Title :
Small-Signal Models for Constant-Current Regulated Converters
Author :
Hankaniemi, Mikko ; Suntio, Teuvo
Author_Institution :
Inst. of Power Electron., Tampere Univ. of Technol.
Abstract :
The telecom DC uninterruptible power supply (UPS) systems include a storage battery to ensure the uninterrupted operation of the system during the power outages in the commercial grid system. The storage battery behaves as an ideal DC voltage source with very low internal impedance but needs to be recharged after discharge of its energy. Therefore, the telecom rectifiers taking care of the recharging have to be provided with output overload limiting for protecting them from damage. Typical overload-protection schemes are modified-constant-power and constant-current methods. It has been observed that the crossover frequency of the output-current loop tends to increase even one decade, when the storage battery is connected as a load. In this paper, the dynamical properties of the current-output converter are investigated, and the set of transfers representing the dynamics is developed based both on the state-space averaging method and on the two-port model of the corresponding voltage-output converter. According to the investigations, the observed tendency to increasing crossover frequency can be addressed to the internal dynamics of the converter, which the storage battery invokes into effect. This means that the origin of the problem is an erroneous control design
Keywords :
power convertors; rectifying circuits; secondary cells; state-space methods; telecommunication power supplies; two-port networks; uninterruptible power supplies; UPS systems; commercial grid system; constant-current methods; constant-current regulated converters; crossover frequency; current-output converter; ideal DC voltage source; modified-constant-power; output overload limiting; output-current loop; overload-protection schemes; power outages; small-signal models; state-space averaging method; storage battery; telecom DC uninterruptible power supply systems; telecom rectifiers; two-port model of; voltage-output converter; Batteries; Fault location; Frequency; Impedance; Power system modeling; Power system protection; Rectifiers; Telecommunications; Uninterruptible power systems; Voltage;
Conference_Titel :
IEEE Industrial Electronics, IECON 2006 - 32nd Annual Conference on
Conference_Location :
Paris
Print_ISBN :
1-4244-0390-1
DOI :
10.1109/IECON.2006.347322