IGBT-controlled thyristor AC/DC converter

• US 6,108,223 A
• Filed: 10/26/1999
• Issued: 08/22/2000
• Est. Priority Date: 10/26/1999
• Status: Expired due to Fees

• Current Assignee: Otis Elevator Company (Otis Worldwide Corp.)
• Original Assignee: Otis Elevator Company (Otis Worldwide Corp.)
• Inventors: Julian, Alexander L., Oriti, Giovanna
• Primary Examiner(s): BERHANE, ADOLF D
• Application Number:
  US09/427,470
• Time in Patent Office: 301 Days
• Field of Search: 363/78, 363/84, 363/87, 363/88, 363/89
• US Class Current: 363/78
• CPC Class Codes: H02M 7/1623 with control circuit
• CPC Class Codes: H02M 7/21 using devices of a triode or transistor type requiring continuous application of a control signal

Abstract

A hybrid diode/thyristor AC/DC converter includes a thyristor bridge (21) poled oppositely to a diode bridge (13), current through the thyristor bridge being controlled by IGBTs (30, 31). A thyristor turn-off circuit (40-42, 45-47) is responsive to turn-off of the IGBT to reverse bias the thyristors, thereby causing them to turn off. The thyristors and IGBTs are controlled (50) in response to voltage (55-57) of and current flowing (51-53) in the AC mains so as to cause the current flowing to or from the AC mains to be more nearly sinusoidal. The hybrid bridge handles application of regenerative power to the AC mains.

Claims

1. A three-phase AC/DC regenerative converter, comprising:

a six-diode bridge having three nodes, each connected through a corresponding input inductor to a corresponding line of a three-phase AC main; and

a capacitor bank connected by a positive rail and a negative rail across said diode bridge for developing a DC voltage across said rails for application to a load;

characterized by the improvement comprising;

a six-thyristor bridge having three nodes, each connected through a corresponding one of said input inductors to a corresponding one of said lines, said thyristors poled for conduction with said AC mains in a direction opposite to that of said diodes;

each side of said thyristor bridge connected to a corresponding one of said rails through a current limiting inductor and an IGBT having a reverse diode in parallel with it, said IGBTs poled for conduction with said AC mains in the same direction as said thyristors;

a pair of thyristor turn-off circuits, each connected from a node between one of said IGBTs and a corresponding one of said limiting inductors to one of said rails other than the rail to which the corresponding IGBT is connected, each responsive to turn-off of the corresponding IGBT for reverse-biasing a thyristor conducting current through the corresponding limiting inductor; and

a gate drive controller responsive to the voltage of each of said lines and to the current flowing in each of said lines for providing turn-on signals to said thyristors and conduction signals to said IGBTs so as to selectively conduct current through said thyristor bridge and said IGBTs in a manner to cause the current in said lines to more nearly approximate sinusoidal current.

2. A converter according to claim 1 wherein:

said turn-off circuits each comprise a capacitor in series with a diode poled to conduct to said one rail.

3. A converter according to claim 2 further comprising:

a resistor in parallel with said capacitor.