A Virtual Negative Resistor Based Common Mode Current Resonance Suppression Method for Three-Level Grid-Tied Inverter with Discontinuous PWM
The output LC filter of a photovoltaic (PV) string three-level grid-tied inverter that connects the filter capacitor neutral point to dc-link capacitor neutral point can reduce the common-mode (CM) current injected to the grid by letting the CM current circulate within the inverter. However, the int...
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| Format: | Article |
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MDPI AG
2020-04-01
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| Series: | Energies |
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| Online Access: | https://www.mdpi.com/1996-1073/13/7/1595 |
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| author | Qiyu Li Hongwei Zhou Jiansong Zhang Shengdun Zhao Jingfeng Lu |
| author_facet | Qiyu Li Hongwei Zhou Jiansong Zhang Shengdun Zhao Jingfeng Lu |
| author_sort | Qiyu Li |
| collection | DOAJ |
| description | The output LC filter of a photovoltaic (PV) string three-level grid-tied inverter that connects the filter capacitor neutral point to dc-link capacitor neutral point can reduce the common-mode (CM) current injected to the grid by letting the CM current circulate within the inverter. However, the internal CM current may resonate because of the existence of the resonant frequency of the internal CM LC circuit. Compared with the traditional continuous pulse-width modulation (CPWM), the resonance can be worse if discontinuous pulse-width modulation (DPWM) is applied, for the zero sequence quantity of DPWM contains more harmonics than that of CPWM. In this paper, a virtual negative resistor based common mode current resonance suppression method for a three-level grid-tied inverter is proposed to overcome the CM current resonance problem in DPWM application. Different positions of the virtual negative resistor in the equivalent CM circuit with different feedback variables are analyzed theoretically. The virtual negative resistor connected in series with the inductor in the equivalent CM circuit is selected to damp the CM current resonance for simplification and damping performance. Different from the implementation in CPWM where a pair of small voltage vectors exist and are used to adjust the CM voltage directly, the proposed method for DPWM application is implemented indirectly by adding the CM adjustment quantity to differential-mode (DM) control quantity with appropriate coefficients. Depending on the sector of DM control quantity in the <inline-formula> <math display="inline"> <semantics> <mrow> <mrow> <mi mathvariant="sans-serif">α</mi> <mi mathvariant="sans-serif">β</mi> </mrow> </mrow> </semantics> </math> </inline-formula> reference frame, the coefficients are calculated using one of three specific voltage vectors. Experimental results are given to demonstrate the effectiveness of theoretical analyses and the proposed method. |
| first_indexed | 2024-03-10T20:45:36Z |
| format | Article |
| id | doaj.art-16e564eb3c3d4e3fbcc923c0745355e4 |
| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-03-10T20:45:36Z |
| publishDate | 2020-04-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj.art-16e564eb3c3d4e3fbcc923c0745355e42023-11-19T20:20:52ZengMDPI AGEnergies1996-10732020-04-01137159510.3390/en13071595A Virtual Negative Resistor Based Common Mode Current Resonance Suppression Method for Three-Level Grid-Tied Inverter with Discontinuous PWMQiyu Li0Hongwei Zhou1Jiansong Zhang2Shengdun Zhao3Jingfeng Lu4School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaTBEA Xi’an Electric Technology Co., Ltd., Xi’an 710119, ChinaSchool of Electrical Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaSchool of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaTBEA Xi’an Electric Technology Co., Ltd., Xi’an 710119, ChinaThe output LC filter of a photovoltaic (PV) string three-level grid-tied inverter that connects the filter capacitor neutral point to dc-link capacitor neutral point can reduce the common-mode (CM) current injected to the grid by letting the CM current circulate within the inverter. However, the internal CM current may resonate because of the existence of the resonant frequency of the internal CM LC circuit. Compared with the traditional continuous pulse-width modulation (CPWM), the resonance can be worse if discontinuous pulse-width modulation (DPWM) is applied, for the zero sequence quantity of DPWM contains more harmonics than that of CPWM. In this paper, a virtual negative resistor based common mode current resonance suppression method for a three-level grid-tied inverter is proposed to overcome the CM current resonance problem in DPWM application. Different positions of the virtual negative resistor in the equivalent CM circuit with different feedback variables are analyzed theoretically. The virtual negative resistor connected in series with the inductor in the equivalent CM circuit is selected to damp the CM current resonance for simplification and damping performance. Different from the implementation in CPWM where a pair of small voltage vectors exist and are used to adjust the CM voltage directly, the proposed method for DPWM application is implemented indirectly by adding the CM adjustment quantity to differential-mode (DM) control quantity with appropriate coefficients. Depending on the sector of DM control quantity in the <inline-formula> <math display="inline"> <semantics> <mrow> <mrow> <mi mathvariant="sans-serif">α</mi> <mi mathvariant="sans-serif">β</mi> </mrow> </mrow> </semantics> </math> </inline-formula> reference frame, the coefficients are calculated using one of three specific voltage vectors. Experimental results are given to demonstrate the effectiveness of theoretical analyses and the proposed method.https://www.mdpi.com/1996-1073/13/7/1595CPWMDPWMvirtual negative resistorcommon mode current resonance suppression |
| spellingShingle | Qiyu Li Hongwei Zhou Jiansong Zhang Shengdun Zhao Jingfeng Lu A Virtual Negative Resistor Based Common Mode Current Resonance Suppression Method for Three-Level Grid-Tied Inverter with Discontinuous PWM Energies CPWM DPWM virtual negative resistor common mode current resonance suppression |
| title | A Virtual Negative Resistor Based Common Mode Current Resonance Suppression Method for Three-Level Grid-Tied Inverter with Discontinuous PWM |
| title_full | A Virtual Negative Resistor Based Common Mode Current Resonance Suppression Method for Three-Level Grid-Tied Inverter with Discontinuous PWM |
| title_fullStr | A Virtual Negative Resistor Based Common Mode Current Resonance Suppression Method for Three-Level Grid-Tied Inverter with Discontinuous PWM |
| title_full_unstemmed | A Virtual Negative Resistor Based Common Mode Current Resonance Suppression Method for Three-Level Grid-Tied Inverter with Discontinuous PWM |
| title_short | A Virtual Negative Resistor Based Common Mode Current Resonance Suppression Method for Three-Level Grid-Tied Inverter with Discontinuous PWM |
| title_sort | virtual negative resistor based common mode current resonance suppression method for three level grid tied inverter with discontinuous pwm |
| topic | CPWM DPWM virtual negative resistor common mode current resonance suppression |
| url | https://www.mdpi.com/1996-1073/13/7/1595 |
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