EPE Association: EPE 1989 - 39 - Dialogue Session 3.1: PWM CONTROL TECHNIQUES

EPE 1989 - 39 - Dialogue Session 3.1: PWM CONTROL TECHNIQUES
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1989 - Conference > EPE 1989 - 39 - Dialogue Session 3.1: PWM CONTROL TECHNIQUES

   [return to parent folder]

   EFFECTS AND CORRECTION OF SWITCHING DEAD TIMES IN 3-PHASE PWM INVERTER DRIVES
By R.-D. Klug [View]
[Download]

Abstract: The paper describes the effects of the switching dead times avoiding a bridge leg short circuit in pulsewidth modulated (PWM) voltage source inverters (VSI). The consequences on AC variable speed drives with synchronous and asynchronous motors are described by harmonic analysis and by computer simulation (fundamentals and harmonics of motor voltage and current, torque ripple, oszillations). Special attention is payed to the discontinuous motor current mode that can appear at each currents' zero crossing. Different correction possibilities are discussed.

   SWITCHING FREQUENCY OPTIMAL PWM CONTROL OF A THREE-LEVEL INVERTER
By Jürgen K. Steinke [View]
[Download]

Abstract: A PWM method for the control of a three-level inverter is described. Switching frequency optimal-PWM method (SFO- PWM) gives an optimal utilization of mean thyristor switching frequency permitted. The signal processing structure js simple. Though SFO-PWM is suited (or microprocessor applications, signal processing is described for an analogous model. Many applications of three-level-inverters work with a dc-link neutral point not stabilized from power input converter. A neutral point potential control is described, which is capable of stabilizing potential by varying the switching sequences of the three-level inverter itself.

   METHODS OF GENERATING PULSE PATTERNS IN VOLTAGE SOURCE P.W.M. INVERTERS AND IMPLEMENTATION IN AN INDUSTRIAL DRIVE
By P. Sodermanns [View]
[Download]

Abstract: The most important methods used to generate the pulse pattern in voltage-source p.w.m. inverters are outlined and compared. In particular, a comparision is made between the output voltages obtained with the different methods. The regular sampling method is used as the modulation technique in a 16-bit-microprocessor-based inverter control for industrial application, with a sine function extended with the third harmonic as the reference curve. A pulse number of 3 is used in the higher output voltage range. The pulse pattern is calculated on-line.

   VARIABLE OPTIMAL PWM FOR VOLTAGE SOURCE RECTIFIERS AND CURRENT SOURCE INVERTERS
By A. J. Perin; A. A. da Cunha; M. A. de Oliveira [View]
[Download]

Abstract: This paper describes a scheme to create optimal PWM patterns to control the DC output voltage of the three-phase voltage rectifiers with low order harmonics of low amplitude. The line power factor can be kept near unity. The ripple of the DC output voltage decreases with the number of pulses in the modulation period (switching frequency). Identical optimal PWM patterns can be utilized in the current source three-phase inverters with the control of the fundamental output current and elimination of the low order harmonics. The proposed scheme to create the PWM pattern allows the elimination of a great number of low order harmonics. A numerical technique is applied to solve the non-linear equations of the problem. The off-line optimization of the individual switching angles requires a microcomputer. The control circuits of the power semiconductors can be implemented with programable memories and analog and digital circuits, without a microprocessor system. Satisfactory theoretical and experimental results are confirmed.

   COMPARISON OF THE CONTROL MODES FOR PWM VOLTAGE REGULATORS
By P. Maranesi; L. Pinola; G . Volpi; V. Varoli [View]
[Download]

Abstract: Possible control modes in the Cuk, inductor coupled, DC/DC converter are compared on the basis of relevant loop-gain frequency responses. Exact discrete-time modeling shows the delta-V Mode control has the best dynamic characteristics: it allows to fully exploit the inherent possibilities of the converter, and to get significant performance improvements as compared with the basic second order PWM topologies.

   IMPLEMENTATION OF OPTIMISED MODULATION IN AN INDUSTRIAL SPEED DRIVE FOR ASYNCHRONOUS MACHINES
By Eric Sournac; Jean Claude Hapiot; Pascal Maussion; Christophe Sabourin [View]
[Download]

Abstract: This study concerns the speed variations of asynchronous machines using pulse-width modulated inverters. The various constraints like switching losses, the good quality wished for the machine current and the D.C. link current have conducted to the choice of pulse-width modulation techniques by harmonic spectrum optimisation. In order to control the inverter switches, the waveforms of the adopted voltage are determined. The choice of the control module structure is done by considering two actual techniques. The first one consists in memorising the complet pattern, whereas in the second technique only switching angles are memorised. A quantitative study has allowed to opt for the first technique. At last we present the experimental set-up and the corresponding obtained results.

   HOW TO MINIMIZE HARMONICS WITH PULSE WIDTH MODULATION CONTROL
By G. Enjalbert; R. Feuillet; R. Perret [View]
[Download]

Abstract: To decrease the harmonic distortion generated by Pulse Width Modulation technique, it is usual to increase the switching frequency. This paper shows the frequency is limited by the recovery time. Beyond the frequency limit the sinusoidal signal becomes distorded. After describing the C.A.D. package " CIRCUIT " and the Pulse Width Modulation method, simulation waveforms and associated spectra of a single-phase full bridge inverter are presented.

   CALCULATION OF THE PASSIVE AND ACTIVE COMPONENT STRESS OF THREE PHASE PWM CONVERTER SYSTEMS WITH HIGH PULSE RATE
By Johann W. Kolar; Hans Ertl; Franz C. Zach [View]
[Download]

Abstract: This paper treats the simplified purely analytical estimation of the stress of passive and active components of PWM converter systems. The approximation of the actual system behavior thereby is gained according to the generation of limit values or mean values, respectively. This is done by transition from a summation of the "local" contributions of the single pulse periods (related to the interval center) to the integration of a quasi-continuous time function of equal local power loss. The latter function is gained via shifting the pulse interval through the period given by the (voltage or current) fundamental period. A modification of the phase modulation functions allows furthermore the minimization of the harmonic losses on the AC side. (This minimization is immediately clear after transformation of the system variables into space vectors). When compared to harmonic optimal modulation methods known so far the optimization given here results in considerably lower current harmonics rms values in the upper modulation region. Therefore it is especially well applicable to the control of PWM rectifier systems. As the comparison of the approximate solutions and of the results of a digital simulation shows, already for relatively low converter switching frequencies (low compared to the output frequency) a good consistency of the results is given. Therefore, the relationships derived can be applied immediately for the dimensioning of converter systems using FETs, BTs or IGBTs.

   FULLY DIGITAL INSTANTANEOUS PULSES GENERATION. CONTROL ALGORITHM FOR ANY TYPE OF CONVERTERS
By L. A. L. Nozal; J. M. Ruiz; S. Lorenzo; A. Martin [View]
[Download]

Abstract: The development of electronic converters finds a big help with the new power semiconductors devices allowing fast switching. On the other side the theoretical study can know different ways of controlling these devices to obtain good characteristics of harmonic composition. Therefore it's necessary to generate with speed enough the pulses that must control switches of converter. This paper presents an algorithm based on the Modulation of Existence Function Theory. This algorithm obtains an instantaneous pulses generation according with all requirements of the control parameter modulation in the theory above mentioned. The consequence is the design of a digital electronic device -whose hardware and software are explained in this paper too- which has two characteristics until now oposed: high speed and generality: it may be used for any type of converters.

EPE 1989 - 39 - Dialogue Session 3.1: PWM CONTROL TECHNIQUES
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1989 - Conference > EPE 1989 - 39 - Dialogue Session 3.1: PWM CONTROL TECHNIQUES
	[return to parent folder]

	EFFECTS AND CORRECTION OF SWITCHING DEAD TIMES IN 3-PHASE PWM INVERTER DRIVES By R.-D. Klug	[View] [Download]
Abstract: The paper describes the effects of the switching dead times avoiding a bridge leg short circuit in pulsewidth modulated (PWM) voltage source inverters (VSI). The consequences on AC variable speed drives with synchronous and asynchronous motors are described by harmonic analysis and by computer simulation (fundamentals and harmonics of motor voltage and current, torque ripple, oszillations). Special attention is payed to the discontinuous motor current mode that can appear at each currents' zero crossing. Different correction possibilities are discussed.

	SWITCHING FREQUENCY OPTIMAL PWM CONTROL OF A THREE-LEVEL INVERTER By Jürgen K. Steinke	[View] [Download]
Abstract: A PWM method for the control of a three-level inverter is described. Switching frequency optimal-PWM method (SFO- PWM) gives an optimal utilization of mean thyristor switching frequency permitted. The signal processing structure js simple. Though SFO-PWM is suited (or microprocessor applications, signal processing is described for an analogous model. Many applications of three-level-inverters work with a dc-link neutral point not stabilized from power input converter. A neutral point potential control is described, which is capable of stabilizing potential by varying the switching sequences of the three-level inverter itself.

	METHODS OF GENERATING PULSE PATTERNS IN VOLTAGE SOURCE P.W.M. INVERTERS AND IMPLEMENTATION IN AN INDUSTRIAL DRIVE By P. Sodermanns	[View] [Download]
Abstract: The most important methods used to generate the pulse pattern in voltage-source p.w.m. inverters are outlined and compared. In particular, a comparision is made between the output voltages obtained with the different methods. The regular sampling method is used as the modulation technique in a 16-bit-microprocessor-based inverter control for industrial application, with a sine function extended with the third harmonic as the reference curve. A pulse number of 3 is used in the higher output voltage range. The pulse pattern is calculated on-line.

	VARIABLE OPTIMAL PWM FOR VOLTAGE SOURCE RECTIFIERS AND CURRENT SOURCE INVERTERS By A. J. Perin; A. A. da Cunha; M. A. de Oliveira	[View] [Download]
Abstract: This paper describes a scheme to create optimal PWM patterns to control the DC output voltage of the three-phase voltage rectifiers with low order harmonics of low amplitude. The line power factor can be kept near unity. The ripple of the DC output voltage decreases with the number of pulses in the modulation period (switching frequency). Identical optimal PWM patterns can be utilized in the current source three-phase inverters with the control of the fundamental output current and elimination of the low order harmonics. The proposed scheme to create the PWM pattern allows the elimination of a great number of low order harmonics. A numerical technique is applied to solve the non-linear equations of the problem. The off-line optimization of the individual switching angles requires a microcomputer. The control circuits of the power semiconductors can be implemented with programable memories and analog and digital circuits, without a microprocessor system. Satisfactory theoretical and experimental results are confirmed.

	COMPARISON OF THE CONTROL MODES FOR PWM VOLTAGE REGULATORS By P. Maranesi; L. Pinola; G . Volpi; V. Varoli	[View] [Download]
Abstract: Possible control modes in the Cuk, inductor coupled, DC/DC converter are compared on the basis of relevant loop-gain frequency responses. Exact discrete-time modeling shows the delta-V Mode control has the best dynamic characteristics: it allows to fully exploit the inherent possibilities of the converter, and to get significant performance improvements as compared with the basic second order PWM topologies.

	IMPLEMENTATION OF OPTIMISED MODULATION IN AN INDUSTRIAL SPEED DRIVE FOR ASYNCHRONOUS MACHINES By Eric Sournac; Jean Claude Hapiot; Pascal Maussion; Christophe Sabourin	[View] [Download]
Abstract: This study concerns the speed variations of asynchronous machines using pulse-width modulated inverters. The various constraints like switching losses, the good quality wished for the machine current and the D.C. link current have conducted to the choice of pulse-width modulation techniques by harmonic spectrum optimisation. In order to control the inverter switches, the waveforms of the adopted voltage are determined. The choice of the control module structure is done by considering two actual techniques. The first one consists in memorising the complet pattern, whereas in the second technique only switching angles are memorised. A quantitative study has allowed to opt for the first technique. At last we present the experimental set-up and the corresponding obtained results.

	HOW TO MINIMIZE HARMONICS WITH PULSE WIDTH MODULATION CONTROL By G. Enjalbert; R. Feuillet; R. Perret	[View] [Download]
Abstract: To decrease the harmonic distortion generated by Pulse Width Modulation technique, it is usual to increase the switching frequency. This paper shows the frequency is limited by the recovery time. Beyond the frequency limit the sinusoidal signal becomes distorded. After describing the C.A.D. package " CIRCUIT " and the Pulse Width Modulation method, simulation waveforms and associated spectra of a single-phase full bridge inverter are presented.

	CALCULATION OF THE PASSIVE AND ACTIVE COMPONENT STRESS OF THREE PHASE PWM CONVERTER SYSTEMS WITH HIGH PULSE RATE By Johann W. Kolar; Hans Ertl; Franz C. Zach	[View] [Download]
Abstract: This paper treats the simplified purely analytical estimation of the stress of passive and active components of PWM converter systems. The approximation of the actual system behavior thereby is gained according to the generation of limit values or mean values, respectively. This is done by transition from a summation of the "local" contributions of the single pulse periods (related to the interval center) to the integration of a quasi-continuous time function of equal local power loss. The latter function is gained via shifting the pulse interval through the period given by the (voltage or current) fundamental period. A modification of the phase modulation functions allows furthermore the minimization of the harmonic losses on the AC side. (This minimization is immediately clear after transformation of the system variables into space vectors). When compared to harmonic optimal modulation methods known so far the optimization given here results in considerably lower current harmonics rms values in the upper modulation region. Therefore it is especially well applicable to the control of PWM rectifier systems. As the comparison of the approximate solutions and of the results of a digital simulation shows, already for relatively low converter switching frequencies (low compared to the output frequency) a good consistency of the results is given. Therefore, the relationships derived can be applied immediately for the dimensioning of converter systems using FETs, BTs or IGBTs.

	FULLY DIGITAL INSTANTANEOUS PULSES GENERATION. CONTROL ALGORITHM FOR ANY TYPE OF CONVERTERS By L. A. L. Nozal; J. M. Ruiz; S. Lorenzo; A. Martin	[View] [Download]
Abstract: The development of electronic converters finds a big help with the new power semiconductors devices allowing fast switching. On the other side the theoretical study can know different ways of controlling these devices to obtain good characteristics of harmonic composition. Therefore it's necessary to generate with speed enough the pulses that must control switches of converter. This paper presents an algorithm based on the Modulation of Existence Function Theory. This algorithm obtains an instantaneous pulses generation according with all requirements of the control parameter modulation in the theory above mentioned. The consequence is the design of a digital electronic device -whose hardware and software are explained in this paper too- which has two characteristics until now oposed: high speed and generality: it may be used for any type of converters.