Electric power conversion systems – Current conversion – Including an a.c.-d.c.-a.c. converter
Patent
1998-09-14
1999-09-07
Berhane, Adolf Deneke
Electric power conversion systems
Current conversion
Including an a.c.-d.c.-a.c. converter
307 66, H02M 545, H02J 700
Patent
active
059496622
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an uninterruptable power supply device.
BACKGROUND INFORMATION
An uninterruptable power supply device is commercially available and is described, for example, in the Siemens Prospectus "Statische unterbrechungsfreie Stromversorgungen" (Solid-state uninterruptable power supplies) entitled "USV Reihe 42 Leistungsbereich 10 bis 500 kVA" (Series 42 UPS, power range 10 to 500 kVA), Order No. E20001-P161-A4.
FIG. 1 shows a simplified, summary circuit diagram of such an uninterruptable power supply device 2 (UPS device) This UPS device 2 comprises a voltage intermediate circuit converter 4, which includes a component rectifier 6, voltage intermediate circuit 8 and invertor 10. In addition, the UPS device 2 also has the following components: mains commutation inductor L10, mains reset device 12, output filter 14, control device 16 for the converter 4, control device 18 for the mains reset device 12, rectifier input switch Q10, manual bypass switch Q50, mains reset device switch Q51, DC busbar connections C and D, mains connections U1, V1, W1 of the rectifier 6, mains connections U2, V2, W2, N of the mains reset device 12, connections U3, V3, W3, N for a load, connections U4, V4, W4, N for a parallel block, a control panel 20, a monitoring and diagnosis system 22 and remote signalling 24.
A full-wave thyristor three-phase bridge (6-pulse) is provided as the rectifier 6. Optionally, a 12-pulse three-phase bridge can also be provided for the rectifier 6, in order to reduced considerably the mains feedback. For a rating of 500 kVA, the UPS devices are always designed as 12-pulse devices. In the case of the 12-pulse version of the rectifier 6, two balanced 6-pulse three-phase bridges are used, which operate electrically offset through 30.degree. with the aid of a transformer. The control and regulation of the rectifier 6, which is implemented in the converter controller 16, includes the following functions:
software-controlled, battery-conserving automatic charger with IU characteristic and charging current limiting
current limiting to prevent overloading of the rectifier
reduced current limiting and inclined voltage characteristic for operation from a standby mains system
controlled rise: slow voltage and current rise, no inrush current surges
controlled current splitting during parallel operation of two rectifiers in order to prevent nonuniform stresses
staggered rise of the rectifiers in multi-block systems.
The voltage intermediate circuit 8 is designed as a filter circuit. This filter circuit comprises two inductors L11 and a capacitor C20. The two inductors L11 are each integrated in a DC busbar. This filter circuit reduces the natural ripple on the DC voltage and eliminates any voltage spikes. The intermediate circuit voltage is smoothed, and the ripple on the battery current becomes very low. This conserves the battery. The "UPS principle" is based on the fact that the intermediate circuit voltage is kept either by the mains system or in the event of its failure--by the battery in a range which makes it possible for the invertor to keep the output voltage constant.
The invertor 10 comprises a transistor bridge circuit which is connected on the output side to the output filter 14 downstream. This output filter 14 comprises a transformer T20 which has high leakage inductance, and filter capacitors C30. Together with the filter capacitors C30, the leakage inductances of the transformer T20 form the three-phase output filter 14, which filters the fundamental out of the pulse-widthmodulated invertor output voltage and thus produces a sinusoidal output voltage with a low distortion factor. The output voltage is regulated by driving the invertor phases using the method of pulse-width modulation (PWM) with a supersinusoid. Because of the high pulse repetition frequency, the regulation can act very quickly (instantaneous value regulation). Since the waveform of the output voltage is in consequence actively influenced, the feedback effects from loads with non-si
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"Simovert Master Drives. Voltage-Source Converter for Three-Phase Drives 6SE70-2,2 to 200 kW," Siemens Catalog DA 65.1, Seimens AG, Division of Drive, Switch and Installation Technology, 1994.*Discussed in International Preliminary Examination Report. Seimens AG, Division of Drive, Switch and Installation Technology, 1994, pp. 1-23.**Described in Specification.
Boldin Detlef
Buttner Karl-Heinz
Fleisch Karl
Humpfner Roland
Berhane Adolf Deneke
Siemens Aktiengesellschaft
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