers from high voltage- and current stress. In this paper a modified SEPIC converter is presented with reduced voltage stress, comparable to that of the boost converter. Experimental result of a 200 W prototype for 185-270 V line voltage are also presented.

Parametric study of a resonant switched capacitor DC-DC converter

Abstract: The zero-current switching resonant switched capacitor DC-DC power converter is a new type of power converter, which has features of low weight, small volume, high efficiency, low EMI and feasibility of fabrication on a semiconductor IC chip. In this study, the authors focus on the parametric analysis of a double mode resonant switched capacitor converter proposed by Cheng in 1998. Since there exists great performance differences between ideal model and real circuits, in this work the authors propose a modified model by adding the resistance of circuit components. The modified model is then employed to study the circuit performance with respect to the loading effect and the variation of circuit parameters. Simulation results were found to be nearly in accordance with Cheng's experiment. In the paper, the average output voltage is explicitly expressed in terms of the so-called live time ratio, which provides a means of regulating the converter's output voltage.