Electric power conversion systems – Current conversion – Having plural converters for single conversion
Patent
1999-06-22
2000-02-01
Han, Y. J.
Electric power conversion systems
Current conversion
Having plural converters for single conversion
363 71, 363 78, H02M 723
Patent
active
060210575
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a converter system in particular for supplying electrical drives with direct current or DC voltage, or with alternating current or with AC voltage at a specially matched frequency or for dynamic power factor correction having at least one converter which has power semiconductors which can be switched on and off.
BACKGROUND INFORMATION
In the case of converters up to medium ratings (power outputs) (1. . . MW), the control and regulation and the power section can be located in one unit. All the connections are then expediently designed as a single signal connection. There are no physically separated power sections.
However, in the case of converters having relatively high ratings and converters in the megawatt range, it is sometimes technically expedient or desirable to separate the control and regulation and the power section. The problem arises, in particular, of driving physically separated power cabinets from one controller and regulator. Conventionally, in these applications, individual signals have been transmitted in cable harnesses, etc. The synchronism of switching the active power devices is thus not a problem since the only delay times which occur are in cables (inductance of cables, etc.) in the ns range.
However, this procedure is subject to various problems. Thus, for example, the costs for a non-integrated control system rise with the complex wiring, since individual wiring is very expensive. Furthermore, testing connections in individual wiring is complex and expensive, since each individual connection must be checked. Because of the high wiring outlays, it is frequently impossible to design this wiring in redundant form, for economic reasons, which leads to the converter failing in the event of failure of a single connection.
The point-to-point connections in conventional converters are copper cables, which results in further problems because of electrical and electromagnetic interference from the outside or from the converter itself. The necessity for the individual cables to be DCdecoupled, in order to avoid earth loops, leads to additional costs for such a converter system.
The object of the present invention is to provide a converter system having converters in the megawatt range, which overcomes the abovementioned problems.
The object is achieved according to the present invention by a converter system having at least one converter which has power semiconductors which can be switched on and/or off semiconductors by adjusting the times at which the power semiconductors are switched on and off, overall current at the output of the converter by suitably controlling the times at which the individual power semiconductors of the converter are switched-on and off, which is physically separated from it and is logically connected to the power semiconductors via at least one bus system, by means of which the desired times at which the individual power semiconductors are switched on and off are adjustable.
It is also advantageous for the automation unit to be physically connected to the converter via at least one, in particular serial, bus system. In this way, it is possible to dispense with the individual point-to-point connections from the automation unit to the power semiconductor. According to the present invention, it is furthermore possible to design the connection between the automation unit and the semiconductors in a redundant manner, since this is possible at an acceptable cost in the physical bus system.
In another embodiment of the present invention level 1 according to ISO standard 7496 is designed as an optical waveguide, which avoids electromagnetic interference at the connection between the automation unit and the converter.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a first embodiment of a converter system according to the present invention.
FIG. 2 shows a second embodiment of the converter system according to the present invention for controlling a motor and having physically separated parallel-connected power sec
REFERENCES:
patent: 5187656 (1993-02-01), Kurakake
patent: 5499177 (1996-03-01), Ichihara
patent: 5847950 (1998-12-01), Bhagwat
patent: 5886890 (1999-03-01), Ishida et al.
*T. Schutze et al., "Low Floor Trams with IGBT-3-level Inverter", Fifth European Conference on Power Electronics and Applications, Sep. 16, 1993.
*D.H.E. Butler et al., "Compensation of a Digitally Controlled Static Power Converter for the Damping of Rolling Mill Torsional Vibration", Conference Record of the 1990 IEEE Industry Applications Society Annual Meeting, Oct. 12, 1990.
*F.R. Vidil et al., New 1675-mm Hot Strip Mill for an Feng Steel Co., Taiwan, Iron & Steel Engineer, Bd. 67, Nr. Nov. 11, 1990.
Linden Wilhelm
Schorrig Hartmut
Han Y. J.
Siemens Aktiengesellschaft
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