Showing papers on "Buck converter published in 2010"
TL;DR: The main reasons why the conventional method for converter analysis fails are described and the different steps required to predict the power losses more accurately are documents.
Abstract: An accurate power loss model for a high-efficiency dual active bridge converter, which provides a bidirectional electrical interface between a 12-V battery and a high-voltage (HV) dc bus in a fuel cell car, is derived. The nominal power is 2 kW, the HV dc bus varies between 240 and 450 V, and the battery voltage range is between 11 and 16 V. Consequently, battery currents of up to 200 A occur at nominal power. In automotive applications, high converter efficiency and high power densities are required. Thus, it is necessary to accurately predict the dissipated power for each power component in order to identify and to properly design the heavily loaded parts of the converter. In combination with measured efficiency values, it is shown that conventional converter analysis predicts substantially inaccurate efficiencies for the given converter. This paper describes the main reasons why the conventional method fails and documents the different steps required to predict the power losses more accurately. With the presented converter prototype, an efficiency of more than 92% is achieved at an output power of 2 kW in a wide input/output voltage range.
388 citations
TL;DR: A novel high step-up dc-dc converter for fuel cell energy conversion that utilizes a multiwinding coupled inductor and a voltage doubler to achieve highstep-up voltage gain and high conversion efficiency.
Abstract: A novel high step-up dc-dc converter for fuel cell energy conversion is presented in this paper. The proposed converter utilizes a multiwinding coupled inductor and a voltage doubler to achieve high step-up voltage gain. The voltage on the active switch is clamped, and the energy stored in the leakage inductor is recycled. Therefore, the voltage stress on the active switch is reduced, and the conversion efficiency is improved. Finally, a 750-W laboratory prototype converter supplied by a proton exchange membrane fuel cell power source and an output voltage of 400 V is implemented. The experimental results verify the performances, including high voltage gain, high conversion efficiency, and the effective suppression of the voltage stress on power devices. The proposed high step-up converter can feasibly be used for low-input-voltage fuel cell power conversion applications.
343 citations
TL;DR: In this article, a T-S fuzzy observer is developed to reduce the number of measured signals and a fuzzy direct MPPT controller is proposed to achieve asymptotic MPPT control in which the observer and controller gains are obtained by separately solving two sets of linear matrix inequalities.
Abstract: This paper presents maximum power point tracking (MPPT) control for stand-alone solar power generation systems via the Takagi-Sugeno (T-S) fuzzy-model-based approach. In detail, we consider a dc/dc buck converter to regulate the output power of the photovoltaic panel array. First, the system is represented by the T-S fuzzy model. Next, in order to reduce the number of measured signals, a T-S fuzzy observer is developed for state feedback. Then, a fuzzy direct MPPT controller is proposed to achieve asymptotic MPPT control, in which the observer and controller gains are obtained by separately solving two sets of linear matrix inequalities. Different from the traditional MPPT approaches, the proposed T-S fuzzy controller directly drives the system to the maximum power point without searching the maximum power point and measuring insolation. Furthermore, when considering disturbance and uncertainty, robust MPPT is guaranteed by advanced gain design. Therefore, the proposed method provides an easier implementation form under strict stability analysis. Finally, the control performance is shown from the numerical simulation and experimental results.
263 citations
Patent•
03 Mar 2010TL;DR: In this paper, a power system coupled to a load includes a controller that receives a signal indicating a system operational state of the load and selects a power converter operational state as a function thereof.
Abstract: A power system having a power converter with an adaptive controller. The power system is coupled to a load and includes a power system controller that receives a signal indicating a system operational state of the load and selects a power converter operational state as a function thereof. The power system also includes a power converter with a power switch that conducts for a duty cycle to provide a regulated output characteristic at an output thereof. The power converter also includes a controller that receives a command from the power system controller to enter the power converter operational state and provides a signal to control the duty cycle of the power switch as a function of the output characteristic and in accordance with the command, thereby regulating an internal operating characteristic of the power converter to improve an operating efficiency thereof as a function of the system operational state.
224 citations
TL;DR: A novel high step-up converter is proposed for fuel-cell system applications to achieve a much higher voltage conversion ratio and avoid operating at extreme duty ratio and to adopt lower voltage rating devices to further reduce both switching and conduction losses.
Abstract: In this paper, a novel high step-up converter is proposed for fuel-cell system applications. As an illustration, a two-phase version configuration is given for demonstration. First, an interleaved structure is adapted for reducing input and output ripples. Then, a C?uk-type converter is integrated to the first phase to achieve a much higher voltage conversion ratio and avoid operating at extreme duty ratio. In addition, additional capacitors are added as voltage dividers for the two phases for reducing the voltage stress of active switches and diodes, which enables one to adopt lower voltage rating devices to further reduce both switching and conduction losses. Furthermore, the corresponding model is also derived, and analysis of the steady-state characteristic is made to show the merits of the proposed converter. Finally, a 200-W rating prototype system is also constructed to verify the effectiveness of the proposed converter. It is seen that an efficiency of 93.3% can be achieved when the output power is 150-W and the output voltage is 200-V with 0.56 duty ratio.
207 citations
TL;DR: In this article, an isolated bidirectional full-bridge dc-dc converter with high conversion ratio, high output power, and soft start-up capability is proposed, where the use of a capacitor, a diode, and a flyback converter can clamp the voltage spike caused by the current difference between the current-fed inductor and leakage inductance of the isolation transformer.
Abstract: An isolated bidirectional full-bridge dc-dc converter with high conversion ratio, high output power, and soft start-up capability is proposed in this paper. The use of a capacitor, a diode, and a flyback converter can clamp the voltage spike caused by the current difference between the current-fed inductor and leakage inductance of the isolation transformer, and can reduce the current flowing through the active switches at the current-fed side. Operational principle of the proposed converter is first described, and then, the design equation is derived. A 1.5-kW prototype with low-side voltage of 48 V and high-side voltage of 360 V has been implemented, from which experimental results have verified its feasibility.
198 citations
TL;DR: In this article, a sepic-integrated boost (SIB) converter was proposed to supplement the insufficient step-up ratio and distribute a voltage stress of a classical boost converter.
Abstract: For a nonisolated high step-up converter, the combination of a boost converter with a series output module is investigated in this paper. As a solution to supplement the insufficient step-up ratio and distribute a voltage stress of a classical boost converter, a sepic-integrated boost (SIB) converter, which provides an additional step-up gain with the help of an isolated sepic converter, is proposed. Since the boost converter and the sepic converter share a boost inductor and a switch, its structure is simple. Moreover, the SIB converter needs no current snubber for the diodes, since the transformer leakage inductor alleviates the reverse recovery. The operational principle and characteristics of SIB converter are presented, and verified experimentally with a 200 W, 42 V input, 400 V output prototype converter.
197 citations
TL;DR: In this article, the voltage regulation problem is addressed with a detailed analysis that starts with the modelling of the PV array and the converter, followed by study, design, simulation and practical experiments of three closed-loop control strategies for the buck converter.
Abstract: This study deals with the regulation of the output voltage of photovoltaic (PV) arrays. As a case study, the DC-DC buck converter is used as an interface between the PV array and the load, but other types of converters can be used for the same purpose. The input voltage of the converter is controlled in order to regulate the operating point of the array. Besides reducing losses and stress because of the bandwidth-limited regulation of the converter duty cycle, controlling the converter input voltage reduces the settling time and avoids oscillation and overshoot, making easier the functioning of maximum power point tracking (MPPT) methods. The voltage regulation problem is addressed with a detailed analysis that starts with the modelling of the PV array and the converter. This analysis is followed by study, design, simulation and practical experiments of three closed-loop control strategies for the buck converter. Control stability and implementation considerations are presented.
191 citations
TL;DR: Simulation and experimental results are shown to prove the ability of the indirect three-level sparse matrix converter to generate multilevel output voltages as well as to maintain a set of sinusoidal balanced input currents.
Abstract: A matrix converter is an ac-ac power converter topology that has received extensive research attention as an alternative to traditional ac-dc-ac converter. A matrix converter is able to convert energy from an ac source to an ac load without the need of a bulky and limited-lifetime energy-storage elements. The indirect three-level sparse matrix converter (I3SMC) is a new topology from this family that can synthesize three-level voltage in order to improve the output performance in terms of reduced harmonic content. This paper discusses the operating principles and a space-vector-modulation scheme for this topology. Simulation and experimental results are shown to prove the ability of this topology to generate multilevel output voltages as well as to maintain a set of sinusoidal balanced input currents. The performance of the converter is compared with the conventional matrix converter and an alternative multilevel matrix-converter topology in order to demonstrate the advantages and disadvantages of the I3SMC.
190 citations
TL;DR: In this article, a buck PFC front end with an output voltage in the 80-V range can maintain a high efficiency across the entire line and load ranges, compared to the boost PFC.
Abstract: In universal-line ac/dc converters that require power factor correction (PFC), maintaining a high efficiency across the entire line and load ranges poses a major challenge. Typically, a boost PFC front end exhibits 1%-3% lower efficiency at 100-V line compared to that at 230-V line. It is shown in this paper that a buck PFC front end with an output voltage in the 80-V range can maintain a high efficiency across the entire line and load ranges. A thorough analysis of the buck PFC converter operation and performance along with design optimization guidelines are presented. Experimental results obtained on a 90-W notebook adapter are provided. A loss analysis based on SIMPLIS and PSPICE simulations is also included. Major factors that contribute to the improved efficiency of the buck PFC versus the boost PFC are briefly explained.
162 citations
TL;DR: In this article, an interleaved-boost converter, magnetically coupled to a voltage-doubler circuit, is presented, which provides a voltage gain far higher than that of the conventional boost topology.
Abstract: This paper presents an interleaved-boost converter, magnetically coupled to a voltage-doubler circuit, which provides a voltage gain far higher than that of the conventional boost topology. Besides, this converter has low-voltage stress across the switches, natural-voltage balancing between output capacitors, low-input current ripple, and magnetic components operating with the double of switching frequency. These features make this converter suitable to applications where a large voltage step-up is demanded, such as grid-connected systems based on battery storage, renewable energies, and uninterruptible power system applications. Operation principle, main equations, theoretical waveforms, control strategy, dynamic modeling, and digital implementation are provided. Experimental results are also presented validating the proposed topology.
TL;DR: In this paper, a single-phase quasi-Z-source ac-ac converter was proposed, which can realize buck-boost, reversing, or maintaining the phase angle.
Abstract: This paper deals with a new family of single-phase ac-ac converters called single-phase quasi-Z-source ac-ac converters. The proposed converter inherits all the advantages of the traditional single-phase Z-source ac-ac converter, which can realize buck-boost, reversing, or maintaining the phase angle. In addition, the proposed converter has the unique features that the input voltage and output voltage share the same ground and the operation is in the continuous current mode. The operating principles of the proposed converter are described, and a circuit analysis is provided. In order to verify the performance of the proposed converter, a laboratory prototype was constructed with a voltage of 84 Vrms/60 Hz. The simulation and experimental results verified that the converter has a lower input current total harmonic distortion and higher input power factor in comparison with the conventional single-phase Z-source ac-ac converter.
14 Mar 2010
TL;DR: In this article, a 7.2 kV, 7.5 MVA converter model of the Modular Multilevel Converter (M2C) is presented and the cause of the circulating currents is investigated.
Abstract: The Modular Multilevel Converter (M2C) is an emerging multilevel converter for HVDC and FACTS as well as for future AC-fed traction vehicles or medium voltage drives (MVD). A suitable converter model of the Modular Multilevel Converter (M2C) is presented. A 7.2 kV, 7.5 MVA converter is taken as an example to analyze characteristic waveforms of the converter. The cause of the circulating currents — a phenomenon unique to this topology — is investigated. Furthermore, particular attention is paid to the current distribution in the converter cells for characteristic load phase angles.
TL;DR: In this paper, a soft-switched continuous-conduction-mode (CCM) boost converter is proposed for high-power applications such as power factor correction, hybrid electric vehicles, and fuel cell power conversion systems.
Abstract: This paper proposes a new soft-switched continuous-conduction-mode (CCM) boost converter suitable for high-power applications such as power factor correction, hybrid electric vehicles, and fuel cell power conversion systems. The proposed converter achieves zero-voltage-switched (ZVS) turn-on of active switches in CCM and zero-current-switched turn-off of diodes leading to negligible reverse-recovery loss. The components' voltage ratings and energy volumes of passive components of the proposed converter are greatly reduced compared to the conventional zero-voltage-transition converter. Voltage conversion ratio is almost doubled compared to the conventional boost converter. Extension of the proposed concept to realize multiphase dc-dc converters is discussed. Experimental results from a 1.5-kW prototype are provided to validate the proposed concept.
TL;DR: In this paper, a DC-DC converter with high step-up voltage gain is presented, which uses the coupled inductor and the voltage-lift technique to achieve high step up voltage gain.
Abstract: A DC-DC converter with high step-up voltage gain is presented. The proposed converter uses the coupled inductor and the voltage-lift technique to achieve high step-up voltage gain. Additionally, the voltage on the active switch is clamped, and the energy stored in the leakage inductor is recycled in the proposed converter. Therefore the voltage stress on the active switch is reduced, and the conversion efficiency is improved. Finally, a laboratory prototype circuit with input voltage 12-V, output voltage 100-V and output power 35-W is implemented to demonstrate the performance of the proposed converter.
TL;DR: The proposed ZVZCS PWM combined three-level dc/dc converter has the following advantages: all power switches suffer only half of the input voltage; the voltage across the output filter is very close to the output voltage, which can reduce the outputfilter inductance significantly; and the voltage stress of the rectifier diodes is reduced too, so that the converter is very suitable for high input voltage and wide input voltage range applications.
Abstract: This paper proposes a zero-voltage and zero-current-switching (ZVZCS) PWM combined three-level (TL) dc/dc converter, which is a combination of a ZVZCS PWM TL converter with a ZVZCS PWM full-bridge converter. The proposed converter has the following advantages: all power switches suffer only half of the input voltage; the voltage across the output filter is very close to the output voltage, which can reduce the output filter inductance significantly; and the voltage stress of the rectifier diodes is reduced too, so that the converter is very suitable for high input voltage and wide input voltage range applications. The converter also can achieve zero-voltage-switching for the leading switches and ZCS for the lagging switches in a wide load range to achieve higher efficiency. The design considerations and procedures are presented in this paper. The operation principle and characteristics of the proposed converter are analyzed and verified on a 400-800-V input and 54-V/20-A output prototype.
TL;DR: A zero-voltage- and zero-current-switching full-bridge (FB) converter with secondary resonance with high efficiency, minimum number of devices, and low cost is presented and analyzed.
Abstract: A zero-voltage- and zero-current-switching full-bridge (FB) converter with secondary resonance is presented and analyzed. The primary side of the converter is composed of FB insulated-gate bipolar transistors, which are driven by phase-shift control. The secondary side is composed of a resonant tank and a half-wave rectifier. Without an auxiliary circuit, zero-voltage switching (for leading-leg switches) and zero-current switching (for lagging-leg switches) are achieved in the entire operating range. To implement the converter without an additional inductor, the leakage inductance of the transformer is utilized as the resonant inductor. Due to its many advantages, including high efficiency, minimum number of devices, and low cost, this converter is attractive for high-voltage and high-power applications. The analysis and design considerations of the converter are presented. A prototype was implemented for an application requiring a 5-kW output power, an input-voltage range varying from 250 to 350 V, and a 350-V output voltage. The experimental results obtained from a prototype verify the analysis. The prototype's efficiency at full load is over 95.5%.
TL;DR: In this paper, a boundary control for dc-dc buck converters subject to instantaneous constant-power loads is examined and sufficient conditions for large-signal stability of the closed-loop system are established.
Abstract: This paper examines a boundary control for dc-dc buck converters subject to instantaneous constant-power loads. These loads introduce a destabilizing nonlinear effect on the converter through an inverse voltage term that leads to significant oscillations in the main bus voltage or its collapse. Converter dynamics are analyzed in both switching states and the various operating regions of switch interaction with a first-order switching surface (boundary) are identified. Furthermore, sufficient conditions for large-signal stability of the closed-loop system are established. The analysis indicates that a linear switching surface with a negative slope passing through the desired operation point yields a stable operation. It is also shown that instability as well as system-stalling, which we term the invariant-set problem, may still occur in reflective mode. However, a hysteresis band that contains the designed boundary may be used to prevent system-stalling. This hysteresis band also allows for a practical implementation of the controller by avoiding chattering. Design considerations are included and recommendations are given. The theoretical analysis is verified by simulations and experimental results.
TL;DR: This paper proposes a multilevel digitally controlled power supply suitable for wireless communication transmitters and shows that the proposed system is able to produce a 15% overall increase in efficiency in a complete envelope tracking system.
Abstract: Wireless communication transmitters have very low efficiencies due to the use of linear radiofrequency power amplifiers Several techniques have been proposed over the years to improve the efficiency of these systems One of the most promising is called the envelope tracking technique, which is based on using a fast switching mode power supply to provide a varying voltage to the power amplifier that tracks the envelope of the transmitted signal The amplifier can, thus, operate continuously near its theoretical maximum efficiency, greatly improving the overall efficiency of the communication system This paper proposes a multilevel digitally controlled power supply suitable for this application It is shown to perform very well, achieving very high efficiency, high-output power capability and tracking bandwidths above 50 kHz This paper also shows that the proposed system is able to produce a 15% overall increase in efficiency in a complete envelope tracking system
TL;DR: In this paper, a method of maintaining high power-conversion efficiency across the entire load range and its circuit implementations are described, which substantially increases the conversion efficiency at light loads by minimizing switching and driving losses of semiconductor switches, as well as core losses of magnetic components.
Abstract: In this paper, a method of maintaining high power-conversion efficiency across the entire load range and its circuit implementations are described. The proposed method substantially increases the conversion efficiency at light loads by minimizing switching and driving losses of semiconductor switches, as well as core losses of magnetic components. These losses are minimized by periodically turning off and on the power converter, and by controlling the converter so that when the converter is on, it operates at the power level that exhibits the maximum efficiency. The performance of the proposed method was evaluated on a 500-W, 400-V/12-V dc-dc converter and a 1-kW ac-dc boost power-factor-correction front-end.
TL;DR: In this article, a two-stage power converter consisting of a boost converter in parallel with a buck-boost converter is proposed to directly convert the low AC input voltage to the required high dc output voltage at a higher efficiency.
Abstract: The conventional two-stage power converters with bridge rectifiers are inefficient and may not be practical for the low-voltage microgenerators. This paper presents an efficient ac-to-dc power converter that avoids the bridge rectification and directly converts the low AC input voltage to the required high dc output voltage at a higher efficiency. The proposed converter consists of a boost converter in parallel with a buck-boost converter, which are operated in the positive half cycle and negative half cycle, respectively. Detailed analysis of the converter is carried out to obtain relations between the power, circuit parameters, and duty cycle of the converter. Based on the analysis, control schemes are proposed to operate the converter. Design guidelines are presented for selecting the converter component and control parameters. A self-starting circuit is proposed for independent operation of the converter. Detailed loss calculation of the converter is carried out. Simulation and experimental results are presented to validate the proposed converter topology and control schemes.
TL;DR: The design, realization, and performance evaluation of a single-phase 3-kW dc/ac power converter, using an active-bridge dc/dc converter and a full-bridge DC/ac, are introduced, presenting a novel solution on the industrial scenario for the considered application.
Abstract: In this paper, the design, realization, and performance evaluation of a single-phase 3-kW dc/ac power converter, using an active-bridge dc/dc converter and a full-bridge dc/ac, are introduced, presenting a novel solution on the industrial scenario for the considered application. Control algorithms, including the maximum power point tracking, paralleling to the grid, and converter switching signals, are digitally implemented on a standard microcontroller.
TL;DR: In this article, a buck-boost converter with high efficiency and small output ripple is proposed to extend the battery life of portable devices, and the hybrid buck-Boost feedforward (HBBFF) technique is integrated in this converter to achieve fast line response.
Abstract: This paper presents a buck-boost converter with high efficiency and small output ripple to extend the battery life of portable devices. Besides, the hybrid buck-boost feedforward (HBBFF) technique is integrated in this converter to achieve fast line response. The new control topology minimizes the switching and conduction losses at the same time even when four switches are used. Therefore, over a wide input voltage range, the proposed buck-boost converter with minimum switching loss like the buck or boost converter can reduce the conduction loss through the use of the reduced average inductor current (RAIC) technique. Moreover, the HBBFF technique minimizes the voltage variation at the output of error amplifier. Consequently, a fast line transient response can be achieved with small dropout voltage at the output. Especially, the converter can offer good line and load regulations to ensure a regulated output voltage without being affected by the decreasing battery voltage. Experimental results show that the output voltage is regulated over a wide battery lifetime, and the output ripple is minimized during mode transition. The peak efficiency is 97% and the transient dropout voltage can be improved substantially.
TL;DR: An improved soft-switching full-bridge phase-shifted pulsewidth modulation converter using insulated-gate bipolar transistors with a special auxiliary transformer with new significant feature in suppression of circulating current also in short-circuit conditions is presented.
Abstract: An improved soft-switching full-bridge phase-shifted pulsewidth modulation converter using insulated-gate bipolar transistors with a special auxiliary transformer is presented in this paper. Zero-voltage switching for leading leg and zero-current switching for lagging leg switches in the converter are achieved for full-load range from no load to short circuit by adding an active energy recovery clamp and auxiliary circuits. The new significant feature of the converter consists in suppression of circulating current also in short-circuit conditions. The proposed converter is very attractive for applications where short circuit and no load are the normal states of the converter operation, e.g., arc welding. The principle of operation is explained and analyzed, and experimental results are presented on a 3-kW 50-kHz laboratory converter model.
TL;DR: A novel soft-switching approach for rechargeable batteries by inserting an auxiliary switch in series with a resonant capacitor can obtain a novel ZCS buck dc-dc battery charger and significantly decrease the switching losses in active power switches.
Abstract: To obtain zero-current-switching (ZCS) operation, this paper develops a novel soft-switching approach for rechargeable batteries. By inserting an auxiliary switch in series with a resonant capacitor, the proposed topology can obtain a novel ZCS buck dc-dc battery charger and significantly decrease the switching losses in active power switches. The proposed ZCS dc-dc battery charger has a straightforward structure, low cost, easy control, and high efficiency. The operating principles and design procedure of the proposed charger are thoroughly analyzed. The optimal values of the resonant components are computed by applying the characteristic curve and electric functions derived from the circuit configuration. Finally, a prototype charger circuit designed for a 12-V 48-Ah lead acid battery is constructed and tested to confirm the theoretical predictions. The maximum charging efficiency of the proposed topology during the overall charging period is 90.3%. Satisfactory performance is obtained from the experimental results.
TL;DR: The novel control strategy enables simpler dynamics compared to a standard buck converter with an input filter, good regulation capability, low electromagnetic interference, lower source current ripple, ease of control, and continuous input current waveform in both modes of operation.
Abstract: This paper presents the analysis and novel controller design for a hybrid switched-capacitor bidirectional dc/dc converter. Features of voltage step-down, step-up, and bidirectional power flow are integrated into a single circuit. The novel control strategy enables simpler dynamics compared to a standard buck converter with an input filter, good regulation capability, low electromagnetic interference, lower source current ripple, ease of control, and continuous input current waveform in both modes of operation (buck and boost modes).
TL;DR: In this article, a general expression for winding loss (copper loss) including harmonics for an inductor carrying periodic non-sinusoidal current is presented, where the skin and proximity effects are taken into account.
Abstract: A general expression for winding loss (copper loss) including harmonics for an inductor carrying periodic non-sinusoidal current is presented. The skin and proximity effects are taken into account. Expressions for amplitudes of inductor current harmonics are derived and illustrated as functions of duty cycle for selected non-isolated converters namely buck, boost and buck-boost converters. An example of inductor design procedure using the area-product method is shown for a buck converter operating in continuous conduction mode (CCM). The amplitude spectra of the inductor current, winding resistance and winding power loss are illustrated. Inductor winding losses in the designed inductor are analysed using MatLab simulations. Experimental results using the designed inductor are also presented.
TL;DR: In this paper, a new soft-switching boost converter is proposed, which utilizes a soft switching method using an auxiliary circuit with a resonant inductor and capacitor, auxiliary switch, and diodes.
Abstract: A new soft-switching boost converter is proposed in this paper. The conventional boost converter generates switching losses at turn on and off, and this causes a reduction in the whole system's efficiency. The proposed boost converter utilizes a soft-switching method using an auxiliary circuit with a resonant inductor and capacitor, auxiliary switch, and diodes. Therefore, the proposed soft-switching boost converter reduces switching losses more than the conventional hard-switching converter. The efficiency, which is about 91% in hard switching, increases to about 96% in the proposed soft-switching converter. In this paper, the performance of the proposed soft-switching boost converter is verified through the theoretical analysis, simulation, and experimental results.
TL;DR: In this paper, a pseudo-type III (PT3) compensator was proposed to maintain the fast load transient response of the conventional Type III compensator by adding a high-gain low-frequency path (via error amplifier) with a moderate-gain high-frequencypath (via bandpass filter) at the inputs of PWM comparator.
Abstract: Monolithic PWM voltage-mode buck converters with a novel Pseudo-Type III (PT3) compensation are presented. The proposed compensation maintains the fast load transient response of the conventional Type III compensator; while the Type III compensator response is synthesized by adding a high-gain low-frequency path (via error amplifier) with a moderate-gain high-frequency path (via bandpass filter) at the inputs of PWM comparator. As such, smaller passive components and low-power active circuits can be used to generate two zeros required in a Type III compensator. Constant Gm/C biasing technique can also be adopted by PT3 to reduce the process variation of passive components, which is not possible in a conventional Type III design. Two prototype chips are fabricated in a 0.35-μm CMOS process with constant Gm/C biasing technique being applied to one of the designs. Measurement result shows that converter output is settled within 7 μs for a load current step of 500 mA. Peak efficiency of 97% is obtained at 360 mW output power, and high efficiency of 86% is measured for output power as low as 60 mW. The area and power consumption of proposed compensator is reduced by > 75 % in both designs, compared to an equivalent conventional Type III compensator.
01 Nov 2010
TL;DR: In this article, the authors presented a DC-AC converter that merges a DCDC converter and an inverter in a single-stage topology to be used as an interface converter between photovoltaic systems and the electrical AC grid.
Abstract: This paper presents a DC-AC converter that merges a DC-DC converter and an inverter in a single-stage topology to be used as an interface converter between photovoltaic systems and the electrical AC grid. This topology is based on a full bridge converter with three levels output voltage, where two diodes and one inductor have been added in order to create a Boost converter. The control system of the proposed converter is based on two hysteretic controllers: one for the grid injected current and the other for controlling the panel current. A prototype of the proposed converter including power and control circuits was developed. The MPPT algorithm is not yet implemented and, therefore, to obtain experimental results an additional power supply is used to emulate the PV panel. Theoretical analysis and design criteria are presented together with simulated results to validate the proposed concepts. Experimental results are obtained in a lab prototype to evidence the feasibility and performance of the converter.