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The extra-LC auxiliary-resonant-snubber-based converter (ELCARSC), as a soft-switching converter, has the advantages of low switching loss, low electromagnetic interference noise, and low-output distortion caused by the dead-time effect. However, the dead-time effect is still the main problem in a high-precision application. Besides, the traditional control and compensation methods rely on the accuracy of the circuit parameters, especially the junction capacitance, thus resulting in compensation error. Therefore, this paper proposed a novel high-precision control method through modulating the initial resonant current to eliminate the dead-time effect of ELCARSC. The method does not need complicated online calculation and reduces the dependence on the accuracy of the circuit parameters, especially the influence of the junction capacitances of the switches. In this paper, the dead-time effect of the ELCARSC is analyzed. The output voltage error with the conventional variable-timing control method is analyzed. Subsequently, the proposed modulated initial resonant current control is introduced. Finally, a prototype was developed that verified the effectiveness of the control method. The quality of the output current and voltage is improved by utilizing the proposed control method. However, the peak current of the auxiliary switch is increased. [ABSTRACT FROM AUTHOR]

In applications that demand single-input dual-output (SIDO) or dual-input single-output (DISO) dc–dc converters, employing two separate single-input single-output (SISO) converters is a solution. However, the number of components is doubled, resulting in high overall cost. In order to reduce costs, this paper proposes a novel topology synthesis methodology, with which a variety of SIDO and DISO dc–dc converters with reduced components can be derived. The principle of topology synthesis states that integrated SIDO and DISO dc–dc converters can be easily developed from conventional SISO converters by replacing a diode with a basic cell inclusive of additional input/output port. The principle is effective for many SISO dc–dc converters, and as an example, topology synthesis based on buck, boost, buck–boost, Cuk, sepic, and zeta SISO converters is performed in this paper. In order to achieve better understanding of the proposed converters, the integrated SIDO Cuk converter is specifically analyzed and experimentally verified. In comparison with the conventional scheme of two separate SISO Cuk converters, good cross regulation is retained while the number of diodes, inductors, and capacitors is reduced in the proposed SIDO Cuk converter. In addition, zero-voltage-switching operation of one switch is achieved, contributing to lower switching losses. Finally, a prototype circuit with 48-V input and 156 V/1 A, 24 V/4 A outputs is built to validate the theoretical analysis. [ABSTRACT FROM PUBLISHER]

This paper presents three unidirectional step-up ac–dc converter topologies with voltage multiplication on their outputs. The first topology is the hybrid boost rectifier and the other two are novel bridgeless structures, all based on the integration of boost rectifier and the ladder switched-capacitor (SC) cell. The new hybrid structures provide high voltage gain with low voltage stress across the switches, high-power factor, and output voltage regulation. This paper presents the principle of operation, steady-state and dynamic analysis, design methodology, and experimental verification. A different approach is also presented for the design methodology of the SC cell and for the analysis of its influence on the dynamic model. Three 1000-W prototypes with a 220-V input voltage, 800-V output voltage, and 100-kHz switching frequency were designed to corroborate the theoretical study. The best efficiency was 97.1$\%$ in the proposed bridgeless versions and the voltage stress across the switches stands around 400 V. Furthermore, a comparison between the proposed structures and previous topologies is also presented. [ABSTRACT FROM PUBLISHER]

In this paper, a voltage sensorless controller is developed for a two-switch single-phase rectifier that involves power factor correction and active pulsating power buffering without electrolytic capacitors. While a two-switch rectifier normally requires four sensed signals for control, only one current sensor is required in this proposal, thereby offering advantages such as low cost, high compactness, isolation between control and power circuits, and improved reliability. While the basic operating principle follows that of a conventional voltage sensorless controller for single-switch converters, several critical design considerations are the key to the success of the implementation which is explained in detail. The feasibilities of the controller are experimentally testified with a 100-W rectifier prototype regarding both steady state and dynamic performance. [ABSTRACT FROM AUTHOR]

For photovoltaic applications, the flyback microinverter with pseudo-dc-link is popular as a simple topology but brings large transformer turns ratio and thus large leakage inductance, which would deteriorate the converter efficiency. To solve this issue, based on the nonisolated pseudo-dc-link structure, this paper proposed a hybrid boost–flyback/flyback (BF/F) microinverter. This new topology is operated at the BF mode for the most segment of a half grid cycle and the F mode for the rest. During the BF mode, high voltage gain with low voltage stress is easily available in minimized transformer turns ratio. Besides, the leakage energy is recycled and the turn-off voltage spike of the main switch is clamped, as a result of a passive snubber inherently contained in this mode. Given that the BF mode is lack of step-down function, the F mode is developed to regulate the output voltage even for values lower than the input voltage. The operation and characteristic of the hybrid BF/F microinverter in boundary conduction mode are analyzed in detail, and the mathematical expression of reference current is derived theoretically to guarantee high power quality. Finally, a 240 W prototype was implemented to validate the theoretical analysis and the benefits of the proposed topology. [ABSTRACT FROM AUTHOR]

Control-to-output transfer function of the classical boost converter in continuous conduction mode contains a right-half-plane (RHP) zero that limits its frequency response. In this paper, to eliminate this zero and enhance the dynamic performance, a forward path for energy transfer to output within the on interval of the power switch is provided using the magnetic coupling. This approach simply eliminates the RHP zero by introducing an inductor coupled to the boost inductor, a diode, and a capacitor into the classical boost topology. In addition, the provided forward path enhances the voltage gain, which makes it possible to achieve a smaller operating duty cycle and reduced voltage stress for the power switch in applications with large voltage conversion ratios. Using this approach does not complicate the control structure, and a traditional single-loop voltage control scheme can be used to regulate the output voltage. The proposed approach is analytically examined by obtaining the averaged state-space model of the resulting converter, and a criterion to eliminate the RHP zero is presented. Experimental results from an implemented laboratory prototype for 48- to 200-V voltage conversion and 100-W nominal power are provided. [ABSTRACT FROM AUTHOR]

The interleaved bidirectional buck–boost converter dual active half-bridge (IBBC-DAHB) dc–dc converter consists of two converters IBBC and DAHB and a coupled inductor. The IBBC-DAHB converter has significant features such as low ripple current at the low-voltage side, low current stress on the input inductors, voltage stress across the switches less than the high-voltage side, high voltage gain, and zero-voltage soft switching. The converter offers high efficiency using phase-shift modulation when it operates at a nominal design operating point. However, the efficiency decreases due to high circulating current, high current stress, and limited soft-switching range when the source and load voltages deviate from their nominal values. This paper employs both duty cycle and phase-shift modulation methods to improve the above mentioned shortcomings using voltage matching for the DAHB converter. The proposed converter is analyzed and a 500-W experimental prototype with 40–60 V input voltage and 400 V output voltage under 100 kHz switching frequency is implemented to verify the theoretical results. The maximum efficiency of 97.15% is achieved at 60 V and 400 W. A flat efficiency characteristic for the converter is derived by the proposed control method, where the efficiency at 20% of nominal load is 91% and much higher than the phase-shift control, which is 70.8%. [ABSTRACT FROM AUTHOR]

In this paper, an input-series flyback converter with the coupled-inductor-based passive snubber is proposed, where the input-series converter is based on transformer integration, and the passive snubber is composed of inductors, capacitors, and diodes. The inductors of the snubber in various series modules are made on a common magnetic core, and the coupled-inductor scheme is adopted. With the help of the coupled inductor, active input voltage sharing of the input-series converter can also be achieved after the switches are turned off, and voltage sharing of the switch in each series module can be ensured, which overcome the shortcomings of the existing input-series flyback converter. Active voltage sharing processes caused by the coupled inductor are analyzed in detail. Furthermore, the design guideline of the passive snubber is discussed. Finally, the experimental study has been done on a 1500 Vdc/60 W laboratory-made prototype composed of three flyback series modules, and the feasibility of the proposed method and the theoretical analysis is verified by the experimental results. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive and generalized analysis of the bidirectional dual active bridge (DAB) dc–dc converter using triple phase shift (TPS) control to enable closed-loop power regulation while minimizing current stress. The key new achievements are a generic analysis in terms of possible conversion ratios/converter voltage gains (i.e., Buck/Boost/Unity), per unit based equations regardless of DAB ratings, and a new simple closed-loop controller implementable in real time to meet desired power transfer regulation at minimum current stress. Per unit based analytical expressions are derived for converter ac rms current as well as power transferred. An offline particle swarm optimization (PSO) method is used to obtain an extensive set of TPS ratios for minimizing the rms current in the entire bidirectional power range of –1 to 1 per unit. The extensive set of results achieved from PSO presents a generic data pool, which is carefully analyzed to derive simple useful relations. Such relations enable a generic closed-loop controller design that can be implemented in real time avoiding the extensive computational capacity that iterative optimization techniques require. A detailed Simulink DAB switching model is used to validate the precision of the proposed closed-loop controller under various operating conditions. An experimental prototype also substantiates the results achieved. [ABSTRACT FROM AUTHOR]

MR16 lighting system with a high-frequency step-down electronic transformer is widely used in commercial lighting. In this paper, a single-switch quadratic boost light emitting diode (LED) driver compatible with electronic transformers for the MR16 lighting system is proposed and analyzed. It combines a prestage boost power factor correction (PFC) converter and a second-stage boost dc–dc converter with a single switch. The effect of the dc link voltage ripple of the prestage boost PFC converter on the output of the second-stage boost dc–dc converter is eliminated by a fast voltage mode control loop of a second-stage circuit. Therefore, flicker-free low ripple LED current is achieved. With a small dc link voltage ripple of prestage, the turn-on time of the active switch is almost constant in a half-line cycle. Therefore, PFC can be achieved with inductor current of prestage operating in a discontinuous conduction mode. With small input capacitance, the proposed LED driver presents a good compatibility performance with different kinds of electronic transformers. Furthermore, the proposed LED driver needs only one active switch and one control loop, which makes circuit volume small and low cost. Finally, a 4 W LED driver for a small-size MR16 lighting system is provided to verify the studied results. [ABSTRACT FROM AUTHOR]

Switched-capacitor converter (SCC) featuring high efficiency and power density has attracted industry interest, but weak output voltage regulation hinders its application. This paper presents an optimized phase-shift (PS) control strategy for a bridge modular SCC, utilized in energy storage system, to obtain continuous conversion ratio and high-efficiency operation. By employing a small inductor as current buffer, the control strategy could be implemented to regulate output voltage conveniently with excellent steady and dynamic performance in step-down mode as well as step-up mode. Most importantly, the high-efficiency operation mechanism never reported before is revealed here. Correspondingly, the active circumfluence could be controlled through optimizing the range of PS time, which will avoid the loss in circuit self. Meanwhile, the soft-switching conditions of all the switches are comprehensively analyzed and soft-switching operations are achieved according to the logic timing control of the power devices, improving efficiency further. Finally, the prototype of the proposed converter was built and the experimental results validated the principle and features of the conversion method. [ABSTRACT FROM AUTHOR]

In this paper, a novel buck–boost converter with low electric stress on components and negative output voltage is proposed. The operational principle, steady-state analysis, and small-signal modeling of the proposed buck–boost converter in continuous conduction mode are presented. Comparisons among another five buck–boost converters and the proposed buck–boost converter are presented. It is found that the proposed converter's voltage gain is smaller than the other converters’ in step-down mode. Also, based upon the comparisons among the same kind and same number of components, the voltage and current stresses on the power switch of the proposed buck–boost converter are less than or equal to those of the comparative converters, and the voltage stress on the charge pump capacitor and the switching device power rating of the proposed buck–boost converter are always lower than those of other comparative converters. The efficiency of the proposed buck–boost converter is highest among those converters having the same number of elements. These advantages make component selection for the proposed converter much easier, and it can be used directly in applications needing a negative voltage source. Finally, simulation results and circuit experiments are given for validating the effectiveness of the proposed buck–boost converter. [ABSTRACT FROM AUTHOR]

Three-phase bridge converter is popular in ac–dc power conversion. The conventional sensor control with inner current loop and outer voltage loop is often used to control the three-phase bridge converter. Many three-phase sensorless control methods had been proposed to control the bridge converter with considering the inductance and inductor resistance. In this paper, the voltage drop of the power semiconductor is first considered in the proposed three-phase current sensorless control method. At first, the dynamic behaviors of three-phase bridge converter for power factor correction (PFC) applications are studied, and its equivalent three-switch model is developed. Based on this developed model, three-phase current sensorless control with only voltage controller is proposed. Additionally, the voltage-loop transfer function of PFC bridge converter controlled by the proposed method is modeled, and the result is helpful to obtain the controller parameter. The proposed control method is implemented on the DSP-based platform for evaluation. Finally, the provided simulation and experimental results demonstrate the performance of the proposed method. [ABSTRACT FROM AUTHOR]

This paper proposes a novel nonisolated single-input dual-output three-level dc–dc converter (SIDO-TLC) appropriate for medium- and high-voltage applications. The SIDO-TLC is an integration of the three-level buck and boost converters, whose output voltages are regulated simultaneously. Reducing voltage stress across semiconductor devices, improving efficiency, and reducing inductors size are among the main merits of the new topology. Moreover, due to the considerably reduced volume of the step-down filter capacitor, a small film capacitor can be used instead, whose advantages are lower equivalent series resistance and a longer lifespan. A closed-loop control system has been designed based on a small-signal model derivation in order to regulate the output voltages along with the capacitors’ voltage balancing. In order to verify the theoretical and simulation results, a 300-W prototype was built and experimented. The results prove the aforementioned advantages of the SIDO-TLC, and the high effectiveness of the balancing control strategy. Furthermore, the converter shows very good stability, even under simultaneous step changes of the loads and input voltage. [ABSTRACT FROM AUTHOR]

In this paper, a three-level quasi-switched boost T-type inverter (3L qSBT2I) is proposed. A new pulse-width modulated (PWM) control method is presented to reduce the inductor current ripple of the qSBT2 I. In the introduced PWM technique, the shoot-through duty cycle is maintained constant to keep the modulation index as high as possible. Then, the only control parameters of the qSBT2I are the duty cycles of the two additional switches. By controlling the duty cycles of the two additional switches, the voltage gain of the proposed qSBT2 I can be improved to a value larger than that of the conventional 3L impedance source inverters. The steady-state analysis, operating principles, and comparisons with the impedance source-based 3L inverters are presented. A 1-kW prototype is constructed to verify the operating principle of the 3L qSBT2I. An indirect dc-link voltage regulator and a capacitor voltage-balance controller are applied to the proposed qSBT2I. Simulation and experimental results are presented. [ABSTRACT FROM AUTHOR]

Single-stage power-factor-corrected (S2PFC) power supplies usually suffer from high voltage stress, due to lack of control on the intermediate bus capacitor voltage. In the past, analysis of such voltage stress was mostly based on steady-state condition without providing sufficient explanation during the transient circuit operation. This paper revisits the problem at circuit level and reports that the root cause is due to the inherent negative current feedback property of the output inductor or the transformer operating in continuous conduction mode (CCM). Based on the finding, this paper further proposes a new approach to reducing the voltage stress by adding an auxiliary circuit branch to existing S2PFC converters. The additional circuit branch limits the effect of negative current feedback by suppressing the change of output current slope due to change of load. This assists the pulsewidth modulation controller to track the change of load better such that the bus capacitor voltage range is reduced through duty cycle control. The auxiliary circuit branch also reduces reverse-recovery-related losses of the converter under CCM operation. A laboratory prototype using the popular boost PFC converter combined flyback dc/dc converter was built and tested to confirm the analysis and effectiveness of the approach. [ABSTRACT FROM AUTHOR]

Connecting legs in parallel in a voltage source inverter is a way to increase the output current and, thus, its rated power. The connection can be made using either coupled or uncoupled inductors, and achieving an even contribution to the output current from all the legs is a crucial issue. Circulating currents produce additional losses and stress to the power devices of the converter. Therefore, they should be controlled and minimized. An efficient technique to attain such balance when coupled inductors are used is presented in this paper. The proposed technique can also be used when the inductors are uncoupled, since it is a particular case where the coupling coefficients are zero. This technique does not include proportional–integral controllers and does not require any parameter tuning either. The exact control action needed to reach current balance is straightforwardly calculated and applied. Experimental results are shown in this paper to verify the efficiency of the proposed balancing method. [ABSTRACT FROM PUBLISHER]

Conventional zero-voltage and zero-current-switching (ZVZCS) full-bridge converters are widely used because they can realize zero-voltage switching (ZVS) for the leading leg and zero-current switching (ZCS) for the lagging leg. However, the large turn-off loss of the leading leg is still unacceptable in high-voltage high-power applications where insulated-gate bipolar transistors (IGBTs) with current tailing are employed. Hence, it is preferable to achieve ZCS for all IGBTs of full-bridge converters. This paper analyzes the ZCS conditions for pulsewidth modulated (PWM) full-bridge converters and proposes a general strategy for achieving ZCS for main switches, including the control strategy and design method of the topology. Based on this theory, a novel ZCS PWM full-bridge converter with simple auxiliary circuit is derived and tested. It can achieve ZCS not only for the main switches of full-bridge converter, but for the auxiliary switch as well, and obtain high efficiency. The operation principle of the proposed ZCS PWM full-bridge converter and the design procedure are presented. The experimental results of a 600 V/2.5 kW prototype are also included to verify the theoretical analysis. [ABSTRACT FROM PUBLISHER]

Due to the relatively low output voltage of photovoltaic (PV) source, a high step-up converter with high efficiency is needed when the PV source is connected to the power grid. A novel high step-up converter based on two switched capacitors and a coupled inductor is proposed in this paper. The operating principle is analyzed and the voltage gain is derived. A 100-W prototype is fabricated in the laboratory to verify the theoretical analysis, and the highest efficiency is 96.4%. [ABSTRACT FROM PUBLISHER]

This paper proposes the combination of a novel modified quasi-Z-source (MqZS) inverter with a single-phase symmetrical hybrid three-level inverter in order to boost the inverter three-level output voltage. The proposed single-phase MqZS hybrid three-level inverter provides a higher boost ability and reduces the number of inductors in the source impedance, compared with both the single-phase three-level neural-point clamped quasi-Z-source inverter and the single-phase quasi-Z-source cascaded multilevel inverter. Additionally, it can be extended to obtain the nine-level output voltage by cascading two three-level pulse width modulation switching cells with a separate MqZS and a dc source, which herein is called a single-phase MqZS cascaded hybrid five-level inverter (MqZS-CHI). A modified modulation technique based on an alternative phase opposition disposition scheme is suggested to effectively control the shoot-through state for boosting the dc-link voltage and balancing the two series capacitor voltages of the MqZS. The performances of both the proposed MqZS-CHI and the modulation techniques are verified through simulation and experimental results. [ABSTRACT FROM PUBLISHER]

This paper extends the trans-Z-source concept to ac–ac power conversion and proposes a novel single-phase trans-Z-source ac–ac converter. The proposed converter retains the advantages of its existing Z-source/quasi-Z-source counterparts in which the output voltage can be boosted and in-phase with the input voltage or bucked/boosted and out-of-phase with the input voltage. Meanwhile, a coupled inductor is introduced into the proposed converter, and the turns ratio of the coupled inductor become another control variable beside the duty cycle to obtain extreme voltage gain. Importantly, the input voltage and output voltage share the same ground, and the input current could be continuous, which is a benefit for reducing input current harmonics. Most important of all, the safe-commutation strategy for the proposed converter is deep developed, and analytic expression between the switches state and loop circuit voltage/current condition is derived out. Hence, the current/voltage ripple can be avoided without a loss snubber circuit, which benefits a reduced cost and enhanced reliability. The performance analysis is discussed in consideration of parasitic resistance, and system parameter design is optimized based on theoretic calculation. A laboratory prototype is fabricated, and experiments are performed to verify the validation of the proposed converter. [ABSTRACT FROM PUBLISHER]

The control loop stability in boost converters operating in continuous conduction mode has been restricted due to its nonminimum phase nature: the presence of a positive zero (right-half plane zero) in the control to output voltage transfer function. This paper proposes a method to mitigate the effect of the zero on the control loop by shifting the position of the zero to the left-half plane and hence leading to increased stability for the control loop of the boost converter. Superior performance of the proposed method has been clearly demonstrated using simulation and experimental results. [ABSTRACT FROM PUBLISHER]

In this paper, a new nonisolated high-voltage-gain boost converter is proposed. The proposed converter is constructed by adding an additional inductor to a conventional three-level-boost (TLB) converter. When compared with the conventional boost and TLB converters, the proposed converter can achieve higher voltage conversion ratio with reduced voltage and current stresses in the switches. In particular, the proposed converter can reduce the losses of active devices by reducing the current of the switch compared to conventional converters, thus, can achieve high efficiency. In addition, the proposed converter automatically balances the output voltages for an unbalanced load without the need for any additional control strategy or auxiliary circuit. A 2-kW prototype converter was built and tested to verify performances of the proposed converter. [ABSTRACT FROM PUBLISHER]

In this paper, we propose a Lyapunov-function-based controller for the flyback converter operating in the continuous conduction mode (CCM). The controller consists of a duty-ratio feedforward control unit and a Lyapunov-function-based feedback control unit. The duty-ratio feedforward signal is used to reduce the burden from the Lyapunov feedback controller. The control system guarantees global exponential stability of the closed-loop system and, hence, offers fast transient response under large-signal perturbations. In constructing the controller, we use the average model of the flyback CCM converter taking the parasitic components into account. Numerical simulations confirmed its superior performance, and experimental tests validated the proposed control approach. [ABSTRACT FROM PUBLISHER]

In this paper, a power factor correction (PFC)-based switched reluctance motor (SRM) drive is proposed. Generally, the SRM drive is fed with a simple diode bridge rectifier followed by a bulky capacitor, which draws peaky current at low power factor and high-input-current total harmonic distortion (THD). Here, a dual output converter is proposed to control the SRM and to provide power quality improvement as well. This converter is a combination of Cuk and SEPIC converters, which produces two equal output voltages with neutral point N, to feed a midpoint converter of the SRM drive. The converter is designed to operate in discontinuous conduction mode of operation to obtain inherent PFC at supply side. The motor control is attained by regulating dc link voltage over a wide range. Test results on a prototype of the SRM drive demonstrate the excellent performance with high power factor and reduced input current THD. The observed power quality indices depict the improved power quality as per the standard IEC 61000-3-2. [ABSTRACT FROM PUBLISHER]

The parallel three-phase grid-connected converters sharing dc and ac bus can increase the system power level effectively. However, the circulating current will occur inevitably. The existing studies primarily focus on dc, fundamental, and low-frequency circulating current. The high-frequency circulating current (HFCC) caused by asynchronous carriers is studied emphatically in this paper, which is based on the analysis of the change of circulating current in one control cycle. A novel method to suppress HFCC caused by asynchronous carriers of modules is proposed. In this method, the carrier period of slave module is adjustable and the carrier period of the master module is constant. When a large phase shift between modules occurs, an adjusting cycle is inserted to carrier of slave module to realize resynchronizing with master module. It is noted that there is no other commutation between the two modules (expect the dq current reference), such as the carrier information. Finally, the feasibility and effectiveness of the proposed method are verified by experiments. [ABSTRACT FROM PUBLISHER]

Three-level buck dc–dc converters have advantages over the traditional buck converters: half switch voltage stress, doubling effective switching frequency, smaller inductor size, and the higher power density. To benefit from those advantages, the flying capacitor voltage must be balanced at half of the input voltage. Most existing methods of balancing the flying capacitor voltage require current sensing, which increases the cost and noise sensitivity. This paper proposes a novel state-machine structure of second-order sliding-mode (SOSM) control for three-level buck dc–dc converters without sensing currents. With insensitivity to parameter variations of SOSM control, the proposed control approach tackles the strongly coupled problem of output voltage and flying capacitor voltage in three-level buck dc–dc converters. Compared to existing approaches, the controller achieves fast start-up without overshoots, fast load disturbances rejection, and robustness against parameter uncertainties for the output voltage, and balance of the flying capacitor voltage without sensing the current of flying capacitor. The proposed approach is verified with experimental results of a 1.25 V, 2.5 A prototype. [ABSTRACT FROM PUBLISHER]

This paper proposes a single-stage light-emitting diode (LED) driver based on an inverted buck topology, using current path control switches. The proposed circuit consists of a control circuit, a bridge diode, and an inverted buck converter with multiple switches connected to the LED segments in parallel. Whereas the typical buck LED driver operates with a fixed LED forward voltage, the proposed driver operates with a variable LED forward voltage, according to the input voltage level. Because of this capability to adjust the LED forward voltage, it can reduce the current ripple and the switching frequency with a small inductance value. In addition, it enables operation with LED lamps of a wide voltage range, while simultaneously achieving small dead-angles. The detailed operation principles are described, and the design considerations for the proposed driver are discussed. The proposed driver circuit and control operation are verified experimentally using a 7 W hardware prototype with four LED segments. The obtained experimental results show that under a 110 Vrms input voltage, the proposed driver achieves a power factor of 0.94 with a small dead-angle and an efficiency of 94%. [ABSTRACT FROM PUBLISHER]

In this paper, a new type of matrix converter (MC) also called a single-phase high-frequency transformer isolated (HFTI) buck MC is proposed. The proposed converter can provide step-down operation of the input voltage with various types of output voltages such as in-phase and out-of-phase output voltages, rectified (or positive) output voltage, and output voltage with step-changed frequency. By incorporating HFT isolation, the proposed MC saves an extra bulky line frequency transformer, which is required for the conventional MCs to provide electrical isolation and safety, when used in application such as dynamic voltage restorers, etc. Two different circuit variations of the proposed HFTI MC are presented with and without continuous output currents, with the latter having less passive components. The safe-commutation strategy is also employed for the proposed HFTI MC to provide current path for the inductor during dead-time, which avoids switch voltage spikes without adding any snubber circuits. The operation principle and circuit analysis of the proposed MC are presented, and switching strategies are also developed to obtain various output voltages. Moreover, a prototype of the proposed MC is fabricated, and experiments are performed to produce in-phase/out-of-phase and rectified output voltages, and output voltage with step-changed frequency. [ABSTRACT FROM PUBLISHER]

This paper presents a new buck–boost converter. Unlike the single-switch buck–boost converter, the proposed converter has low-voltage stresses on semiconductors. Moreover, although both the conventional two-switch buck–boost (TSBB) and the proposed converters have the same number of passive and active components, and the proposed converter can reduce the conduction loss as a result of having fewer conducting components. Therefore, the proposed converter obtained a higher efficiency than the TSBB converter. A 48-V output voltage and 150-W output power prototype was fabricated to verify the effectiveness of the proposed converter. [ABSTRACT FROM PUBLISHER]

A fixed-frequency pulse width modulation (PWM) controlled bidirectional current-fed series-resonant converter is proposed in this paper. The proposed bidirectional resonant converter is derived based on integration of a bidirectional boost/buck converter and a dual-active-bridge series-resonant converter. The most attractive feature of the proposed bidirectional resonant converter is that its voltage gain is only determined by the duty cycle of primary-side switches and has nothing to do with the transferred power. Therefore, the direction and amplitude of the transferred power can be easily regulated continuously and smoothly. In addition, with the help of an auxiliary inductor, zero voltage switching can be achieved for all the active switches on both primary and secondary sides within the entire operation range. Furthermore, the converter is suitable for wide voltage applications because its voltage gain can be regulated in a wide range. The operational principles and characteristics of the proposed bidirectional resonant converter are analyzed in detail. The feasibility and effectiveness of the proposed converter are fully verified by the experimental results from a 1.6 kW prototype. [ABSTRACT FROM AUTHOR]

Single-phase power factor correction (PFC) ac–dc converters are widely used in the industry for ac–dc power conversion from single phase ac-mains to an isolated output dc voltage. Typically, for high-power applications, such converters use an ac–dc boost input converter followed by a dc–dc full-bridge converter. A new ac–dc single-stage high-power universal PFC ac input full-bridge, pulse-width modulated converter is proposed in this paper. The converter can operate with an excellent input power factor, continuous input and output currents, and a non-excessive intermediate dc bus voltage and has reduced number of semiconductor devices thus presenting a cost-effective novel solution for such applications. In this paper, the operation of the proposed converter is explained, a steady-state analysis of its operation is performed, and the results of the analysis are used to develop a procedure for its design. The operation of the proposed converter is confirmed with results obtained from an experimental prototype. [ABSTRACT FROM PUBLISHER]

By establishing the mathematical model of the current stress of the isolated bidirectional dc–dc converter (IBDC), this paper comparatively analyzes the performances of IBDC under traditional single-phase-shift control and dual-phase-shift (DPS) control. On this basis, this paper proposes a current-stress-optimized switching strategy for IBDC with DPS control, and the corresponding control scheme is designed and implemented. The current-stress-optimized switching strategy can minimize the current stress, improve the system efficiency, and increase system power capability, and these performances are particularly effective for operation conditions with high voltage conversion ratio and light load. At last, experimental results verify the excellent performance of the current-stress-optimized switching strategy and correctness of the theoretical analysis. [ABSTRACT FROM PUBLISHER]

A new three-phase single-stage rectifier is proposed in this paper. The outstanding features of the proposed rectifier are that it can produce input currents that do not have deadband regions and an output current that can be continuous when the converter is operating from maximum load to at least half of the load. In this paper, the operation of the new converter is explained, its features and design are discussed in results, and its operation is confirmed with experimental results obtained from a prototype. [ABSTRACT FROM PUBLISHER]

In this paper, a novel discontinuous current-source driver (CSD) is proposed, in which the power MOSFET gate-source voltage is increased to more than the drive supply voltage. The proposed CSD is able to recover gate energy dissipated in a conventional driver. In comparison to the conventional gate driver, the proposed CSD achieves fast switching speed to reduce switching losses. A wide range of operating duty cycle, low circulating losses, and high Cdv/dt immunity are other features of the proposed CSD. In comparison to previous discontinuous CSDs, the special advantage of the proposed circuit is power MOSFET gate voltage boosting, which leads to reduction of Rds(on) and, thus, the conduction loss. The proposed circuit is appropriate for voltage regulators (VRs) with synchronous rectifier and also it is suitable for two-stage 48-V power pod applications and low-voltage converters. Two-stage VR for laptop computer CPUs is another application of this gate driver circuit to improve light load performance. A prototype of the circuit operating at 1 MHz is implemented, and the experimental waveforms justify the theoretical analysis. [ABSTRACT FROM PUBLISHER]

This paper presents a new buck converter with optimum-damping and dynamic-slope compensation techniques. The optimum-damping control is a well-known current control method, and the proposed dynamic-slope generator can achieve frequency compensation to prevent subharmonic oscillation. When the system is disturbed, the proposed dynamic-slope generator can stabilize the circuit in a single cycle. Hence, the dynamic-slope compensation can be used to replace traditional extra slope compensation in the optimum-damping-control circuit. The measured transient time of the load current is 2 μs from 50 to 500 mA, and 3 μs from 500 to 50 mA. The optimum-damping-control techniques can rapidly reach desired output voltage in 2–3 switching cycles. The experimental and simulation results confirm that the proposed approach can achieve the slope compensation and accelerate the transient response. The proposed converter has been fabricated with TSMC 0.18 μm CMOS 1P6M technology. The converter's operating frequency is 1 MHz, the maximum output current is 500 mA, and the peak power efficiency is 89.68% under 300-mA load current. The chip area is only 1.0376 mm × 1.0599 mm (include PADs). [ABSTRACT FROM PUBLISHER]

This paper proposes a power-factor-corrected bridgeless (BL) switched-mode power supply (SMPS) for welding applications that possesses output voltage control and current limiting feature even during extreme overloading conditions at the output terminals. Eliminating an input diode bridge rectifier minimizes conduction losses and improves thermal utilization of semiconductor devices. The front-end of the proposed SMPS consists of a BL boost converter operating in a continuous conduction mode to attain unity power factor, while at the rear end a pulse width modulation isolated full bridge dc–dc converter is used to regulate the output voltage. The design and implementation of this BL arc welding power supply (AWPS) is presented showing its fast dynamic response to supply voltage and load variations. The performance of the proposed AWPS is examined in terms of power factor, total harmonic distortion of the supply current, efficiency, and output current limit over a wide range of line/load variations. Test results confirm the effectiveness of the proposed AWPS in maintaining an impeccable power quality at utility interface apart from achieving an excellent output voltage regulation and current limiting capability. [ABSTRACT FROM PUBLISHER]

Subharmonic oscillation is widely studied in switching converters under current mode control (CMC). Its boundary of occurrence in the design parameter space is well known in the case of an infinite-bandwidth current sensor. However, in a practical implementation, either a limited-bandwidth current sensor or an additional filter is used. This could have an effect on the system dynamics particularly for relatively high switching frequencies. This paper discusses the effect of the additional dynamics due to the finite-bandwidth current sensor or the additional filter on the stability and subharmonic oscillation boundaries in switching converters under CMC. It is shown that a simplified model, taking into account the dynamics of the inductor current and the sensor/filter, is enough to obtain accurate results concerning the prediction of the occurrence of subharmonic instabilities in switched converters. Design-oriented equations describing the occurrence of subharmonic oscillations are used to show some problems related to the additional dynamics on the ramp compensator design in a single-switch dc–dc converter working in continuous conduction mode. Some proposed solutions are also discussed. Numerical simulations and experimental measurements corroborate the theoretical predictions. [ABSTRACT FROM PUBLISHER]

This paper proposes a novel family of cascade three-level (TL) ac–ac direct converters based on ac switch cells, which transfer unsteady high ac voltage with distortion into regulated sinusoidal voltage with low total harmonic distortion (THD). The topological family includes buck TL–boost, buck–boost TL, and buck TL–boost TL modes. In order to achieve a reliable TL ac–ac conversion, a double transient voltage feedback control strategy of the output voltage and the voltage across the flying capacitor is introduced in this paper. A 500-VA 220-V \pm10% 50-Hz ac/220-V 50-Hz ac prototype is presented with the experimental results to prove that the converters have four improved advantages simultaneously, including lower voltage across power switches, bidirectional power flow, low THD of output voltage, and higher input power factor. [ABSTRACT FROM AUTHOR]

This paper presents a new dual-switch control structure for an ac/dc noninverting cascaded buck–boost power factor correction converter. The proposed converter operates at a discontinuous capacitor voltage mode providing an inherent high-power factor and a zero voltage turn-off switching. Additionally, the proposed control structure enables for a nondistorted sinusoidal current for a wide range of output voltage levels. Unlike the conventional methods, a mode detector is not required and consequently there is no hard transition between buck and boost modes. Although both converter switches are controlled, only one feedback control loop is required to obtain the desired power flow at a unity power factor. The principle of operation, theoretical analysis, simulation, and experimental results of a 1.6-kW prototype grid-connected converter are presented. The results confirmed the validity of the proposed system under various operating conditions. [ABSTRACT FROM PUBLISHER]

Semiactive quadrupler rectifiers (SAQRs) are proposed in this paper to serve as the secondary rectification circuits, which make the secondary-side voltages to be controllable and help reduce current stress and conduction losses. An interleaved isolated boost converter is developed based on the proposed SAQRs. By utilizing the pulse-width modulation (PWM) plus phase-shift (PPS) control strategy, the primary- and secondary-side voltages are well matched to reduce the current values and circulating conduction losses. With the proposed SAQRs, the voltage gain is extended and the voltage stresses on power devices and passive components used in rectification circuits are reduced to the half of the high output voltage. Hence, the efficiency is improved by using a transformer with a smaller turns ratio and reduced parasitic parameters, and by employing low-voltage rating devices with better switching and conduction performance. With optimal design, lower voltage, and current stresses on the primary-side switches, minimized input current ripple can be realized. Moreover, the zero-voltage turn on switching of the active switches and the zero-current turn off switching of the diodes can be achieved over a wide load and voltage range by the proposed SAQR-based converter and the control strategy. Meanwhile, the higher voltage gain, the lower voltage, and the current stresses on power devices can be obtained with the proposed SAQR-based converter compared with passive quadrupler rectifier-based converter. The feasibility and effectiveness of the proposed SAQRs and the derived converter are verified by a 380-V output prototype. [ABSTRACT FROM PUBLISHER]

This paper presents a model predictive voltage control (MPVC) method for the single-inductor multiple-output (SIMO) dc–dc converter. The proposed MPVC method is able to solve the cross-regulation problem, which is a critical issue in SIMO dc–dc converters. The design of the proposed method including augmented state-space model, cost function, enumerated algorithm, and constraints for the SIMO dc–dc converter is discussed. Simulation for the influences of predict horizon NP, control horizon NC, and Lagrange multiplier $\lambda$ on the voltage ripple is conducted to guide the control parameters’ setting for hardware implementation. Steady-state operation and dynamic performance of the proposed MPVC method are conducted in simulation and experiment based on the single-inductor dual-output (SIDO) buck converter to verify the proposed MPVC method. In addition, the comparison between the proposed method and state-of-art methods for the SIMO dc–dc converters is presented. Simulation and experimental results demonstrate that the MPVC method guarantees low cross regulation for the SIMO dc–dc converter in continuous-conduction mode (CCM) and has a fast response speed to variations in load and reference. [ABSTRACT FROM PUBLISHER]

Compared with constant duty cycle-controlled discontinuous conduction mode (DCM) boost power factor (PF) correction (PFC) converter, constant duty cycle-controlled quadratic DCM–DCM boost PFC converter features with much lower second-order line frequency output voltage ripple, and however, it suffers from low PF. To increase PF of quadratic DCM–DCM boost PFC converter, a variable duty cycle control technique for quadratic DCM–DCM boost PFC converter is presented in this paper. An approximation equivalent for the variable duty cycle is employed to simplify the implementation circuit. The corresponding expressions of PF and output voltage ripple are analyzed. For input voltage range of 100–240 Vac, quadratic DCM–DCM boost PFC converter with variable duty cycle control benefits with very high PF, and tradeoff between PF and output voltage ripple of this converter is analyzed. Experimental results from 100-W prototypes are given to verify the theoretical analysis. [ABSTRACT FROM PUBLISHER]

For interleaved boost-type converters, both functions of voltage regulation and current balance are important. In this paper, the decoupled current-balancing control (DCBC) with two parallel loops is proposed. At first, the small-signal transfer functions of the voltage-regulation loop and the current balancing loop to the controller output are derived. The results show that the voltage-regulation loop and the proposed current-balancing loop are nominally decoupled. That is, two PI-type controllers can be designed independently and included to implement the proposed DCBC. Additionally, the single-sensor sampling-current strategy is proposed to obtain two average inductor currents by sensing only the sum of diode currents. All the controllers are implemented in field-programmable gate array (FPGA). The provided simulation and experimental results demonstrate the proposed DCBC. [ABSTRACT FROM PUBLISHER]

It is known that the ripple-based control of a switching dc–dc converter benefits from a faster transient response than a conventional pulse width modulation (PWM) control switching dc–dc converter. However, ripple-based control switching dc–dc converters may suffer from fast-scale oscillation. In order to achieve fast transient response and ensure the stable operation of a switching dc–dc converter over a wide load range, based on a conventional pulse train (PT) control technique, a peak capacitor current PT (PCC-PT) control technique is proposed in this paper. With a buck converter as an example, the operating modes, steady-state performance, and transient respond performance of a PCC-PT controlled buck converter are presented and assessed. To eliminate fast-scale oscillation, circuit and control parameter design considerations are given. An accurate discrete iteration model of a PCC-PT controlled buck converter is established, based on which the effects of circuit parameters on the stability of the converter operating in a discontinuous current mode (DCM), mixed DCM-continuous conduction mode (CCM), and CCM are studied. Simulation and experimental results are presented to verify the analysis results. [ABSTRACT FROM PUBLISHER]

In this paper, a novel grid-connected high step-up inverter is proposed. The topology is composed of two stages. The first stage is a single-switch high step-up dc–dc converter with bipolar outputs, and the second stage is a conventional half-bridge dc–ac grid-connected inverter. Negative grounding of the photovoltaic (PV) module has resulted in elimination of unwanted ground leakage currents in the PV system. Simple structure, employing few semiconductor switches, simple control, and high efficiency are the features of the proposed topology. Theoretical analysis and principal operation of the circuit are discussed. An experimental prototype is implemented to verify the performance of the proposed inverter. The experimental results confirm the aforementioned features and the theoretical analysis of the converter operation. [ABSTRACT FROM PUBLISHER]

A three-phase single-switch discontinuous conduction mode (DCM) boost power factor correction (PFC) converter features zero-current turn on for the switch, no reverse recovery in the diode, a constant-switching-frequency operation, a simple control, and a low cost, which are suitable for low-to-medium-power and cost-sensitive applications. Due to the DCM, the energy transfer does not cover the whole switching cycle, the rms and peak values of the inductor current are large, and those of the switch and the diode are also large. This increases not only the current stress of the power components but also the conduction and switching turn-off losses, which lower the efficiency of the converter. An optimum utilization control of switching cycles is proposed in this paper to increase the critical boost inductance. The rms and peak current values of the main power components are reduced, and the conduction and switching turn-off losses are therefore decreased, leading to higher efficiency. The proposed method also slightly achieves an output voltage ripple reduction, and the input current harmonics comply with the standard of the International Electrotechnical Commission 61000-3-2 Class A. [ABSTRACT FROM AUTHOR]

Carrier-based pulsewidth-modulation (CBPWM) techniques are popular due to their simplicity, and have been widely researched for various three-phase inverter configurations. In this paper, two CBPWM techniques are proposed to reduce the common-mode (CM) voltage generated by the five-phase inverter. The five-phase inverters have more flexibility in reducing the CM voltage than their three-phase counterparts because they have more phase legs, hence finer control over the star-point voltage of the load. Two methods are proposed for the conventional two-level five-phase inverter to reduce the CM voltage; one utilizing adjacent modulating waveforms and the other utilizing nonadjacent modulating waveforms. The coupled inductor inverter (CII) uses coupled inductors to generate multilevel outputs. As the volt-second balance must be maintained across each coupled inductor, direct application of the proposed methods on the CII inverter will result in overcurrents in the coupled inductors. Hence, the proposed methods are further improved to ensure the volt-second integral over each switching period is zero. Moreover, the two proposed methods are designed to reduce switching events and prevent unexpected states occurring during the switching transitions. The performance and the switching strategy of both methods are verified by both simulations and experiments on a prototype of five-phase CII. [ABSTRACT FROM AUTHOR]

For discontinuous conduction mode (DCM) dc–dc converters with digital sensorless current mode (DSCM) control, an observed current error occurs, owing to a low-accuracy current observer. Moreover, a reference current error occurs due to a low-accuracy current controller or a finite dc gain of current loop. Conventionally, the observed current is compensated to increase current regulation accuracy, whereas the reference current error is neglected. However, for charge balance principle (CBP)-based DSCM (CBP-DSCM) control, this paper proves that the reference current should be compensated in a same quantity to that of observed current. Otherwise, single or unequal compensation leads to output voltage steady-state error. For this reason, a dual current error compensation strategy for CBP-DSCM control is proposed. It compensates the errors in a same quantity through a current error observer, which considers parasitics and calculates the current errors without approximation. To verify the proposed strategy, small-signal models with parasitics for both the converter and the controller are constructed by differential functions of key variables. Furthermore, converter stability is analyzed at typical operation condition, while the stability at various operation conditions is verified through robustness analysis. Finally, simulations and experimental results verify the analysis and the improved transient response of the converter. [ABSTRACT FROM AUTHOR]

This paper presents high step-up dc-to-dc converter for low voltage sources such as solar photovoltaics, fuel cells, and battery banks. To achieve high voltage gain without large duty cycle operation, combination of coupled inductor and switched capacitor voltage doubler cells are used. By incorporating active clamp circuit, voltage spike due to the leakage inductance of the coupled inductor is alleviated and zero-voltage switching turn on of the main and auxiliary switch is obtained. Due to the use of MOSFETs of low voltage rating and soft turn on of the switches, conduction loss and switching losses are reduced. This improves the efficiency and power density of the converter. The proposed converter can achieve high voltage gain with reduced voltage stress on MOSFET switches and output diodes. Design and analysis of the proposed converter is carried out, and finally, a 500-W experimental prototype is built to verify theoretical analysis. [ABSTRACT FROM PUBLISHER]