Showing papers on "Boost converter published in 1997"

A novel three-phase utility interface minimizing line current harmonics of high-power telecommunications rectifier modules

Abstract: Based on the combination of a three-phase diode bridge and a DC/DC boost converter, a new three-phase three-switch three-level pulsewidth modulated (PWM) rectifier system is developed. It can be characterized by sinusoidal mains current consumption, controlled output voltage, and low-blocking voltage stress on the power transistors. The application could be, e.g., for feeding the DC link of a telecommunications power supply module. The stationary operational behavior, the control of the mains currents, and the control of the output voltage are analyzed. Finally, the stresses on the system components are determined by digital simulation and compared to the stresses in a conventional six-switch two-level PWM rectifier system.

A bi-directional DC-DC converter topology for low power application

Abstract: This paper presents a bidirectional DC-DC converter for use in low power applications. The proposed topology is based on a half-bridge on the primary and a current-fed push-pull on the secondary side of a high frequency isolation transformer. Achieving bidirectional flow of power using the same power components provides a simple, efficient and galvanically isolated topology that is specially attractive for use in battery charge/discharge circuits in DC UPS. The DC mains (provided by the AC mains), when presented, powers the down stream load converters and the bidirectional converter which essentially operates in the buck mode to charge the battery to a nominal value of 48 V. On failure of the DC mains (derived from the AC mains), the converter operation is comparable to that of a boost and the battery regulates the bus voltage and thereby provides power to the downstream converters. Small signal and steady state analyses are presented for this specific application. The design of a laboratory prototype is included. Experimental results from the prototype, under different operating conditions, validate and evaluate the proposed topology. An efficiency of 86.6% is achieved in the battery charging mode and 90% when the battery provides load power. The converter exhibits good transient response under load variations and switchover from one mode of operation to another.

Single-phase matrix converter

Abstract: A topology of a single-phase AC/AC direct power converter is presented. The circuit, composed from four ideal power switches, is used as a frequency step-up converter. The equations of the proposed converter are developed, its switching angle pattern is calculated and the dynamic behaviour of the system is simulated. Using a power MOSFET and four Schottky diodes, the basic power switch is assembled and a power converter fed from 50 V (RMS), 50 Hz, supplying a passive R, L load operated at 100 Hz, was constructed. Satisfactory agreement between simulated and laboratory results was observed.

H/sup /spl infin// control applied to boost power converters

Abstract: The controller in a pulse-width-modulation (PWM) power converter has to stabilize the system and guarantee an almost constant output voltage in spite of the perturbations in the input voltage and output load over as large a bandwidth as possible. Boost and flyback power converters have a right-half-plane zero (RHPZ) in their transfer function from the duty cycle to the output voltage, which makes it difficult to achieve the aforementioned goals. Here, the authors propose to design a controller using H/sup /spl infin// control theory, via the solution of two algebraic Riccati equations. The almost optimal H/sup /spl infin// controller is of the same order as the converter and has a relatively low DC gain. The closed-loop characteristics of a typical low-power boost power converter with four different control schemes were compared by computer simulation. The H/sup /spl infin// control was found to be superior in a wide frequency range, while being outperformed by the others at extremely low frequencies. Good agreement was found between simulation results and experimental measurements.

Single-stage, single-switch, isolated power supply technique with input-current shaping and fast output-voltage regulation for universal input-voltage-range applications

Abstract: A new single-stage, single-switch, input-current shaping (S/sup 4/ICS) technique which combines the boost-like input-current shaper with a continuous-conduction-mode DC/DC output stage is described. In this technique, the boost inductor can operate in both the discontinuous and continuous conduction modes. Due to the ability to keep a relatively low voltage (<450 Vdc) on the energy-storage capacitor, this technique is suitable for the universal line voltage applications. The voltage on the energy-storage capacitor is kept within the desirable range by the addition of two transformer windings. The principle of operation of the S/sup 4/ICS circuit with forward DC/DC converter is presented. Experimental results obtained on a 100-W (5-V/20-A) prototype circuit are also given.

Optimised input filter design and low-loss switching techniques for a practical matrix converter

Abstract: The matrix converter permits frequency conversion in a single-stage process. The perceived disadvantage of the matrix converter is that conduction losses are high. However, semisoft current commutation and optimal sequence switching can be used to minimise commutation losses so that at high switching frequencies the total losses in the matrix converter can be less than those in a conventional rectifier–inverter combination. The viability of the matrix converter depends to a large extent on the size and cost of the input filter components required to meet international power quality standards. In the paper filter designs are examined and guidelines established. Practical tests have been carried out on a 3.5 kW converter to validate computer models. It is concluded that the matrix converter is viable if the right combination of semiconductor switching techniques and input filter design are employed.

Super capacitor battery clone

Abstract: An aircraft electrical supply bus supplementing arrangement in which electrical energy is stored in a large capacitor and energy flow between the capacitor and the bus is controlled by a bi-directional electrical converter circuit of the switched inductance type. The varying terminal voltage of the energy storing capacitor, a super capacitor, is coupled to the relatively fixed voltage of the aircraft supply bus by way of the voltage changing capability of the converter circuit switched inductance. Current flow levels in this inductance are controlled with a negative feedback regulator circuit. Energy storage efficiency in the converter is enhanced with respect to weight and physical size of the capacitor element by ability of the converter circuit to accept a widely varying input voltage while generating a relatively constant output voltage. Suppression of electrical transients and improved regulation of voltage on the aircraft energy supply bus especially at distal and bus impedance-isolated locations are achieved.

Method and system for wind turbine braking

Abstract: Stored rotational energy in an operating variable speed wind turbine is used to pitch blades and brake the wind turbine in the event of utility power grid failure. In one embodiment, a generator IGBT converter and the main power utility grid IGBT converter supply control and pitch servo power during turbine deceleration, and a ride-through capacitor on a DC emergency power supply bus and the main DC link capacitor provide additional energy storage. In another embodiment, a step-down DC/DC power converter adds to the intermediate DC link of the power conversion system with the secondary of the step down converter powering both the hub pitch controller and the wind turbine control system.

DC/AC power converter

Abstract: A DC link power converter apparatus including a first DC to DC converter, a DC to AC converter and a load balancing storage element. The first DC to DC converter has first and second DC ports and the DC to AC converter has a third DC port and has an AC port. The first DC port is connectable to a DC source and the second DC port is connected to the third DC port. The AC port is connectable to an AC load. The load balancing energy storage element is connected to the second DC port for decoupling the DC to DC converter from the DC to AC converter by supplying energy to the third DC port when a voltage at the second DC port is tending to decrease and for storing energy received from the second DC port when a voltage at the third port is tending to increase.

Single inductor multiple output boost regulator

Abstract: The present invention provides two or more output voltages from one input voltage and one inductor. Each output voltage is formed by a switch controlling the charge delivered to each of the corresponding output capacitors. Preferably, a diode is placed in series with each switch that controls the charging of the output capacitors to prevent any extraneous stray current from escaping while the switch is closed. The controller utilizes pulse width modulation to deliver the correct amount of energy to each load and to synchronize the order of energy delivery to each load. The use of one input voltage and one inductor for charging multiple output voltages simplifies the complexity of the circuit of the present invention and eliminates the need for a single inductor dedicated to each load. Further, the predetermined output voltage level for each load can be changed without modifying the passive elements in the circuit. Rather, the predetermined voltage level for each load is changed by re-programming the controller thereby modifying the duration and frequency of the pulse received by the respective load from the charging inductor.

A single-switch AC/DC converter with power factor correction

Abstract: A new single-stage, single-switch power factor correction converter with output electrical isolation is proposed in this paper. The topology of this converter is derived by combining a boost circuit and a forward circuit in one power stage. To improve the performance of the AC-DC converter (i.e., good power factor correction, low total harmonic distortion (THD) and low DC bus voltage), two bulk storage capacitors are adopted. Its excellent line regulation capability makes the converter suitable for universal input application. Due to its simplified power stage and control circuit, this converter presents a better efficiency, lower cost and higher reliability. Detailed steady state analysis and design procedure are presented. To verify the performance of the proposed converter, a design example along with P-simulation program with integrated circuit emphasis (PSPICE) simulation and experimental implementation are given. The measured power factor and efficiency are 99% and 87% at low line (i.e. 110 VAC) operation, and 95% and 81% at high line (i.e. 220 VAC) operation, respectively.

Portable power system using DC to DC converter

Abstract: A portable power system for a hand tool employs a high-voltage transmission of power from a battery pack over a cord to a DC to DC converter, which steps the transmission voltage down to rated tool voltage. The system uses a switching transistor to transmit power according to a duty cycle which varies automatically according to tool current draw and voltage. The DC to DC converter employs synchronous rectification with an inductor-capacitor network to transform a duty cycle square wave into DC power. The startup voltage sense feature permits powering up the converter circuitry only when needed. The converter will shut down if no current has been drawn by the tool for a predetermined period of time or if the converter unit is in danger of overheating, as determined by a stored algorithm. The portable power system has safeguards to prevent fouling or shorting in wet environments, is adaptable to left or right handed users, and is physically configurable into a variety of carrying modes.

System and method for reducing power losses by gating an active power factor conversion process

Abstract: A power supply includes a power factor correction converter and a controller that disables a power factor correction converter when the power supply is operating in a low power mode, when the power factor correction converter is not needed. The controller of the power factor correction converter performs control operations as directed by a control program executing in a computer or processor in some embodiments. In other embodiments, the control operations are directed by an automatic sequence self-directed by a state machine or other sequencer according to a self-analysis.

A multi-resonant converter for non-contact charging with electromagnetic coupling

Abstract: A parallel resonant power converter (PRC-LLCC) is analyzed for automatic inductive charging applications. The tank circuit of this power converter consists of a leakage inductance, a magnetizing inductance and two power capacitors with an inductive output filter. This converter allows the transfer of power without oversizing the inverter and a soft-switching mode of the transistors. The soft-switching mode and the sensitivity to the load variation, the coupling factor and the air gap (6-8 mm) are studied using the first harmonic method. The choice of the working range and the validity limit of the analysis method are presented. Theoretical results are validated experimentally with a 3 kW prototype.

Novel zero-current-switching PWM converters

Abstract: This paper presents a new family of pulsewidth-modulated (PWM) converters, featuring soft commutation of the semiconductors at zero current (ZC) in the transistors and zero voltage (ZV) in the rectifiers. Besides operating at constant frequency and with reduced commutation losses, these new converters have output characteristics similar to the hard-switching-PWM counterpart, which means that there is no circulating reactive energy that would cause large conduction losses. The new family of zero-current-switching (ZCS)-PWM converters is suitable for high-power applications using insulated gate bipolar transistors (IGBTs). The advantages of the new ZCS-PWM boost converter employing IGBTs, rated at 1.6 kW and operating at 20 kHz, are presented. This new ZCS operation can reduce the average total power dissipation in the semiconductors practically by half, when compared with the hard-switching method. This new ZCS-PWM boost converter is suitable for high-power applications using IGBTs in power-factor correction. The principle of operation, theoretical analysis, and experimental results of the new ZCS-PWM boost converter are provided in this paper to verify the performance of this new family of converters.

Feedforward control of DC-DC PWM boost converter

Abstract: A new feedforward control circuit suitable for applications in the dc-dc pulsewidth modulated (PWM) boost converter operated in the continuous conduction mode (CCM) is proposed. Its principle of operation is described, analyzed for steady state, and experimentally verified. The peak value of the sawtooth voltage at the noninverting input of a PWM modulator is held constant and the voltage at the inverting input of the PWM modulator varies in proportion to the converter dc input voltage. As a result, the complement of the on-duty cycle (1-D) is proportional to the dc converter input voltage, yielding the converter output voltage theoretically independent of the converter input voltage. The circuit is very simple and significantly improves line regulation of the output voltage. The measured open-loop line regulation at fixed loads was less than 5% for the converter dc input voltage change by 400%. The load regulation was also good even without a negative feedback loop.

Novel aspects of an application of 'zero'-ripple techniques to basic converter topologies

Abstract: Based on a short summary of the theoretical basics of the zero-ripple current phenomenon a special zero input current ripple boost converter topology as presented in the literature is investigated. It is shown that the complete suppression of the input current ripple of the system is only given in a theoretical extreme case. For a practical realization only such a ripple reduction of the input current of the basic converter structure is obtained as corresponds to a simple low-pass input filter. This is proven by a detailed analysis also for a zero-ripple Cuk and for a zero-ripple SEPIC converter structure. Furthermore, it is shown that the realization of a zero-ripple Cuk or zero-ripple SEPIC converter is not linked to a magnetic coupling of the input and output inductors, but can also be achieved by a simple rearrangement of the elements of the basic converter structures. There one can see that the operating behavior of a zero input current ripple SEPIC converter is equivalent to the operating behavior of a buck-boost converter stage with LC input filter. Finally, the advantages and disadvantages of the different realization approaches of zero-ripple topologies are compared. Also, an outlook towards the planned further treatment of the topic is given.

A new family of ZVS-PWM active-clamping DC-to-DC boost converters: analysis, design, and experimentation

Abstract: The purpose of this paper is to introduce a new family of zero-voltage switching (ZVS) pulse-width modulation (PWM) active-clamping DC-to-DC boost power converters. This technique presents ZVS commutation without additional voltage stress and a significant increase in the circulating reactive energy throughout the power converters. So, the efficiency and the power density become advantages when compared to the hard-switching boost power converter. Thus, these power converters may become very attractive in power factor correction applications. In this paper, the complete family of boost power converters is shown, and one particular circuit, taken as an example, is analyzed, simulated and experimented. 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%, and the power converter kept an efficiency up to 95% from 17% to 100% of full load, without additional voltage and current stresses.

Analysis of a ripple-free input-current boost converter with discontinuous conduction characteristics

Abstract: Coupled inductor techniques supply a method to reduce the power converter size and weight and achieve ripple-free current. The boost power converter is a very popular topology in industry. However, the input-current ripple hinders efforts to meet electromagnetic interference (EMI) requirements. In particular, the input current becomes discontinuous and pulsating when the conventional boost power converter operates in the discontinuous inductor-current mode. This paper describes a boost power converter which has the same discontinuous properties as the conventional boost power converter. However, the proposed boost topology has continuous or ripple-free input current when it operates with discontinuous inductor-current. The proposed topology is compared with traditional converter topologies, such as the Sepic and Cuk power converters. Simulation results are presented. The prototype is built to demonstrate the theoretical prediction. The proposed boost topology is simple, with straightforward control ~the same as pulse-width modulation (PWM)\.

A technique for reducing rectifier reverse-recovery-related losses in high-voltage, high-power boost converters

Abstract: A circuit technique that reduces the boost power converter losses caused by the reverse-recovery characteristics of the rectifier is described. The losses are reduced by inserting an inductor in the series path of the boost switch and the rectifier to control the di/dt rate of the rectifier during its turn-off. The energy from the inductor after the boost switch turn-off is returned to the input or delivered to the output via an active snubber. The same technique can be extended to any member of the PWM power converter family.

Feed-forward control of aircraft bus dc boost converter

Abstract: An open loop control arrangement for an electrical energy flow-controlling circuit coupling the varying terminal voltage of an energy storing capacitor to a fixed voltage direct current aircraft energy supply bus in order to supplement bus voltage transients. The open loop control arrangement allows energy flow from the varying terminal voltage of the capacitor to the fixed bus voltage by providing a time varying pulse modulation cycle in an energy conveying and voltage changing inductive element located in the energy coupling path. The open loop control arrangement senses input voltage rather than output voltage of the coupling circuit in what is termed a "feed forward " output regulation algorithm. A transistorized and integrated circuit inclusive preferred embodiment of the invention is disclosed in which a disconnect of the inductance from the aircraft supply bus is accomplished during shunt path inductance energy charging portions of an operating cycle.

Energy-efficient C-dump converters for switched reluctance motors

Abstract: Two energy-efficient converter topologies, derived from the conventional C-dump converter, are proposed for switched reluctance motor (SRM) drives. The proposed topologies overcome the limitations of the conventional C-dump converter, and could reduce the overall cost of the SRM drive. The voltage ratings of the dump capacitor and some of the switching devices in the proposed converters are reduced to the supply voltage (V/sub dc/) level compared to twice the supply voltage (2V/sub dc/) in the conventional C-dump converter. Also, the size of the dump inductor is considerably reduced. The converters have simple control requirements, and allow the motor phase current to freewheel during chopping mode. Simulation and experimental results of the converters are presented and discussed.

Anomalous bifurcations in DC-DC converters: borderline collisions in piecewise smooth maps

Abstract: Nonstandard bifurcations have been reported in power electronic DC-DC converters. We show that sampled data models with stroboscopic sampling yield piecewise smooth maps and that most of the observed "anomalous" bifurcations fall into a class called "border collision bifurcations". We offer analytical explanation of the dynamics of three converter topologies (current mode controlled first order buck converter, current mode controlled boost converter, duty cycle controlled buck converter).

Step-up/down DC-to-DC converter

Abstract: A converter for converting a DC voltage not stabilized, such as the terminal voltage of a battery, into a stable DC voltage, comprising a voltage comparison unit (2 in FIG. 1) and an operation changeover control unit (3). The voltage comparison unit (2) compares an input voltage and an output voltage. The operation changeover control unit (3) controls the changeover of the operations of the DC/DC converter (1) so that the DC/DC converter (1) may perform a step-down operation as the operation of a step-down type converter when the input voltage is higher than the output voltage as the result of the comparison, and that it may perform a step-up operation as the operation of a step-up type converter when the output voltage is higher than the input voltage. Thus, losses in the smoothing reactor and smoothing capacitor of the step-up/down converter are suppressed to enhance the efficiency thereof.

Half-bridge zero-voltage-switched PWM flyback DC/DC converter

Abstract: A DC-DC ZVS PWM converter circuit which utilizes the leakage inductance of an output transformer and a three-step operation cycle so as to reduce the voltage stress on the converter power switching transistors and to reduce the EMI noise emissions of the circuit.

High efficiency DC step-up voltage converter

Abstract: A DC power converter is disclosed for converting an input voltage to a final output voltage that is higher than the input voltage. The power converter includes an input terminal for receiving the input voltage and a final output terminal. A boost converter generates an intermediate voltage that is higher than the input voltage and lower than the final output voltage. The boost converter includes an inductor having a primary winding that has a first end connected to the input terminal, a switch for selectively connecting the second end of the first winding to ground, a first diode connected between the second end of the first winding and an intermediate node, and a first output capacitor connected between the intermediate node and ground. The boost converter produces at the first output capacitor an intermediate voltage higher than the input voltage. The step up converter described further includes a second winding on the inductor, a first end of which is connected to receive the intermediate voltage. A diode is connected between the second end of the second winding and the converter output terminal. A second output capacitor is connected between the converter output terminal and ground.

Development and testing of prototype models for a high-performance 300 MW self-commutated AC/DC converter

Abstract: A technical project is under way in Japan to develop a high-performance self-commutated power converter for future HVDC transmission and DC interconnection applications. In the first stage of the project, prototype power converter models for a 300 MW self-commutated converter were developed. The models were subjected to factory testing to verify the technology for series connection of a large number of gate turn-off thyristors (GTOs), a gate power supply from the high voltage main circuit and energy regeneration using snubber circuits. Satisfactory results were obtained.

Modeling, analysis, and application of buck converters in discontinuous-input-voltage mode operation

Abstract: By adding a suitable LC filter to the input of a buck power converter, it is possible to force the converter into discontinuous-input-voltage mode operation A buck power converter in this mode of operation has useful properties such as power factor correction and soft turn-off switching The operation, modeling, low-frequency behavior, and application of the power converter are studied Experimental results verifying the theoretical predictions are also presented

Single-switch AC/DC converter with power factor correction

Abstract: A single-switch, one-stage power factor correction converter with output electrical isolation is proposed. To relieve the voltage spike caused by the leakage inductance of the power transformer, two bulk storage capacitors are used. The proposed converter has both a good power factor correction and excellent line and load regulation capabilities with an efficiency of 87%.

Analysis and design of a fixed-frequency LCL-type series-resonant converter with capacitive output filter

Abstract: A fixed-frequency modified (LCL-type) series-resonant converter which uses a capacitive output filter is analysed using the Fourier series approach. Based on the analysis a simple design procedure is given. Detailed SPICE simulation results are presented for the designed converter to evaluate its performance for varying input supply voltage and for load variation. Experimental results obtained from a MOSFET based 500 W, 115 V output converter are presented to verify the analysis. The converter operates in lagging power factor mode for a very wide variation in the load and the supply voltage and is suitable for high voltage output applications.