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Power converter activation

IP.com Disclosure Number: IPCOM000248656D
Publication Date: 2016-Dec-22

Publishing Venue

The IP.com Prior Art Database

Abstract

The present invention provides a method for activating an uninterruptible power supply system (100) comprising at least one AC source (102), at least one DC source (104), both arranged at a power supply side (106) of the uninterruptible power supply system (100), a power output (108), arranged at a load side (110) of the uninterruptible power supply system (100), and at least one power converter (112) connecting the power supply side (106) and the load side (110), each power converter (112) comprising a central DC link (114), a power supply side AC/DC converter unit (117), a power supply side DC/DC converter unit (118), a load side DC/AC converter unit (120), all converter units (117, 118, 120) connected to the DC link (114), a bypass unit (122), whereby the bypass unit (122) is switchable to connect/disconnect the power output (108) to/from the power supply side(106), and a load switch (124), which is switchable to connect/disconnect a load (126) to/from the power output (108), comprising the steps of disconnecting the load (126) from the power output (108) using the load switch (124), disconnecting the power output (108) from the power supply side (106) using the bypass unit (122), powering on the power converter (112), re-circulating power from the power supply side (106) through the at least one power converter (112) back to the power supply side (106), until a desired load current level is reached at the output of the load side DC/AC converter unit (120), by controlling the converter units (117, 118, 120) and the bypass unit (122) of the at least one power converter (112), disconnecting the power output (108) from the power supply side (106) using the bypass unit (122), and connecting the load (126) to the power output (108) using the load switch.

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[0001] Description Power converter activation

Technical Field

[0002] The present invention relates to the area of uninterruptible power supply systems. In particular, the present invention relates to the area of activating power converters of uninterruptible power supply systems.

Background Art

[0003] A typical topology of an uninterruptible power supply (UPS) system comprises at least one AC source, at least one DC source, thereby defining a power supply side, and at least one power converter connecting the AC source and the DC source to a load, which is connected at a load side of the UPS system, as required to provide power to the load.

[0004] It is further known in the Art to provide UPS systems, which comprise multiple parallel power converters. The power converters are responsible for converting source power, as provided from the AC source and/or the DC source, into output power as required by the load. Hence, the power converters are typically connected in parallel to the AC source, which powers the load in case of normal operation, and the DC source, which powers the load in case of a failure of the AC source. The AC and DC source can be provided individually for each power converter, or can be provided commonly for groups of power converters or even commonly for all power converters.

[0005] The implementation of the UPS system with multiple parallel converters has many advantages. Amongst others, some of the advantages of a system design with multiple parallel converters are scalability of the UPS system for varying loads and redundancy of converters in case of failure. Furthermore, depending on the actual

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load, converters which are not required can be operated in standby or even shut down to reduce energy consumption of the UPS system.

[0006] The typical design of the power converter comprises a central DC link with different converter units connected thereto. The converter units comprise a power supply side AC/DC converter unit, also referred to as rectifier, a power supply side DC/DC converter unit, also referred to as battery converter, and a load side DC/AC converter unit, also referred to as inverter.

[0007] A typical design of the power converter further comprises a bypass unit, whereby the bypass unit is switchable to connect/disconnect the power output to a AC source, which is provided at the power supply side. Typically, the bypass unit comprises a thyristor, i.e. a switch, to connect/disconnect the power output to the power supply side. The bypass unit can be provided to enable fault clearance in case of load failures, e.g. a short circuit. State of the art power converters also allow parallel operation with the bypass unit with accurate control of currents of the individual converter units. Thus, parallel operation with the bypass unit as an additional power source allows for re- circulation of current provided at the pow...