A Transformerless AC-AC Converter with Improved Power Quality Employed to Step-Down Power Frequency at Output
Variable voltage and frequency are required to govern the torque-speed characteristics of many industrial drive systems. Traditionally, this is achieved with a power converting system implemented with multistage converters. This technology is based on rectifying AC power into DC and then DC into AC...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-01-01
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| Series: | Energies |
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| Online Access: | https://www.mdpi.com/1996-1073/15/2/667 |
| _version_ | 1797494279547912192 |
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| author | Naveed Ashraf Ghulam Abbas Nasim Ullah Ahmad Aziz Al-Ahmadi Abdul Rehman Yasin Ahmed Bilal Awan Mohsin Jamil |
| author_facet | Naveed Ashraf Ghulam Abbas Nasim Ullah Ahmad Aziz Al-Ahmadi Abdul Rehman Yasin Ahmed Bilal Awan Mohsin Jamil |
| author_sort | Naveed Ashraf |
| collection | DOAJ |
| description | Variable voltage and frequency are required to govern the torque-speed characteristics of many industrial drive systems. Traditionally, this is achieved with a power converting system implemented with multistage converters. This technology is based on rectifying AC power into DC and then DC into AC with an inverter circuit. The power quality concerns of both conversion stages are tackled by selecting high switching frequency PWM control and harmonics mitigation filters. Also, using a bulky DC-link capacitor is one of the big sources of low system reliability, so this approach increases the conversion losses, circuit, and control complications. The frequency step-down conversion is very attractive with direct AC-AC converters as it has a simple control and circuit structure, but these converters face poor power quality challenges once the output frequency is decreased with respect to an input. In these converters, the total harmonic distortion (THD) of the output voltage becomes very poor once the output frequency is reduced. The problem of high THD of the output is addressed in the power converting circuits implemented with line frequency multi-winding transformers. The required number of output winding and switching devices (diodes and thyristors) increases once the value of the output frequency is decreased. This will increase the overall volume, cost, and losses. The use of a bulky and costly line frequency transformer may be eliminated if AC voltage controllers have non-inverted and inverted voltage buck capabilities, such existing topologies either have complex control schemes or require a large number of operating devices. Therefore, in this research article, a new transformerless frequency step-down converter employing fewer devices is proposed. This approach is realized with a high-frequency controlled rectifier for the required voltage stabilization and a low-frequency inverter bridge for frequency control. Its validation is supported by the results attained from Simulink and practical-based prototypes. |
| first_indexed | 2024-03-10T01:32:05Z |
| format | Article |
| id | doaj.art-e3723d806cc64341bc4231b1bcda1bf8 |
| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-03-10T01:32:05Z |
| publishDate | 2022-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj.art-e3723d806cc64341bc4231b1bcda1bf82023-11-23T13:40:12ZengMDPI AGEnergies1996-10732022-01-0115266710.3390/en15020667A Transformerless AC-AC Converter with Improved Power Quality Employed to Step-Down Power Frequency at OutputNaveed Ashraf0Ghulam Abbas1Nasim Ullah2Ahmad Aziz Al-Ahmadi3Abdul Rehman Yasin4Ahmed Bilal Awan5Mohsin Jamil6Department of Electrical Engineering, The University of Lahore, Lahore 54000, PakistanDepartment of Electrical Engineering, The University of Lahore, Lahore 54000, PakistanDepartment of Electrical Engineering, College of Engineering, Taif University, Taif 21944, Saudi ArabiaDepartment of Electrical Engineering, College of Engineering, Taif University, Taif 21944, Saudi ArabiaDepartment of Electrical Engineering, The University of Lahore, Lahore 54000, PakistanDepartment of Electrical and Computer Engineering, College of Engineering and Information Technology, Ajman University, Ajman 346, United Arab EmiratesDepartment of Electrical and Computer Engineering, Faculty of Engineering and Applied Science, Memorial University of Newfoundland, St. John’s, NL A1B 3X5, CanadaVariable voltage and frequency are required to govern the torque-speed characteristics of many industrial drive systems. Traditionally, this is achieved with a power converting system implemented with multistage converters. This technology is based on rectifying AC power into DC and then DC into AC with an inverter circuit. The power quality concerns of both conversion stages are tackled by selecting high switching frequency PWM control and harmonics mitigation filters. Also, using a bulky DC-link capacitor is one of the big sources of low system reliability, so this approach increases the conversion losses, circuit, and control complications. The frequency step-down conversion is very attractive with direct AC-AC converters as it has a simple control and circuit structure, but these converters face poor power quality challenges once the output frequency is decreased with respect to an input. In these converters, the total harmonic distortion (THD) of the output voltage becomes very poor once the output frequency is reduced. The problem of high THD of the output is addressed in the power converting circuits implemented with line frequency multi-winding transformers. The required number of output winding and switching devices (diodes and thyristors) increases once the value of the output frequency is decreased. This will increase the overall volume, cost, and losses. The use of a bulky and costly line frequency transformer may be eliminated if AC voltage controllers have non-inverted and inverted voltage buck capabilities, such existing topologies either have complex control schemes or require a large number of operating devices. Therefore, in this research article, a new transformerless frequency step-down converter employing fewer devices is proposed. This approach is realized with a high-frequency controlled rectifier for the required voltage stabilization and a low-frequency inverter bridge for frequency control. Its validation is supported by the results attained from Simulink and practical-based prototypes.https://www.mdpi.com/1996-1073/15/2/667DC-link capacitordiodes and thyristorsmultistage convertersmulti-winding transformertotal harmonic distortionvariable voltage and frequency |
| spellingShingle | Naveed Ashraf Ghulam Abbas Nasim Ullah Ahmad Aziz Al-Ahmadi Abdul Rehman Yasin Ahmed Bilal Awan Mohsin Jamil A Transformerless AC-AC Converter with Improved Power Quality Employed to Step-Down Power Frequency at Output Energies DC-link capacitor diodes and thyristors multistage converters multi-winding transformer total harmonic distortion variable voltage and frequency |
| title | A Transformerless AC-AC Converter with Improved Power Quality Employed to Step-Down Power Frequency at Output |
| title_full | A Transformerless AC-AC Converter with Improved Power Quality Employed to Step-Down Power Frequency at Output |
| title_fullStr | A Transformerless AC-AC Converter with Improved Power Quality Employed to Step-Down Power Frequency at Output |
| title_full_unstemmed | A Transformerless AC-AC Converter with Improved Power Quality Employed to Step-Down Power Frequency at Output |
| title_short | A Transformerless AC-AC Converter with Improved Power Quality Employed to Step-Down Power Frequency at Output |
| title_sort | transformerless ac ac converter with improved power quality employed to step down power frequency at output |
| topic | DC-link capacitor diodes and thyristors multistage converters multi-winding transformer total harmonic distortion variable voltage and frequency |
| url | https://www.mdpi.com/1996-1073/15/2/667 |
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