EPE Association: EPE 1993 - 05 - Lecture Session L2b: CONTROL AND UNITY PF

EPE 1993 - 05 - Lecture Session L2b: CONTROL AND UNITY PF
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1993 - Conference > EPE 1993 - 05 - Lecture Session L2b: CONTROL AND UNITY PF

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   AN AC-DC CONVERTER WITH LOW INPUT DISTORTION AND NEAR UNITY POWER FACTOR
By M. J. Willers; M. G. Egan; J. M. D. Murphy; S. Daly [View]
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Abstract: In this paper, a single-stage flyback converter is operated as a single-phase ac-dc converter with active power factor correction. The input filter required to reduce the differential mode conducted emissions is examined, and modulation of the switching frequency is suggested as a means of minimising the filter requirements. Various modulation strategies are studied and a simple analogue circuit implementation is presented for the optimum strategy. The influence of component tolerances on harmonic distortion is also investigated.

   CONTROL OF A PWM RECTIFIER IN THE UNBALANCED STATE BY ROBUST VOLTAGE REGULATION
By P. Rioual; H. Pouliquen; J.P. Louis [View]
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Abstract: Disturbances on the network result in costly damage to converters and their loads. A method for desensitizing a PWM rectifier to network disturbances is presented in this article. A converter model covering the unbalanced state is used to analyse the effect of a disturbance. Two robust control methods are proposed to compensate the destabilizing effects of network voltage variations on the DC voltage and the network currents. First, a three-element corrector is used to stabilize the system by positioning poles according to the alpha-stabilitymethod. Secondly, the use of the internal model concept allows to cancel out oscillating disturbances due to network unbalanced. The results presented in this article have been verified by simulations and experiments on a power PWM rectifier using cascade digital control. The electrical load downstream from the converter is no longer disturbed by variation of the network parameters and rectifier operation is stabilized.

   FIELD ORIENTED CONTROL OF A THREE-PHASE INDUCTION MACHINE DRIVEN BY A REGENERATIVE CONVERTER WITH SINUSOIDAL INPUT CURRENT
By J. Rodriguez; J. Pontt; J. Barraza; E. Wiechmann [View]
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Abstract: This paper presents a new converter topology allowing power regeneration from a three-phase induction machine to the single-phase source. At the input side, it has a switch mode rectifier (SMR) composed mainly by two transistors with their antiparalel diodes and two filter capacitors. The output stage has four transistors and four diodes working as an asymmetric inverter. The power semiconductors have the same topology of the well known three-phase voltage source inverter, resulting in a very compact and simple converter. Two control loops are used to control the machine currents. Two additional control loops are used for the control of the input current waveform and for the voltage of the filter capacitors. An additional loop ensures the balancing of capacitors voltages. The method of field orientation, also called vector control, is used to control the speed and flux of the machine. The converter works with practically sinusoidal input current and high power factor (PF > 0.99) and it delivers to the motor balanced three-phase currents with variable frequency and amplitude, having low distortion. The interaction belween converter and motor is studied. The whole control system presents a good dynamic behaviour. Finally, the regeneration capability of the converter is also confirmed.

   DIGITAL STATE CONTROLLERS FOR BRUSHLESS DC-MOTORS AND SQUIRREL CAGE INDUCTION MOTORS
By G. Henneberger; T. Lutter [View]
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Abstract: In this paper digital state controllers are presented which have been developed for a selfcommutated permanent magnet excited synchronous machine and a squirrel cage induction machine. As both machines represent strong nonlinear systems, special assumptions have to be made in order to develop the controllers. In both cases this leads to cascade controllers whereby the structure of these controllers is very similar. In order to achieve steady state precision, observers are used which detect disturbanccs. Here these disturbances have to be interpreted as possible load plus model faults which are caused by modelling the machines. The designed controllers and observers are tested by measurements.

   MODELLING AND CONTROL OF POWER SUPPLIES FOR INDUCTION HEATING
By M. L. Bendaas; J. P. Ferrieux; J. P. Rognon [View]
[Download]

Abstract: This paper deals with the average modelling of induction heating systems. The proposed approach consists of a representation of the real switched system by an average equivalent circuit. In a first step, a large signal and nonlinear model is established; it can be applied to industrial process tracking. Secondly, a linear model, valid for small signals around an operating point is deduced from the previous one. This model allows the design of the controller; however, a study of the robustness is necessary.

EPE 1993 - 05 - Lecture Session L2b: CONTROL AND UNITY PF
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1993 - Conference > EPE 1993 - 05 - Lecture Session L2b: CONTROL AND UNITY PF
	[return to parent folder]

	AN AC-DC CONVERTER WITH LOW INPUT DISTORTION AND NEAR UNITY POWER FACTOR By M. J. Willers; M. G. Egan; J. M. D. Murphy; S. Daly	[View] [Download]
Abstract: In this paper, a single-stage flyback converter is operated as a single-phase ac-dc converter with active power factor correction. The input filter required to reduce the differential mode conducted emissions is examined, and modulation of the switching frequency is suggested as a means of minimising the filter requirements. Various modulation strategies are studied and a simple analogue circuit implementation is presented for the optimum strategy. The influence of component tolerances on harmonic distortion is also investigated.

	CONTROL OF A PWM RECTIFIER IN THE UNBALANCED STATE BY ROBUST VOLTAGE REGULATION By P. Rioual; H. Pouliquen; J.P. Louis	[View] [Download]
Abstract: Disturbances on the network result in costly damage to converters and their loads. A method for desensitizing a PWM rectifier to network disturbances is presented in this article. A converter model covering the unbalanced state is used to analyse the effect of a disturbance. Two robust control methods are proposed to compensate the destabilizing effects of network voltage variations on the DC voltage and the network currents. First, a three-element corrector is used to stabilize the system by positioning poles according to the alpha-stabilitymethod. Secondly, the use of the internal model concept allows to cancel out oscillating disturbances due to network unbalanced. The results presented in this article have been verified by simulations and experiments on a power PWM rectifier using cascade digital control. The electrical load downstream from the converter is no longer disturbed by variation of the network parameters and rectifier operation is stabilized.

	FIELD ORIENTED CONTROL OF A THREE-PHASE INDUCTION MACHINE DRIVEN BY A REGENERATIVE CONVERTER WITH SINUSOIDAL INPUT CURRENT By J. Rodriguez; J. Pontt; J. Barraza; E. Wiechmann	[View] [Download]
Abstract: This paper presents a new converter topology allowing power regeneration from a three-phase induction machine to the single-phase source. At the input side, it has a switch mode rectifier (SMR) composed mainly by two transistors with their antiparalel diodes and two filter capacitors. The output stage has four transistors and four diodes working as an asymmetric inverter. The power semiconductors have the same topology of the well known three-phase voltage source inverter, resulting in a very compact and simple converter. Two control loops are used to control the machine currents. Two additional control loops are used for the control of the input current waveform and for the voltage of the filter capacitors. An additional loop ensures the balancing of capacitors voltages. The method of field orientation, also called vector control, is used to control the speed and flux of the machine. The converter works with practically sinusoidal input current and high power factor (PF > 0.99) and it delivers to the motor balanced three-phase currents with variable frequency and amplitude, having low distortion. The interaction belween converter and motor is studied. The whole control system presents a good dynamic behaviour. Finally, the regeneration capability of the converter is also confirmed.

	DIGITAL STATE CONTROLLERS FOR BRUSHLESS DC-MOTORS AND SQUIRREL CAGE INDUCTION MOTORS By G. Henneberger; T. Lutter	[View] [Download]
Abstract: In this paper digital state controllers are presented which have been developed for a selfcommutated permanent magnet excited synchronous machine and a squirrel cage induction machine. As both machines represent strong nonlinear systems, special assumptions have to be made in order to develop the controllers. In both cases this leads to cascade controllers whereby the structure of these controllers is very similar. In order to achieve steady state precision, observers are used which detect disturbanccs. Here these disturbances have to be interpreted as possible load plus model faults which are caused by modelling the machines. The designed controllers and observers are tested by measurements.

	MODELLING AND CONTROL OF POWER SUPPLIES FOR INDUCTION HEATING By M. L. Bendaas; J. P. Ferrieux; J. P. Rognon	[View] [Download]
Abstract: This paper deals with the average modelling of induction heating systems. The proposed approach consists of a representation of the real switched system by an average equivalent circuit. In a first step, a large signal and nonlinear model is established; it can be applied to industrial process tracking. Secondly, a linear model, valid for small signals around an operating point is deduced from the previous one. This model allows the design of the controller; however, a study of the robustness is necessary.