EPE Association: EPE 1997 – 33: Dialogue Session DS4a: MODULATION STRATEGIES

EPE 1997 – 33: Dialogue Session DS4a: MODULATION STRATEGIES
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1997 - Conference > EPE 1997 – 33: Dialogue Session DS4a: MODULATION STRATEGIES

   [return to parent folder]

   MICROCOMPUTER BASED ON-LINE CONTROL OF A DELTA MODULATED SINE PWM INVERTER
By M. N. Anwar; Md. Bashir Uddin; M. A. Choudhury; M. A. Rahman [View]
[Download]

Abstract: A novel and simple on-line microcomputer generation of PWM waveforms to control static inverters is presented in this paper. On-line implementation is based on newly proposed algebraic equations to calculate switching instants. Implementation has been carried out on an lntel 80386 DX-2 microcomputer using high level turbo C++ language. The system uses keyboard for input, processor for calculation and pin-2 through pin-7 of the parallel port to output switching pulses. The implementation allows on-line variations of modulation parameters of the delta modulation technique. In this paper the proposed method is described with analysis and results of three-phase inverter operation with resistive loads.

   HARMONIC EVALUATION OF TWO-LEVEL CARRIER-BASED PWM METHODS
By S. Fukuda; K. Suzuki [View]
[Download]

Abstract: This paper describes harmonic evaluation of three phase carrier-based PWM inverters, in which the harmonic distortion determining factor (HDDF) is used as the basis. HDDF represents the intrinsic spectral property of individual PWM methods. Nine PWM methods are compared and evaluated. It is concluded that in terms of RMS values of the harmonic currents or torque ripples of driven motors, the third harmonic injected sine PWM, the two-phase modulation PWM and the space vector PWM methods exhibit excellent performance.

   SPACE VECTOR MODULATION IN ORTHOGONAL AND NATURAL FRAMES INCLUDING THE OVERMODULATION RANGE
By A. Haras [View]
[Download]

Abstract: The paper reviews the general relations of vector PWM on the basis of conventional, polar notation of the space vector. Vector amplitude and position is used, in this case, to compute vector on-duration and commutation delays for the inverter. Two other notations are proposed in the paper: on the basis of stationary ab co-ordinates and in abc frame. Very simple relations are obtained for vector on-duration when using abc frame. Commutation delays can be calculated directly from abc phase voltages of the machine. It is shown in the paper that space vector PWM is equivalent to the carrier PWM, with modulating signal composed of a sinus and triple harmonic in the form very close to a triangle. Overmodulation strategy based on the correction of commutation delays. is presented. Gate pulse minimum time is always under control. Real position and amplitude of space vector in the overmodulation are presented.

   COMPARATIVE INVESTIGATION OF RANDOM PWM TECHNIQUES WITH VARIABLE SWITCHING FREQUENCY AND PULSE POSITION FOR INVERTER-FED INDUCTION MOTORS
By M. Becht; F. Blaabjergt; J. K. Pedersent; A. M. Trzynadlowski [View]
[Download]

Abstract: This paper compares experimentally two different random modulation techniques for inverter-fed induction motors. The first technique is random switching frequency modulation and the seco.nd is random pulse position modulation. The comparison is done on the basis that the switching losses are fixed in the inverter and the traditional space vector modulation is used as a reference with 5kHz switching frequency. Methods to determine the average inverter pulse frequency and how to generate random switching frequencies with uniform density are also presented. The experimental results show fixed switching frequency operation and random pulse position give most distinct harmonics in both current, voltage and sound spectra. Random switching frequency with a frequency band of 5 kHz gives more distributed spectra that in some cases are less annoying. However, there is also a higher risk to trigger resoriances.

   SYNTHESIS OF LOGIC CONNECTION CONTROLLERS FOR MATRIX CONVERTERS
By H. Ralaivao; J.-P. Cambronne; B. Francois; J.-P. Hautier [View]
[Download]

Abstract: A particular analysis of dependencies between the switches states and the levels of conversion in matrix converters is detailed. A design of the logic interface between these variables is deduced. The homopolar components which are injected in the electrical references then appear as parameters for the optimisation of the command of matrix converters. This paper also shows the importance of the control parameters to make the modulation and the command switches easier to function.

   SINUSOIDAL WAVEFORM GENERATION BASED ON DSP IMPLEMENTATION
By V. Navrapescu; A. Craciunescu; D. O. Kisck [View]
[Download]

Abstract: The arrival of cheapest and more powerful digital signal processors, has allowed the development of new methods for the generation of PWM waveforms with a higher accuracy. This paper presents a new method for generation of a PWM waveform based on an implementation with DSP's. Furthermore the simulation of an a.c. drive with an induction machine fed from a PWM voltage source inverter is presented. The experiment results are presented next.

   DIGITAL SCALAR PULSE WIDTH MODULATION: A SIMPLE APPROACH TO INTRODUCE NON-SINUSOIDAL MODULATING WAVEFORMS
By C. B. Jacobina; A. M. N. Lima; E. R. C. da Silva; R. N. C. Alves; P. F. Seixas [View]
[Download]

Abstract: This paper shows the complete relation to obtain the equivalence between scalar, vector and carrier-based approaches. From this equivalence a microprocessor-based scheme which uses standard timer circuits and a simple software algorithm is proposed to implement the scalar modulation. The proposed scalar technique provides a systematic way to introduce non-sinusoidal modulating waveforms to improve the performance of the pulse width modulator. Simulated results demonstrate the validity of the proposed methods.

   IMPROVED HARMONIC SPECTRUM AND REDUCED EMI IN BOOST CONVERTER BY USING THE RANDOM MODULATION
By F. Mihalic; T. Bezjak; M. Milanovic [View]
[Download]

Abstract: Higher operating frequency and simpler drive requirements provide rising output power from modern power electronics devices. Nevertheless, the switch-mode operation results in Electromagnetic Interference (EMI) which is produced due to large di/dt and dv/dt. One way to reduce the EMI is the use of classic and expensive input filters or include the active filter into the power circuits. By using of randomized pulse width modulation (RPWM) the EMI effect can be reduced and implementation of the proposed control scheme into the boost converter improve the harmonic spectrum as well. Such approach enable to control the levels of spectral lines in harmonics spectrum. Simulated and measured current spectrum withoutand with used random modulation will be shown in this paper. Such random modulated boost converter has improved harmonic spectrum and reduced EMI effect as well.

   NOVEL SPACE VECTOR MODULATION STRATEGY FOR A FOUR-SWITCH THREEPHASE DC/ AC INVERTER
By D. T. W. Liang; J. Li [View]
[Download]

Abstract: A novel spaee flux vector modulation strategy for a four-switch three-phase dc/ac inverter is presented. The modulation strategy maintains a constant circular stator flux in real-time by selectively switching among the four possible voltage vectors. The scheme can be implemented using low-cost microcontroller chip and yet maintain a fast optimum switching frequency with minimum associated switching loss. Both simulation and experimental results are presented.

   COMPARISON OF MODULATION STRATEGIES FOR B4-INVERTERS
By F. Blaabjerg; H. Kraght; D. O. Neacsu; J. K. Pedersen [View]
[Download]

Abstract: This paper compares different modulation strategies for the component minimized based B4-inverter where the application is an induction motor. The modulation strategies are based on different space vector methods and the comparison is made between performance parameters like total harmonic distortion, voltage spectra and torque ripple. A review of existing methods are made. Both simulation and experimental results are shown. It is concluded one modulation method is the best concerning torque ripple and other performance parameters.

EPE 1997 – 33: Dialogue Session DS4a: MODULATION STRATEGIES
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1997 - Conference > EPE 1997 – 33: Dialogue Session DS4a: MODULATION STRATEGIES
	[return to parent folder]

	MICROCOMPUTER BASED ON-LINE CONTROL OF A DELTA MODULATED SINE PWM INVERTER By M. N. Anwar; Md. Bashir Uddin; M. A. Choudhury; M. A. Rahman	[View] [Download]
Abstract: A novel and simple on-line microcomputer generation of PWM waveforms to control static inverters is presented in this paper. On-line implementation is based on newly proposed algebraic equations to calculate switching instants. Implementation has been carried out on an lntel 80386 DX-2 microcomputer using high level turbo C++ language. The system uses keyboard for input, processor for calculation and pin-2 through pin-7 of the parallel port to output switching pulses. The implementation allows on-line variations of modulation parameters of the delta modulation technique. In this paper the proposed method is described with analysis and results of three-phase inverter operation with resistive loads.

	HARMONIC EVALUATION OF TWO-LEVEL CARRIER-BASED PWM METHODS By S. Fukuda; K. Suzuki	[View] [Download]
Abstract: This paper describes harmonic evaluation of three phase carrier-based PWM inverters, in which the harmonic distortion determining factor (HDDF) is used as the basis. HDDF represents the intrinsic spectral property of individual PWM methods. Nine PWM methods are compared and evaluated. It is concluded that in terms of RMS values of the harmonic currents or torque ripples of driven motors, the third harmonic injected sine PWM, the two-phase modulation PWM and the space vector PWM methods exhibit excellent performance.

	SPACE VECTOR MODULATION IN ORTHOGONAL AND NATURAL FRAMES INCLUDING THE OVERMODULATION RANGE By A. Haras	[View] [Download]
Abstract: The paper reviews the general relations of vector PWM on the basis of conventional, polar notation of the space vector. Vector amplitude and position is used, in this case, to compute vector on-duration and commutation delays for the inverter. Two other notations are proposed in the paper: on the basis of stationary ab co-ordinates and in abc frame. Very simple relations are obtained for vector on-duration when using abc frame. Commutation delays can be calculated directly from abc phase voltages of the machine. It is shown in the paper that space vector PWM is equivalent to the carrier PWM, with modulating signal composed of a sinus and triple harmonic in the form very close to a triangle. Overmodulation strategy based on the correction of commutation delays. is presented. Gate pulse minimum time is always under control. Real position and amplitude of space vector in the overmodulation are presented.

	COMPARATIVE INVESTIGATION OF RANDOM PWM TECHNIQUES WITH VARIABLE SWITCHING FREQUENCY AND PULSE POSITION FOR INVERTER-FED INDUCTION MOTORS By M. Becht; F. Blaabjergt; J. K. Pedersent; A. M. Trzynadlowski	[View] [Download]
Abstract: This paper compares experimentally two different random modulation techniques for inverter-fed induction motors. The first technique is random switching frequency modulation and the seco.nd is random pulse position modulation. The comparison is done on the basis that the switching losses are fixed in the inverter and the traditional space vector modulation is used as a reference with 5kHz switching frequency. Methods to determine the average inverter pulse frequency and how to generate random switching frequencies with uniform density are also presented. The experimental results show fixed switching frequency operation and random pulse position give most distinct harmonics in both current, voltage and sound spectra. Random switching frequency with a frequency band of 5 kHz gives more distributed spectra that in some cases are less annoying. However, there is also a higher risk to trigger resoriances.

	SYNTHESIS OF LOGIC CONNECTION CONTROLLERS FOR MATRIX CONVERTERS By H. Ralaivao; J.-P. Cambronne; B. Francois; J.-P. Hautier	[View] [Download]
Abstract: A particular analysis of dependencies between the switches states and the levels of conversion in matrix converters is detailed. A design of the logic interface between these variables is deduced. The homopolar components which are injected in the electrical references then appear as parameters for the optimisation of the command of matrix converters. This paper also shows the importance of the control parameters to make the modulation and the command switches easier to function.

	SINUSOIDAL WAVEFORM GENERATION BASED ON DSP IMPLEMENTATION By V. Navrapescu; A. Craciunescu; D. O. Kisck	[View] [Download]
Abstract: The arrival of cheapest and more powerful digital signal processors, has allowed the development of new methods for the generation of PWM waveforms with a higher accuracy. This paper presents a new method for generation of a PWM waveform based on an implementation with DSP's. Furthermore the simulation of an a.c. drive with an induction machine fed from a PWM voltage source inverter is presented. The experiment results are presented next.

	DIGITAL SCALAR PULSE WIDTH MODULATION: A SIMPLE APPROACH TO INTRODUCE NON-SINUSOIDAL MODULATING WAVEFORMS By C. B. Jacobina; A. M. N. Lima; E. R. C. da Silva; R. N. C. Alves; P. F. Seixas	[View] [Download]
Abstract: This paper shows the complete relation to obtain the equivalence between scalar, vector and carrier-based approaches. From this equivalence a microprocessor-based scheme which uses standard timer circuits and a simple software algorithm is proposed to implement the scalar modulation. The proposed scalar technique provides a systematic way to introduce non-sinusoidal modulating waveforms to improve the performance of the pulse width modulator. Simulated results demonstrate the validity of the proposed methods.

	IMPROVED HARMONIC SPECTRUM AND REDUCED EMI IN BOOST CONVERTER BY USING THE RANDOM MODULATION By F. Mihalic; T. Bezjak; M. Milanovic	[View] [Download]
Abstract: Higher operating frequency and simpler drive requirements provide rising output power from modern power electronics devices. Nevertheless, the switch-mode operation results in Electromagnetic Interference (EMI) which is produced due to large di/dt and dv/dt. One way to reduce the EMI is the use of classic and expensive input filters or include the active filter into the power circuits. By using of randomized pulse width modulation (RPWM) the EMI effect can be reduced and implementation of the proposed control scheme into the boost converter improve the harmonic spectrum as well. Such approach enable to control the levels of spectral lines in harmonics spectrum. Simulated and measured current spectrum withoutand with used random modulation will be shown in this paper. Such random modulated boost converter has improved harmonic spectrum and reduced EMI effect as well.

	NOVEL SPACE VECTOR MODULATION STRATEGY FOR A FOUR-SWITCH THREEPHASE DC/ AC INVERTER By D. T. W. Liang; J. Li	[View] [Download]
Abstract: A novel spaee flux vector modulation strategy for a four-switch three-phase dc/ac inverter is presented. The modulation strategy maintains a constant circular stator flux in real-time by selectively switching among the four possible voltage vectors. The scheme can be implemented using low-cost microcontroller chip and yet maintain a fast optimum switching frequency with minimum associated switching loss. Both simulation and experimental results are presented.

	COMPARISON OF MODULATION STRATEGIES FOR B4-INVERTERS By F. Blaabjerg; H. Kraght; D. O. Neacsu; J. K. Pedersen	[View] [Download]
Abstract: This paper compares different modulation strategies for the component minimized based B4-inverter where the application is an induction motor. The modulation strategies are based on different space vector methods and the comparison is made between performance parameters like total harmonic distortion, voltage spectra and torque ripple. A review of existing methods are made. Both simulation and experimental results are shown. It is concluded one modulation method is the best concerning torque ripple and other performance parameters.