Total harmonic distortion <span style="font-size: 9pt; font-family: 'Times New Roman', serif;" lang="EN-US">(THD) is</span><span style="font-size: 10.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;" lang="EN-US"> a key index used to measure the quality of output waveforms in multilevel inverters. In this paper </span><span style="font-size: 9pt; font-family: 'Times New Roman', serif;" lang="EN-US">the THD is investigated and compared between two modulation methods; selective harmonic elimination and nearest level control, for 13-level transistor clamped H-bridge (TCHB) inverter. The selected TCHB topology employs a reduced number of DC sources and switches compared with other conventional multilevel inverters, which helps to reduce the size and cost of the inverter. The performance of both modulation methods has been validated through simulations using MATLAB/Simulink. The results show that for selective harmonic elimination, the 13-level output exists for a narrow range of modulation index,</span> <em>M</em> (0.687≤M≤0.694),<span style="font-size: 9pt; font-family: 'Times New Roman', serif;" lang="EN-US">while for nearest level control method, the 13-level output exists for a wider range of</span> <em>M</em> (M≥0.917), <span style="font-size: 9pt; font-family: 'Times New Roman', serif;" lang="EN-US">which means the 13-level output exists for different ranges of </span><!--[if gte msEquation 12]><m:oMath><i style='mso-bidi-font-style:normal'><span lang=EN-US style='font-size:9.0pt; font-family:"Cambria Math",serif;mso-fareast-font-family:"Times New Roman"; mso-bidi-font-family:"Times New Roman";color:black;mso-ansi-language:EN-US; mso-fareast-language:EN-US;mso-bidi-language:AR-SA'><m:r>M</m:r></span></i></m:oMath><![endif]--><!--[if !msEquation]--><!--[endif]--><span style="font-size: 9pt; font-family: 'Times New Roman', serif;" lang="EN-US"> for both methods. The THD obtained from both methods fulfills the IEEE Std 519-2014 standard of harmonics. Nearest level control method is conceptually simple and produces better THD results compared with selective harmonic elimination method.</span><span style="font-size: 9pt; font-family: 'Times New Roman', serif;" lang="EN-US">distortion (THD) is</span><span style="font-size: 10.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;" lang="EN-US"> a key index used to measure the quality of output waveforms in multilevel inverters. In this paper </span><span style="font-size: 9pt; font-family: 'Times New Roman', serif;" lang="EN-US">the THD is investigated and compared between two modulation methods; selective harmonic elimination and nearest level control, for 13-level transistor clamped H-bridge (TCHB) inverter. The selected TCHB topology employs a reduced number of DC sources and switches compared with other conventional multilevel inverters, which helps to reduce the size and cost of the inverter. The performance of both modulation methods has been validated through simulations using MATLAB/Simulink. The results show that for selective harmonic elimination, the 13-level output exists for a narrow range of modulation index, </span><!--[if gte msEquation 12]><m:oMath><i style='mso-bidi-font-style:normal'><span lang=EN-US style='font-size:9.0pt; font-family:"Cambria Math",serif;mso-fareast-font-family:"Times New Roman"; mso-bidi-font-family:"Times New Roman";color:black;mso-ansi-language:EN-US; mso-fareast-language:EN-US;mso-bidi-language:AR-SA'><m:r>M</m:r></span></i></m:oMath><![endif]--><!--[if !msEquation]--><!--[endif]--><span style="font-size: 9pt; font-family: 'Times New Roman', serif;" lang="EN-US"> </span><span style="font-size: 9pt; font-family: 'Times New Roman', serif;" lang="MS">(</span><!--[if gte msEquation 12]><m:oMath><i style='mso-bidi-font-style:normal'><span lang=MS style='font-size:9.0pt; font-family:"Cambria Math",serif;mso-fareast-font-family:"Times New Roman"; mso-bidi-font-family:"Times New Roman";color:black;mso-ansi-language:MS; mso-fareast-language:EN-US;mso-bidi-language:AR-SA'><m:r>0.687≤</m:r><m:r>M</m:r><m:r>≤0.694</m:r></span></i></m:oMath><![endif]--><!--[if !msEquation]--><!--[endif]--><span style="font-size: 9pt; font-family: 'Times New Roman', serif;" lang="MS">)</span><span style="font-size: 9pt; font-family: 'Times New Roman', serif;" lang="EN-US">, while for nearest level control method, the 13-level output exists for a wider range of </span><!--[if gte msEquation 12]><m:oMath><i style='mso-bidi-font-style:normal'><span lang=EN-US style='font-size:9.0pt; font-family:"Cambria Math",serif;mso-fareast-font-family:"Times New Roman"; mso-bidi-font-family:"Times New Roman";color:black;mso-ansi-language:EN-US; mso-fareast-language:EN-US;mso-bidi-language:AR-SA'><m:r>M</m:r></span></i></m:oMath><![endif]--><!--[if !msEquation]--><!--[endif]--><span style="font-size: 9pt; font-family: 'Times New Roman', serif;" lang="EN-US"> (</span><!--[if gte msEquation 12]><m:oMath><i style='mso-bidi-font-style:normal'><span lang=EN-US style='font-size:9.0pt; font-family:"Cambria Math",serif;mso-fareast-font-family:"Times New Roman"; mso-bidi-font-family:"Times New Roman";color:black;mso-ansi-language:EN-US; mso-fareast-language:EN-US;mso-bidi-language:AR-SA'><m:r>M</m:r><m:r>≥0.917</m:r></span></i></m:oMath><![endif]--><!--[if !msEquation]--><!--[endif]--><span style="font-size: 9pt; font-family: 'Times New Roman', serif;" lang="EN-US">), which means the 13-level output exists for different ranges of </span><!--[if gte msEquation 12]><m:oMath><i style='mso-bidi-font-style:normal'><span lang=EN-US style='font-size:9.0pt; font-family:"Cambria Math",serif;mso-fareast-font-family:"Times New Roman"; mso-bidi-font-family:"Times New Roman";color:black;mso-ansi-language:EN-US; mso-fareast-language:EN-US;mso-bidi-language:AR-SA'><m:r>M</m:r></span></i></m:oMath><![endif]--><!--[if !msEquation]--><!--[endif]--><span style="font-size: 9pt; font-family: 'Times New Roman', serif;" lang="EN-US"> for both methods. The THD obtained from both methods fulfills the IEEE Std 519-2014 standard of harmonics. Nearest level control method is conceptually simple and produces better THD results compared with selective harmonic elimination method</span>

Multilevel inverters are gaining special interest among researchers and in the industry due to their widespread applications and numerous merits. Obtaining high quality, more reliable output while using a reduced number of electronic components is the main purpose of most of the research conducted in this area of study. The purpose of this study is to apply the nearest level control (NLC) method to a 13-level transistor-clamped H-bridge (TCHB) inverter with unequal DC voltage supplies. The NLC method operates at the fundamental frequency, thus reducing switching losses, and can reduce the harmonic content significantly. The adopted multilevel inverter consists of two TCHB cells supplied with two asymmetrical DC input sources with a voltage ratio of 1:2. This structure reduces the number of electronic components, and the asymmetry in the DC input voltages results in a higher number of levels. The adopted topology and its proposed control method were simulated in Matlab/Simulink, and the simulation results were verified through experiments using an Altera field-programmable gate array (FPGA) board. The results showed that the topology and its control method are efficient in obtaining a high-quality output with an improved total harmonic distortion (THD).

No abstract

This paper proposes a nearest level control method based modulation scheme for a 9-level symmetrical Transistor Clamped H-bridge (TCHB) inverter. The topology has gained increasing research focus due to its advantages in obtaining high quality output while using a reduced number of electronic components. The device count for obtaining a 9-level output voltage is it uses 10 active switches as compared to the 16 being used in a conventional 9-level cascaded H-Bridge (CHB) inverter. The significant contribution of the research is the development of the NLC modulation technique that operates at the fundamental frequency, thus reducing switching losses, and able to reduce harmonic content significantly. The reduced harmonic content can lessen the power quality problem. The NLC modulation scheme, shows that the overall THD is reduced without the need for filtration. The 50 values of harmonic content will be count that follows the IEEE Standard 519. MATLAB/Simulink based simulations and experimental results obtained from the laboratory prototype of a single-phase TCHB inverter feeding a R load validate the theoretical analyses and effectiveness of the proposed modulation scheme.

No abstract