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A Modified Charge Balancing Scheme for Cascaded H-Bridge Multilevel Inverter
Nithin Raj,Jagadanand G,Saly George 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.6
Cascaded H-bridge multilevel inverters are currently used because it enables the integration of various sources, such as batteries, ultracapacitors, photovoltaic array and fuel cells in a single system. Conventional modulation schemes for multilevel inverters have concentrated mainly on the generation of a low harmonic output voltage, which results in less effective utilization of connected sources. Less effective utilization leads to a difference in the charging/discharging of sources, causing unsteady voltages over a long period of operation and a reduction in the lifetime of the sources. Hence, a charge balance control scheme has to be incorporated along with the modulation scheme to overcome these issues. In this paper, a new approach for charge balancing in symmetric cascaded H-bridge multilevel inverter that enables almost 100% charge balancing of sources is presented. The proposed method achieves charge balancing without any additional stages or complex circuit or considerable computational requirement. The validity of the proposed method is verified through simulation and experiments.
Nair Deepthi S,Jagadanand G.,George Saly 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.5
Torque estimation for Direct Torque Controlled BLDC motor drive using Kalman Filter and Extended Kalman Filter are described in this paper. In conventional direct torque control method, the torque estimation is done based on the position information, which in turn requires position sensors for accurate estimation. In this paper, torque is directly estimated using Kalman fi lter and Extended Kalman Filter algorithms without the aid of any feedback information, and a comparison is made between the two. Both the algorithms are perceptive to follow the actual torque; the error between the actual and reference is used for the selection of appropriate voltage vector for inverter switching. The refl ection of load changes in the control algorithm is also a part of the interest in this work. The potential of Extended Kalman Filter to follow exactly the changes in the load torque is utilized here and Extended Kalman Filter based sensorless drive is proposed for the torque estimation in Direct Torque Controlled BLDC motor. The performance parameters, viz. computational eff ort, torque ripple reduction are found to be superior with the Extended Kalman Filter algorithm, which is validated.
A Modified Charge Balancing Scheme for Cascaded H-Bridge Multilevel Inverter
Raj, Nithin,G, Jagadanand,George, Saly The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.6
Cascaded H-bridge multilevel inverters are currently used because it enables the integration of various sources, such as batteries, ultracapacitors, photovoltaic array and fuel cells in a single system. Conventional modulation schemes for multilevel inverters have concentrated mainly on the generation of a low harmonic output voltage, which results in less effective utilization of connected sources. Less effective utilization leads to a difference in the charging/discharging of sources, causing unsteady voltages over a long period of operation and a reduction in the lifetime of the sources. Hence, a charge balance control scheme has to be incorporated along with the modulation scheme to overcome these issues. In this paper, a new approach for charge balancing in symmetric cascaded H-bridge multilevel inverter that enables almost 100% charge balancing of sources is presented. The proposed method achieves charge balancing without any additional stages or complex circuit or considerable computational requirement. The validity of the proposed method is verified through simulation and experiments.
K.J., Pratheesh,G., Jagadanand,Ramchand, Rijil The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.2
The cascaded H Bridge (CHB) multilevel inverter (MLI) is popular among the classical MLI topologies due to its modularity and reliability. Although space vector modulation (SVM) is the most suitable modulation scheme for MLIs, it has not been used widely in industry due to the higher complexity involved in its implementation. In this paper, a simple and novel generalized SVM algorithm is proposed, which has both reduced time and space complexity. The proposed SVM involves the generalization of both the duty cycle calculation and switching sequence generation for any n-level inverter. In order to generate the gate pulses for an inverter, a generalized switch matrix (SM) for the CHB inverter is also introduced, which further simplifies the algorithm. The algorithm is tested and verified for three-phase, three-level and five-level CHB inverters in simulations and hardware implementation. A comparison of the proposed method with existing SVM schemes shows the superiority of the proposed scheme.
Pratheesh K. J.,Jagadanand G.,Rijil Ramchand 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.2
The cascaded H Bridge (CHB) multilevel inverter (MLI) is popular among the classical MLI topologies due to its modularity and reliability. Although space vector modulation (SVM) is the most suitable modulation scheme for MLIs, it has not been used widely in industry due to the higher complexity involved in its implementation. In this paper, a simple and novel generalized SVM algorithm is proposed, which has both reduced time and space complexity. The proposed SVM involves the generalization of both the duty cycle calculation and switching sequence generation for any n-level inverter. In order to generate the gate pulses for an inverter, a generalized switch matrix (SM) for the CHB inverter is also introduced, which further simplifies the algorithm. The algorithm is tested and verified for three-phase, three-level and five-level CHB inverters in simulations and hardware implementation. A comparison of the proposed method with existing SVM schemes shows the superiority of the proposed scheme.