EPE Association: EPE 1993 - 48 - Dialogue Session DS3.6: SYSTEM ENGINEERING: HARMONICS, EMC / RFI, UPF SYSTEMS

EPE 1993 - 48 - Dialogue Session DS3.6: SYSTEM ENGINEERING: HARMONICS, EMC / RFI, UPF SYSTEMS
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1993 - Conference > EPE 1993 - 48 - Dialogue Session DS3.6: SYSTEM ENGINEERING: HARMONICS, EMC / RFI, UPF SYSTEMS

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   A NOVEL STRUCTURE OF MULTI-LEVEL HIGH VOLTAGE SOURCE INVERTER
By Young-Seok Kim; Beom-Seok Seo; Dong-Seok Hyun [View]
[Download]

Abstract: This paper deals with a new multi-level high voltage source inverter with GTO Thyristors. Recently, a multi-level approach seems to be best suited for implementing high voltage conversion system because it leads to harmonic reduction and deals with safely high power conversion system independent of the dynamic switching characteristics of each power semiconductor device. However, a conventional multi-level inverter has some problems: voltage unbalance between DC-link capacitors and overvoltages across the inner switching devices. Therefore, we propose a novel structure of a multi-level inverter improving these problems.

   E.M.I. TESTS ON A BRUSHLESS ACTUATOR: COMPARISON OF DIFFERENT OPERATION MODES
By J. Cros; S. Astier; J. M. Vinassa; M. Lajoie-Mazenc; J. P. Berry [View]
[Download]

Abstract: In this paper, we present the results EMI tests made on a permanent magnet brushless DC actuator designed for an automotive application. This actuator is fed by a current control PWM voltage source inverter. The described tests allow to compare the influence of different operation modes on electromagnetic interferences: the use of two types of push-pull drivers with or without control of voltage and current gradients during commutations times, the use of two current regulation types with constant frequency chopping or hysteresis control and use of two modulation ways by means of either one or two chopping transistors.

   A COMBINED BUCK AND BOOST POWER-FACTOR-CONTROLLER FOR THREE-PHASE INPUT
By Berthold Fuld; Siegfried Kern; Ray Ridley [View]
[Download]

Abstract: Power factor controllers presented in the past are mostly either boost-type (with high output voltage) or buck-type (with low output voltage) [1]. An alternate solution is a combination of a buck and a boost stage, giving important advantages at high input voltage
- Favourable output voltage, e.g. 400 V
- Wide input voltage range
- No additional inrush limiter necessary
For three-phase input, it is possible to use three single phase units connected each to two phases (line-to-line). Since the busses have different voltages to ground, it is not possible to connect them. Therefore it is necessary to use DC/DC converters with loadsharing to get equal input currents. The control is simple: a conventional PFC-controller is augmented by an additional current loop and a circuit which switches between the two stages.

   CAPACITOR VOLTAGE CONTROL IN SINGLE-PHASE THREE-LEVEL PWM CONVERTERS
By J. Carter; C. J. Goodman; H. Zelaya; S. C. Tran [View]
[Download]

Abstract: This paper describes the circuit topology of the three-level single-phase pulse converter, and lists its advantages over two-level converters. Different modulation schemes which achieve PWM switching of the converter are described. A preferred scheme is selected on the basis of simplicity and symmetry. For this scheme the effect of odd and even modulation ratios is discussed in detail. The effect of unbalanced circuit conditions on the capacitor voltage sharing is described. An algorithm to maintain equal capacitor voltage even under unbalanced conditions is proposed. The results are obtained using the Saber mixed-mode simulator.

   APPLICATION OF STOCHASTIC ANALYSES TO EMC PROBLEMS
By Yu. M. Bykov; V. Vasilenko [View]
[Download]

Abstract: The paper presents stochastic methods as applied to power electronic systems when deterministic approach brings about particular or inconvenient for use results. Such a problem is an electromagnetic compatability (EMC) of convertible power source and converted power consumer with cycloconverter. Two cycloconverter systems (Variable Speed - Constant Frequency VSCF and Constant Speed - Variable Frequency CSVF) are considered onder power source and commutator control signal voltage and frequency disturbances. Essentially, disturbances may be separated to: (a) "weak" and fast stochastic and (b) "strong" and slow deterministic. That allows to introduce an "instant" power spectrum of the process defined by fluctuations at each value of the "strong" disturbance. The paper deals with a power spectrum analysis method based solely on "strong" random after-effects of fluctuations. Then the process may be related to the category of pulse random processes with constant period. Common method is applied for analitic definition or cycloconverter output spectrum. Obtained are simple formulae which have been used for calculation of output voltage/current power spectra onder fluctuations and strong disturbances In the VSCF and CSVF systems.

   INTEGRAL ASSESSMENT CRITERION OF COMMUTATION MARGIN IN LINE COMMUTATED THYRISTOR INVERTER AT STATES OF ASYMMETRY IN THE POWER SYSTEM
By L. Frackowiak; G. Plenzler; J. Zyborski [View]
[Download]

Abstract: Line commutated thyristor inverters used to energy transmission to the power system from DC constant voltage sources (e.g. MHD generator, regenerative load testing of large internal combustion engines, etc.) need special control procedure against AC fault conditions. The paper proposes a new original system to determination of the minimum angle of thyristors triggering advance at short circuits. The system being reported predicts required commutation margin. It analyses current load and time integral of wave form of commutation voltage. The paper presents schematic block diagram and performance of the inverter control system at different states of operation. Theoretical considerations are illustrated by exemplary wave forms of inverter current and thyristor voltages at faults in the power system. The wave forms were obtained by digital simulation. The reported inverter system is immune to the states of voltage asymmetry in AC mains. It can co-operate with either synchronous or asynchronous controller.

   COMMON MODE RFI OF A HF POWER CONVERTER: PHENOMENON, ITS MODELLING AND ITS MEASUREMENT
By R. Scheich; J. Roudet; S. Bigot; J. P. Ferrieux [View]
[Download]

Abstract: The search for higher switching frequencies in power electronics allows magnetic components to be minimized but also enhances the spectrum of electromagnetic interferences engendered by interaction of the power structure and its active components; hence the need for investigation in the interference phenomena. This paper deals with the modelling and the measurement of one of the phenomena occuring, the common mode current its origin and its propagation in a chopper structure are highlighted, and a simple equivalent circuit is derived enabling noise level prediction. The exciting signal is the voltage over the switch. lts Fourier transform applied to the transfer function yields the noise signal time domain waveform and the corresponding frequency spectrum level. These theoretical results are compared to power circuit simulation and to time and frequency domain waveforms monitored on an experimental set-up. Further investigations could include more accurate models of the components and be extended to other structures.

   SPACE VECTOR CONTROL OF MATRIX CONVERTERS WITH UNITY INPUT POWER FACTOR AND SINUSOIDAL INPUT/OUTPUT WAVEFORMS
By D. Casadei; G. Grandi; G. Serra; A. Tani [View]
[Download]

Abstract: In this paper the control of a three phase ac-ac matrix converter with sinusoidal input and output waveforms and unity power factor at the input side is presented. The control strategy bas been developed utilising the space vector modulation technique. This approach has the advantage of an immediate comprehension of the switching strategies. The maximum value V3/2 of the voltage transfer ratio is achieved without considering any third harmonic voltage component. The number of switch commutations within a cycle period can be limited utilising an opportune commutation sequence. Furthermore, safe commutation is achieved by current sensing. A numerical simulation of the overall system has been carried out and the numerical results are presented to verify the operating principle.

   DIGITAL POWER FACTOR CORRECTION WITH NON-SINEWAVE CURRENT
By P. Guillemin; J. M. Charreton; B. Maurice [View]
[Download]

Abstract: Following the emergence of European and International standards concerning Power Factor and giving new limits to current harmonics content, electronic designers have to face the Power Factor Correction (P.F.C.) problem. This paper gives an example of a pre-regulator on 230V mains in which the harmonic correction function is made by software using a standard micro-controller. This application, well-suited in the power range below one thousand Watts, allows flexible adaptation to specific application features and avoids the use of P.F.C. dedicated ICs. Showing that such an incomplete harmonic compensation is a realistic solution in this power range, the author describes principle and method to generate the adequate current waveform to be drawn from the mains. The closed loop voltage regulation, made by software is also described. It can be easily adapted to different types of loads. Practical results are given.

   CONTROLLABILITY OF THE SIMPLE THREE PHASE RECTIFIER OPERATING WITH UNITY POWER FACTOR
By W. Koczara; P. Bialoskorski [View]
[Download]

Abstract: The simple a 3 transistors (3 T) and 18 diode (18D) system supply dc voltage operates as a three phase controlled rectifier (TPCR). The rectifier ac input current is nearly sinusoidal and its displacement angle is equal to 0. As the system is symmetrical the analysis of current control is described only for an angle pi/3 i.e. 0< wt< pi/3. The method of comparison per unit reference and available space vector current derivatives gives information about ability to control: sinusoidal amplitude of supply ac current, displacement angle and output dc voltage as a function of ac side inductance and per unit load current. The unity power factor is a main state of rectifier, however the leading and lagging operation is possible too. The analysis results, simulation study and laboratory tests of the TPCR rectifier system are presented.

   ALTERNATIVE POWER DISTRIBUTION IN RESIDENTIAL AND COMMERCIAL BUILDINGS
By J. A. Ferreira; H. W. van der Broeck [View]
[Download]

Abstract: Historically 220V/50Hz or 110V/60Hz have become the standard for power distribution in residential and commercial buildings. During the past decades the number of electronic appliances increased rapidly, and the state of art is currently that almost all consumer equipment contain electronics. Electronic circuits prefer DC supplies and the sinusoidal line voltage complicates the construction of power supplies, since rectifiers cause current distortion and EMI problems. Thus, this report investigates the suitability of different waveforms for the residential power network of the future. Three alternative voltage wave forms have been studied. These are a DC voltage, a 20kHz square wave voltage and a 50Hz square wave voltage. It bas been investigated whether these systems are compatible to the present mains and to todays appliances and consumer products. A power conditioner is described which is capable to provide the considered waveforms. Finally some measurements have been taken to illustrate the performance of alternative distribution systems.

   RADIATED AND CONDUCTED INTERFERENCES IN INDUCTION HEATING EQUIPMENT: CHARACTERISTICS AND REMEDIES
By J. Nuns; H. Foch; M. Metz; X. Yang [View]
[Download]

Abstract: This paper describes all the disturbances resulting from induction heating equipment, and practical methods to deal with the problems in order that induction heating processes can handle disturbances by themselves, and be made more cost-effective. After a great number of measurements and a detail study to a lot of industrial installations, principal mechanisms of the interferences have been revealed. For harmonic distortion, useful solutions have been proposed, some of which are industrially tested or used by manufacturers. The proposed dual Steinmetz Bridge can thoroughly resolve both capacitor switching problem and harmonic amplification in a non-linear load or in a polluted network. A current type inverter is particularly realized in 'spread' type for the high frequency study. On basis of interference mechanisms, practical solutions such as damping reactor, common mode current bypass, and non-linear snubber have been proposed and confirmed in a 'compacted' type inverter. The best way for attenuating the interferences is to dispose at sources and transform them into thermal energy. By understanding mechanism, we can always find some pre-measures to deal with the problems, which are undoubtedly cheaper than that of post-remedies.

   THE PREDICTION OF SUPPLY CURRENT WAVEFORMS AND HARMONICS FOR RECTIFIER CIRCUITS WITH CAPACITIVE SMOOTHING
By J. C. Clare; R. M. Davis [View]
[Download]

Abstract: Most equipment using capacitively smoothed rectification will shortly be subject to regulations limiting the allowable amplitudes of supply current harmonics. A method for rapidly computing the harmonic amplitudes based on an analytical function for the current waveform is presented. The analysis includes supply inductance and resistance and the effects of non-infinite dc aide smoothing capacitance. The use of supply side impedance to control harmonic content is discussed and quantitative results for a range of load powers are given.

EPE 1993 - 48 - Dialogue Session DS3.6: SYSTEM ENGINEERING: HARMONICS, EMC / RFI, UPF SYSTEMS
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1993 - Conference > EPE 1993 - 48 - Dialogue Session DS3.6: SYSTEM ENGINEERING: HARMONICS, EMC / RFI, UPF SYSTEMS
	[return to parent folder]

	A NOVEL STRUCTURE OF MULTI-LEVEL HIGH VOLTAGE SOURCE INVERTER By Young-Seok Kim; Beom-Seok Seo; Dong-Seok Hyun	[View] [Download]
Abstract: This paper deals with a new multi-level high voltage source inverter with GTO Thyristors. Recently, a multi-level approach seems to be best suited for implementing high voltage conversion system because it leads to harmonic reduction and deals with safely high power conversion system independent of the dynamic switching characteristics of each power semiconductor device. However, a conventional multi-level inverter has some problems: voltage unbalance between DC-link capacitors and overvoltages across the inner switching devices. Therefore, we propose a novel structure of a multi-level inverter improving these problems.

	E.M.I. TESTS ON A BRUSHLESS ACTUATOR: COMPARISON OF DIFFERENT OPERATION MODES By J. Cros; S. Astier; J. M. Vinassa; M. Lajoie-Mazenc; J. P. Berry	[View] [Download]
Abstract: In this paper, we present the results EMI tests made on a permanent magnet brushless DC actuator designed for an automotive application. This actuator is fed by a current control PWM voltage source inverter. The described tests allow to compare the influence of different operation modes on electromagnetic interferences: the use of two types of push-pull drivers with or without control of voltage and current gradients during commutations times, the use of two current regulation types with constant frequency chopping or hysteresis control and use of two modulation ways by means of either one or two chopping transistors.

	A COMBINED BUCK AND BOOST POWER-FACTOR-CONTROLLER FOR THREE-PHASE INPUT By Berthold Fuld; Siegfried Kern; Ray Ridley	[View] [Download]
Abstract: Power factor controllers presented in the past are mostly either boost-type (with high output voltage) or buck-type (with low output voltage) [1]. An alternate solution is a combination of a buck and a boost stage, giving important advantages at high input voltage - Favourable output voltage, e.g. 400 V - Wide input voltage range - No additional inrush limiter necessary For three-phase input, it is possible to use three single phase units connected each to two phases (line-to-line). Since the busses have different voltages to ground, it is not possible to connect them. Therefore it is necessary to use DC/DC converters with loadsharing to get equal input currents. The control is simple: a conventional PFC-controller is augmented by an additional current loop and a circuit which switches between the two stages.

	CAPACITOR VOLTAGE CONTROL IN SINGLE-PHASE THREE-LEVEL PWM CONVERTERS By J. Carter; C. J. Goodman; H. Zelaya; S. C. Tran	[View] [Download]
Abstract: This paper describes the circuit topology of the three-level single-phase pulse converter, and lists its advantages over two-level converters. Different modulation schemes which achieve PWM switching of the converter are described. A preferred scheme is selected on the basis of simplicity and symmetry. For this scheme the effect of odd and even modulation ratios is discussed in detail. The effect of unbalanced circuit conditions on the capacitor voltage sharing is described. An algorithm to maintain equal capacitor voltage even under unbalanced conditions is proposed. The results are obtained using the Saber mixed-mode simulator.

	APPLICATION OF STOCHASTIC ANALYSES TO EMC PROBLEMS By Yu. M. Bykov; V. Vasilenko	[View] [Download]
Abstract: The paper presents stochastic methods as applied to power electronic systems when deterministic approach brings about particular or inconvenient for use results. Such a problem is an electromagnetic compatability (EMC) of convertible power source and converted power consumer with cycloconverter. Two cycloconverter systems (Variable Speed - Constant Frequency VSCF and Constant Speed - Variable Frequency CSVF) are considered onder power source and commutator control signal voltage and frequency disturbances. Essentially, disturbances may be separated to: (a) "weak" and fast stochastic and (b) "strong" and slow deterministic. That allows to introduce an "instant" power spectrum of the process defined by fluctuations at each value of the "strong" disturbance. The paper deals with a power spectrum analysis method based solely on "strong" random after-effects of fluctuations. Then the process may be related to the category of pulse random processes with constant period. Common method is applied for analitic definition or cycloconverter output spectrum. Obtained are simple formulae which have been used for calculation of output voltage/current power spectra onder fluctuations and strong disturbances In the VSCF and CSVF systems.

	INTEGRAL ASSESSMENT CRITERION OF COMMUTATION MARGIN IN LINE COMMUTATED THYRISTOR INVERTER AT STATES OF ASYMMETRY IN THE POWER SYSTEM By L. Frackowiak; G. Plenzler; J. Zyborski	[View] [Download]
Abstract: Line commutated thyristor inverters used to energy transmission to the power system from DC constant voltage sources (e.g. MHD generator, regenerative load testing of large internal combustion engines, etc.) need special control procedure against AC fault conditions. The paper proposes a new original system to determination of the minimum angle of thyristors triggering advance at short circuits. The system being reported predicts required commutation margin. It analyses current load and time integral of wave form of commutation voltage. The paper presents schematic block diagram and performance of the inverter control system at different states of operation. Theoretical considerations are illustrated by exemplary wave forms of inverter current and thyristor voltages at faults in the power system. The wave forms were obtained by digital simulation. The reported inverter system is immune to the states of voltage asymmetry in AC mains. It can co-operate with either synchronous or asynchronous controller.

	COMMON MODE RFI OF A HF POWER CONVERTER: PHENOMENON, ITS MODELLING AND ITS MEASUREMENT By R. Scheich; J. Roudet; S. Bigot; J. P. Ferrieux	[View] [Download]
Abstract: The search for higher switching frequencies in power electronics allows magnetic components to be minimized but also enhances the spectrum of electromagnetic interferences engendered by interaction of the power structure and its active components; hence the need for investigation in the interference phenomena. This paper deals with the modelling and the measurement of one of the phenomena occuring, the common mode current its origin and its propagation in a chopper structure are highlighted, and a simple equivalent circuit is derived enabling noise level prediction. The exciting signal is the voltage over the switch. lts Fourier transform applied to the transfer function yields the noise signal time domain waveform and the corresponding frequency spectrum level. These theoretical results are compared to power circuit simulation and to time and frequency domain waveforms monitored on an experimental set-up. Further investigations could include more accurate models of the components and be extended to other structures.

	SPACE VECTOR CONTROL OF MATRIX CONVERTERS WITH UNITY INPUT POWER FACTOR AND SINUSOIDAL INPUT/OUTPUT WAVEFORMS By D. Casadei; G. Grandi; G. Serra; A. Tani	[View] [Download]
Abstract: In this paper the control of a three phase ac-ac matrix converter with sinusoidal input and output waveforms and unity power factor at the input side is presented. The control strategy bas been developed utilising the space vector modulation technique. This approach has the advantage of an immediate comprehension of the switching strategies. The maximum value V3/2 of the voltage transfer ratio is achieved without considering any third harmonic voltage component. The number of switch commutations within a cycle period can be limited utilising an opportune commutation sequence. Furthermore, safe commutation is achieved by current sensing. A numerical simulation of the overall system has been carried out and the numerical results are presented to verify the operating principle.

	DIGITAL POWER FACTOR CORRECTION WITH NON-SINEWAVE CURRENT By P. Guillemin; J. M. Charreton; B. Maurice	[View] [Download]
Abstract: Following the emergence of European and International standards concerning Power Factor and giving new limits to current harmonics content, electronic designers have to face the Power Factor Correction (P.F.C.) problem. This paper gives an example of a pre-regulator on 230V mains in which the harmonic correction function is made by software using a standard micro-controller. This application, well-suited in the power range below one thousand Watts, allows flexible adaptation to specific application features and avoids the use of P.F.C. dedicated ICs. Showing that such an incomplete harmonic compensation is a realistic solution in this power range, the author describes principle and method to generate the adequate current waveform to be drawn from the mains. The closed loop voltage regulation, made by software is also described. It can be easily adapted to different types of loads. Practical results are given.

	CONTROLLABILITY OF THE SIMPLE THREE PHASE RECTIFIER OPERATING WITH UNITY POWER FACTOR By W. Koczara; P. Bialoskorski	[View] [Download]
Abstract: The simple a 3 transistors (3 T) and 18 diode (18D) system supply dc voltage operates as a three phase controlled rectifier (TPCR). The rectifier ac input current is nearly sinusoidal and its displacement angle is equal to 0. As the system is symmetrical the analysis of current control is described only for an angle pi/3 i.e. 0< wt< pi/3. The method of comparison per unit reference and available space vector current derivatives gives information about ability to control: sinusoidal amplitude of supply ac current, displacement angle and output dc voltage as a function of ac side inductance and per unit load current. The unity power factor is a main state of rectifier, however the leading and lagging operation is possible too. The analysis results, simulation study and laboratory tests of the TPCR rectifier system are presented.

	ALTERNATIVE POWER DISTRIBUTION IN RESIDENTIAL AND COMMERCIAL BUILDINGS By J. A. Ferreira; H. W. van der Broeck	[View] [Download]
Abstract: Historically 220V/50Hz or 110V/60Hz have become the standard for power distribution in residential and commercial buildings. During the past decades the number of electronic appliances increased rapidly, and the state of art is currently that almost all consumer equipment contain electronics. Electronic circuits prefer DC supplies and the sinusoidal line voltage complicates the construction of power supplies, since rectifiers cause current distortion and EMI problems. Thus, this report investigates the suitability of different waveforms for the residential power network of the future. Three alternative voltage wave forms have been studied. These are a DC voltage, a 20kHz square wave voltage and a 50Hz square wave voltage. It bas been investigated whether these systems are compatible to the present mains and to todays appliances and consumer products. A power conditioner is described which is capable to provide the considered waveforms. Finally some measurements have been taken to illustrate the performance of alternative distribution systems.

	RADIATED AND CONDUCTED INTERFERENCES IN INDUCTION HEATING EQUIPMENT: CHARACTERISTICS AND REMEDIES By J. Nuns; H. Foch; M. Metz; X. Yang	[View] [Download]
Abstract: This paper describes all the disturbances resulting from induction heating equipment, and practical methods to deal with the problems in order that induction heating processes can handle disturbances by themselves, and be made more cost-effective. After a great number of measurements and a detail study to a lot of industrial installations, principal mechanisms of the interferences have been revealed. For harmonic distortion, useful solutions have been proposed, some of which are industrially tested or used by manufacturers. The proposed dual Steinmetz Bridge can thoroughly resolve both capacitor switching problem and harmonic amplification in a non-linear load or in a polluted network. A current type inverter is particularly realized in 'spread' type for the high frequency study. On basis of interference mechanisms, practical solutions such as damping reactor, common mode current bypass, and non-linear snubber have been proposed and confirmed in a 'compacted' type inverter. The best way for attenuating the interferences is to dispose at sources and transform them into thermal energy. By understanding mechanism, we can always find some pre-measures to deal with the problems, which are undoubtedly cheaper than that of post-remedies.

	THE PREDICTION OF SUPPLY CURRENT WAVEFORMS AND HARMONICS FOR RECTIFIER CIRCUITS WITH CAPACITIVE SMOOTHING By J. C. Clare; R. M. Davis	[View] [Download]
Abstract: Most equipment using capacitively smoothed rectification will shortly be subject to regulations limiting the allowable amplitudes of supply current harmonics. A method for rapidly computing the harmonic amplitudes based on an analytical function for the current waveform is presented. The analysis includes supply inductance and resistance and the effects of non-infinite dc aide smoothing capacitance. The use of supply side impedance to control harmonic content is discussed and quantitative results for a range of load powers are given.