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K Gopakumar - One of the best experts on this subject based on the ideXlab platform.

  • a switched capacitive filter based harmonic elimination technique by generating a 30 sided voltage space vector structure for im drive
    IEEE Transactions on Power Electronics, 2020
    Co-Authors: R Rakesh, K Gopakumar, L Umanand, Krishna Raj Ramachandran, Apurv Kumar Yadav, Kouki Matsuse
    Abstract:

    This paper proposes a novel polygonal voltage space vector structure (SVS) having 30 sides, for a star-connected induction motor drive. The SVS eliminates the presence of harmonics up to 25th order from motor phase voltage throughout the entire Modulation range, providing a torque profile devoid of lower order pulsations. Linear Modulation is extended till 99.63% of base speed without exceeding the motor phase voltage rating. Topology consists of a dc-link fed primary inverter and two equal low voltage modular capacitor fed secondary inverters. Here the harmonics generated by the primary inverter is canceled by the secondary inverter which acts as a switched capacitive filter. Detailed description of the SVS generation and timing calculations are provided in this paper. Effectiveness of the proposed scheme is validated using experimental results, inverter loss calculations, and harmonic analysis.

  • an induction motor drive scheme generating twenty four sided voltage space vector structure with Linear Modulation range near to base speed
    European Conference on Power Electronics and Applications, 2017
    Co-Authors: Raj R Krishna, K Gopakumar, Mathews Boby, Mariusz Malinowski, Marek Jasinski
    Abstract:

    In this paper, a drive scheme generating 24-sided polygonal voltage space vector structure using an inverter topology with single DC source is proposed. A 24-sided structure eliminates dominant low order phase voltage harmonics including and up to seventeenth and nineteenth orders throughout the speed range including step operation. The power circuit has a two-level inverter and two low voltage cascaded H-bridge cells fed with capacitors. The Linear Modulation range is extended to 99.42% of the base speed with such a polygonal structure. A reduced PWM switching sequence resulting in minimum pole voltage transitions for the two-level inverter and shifting relatively higher frequency operation to low voltage H-Bridge inverters feature the drive scheme for controlling losses.

  • extending the Linear Modulation range to the full base speed using a single dc link multilevel inverter with capacitor fed h bridges for im drives
    IEEE Transactions on Power Electronics, 2017
    Co-Authors: Arun Rahul S, Sudharshan R Kaarthik, K Gopakumar, Sumit Pramanick, Frede Blaabjerg
    Abstract:

    In this paper, a new space vector pulse width Modulation method to extend the Linear Modulation range of a cascaded five level inverter topology with a single dc supply is presented. Using this method, the inverter can be controlled Linearly and the peak phase fundamental output voltage of the inverter can be increased from 0.577 to 0.637 ${V}_{\text{dc}}$ without increasing the dc bus voltage and without exceeding the induction motor voltage rating. This new technique makes use of cascaded inverter pole voltage redundancy and property of the space vector structure for its operation. Using this, the induction motor drive can be operated till the full speed range (0–50 Hz) with the elimination of lower order harmonics in the phase voltage and phase current. The five-level topology presented in this paper is realized by cascading a two-level inverter and two full bridge modules with floating capacitors. The inverter topology and its operation for extending the Modulation range is analyzed extensively. Simulation and experimental results for both steady-state and dynamic operating conditions are presented in this paper.

  • a 24 sided voltage space vector based im drive with low order harmonic elimination for the full speed range
    IEEE Transactions on Industrial Electronics, 2017
    Co-Authors: Krishna Raj R, K Gopakumar, Mathews Boby, Mariusz Malinowski, Marek Jasinski
    Abstract:

    This paper proposes an inverter topology to generate a 24-sided polygonal voltage space vector structure for variable speed drives using a single dc source. The topology consists of a two-level inverter cascaded with two low-voltage floating capacitor-fed H-bridge cells. The 24-sided structure eliminates harmonics up to and including seventeenth and nineteenth orders from phase voltage output resulting in a smooth torque profile over the entire speed range. This structure also enhances the Linear Modulation range to 99.42% of the base speed. A reduced switching sequence based pulse width Modulation technique achieves minimum pole voltage transitions for the two-level inverter, thereby controlling switching losses. The lower order harmonics are eliminated by switching action of low-voltage H-bridge cells. Experimental results, simulation studies on inverter losses, and harmonic performance validate the effectiveness of proposed drive scheme.

  • a multilevel inverter fed im drive with dodecagonal voltage space vector structure using a single dc source with Linear Modulation range near to base speed
    European Conference on Power Electronics and Applications, 2016
    Co-Authors: Mathews Boby, K Gopakumar, Sumit Pramanick, Arun S Rahul, L Umanand
    Abstract:

    A fifth and seventh order harmonic elimination scheme for IM drive with a multilevel dodecagonal voltage space vector structure using a single DC source is proposed in this work. Single DC source requirement makes four quadrant operation of the drive system simpler compared to the multilevel do-decagonal structures presented in literatures before. The space vector structure consists of six concentric dodecagons, combining the advantages of multilevel operation as well as dodecagonal structure. The topology consists of a three-level flying capacitor (FC) inverter cascaded with a capacitor fed H-bridge (CHB) inverter. The FC inverter operating at high voltage switches in a quasi-square wave mode whereas the CHB inverter operating at a lower voltage switches at high frequency to remove the harmonics generated by the FC inverter. Switching losses are low, both in the FC and CHB inverters. Experiment results for open-loop V/f operation are included in this paper showing the effectiveness of the drive scheme.

B P Mcgrath - One of the best experts on this subject based on the ideXlab platform.

  • an improved three phase variable band hysteresis current regulator
    IEEE Transactions on Power Electronics, 2013
    Co-Authors: D G Holmes, R Davoodnezhad, B P Mcgrath
    Abstract:

    This paper presents an improved variable-band hysteresis current controller for a two-level three-phase voltage source inverter (VSI). The controller takes the average voltages of the phase-leg switched outputs as an approximation to the load back-EMF voltages, and uses these results to vary the hysteresis bands so as to maintain constant phase-leg switching frequencies. The switching frequency control process is then further refined by fine tuning the hysteresis band variations to synchronize the zero crossings of the phase-leg current errors with a fixed reference clock so as to achieve a nearest space vector switching sequence, which further ensures that the switched output spectrum has been optimized. Finally, a technique is proposed to replace the third phase-leg current regulator with a fixed-frequency open-loop pulse-width modulator, where its commanded reference is generated from the average switched output voltages of the other two phase legs. This avoids the hazard of the three independent hysteresis current regulators adversely interacting with each other in a conventional system, resulting from an overconstrained control problem with only two degrees of freedom. Additionally, this approach allows the Linear Modulation range to be increased by adding a common-mode third-harmonic component to the third phase-leg reference command signal.

  • an improved three phase variable band hysteresis current regulator
    International Conference on Performance Engineering, 2011
    Co-Authors: D G Holmes, R Davoodnezhad, B P Mcgrath
    Abstract:

    This paper presents an improved variable band hysteresis current controller for a two level three phase voltage source inverter. The controller takes the average voltages of the phase-leg switched outputs as an approximation to the load back-EMFs, and uses this result to vary the hysteresis bands to maintain constant phase leg switching frequencies. The switching frequency control process is then further refined by fine tuning the hysteresis band variations to synchronise the zero crossings of the phase leg current errors with a fixed reference clock, to ensure nearest space vector switching and hence achieve the best possible harmonic switching performance. Finally, a technique is proposed to replace the third phase leg current regulator with a fixed frequency open loop PWM modulator, where its commanded reference is generated from the average switched output voltage of the other two phases. This avoids the hazard of three independent current regulators in a conventional system adversely interacting as an over constrained control problem, and allows the Linear Modulation range to be increased by adding a common mode third harmonic component to the third phase leg reference command.

  • an improved three phase variable band hysteresis current regulator
    International Conference on Performance Engineering, 2011
    Co-Authors: D G Holmes, R Davoodnezhad, B P Mcgrath
    Abstract:

    This paper presents an improved variable band hysteresis current controller for a two level three phase voltage source inverter. The controller takes the average voltages of the phase-leg switched outputs as an approximation to the load back-EMFs, and uses this result to vary the hysteresis bands to maintain constant phase leg switching frequencies. The switching frequency control process is then further refined by fine tuning the hysteresis band variations to synchronise the zero crossings of the phase leg current errors with a fixed reference clock, to ensure nearest space vector switching and hence achieve the best possible harmonic switching performance. Finally, a technique is proposed to replace the third phase leg current regulator with a fixed frequency open loop PWM modulator, where its commanded reference is generated from the average switched output voltage of the other two phases. This avoids the hazard of three independent current regulators in a conventional system adversely interacting as an over constrained control problem, and allows the Linear Modulation range to be increased by adding a common mode third harmonic component to the third phase leg reference command.

  • reduced pwm harmonic distortion for multilevel inverters operating over a wide Modulation range
    IEEE Transactions on Power Electronics, 2006
    Co-Authors: B P Mcgrath, D G Holmes, Thierry Meynard
    Abstract:

    It is known that the optimal carrier based approach for modulating a multilevel converter is to use a phase disposition (PD) carrier arrangement with a common mode offset added to the reference waveforms to centre the implicitly selected space vectors. However, this strategy does not fully utilize all available voltage levels at lower Modulation depths, with an odd level system only using odd voltage levels and an even level system only using even voltage levels as the Modulation depth varies. Recent work has suggested that this is not the harmonically optimal approach at reduced Modulation depths. This paper shows how up to a 40% reduction in harmonic distortion can be achieved if all available voltage levels are used throughout the Linear Modulation range. The improvement is achieved by adding a simple (1/2) carrier magnitude common mode dc offset in key Modulation regions, which allows the converter to use all available voltage levels. The paper uses analytical spectral decomposition and harmonic flux trajectory analysis to propose a theoretical basis for this improvement, and to determine the precise points at which the (1/2) carrier magnitude offset should be added to achieve the harmonic improvement.

D G Holmes - One of the best experts on this subject based on the ideXlab platform.

  • an improved three phase variable band hysteresis current regulator
    IEEE Transactions on Power Electronics, 2013
    Co-Authors: D G Holmes, R Davoodnezhad, B P Mcgrath
    Abstract:

    This paper presents an improved variable-band hysteresis current controller for a two-level three-phase voltage source inverter (VSI). The controller takes the average voltages of the phase-leg switched outputs as an approximation to the load back-EMF voltages, and uses these results to vary the hysteresis bands so as to maintain constant phase-leg switching frequencies. The switching frequency control process is then further refined by fine tuning the hysteresis band variations to synchronize the zero crossings of the phase-leg current errors with a fixed reference clock so as to achieve a nearest space vector switching sequence, which further ensures that the switched output spectrum has been optimized. Finally, a technique is proposed to replace the third phase-leg current regulator with a fixed-frequency open-loop pulse-width modulator, where its commanded reference is generated from the average switched output voltages of the other two phase legs. This avoids the hazard of the three independent hysteresis current regulators adversely interacting with each other in a conventional system, resulting from an overconstrained control problem with only two degrees of freedom. Additionally, this approach allows the Linear Modulation range to be increased by adding a common-mode third-harmonic component to the third phase-leg reference command signal.

  • an improved three phase variable band hysteresis current regulator
    International Conference on Performance Engineering, 2011
    Co-Authors: D G Holmes, R Davoodnezhad, B P Mcgrath
    Abstract:

    This paper presents an improved variable band hysteresis current controller for a two level three phase voltage source inverter. The controller takes the average voltages of the phase-leg switched outputs as an approximation to the load back-EMFs, and uses this result to vary the hysteresis bands to maintain constant phase leg switching frequencies. The switching frequency control process is then further refined by fine tuning the hysteresis band variations to synchronise the zero crossings of the phase leg current errors with a fixed reference clock, to ensure nearest space vector switching and hence achieve the best possible harmonic switching performance. Finally, a technique is proposed to replace the third phase leg current regulator with a fixed frequency open loop PWM modulator, where its commanded reference is generated from the average switched output voltage of the other two phases. This avoids the hazard of three independent current regulators in a conventional system adversely interacting as an over constrained control problem, and allows the Linear Modulation range to be increased by adding a common mode third harmonic component to the third phase leg reference command.

  • an improved three phase variable band hysteresis current regulator
    International Conference on Performance Engineering, 2011
    Co-Authors: D G Holmes, R Davoodnezhad, B P Mcgrath
    Abstract:

    This paper presents an improved variable band hysteresis current controller for a two level three phase voltage source inverter. The controller takes the average voltages of the phase-leg switched outputs as an approximation to the load back-EMFs, and uses this result to vary the hysteresis bands to maintain constant phase leg switching frequencies. The switching frequency control process is then further refined by fine tuning the hysteresis band variations to synchronise the zero crossings of the phase leg current errors with a fixed reference clock, to ensure nearest space vector switching and hence achieve the best possible harmonic switching performance. Finally, a technique is proposed to replace the third phase leg current regulator with a fixed frequency open loop PWM modulator, where its commanded reference is generated from the average switched output voltage of the other two phases. This avoids the hazard of three independent current regulators in a conventional system adversely interacting as an over constrained control problem, and allows the Linear Modulation range to be increased by adding a common mode third harmonic component to the third phase leg reference command.

  • reduced pwm harmonic distortion for multilevel inverters operating over a wide Modulation range
    IEEE Transactions on Power Electronics, 2006
    Co-Authors: B P Mcgrath, D G Holmes, Thierry Meynard
    Abstract:

    It is known that the optimal carrier based approach for modulating a multilevel converter is to use a phase disposition (PD) carrier arrangement with a common mode offset added to the reference waveforms to centre the implicitly selected space vectors. However, this strategy does not fully utilize all available voltage levels at lower Modulation depths, with an odd level system only using odd voltage levels and an even level system only using even voltage levels as the Modulation depth varies. Recent work has suggested that this is not the harmonically optimal approach at reduced Modulation depths. This paper shows how up to a 40% reduction in harmonic distortion can be achieved if all available voltage levels are used throughout the Linear Modulation range. The improvement is achieved by adding a simple (1/2) carrier magnitude common mode dc offset in key Modulation regions, which allows the converter to use all available voltage levels. The paper uses analytical spectral decomposition and harmonic flux trajectory analysis to propose a theoretical basis for this improvement, and to determine the precise points at which the (1/2) carrier magnitude offset should be added to achieve the harmonic improvement.

Frede Blaabjerg - One of the best experts on this subject based on the ideXlab platform.

  • pwm common mode reference generation for maximizing the Linear Modulation region of chb converters in islanded microgrids
    IEEE Transactions on Industrial Electronics, 2018
    Co-Authors: Jacob Lamb, Behrooz Mirafzal, Frede Blaabjerg
    Abstract:

    Microgrid-interactive converters are increasingly expected to provide auxiliary services, particularly during islanded microgrid operation. Unbalanced, non-sinusoidal pulse width Modulation (PWM) references may be required when converters provide auxiliary services, such as negative-sequence compensation. Since PWM references cannot exceed dc-bus voltage defined limits without causing overModulation, the maximum positive-sequence voltage producible by microgrid-interactive converters may be diminished unless reference waveforms are adjusted. In this paper, a technique for maximizing the Linear Modulation region by injecting a common mode component into PWM references is proposed for microgrid-interactive cascaded H-bridge (CHB) converters. The technique presented can be implemented in real-time without lookup tables, is controller independent, is compatible with any carrier-based PWM method, enabling its use for symmetric and asymmetric CHB, and enables continued operation after internal fault events when utilized with fault tolerant PWM schemes. Experimental data verify the common mode injection technique.

  • extending the Linear Modulation range to the full base speed using a single dc link multilevel inverter with capacitor fed h bridges for im drives
    IEEE Transactions on Power Electronics, 2017
    Co-Authors: Arun Rahul S, Sudharshan R Kaarthik, K Gopakumar, Sumit Pramanick, Frede Blaabjerg
    Abstract:

    In this paper, a new space vector pulse width Modulation method to extend the Linear Modulation range of a cascaded five level inverter topology with a single dc supply is presented. Using this method, the inverter can be controlled Linearly and the peak phase fundamental output voltage of the inverter can be increased from 0.577 to 0.637 ${V}_{\text{dc}}$ without increasing the dc bus voltage and without exceeding the induction motor voltage rating. This new technique makes use of cascaded inverter pole voltage redundancy and property of the space vector structure for its operation. Using this, the induction motor drive can be operated till the full speed range (0–50 Hz) with the elimination of lower order harmonics in the phase voltage and phase current. The five-level topology presented in this paper is realized by cascading a two-level inverter and two full bridge modules with floating capacitors. The inverter topology and its operation for extending the Modulation range is analyzed extensively. Simulation and experimental results for both steady-state and dynamic operating conditions are presented in this paper.

Dushan Boroyevich - One of the best experts on this subject based on the ideXlab platform.

  • fast processing Modulation strategy for the neutral point clamped converter with total elimination of low frequency voltage oscillations in the neutral point
    IEEE Transactions on Industrial Electronics, 2007
    Co-Authors: Josep Pou, Pedro Rodriguez, Vicent Sala, J Zaragoza, Rolando Burgos, Salvador Ceballos, Dushan Boroyevich
    Abstract:

    This paper presents a novel Modulation strategy for a neutral-point-clamped converter. This strategy overcomes one of the main problems of this converter, which is the low-frequency voltage oscillation that appears in the neutral point under some operating conditions. The proposed Modulation strategy can completely remove this oscillation for all the operating points and for any kind of loads, even unbalanced and nonLinear loads. The algorithm is based on a carrier-based pulsewidth Modulation. Nevertheless, it can generate the maximum output-voltage amplitudes that are attainable under Linear Modulation, such as space-vector Modulation. Furthermore, this technique can be implemented with a very simple algorithm and, hence, can be processed very quickly. The only drawback of this strategy is that the switching frequencies of the devices are one third higher than those of standard sinusoidal pulsewidth Modulation. A control loop for balancing the voltages on the dc-link capacitors is also proposed. This balancing strategy is designed, so that it does not further increase the switching frequencies of the devices when it is applied to the converter. The proposed Modulation technique is verified by simulation and experiment.

  • fast processing Modulation strategy for the neutral point clamped converter with total elimination of the low frequency voltage oscillations in the neutral point
    Conference of the Industrial Electronics Society, 2005
    Co-Authors: Josep Pou, Pedro Rodriguez, Vicent Sala, J Zaragoza, Rolando Burgos, Dushan Boroyevich
    Abstract:

    This paper presents a novel Modulation strategy for the neutral-point-clamped converter. This strategy overcomes one of the main problems of this converter, which is the low-frequency voltage oscillation that appears in the neutral point under some operating conditions. The proposed Modulation strategy can completely remove this oscillation for all the operating points and for any kind of loads, even unbalanced and nonLinear loads. The algorithm is based on a carrier-based PWM. Nevertheless, it can generate the maximum output voltage amplitudes attainable under Linear Modulation, such as space-vector Modulation. Furthermore, this technique can be implemented with a very simple algorithm, and hence can be processed very quickly. A control loop for balancing the voltages on the DC-link capacitors is also proposed. This balancing strategy is designed so that it does not increase the switching frequencies of the devices when it is applied to the converter. The proposed Modulation technique is verified by simulation and experiment