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Automotive embedded electronic systems have been increasing in power and complexity and, therefore, more advanced power electronic converters are necessary in these vehicles. Several dual-voltage (42 V/14 V) bidirectional converter architectures have been proposed for automotive systems in recent years. However, most of them have low efficiency or are based in series and parallel configurations with large number of semiconductors and magnetics devices. Therefore, in this paper, we propose a bidirectional high-efficiency converter with lower number of components. This converter was created by merging a switched-capacitor converter and a conventional bidirectional converter, resulting in a hybrid topology. The voltage across the semiconductors of the proposed converter is equal to half of the highest voltage source value. Furthermore, the topology is composed of only one inductor to control the power flow between the two voltage sources. To verify all the mentioned features, a prototype was implemented experimentally, reaching a maximum efficiency of 97.5%. [ABSTRACT FROM PUBLISHER]

In battery/ultracapacitor electric vehicles, a bidirectional dc/dc converter is employed to process the power according to the power references obtained from the energy management controller. The selection of this converter is of critical importance for the overall system efficiency and size. This study proposes using a three-level dc/dc converter and provides a comprehensive comparison with the conventional two-level and interleaved bidirectional buck/boost converters in terms of magnetic component size/weight and overall efficiency. Unlike the comparative studies presented in the literature, where the efficiency comparison of converters is conducted based on given fixed input and output parameters, power references obtained from a wavelet-transform-based energy management strategy with varying energy source voltages and traction power are considered in this paper. The results of the analyses show that a three-level converter exhibits higher overall efficiency and has smaller size inductor. A 1-kW bidirectional three-level dc/dc converter is designed as a proof of concept, which exhibits 93.2% peak efficiency at 200-kHz switching frequency. [ABSTRACT FROM PUBLISHER]

The average-current-controlled boost power factor correction converter may operate in all-continuous current mode (CCM), part-CCM/discontinuous current mode (DCM), or all-DCM mode in a half line cycle under different input voltage and load conditions, and the conducted electromagnetic interference (EMI) spectrum of the converter exhibits differences in these operation modes. In this paper, by analyzing the characteristic of the harmonics of the drain-to-source voltage of the power switch, the characteristics of the common-mode and differential-mode noise of the converter are revealed in different operation modes. The analyzed results can be used to guide the EMI filter design for the converter and ensure the conducted EMI satisfying the standard under all working conditions. [ABSTRACT FROM PUBLISHER]

Power converters using deterministic switching frequency schemes have switching noise concentrated at harmonic frequencies, resulting in enhanced electromagnetic emission. To suppress the harmonic spikes in three-phase multilevel voltage source converters, a digital control scheme based on dithered sigma–delta modulation (SDM) is proposed in this paper. Introducing a dithered sequence in an SDM varies the switching frequency randomly, resulting in the suppression of the spurious harmonic spikes in the output spectrum even with a regular control input. Although the switching frequency varies randomly, the minimum pulsewidth of the proposed scheme is the sampling time period, avoiding the minimum pulsewidth problem. Instead of a conventional scalar quantizer, the quantizer in the proposed dithered sigma–delta converter uses the principle of space vector quantization. The proposed scheme is experimentally verified on a constant $v/f$ open-loop induction motor drive for a three-level inverter realized by cascading two two-level inverters. The performance of the proposed scheme is compared with different pulsewidth modulation schemes in the entire modulation index, including the overmodulation region. [ABSTRACT FROM PUBLISHER]

Grid-connected power converters play a key role in several applications such as the integration of renewable energy sources and motor drives. For this reason, the development of high performance control strategies for this particular class of power converters has increasingly attracted the interest of both academic and industry researchers. This paper presents the predictive optimal switching sequence (OSS) direct power control (DPC) (OSS-DPC) algorithm for grid-connected converters. The OSS-DPC method belongs to the predictive-DPC family and provides the desired power references by calculating globally OSSs. To address computational and implementation issues, an efficient control algorithm, named reduced OSS-DPC, is introduced. The implementation of the proposed control strategy in a standard DSP is evaluated on a two-level power converter prototype working as a STATCOM. Experimental results show the algorithm's potential to provide high performance during both transient and steady states. [ABSTRACT FROM PUBLISHER]

This paper presents a real-time diagnostic algorithm for insulated-gate bipolar transistor open-circuit faults in three-level neutral-point-clamped rectifiers. This algorithm is based on the instant voltage error in the converter and requires only signals already available to the control system, avoiding the use of additional hardware. The algorithm is independent from the load and from the used control strategy and provides very fast detection and identification of the fault, with diagnostic times as low as two sample periods (in favorable conditions). Experimental results are presented for the operation of the rectifier with two distinct control and modulation strategies and in different conditions. Results show the algorithm's speed, effectiveness, and robustness. [ABSTRACT FROM PUBLISHER]

In this paper, we review relevant problems in the modeling of dc–dc converters with switched capacitors. We study several approaches that overcome the exposed modeling difficulties, addressing ideal and nonideal cases and using dynamic equations that are valid in a large-signal domain. [ABSTRACT FROM PUBLISHER]

A single-switch nonisolated dc/dc converter for a stand-alone photovoltaic (PV)-battery-powered pump system is proposed in this paper. The converter is formed by combining a buck converter with a buck-boost converter. This integration also resulted in reduced repeated power processing, hence improving the conversion efficiency. With only a single transistor, the converter is able to perform three tasks simultaneously, namely, maximum-power-point tracking (MPPT), battery charging, and driving the pump at constant flow rate. To achieve these control objectives, the two inductors operate in different modes such that variable switching frequency control and duty cycle control can be used to manage MPPT and output voltage regulation, respectively. The battery in the converter provides a more steady dc-link voltage as compared to that of a conventional single-stage converter and hence mitigates the high voltage stress problem. Experimental results of a 14-W laboratory prototype converter with a maximum efficiency of 92% confirmed the performance of the proposed converter when used in a PV-battery pump system. [ABSTRACT FROM PUBLISHER]

In a flyback converter using the conventional valley-switching method, the switching frequency under the light load condition is higher than that under the heavy load condition, which increases the switching loss. A valley skip (VS) technique can reduce the switching frequency under the light load condition. Although it helps to reduce the switching loss, it makes the uncomfortable humming sound caused by a sudden change in switching frequency during valley change. To minimize the audible noise, a new digitally controlled soft valley change (SVC) technique is proposed in this paper. It changes the turn-on instant among valleys gradationally during several switching cycles under any transient situation. The SVC also helps to spread switching frequency so that electromagnetic interference can be reduced. The proposed technique is suitable for the applications that operate under the dynamic load condition such as an audio amplifier. The proposed technique is implemented in an integrated circuit and verified by a prototype experimental test board of 60 W/12 V. [ABSTRACT FROM PUBLISHER]

Conventional matrix converters (MCs) have limited voltage gain that is less than 0.866, whether for direct MC (DMC) or indirect MC (IMC). Existing Z-source (ZS)/discontinuous quasi-Z-source (qZS) DMCs and ZS IMCs achieved larger than 0.866 voltage gain; however, the former inherited the complex commutation from DMC, and the latter involved a ZS network in dc link and led to non-all-silicon solution. In this paper, ZS and discontinuous qZS networks of existing ZS/qZS DMCs are used for an IMC topology for simplifying commutation and having high voltage gain, but they require extra input filter to reduce current harmonics. A new continuous qZS IMC is proposed, where a qZS network integrates the filtering function of the grid side; hence, additional input filter is avoided in the proposed continuous qZS IMC. Three new IMCs are compared in detail, in terms of voltage gain, current ripple, voltage ripple, inductor current and capacitor voltage stresses, ZS/qZS switch current and voltage stresses, filtering function, input current total harmonic distortion (THD), output voltage THD, and efficiency. Their control and modulation methods are presented to achieve the desired performances. Experimental comparisons verify the theoretical analysis and that the proposed continuous qZS IMC is a promising topology. [ABSTRACT FROM PUBLISHER]

Three-level topologies are widely used in back-to-back converters of wind turbine generation (WTG) systems. In comparison with a conventional two-level topology, three-level topologies have more advantages, particularly for the high power. Neutral-point clamped (NPC) and T-type are typical three-level topologies. An open-switch fault of a three-level rectifier that is connected to a permanent-magnet synchronous generator (PMSG) leads to the current distortion and torque vibration in WTG systems. Furthermore, WTG systems can break down in the worst case. Therefore, a tolerance control for open-switch faults is required to improve the reliability of WTG systems. WTG systems by applying the tolerance control can be stopped safely and prevent additional problems. Depending on the situation, it can keep the operation of WTG systems under open-switch fault. The effects of outer open-switch faults of three-level rectifiers are analyzed by considering PMSG specifications in this paper. Moreover, a tolerance control for outer open-switch faults of the NPC and T-type three-level rectifiers are proposed with existing tolerance controls for inner open-switch faults. The proposed tolerance control is to inject the exact $d$-axis current value to eliminate current distortion. The simulation and experiment are conducted to prove the feasibility of the proposed tolerance control and to identify its performance. [ABSTRACT FROM PUBLISHER]

Affected by the equivalent series resistance (ESR) of the devices in the circuit, the voltage-conversion ratio of traditional boost converter is limited. Various topologies have been developed to provide a high step-up voltage gain. An inherent high voltage gain can be achieved in a dual-switch converter with the advantages of low voltage and current stress on the switches. However, this converter has a strict requirement of the parameters' consistency. This paper discusses the steady-state operation principle of the converter in detail under the condition that the parameters are inconsistent and then illustrates the solutions to balance the voltage on the switches and suppress the resonance with passive lossless clamping. Finally, a prototype has been established in the laboratory, and simulation and experimental results have been given to verify the analysis and the effectiveness of clamping method. [ABSTRACT FROM PUBLISHER]

This paper introduces an enhanced commutation method applied to the indirect matrix converter topology. It is based on the detection of the load current polarity so as to cancel the turn-on delay times of the load-side converter's switches. The proposed method allows the grid-side converter devices to commutate at zero current with larger time interval widths provided for this safe commutation. Moreover, it has been shown through experimental results, carried out on a laboratory prototype of the matrix converter, that a substantial improvement of line current total harmonic distortion is achieved. [ABSTRACT FROM PUBLISHER]

The industrial use of inductive power transfer (IPT) systems is becoming widespread, ranging from monorail systems, motors, people movers, and battery charging applications. This paper proposes a 3-D IPT system driven by a multiple-phase power converter. This is aided by spice circuitry simulation of the power converter, finite-element-assisted software magnetic frequency analysis, and via implementation of the proposed system. The proposed system consists of a cubic power transfer primary window generated by a rotating magnetic flux flow path. This rotating field is loosely coupled via magnetomotive force (MMF) induction into a secondary power pick-up. The system has been demonstrated as a low-power battery charging system. [ABSTRACT FROM PUBLISHER]

A variable on-time (VOT) control strategy for a critical conduction mode (CRM) flyback power factor correction (PFC) converter with low total harmonic distortion (THD) and high power factor (PF) is proposed in this paper. By using input voltage and the voltage across the auxiliary winding of the flyback transformer to modulate the turn-on time of the switch of the CRM flyback PFC converter, the PF and THD of the converter can be improved. The operation principles of the traditional constant on-time (COT)-controlled CRM flyback PFC converter and VOT-controlled CRM flyback PFC converter are analyzed. The experimental results show that the PF and THD of the VOT-controlled CRM flyback PFC converter are better than those of the COT-controlled CRM flyback PFC converter. [ABSTRACT FROM PUBLISHER]

In this paper, a dedicated pulse width modulation (PWM) technique specifically designed for single-phase (or four wire three-phase) multilevel Cascaded H-Bridge Converters is presented. The aim of the proposed technique is to minimize the DC-Link voltage unbalance, independently from the amplitude of the DC-Link voltage reference, and compensate the switching device voltage drops and on-state resistances. Such compensation can be used to achieve an increase in the waveform quality of the converter. This is particularly useful in high-power low supply voltage applications where a low switching frequency is used. The DC-Link voltage balancing capability of the method removes the requirement for additional control loops to actively balance the DC-Link voltage on each H-Bridge, simplifying the control structure. The proposed modulation technique has been validated through the use of simulation and extensive experimental testing to confirm its effectiveness. [ABSTRACT FROM PUBLISHER]

This paper presents a modulation strategy for symmetrical cascaded multilevel converters that simultaneously balances the individual DC voltages and reduces switching losses by eliminating redundant or unnecessary commutations. The voltage regulation is based on a 1-bit digital signal indicating whether the DC link voltage of each H-bridge is above or below the set point. The system command identifies commutations that can be suppressed without causing output voltage distortion, thus reducing converter losses. The voltage balancing is reached by postponing each switching commutation for a short lapse of time. Simulation and experimental results for an active filter application validate the proposed methods. [ABSTRACT FROM PUBLISHER]

Multilevel converters are known to have many advantages for electricity network applications. In particular, cascaded H-bridge converters are attractive because of their inherent modularity and scalability. Predictive control for power converters is advantageous as a result of its applicability to discrete system and fast response. In this paper, a novel control technique, named modulated model predictive control, is introduced with the aim to increase the performance of model predictive control. The proposed controller addresses a modulation scheme as part of the minimization process. The proposed control technique is described in detail, validated through simulation and experimental testing, and compared with dead-beat and traditional model predictive control. The results show the increased performance of the modulated model predictive control with respect to the classic finite control set model predictive control in terms of current waveform total harmonic distortion (THD). Moreover, the proposed controller allows a multi-objective control, with respect to dead-beat control that does not present this capability. [ABSTRACT FROM PUBLISHER]

In this paper, an effective output voltage control method using adjustable frequency–duty-cycle hybrid control is presented. By using the proposed method, the operating performance of the full-bridge series resonant dc–dc converter applied to the onboard charger in electric vehicles under the constant-voltage charge mode is improved. The proposed control method improves the system efficiency of the charger up to 4% for light load conditions compared with the conventional control method without any extra hardware. A theoretical analysis is described along with a loss analysis in detail, and the validity of the proposed method is verified by experiment with a 3.3-kW prototype onboard charger. [ABSTRACT FROM PUBLISHER]

This paper presents a boost converter with a proposed tapped inductor ripple cancellation network. Based on the conventional boost converter (CBC), a small capacitor and a small inductor are added as the ripple cancellation network (RCN) in the proposed converter. Meanwhile, the tapped inductor can be easily realized by adding an extra tap in the main inductor of the CBC. Since the capacitor and inductor in the RCN do not need to handle the main power as the conventional LC input filter, the size and weight of the proposed converter are relatively small comparing the CBC with the LC input filter. The small signal and dynamic characteristics analyses show that the proposed converter has the same static and dynamic responses as the CBC, and the input current ripple cancellation can be achieved in all power ranges without significantly increasing the losses. Finally, three 36–50-V, 500-W prototypes operating at 100 kHz are implemented to verify the expected performance. The simulation and experimental results show that the proposed converters can achieve input current ripple cancellation with efficiency higher than 97.4% in all power ranges. [ABSTRACT FROM PUBLISHER]

Overcurrent protection of silicon carbide (SiC) metal–oxide–semiconductor field-effect transistors (MOSFETs) remains a challenge due to lack of practical knowledge. This paper presents three overcurrent protection methods to improve the reliability and overall cost of SiC MOSFET-based converters. First, a solid-state circuit breaker (SSCB) composed primarily by a Si IGBT and a commercial gate driver IC is connected in series with the dc bus to detect and clear overcurrent faults. Second, the desaturation technique using a sensing diode to detect the drain-source voltage under overcurrent faults is implemented as well. Third, a novel active overcurrent protection scheme through dynamic evaluation of fault current level is proposed. The design considerations and potential issues of the protection methods are described and analyzed in detail. A phase-leg configuration-based step-down converter is built to evaluate the performance of the protection schemes under various conditions, considering variation of fault type, decoupling capacitance, protection circuit parameters, etc. Finally, a comparison is made in terms of fault response time, temperature-dependent characteristics, and applications to help designers select a proper protection method. [ABSTRACT FROM PUBLISHER]

In this paper, novel topologies for symmetric, asymmetric, and cascade switched-diode multilevel converter are proposed, which can produce many levels with minimum number of power electronic switches, gate driver circuits, power diodes, and dc voltage sources. The number of required power electronic switches against required voltage levels is a very important factor in designing of multilevel converter, because switches define the reliability, circuit size, cost, installation area, and control complexity. For asymmetric and cascade converter, new algorithms for determination of dc voltage sources values are presented. To produce maximum number of levels at the output voltage, the proposed cascade topology is optimized for different goals, such as the minimization of the number of power electronic switches, gate driver circuits, power diodes, dc voltage sources, and blocking voltage on switches. Comparison of the results of various multilevel converters will be investigated to reflect the merits of the presented topologies. The operations of the proposed multilevel converters have been analyzed with the experimental and simulation results for different topologies. Verification of the analytical results is done using MATLAB simulation. [ABSTRACT FROM PUBLISHER]

This paper presents a single-phase transformerless grid-connected photovoltaic converter based on two cascaded full bridges with different dc-link voltages. The converter can synthesize up to nine voltage levels with a single dc bus, since one of the full bridges is supplied by a flying capacitor. The multilevel output reduces harmonic distortion and electromagnetic interference. A suitable switching strategy is employed to regulate the flying-capacitor voltage, improve the efficiency (most devices switch at the grid frequency), and minimize the common-mode leakage current with the help of a novel dedicated circuit (transient circuit). Simulations and experiments confirm the feasibility and good performance of the proposed converter. [ABSTRACT FROM PUBLISHER]

Alternating current (ac) active electronic loads (AELs) based on pulsewidth modulation (PWM) converters, capable of emulating nonlinear loads, require effective current control techniques and power stages. These two aspects of an AEL are interdependent mainly due to the presence of electromagnetic compatibility filters to reduce electromagnetic emissions. However, the filter components affect the dynamics of the system. In this context, this paper proposes a digitally implemented control strategy comprising the state feedback, robust observer, phase-locked loop, and linear current controller to cope with ac AEL applications. The control-oriented modeling and the control system design are presented. Experimental results obtained from a 10-kW three-phase three-level PWM converter prototype illustrate and demonstrate the feasibility of the proposed AEL control strategy. [ABSTRACT FROM PUBLISHER]