Voltage Stress Of Switching Devices Research Articles

Single-Switch High Step-Up DC-DC Converter with a Resonant Voltage Doubler and low Duty Ratio

High voltage gain can be easily achieved by utilizing a coupled inductor, but high voltage stresses of switching devices can result from its leakage inductance. Hence, snubber circuits are required to alleviate voltage stresses but these can generally lead to power losses. In this paper, a single-switch high step-up DC-DC converter with a coupled inductor and low duty ratio is proposed. A resonant voltage doubler is integrated to obtain higher voltage gain. Zero-current-switching (ZCS) for the diodes in the voltage doubler is achieved by exploiting resonance of the leakage inductance. Additionally, there is no surge voltage in any of the switching device and this makes dissipative snubber circuits unnecessary. Furthermore, maximum voltage stresses of switching devices are much lower than the output voltage and high voltage gain with low duty ratio can be obtained due to the modified cascade boost structure. All this helps to improve overall power efficiency. The operational principle and characteristics of the proposed converter is provided in detail. Experimental investigation using an output 400V-140W prototype at an input 24V- 48V is conducted to verify its functionality.

Shoot-Through Control-Based Space Vector Modulation Approach for a Modified Z-Source NPC Power Inverter

Z-source Neutral Point Clamped (NPC) inverter is a converter topology that combines the benefits of both the impedance network by storing temporary energy released to the load for voltage boosting and NPC inverter by guaranteeing lower Total Harmonic Distortions (THDs) and reducing voltage stresses of switching devices. In this context, this paper deals with a modified three-level Z-source NPC inverter topology with simplified command to generate shoot-through states and reduce switching losses. For this reason, an extra power switch Insulated Gate Bipolar Transistor (IGBT) is added to insert shoot-through, thus eliminating the need for full-shoot-through on any of the three branches of the inverter. On the other hand, a modified Space Vector Modulation (SVM) strategy is proposed. This gives a number of benefits, both in terms of implementation and harmonic performance. Effectiveness of the proposed topology is verified through simulations using Matlab toolbox Simulation and laboratory experiment.

A Commutation Torque Ripple Suppression Strategy for Brushless DC Motor Based on Diode-Assisted Buck–Boost Inverter

Based on diode-assisted buck–boost inverter, this paper proposes a new commutation torque ripple suppression strategy for brushless dc motor (BLDCM). Four types of switching vectors are constructed, according to the working pattern of the diode-assisted inverter and the operation mode of the BLDCM. Moreover, the effects of switching vector combination on commutation torque ripple suppression and motor speed regulation are analyzed in the commutation and normal conduction periods, respectively. Based on this analysis, the duration of switching vectors within each modulation cycle is derived and the sequence of vectors is arranged at the same time in these two periods. The proposed method can effectively suppress the commutation torque ripple over the full speed range by unified switching vectors during the commutation period, without needing to switch control strategies according to the speed range. In addition, the increase of the voltage stress of switching devices in the inverter bridge can be avoided by designing the duration and sequence of switching vectors during the commutation and normal conduction periods. The effectiveness of the presented method is validated by the experimental results.

A Single-Phase Three-Level Flying-Capacitor PFC Rectifier Without Electrolytic Capacitors

A component-minimized and low-voltage-stress single-phase power factor correction rectifier without electrolytic capacitor is proposed in this paper. Component minimization is achieved by embedding an active pulsating-power-buffering (PPB) function within each switching period, such that typical add-on power electronic circuits for PPB are no longer needed. Additionally, with a three-level flying-capacitor configuration, the voltage stresses of switching devices can be reduced more than 50% as compared to existing solutions that are based on embedded PPB. The relationship between the inductance requirement and the patterns of the modulation carriers, and how it can be utilized to minimize the magnetics of the rectifier, is also discussed. A 110 W hardware prototype is designed and tested to demonstrate the feasibilities of the proposed rectifier. An input power factor of more than 0.97, peak efficiency of 95.1%, and an output voltage ripple of less than 4.3% across a wide load range have been experimentally obtained.

SiC Stacked-Capacitor Converters for Pulse Applications

Pulse power converters demands single high voltage and current pulse shape waveform in high temperature, heavy neutrons, and ions radiation environment, where ${\text{50}}\% \sim {\text{75}}\%$ voltage derating margin is typically required for the power devices. silicon carbide (SiC) mosfet s are promising to improve radiation reliability owing to wide band-gap. However, the conventional converters with off-the-shelf commercial SiC mosfet s cannot provide enough voltage margin accordingly. A stack-capacitor pulse converter topology is proposed to reduce the voltage stress of switching devices and capacitors and improve the voltage derating capability significantly. The main idea is to build high voltage with multiple low voltage stacks instead of single high voltage capacitors, so that SiC mosfet s can be applied with improved voltage margin. The method is to charge the stack-capacitors in parallel with fast charging speed, and discharge in series for high pulse voltage. The converter operates at higher switching frequency, which reduces the weight and size of the magnetic components. A 300-kHz prototype with 18–28 V input and 1 kV/ 100 A output was built using 650 V SiC devices, demonstrating 75% reduction of the voltage stress of the capacitors and power devices compared with the conventional converters.

A PWM Strategies for Diode Assisted NPC-MLI to Obtain Maximum Voltage Gain for EV Application

The projected diode assisted Neutral Point Diode Clamed (NPC-MLI) with the photovoltaic system produces a maximum voltage gain that is comparatively higher than those of other boost conversion techniques. This paper mainly explores vector selection approach pulse-width modulation (PWM) strategies for diode-assisted NPC-MLI to obtain a maximum voltage gain without compromising in waveform quality. To obtain a high voltage gain maximum utilization of dc-link voltage and stress on the power switches must be reduced. From the above issues in the diode assisted NPC-MLI leads to vector selection approach PWM technique to perform capacitive charging in parallel and discharging in series to obtain maximum voltage gain. The operation principle and the relationship of voltage gain versus voltage boost duty ratio and switching device voltage stress versus voltage gain are theoretically investigated in detail. Owing to better performance, diode-assisted NPC-MLI is more promising and competitive topology for wide range dc/ac power conversion in a renewable energy application. Furthermore, theoretically investigated are validated via simulation and experimental results.

Minimum Flying Capacitor for <italic>N</italic>-Level Capacitor DC/DC Boost Converter

This paper proposes a multilevel flying capacitor dc/dc boost converter (FCBC) with a small capacitance of the flying capacitor for the reduction of converter size. In this paper, the design methods for the boost inductor and the flying capacitor in the n -level FCBC are principally and experimentally confirmed. Furthermore, the boost inductor is designed based on maximum product of voltage-time, regardless the number of level. Meanwhile, the minimum capacitance of the flying capacitor is designed based on the maximum switching device voltage stress, regardless of the output voltage ripple influences. Moreover, the achieved maximum efficiency of the designed three-level FCBC is 98.5% at the output power of 1 kW. Finally, the effectiveness of small capacitances of the flying capacitor in the three-level and five-level FCBCs is analyzed. The characteristics of the distorted voltage across the input voltage source and the boost inductor, and the distorted current to the output side (output capacitor and load) are investigated with several capacitances of the flying capacitors in the three-level and five-level FCBCs. As a result, it is experimentally confirmed that the distorted voltage is drastically reduced by increasing the number of level. Besides, the distorted current is almost the same although the number of level is increased. Therefore, based on the experimental results, it is shown that small capacitance of the flying capacitor can be used in the n -level FCBC without compromising the stability of converter operation.

A Single-Phase PV Quasi-Z-Source Inverter With Reduced Capacitance Using Modified Modulation and Double-Frequency Ripple Suppression Control

In single-phase photovoltaic (PV) system, there is double-frequency power mismatch existed between the dc input and ac output. The double-frequency ripple (DFR) energy needs to be buffered by passive network. Otherwise, the ripple energy will flow into the input side and adversely affect the PV energy harvest. In a conventional PV system, electrolytic capacitors are usually used for this purpose due to their high capacitance. However, electrolytic capacitors are considered to be one of the most failure prone components in a PV inverter. In this paper, a capacitance reduction control strategy is proposed to buffer the DFR energy in single-phase Z-source/quasi-Z-source inverter applications. Without using any extra hardware components, the proposed control strategy can significantly reduce the capacitance requirement and achieve low input voltage DFR. Consequently, highly reliable film capacitors can be used. The increased switching device voltage stress and power loss due to the proposed control strategy will also be discussed. A 1-kW quasi-Z-source PV inverter using gallium nitride (GaN) devices is built in the lab. Experimental results are provided to verify the effectiveness of the proposed method.

Efficient bridgeless PFC converter with reduced voltage stress

SummaryAn efficient bridgeless power factor correction converter with reduced voltage stress is proposed. In the proposed converter, the input full‐bridge rectifier is removed to reduce the conduction loss of rectification, and the voltage stress of switching devices is significantly reduced by utilizing the additional circuit composed of a capacitor and a diode. Therefore, low‐voltage‐rating diodes with less forward voltage drop and low‐voltage‐rating Metal‐Oxide‐Semiconductor Field‐Effect Transistor (MOSFET) with low RDS(on) is utilized. The proposed converter is based on the single‐ended primary‐inductor converter power factor correction operation in discontinuous conduction mode to achieve a high power factor with a simple control circuit. Consequently, the proposed converter can provide a high power factor and a high power efficiency, and it is also suitable for low‐cost converter for high input/output voltage system. The operational principles, steady‐state analysis, and design equations of the proposed converter are described in detail. Experimental results are verified for a 130 W prototype at a constant switching frequency 100 kHz. Copyright © 2015 John Wiley & Sons, Ltd.

개선된 비절연형 3-레벨 고승압 부스트 컨버터

In this paper, an improved non-isolated 3-level high step-up boost converter is proposed. By using the well known duality principle, the proposed converter is derived from two-phase buck converter. Compared with the traditional boost converter and 3-level boost converter, the proposed converter can obtain very high voltage conversion ratio and the voltage stress of switching devices and diodes is only 1/4 of the output voltage. A 1 kW prototype converter is built and tested to verify performances of the proposed converter.

Improved Pulse-Width Modulation Strategies for Diode-Assisted Buck–Boost Voltage Source Inverter

The recently proposed diode-assisted buck–boost voltage source inverter (VSI) enhances the voltage boost capability greatly without extreme large boost duty ratio, which is more suitable for wide range voltage regulation in dc/ac power conversion. This paper mainly explores pulse-width modulation (PWM) strategies for diode-assisted buck–boost VSI and their relationship of voltage gain versus voltage boost duty ratio. In view of variable intermediate dc-link voltage, two kinds of improved PWM strategies with high dc-link voltage utilization are presented to obtain the maximum linear voltage gain in theory, as well as to minimize the voltage stress of switching devices. The operation principle, and the relationship of voltage gain versus voltage boost duty ratio and switching device voltage stress versus voltage gain are analyzed in detail. The related simulation and experiments are implemented to verify the theoretical analysis. Compared with existing counterparts, diode-assisted buck–boost VSI with improved PWM strategies demonstrates good performances: less switching device requirement and higher efficiency at high voltage gain. Owing to improved performance, diode-assisted buck–boost VSI is more promising and competitive topology for wide range dc/ac power conversion in a renewable energy application. Furthermore, the idea of improved modulation strategies can also be extended to the control of diode-assisted buck–boost current source inverter.

Analysis and implementation of an interleaved series input parallel output active clamp forward converter

A novel dual active clamp forward topology with interleaved series input parallel output (ISIPO) structure is proposed here. The ISIPO active clamp forward converter enables the converter cells to share the input voltage and output current. The interleaved operation can diminish the output current ripple in the output capacitor. The output capacitance of switching devices and the resonant inductance are utilised to realise the resonance at the transition interval of switches such that the zero-voltage-switching operation for all switches can be achieved. Moreover, the energy stored in the transformer leakage inductance is recycled such that the voltage stresses of switching devices are reduced. All these features make the proposed converter suitable for the DC-DC converters with high input voltage, high output current and high-efficiency applications. The operating principle and design considerations are provided in detail. Finally, experimental results based on a 240 W(12 V/20 A) prototype with an input voltage of 400 V are presented to verify the theoretical analysis and circuit performance.

電圧クランプＺＶＳ‐ＰＷＭ双方向ＤＣ‐ＤＣコンバータ

This paper proposes an isolated bidirectional DC-DC converter that is suitable for use in a low-voltage, large -current battery integrated photovoltaic(PV) system. The proposed converter comprises an asymmetrical half-bridge and current-driven rectification circuit with a center-tap transformer. The voltage stress of switching devices is suppressed by zero-voltage switching (ZVS) of the half-bridge circuit on the primary side, and synchronous rectification on the secondary side reduces conduction losses. In addition, the proposed circuit is capable of current boost operation by using synchronous rectifier on the secondary side. Voltage clamp circuits suppress the stray resonance and voltage surge during the battery charge and discharge mode. ZVS operation of all switching devices and the effectiveness of the voltage clamp circuits are confirmed through PSpice simulation.

Single-Stage Soft-Switching Converter With Boost Type of Active Clamp for Wide Input Voltage Ranges

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A single-stage soft-switching converter is proposed for universal line voltage applications. A boost type of active-clamp circuit is used to achieve zero-voltage switching operation of the power switches. A simple dc-link voltage feedback scheme is applied to the proposed converter. A resonant voltage-doubler rectifier helps the output diodes to achieve zero-current switching operation. The reverse-recovery losses of the output diodes can be eliminated without any additional components. The dc-link capacitor voltage can be reduced, providing reduced voltage stresses of switching devices. Furthermore, power conversion efficiency can be improved by the soft-switching operation of switching devices. The performance of the proposed converter is evaluated on a 160-W (50 V/3.2 A) experimental prototype. The proposed converter complies with International Electrotechnical Commission (IEC) 1000-3-2 Class-D requirements for the light-emitting diode power supply of large-sized liquid crystal displays, maintaining the dc-link capacitor voltage within 400 V under the universal line voltage (90–<formula formulatype="inline"><tex Notation="TeX">$265\ {\rm V}_{{\rm rms}}$</tex></formula>). </para>

Analysis and implementation of a novel soft-switching pulse-width modulation converter

A soft-switching pulse-width modulation (PWM) converter with parallel connection to realise the zero voltage switching (ZVS) and achieve load current sharing is presented. The leakage inductance of the transformer and output capacitances of power switches are adopted to realise the resonance at the transition interval of switches such that the ZVS turn-on can be achieved. The energy stored in the transformer leakage and magnetising inductances can be released to limit the peak voltage stress of switching devices. To reduce the ripple current on the output capacitor and reduce the current stress on the secondary windings of the transformer, the parallel-connected circuit with an interleaved PWM scheme is used at the output side to share the load current and reduce the output ripple current. The operation principles, steady-state analysis and design equations of the proposed converter are provided in detail. Finally, experiments based on a 1 kW (12 V/84 A) prototype are provided to verify the theoretical analysis and the effectiveness of the proposed converter.

Interleaved ZVS Converter With Ripple-Current Cancellation

In this paper, an interleaved soft-switching converter with ripple-current cancellation is presented to achieve zero- voltage-switching (ZVS) turn-on and load current sharing. In order to achieve ZVS turn-on, an active snubber is connected in parallel with the primary winding of the transformer. The energy stored in the transformer leakage inductance and magnetizing inductance can be recovered so that the peak voltage stress of switching devices is limited. The resonance at the transition interval is used to realize ZVS turn-on of all switches. In order to achieve three-level pulsewidth-modulation (PWM) scheme, an addition fast-recovery diode is used in the converter. Three-level PWM scheme can reduce the ac ripple current on the output inductor such that the output inductor can be reduced. The current-doubler rectifier is adopted in the secondary side of the transformer to reduce the transformer secondary-winding current and output voltage ripple by canceling the current ripple of two output inductors. The output voltage is controlled at the desired value using the interleaved PWM scheme. These features make the proposed converter suitable for the dc-dc converter with high output current. The operation principles, steady state analysis, and design equations of the proposed converter are provided in detail. Finally, experiments based on a 600-W (12 V/50 A) prototype are provided to verify the effectiveness and feasibility of the proposed converter.

Analysis and Implementation of a ZVS-PWM Converter With Series-Connected Transformers

This brief presents the analysis, design, and implementation of zero-voltage switching (ZVS) active clamp converter with series-connected transformer. A family of isolated ZVS active clamp converters is introduced. The technique of the adopted ZVS commutation will not increase additional voltage stress of switching devices. In the adopted converter with series-connected transformer, each transformer can be operated as an inductor or a transformer. Therefore, no output inductor is needed. To reduce the voltage stress of the switching device in the conventional forward converter, the active clamp technique is used to recycle the energy stored in the transformer leakage back into the input dc source. Finally, experimental results are presented taken from a laboratory prototype with 100-W rated power, input voltage of 155 V, output voltage of 5 V, and operating at 150 kHz.

Soft-Switching Zeta–Flyback Converter With a Buck–Boost Type of Active Clamp

This paper presents the system analysis, design consideration, and implementation of a soft-switching zeta-flyback converter to achieve zero-voltage switching (ZVS). In the proposed converter, the zeta and flyback topologies are adopted in the output side to achieve the following features: to share the power components in the transformer primary side, to achieve the partial magnetizing flux reset, and to share the output power. The buck-boost type of active clamp is connected in parallel with the primary side of the isolation transformer to recycle the energy stored in the leakage inductor of isolated transformer and to limit the peak voltage stress of switching devices due to the transformer leakage inductor when the main switch is turned off. The active clamp circuit can make the switching devices to turn on at ZVS. Experimental results taken from a laboratory prototype rated at 240 W, input voltage of 150 V, output voltage of 12 V, and switching frequency of 150 kHz are presented to demonstrate the converter performance. Based on the experimental results, the circuit efficiency is about 90.5% at rated output power, and the output voltage variation is about 1%.

Analysis of the ZVS two‐switch forward converter with synchronous current doubler rectifier

AbstractA soft switching two‐switch forward converter is presented to achieve zero voltage switching (ZVS) turn‐on of switching devices. In the adopted converter, a buck‐boost type of active clamp is connected in parallel with the primary winding of transformer. The energy stored in the transformer leakage inductance and magnetizing inductance can be recovered so that the peak voltage stress of switching devices is limited. The resonance between the transient interval of two main and auxiliary switches is used to achieve ZVS turn‐on of all switches. The current doubler synchronous rectifier is used in the secondary side of transformer for reducing the root mean square value of output inductor current, transformer secondary winding current and output voltage ripple by cancelling the current ripple of two output inductors. First, the circuit configuration and the principles of operation are analyzed in detail. The steady‐state analysis and design consideration are also presented. Finally, experimental results with a laboratory prototype based on a 380 V input and 12 V/30 A output were provided to verify the effectiveness of the proposed converter. Copyright © 2007 John Wiley &amp; Sons, Ltd.