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

  • A Novel Split Phase Induction Motor Drive without Harmonic Filters and with Linear Voltage Control for the Full Modulation Range
    EPE Association, 2006
    Co-Authors: K K Mohapatra, Gopakumar K
    Abstract:

    A modulation scheme for a split phase (six phase) induction motor is presented in this paper. For a six phase induction motor drive harmonics of the order 6n +/- 1 (n = 1, 3, 5 etc.) will not contribute to the air gap flux and hence these harmonic currents are limited by the stator impedance only. So harmonic filters are needed for the suppression of these (6n +/- 1( n = 1, 3, 5 etc.) high amplitude harmonic currents, when a six phase induction motor is used for variable speed application. In the proposed scheme, a modulation technique to eliminate the 6n +/- 1 (n = 1, 3, 5 etc.) harmonic currents, without the need for harmonic filters, from the stator phases of a six phase induction motor drive is explained. An open-end winding drive configuration with appropriate DC-link voltages, is chosen in such away that a 12-sided polygonal voltage Space phasor combinations are achieved for each 3-phase group, independently. A modulation scheme based on 12-sided polygonal voltage Space Phasors cancel the 6n +/- 1 (n = 1, 3, 5 etc.) harmonic voltages from all the motor phases and hence currents due to these harmonics can not flow in the motor phases of the six phase machine. For the same flux level of operation, nearly 11.5 % increase in modulation range is possible from this proposed drive (while still being in the linear PWM range), which is more than that of a six-step over modulation region in a conventional 3-phase induction motor drive. The proposed drive scheme is experimentally verified, for variable speed application, using a 1.5 kW six-phase induction motor drive

  • A Novel Modulation Scheme for a Six Phase Induction Motor with Open-End Windings
    IEEE, 2002
    Co-Authors: K K Mohapatra, V T Somasekhar, Gopakumar K, Umanand L
    Abstract:

    A modulation scheme for a six phase induction motor is presented in this paper. For a six phase induction motor drive harmonics of the order $6n\pm 1(n=1,3,5\hSpace {5mm} etc.,)$ will not contribute to the air gap flux and hence these harmonic currents are limited by the stator impedance only. So harmonic filters are needed for the suppression of these $6n\pm1(n=1,3,5\hSpace{5mm}etc.,)$ high amplitude harmonic currents, when a six phase induction motor is used for variable speed application. In the proposed scheme, a modulation technique to eliminate the $6n\pm1(n=1,3,5\hSpace{5 mm}etc.,)$ harmonic currents, without the need for harmonic filters, from the stator phases of a six phase induction motor drive is explained. An open-end winding drive configuration with DC link voltages, chosen in such away that a 12-sided polygonal voltage Space phasor combinations are achieved for each 3-phase group, independently. A modulation scheme based on 12-sided polygonal voltage Space Phasors will cancel the $6n\pm1(n=1,3,5\hSpace{5mm}etc.,)$ harmonic voltages from all the motor phases and hence currents due to these harmonics will not flow in the motor phases of the six phase machine. The proposed drive scheme is experimentally verified, for variable speed application, using a 1 HP six phase induction motor drive

  • Split Phase Induction Motor Operation from PWM Voltage Source Inverter
    IEEE, 1991
    Co-Authors: Gopakumar K, V. T. Ranganathan
    Abstract:

    Split-phase AC motors, with 30 deg. separation between the two groups of stator windings are used in conjunction with current source inverters, in order to eliminate sixth harmonic torque pulsations. The present paper examines the operation of split- phase induction motors from pulse width modulated (PWM) voltage source inverters. Splitting the phase windings leads to reduced voltage ratings for the inverter switches. The inverters are operated with Space phasor based PWM. I t is well known that with this technique, a three phase inverter can give a maximum peak fundamental of 0.577 $V_D_C$ for the motor phase voltage (with a circular trajectory for the voltage Space phasor), as against 0.5 $V_D_C$ with sine triangle modulation. In the case of split- phase machines operated from two inverters, it can be shown that the equivalent 3 phase maximum peak fundamental can be 0.622 $V_D_C$ with the DC bus voltage being half the value $V_D_C$ for the conventional 3 phase configuration. If the DC bus voltage is given as light boost (in order to keep the resultant voltage Space phasor magnitude, the same for the split- phase configuration as compared to the 3 phase configuration), and made (0.5 $V_D_C$ )/cos15, the maximum peak fundamental motor voltage obtainable is 0.643$V_D_C$, which is more than what is obtainable by resorting to six-step operation in the three phase motor. Further, as compared to seven positions for the Space phasor of voltage in three phase machines, forty eight different Space phasor locations are possible in the split-phase machine. The boundary of the Space Phasors is now a 12 sided polygon. By switching between locations within the polygon, it is possible to generate reduced Space phasor amplitudes with lower harmonics than in the three phas

V. T. Ranganathan - One of the best experts on this subject based on the ideXlab platform.

  • pwm inverter switching strategy for a dual two level inverter fed open end winding induction motor drive with a switched neutral
    IEE Proceedings - Electric Power Applications, 2002
    Co-Authors: V T Somasekhar, Andre Pittet, K Gopakumar, V. T. Ranganathan
    Abstract:

    A dual two-level inverter fed open-end winding induction motor drive is proposed in this paper. A total of 64 voltage Space phasor combinations are possible in this scheme since each inverter produces eight voltage Space Phasors. The scheme produces voltage Space phasor locations similar to that of a three-level inverter except that in a three-level inverter the series-connected DC link capacitors carry the load current, which results in undesirable fluctuating voltage Space Phasors. Also, a three-level inverter requires a bulky DC link capacitor. In the proposed scheme the DC link capacitor carries only the ripple current and hence the voltage Space phasor fluctuations are absent. A PWM switching strategy aimed at suppressing the zero sequence currents is proposed, using auxiliary switch-assisted neutral generation.

  • a novel pwm inverter switching strategy for a dual two level inverter fed open end winding induction motor drive
    International Conference on Power Electronics and Drive Systems, 2001
    Co-Authors: V T Somasekhar, Andre Pittet, K Gopakumar, V. T. Ranganathan
    Abstract:

    A dual two-level inverter fed open-end winding induction motor drive is proposed in this paper. A total of 64 voltage Space phasor combinations are possible in this scheme as each inverter produces eight voltage Space Phasors. The proposed scheme produces voltage Space phasor locations similar to that of a 3-level inverter. In a 3-level inverter the series connected DC link capacitors carry the load current. This results in a fluctuating voltage Space Phasors, which is undesirable. Also, a 3-level inverter requires a bulky DC link capacitor. In the proposed scheme the DC link capacitor carries only the ripple current and hence the voltage Space phasor fluctuations are absent. A novel PWM switching strategy aimed to suppress the zero sequence currents is also proposed in this paper, without the need for harmonic filters and isolation transformers.

  • Split Phase Induction Motor Operation from PWM Voltage Source Inverter
    IEEE, 1991
    Co-Authors: Gopakumar K, V. T. Ranganathan
    Abstract:

    Split-phase AC motors, with 30 deg. separation between the two groups of stator windings are used in conjunction with current source inverters, in order to eliminate sixth harmonic torque pulsations. The present paper examines the operation of split- phase induction motors from pulse width modulated (PWM) voltage source inverters. Splitting the phase windings leads to reduced voltage ratings for the inverter switches. The inverters are operated with Space phasor based PWM. I t is well known that with this technique, a three phase inverter can give a maximum peak fundamental of 0.577 $V_D_C$ for the motor phase voltage (with a circular trajectory for the voltage Space phasor), as against 0.5 $V_D_C$ with sine triangle modulation. In the case of split- phase machines operated from two inverters, it can be shown that the equivalent 3 phase maximum peak fundamental can be 0.622 $V_D_C$ with the DC bus voltage being half the value $V_D_C$ for the conventional 3 phase configuration. If the DC bus voltage is given as light boost (in order to keep the resultant voltage Space phasor magnitude, the same for the split- phase configuration as compared to the 3 phase configuration), and made (0.5 $V_D_C$ )/cos15, the maximum peak fundamental motor voltage obtainable is 0.643$V_D_C$, which is more than what is obtainable by resorting to six-step operation in the three phase motor. Further, as compared to seven positions for the Space phasor of voltage in three phase machines, forty eight different Space phasor locations are possible in the split-phase machine. The boundary of the Space Phasors is now a 12 sided polygon. By switching between locations within the polygon, it is possible to generate reduced Space phasor amplitudes with lower harmonics than in the three phas

V T Somasekhar - One of the best experts on this subject based on the ideXlab platform.

  • A Novel PWM Inverter Switching Strategy for a Dual Two-level Inverter Fed Open- end Winding Induction Motor Drive
    2014
    Co-Authors: V T Somasekhar, Kgopakumar Sm Ieee, Andre Pittet Smieee, V. Ranganathan Sm T. Ieee
    Abstract:

    Absrracl--A dual two-level inverter fed open-end winding induction motor drive is proposed in this paper. A total of 64 voltage Space phasor combinations are possible in this scheme as each inverter produces eight voltage Space Phasors. The proposed scheme produces voltage Space phasor locations similar to that of a 3-level inverter. In a 3-level Inverter the series connected DC link capacitors carry the load current. This results in a fluctuating voltage Space Phasors, which is undesirable. Also, a 3-level inverter requires a bulky DC link capacitor. In the proposed scheme the DC link capacitor carries only the ripple current and hence the voltage Space phasor fluctuations are absent. A novel PWM switching strategy aimed to suppress the zero sequence currents is also proposed in thls paper, without the need for harmonle filters and Isolation transformers. Index Term- 4)pen- end winding Induction motor, PWM technique I

  • a Space vector based pwm method using only the instantaneous amplitudes of reference phase voltages for three level inverters
    Epe Journal, 2003
    Co-Authors: K Gopakumar, V T Somasekhar, K K Mohapatra, L Umamand
    Abstract:

    This paper presents a Space vector based PWM method for the 3-level inverter. The three level inverter Space Phasors are located in 19 locations forming 24 sectors. The instantaneous reference Space phasor is generated by switching between the three vectors forming the sector in which the tip of the reference vector lies. The proposed PWM method does not require the sector identification and look up tables to select the appropriate vectors. The inverter leg switching times are directly obtained from the instantaneous reference phase voltage amplitudes and the inverter switching vectors are automatically generated . The inverter leg switching times and the appropriate vectors are obtained using an algorithm, which does not involve computations like square root or coordinate transformations. The proposed method is implemented on a 1hp induction motor drive and the experiment results are presented.

  • pwm inverter switching strategy for a dual two level inverter fed open end winding induction motor drive with a switched neutral
    IEE Proceedings - Electric Power Applications, 2002
    Co-Authors: V T Somasekhar, Andre Pittet, K Gopakumar, V. T. Ranganathan
    Abstract:

    A dual two-level inverter fed open-end winding induction motor drive is proposed in this paper. A total of 64 voltage Space phasor combinations are possible in this scheme since each inverter produces eight voltage Space Phasors. The scheme produces voltage Space phasor locations similar to that of a three-level inverter except that in a three-level inverter the series-connected DC link capacitors carry the load current, which results in undesirable fluctuating voltage Space Phasors. Also, a three-level inverter requires a bulky DC link capacitor. In the proposed scheme the DC link capacitor carries only the ripple current and hence the voltage Space phasor fluctuations are absent. A PWM switching strategy aimed at suppressing the zero sequence currents is proposed, using auxiliary switch-assisted neutral generation.

  • Multi Level Voltage Space Phasor Generation for an Open-End Winding Induction Motor Drive Using a Dual Inverter Scheme with Asymmetrical DC-Link Voltages
    EPE Journal, 2002
    Co-Authors: V T Somasekhar, K Gopakumar, E.g. Shivakumar, Andre Pittet
    Abstract:

    AbstractAn open-end winding induction motor drive fed from two inverters with different DC-link voltages is proposed in this paper. A total of 64 voltage Space phasor combinations are possible in this scheme, as each inverter is capable of producing 8-voltage Space Phasors independently of the other. The proposed scheme produces 37 voltage Space phasor locations while a 3-level inverter produces only 18 voltage Space phasor locations. In the proposed scheme, the neutral connection of the induction motor is removed (open-end winding) and is fed from both the ends. Two 2-level inverters with isolated DC-link voltages of 2/3 Vdc and 1/3 Vdc are used for driving the motor, where Vdc denotes the DC-link voltage of an equivalent conventional (single-inverter) scheme. A combination of two 2-level inverters with 2/3 Vdc and 1/3 Vdc DC-link voltages produces a total of 64 voltage Space phasor combinations in 37 Space phasor locations. The voltage Space phasor locations can be associated with three regions accordin...

  • A Novel Modulation Scheme for a Six Phase Induction Motor with Open-End Windings
    IEEE, 2002
    Co-Authors: K K Mohapatra, V T Somasekhar, Gopakumar K, Umanand L
    Abstract:

    A modulation scheme for a six phase induction motor is presented in this paper. For a six phase induction motor drive harmonics of the order $6n\pm 1(n=1,3,5\hSpace {5mm} etc.,)$ will not contribute to the air gap flux and hence these harmonic currents are limited by the stator impedance only. So harmonic filters are needed for the suppression of these $6n\pm1(n=1,3,5\hSpace{5mm}etc.,)$ high amplitude harmonic currents, when a six phase induction motor is used for variable speed application. In the proposed scheme, a modulation technique to eliminate the $6n\pm1(n=1,3,5\hSpace{5 mm}etc.,)$ harmonic currents, without the need for harmonic filters, from the stator phases of a six phase induction motor drive is explained. An open-end winding drive configuration with DC link voltages, chosen in such away that a 12-sided polygonal voltage Space phasor combinations are achieved for each 3-phase group, independently. A modulation scheme based on 12-sided polygonal voltage Space Phasors will cancel the $6n\pm1(n=1,3,5\hSpace{5mm}etc.,)$ harmonic voltages from all the motor phases and hence currents due to these harmonics will not flow in the motor phases of the six phase machine. The proposed drive scheme is experimentally verified, for variable speed application, using a 1 HP six phase induction motor drive

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

  • A Novel Split Phase Induction Motor Drive without Harmonic Filters and with Linear Voltage Control for the Full Modulation Range
    EPE Association, 2006
    Co-Authors: K K Mohapatra, Gopakumar K
    Abstract:

    A modulation scheme for a split phase (six phase) induction motor is presented in this paper. For a six phase induction motor drive harmonics of the order 6n +/- 1 (n = 1, 3, 5 etc.) will not contribute to the air gap flux and hence these harmonic currents are limited by the stator impedance only. So harmonic filters are needed for the suppression of these (6n +/- 1( n = 1, 3, 5 etc.) high amplitude harmonic currents, when a six phase induction motor is used for variable speed application. In the proposed scheme, a modulation technique to eliminate the 6n +/- 1 (n = 1, 3, 5 etc.) harmonic currents, without the need for harmonic filters, from the stator phases of a six phase induction motor drive is explained. An open-end winding drive configuration with appropriate DC-link voltages, is chosen in such away that a 12-sided polygonal voltage Space phasor combinations are achieved for each 3-phase group, independently. A modulation scheme based on 12-sided polygonal voltage Space Phasors cancel the 6n +/- 1 (n = 1, 3, 5 etc.) harmonic voltages from all the motor phases and hence currents due to these harmonics can not flow in the motor phases of the six phase machine. For the same flux level of operation, nearly 11.5 % increase in modulation range is possible from this proposed drive (while still being in the linear PWM range), which is more than that of a six-step over modulation region in a conventional 3-phase induction motor drive. The proposed drive scheme is experimentally verified, for variable speed application, using a 1.5 kW six-phase induction motor drive

  • a Space vector based pwm method using only the instantaneous amplitudes of reference phase voltages for three level inverters
    Epe Journal, 2003
    Co-Authors: K Gopakumar, V T Somasekhar, K K Mohapatra, L Umamand
    Abstract:

    This paper presents a Space vector based PWM method for the 3-level inverter. The three level inverter Space Phasors are located in 19 locations forming 24 sectors. The instantaneous reference Space phasor is generated by switching between the three vectors forming the sector in which the tip of the reference vector lies. The proposed PWM method does not require the sector identification and look up tables to select the appropriate vectors. The inverter leg switching times are directly obtained from the instantaneous reference phase voltage amplitudes and the inverter switching vectors are automatically generated . The inverter leg switching times and the appropriate vectors are obtained using an algorithm, which does not involve computations like square root or coordinate transformations. The proposed method is implemented on a 1hp induction motor drive and the experiment results are presented.

  • A Novel Modulation Scheme for a Six Phase Induction Motor with Open-End Windings
    IEEE, 2002
    Co-Authors: K K Mohapatra, V T Somasekhar, Gopakumar K, Umanand L
    Abstract:

    A modulation scheme for a six phase induction motor is presented in this paper. For a six phase induction motor drive harmonics of the order $6n\pm 1(n=1,3,5\hSpace {5mm} etc.,)$ will not contribute to the air gap flux and hence these harmonic currents are limited by the stator impedance only. So harmonic filters are needed for the suppression of these $6n\pm1(n=1,3,5\hSpace{5mm}etc.,)$ high amplitude harmonic currents, when a six phase induction motor is used for variable speed application. In the proposed scheme, a modulation technique to eliminate the $6n\pm1(n=1,3,5\hSpace{5 mm}etc.,)$ harmonic currents, without the need for harmonic filters, from the stator phases of a six phase induction motor drive is explained. An open-end winding drive configuration with DC link voltages, chosen in such away that a 12-sided polygonal voltage Space phasor combinations are achieved for each 3-phase group, independently. A modulation scheme based on 12-sided polygonal voltage Space Phasors will cancel the $6n\pm1(n=1,3,5\hSpace{5mm}etc.,)$ harmonic voltages from all the motor phases and hence currents due to these harmonics will not flow in the motor phases of the six phase machine. The proposed drive scheme is experimentally verified, for variable speed application, using a 1 HP six phase induction motor drive

  • A multi level Space phasor based PWM strategy for an open-end winding induction motor drive using two inverters with different DC link voltages
    4th IEEE International Conference on Power Electronics and Drive Systems. IEEE PEDS 2001 - Indonesia. Proceedings (Cat. No.01TH8594), 2001
    Co-Authors: E.g. Shivakumar, V T Somasekhar, K Gopakumar, K K Mohapatra, L. Umanand, S.k. Sinha
    Abstract:

    An open-end winding induction motor drive fed from two inverters with different DC link voltages is proposed in this paper. A total of 64 voltage Space phasor combinations are possible in this scheme as each inverter produces 8 voltage Space Phasors. The proposed scheme produces voltage Space phasor locations more than that of a 3-level inverter. A total of 37 Space phasor locations are possible from the proposed scheme as compared to 18 voltage Space phasor locations in a 3-level inverter. In the proposed scheme, the induction motor neutral connection is separated (open-end winding) and fed from both the ends. Two 2-level inverters with DC link voltages of 2/3 VDC and 1/3 VDC are used for driving the motor. Here VDC is the conventional 2-level inverter DC link voltage for identical power. A combination of two 2-level inverters with 2/3 VDC and 1/3 VDC DC-link voltages will produce a total of 64 voltage Space phasor combinations in 37 Space phasor locations. For the present scheme a Space phasor based PWM scheme will produce stepped voltage waveforms for the motor phases in different speed ranges. The whole voltage Space phasor locations can be divided into three regions according to the speed range. In the lower speed range the PWM phase voltage will have a six-step envelope (similar to the conventional scheme) and In the middle range the PWM motor phase voltage will have an 12-step envelope and the outer speed range (including the over modulation) the PWM motor phase voltage will have an 18-step envelope. A simple and elegant Space phasor based PWM scheme is proposed in all sectors based on three phase motor reference voltages only. The sector identification is achieved by comparing the components of the motor reference voltages, using simple hysteresis comparators, along the three orthogonal axes to the a,b,c phase axes. The whole scheme is studied for a 1 hp open-end winding motor and the results of the study including the over modulation ranges are presented in this paper.

Umanand L - One of the best experts on this subject based on the ideXlab platform.

  • A Novel Modulation Scheme for a Six Phase Induction Motor with Open-End Windings
    IEEE, 2002
    Co-Authors: K K Mohapatra, V T Somasekhar, Gopakumar K, Umanand L
    Abstract:

    A modulation scheme for a six phase induction motor is presented in this paper. For a six phase induction motor drive harmonics of the order $6n\pm 1(n=1,3,5\hSpace {5mm} etc.,)$ will not contribute to the air gap flux and hence these harmonic currents are limited by the stator impedance only. So harmonic filters are needed for the suppression of these $6n\pm1(n=1,3,5\hSpace{5mm}etc.,)$ high amplitude harmonic currents, when a six phase induction motor is used for variable speed application. In the proposed scheme, a modulation technique to eliminate the $6n\pm1(n=1,3,5\hSpace{5 mm}etc.,)$ harmonic currents, without the need for harmonic filters, from the stator phases of a six phase induction motor drive is explained. An open-end winding drive configuration with DC link voltages, chosen in such away that a 12-sided polygonal voltage Space phasor combinations are achieved for each 3-phase group, independently. A modulation scheme based on 12-sided polygonal voltage Space Phasors will cancel the $6n\pm1(n=1,3,5\hSpace{5mm}etc.,)$ harmonic voltages from all the motor phases and hence currents due to these harmonics will not flow in the motor phases of the six phase machine. The proposed drive scheme is experimentally verified, for variable speed application, using a 1 HP six phase induction motor drive

  • Online estimation of stator resistance of an induction motor for speed control applications
    IEE, 1995
    Co-Authors: Umanand L
    Abstract:

    Speed control of induction motors requires the accurate estimation of the fluxes in the motor. But the flux estimate, when estimated from the stator circuit variables, is dependent on the stator resistance of the induction motor. As a consequence, the flux estimate is prone to errors due to variations in the stator resistance, especially at low stator frequencies. A scheme is presented in this paper for an online estimation of the stator resistance under steady state operating conditions, using variables that can be measured from the terminals of the motor alone. The scheme is based on estimating the steady-state magnitudes of the stator and rotor flux Space Phasors using the reactive power. An analysis of the effect of the stator resistance variations on the flux estimate is presented. A simulation of a rotor field oriented speed control of a VSI-fed induction motor using stator circuit variables is performed incorporating the online stator resistance estimation strategy