3-Level inverter apparatus

• US 6,597,590 B2
• Filed: 03/15/2002
• Issued: 07/22/2003
• Est. Priority Date: 08/03/2001
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kobayashi, Kiyotaka, Ikimi, Takashi
• Primary Examiner(s): Patel, Rajnikant B.
• Application Number:
  US10/097,567
• Publication Number:
  US 20030026118A1
• Time in Patent Office: 494 Days
• Field of Search: 363/132, 363/135, 363/136, 363/137, 363/54, 363/55, 363/56.05, 363/57, 363/58, 363/97, 363/98, 363/125, 363/128, 363/127, 363/141, 363/144
• US Class Current: 363/58
• CPC Class Codes: H02M 1/34 Snubber circuits
• CPC Class Codes: H02M 1/348 Passive dissipative snubbers
• CPC Class Codes: H02M 7/487 Neutral point clamped inverters

Abstract

Switching devices conjointly use snubber circuits without disposing for each switching device and is interposed between a DC neutral point N and a positive terminal plate of a DC power source. A second snubber circuit is interposed between the DC neutral point N and a negative plate terminal of a DC power source. A third snubber circuit is interposed between the DC neutral point N and an AC output terminal O. The snubber circuit suppresses the rise of the voltage when each switching device shifts from ON to OFF. The snubber circuit clamps a voltage applied to the switching device when this voltage exceeds the power source voltage during the process in which the switching device shifts from ON to OFF. The snubber circuit clamps a voltage applied to the switching device or when this voltage exceeds the power source voltage during the process.

Claims

1. A 3-level inverter including:

first to fourth switching devices connected in series with one another with an AC output terminal being the center;

first to fourth rectification devices respectively connected in reverse parallel relation with said first to fourth switching devices;

a fifth rectification device connected to a DC neutral point as a junction point between first and second DC power sources connected in series with each other and to a junction point between said first and second switching devices; and

a sixth rectification device connected to said DC neutral point and to a junction point between said third and fourth switching devices;

said first and third switching devices and said second and fourth switching devices being ON/OFF controlled in a mutual conjugated relation;

said 3-level inverter comprising;

a first snubber circuit for clamping a voltage applied to said first or third switching device when said voltage exceeds a power source voltage during the processing in which said first or third switching device shifts from ON to OFF;

a second snubber circuit for clamping a voltage applied to said second or fourth switching device when said voltage exceeds a power source voltage during the processing in which said second or fourth switching device shifts from ON to OFF; and

a third snubber circuit interposed between said DC neutral point and said AC output terminal, for constituting a charging/discharging circuit.

5. A 3-level inverter according to any of claims 1 to 2, wherein said first to fourth switching devices comprise IGBT or MOSFET.

2. A 3-level inverter including:

first to fourth switching devices connected in series with one another with an AC output terminal being the center;

first to fourth rectification devices respectively connected in reverse parallel relation with said first to fourth switching devices;

a fifth rectification device connected to a DC neutral point as a junction point between first and second DC power sources connected in series with each other and to a junction point between said first and second switching devices; and

a sixth rectification device connected to said DC neutral point and to a junction point between said third fourth switching devices;

one of the ends of said first switching device being connected to a positive plate terminal of said first DC power source;

one of the ends of said fourth switching device being connected to a negative plate terminal of said second DC power source;

said first and third switching devices and said second and fourth switching devices being ON/OFF controlled in a mutual conjugated relation;

said 3-level inverter comprising;

first and second snubber circuits each comprising a series circuit of a capacitor and a resistor as principal components; and

a third snubber circuit comprising a series circuit of a capacitor and a resistor;

wherein said first snubber circuit is connected to a positive plate terminal of said first DC power source and to said DC neutral point, said second snubber circuit is connected to said DC neutral point and a negative plate terminal of said second DC power source, and said third snubber circuit is connected to said DC neutral point and to said AC output terminal.

3. A 3-level inverter according to claim 2, wherein a snubber rectification device is connected in parallel with said resistor of each of said first and second snubber circuits.

4. A 3-level inverter according to claim 3, wherein an anode side of said snubber rectification device of said first snubber circuit is connected to the positive pate terminal of said first DC power source and a cathode side of said snubber rectification device of said second snubber circuit is connected to the negative plate terminal of said second DC power source.