Showing papers on "Boost converter published in 1998"
TL;DR: In this paper, a new method to set a predictive maintenance is presented and tested on two types of converters, i.e., sound electrolytic filter capacitors and a reference system including all the converter parameters was built for the converter at its sound state, and the lifetime of these capacitors was computed.
Abstract: Electrolytic filter capacitors are frequently responsible for static converter breakdowns. To predict these faults, a new method to set a predictive maintenance is presented and tested on two types of converters. The best indicator of fault of the output filter capacitors is the increase of ESR (equivalent series resistance). The output-voltage ripple /spl Delta/V/sub o/ of the converter increases with respect to ESR. In order to avoid errors due to load variations, /spl Delta/V/sub o/ is filtered at the switching frequency of the converter. The problem is that this filtered component is not only dependent on the aging of the capacitors, but also on the ambient temperature, output current, and input voltage of the converter. Thus, to predict the failure of the capacitors, this component is processed with these parameters and the remaining time before failure is deduced. Software was developed to establish predictive maintenance of the converter. The method developed is as follows. First, a reference system including all the converter parameters was built for the converter at its sound state, i.e., using sound electrolytic filter capacitors. Then, all these parameters were processed and compared on line to the reference system, thereby, the lifetime of these capacitors was computed.
346 citations
Patent•
31 Dec 1998
TL;DR: In this paper, the authors proposed a universal ballast control circuit that allows a universal discharge lamp to accommodate a gas discharge lamp within a relatively wide wattage range using a low-speed microcontroller.
Abstract: A universal ballast control circuit allows a universal ballast to accommodate a gas discharge lamp within a relatively wide wattage range using a low-speed microcontroller. The control circuit drives the ballast to start, run and dim a particular lamp type by providing a control voltage signal to a conventional inverter MOSFET driver to effect dynamic and selective changes in the duty cycle and the frequency of the inverter signal. In one aspect of the invention, the control circuit comprises a generator for generating a periodic analog voltage signal, a source for producing a DC voltage signal, a controller which includes a low-speed microcontroller for varying the frequency of the periodic analog voltage signal and the magnitude of the DC voltage signal, and a comparator for comparing the periodic analog voltage signal and the DC voltage signal to produce a control voltage signal. In another aspect of the invention, the control circuit comprises a generator for generating a periodic analog voltage signal, a controller for controlling the shape of the periodic analog voltage signal, and a comparator for comparing waveforms of the periodic analog voltage signal with the waveforms of two DC threshold voltages to generate a control signal. The present invention allows for the control circuit to be powered by a power supply signal either derived from an inverter half-bridge MOSFET driver, extracted from a boost inductor of the boost converter or generated by an appropriately configured dedicated miniature switch mode power supply. Finally, control circuit can be utilized to drive PFC circuity in a feedback configuration to regulate the level of boost converter output voltage signal.
234 citations
24 Apr 1998
TL;DR: In this paper, basic types of DC-DC converter topologies are studied to investigate their self-PFC capabilities, their input characteristics are compared and their input line current waveforms are predicted.
Abstract: Basic types of DC-DC converters, when operating in discontinuous conduction mode, have self power factor correction (PFC) property, that is, if these converters are connected to the rectified AC line, they have the capability to give higher power factor by the nature of their topologies. Input current feedback is unnecessary when these converters are employed to improve power factor. In this paper, basic types of DC-DC converter topologies are studied to investigate their self-PFC capabilities. Their input characteristics are compared and their input line current waveforms are predicted.
230 citations
22 Oct 1998
TL;DR: In this article, the need of a bi-directional DC to DC converter for a fuel cell system was described, and various combinations of current-fed and voltage-fed converters were explored for the application of different voltage levels.
Abstract: This paper first describes the need of a bi-directional DC to DC converter for a fuel cell system. Various combinations of current-fed and voltage-fed converters are explored for the application of different voltage levels. With a preliminary study, putting current-fed on low-voltage side and voltage fed on high voltage side indicated higher efficiency than the other way around. Two low-side circuit topologies were then selected for hardware implementation. One is the L-type half-bridge current-fed converter, and the other is full-bridge current-fed converter. The high-side circuit topology is fixed with a full-bridge voltage-fed converter. Two systems were built and tested to full power. The results indicate that the combination with the full-bridge converter on the low-voltage side is more efficient than the combination with the L-type half-bridge converter on the low-voltage side for both charging and discharging modes.
224 citations
15 Feb 1998
TL;DR: In this paper, the authors compared the buck-boost converter topologies for motoring and regenerative braking operation of a battery-fed DC motor drive with respect to the voltage level of the battery.
Abstract: The use of a bi-directional DC-DC converter in motor drives devoted to EVs allows a suitable control of both motoring and regenerative braking operations. In particular, during motoring operations of a battery-fed DC motor drive, a DC-DC converter is to be used to adjust the motor current in order to follow the torque reference signal. On the other hand, a bi-directional arrangement of the converter is needed for the reversal of the power flow, in order to recover the vehicle kinetic energy in the battery by means of motor drive regenerative braking operations. This paper deals with the study and comparison of two bi-directional buck-boost converter topologies. Each of them allows stepping the battery voltage level either up or down, according to motor drive modes of operation. For each converter topology computer simulations of modes of operation are presented together with experimental test results.
218 citations
TL;DR: In this article, a nonlinear model in the form of a mapping from one point of observation to the next has been derived, which has a closed form even when the parasitic elements are included.
Abstract: The occurrence of nonlinear phenomena like subharmonics and chaos in power electronic circuits has been reported recently. In this paper, the authors investigate these phenomena in the current-mode-controlled boost power converter. A nonlinear model in the form of a mapping from one point of observation to the next has been derived. The map has a closed form even when the parasitic elements are included. The bifurcation behavior of the boost power converter has been investigated with the help of this discrete model.
197 citations
Patent•
24 Dec 1998TL;DR: In this paper, a DC-to-DC power converter includes at least one power switch, a pulse width modulation circuit, an output inductor connected to the power switch and a current sensor connected in parallel with the inductor.
Abstract: A DC-to-DC power converter includes at least one power switch, a pulse width modulation circuit for generating control pulses for the at least one power switch, an output inductor connected to the at least one power switch, and a current sensor connected in parallel with the inductor for sensing current passing through the inductor. The current sensor preferably includes a resistor and a capacitor connected together in series. The current sensor is connected to a peak current control loop circuit cooperating with the pulse width modulation circuit for controlling the at least one power switch responsive to the current sensor. The resistor and capacitor preferably have respective values so that the current sensor is a substantially instantaneous current sensor. The output inductor has an inductance and a direct current (DC) resistance defining a first time constant. In one embodiment, the resistor and capacitor of the current sensor define a second time constant within a predetermined range of each other. In another embodiment, the resistor and capacitor of the current sensor define a second time constant substantially equal to the first time constant.
174 citations
12 Oct 1998
TL;DR: In this paper, a control method of reducing the size of the DC link capacitors of a power converter-inverter system was proposed, where information on the load power is incorporated in synthesizing the converter current control input so that a proper DC voltage level is maintained.
Abstract: This paper addresses a control method of reducing the size of the DC link capacitors of a power converter-inverter system. The main idea is to utilise the inverter operation status in the current control of the power converter. Specifically, information on the load power is incorporated in synthesizing the converter current control input so that a proper DC voltage level is maintained. The authors describe the dynamics of load current and apply feedback linearization theory to obtain an input output linearized system. Theoretically, this control strategy is effective in regulating the DC voltage level even though the DC link capacitor is arbitrarily small and load varies abruptly. The superior performance is demonstrated through simulation and experiment. Experiment was performed with a 9 kW PWM power converter-vector inverter system having a 75 /spl mu/F DC-link capacitor.
174 citations
TL;DR: In this article, a single-phase high-efficiency near-unity power-factor (PF) half-bridge boost converter circuit is presented with detailed analysis and design considerations for the power circuit using the fixed-band hysteresis current control (HCC) technique.
Abstract: A single-phase high-efficiency near-unity power-factor (PF) half-bridge boost converter circuit, which has been proposed earlier by other researchers, is presented with detailed analysis. This converter is capable of operating under variable PF. However, the focus of this paper is in achieving unity PF operation only. The efficiency of this circuit is high because there is only one series semiconductor on-state voltage drop at any instant. The existence of an imbalance in the voltages of the two DC-link capacitors, which was noted before, is confirmed here. The cause for the imbalance is analyzed using appropriate models, and a control method to eliminate it is discussed in detail. Analysis and design considerations for the power circuit using the fixed-band hysteresis current control (HCC) technique are provided. The analytical results are verified through simulation using switched and averaged circuit models of the scheme and also through experimental work. At 90-V AC input and 300-W 300-V output, the experimental prototype demonstrates an efficiency of 96.23% and a PF of 0.998. This converter, with its relatively high DC-output voltage, is well suited for the 110-V utility supply system. A circuit modification for universal input voltage range operation is also suggested.
174 citations
TL;DR: A 750 W 80 kHz prototype of the boost ZVT-PWM converter has been built in the laboratory to experimentally verify the analysis and a detailed design procedure of the proposed active snubber cell is also presented in this paper.
Abstract: An active snubber cell is proposed to contrive zero-voltage-transition (ZVT) pulsewidth-modulated (ZVT-PWM) converters. Except for the auxiliary switch, all active and passive semiconductor devices in a ZVT-PWM converter operate at zero-voltage-switching (ZVS) turn on and turn off. The auxiliary switch operates at ZVS turn off and near zero current-switching (ZCS) turn on. An analytical study on a boost ZVT-PWM converter with the proposed active snubber cell is presented in detail. A 750 W 80 kHz prototype of the boost ZVT-PWM converter has been built in the laboratory to experimentally verify the analysis. Six basic ZVT-PWM converters can be easily created by attaching the proposed active snubber cells to conventional PWM converters. A detailed design procedure of the proposed active snubber cell is also presented in this paper.
174 citations
Book•
01 Jan 1998
TL;DR: In this paper, the authors present an analytical solution to calculate the current waveform of an AC-to-AC converter and demonstrate the effect of current waveforms on the performance of the converter.
Abstract: Preface. 1 Principles and Methods of Electric PowerConversion. 1.1 What Is Power Electronics? 1.2 Generic Power Converter. 1.3 Waveform Components and Figures of Merit. 1.4 Phase Control. 1.5 Pulse Width Modulation. 1.6 Calculation of Current Waveforms. 1.6.1 Analytical Solution. 1.6.2 Numerical Solution. 1.6.3 Practical Examples: Single-Phase Diode Rectifiers. 1.7 Summary. Example. Problems. Computer Assignments. Literature. 2 Semiconductor Power Switches. 2.1 General Properties of Semiconductor Power Switches. 2.2 Power Diodes. 2.3 Semicontrolled Switches. 2.3.1 SCRs. 2.3.2 Triacs. 2.4 Fully Controlled Switches. 2.4.1 GTOs. 2.4.2 IGCTs. 2.4.3 Power BJTs. 2.4.4 Power MOSFETs. 2.4.5 IGBTs. 2.5 Comparison of Semiconductor Power Switches. 2.6 Power Modules. 2.7 Summary. Literature. 3 Supplementary Components and Systems. 3.1 What Are Supplementary Components and Systems? 3.2 Drivers. 3.2.1 Drivers for SCRs, Triacs, and BCTs. 3.2.2 Drivers for GTOs and IGCTs. 3.2.3 Drivers for BJTs. 3.2.4 Drivers for Power MOSFETs and IGBTs. 3.3 Overcurrent Protection Schemes. 3.4 Snubbers. 3.4.1 Snubbers for Power Diodes, SCRs, and Triacs. 3.4.2 Snubbers for GTOs and IGCTs. 3.4.3 Snubbers for Transistors. 3.4.4 Energy Recovery from Snubbers. 3.5 Filters. 3.6 Cooling. 3.7 Control. 3.8 Summary. Literature. 4 AC-to-DC Converters. 4.1 Diode Rectifiers. 4.1.1 Three-Pulse Diode Rectifier. 4.1.2 Six-Pulse Diode Rectifier. 4.2 Phase-Controlled Rectifiers. 4.2.1 Phase-Controlled Six-Pulse Rectifier. 4.2.2 Dual Converters. 4.3 PWM Rectifiers. 4.3.1 Impact of Input Filter. 4.3.2 Principles of Pulse Width Modulation. 4.3.3 Current-Type PWM Rectifier. 4.3.4 Voltage-Type PWM Rectifier. 4.4 Device Selection for Rectifiers. 4.5 Common Applications of Rectifiers. 4.6 Summary. Examples. Problems. Computer Assignments. Literature. 5 AC-to-AC Converters. 5.1 AC Voltage Controllers. 5.1.1 Phase-Controlled Single-Phase AC Voltage Controller. 5.1.2 Phase-Controlled Three-Phase AC Voltage Controllers. 5.1.3 PWM AC Voltage Controllers. 5.2 Cycloconverters. 5.3 Matrix Converters. 5.4 Device Selection for AC-to-AC Converters. 5.5 Common Applications of AC-to-AC Converters. 5.6 Summary. Examples. Problems. Computer Assignments. Literature. 6 DC-to-DC Converters. 6.1 Static DC Switches. 6.2 Step-Down Choppers. 6.2.1 First-Quadrant Chopper. 6.2.2 Second-Quadrant Chopper. 6.2.3 First-and-Second-Quadrant Chopper. 6.2.4 First-and-Fourth-Quadrant Chopper. 6.2.5 Four-Quadrant Chopper. 6.3 Step-Up Chopper. 6.4 Current Control in Choppers. 6.5 Device Selection for Choppers. 6.6 Common Applications of Choppers. 6.7 Summary. Example. Problems. Computer Assignments. Literature. 7 DC-to-AC Converters. 7.1 Voltage-Source Inverters. 7.1.1 Single-Phase Voltage-Source Inverter. 7.1.2 Three-Phase Voltage-Source Inverter. 7.1.3 Voltage Control Techniques for Voltage-SourceInverters. 7.1.4 Current Control Techniques for Voltage-SourceInverters. 7.2 Current-Source Inverters. 7.2.1 Three-Phase Square-Wave Current-Source Inverter. 7.2.2 Three-Phase PWM Current-Source Inverter. 7.3 Multilevel Inverters. 7.4 Soft-Switching Inverters. 7.5 Device Selection for Inverters. 7.6 Common Applications of Inverters. 7.7 Summary. Examples. Problems. Computer Assignments. Literature. 8 Switching Power Supplies. 8.1 Basic Types of Switching Power Supplies. 8.2 Nonisolated Switched-Mode DC-to-DC Converters. 8.2.1 Buck Converter. 8.2.2 Boost Converter. 8.2.3 Buck Boost Converter. 8.2.4 uk Converter. 8.2.5 SEPIC and Zeta Converters. 8.2.6 Comparison of Nonisolated Switched-Mode DC-to-DCConverters. 8.3 Isolated Switched-Mode DC-to-DC Converters. 8.3.1 Single-Switch Isolated DC-to-DC Converters. 8.3.2 Multiple-Switch Isolated DC-to-DC Converters. 8.3.3 Comparison of Isolated Switched-Mode DC-to-DCConverters. 8.4 Resonant DC-to-DC Converters. 8.4.1 Quasi-Resonant Converters. 8.4.2 Load-Resonant Converters. 8.4.3 Comparison of Resonant DC-to-DC Converters. 8.5 Summary. Examples. Problems. Computer Assignments. Literature. 9 Power Electronics and Clean Energy. 9.1 Why Is Power Electronics Indispensable in Clean EnergySystems? 9.2 Solar and Wind Renewable Energy Systems. 9.2.1 Solar Energy Systems. 9.2.2 Wind Energy Systems. 9.3 Fuel Cell Energy Systems. 9.4 Electric and Hybrid Cars. 9.5 Power Electronics and Energy Conservation. 9.6 Summary. Literature. Appendix A PSpice Simulations. Appendix B Fourier Series. Appendix C Three-Phase Systems. Index.
TL;DR: In this article, a three-phase multilevel converter with separately regulated DC power supplies is presented, where the DC voltages are provided by medium-frequency DC-DC converters.
Abstract: A new converter topology for drives is presented in this paper: a three-phase multilevel converter with separately regulated DC power supplies. The DC voltages are provided by medium-frequency DC-DC converters. The applications for the converter are especially high-power traction systems, where the voltage applied to the induction motor is bigger than 1 kV. The motor current is of a very high quality, compared to a classical three-phase converter. This allows keeping the switching frequency low by using phase-shifted pulsewidth modulation (PWM) carriers. Different modulation methods have been developed and simulated. Experimental tests have been made on a 12 kW prototype.
TL;DR: In this paper, measurements of conducted and radiated electromagnetic interference (EMI) emission from hard-switched and softswitched buck, boost, and flyback converters of similar power ratings are presented.
Abstract: Measurements of conducted and radiated electromagnetic interference (EMI) emission from hard-switched and soft-switched buck, boost, and flyback converters of similar power ratings are presented. Results indicate that EMI emission can be substantially reduced by using a soft-switching technique in power converters. Thus, the soft-switching technique provides a practical and useful solution to reduce EMI emission from switched-mode power circuits. A comparison of EMI emission on the three classes of converters is also included. The flyback converter is found to be the least EMC friendly among the converters tested.
17 May 1998
TL;DR: In this paper, a new family of DC-to-DC converters featuring clamping action, PWM modulation and soft-switching in both active and passive switches, is proposed to overcome the limitations of clamped mode DC to DC converters.
Abstract: A new family of DC-to-DC converters featuring clamping action, PWM modulation and soft-switching (ZVS) in both active and passive switches, is proposed to overcome the limitations of clamped mode DC-to-DC converters. The new family of converters is generated and the new circuits are presented. As the resonant circuits absorb all parasitic reactances, including transistor output capacitance and diode junction capacitance, these converters are suitable for high-frequency operation. Principle of operation of the boost converter, theoretical analysis, simulation and experimental results are presented, taken from a laboratory prototype rated at 1600 W, input voltage of 300 V, output voltage of 400 V, and operating at 100 kHz. The measured efficiency at full load was 98%.
TL;DR: Experimental results from a 2 kVA IGBT-based prototype showing good system dynamic performance are presented, and three solutions for the DC voltage control are presented.
Abstract: A PWM voltage rectifier has useful characteristics on its DC and AC sides. On its DC side, a DC-link unidirectional voltage is obtained and bidirectional power transfer capability is possible by reversing the flow direction of the DC-link current. On its AC side, near sinusoidal current waveforms and AC four-quadrant operation can be obtained, leading to high-quality power being exchanged between the power converter and the mains. The use of AC filters becomes unnecessary. The rectifier DC voltage must be regulated to a constant value. In this paper, three solutions for the DC voltage control are presented. In the first solution, the DC voltage is controlled by acting upon the quadrature component of the power converter fundamental Park's voltages with relation to the mains voltages. Slow responses are necessary because of stability reasons. Also, load power variations produce both active and reactive power variations in the power converter AC side. To improve the DC voltage response, a second control solution is presented. The power converter currents in Park's coordinates must be controlled. The DC voltage is controlled by controlling the direct Park's current component and, thus, acting only on the active power of the converter AC side. Faster responses are achieved. In this case, load power variations do not produce reactive power variations in the converter AC side. The third control solution is a simplified version of this last one. Experimental results from a 2 kVA IGBT-based prototype showing good system dynamic performance are presented.
Patent•
05 Jun 1998TL;DR: In this paper, a zero current detector capable of detecting both forward and reverse zero current points facilitates the compensation of parasitic capacitance and parasitic oscillations is presented, which is well suited to integration with an inexpensive digital controller such as a microprocessor.
Abstract: A method and apparatus for controlling a boost converter, which offers improved power factor correction by compensating for the distorting effects of parasitic capacitance and parasitic oscillations. By precise adjustments to the closing time of the boost switch, the effects of parasitic capacitance can be reduced or eliminated. A zero current detector capable of detecting both forward and reverse zero current points facilitates the compensation. The method and circuit of the present invention are well-suited to integration with an inexpensive digital controller such as a microprocessor, and a method of dithering to enhance the time resolution of clocked digital circuits is presented.
TL;DR: An alternative approach to modeling pulsewidth-modulated (PWM) DC/DC converters out of basic converter units (BCUs) is presented and can yield the same small-signal models as those derived from the direct state-space averaging method.
Abstract: An alternative approach to modeling pulsewidth-modulated (PWM) DC/DC converters out of basic converter units (BCUs) is presented in this paper. Typical PWM DC/DC converters include the well-known buck, boost, buck-boost, Cuk, Zeta, and Sepic. With proper reconfiguration, these converters can be represented in terms of either buck or boost converter and linear devices, thus, the buck and boost converters are named BCUs. The PWM converters are, consequently, categorized into buck and boost families. With this categorization, the small-signal models of these converters are readily derived in terms of h parameter (for buck family) and g parameter (for boost family). Using the proposed approach, not only can one find a general configuration for converters in a family, but one can yield the same small-signal models as those derived from the direct state-space averaging method. Additionally, modeling of quasi-resonant converters and multiresonant converters can be simplified when adopting the proposed approach.
Patent•
TDK1
TL;DR: In this article, a plurality of converter circuits A and B are provided, and the output ends of the output rectifier smoothing circuits 7 and 8 are connected commonly, with the two ends connecting between the connecting point of switching elements 11 and 12 and one end of a source 10.
Abstract: A plurality of converter circuits A and B are provided. The converter circuits A and B have circuit structures that are identical to each other. In the converter circuit A, a resonant capacitor 31, a resonant inductor 32 and a primary winding 51 of a transformer 5 are connected in series, with the two ends of the serial circuit thus achieved connected between the connecting point of switching elements 11 and 12 and one end of a source 10. The output ends of output rectifier smoothing circuits 7 and 8 are connected commonly. Resonant circuits 3 and 4 of the converter circuits A and B are connected with each other.
TL;DR: In this paper, a single-stage electronic ballast with a dimming feature and a unity power factor is proposed, which is suitable for applications with moderate power level and low-line voltage while requiring a high-output voltage.
Abstract: Analysis, design, and practical consideration of a single-stage electronic ballast with dimming feature and unity power factor are presented in this paper. The proposed single-stage ballast is the combination of a boost converter and a half-bridge series-resonant parallel-loaded inverter. The boost semistage working in the discontinuous conduction mode functions as a power factor corrector and the inverter semistage operated above resonance are employed to ballast the lamp. Replacing the lamp with the plasma model, analysis of the ballast is fulfilled. The dimming feature is carried out by pulse-width modulation (PWM) and variable-frequency controls simultaneously. The proposed single-stage ballast is suitable for applications with moderate power level and low-line voltage while requiring a high-output voltage. It can save a controller, an active switch and its driver, reduce size, and possibly increase system reliability while requiring two additional diodes over a conventional two-stage system. A prototype was implemented to verify the theoretical discussion. The hardware measurements have shown that the desired performance can be achieved feasibly.
04 Oct 1998
TL;DR: In this article, the buck-boost type two-input DC-DC converter is used to combine the several input power sources and to supply the regulated output voltage for the load.
Abstract: Recently, clean electric power generation systems have attracted a great deal of social attention to exploit clean energy resources such as solar arrays, wind generators, fuel cells, etc. In this case, the multiple-input DC-DC power converter is useful to combine the several input power sources and to supply the regulated output voltage for the load. The novel solar cell power supply system using the buck-boost type two-input DC-DC converter is proposed, in which the solar array and the commercial AC line are exploited as power sources and they are combined by the two input windings of the energy-storage reactor. Also, its operation principle and performance characteristics are discussed. Furthermore, the solar cell optimum operating point tracker is proposed and examined. It is confirmed by the experiment that the proposed solar cell power supply system has the excellent performance characteristics.
15 Feb 1998
TL;DR: In this article, a new input current shaper is proposed based on the connection of a voltage source and a loss-free resistor (LFR) between the input rectifier and the bulk capacitor in a conventional switchingmode power supply with no power factor correction.
Abstract: A new input current shaper is proposed in this paper. The operating principle is based on the connection of a voltage source and a loss-free resistor (LFR) between the input rectifier and the bulk capacitor in a conventional switching-mode power supply with no power factor correction. Both the voltage source and the LFR are obtained as an additional output from the power converter's transformer. This additional output is a forward-type scheme with one extra inductor. With the final topology, a good tradeoff between capacitor voltage, re-cycling energy and harmonic content can be established in order to comply with IEC 1000-3-2 at different power levels.
15 Feb 1998
TL;DR: In this article, a DC-DC power converter for use with low voltage microprocessor loads is described, and the control method is a hysteretic current-mode control in the continuous conduction mode which has fast transient response.
Abstract: The paper describes a DC-DC power converter for use with low voltage microprocessor loads. The control method is a hysteretic current-mode control in the continuous conduction mode which has fast transient response. At light loads, the power converter operates in the discontinuous conduction mode using a peak current control method which causes the switching frequency to be proportional to load current, thus maintaining high efficiency in a very wide range of loads. The control method implementation, transient response and output inductor design equations, and equations for designing an input filter to reduce input current di/dt are provided. An inductor current estimator which provides higher efficiency, good transient response, and current limiting, is presented. Experimental results for a 5.0 V input, 3.1 V output, 13 A DC-DC converter are included to verify the theoretical information.
17 May 1998
TL;DR: In this paper, the effect of dead time delays on the efficiency of a 1 MHz low voltage, synchronous buck power converter was investigated and the overall efficiency was calculated as a function of the load current and the switching frequency with the dead time as a parameter.
Abstract: The effect of dead time delays on the efficiency of a constant frequency, 1 MHz low voltage, synchronous buck power converter is investigated. The overall efficiency is calculated as a function of the load current and the switching frequency with the dead time as a parameter. It was calculated, and subsequently experimentally verified, that the efficiency can be improved by over 3.5% by eliminating unnecessary body diode conduction.
TL;DR: A passive lossless snubber cell is proposed to improve the turn-on and turnoff transients of the MOSFETs in nonisolated pulsewidth modulated (PWM) DC/DC converters.
Abstract: A passive lossless snubber cell is proposed to improve the turn-on and turnoff transients of the MOSFETs in nonisolated pulsewidth modulated (PWM) DC/DC converters. Switching losses and EMI noise are reduced by restricting di/dt of the reverse-recovery current and dv/dt of the drain-source voltage. The MOSFET operates at zero-voltage-switching (ZVS) turnoff and near zero-current-switching (ZCS) turn-on. The freewheeling diode is also commutated under ZVS. As an example, operation principles, theoretical analysis, relevant equations, and experimental results of a boost converter equipped with the proposed snubber cell are presented in detail. Efficiency of 96% has also been measured in the experimental results reported for a 1 kW 100 kHz prototype in the laboratory, Six basic nonisolated PWM DC/DC converters (buck, boost, buck-boost, Cuk, Sepic, and Zeta) equipped with the proposed general snubber cells are also shown in this paper.
17 May 1998
TL;DR: In this article, a simple control method is presented for a single-stage single-switch isolated power-factor-correction (PFC) regulator that can simultaneously achieve unity power factor and fast output voltage regulation while keeping the voltage stress of the storage capacitor low.
Abstract: In this paper, a simple control method is presented for a single-stage single-switch isolated power-factor-correction (PFC) regulator that can simultaneously achieve unity power factor and fast output voltage regulation while keeping the voltage stress of the storage capacitor low. The converter topology comprises essentially a cascade combination of a discontinuous-mode boost converter and a continuous-mode forward converter. The proposed control utilizes variation of both duty cycle and frequency. The role of varying the duty cycle is mainly to regulate the output voltage. Changing the frequency, moreover, can achieve unity power factor as well as low-voltage stress. Basically, the switching frequency is controlled such that it has a time periodic component superposed on top of a static value. While the time periodic component removes the harmonic contents of the input current, the static value is adjusted according to the load condition so as to maintain a sufficiently low-voltage stress across the storage capacitor. The theory is first presented which shows the possibility of meeting all three requirements using a combined duty cycle and frequency control. An experimental prototype circuit is presented to verify the controller's functions.
21 Sep 1998
TL;DR: In this paper, a new improved boost topology is proposed to reduce the input current ripple, which is realized by adding an extra LC circuit with coupled inductors to the conventional topology.
Abstract: A new improved boost topology is proposed to reduce the input current ripple. The new topology is realized by adding an extra LC circuit with coupled inductors to the conventional boost topology. The operating principle and the small-signal characteristics are analyzed. Comparisons are made between the proposed improved topology and the conventional boost topology. An experimental converter has been built and tested to verify the theoretical analysis.
Patent•
16 Jul 1998
TL;DR: In this paper, an EL lamp is driven by a power supply including a voltage boost circuit and a low power inverter, and the boost circuit includes a level shifting capacitor to provide voltage doubling.
Abstract: An EL lamp is driven by a power supply including a voltage boost circuit and a low power inverter. The boost circuit includes a level shifting capacitor to provide voltage doubling. The inverter includes an inductor and at least one transistor connected in series between the output of the boost circuit and ground.
TL;DR: In this paper, two nonconventional HVDC converter arrangements are compared: the capacitor commutated converter (CCC) in which series capacitors are included between the converter transformer and the valves, and the controlled series capacitor converter (CSCC), based on more conventional topology.
Abstract: Two nonconventional HVDC converter arrangements are compared. These include the capacitor commutated converter (CCC) in which series capacitors are included between the converter transformer and the valves, and the controlled series capacitor converter (CSCC), based on more conventional topology, in which series capacitors are inserted between the AC filter bus and the AC network. Results show that both options have comparable steady state and transient performance. Danger of ferroresonance with the CSCC option is eliminated by controlling the amount of series compensation.
TL;DR: The generalized state-space averaging (GSSA) as discussed by the authors was proposed for the analysis of a class of periodically switched networks, where the switching frequency must be much higher than the highest natural frequency of the networks, while the input variables can be bounded fast timevarying functions.
Abstract: A unified averaging technique, here called the generalized state-space averaging (GSSA) technique, for the analysis of a class of periodically switched networks is proposed in the present paper. The basic assumption of GSSA is that the switching frequency must be much higher than the highest natural frequency of the networks, while the input variables can be bounded fast time-varying functions. It is shown in this paper that the GSSA approach generalizes the idea of the averaging technique to overcome the limitations of the conventional state-space averaging method, which prevents us from applying it to quasi-resonant converters (QRCs). The application of GSSA to the analysis of QRCs has been illustrated via examples of the zero-current switching QRC buck converter and zero-voltage switching QRC boost converter. Its accuracy has been verified by numerical simulation and experimental results.
17 May 1998
TL;DR: In this paper, six existing methods for modeling PWM converters in discontinuous conduction mode (DCM) are reviewed and a new method is presented that leads to either the conventional reduced-order model or a new fullorder model, depending on how the duty-ratio constraint is derived.
Abstract: Six existing methods for modeling PWM converters in discontinuous conduction mode (DCM) are reviewed. They are classified as either reduced-order or full-order model methods, and the methods in each group are shown to produce exactly the same averaged models. Using the concept of duty-ratio constraints, a new method is presented that leads to either the conventional reduced-order model or a new full-order model, depending on how the duty-ratio constraint is derived. With a boost converter as an example, the new full-order averaged model is shown to be more accurate than previously published models.