EPE Association: EPE 1997 – 28: Dialogue Session DS3a: UNINTERRUPTIBLE POWER SUPPLIES (UPS)

EPE 1997 – 28: Dialogue Session DS3a: UNINTERRUPTIBLE POWER SUPPLIES (UPS)
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1997 - Conference > EPE 1997 – 28: Dialogue Session DS3a: UNINTERRUPTIBLE POWER SUPPLIES (UPS)

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   A NOVEL ADAPTIVE HYSTERESIS BAND CURRENT CONTROL USING DSP FOR A PFC ON-LINE UPS
By YU QIN; SHANSHAN DU [View]
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Abstract: Hysteresis current control is one of the simplest and most popular techniques used to achieve unity power factor for an on-line Uninterruptible Power Supply (UPS). However the conventional fixed band hysteresis control has a variable switching frequency which causes serious EMI problems and dead zones in the zero crossings of input current waveforms as well as high stress on power devices. In this paper, the adaptive hysteresis band current control strategy is proposed, where the hysteresis band is controlled in real time as variations of input current , input voltage and output voltage to keep the switching frequency constant at any operation conditions. This novel current control method with a Digital Signal Processor (DSP) implementation is proposed in current control loop of Power Factor Corrected converter (PFC) used in an on-line UPS. The proposed current control technique is verified by simulations and experiments.

   REAL-TIME VOLTAGE CONTROL FOR UNBALANCED UPS
By S. de PABLO; S. LORENZO; J.A. DOMINGUEZ; S. CACERES [View]
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Abstract: An sliding method is proposed to control the inverter of an unbalanced UPS applying a voltage source mode. All phases can be regulated from a common strategy in asymetrical conditions, and the commutation decision is performed in real-time with a low-cost DSP.The PWM frequency is adjusted through an adaptative hysteresis band, computed by the same DSP. Field Orientation theory and Park vector are used to synchronize the inverter to the utility and select the best semiconductor's status at any time. Some simulations are presented.

   CONTROL STRATEGY OF BIDIRECTIONAL UPS WITH THE PERFORMANCE OF ACTIVE POWER FILTER
By Jae-Ho Choi; Je-Hong Kim; Tae-Young Ahn [View]
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Abstract: This paper proposes a new control strategy of bidirectional uninterruptible power supply(UPS) with the performance of active power filter which compensate the harmonics and reactive power. To improve the transient response for the effective compensation in active power filter mode, it is considered that a simple and precise calculation method of the compensation reference current for the harmonics and reactive power compensation. So a novel closed-loop control strategy is used to calculate the reference current. And the current regulated instantaneous voltage control scheme is used in back-up power mode. The system model and control algorithm are described and analyzed, and the system performance is verified by the simulation and experimental results.

   A Feasible High-Performance Single-Phase UPS Incorporating Switched Mode Rectifier with High-Frequency Transformer Link
By K. Hirachi; J. Yoshitsugu; T. Iseki; Y. Arai; M. Nakaoka [View]
[Download]

Abstract: The general purpose of single-phase UPS topologies are indispensable for the considerable reduction of hannonic current components in AC mains as well as realization of unity power factor correction (PFC). In particular, the single phase PFC rectifier with a high-frequency isolation transformer link has some advantages as an electrically-isolated AC!DC conversion circuit for small scale UPS. This UPS is capable of eliminating harmonic currents, leak current components and realizing an isolation between AC input and DC output power stage as well as matching the DC voltage of the PWM inverter by means of incorporating a compact high frequency transformer into high-frequency intermediate state. Three types of isolated PFC rectifiers designed for 2kVA, 3kVA and 5kVA-UPSs are put into the practical uses respectively, as new topology. This paper presents a high frequency link PFC rectifier, its related operating principle and control strategy, together with the steady-state and dynamic state performances of these types of UPS s developed from a practical point of view.

   METHODS OF ESTABLISHING HF-LINK IN SMALL AND MEDIUM SIZE STATIC UPS SYSTEMS
By T. H. Abdelhamid; M. K. Darwish [View]
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Abstract: Several methods of interfacing a dc bus to a critical load, for uninterruptible power supply (UPS) applications, can be employed. In order to minimize the size, weight and cost of the magnetic components, the power conversion is normally achieved through a high-frequency (HF) link. This paper presents and compares between three different schemes for establishing this HF link in the dc-ac converters used in small and medium size UPS systems (less than lkV A). The HF link voltage can be either of a· sinusoidal pulse-width modulated (PWM) type or of a resonant type such that switching loss, switch stresses and EMI can be reduced. Simulation of the three schemes are carried out using PSpice and verified with experimental results for a 350Hz link frequency. The merits and drawbacks of each scheme are also mentioned.

EPE 1997 – 28: Dialogue Session DS3a: UNINTERRUPTIBLE POWER SUPPLIES (UPS)
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1997 - Conference > EPE 1997 – 28: Dialogue Session DS3a: UNINTERRUPTIBLE POWER SUPPLIES (UPS)
	[return to parent folder]

	A NOVEL ADAPTIVE HYSTERESIS BAND CURRENT CONTROL USING DSP FOR A PFC ON-LINE UPS By YU QIN; SHANSHAN DU	[View] [Download]
Abstract: Hysteresis current control is one of the simplest and most popular techniques used to achieve unity power factor for an on-line Uninterruptible Power Supply (UPS). However the conventional fixed band hysteresis control has a variable switching frequency which causes serious EMI problems and dead zones in the zero crossings of input current waveforms as well as high stress on power devices. In this paper, the adaptive hysteresis band current control strategy is proposed, where the hysteresis band is controlled in real time as variations of input current , input voltage and output voltage to keep the switching frequency constant at any operation conditions. This novel current control method with a Digital Signal Processor (DSP) implementation is proposed in current control loop of Power Factor Corrected converter (PFC) used in an on-line UPS. The proposed current control technique is verified by simulations and experiments.

	REAL-TIME VOLTAGE CONTROL FOR UNBALANCED UPS By S. de PABLO; S. LORENZO; J.A. DOMINGUEZ; S. CACERES	[View] [Download]
Abstract: An sliding method is proposed to control the inverter of an unbalanced UPS applying a voltage source mode. All phases can be regulated from a common strategy in asymetrical conditions, and the commutation decision is performed in real-time with a low-cost DSP.The PWM frequency is adjusted through an adaptative hysteresis band, computed by the same DSP. Field Orientation theory and Park vector are used to synchronize the inverter to the utility and select the best semiconductor's status at any time. Some simulations are presented.

	CONTROL STRATEGY OF BIDIRECTIONAL UPS WITH THE PERFORMANCE OF ACTIVE POWER FILTER By Jae-Ho Choi; Je-Hong Kim; Tae-Young Ahn	[View] [Download]
Abstract: This paper proposes a new control strategy of bidirectional uninterruptible power supply(UPS) with the performance of active power filter which compensate the harmonics and reactive power. To improve the transient response for the effective compensation in active power filter mode, it is considered that a simple and precise calculation method of the compensation reference current for the harmonics and reactive power compensation. So a novel closed-loop control strategy is used to calculate the reference current. And the current regulated instantaneous voltage control scheme is used in back-up power mode. The system model and control algorithm are described and analyzed, and the system performance is verified by the simulation and experimental results.

	A Feasible High-Performance Single-Phase UPS Incorporating Switched Mode Rectifier with High-Frequency Transformer Link By K. Hirachi; J. Yoshitsugu; T. Iseki; Y. Arai; M. Nakaoka	[View] [Download]
Abstract: The general purpose of single-phase UPS topologies are indispensable for the considerable reduction of hannonic current components in AC mains as well as realization of unity power factor correction (PFC). In particular, the single phase PFC rectifier with a high-frequency isolation transformer link has some advantages as an electrically-isolated AC!DC conversion circuit for small scale UPS. This UPS is capable of eliminating harmonic currents, leak current components and realizing an isolation between AC input and DC output power stage as well as matching the DC voltage of the PWM inverter by means of incorporating a compact high frequency transformer into high-frequency intermediate state. Three types of isolated PFC rectifiers designed for 2kVA, 3kVA and 5kVA-UPSs are put into the practical uses respectively, as new topology. This paper presents a high frequency link PFC rectifier, its related operating principle and control strategy, together with the steady-state and dynamic state performances of these types of UPS s developed from a practical point of view.

	METHODS OF ESTABLISHING HF-LINK IN SMALL AND MEDIUM SIZE STATIC UPS SYSTEMS By T. H. Abdelhamid; M. K. Darwish	[View] [Download]
Abstract: Several methods of interfacing a dc bus to a critical load, for uninterruptible power supply (UPS) applications, can be employed. In order to minimize the size, weight and cost of the magnetic components, the power conversion is normally achieved through a high-frequency (HF) link. This paper presents and compares between three different schemes for establishing this HF link in the dc-ac converters used in small and medium size UPS systems (less than lkV A). The HF link voltage can be either of a· sinusoidal pulse-width modulated (PWM) type or of a resonant type such that switching loss, switch stresses and EMI can be reduced. Simulation of the three schemes are carried out using PSpice and verified with experimental results for a 350Hz link frequency. The merits and drawbacks of each scheme are also mentioned.