EPE Association: EPE 1991 - 27 - Session 3.5: POWER SUPPLIES

EPE 1991 - 27 - Session 3.5: POWER SUPPLIES
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1991 - Conference > EPE 1991 - 27 - Session 3.5: POWER SUPPLIES

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   OPTIMIZED OPERATION MODE FOR 3 KW OFF-LINE PRECONDITIONER CIRCUITS
By M. Albach; D. Dambois [View]
[Download]

Abstract: The optimization of a 3 kW ac-dc boost-converter, operating with an input voltage in the range from 85 V to 264 V is presented. The sinusoidal input current is in accordance with the IEC Harmonic Standard 555-2 and the conducted interference voltages are below the limits of VDE 0871 class B. The various operation modes of this converter topology have been investigated carefully, taking into account a lot of parameters, e.g. switching frequency (constant or modulated), choke current (continuous, discontinuous or mixed mode), filter size, efficiency and so on. The final result of this overall optimization procedure is a circuit consisting of two 1.5 kW modules, operated in parallel with a constant switching frequency of 200 kHz and a phase shift of 180°.

   STANDBY POWER SUPPLY (SPS) WITH LOAD-CURRENT HARMONICS NEUTRALIZER
By N. Mohan; E. Persson; B. Ben Banerjee [View]
[Download]

Abstract: There has been a rapid growth in non-linear loads such as personal computers at home and in the office environment. These non-linear loads are a large source of current harmonics on the utility system with well-known adverse effects. At present, various harmonic current standards are being proposed to limit distortion in the current drawn by these non-linear loads. These loads are often critical and require power backup in the event of a utility outage. These factors provided the motivation for combining the features for load-current harmonics neutralization and power backup. This paper reports on the design procedure and the test results of a 120V (rms), 25A (peak), IGBT prototype built for field evaluation. The prototype is designed for use with one or more office computers.

   A MICROCOMPUTER CONTROLLED DC-TYPE UNINTERRUPTIBLE POWER SYSTEM
By J. Peracaula; J. Bordonau; P. Riba [View]
[Download]

Abstract: A non-conventional implementation and operation of an Uninterruptible Power System (UPS) are described in this work. The control circuit is based on a Microprocessor in order to improve the features and performances of the UPS, taking care not only of the control algorithm, bul also of the overall system management and test or the power block and batteries. The power circuit is also non-conventional avoiding intermediate ac blocks and reducing conversion steps and component count. Experimental results show that the efficiency and reliability of this system are improved when compared with others using more conventional structures.

   A CONTROL STRATEGY FOR THE REDUNDANT PARALLEL OPERATION OF AN ENSEMBLE OF STATIC UPS SVSTEMS OF THE PARALLEL TYPE
By A. van der Krans; K. Bouwknegt [View]
[Download]

Abstract: A parallel type Uninterruptible Power Supply (UPS) operates parallel to the mains via an inductor. lt has three fundamental modes of operation: mains operation ( when mains voltage is OK ), emergency operation ( mains failure ), and bypass ( UPS failure ). UPS systems can be connected in parallel on their input and output terminals, for redundancy or system expansion. Problems arise on circulating reactive power, equal load sharing, circulating DC current and the coordination of the states in which each UPS system may be. These problems can be solved by adequate control and a minimum of information that is exchanged between the participating UPS systems.

   STATIC CONVERTERS FOR AUXILIARY POWER SUPPLY SYSTEMS OF ROLLING STOCK
By J. Stabulnieks; L. Latkovskis; J. Shinka [View]
[Download]

Abstract: The advantages of application of high-voltage inverters for auxiliary power supply for rolling stock are indisputable. There are many conceptions for the design of main circuitary of power supply inverter system and, in general, it depends on the input voltage level range and characteristics of the consumers wich may vary as regards exploitation in different countries. Two conceptions for circuitary design of power inverters for use in on-board power supply systems for rolling stock are proposed by authors. In this paper, the features and test results obtained on the railroads in the USSR are described.

   A PWM SINGLE-PHASE RESONANT DC-LINK INVERTER WITH LOW VOLTAGE STRESS FOR UPS APPLICATIONS
By Pedro Donoso Garcia; Ivo Barbi [View]
[Download]

Abstract: This paper presents a Single-Phase Resonant DC-Link inverter, regulated by PWM, for UPS applications, with reduced voltage stress. PWM modulation is based on the resonant cycle interruption, whereas reduction of transistors overvoltage is based on the employment of non-linear resonant capacitor. Theoretical analysis, design procedure, design example and laboratory experimental results are presented. It is demonstrated that sophisticated modulation techniques such as harmonic elimination can be implemented, contributing to reduce the size and weight of the output filter and to improve dynamic response.

   SINGLE PHASE UPS SYSTEM WITH IMPROVED EFFICIENCY AND SINUSOIDAL INPUT CURRENT
By Nándor Burány; Aleksandar Jelic [View]
[Download]

Abstract: A new topology of on line uninterruptible power supply (UPS) system is proposed. The main features of the system are high efficiency and high input power factor. Efficiency is improved by the elimination of the line frequency input and output transformers and reducing the number of converter stages. Power factor correction is obtained by active wave shaping of the input current. By the proposed UPS topology the lead is never supplied from the mains, so amplitude and frequency variations are not transferred from the input to the output. Switching from line operation to battery operation is without static bypass switches and without break in the output power. A laboratory prototype of the UPS system based on the proposed topology is built and tested. Detailed description of the converter stages and the control circuitry is given. The active harmonic filter is modeled using the averaged model of the pulse-width modulated switch. Simulation and experimental results are presented.

   HIGH VOLTAGE PULSE POWER SUPPLY FOR ELECTROSTATIC PRECIPITATORS
By Franco Poletti [View]
[Download]

Abstract: A solid state, high repetition rate power pulse generator has been developped to satisfy ENEL (ltalian Electricity Company) specifications. The main features of the generator are short pulse duration, low switching losses and good pulse shape with limited tail. The pulses are generated by means of four parallel solid state switching stages, working at an intermediate voltage of 4kV, and then raised to the required peak output voltage (60kV) by four step-up power pulse transformers. A novel, lossles circuit has been developped to recover the residual energy at the end of each pulse cycle and special attention has been payed to the reverse flow of energy in case of breakdown in the load. Particular care has also been devoted to the trigger pulse generator for the solid state switches. Preliminary tests on the prototype, with a simulated load, confirm the correctness of the design assumptions while development work continues on thermal and control aspects.

   HIGH PERFORMANCE DIGITAL CONTROL OF UNINTERRUPTABLE POWER SUPPLY (UPS) USING AN APPLICATION SPECIFIC INTEGRATED CIRCUIT (ASIC)
By Edwin Kiel; Walter Schumacher; Jürgen Ehrenberg; Heinz-Hermann Letas; Uwe Schrader-Hausmann [View]
[Download]

Abstract: An application specific integrated circuit (ASIC) has been designed which performs all last control loops of a three phase inverter system. Two major applications are covered by this circuit: uninterruptable power supplies (UPS) and controlled mains rectifiers with sinusoidal line currents. The fully digital circuit includes seven PI-controllers, the sine generation, the interface to the A/D-converters and the PWM generation for the switching signals. lt was fabricated with CMOS gate array technology. The maximum sampling rata of the control loops amounts to 20 kHz; the delay between the measurement of the controlled quantities and the output of the switching signals is 25 μsec including 15 μsec tor the A/D conversion. The calculation time for one PI-controller is 1 μsec. The inverter controller ASIC attains a better performance than newest signalprocessors - and at a lower price. The ASIC is used in a series of static UPS systems achieving excellent dynamic behavior.

   CONTROL OF A THREE PHASE UPS INVERTER WITH UNBALANCED AND NONLINEAR LOAD
By Peter Korondi; Laszlo Nagy; Geza Nemeth [View]
[Download]

Abstract: The paper is concerned with a control system of a three phase sinusoidal output voltage UPS inverter capable of operating with unbalanced and nonlinear (e.g. computer) load. For the sake of short response time for step change of the switched mode load, instantaneous feedback is used. Because of inter dependence of phases, the Park vector is introduced for the 3-phase to 2-phase transformation. The controller keeps the Park vector of the output voltages on a circular path to ensure sinusoidal output waves. The Park vector phase components are controlled in non-ideal sliding mode using a hysteresis relay with an additional zero phase sequence elimination. Simulation and experimental results for a 100 KVA are presented.

   A NOVEL CURRENT AND VOLTAGE REGULATED ENERGY DISCHARGE POWER SUPPLY 200 A, 600 V
By Age Teake Visser [View]
[Download]

Abstract: The fast spill beam extracted from the 1000 GeV particle accelerator at Fermi National Accelerator Laboratory requires two pulsed magnet and power supply systems to steer the beam to the designated experimental area. This beam steering requires a magnetic field integral of 4kGm per magnet for a duration of 4 msec at a rate of one shot per 5 seconds, and limited to 6 shots per 63 seconds. Each shot cannot last any longer than about 100 msec from start to finish. The magnetic field must be constant to within 1 % during each 4 msec spill period. This paper describes an energy discharge type power supply and magnet that meet these requfrements. This unique power supply has two regulators. One regulator preregulates the storage voltage and the other regulates the required peak current. The magnet and power supply design are interwoven to allow the use of easily available commercial parts for the power supply. Power supply and magnet design should always go hand in hand.

   OPTIMAL UNCERTAINTY MANAGEMENT SCHEMES IN DC UPS SYSTEMS AND THEIR NETWORKS
By Teuvo Suntio; Jari Uusitalo [View]
[Download]

Abstract: The fault and maintenance management of the power systems, providing the energy needed to keep the switching systems functioning, is still mainly based on the use of brute force even if there are available intelligent solutions. The situation is, however, changing. One reason for that have been the natural disasters experienced in the USA and Europe, which caused largescale disruption of road and rail transport as well as electricity supplies. The result was deep uncertainty about the capacity of the power systems to keep on functioning, etc. There is also other uncertainty which affects the switching system and is, in fact, the reason to use the uninterruptible power supply ( UPS ) systems. It is the uncertainty of the energy supplying capacity of the public power lines. lt is obvious that only the reserve energy in the batteries and in the engine alternators can reduce it. The physical power system and even the people maintaining it will increase the uncertainty. This paper will study from the conceptual, philosophical and hardware viewpoint how the chosen uncertainty level (i.e. corresponds to the amount of the reserve energy) can be ensured and the additional uncertainties reduced utilizing microcomputer technology and distributed decision making in the DC UPS systems and their networks. In addition, there will be suggested an optimal power system concept for the large power systems based on system module idea.

   A NOVEL BIDIRECTIONAL UPS
By Hui-Yung Chu; Hurng-Liahng Jou; Ching-Lien Huang; Liang-Chuang Wang [View]
[Download]

Abstract: In this paper, a novel UPS topology based on the bidirectional converter is proposed. In the proposed UPS topology, a pre-regulator implemented by a tap-changer autotransformer is used for reducing the variation of mains voltage within +-5%. The transformerless bidirectional converter incorporated a small regulation inductor is only used for fine voltage regulation. It can improve the major shortcomings of the conventional bidirectional UPS. A steady state model is proposed for optimal parareters design. To test the performance of the proposed bidirectional UPS, a prototype is developed and tested.

EPE 1991 - 27 - Session 3.5: POWER SUPPLIES
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1991 - Conference > EPE 1991 - 27 - Session 3.5: POWER SUPPLIES
	[return to parent folder]

	OPTIMIZED OPERATION MODE FOR 3 KW OFF-LINE PRECONDITIONER CIRCUITS By M. Albach; D. Dambois	[View] [Download]
Abstract: The optimization of a 3 kW ac-dc boost-converter, operating with an input voltage in the range from 85 V to 264 V is presented. The sinusoidal input current is in accordance with the IEC Harmonic Standard 555-2 and the conducted interference voltages are below the limits of VDE 0871 class B. The various operation modes of this converter topology have been investigated carefully, taking into account a lot of parameters, e.g. switching frequency (constant or modulated), choke current (continuous, discontinuous or mixed mode), filter size, efficiency and so on. The final result of this overall optimization procedure is a circuit consisting of two 1.5 kW modules, operated in parallel with a constant switching frequency of 200 kHz and a phase shift of 180°.

	STANDBY POWER SUPPLY (SPS) WITH LOAD-CURRENT HARMONICS NEUTRALIZER By N. Mohan; E. Persson; B. Ben Banerjee	[View] [Download]
Abstract: There has been a rapid growth in non-linear loads such as personal computers at home and in the office environment. These non-linear loads are a large source of current harmonics on the utility system with well-known adverse effects. At present, various harmonic current standards are being proposed to limit distortion in the current drawn by these non-linear loads. These loads are often critical and require power backup in the event of a utility outage. These factors provided the motivation for combining the features for load-current harmonics neutralization and power backup. This paper reports on the design procedure and the test results of a 120V (rms), 25A (peak), IGBT prototype built for field evaluation. The prototype is designed for use with one or more office computers.

	A MICROCOMPUTER CONTROLLED DC-TYPE UNINTERRUPTIBLE POWER SYSTEM By J. Peracaula; J. Bordonau; P. Riba	[View] [Download]
Abstract: A non-conventional implementation and operation of an Uninterruptible Power System (UPS) are described in this work. The control circuit is based on a Microprocessor in order to improve the features and performances of the UPS, taking care not only of the control algorithm, bul also of the overall system management and test or the power block and batteries. The power circuit is also non-conventional avoiding intermediate ac blocks and reducing conversion steps and component count. Experimental results show that the efficiency and reliability of this system are improved when compared with others using more conventional structures.

	A CONTROL STRATEGY FOR THE REDUNDANT PARALLEL OPERATION OF AN ENSEMBLE OF STATIC UPS SVSTEMS OF THE PARALLEL TYPE By A. van der Krans; K. Bouwknegt	[View] [Download]
Abstract: A parallel type Uninterruptible Power Supply (UPS) operates parallel to the mains via an inductor. lt has three fundamental modes of operation: mains operation ( when mains voltage is OK ), emergency operation ( mains failure ), and bypass ( UPS failure ). UPS systems can be connected in parallel on their input and output terminals, for redundancy or system expansion. Problems arise on circulating reactive power, equal load sharing, circulating DC current and the coordination of the states in which each UPS system may be. These problems can be solved by adequate control and a minimum of information that is exchanged between the participating UPS systems.

	STATIC CONVERTERS FOR AUXILIARY POWER SUPPLY SYSTEMS OF ROLLING STOCK By J. Stabulnieks; L. Latkovskis; J. Shinka	[View] [Download]
Abstract: The advantages of application of high-voltage inverters for auxiliary power supply for rolling stock are indisputable. There are many conceptions for the design of main circuitary of power supply inverter system and, in general, it depends on the input voltage level range and characteristics of the consumers wich may vary as regards exploitation in different countries. Two conceptions for circuitary design of power inverters for use in on-board power supply systems for rolling stock are proposed by authors. In this paper, the features and test results obtained on the railroads in the USSR are described.

	A PWM SINGLE-PHASE RESONANT DC-LINK INVERTER WITH LOW VOLTAGE STRESS FOR UPS APPLICATIONS By Pedro Donoso Garcia; Ivo Barbi	[View] [Download]
Abstract: This paper presents a Single-Phase Resonant DC-Link inverter, regulated by PWM, for UPS applications, with reduced voltage stress. PWM modulation is based on the resonant cycle interruption, whereas reduction of transistors overvoltage is based on the employment of non-linear resonant capacitor. Theoretical analysis, design procedure, design example and laboratory experimental results are presented. It is demonstrated that sophisticated modulation techniques such as harmonic elimination can be implemented, contributing to reduce the size and weight of the output filter and to improve dynamic response.

	SINGLE PHASE UPS SYSTEM WITH IMPROVED EFFICIENCY AND SINUSOIDAL INPUT CURRENT By Nándor Burány; Aleksandar Jelic	[View] [Download]
Abstract: A new topology of on line uninterruptible power supply (UPS) system is proposed. The main features of the system are high efficiency and high input power factor. Efficiency is improved by the elimination of the line frequency input and output transformers and reducing the number of converter stages. Power factor correction is obtained by active wave shaping of the input current. By the proposed UPS topology the lead is never supplied from the mains, so amplitude and frequency variations are not transferred from the input to the output. Switching from line operation to battery operation is without static bypass switches and without break in the output power. A laboratory prototype of the UPS system based on the proposed topology is built and tested. Detailed description of the converter stages and the control circuitry is given. The active harmonic filter is modeled using the averaged model of the pulse-width modulated switch. Simulation and experimental results are presented.

	HIGH VOLTAGE PULSE POWER SUPPLY FOR ELECTROSTATIC PRECIPITATORS By Franco Poletti	[View] [Download]
Abstract: A solid state, high repetition rate power pulse generator has been developped to satisfy ENEL (ltalian Electricity Company) specifications. The main features of the generator are short pulse duration, low switching losses and good pulse shape with limited tail. The pulses are generated by means of four parallel solid state switching stages, working at an intermediate voltage of 4kV, and then raised to the required peak output voltage (60kV) by four step-up power pulse transformers. A novel, lossles circuit has been developped to recover the residual energy at the end of each pulse cycle and special attention has been payed to the reverse flow of energy in case of breakdown in the load. Particular care has also been devoted to the trigger pulse generator for the solid state switches. Preliminary tests on the prototype, with a simulated load, confirm the correctness of the design assumptions while development work continues on thermal and control aspects.

	HIGH PERFORMANCE DIGITAL CONTROL OF UNINTERRUPTABLE POWER SUPPLY (UPS) USING AN APPLICATION SPECIFIC INTEGRATED CIRCUIT (ASIC) By Edwin Kiel; Walter Schumacher; Jürgen Ehrenberg; Heinz-Hermann Letas; Uwe Schrader-Hausmann	[View] [Download]
Abstract: An application specific integrated circuit (ASIC) has been designed which performs all last control loops of a three phase inverter system. Two major applications are covered by this circuit: uninterruptable power supplies (UPS) and controlled mains rectifiers with sinusoidal line currents. The fully digital circuit includes seven PI-controllers, the sine generation, the interface to the A/D-converters and the PWM generation for the switching signals. lt was fabricated with CMOS gate array technology. The maximum sampling rata of the control loops amounts to 20 kHz; the delay between the measurement of the controlled quantities and the output of the switching signals is 25 μsec including 15 μsec tor the A/D conversion. The calculation time for one PI-controller is 1 μsec. The inverter controller ASIC attains a better performance than newest signalprocessors - and at a lower price. The ASIC is used in a series of static UPS systems achieving excellent dynamic behavior.

	CONTROL OF A THREE PHASE UPS INVERTER WITH UNBALANCED AND NONLINEAR LOAD By Peter Korondi; Laszlo Nagy; Geza Nemeth	[View] [Download]
Abstract: The paper is concerned with a control system of a three phase sinusoidal output voltage UPS inverter capable of operating with unbalanced and nonlinear (e.g. computer) load. For the sake of short response time for step change of the switched mode load, instantaneous feedback is used. Because of inter dependence of phases, the Park vector is introduced for the 3-phase to 2-phase transformation. The controller keeps the Park vector of the output voltages on a circular path to ensure sinusoidal output waves. The Park vector phase components are controlled in non-ideal sliding mode using a hysteresis relay with an additional zero phase sequence elimination. Simulation and experimental results for a 100 KVA are presented.

	A NOVEL CURRENT AND VOLTAGE REGULATED ENERGY DISCHARGE POWER SUPPLY 200 A, 600 V By Age Teake Visser	[View] [Download]
Abstract: The fast spill beam extracted from the 1000 GeV particle accelerator at Fermi National Accelerator Laboratory requires two pulsed magnet and power supply systems to steer the beam to the designated experimental area. This beam steering requires a magnetic field integral of 4kGm per magnet for a duration of 4 msec at a rate of one shot per 5 seconds, and limited to 6 shots per 63 seconds. Each shot cannot last any longer than about 100 msec from start to finish. The magnetic field must be constant to within 1 % during each 4 msec spill period. This paper describes an energy discharge type power supply and magnet that meet these requfrements. This unique power supply has two regulators. One regulator preregulates the storage voltage and the other regulates the required peak current. The magnet and power supply design are interwoven to allow the use of easily available commercial parts for the power supply. Power supply and magnet design should always go hand in hand.

	OPTIMAL UNCERTAINTY MANAGEMENT SCHEMES IN DC UPS SYSTEMS AND THEIR NETWORKS By Teuvo Suntio; Jari Uusitalo	[View] [Download]
Abstract: The fault and maintenance management of the power systems, providing the energy needed to keep the switching systems functioning, is still mainly based on the use of brute force even if there are available intelligent solutions. The situation is, however, changing. One reason for that have been the natural disasters experienced in the USA and Europe, which caused largescale disruption of road and rail transport as well as electricity supplies. The result was deep uncertainty about the capacity of the power systems to keep on functioning, etc. There is also other uncertainty which affects the switching system and is, in fact, the reason to use the uninterruptible power supply ( UPS ) systems. It is the uncertainty of the energy supplying capacity of the public power lines. lt is obvious that only the reserve energy in the batteries and in the engine alternators can reduce it. The physical power system and even the people maintaining it will increase the uncertainty. This paper will study from the conceptual, philosophical and hardware viewpoint how the chosen uncertainty level (i.e. corresponds to the amount of the reserve energy) can be ensured and the additional uncertainties reduced utilizing microcomputer technology and distributed decision making in the DC UPS systems and their networks. In addition, there will be suggested an optimal power system concept for the large power systems based on system module idea.

	A NOVEL BIDIRECTIONAL UPS By Hui-Yung Chu; Hurng-Liahng Jou; Ching-Lien Huang; Liang-Chuang Wang	[View] [Download]
Abstract: In this paper, a novel UPS topology based on the bidirectional converter is proposed. In the proposed UPS topology, a pre-regulator implemented by a tap-changer autotransformer is used for reducing the variation of mains voltage within +-5%. The transformerless bidirectional converter incorporated a small regulation inductor is only used for fine voltage regulation. It can improve the major shortcomings of the conventional bidirectional UPS. A steady state model is proposed for optimal parareters design. To test the performance of the proposed bidirectional UPS, a prototype is developed and tested.