Electronic circuit for converting electrical energy, and a power supply installation making use thereof

• US 5,668,711 A
• Filed: 07/23/1996
• Issued: 09/16/1997
• Est. Priority Date: 12/29/1994
• Status: Expired due to Term

• Current Assignee: Alstom Transport SA (Alstom SA)
• Original Assignee: GEC Alsthom Transport SA (Alstom SA)
• Inventors: Meynard, Thierry, Lavieville, Jean-Paul, Carrere, Philippe
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): Vu, Bao Q.
• Application Number:
  US08/676,393
• Time in Patent Office: 420 Days
• Field of Search: 363/59, 363/60, 363/62, 327/536, 307/109, 307/110
• US Class Current: 363/62
• CPC Class Codes: H02M 7/483 Converters with outputs that each can have more than two voltages levels
• CPC Class Codes: H02M 7/4837 Flying capacitor converters

Abstract

A multilevel converter including, in particular, a capacitor (C1, C2, . . . , Cn) for each of its cells. The capacitors have nominal charge voltages proportional to their respective ranks in the converter. It also includes control means (BT, DA1, . . . , DAn, pe2, . . . , pen) organized to evaluate said voltage of the voltage source (VECn), and whenever it is insufficient, to suspend said nominal operation of the converter (SE) and to act on said switches (T1, T'"'"'1; T2; T'"'"'2; . . . ; Tn, T'"'"'n) in such a manner that initially, while said voltage of the voltage source is being established, it begins by charging all of the capacitors of the converter (C1, C2, . . . , Cn), after which said control means establish said nominal operation of the converter.

Claims

1. A multilevel converter comprising, in particular, between a voltage source (SE) and a current source (C), a succession of controllable switching cells (CL1, CL2, . . . , CLn), each having two switches (T1, T'"'"'1;

T2, T'"'"'2;

. . . ;

Tn, T'"'"'n), with one pole of each of the two switches forming part of a pair of upstream poles and with the other pole of each of the switches forming one of a pair of downstream poles, the pair of downstream poles of an upstream cell being connected to the pair of upstream poles of a downstream cell, and the pair of upstream poles of a first cell (CL1) being connected to said current source (C) while the pair of downstream poles of a last cell (CLn) is connected to said voltage source (SE), the converter further comprising a capacitor (C1, C2, . . . , Cn) for each cell, except that the capacitor of the last cell may be omitted when said voltage source (SE) is suitable for performing the same role, each capacitor being connected between the two poles constituting the pair of downstream poles of the corresponding cell, the converter also comprising control means governing the nominal operation of the converter by acting on the switches of successive cells in such a manner that the two switches of any given cell are always in respective opposite conduction states, such that in response to a cell control signal (CT1, CT2, . . . , CTn) provided by said control means, one of the two switches in a given cell is successively in a first conduction state and then in a second conduction state during a cyclically repeated period, and such that in response to cell control signals that are identical but offset in time by a fraction of said period the switches of successive cells operate respectively in the same manner but offset in time by said fraction of a period, the successive capacitors (C1, C2, . . . , Cn) having respective increasing nominal charge voltages, the nominal charge voltage of the capacitor in each of said cells being equal to the product of a voltage (VE) from said voltage source (SE) multiplied by the reciprocal of the number of cells and by the rank of the cell, the converter being characterized in that it comprises control means (BT, DA1, . . . , DAn, pe2, . . . , pen) organized to evaluate said voltage of the voltage source of the converter (VECn) and as soon as it is less than a determined threshold, to suspend said nominal operation of the converter ( sd) and to act on said switches (T1, T'"'"'1;

T2, T'"'"'2, . . . ;

Tn, T'"'"'n) in such a manner that while said voltage (VE) of the voltage source (SE) has a value lying between zero and a lowest one of said nominal charge voltages, it charges all of the capacitors of the converter, while said voltage of the voltage source exceeds said lowest nominal charge voltage the capacitor (C1) nominally charged to said voltage is taken out of circuit and said voltage of the voltage source continues to charge the capacitors (C2, . . . , Cn) requiring higher nominal charge voltages, while the voltage of the voltage source exceeds the immediately higher nominal charge voltage the capacitor (C2) nominally charged to said voltage is in turn taken out of circuit, with the voltage of the voltage source continuing to charge the other capacitors, and so on, until all of the capacitors of the converter are charged to their respective nominal charge voltages, after which said control means establish said nominal operation of the converter.

2. A converter according to claim 1, characterized in that said control means (BT, DA2, . . . , DAn, pe2, . . . , pen) act on said switches so that for a voltage of the voltage source that is increasing from zero, both switches are initially closed simultaneously in all of the cells (T1, T'"'"'1;

T2, T'"'"'2;

. . . ;

Tn, T'"'"'n), with the exception of the switches of the first cell (T1, T'"'"'1) which are in another state such that the voltage delivered to said load is zero, after which, as said voltage of the voltage source rises, the pairs of switches of successive following cells (T2, T'"'"'2;

. . . ;

Tn, T'"'"'n) are put into said other state, cell after cell.

3. An installation making use of a converter according to claim 1, characterized in that it is organized, where necessary, so that said establishment of the voltage of the voltage source takes place progressively in a manner appropriate to the converter used.