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AssigneeABB Research Ltd.
InventorsStaffan Norrga, Frans Dijkhuizen, Tomas Jonsson, Thomas Setz
Estimating the term…
A cascaded electric power converter and a method of operating a cascaded electric power converter are disclosed. The cascaded converter includes: a converter cell including a cell capacitor and at least one phase leg having at least two electric valves, the at least one phase leg being connected in parallel to the cell capacitor; and a control system for controlling the switching of the electric valves of the at least one phase leg. The control system is configured to, upon detection of a need to by-pass the converter cell, control the switching of the electric valves in a manner so that the cell capacitor is short circuited via a phase leg, so as to obtain a current surge through the phase leg, thereby creating a permanent current path through the converter cell.
A cascaded electric power converter comprising:
A static var compensator station comprising a cascaded converter which includes
A high-voltage direct current station comprising a cascaded converter which includes
A power transmission system comprising a cascaded converter which includes
A method of by-passing a converter cell in a cascaded electric power converter including a cell capacitor and at least one phase leg connected in parallel to the cell capacitor, wherein the at least one phase leg has at least two series connected electric valves, the at least two electric valves each having a unidirectional switch, the converter cell further comprising a clamping circuit connected so as to limit voltage across the valves while switching off the valves, and a reactor connected in series between the cell capacitor and the at least one phase leg in order to limit peak current upon short-circuiting of the cell capacitor, the method comprising:
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
Using devices of a triode or transistor type requiring continuous application of a control signal: using semiconductor devices only
Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles: physical arrangements or structures of…
Details of apparatus for conversion: means for protecting converters other than automatic disconnection
Converters with outputs that each can have more than two voltages levels: comprising two or more cells, each including a switchable capacitor, the…
About 3 years 5 months of term left · ends 18 Mar 2030 (estimated)
The present invention relates to the field of power electronic converters, and in particular to cascaded power electronic converters.
Power electronic converters including semiconductor valves are widely used to change the character of electrical energy by means of controlling the voltage, current and/or frequency. Power electronic converters are for example increasingly used in power transmission applications, such as in HVDC transmission systems or in static VAR compensation systems for utility or industry grids.
In such applications, it is important that the down time of the converters is reduced to a minimum, since failure of a converter may result in power outages, which can be costly for society as well as for the power provider. Despite efforts to improve the life time and cycling capability of electronic components, fault free operation of such components cannot be guaranteed. Hence, redundancy is an important concept when designing power transmission systems.
FIG. 1A shows an example of a full-bridge converter cell;
FIG. 1B shows an example of a half-bridge converter cell;
FIG. 1C shows another example of a half-bridge converter cell
FIG. 1a illustrates an example of an embodiment of a converter cell 100A, which could for example be used in a cascade converter as shown in FIG. 3a. Converter cell 100A comprises four electric valves 105a-d which are configured to be able to conduct current in both directions and block voltage in one direction. An electric valve 105a-d of FIG. 1a includes a unidirectional switch 11, or switch 11 for short, and an anti-parallel diode 12, where the unidirectional switch 11 can be controlled to switch off, as well as to switch on. The four valves 105a-d are arranged in a full-bridge configuration (also referred to as an H-bridge configuration) comprising two phase legs: Phase leg 120:1, wherein valve 105a and valve 105b are series connected, and phase leg 120:2, wherein valves 105c and valve 105d are series connected. Within a phase leg 120:1 or 120:2, the valves are connected to be able to block voltage in the same direction. The two phase legs 120:1 and 120:2 are connected in parallel with a cell capacitor 110 in a manner so that the two phase legs 120:1 and 120:2 are capable of blocking voltage from the same end of the cell capacitor 110. The voltage across the cell capacitor 110 is here denoted Uc.
Cell terminals X and Y are provided at the midpoint of phase leg 120:1 and 120:2, respectively, i.e. at a point between the two valves 105a & 105b or 105c & 105d. The voltage between the terminals X and Y, denoted Uxy, can take different values, depending on which valves are switched on and switched off according to table 1a.
TABLE 1a Switching states of converter cell 100A of FIG. 1a. Switching state I II III Uxy 0 −Uc +Uc Valve 105a ON/OFF OFF ON Valve 105b OFF/ON ON OFF Valve 105c ON/OFF ON OFF Valve 105d OFF/ON OFF ON