Multi-level inverter with low loss snubbing circuits

• US 5,841,645 A
• Filed: 04/30/1997
• Issued: 11/24/1998
• Est. Priority Date: 06/03/1996
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Sato, Shinji
• Primary Examiner(s): Sterrett, Jeffrey L.
• Application Number:
  US08/841,388
• Time in Patent Office: 573 Days
• Field of Search: 363/430, 363/131, 363/132
• US Class Current: 363/43
• CPC Class Codes: H02M 7/487 Neutral point clamped inverters

Abstract

A multi-level inverter, including an AC output terminal, at least four DC input terminals with different potentials having a first DC input terminal with a maximum potential and a second DC input terminal with a minimum potential, a positive arm connected between the first DC input terminal and the AC output terminal, and a negative arm connected between the second DC input terminal and the AC output terminal. Each of the positive and negative arms is composed of a plurality of series connected switching devices, respectively. The multi-level inverter further includes a plurality of clamp diodes, each connected between one of the DC input terminals other than the first and second DC input terminals and one of the positive and negative arms, respectively, a plurality of first snubber circuits, each composed of a series circuit of a snubber capacitor and a snubber diode and connected in parallel with one of the switching devices, respectively, and a plurality of discharging circuits, each composed of at least a resistor and connected between one of the first snubber circuits and the DC input terminals, respectively.

Claims

1. A multi-level inverter, comprising:

an AC output terminal;

at lease four DC input terminals with different potentials including a first DC input terminal with a maximum potential and a second DC input terminal with a minimum potential;

a positive arm connected between said first DC input terminal and said AC output terminal;

a negative arm connected between said second DC input terminal and said AC output terminal;

each of said positive and negative arms including a plurality of series connected switching devices;

a plurality of clamp diodes, each corresponding to one of said DC input terminals other than said first and second DC input terminals and also corresponding to one of said positive and negative arms, each of the plurality of clamp diodes connected between the corresponding DC input terminal and the corresponding arm;

a plurality of first snubber circuits, each corresponding to one of said switching devices and including a series circuit of a snubber capacitor and a snubber diode and connected in parallel with the corresponding one of said switching devices; and

a plurality of discharging circuits, each corresponding to one of said first snubber circuits and one of said DC input terminals, each of the plurality of discharging circuits including at least a resistor and connected between the corresponding snubber circuit and the corresponding DC input terminals.

2. The multi-level inverter according to claim 1, further comprising:

a plurality of second snubber circuits each corresponding to one of said switching devices, each of said plurality of second snubber circuits composed of a snubber capacitor, a snubber diode and a snubber resistor and connected in parallel with the corresponding switching device.

3. The multi-level inverter according to claim 1 or claim 2, wherein:

each of said discharging circuit further includes a diode.

4. A multi-phase multi-level inverter, comprising:

at least four DC input terminals with different potentials including a first DC input terminal with a maximum potential and a second DC input terminal with a minimum potential;

a plurality of circuit groups, each group including,

an AC output terminal,

a positive arm connected between said first DC input terminal and said AC output terminal,

a negative connected between said first DC terminal said AC,

a negative connected between said second DC terminal and said AC output terminal,

each of said positive and negative arms including a plurality of series connected switching devices;

a plurality of clamp diodes, each corresponding to one of said DC input terminals other than said first and second DC input terminals and also corresponding to one of said positive and negative arms, each of the plurality of clamp diodes connected between the corresponding DC input terminal and the corresponding arm; and

a plurality of first snubber circuits, each corresponding to one of said switching devices and including a series circuit of a snubber capacitor and a snubber diode and connected in parallel with the corresponding one of said switching devices, respectively; and

a plurality of discharging circuits corresponding to said DC input terminals and said first snubber circuits, each of one of said groups of the discharging circuits including at least a resistor and connected between the corresponding first snubber circuit and the corresponding DC input terminal.

5. The multi-phase multi-level inverter according to claim 4, wherein:

each of said groups further includes a plurality of second snubber circuits corresponding to the switching devices of the groups, each of the plurality of second snubber circuits including a snubber capacitor, a snubber diode and a snubber resistor and connected in parallel with the corresponding switching device.

6. A multi-level inverter, comprising:

an AC output terminal;

at least four DC input terminals with different potentials including a first DC input terminal with a maximum potential and a second DC input terminal with a minimum potential;

a positive arm connected between said first DC input terminal and said AC output terminal;

a negative arm connected between said second DC input terminal and said AC output terminal;

each of said positive and negative arms including a plurality of series connected switching devices;

a plurality of clamp diodes, each corresponding to one of said DC input terminals other than said first and second DC input terminals and also corresponding to one of said positive and negative arms, each of the plurality of clamp diodes connected between the corresponding DC input terminal and the corresponding arm;

a plurality of first snubber circuits, each corresponding to one of said switching devices and including a series circuit of a snubber capacitor and a snubber diode and connected in parallel with the corresponding one of said switching devices; and

a plurality of discharging circuits each corresponding to one of said first snubber circuits, each of the discharging circuit including at least a resistor and connected between the corresponding snubber circuit and one of said first second DC input terminals.

7. The multi-level inverter according to claim 6, further comprising:

a plurality of second snubber circuits corresponding to the switching devices, each of the second snubber circuits including a snubber capacitor, a snubber diode and a snubber resistor and connected in parallel with the corresponding switching device.

8. A multi-phase multi-level inverter, comprising:

at least four DC input terminals with different potentials including a first DC input terminal with a maximum potential and a second DC input terminal with a maximum potential and a second DC input terminal with a minimum potential,

a plurality of circuit groups, each group including,

an AC output terminal,

at least four DC input terminals with different potentials including a first DC input terminal with a maximum potential and a second DC input terminal with a minimum potential,

a positive arm connected between said first DC input terminal and said AC output terminal,

a negative arm connected between said second DC input terminal and said AC output terminal,

each of said positive and negative arms including a plurality of series connected switching devices, respectively,

a plurality of clamp diodes, each corresponding to one of said DC input terminals other than said first and second DC input terminals and also corresponding to one of said positive and negative arms, each of the plurality of clamp diodes connected between the corresponding DC input terminal and the corresponding arm, and

a plurality of first snubber circuits, each corresponding to one of said switching devices and including a series circuit of a snubber capacitor and a snubber diode and connected in parallel with the corresponding one of said switching devices, respectively; and

a plurality of discharging circuits each corresponding to one of said first snubber circuits, each of the second snubber circuits including at least a resistor and connected between the corresponding first snubber circuit in one of said groups, and one of said first and second DC input terminals.

9. The multi-phase multi-level inverter according to claim 8, wherein:

each of said groups further includes a plurality of second snubber circuits corresponding to said switching devices, each of said second snubber circuits including a snubber capacitor, a snubber diode and a snubber resistor and connected in parallel with the corresponding switching device.