Shoot-through Protection Research Articles

Efficient control of three-phase cascaded multilevel Z-Source inverter using SHEPWM technique

This paper presents an enhanced control strategy for three-phase cascaded multilevel Z-source inverters, focusing on the implementation of Selective Harmonic Elimination Pulse Width Modulation (SHEPWM) techniques to improve efficiency. Z-source inverters are gaining prominence in various applications due to their inherent advantages, such as increased voltage boost capability and inherent shoot-through protection. However, achieving optimal control in cascaded multilevel configurations poses challenges that this study seeks to address. The proposed control strategy optimizes the switching patterns of the inverter, thereby enhancing its overall performance. It allows for precise control over the output voltage and reduces harmonic distortion, ensuring the inverter operates efficiently across varying load conditions. The research methodology involves a comprehensive analysis of the proposed technique, including its mathematical modeling and simulation using advanced software tools. Performance metrics such as total harmonic distortion, efficiency, and transient response are evaluated to quantify the improvements achieved. The results obtained demonstrate the efficiency of the proposed control strategy. This method significantly reduces harmonic distortion in the output voltage, leading to improved power quality. Furthermore, the efficiency of the inverter is enhanced, making it suitable for applications demanding high-performance power conversion.

A Single-Input Multiple-Output Unity Power Factor Rectifier

The increasing consumer electronics, most of which are natively dc loads, demand efficient power conversion from input ac grid to dc loads. Good power quality and unity power factor (UPF) for maintaining a stable grid can be achieved using power factor correction (PFC) circuits. This article proposes a family of single-input multiple-output (SIMO) rectifiers, which can provide one dc output higher and multiple dc outputs lower than the peak voltage of the ac input. Compared to separate conventional rectifiers at every point-of-load, each with a boost-based PFC circuit followed by a buck converter, the proposed topology requires a less number of switches and has inherent shoot-through protection. In this article, the operation of an N-output (N-switch) rectifier is explained, and its general large-signal and small-signal models are developed. It is further illustrated using a single-input dual-output (SIDO) rectifier. Of the two dc outputs, one dc output voltage is higher, and one is lower than the peak voltage of the ac input. The small-signal model and the control scheme to enforce output voltage regulation and UPF operation are discussed. Experimental results are provided to validate the proposed topology and the control scheme.

A Minimum-Phase Dual Output Hybrid Converter for Standalone Hybrid AC/DC Supply Systems

A minimum-phase dual output hybrid converter for standalone hybrid ac/dc supply systems is proposed in this article. Due to its circuit arrangement, the converter eliminates the right half-plane zero from the control-to-dc output voltage transfer function (i.e., making the system minimum-phase) and gives simultaneous ac and dc outputs using single-stage power conversion. Due to the minimum-phase behavior, the converter is capable of operating at a high load current while maintaining closed-loop stability. Further, it enables simpler controller design and faster dynamic response. As it has two inductors, one at the main input voltage terminals and another at the output dc voltage terminals, it gives continuous input/output currents. Also, it gives step-down/step-up dc output voltages along with the step-down ac output voltage based on the duty ratio. It also has inherent shoot-through protection capability, which results in reliable power conversion on the occurrence of misgating of the switches caused by electromagnetic interference. A hybrid pulsewidth modulation scheme is developed to achieve simultaneous ac and dc outputs. Detailed mathematical modeling is carried out to demonstrate the properties of the converter, and its experimental validation is done through a laboratory prototype. Moreover, at different loading conditions, efficiencies of the converter are measured for varying dc load (having constant ac load) and varying ac load (having constant dc load), to show its effectiveness.

Shoot-through protection for an inverter consisting of the next-generation IGBTs with gate impedance reduction

Attention has been paid to the next-generation IGBT toward CMOS compatible wafer processes, which can be driven by a 5-V logic level due to its low threshold gate voltage. This low threshold voltage makes the so-called shoot-through fault severer. Even though the switching speed of the IGBT is intentionally reduced, the shoot-through fault can happen. This paper presents shoot-through protection for an inverter consisting of the next-generation IGBTs with gate impedance reduction. Theoretical analysis reveals the criterion of the gate impedance with taking parasitic parameters of the inverter into account.

Three‐phase quasi‐Z source inverters with regulated multiple AC outputs for microgrid applications and three‐phase residential load

In this study, two 3- φ quasi-Z source inverters (qZSIs) with multiple ac outputs are proposed. The proposed topologies are developed from qZSI to obtain parallel mode and series mode 3- φ multi-output inverters. In parallel mode, the topology yields n -number of parallel ac outputs with different voltages and currents for different load conditions. For series mode, topology yields n -number of series ac outputs with same voltages and same load currents. Unlike voltage source derived multi-output inverters, the proposed inverters have all inherent properties of qZSI, like shoot-through protection and both buck–boost operations. For generating switching signals in these inverters, sinusoidal pulse width modulation with constant frequency shoot-through scheme is used. The proposed topologies fulfil more than one load demand at a time without any extra adaptor or regulator. The proposed inverters can be used for simultaneous multiple dc/ac power conversion for three-phase microgrid applications and three-phase residential loads. In this work, the proposed topologies with closed-loop control have been implemented for two inverter units, which is capable of supplying two ac outputs simultaneously. The mathematical modelling of the proposed topologies is carried out for performance analysis. The experimental results of 240 W lab prototypes have been presented to validate the proposed three-phase multi-output qZSIs.

A High Step-Down Buck Converter With Self-Driven Synchronous Rectifier

In this article, a new single-switch buck converter (without considering the synchronous rectifier) with extended duty cycle and continuous output current is proposed. The presented converter employs a self-driven synchronous rectifier with gate energy recovery, which leads to efficiency improvement and simplicity of the converter and the gate drive circuit. The extended duty cycle results in lower current stress of the high-side MOSFET and reduced voltage stress across the synchronous rectifier. Furthermore, the reverse recovery losses of synchronous rectifier are dramatically decreased due to the applied coupled inductors. The introduced converter also provides shoot-through protection and load protection when the high-side MOSFET remains on . In order to clamp the drain–source voltage spikes of the main switch and recover the leakage inductance energy, a lossless snubber circuit is added, which reduces the turn- off drain–source voltage and consequently decreases the turn- off switching losses of the main MOSFET . Moreover, the main switch turns on under zero current switching (ZCS), which results in efficiency improvement. A 150-W prototype of the proposed converter is implemented to verify the theoretical analysis and confirm its efficiency improvement and advantages.

Hybrid Buck–Boost Multioutput Quasi-Z-Source Converter With Dual DC and Single AC Outputs

This article presents two hybrid multioutput buck-boost quasi-Z-source converters (q-ZSCs) capable of giving two dc and one ac outputs simultaneously from a single dc input. One dc and the ac outputs of the proposed multioutput q-ZSCs have both buck and boost capabilities and the other dc output has the property of boosting the input voltage, thereby capable of giving a wide range of voltage gain both for dc and ac outputs. The rationale behind proposing two variants of the hybrid multioutput q-ZSCs is to have more flexibility on voltage gains as per the load requirements. The proposed converters are derived from the quasi-Z-source concept and hence inherit all the properties of q-ZSI, which realize buck/boost, single-stage inversion, and power conditioning with improved reliability along with inherent shoot-through protection capability. All the three outputs of the proposed converters can be independently controlled making them suitable for various applications. The proposed converters can be utilized for various modern multioutput dc-dc and dc-ac power conversion applications, such as renewables and the uninterrupted power supplies. Detailed steady-state operation, loss/efficiency analysis of the proposed converter, and discussion on the hybrid pulsewidth modulation are presented in this article. In order to bring out the advantages of the proposed multioutput converter, a detailed comparative analysis among the proposed and other closely related existing multioutput converters is carried out in this article. A 310-W prototype is developed to verify the performance of the proposed multioutput buck-boost q-ZSC.

Interleaved Current-Fed Switched Inverter

Current-fed switched inverter (CFSI) is a high-gain inverter topology suitable for applications which have limited input dc source voltage, e.g., roof-top solar applications. A very high step-up ratio between ac output and dc input along with inherent shoot-through protection makes it suitable for low-power stand-alone inverter applications. In this article, a novel interleaved topology for CFSI (ICFSI) is proposed to augment its power rating. A pulsewidth modulation (PWM) scheme is also proposed to drive the interleaved topology. Various modes of operation of ICFSI, along with the steady-state model and dynamic analysis, with the proposed PWM scheme, are reported. ICFSI, with the PWM scheme, results in a 33% increase in maximum ac gain as compared to CFSI. In this article, the small-signal model of ICFSI is also derived and verified. An analysis comparing the losses in CFSI and ICFSI is carried out. It is observed that interleaved operation improves the efficiency by 4% at 600 W. The proposed topology and analysis are verified with the experimental results obtained from a 600-W laboratory-developed prototype.

Control Approach to Enhance the Performance of a Current-Fed Switched Inverter

Current-fed switched inverter (CFSI), a derivative of Z-source inverter, has the advantages of lower component count, single-stage conversion, high gain, and inherent shootthrough protection. But due to the limitation of modulation index, CFSI is forced to operate at higher dc-link voltage. As a result, voltage stress across the switches and capacitors increases. To mitigate this problem, a new pulsewidth modulation (PWM) technique is proposed. With the proposed scheme, CFSI can be operated at a lower dc-link voltage by increasing the modulation index. But operating at lower dc-link voltage increases peakto-peak ripple in the inductor current and leads to condition of early discontinuous conduction mode. Therefore, this paper also implemented a variable duty cycle (VDC) scheme, which reduces the peak-to-peak ripple in the input inductor current and increases the continuous conduction mode (CCM) operating range of CFSI. The proposed PWM scheme along with VDC scheme is validated for CFSI, which helps to: 1) reduce the voltage stress form 280 to 180 V; 2) reduce the input current ripple from 53.33% to 15.15%; 3) enlarge CCM range from 56% to 82%; and 4) improve the efficiency by 3.5%.

A Modified PWM Scheme to Improve Performance of a Single-Phase Active-Front-End Impedance Source Inverter

Impedance source inverters (ISIs) are gaining attention due to features such as single-stage conversion, buck-boost capability, and inherent shoot-through protection. To maintain the required ac output voltage, typically ISIs are operated at a higher dc-link voltage due to constrained modulation index. This also increases voltage stress across capacitors and switches of the converter. This voltage stress is approximately double compared to that of voltage source inverter with preboost stage (Boost-VSI). To mitigate this problem, a new pulsewidth modulation (PWM) scheme for the active-front-end based ISIs (AFE-ISIs) is proposed. The proposed scheme enables the ISIs to produce high ac gain with lower voltage stress across the capacitor and switches. In other words, the proposed scheme blends the advantages of Boost-VSI into ISIs. With the new PWM scheme, there are also reductions in output voltage total harmonic distortion, switching frequency ripple in the inductor current, and power loss in the converter. A prototype of the current-fed switched inverter, an AFE-ISI, is designed, and the proposed PWM scheme is implemented. Experimental results obtained are in accordance with the proposed theory and show that the voltage stress has reduced from 325 V to 203 V for an ac output of 110 V.

Investigation of a PV fed Improved Smart Home EV Battery Charging System using Multi Output Hybrid Converter

Power converters used in the existing smart home electric vehicle (EV) battery charging systems are capable of feeding only dc power. Whereas, this paper proposes the usage of hybrid converters in such systems as they are used for supplying power to both ac and dc loads simultaneously. Among various hybrid converter topologies, boost derived hybrid converter (BDHC) and quadratic boost derived hybrid converter (QBDHC) are analyzed in this paper. A photovoltaic (PV) array fed smart home system using BDHC and QBDHC is proposed to provide both dc power and ac power simultaneously and their performances were compared in this paper. The interfacing of multiple outputs is accomplished using time division multiplexing of power generated from PV array. In the proposed system, the hybrid converter is designed by replacing single switch of conventional boost converter by voltage source inverter (VSI). It has higher reliability in terms of power density and has inherent shoot-through protection during inverter operation. It is best suited for home applications which require support for both ac and dc loads. The system is designed, modeled and simulated using PSIM software and a laboratory prototype is developed and tested. Resemblance between the simulated and experimental results validates the efficaciousness of the proposed system.

Hybrid Converter to Supply DC and AC Loads Using Tapped Boost Topology

Advancements in power electronic systems has brought forth the modernization of residential power systems exponentially. The interfacing of AC and DC loads with various kinds of resources of energy has been achieved with the help of modern nanogrid architectures. This paper brings into depiction a Tapped Boost derived hybrid converter that can be used to meet the demands of both AC and DC loads having a solitary DC input. A voltage source inverter (VSI) bridge network is used instead of the single switch of a Tapped Boost converter. The VSI bridge has shoot-through protection in the inverter stage increasing its importance for smart power systems. The Tapped Boost derived converter also borrows the advantages provided by the Tapped Boost converter. The paper covers topics like the operation, steady-state analysis and operating modes of the proposed Tapped Boost-DHC. The output and input characteristics has also been tested and verified through simulatio

Interleaved Hybrid Converter With Simultaneous DC and AC Outputs for DC Microgrid Applications

This paper proposes an interleaved hybrid converter (IHC) with simultaneous dc and ac outputs for dc microgrid applications. The IHC is realized by interleaving two conventional boost converters and replacing the active switch of lower boost converter by an H-bridge voltage source inverter. This arrangement enables the proposed IHC to operate at the condition where the sum of duty ratio ( $\boldsymbol{D}$ ) and modulation index ( $\boldsymbol{M}$ ) can be more than or equal to one, i.e., $ \boldsymbol{D} + \boldsymbol{M} \geq 1$ , unlike the conventional hybrid converters. The proposed IHC is capable of giving dc with high voltage gain and improved ac with reduced harmonic distortion. Due to interleaving nature of the IHC, input current is shared between the power converters and thus enables the use of low current rated switching devices and lower values of inductors. This results in reduced power losses and increased efficiency as compared to the conventional hybrid converters. The IHC also has inherent shoot-through protection capability, better electromagnetic interference immunity, and reliability. A modified unipolar sinusoidal pulse width modulation technique is used to control the power flow of the IHC. Detailed mathematical modeling of the proposed IHC is carried out and its steady-state behavior is validated through experimental results on a 500 W laboratory prototype.

Integrated Dual-Output Converter

This paper presents a family of single-input-multiple-output (SIMO) dc-dc converter topologies, which can provide one step-up and multiple step-down outputs. These topologies are synthesized by replacing the control switch of a boost converter topology with series-connected switches and using the additional switch nodes to generate step-down dc outputs. Compared with separate converters, these topologies utilize a lower number of switches and are more reliable due to their inherent shoot-through protection. Analysis shows that the topologies exhibit similar dynamic behavior as individual buck and boost converters. Hence, the control system methodology is the same as that of separate converters, with each output being precisely regulated. The behavior of these converters has been illustrated in this paper using the integrated dual-output converter (IDOC), which has a step-up and a step-down output. The steady-state characteristics and dynamic behavior of the converter have been studied. An analog closed-loop control system for the converter has been described for regulation of both the outputs. The operating principles have been experimentally validated using a 120-W prototype. Results show that the proposed converter has very good cross-regulation to step load change as well as dynamic reference change in either output. The measured efficiencies of the IDOC prototype are around 90%.

Boost-Derived Hybrid Converter With Simultaneous DC and AC Outputs

This paper proposes a family of hybrid converter topologies which can supply simultaneous dc and ac loads from a single dc input. These topologies are realized by replacing the controlled switch of single-switch boost converters with a voltage-source-inverter bridge network. The resulting hybrid converters require lesser number of switches to provide dc and ac outputs with an increased reliability, resulting from its inherent shoot-through protection in the inverter stage. Such multioutput converters with better power processing density and reliability can be well suited for systems with simultaneous dc and ac loads, e.g., nanogrids in residential applications. The proposed converter, studied in this paper, is called boost-derived hybrid converter (BDHC) as it is obtained from the conventional boost topology. The steady-state behavior of the BDHC has been studied in this paper, and it is compared with conventional designs. A suitable pulse width modulation (PWM) control strategy, based upon unipolar sine-PWM, is described. A DSP-based feedback controller is designed to regulate the dc as well as ac outputs. A 600-W laboratory prototype is used to validate the operation of the converter. The proposed converter is able to supply dc and ac loads at 100 V and 110 V (rms), respectively, from a 48-V dc input. The performance of the converter is demonstrated with inductive and nonlinear loads. The converter exhibits superior cross-regulation properties to dynamic load-change events. The proposed concept has been extended to quadratic boost converters to achieve higher gains.

A Shoot-Through Protection Scheme for Converters Built With SiC JFETs

The SiC JFET is an attractive semiconductor device due to its superior switching performance and high-temperature operating capability. Its shoot-through protection remains a challenge due to the limited practical knowledge existent on this device and due to its inherent normally on nature. Addressing this limitation, this paper presents a novel shoot-through protection scheme in which a bidirectional switch, compounded by a Si insulated-gate bipolar transistor (IGBT) and a relay,is embedded into the dc-link midpoint in order to detect and clear shoot-through faults, taking advantage of the well-known desaturation protection schemes of IGBTs to protect SiC JFETs. This paper describes in detail the proposed protection mechanism and its circuit design, presenting as well the experimental results that verified the effectiveness of the proposed scheme using, first, Si MOSFETs and second, a 10-kW ac–ac converter system using SiC JFETs.

공정 및 공급전압 변화에 강인한 하프브리지 구동 IC의 설계

In this paper, we propose a novel shoot-through protection circuit and pulse generator for half-bridge driver IC. We designed a robust half-bridge driver IC over a variation of processes and power supplies. The proposed circuit is composed a delay circuit using a beta-multiplier reference. The proposed circuit has a lower variation rate of dead time and pulse-width over variation of processes and supply voltages than the conventional circuit. Especially, the proposed circuit has more excellent pulse-width matching of set and reset signals than the conventional circuit. Also, the proposed pulse generator is prevented from fault operations using a logic gate. Dead time and pulse-width of the proposed circuit are typical 250 ns, respectively. The variation ratio is 68%(170 ns) of maximum over variation of processes and supply voltages. The proposed circuit is designed using 1 μm 650 V BCD (Bipolar, CMOS, DMOS) process parameter, and the simulations are carried out using Spectre simulator of Cadence corporation.