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Cascaded H-bridge (CHB) multilevel inverters have been conceived as an alternative to reduce total harmonic distortion (THD) in medium-voltage drives. The reduced THD makes them useful for electric vehicle (EV) applications, but the main problem with the CHB is the large amount of isolated power sources required to feed each of the H-bridges. An im...
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... 5 is obtained by plotting (13) as a function of k. As shown in Fig. 5, Aux − 1 does not give power to the load when k = 0.783, k = 0.38, and k < 0.115. Of particular interest is the first value (k = 0.783), because, at this value, the converter works with 23 levels and without the need to feed the Aux − 1 bridges. As a result, these H-bridges behave like series active power filters because they do not ...
Context 2
... shown in Fig. 9, when the number of levels is smaller than 9, the power is completely transferred to load through the Aux- bridges. The minimum power transferred through the HFL is when k = 0.783, which is the same value of k for P Aux−1 = 0 shown in Fig. 5. As a consequence, when Aux − 1 works as a series active power filter, the toroidal transformer and the HFL are minimized, and the percentage of full power transferred through this device is only 1.9%. The rest of the load power comes from the MAIN ...
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The development of Science and Technology has spurred the development of distributed generation, as well as the application of new renewable energy sources. DG connected to the grid can alter the power flow on the grid, reduce voltage loss and grid capacity loss; and also enhance the incident and reliability of grid power supply. When the number of...
Citations
... Reference [80] applies CHB to an induction motor-based electric vehicle propulsion system, which enabled the system to exhibit high dynamic performance and almost eliminate torque ripple. Reference [81] uses an improved CHB called asymmetric CHB (ACHB) as shown in Fig. 10c. Under the condition that the electric vehicle is powered by a single DC source, the auxiliary H-bridge obtains different DC voltages through a small high-frequency link (HFL). ...
Multilevel inverters (MIs) are widely used in voltage source inverter applications due to their advantages of high-quality output voltage waveform, low power loss and low voltage stress. Compared with multiple DC source MI (MDCS-MI), single DC source MI (SDCS-MI) needs one DC source. This makes SDCS-MI more simplified and avoid voltage unevenness among multiple sources, which are advantageous in renewable energy (RE) applications. In order to understand SDCS-MI, this paper classifies and compares existing SDCS-MIs according to classical topologies based on isolated and non-isolated construction, summarizes the advantages and limitations of each type of topologies, and briefly introduces various control strategies of SDCS-MI. Finally, this paper discusses the SDCS-MI in RE systems. In addition, the development trend of SDCS-MI is also analyzed in this paper.
... Recently, MLIs have been the subject of many studies in low-voltage hybrid or allelectric heavy-duty (trucks, buses) and passenger EVs [19,34,45,[59][60][61][62][63][64]. ...
... Asymmetrical CHB MLI that uses different-sized H-bridges and requires a less isolated DC source than symmetrical CHB was analyzed for application in small EVs [59]. A proposed solution consists of the main H-bridge working at the fundamental frequency and additional small H-bridges operating as series active power filters. ...
All electric vehicles are the only way to decarbonize transport quickly and substantially. Although multilevel inverters have already been used in some transportation modes, they are rarely used in road transportation, especially in light-duty passenger BEVs. With the transition to a high 800-V DC link to extend the driving range and enable extreme fast charging, the possibility of using multilevel inverters in commercial light-duty passenger BEVs becomes feasible. Higher efficiency, higher power density, better waveform quality, lower switching frequency, the possibility of using low-rated switches, and inherent fault tolerance are known advantages of multilevel inverters that make them an efficient option for replacing 2-level inverters in high DC link passenger BEVs. This paper discusses high DC link voltage benefits in light-duty passenger BEVs, presents the state-of-the-art of different conventional multilevel inverter topologies used in BEVs, and compares them with conventional 2-level inverters from different aspects and limitations. Based on commercial upper-class passengers’ BEV data and a review of multilevel inverters on the market, future trends and possible research areas are identified.
... Several cascaded multilevel converters ensure electrical isolation from high-frequency transformers (HFT) with less weight and volume than conventional line-frequency transformers operating at 50/60 Hz [10]. Among them, the cascaded H-bridges use HFT as part of a high-frequency link (HFL), making possible the use of only one dc power source instead of one isolated source per H-bridge [11], [12]. Based on this concept, ac-dc-ac multilevel converters have also been proposed in the literature [13], [14], [15]. ...
... The high-frequency link (HFL) proposed here feeds the dclink of the converter H. As can be seen in Fig. 2(a), the circuit of the HFL is formed by an H-bridge that can be built with MOS-FETs or IGBTs, that generates a high-frequency square-wave voltage (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) to feed a small toroidal ferrite transformer with secondary winding connected to a rectifier bridge with fast recovery diodes, that generates a dc voltage to supply the dc-link of the converter H. ...
... The block GEN − v * l generates the load reference voltage (v * l ) from a reference amplitude (V * l ) and angle (θ l ). The bidirectional H-bridge of the HFL does not require a specific control for its operation, just needing to generate a high-frequency square waveform of voltage (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) in the primary winding of the high-frequency transformer. As the input of the HFL is connected directly to the dc link of the converter a whose voltage is controlled, the dc voltage at the output of the HFL, supplied through the unidirectional H-bridge, is determined by the transformation ratio of the high-frequency transformer [11]. ...
This paper investigates a single-phase ac-dc-ac multilevel converter formed by a three-leg module (converter
$a$
) series connected to an H-bridge (converter
$H$
) at the load side of the system to achieve higher and multilevel output voltage. The proposed solution has two dc-links that are connected through a high-frequency link (HFL) formed by an inverter H-bridge, a small toroidal transformer, and a unidirectional rectifier H-bridge. The use of the HFL permits optimizing the SV-PWM strategy by employing vector redundancies that minimize the switching frequency of the devices. Besides, the control system is simplified compared to the conventional solution with floating capacitors. The proposed system is appropriate for uninterrupted power supply and unified power quality conditioner applications. System equations, dc-link voltage specifications, power distribution analysis, and a space vector PWM are discussed. The proposed control strategy ensures suitable load voltage with constant amplitude and fundamental frequency, guaranteeing a high grid power factor and maintaining controlled dc-link voltages. Compared with the conventional solutions, the proposed topology has a lower dc-link voltage rating, lower harmonic content, and lower switching losses in the converters
$a$
and
$H$
. Experimental results are presented to validate the developed studies.
... require high-quality voltages at terminals to improve [2], [3], [4], wind generator systems [5], electric vehicles [6], [7], ship propulsion [8], and wireless power transfer [9], [10] applications. ...
Multi-level inverters produce low order harmonics in over-modulation region, which can be eliminated by generating polygonal space vector structure. A variable speed induction motor drive to generate 24-stepped voltage waveform throughout modulation range is proposed in this article. An open-end winding configuration induction motor (OEIM) is fed with primary and secondary inverter from both the ends of OEIM and generates a 24-stepped phase voltage. The proposed scheme also produces 96-stepped phase voltage waveform at extreme modulation index with highly suppressed higher order harmonics and excellent quality phase voltage. The motor terminal sees a 24-stepped waveform at all speeds, devoid of low order harmonics up to
$19^{th}$
order. The scheme does not require vector timing calculation due to availability of highly dense 24-sided polygonal structure. Primary and secondary inverters are derived by cascading flying capacitor and CHB cells. Experimental verifications are performed on in-house developed laboratory prototype. Motor phase voltage and phase current waveforms during steady state and transient conditions justifies performance of the proposed scheme. Dynamic performance and floating capacitors voltage balancing method are verified by experimental results.
... Generally, cascaded H-bridge (CHB) multilevel inverter gives better result with less %THD, but requires many DC sources and generates only positive voltage levels. In Pereda and Dixon (2012), an asymmetrical CHB MLI is proposed which uses only one DC source and can be applied in Electric vehicle applications. A crisscross MLI with reduced number of components is proposed in Khosroshahi (2014), which has very advanced features. ...
In this paper, an asymmetric source configuration of Multilevel Inverter (MLI) topology has been proposed. It consists of eight unidirectional switches, two bidirectional switches and four isolated DC sources. By considering 1:5 and 1:4 source configurations, the inverter produces 25-level and 21-level outputs respectively with the same switching action. For producing negative voltage levels, there is no requirement of separate backend H-bridge and inherently produces both positive and negative voltage levels. The main advantage of this topology is that in every state, only four switches are in ON mode and else are in OFF state. It also gives less per unit Total Standing Voltage (TSV) and thereby cost requirement of semiconductor devices can become decreases. For generating gate pulses, the simple Nearest Level Control (NLC) has been used by considering the round function. This technique is basically a fundamental switching frequency technique thereby switching losses are greatly reduces as compared with high switching frequency Pulse Width Modulation (PWM) techniques and it is particularly suitable for large number of levels. With this control technique, there is no inrush current has been developed at the input of DC sources. Finally, with step change in Modulation Index (MI) values the proposed topology with two different source configurations have been validated through MATLAB/Simulink platform.
... Low switch stress, scalability, and generating output voltage with reduced harmonics are all advantages of the CHB topology. In [3], a trinary asymmetrical CHB is configured with a DC source. However, it requires high-frequency transformers. ...
In this paper, a 17-level asymmetric Cascaded H-Bridge (CHB) converter with integrating a Level Doubling Circuit (LDC) is presented. A fundamental switching frequency modulation technique is adapted for the generation of required gate pulse to the proposed topology. The suggested architecture necessitates the use of two asymmetric DC sources with a 1:3 magnitude ratio, ten switches, and a self-balanced capacitor. By cascading the H Bridges, the suggested architecture can create a greater number of voltage levels. The proposed Asymmetric CHB inverter generates N levels with the help of log3(N+12) DC sources, 2+4log3(N+12) switches, and a capacitor. In comparison to the existing topologies presented in literature, the proposed Asymmetric CHB requires fewer switches and DC sources for an N number of voltage levels. The proposed topology is simulated in the MATLAB/SIMULINK. A Level Shift - PWM (LS-PWM) method is implemented by considering the carrier frequency is equal to 50Hz. Further, the simulation results are verified experimentally using dSPACE 1104 by use of a prototype model made in a laboratory. In the output voltage waveform, the Total Hormonic Distortion (THD) is less than 5%.
... for even sources Su (2004) There exists various applications for the MLIs, out of these some of them are as follows: the authors described in Babaei et al. (2014b), Rech and Pinheiro (2007) and Khomfoi and Aimsaard (2009) Gupta and Jain (2013) Gupta and Jain (2012b) 10 6 (2016) are employed. Manjrekar and Lipo (1998) and Kiran Kumar and Sivakumar (2015) are widely in motor driven applications and Pereda and Dixon (2012) and Araujo-Vargas et al. (2014) are proposed MLIs for aviation and marine propeller transportation and the representation is shown in Fig. 15. The control scheme and power electronic switches design and various quantitative details are tabulated in Table 8. ...
... The authors of Pereda and Dixon (2012), suggested that the EV application should have a single, high frequency (HFL) connection and this work pioneered the use of a low power transformer with modulation adjustment. The recommended switching method reduces the HFL's size from 20% to less than 2% of the machine's total power. ...
In general, multilevel inverters (MLIs) are regarded as advanced power conversion systems required for medium-voltage and high-power applications. The purpose of this article is to provide an overview of recently investigated MLI topologies classified into various categories based on the transformer requirement such as the transformer less (TL-MLI) and transformer-based (T-MLI) with single and multi-source topologies of symmetric, asymmetric, hybrid and single DC sources for renewable energy applications. For the previous few decades, multiple new variants of each group have been developed. The design and functioning of each topology, as well as each group, are examined in this study. T-MLI topologies of H-bridge, three-leg inverter-based, and other T-MLI configurations are discussed from a configuration standpoint. Each topology's state-of-the-art of both MLI configurations and problems are treated separately. Furthermore, the disadvantages and benefits of each topology have been thoroughly addressed. Finally, a comparison of existing topologies is conducted to determine the optimal topology based on several performance characteristics and the cost evaluation has been presented. This article provides a comprehensive overview of recently developed multilevel inverters and provides a solution for developing the MLIs for future research on renewable energy applications.
... Multilevel Inverters (MLIs) are state-of-the-art power electronic converters that have taken the place of traditional inverters in many applications, such as renewable energy systems, grid integration systems, mechanical drives, electric vehicles, and FACTS [1][2][3][4]. MLIs are mostly preferred in different applications because of their efficient power generating features with lower switching losses and low voltage stress across switches [5]. MLIs are mainly classified as Neutral Point Clamped (NPC), Flying Capacitor (FC), and Cascaded H-bridge Inverter [6][7][8][9]. ...
Multilevel inverters are increasingly being employed for industrial applications, such as speed control of motors and grid integration of distributed generation systems. The focus is on developing topologies that utilize fewer lower-rating switches and power sources while working efficiently and reliably. This work pertains to developing a three-phase multilevel inverter that employs switching capacitors and a single DC power supply that produces a nine-stage, three-phase voltage output. A recently proposed powerful meta-heuristic technique called symbiotic organism search (SOS) has been applied to identify the optimum switching angles for Selective Harmonic Elimination (SHE) from the output voltage waveform. A thorough converter analysis has also been done in the MATLAB/SIMULINK environment and is validated with the real-time hardware-in-the-loop (HIL) experiment results.
... Also, some of these dc-sources need to be bidirectional, because they regenerate energy for lower modulation index [21]. Some solutions are proposed to reduce the number of isolated sources, such as by using floating capacitors in some cells [22], [23], high frequency link (HFL) [20], [24], [25], and hybrid solutions that involve these two approaches [26]. Once, in asymmetric cascade inverters, most of the power is supplied by the higher dc-source voltage, HFL has been proposed as a solution to supply auxiliary sources, as it provides isolation with reduced weight and volume when compared to line frequency transformers. ...
... In [24] and [25], two solutions composed of HFL and cascaded H-bridge operating with a single dc-source have been proposed. These topologies are three-phase inverters with three asymmetric cells per phase (9 : 3 : 1 ratio). ...
... It is worth noting that in [24] the HFL manages less than 20% of the load power and the converter produces 27 voltage levels. The ACHB proposed in [25], uses a bidirectional HFL system and to reduce power processing in HFT, operates with reduced modulation index with 23-levels, managing less than 2%. ...
... Conventional UPQCs also employ this equipment [2], [3]. To overcome these drawbacks, a common solution in machinedrive systems is to employ a DC-DC converter isolated with a high-frequency transformer to connect the DC-links of different cells [12], [13]. This technique has already been proposed for active filter systems using bidirectional and unidirectional DC-DC converters [14]- [20]. ...
