Systems and methods for improving efficiency of a neutral-point-clamped inverter

Patent metadata

Field	Value
Publication number	US-10778032-B2
Application number	US-201415122831-A
Country	US
Kind code	B2
Filing date	Mar 3, 2014
Priority date	Mar 3, 2014
Publication date	Sep 15, 2020
Grant date	Sep 15, 2020

Abstract

An uninterruptible power system described herein includes a first input and a second input and an AC output. The uninterruptible power system also includes power circuitry coupled to the first input, the second input, and the AC output, the power circuitry including an inverter having a first pair of switching elements including a first switching element and a second switching element and a second pair of switching elements including a third switching element and a fourth switching element, wherein the first switching element, the second switching element, the third switching element and the fourth switching element have an identical voltage rating; and a controller coupled to the second pair of switching elements and configured to control the third switching element and the fourth switching element to prevent occurrence of an overvoltage condition.

First claim

What is claimed is:

1. An uninterruptible power system comprising:
a first input configured to connect to a first power source;
a second input configured to connect to a second power source;
an AC output configured to provide output power derived from at least one of power at the first input and power at the second input, the AC output having a first output terminal and a second output terminal;
power circuitry coupled to the first input, the second input, and the AC output, the power circuitry including an inverter having a first pair of switching elements including a first switching element and a second switching element, wherein the first switching element is coupled to a positive voltage rail and the second switching element is coupled to a negative voltage rail and a second pair of switching elements including a third switching element and a fourth switching element, wherein the third switching element is coupled to the first switching element and the fourth switching element is coupled to the second switching element, the third switching element and the fourth switching element also being coupled to the first output terminal, wherein the first switching element, the second switching element, the third switching element and the fourth switching element have an identical voltage rating; and
a controller coupled to the second pair of switching elements and configured to control the third switching element and the fourth switching element to prevent occurrence of an overvoltage condition, wherein:
the inverter comprises a first resistor and a first diode connected between the first pair of switching elements,
the first resistor and the first diode are further connected to a second resistor and a second diode, and
the second resistor and the second diode are connected between the second pair of switching elements.

2. The system of claim 1 , wherein the system includes the second power source and the second power source includes a battery.

3. The system of claim 1 , wherein the controller is configured to provide a plurality of pulse width modulated control signals to the inverter, and wherein the plurality of pulse width modulated control signals provided by the controller is configured to prevent occurrence of a plurality of overvoltage conditions, and wherein the plurality of overvoltage conditions includes at least one of the following: the first switching element is on while the third switching element is off, the second switching element is on while the fourth switching element is off, the first and the third switching elements or the second and the fourth switching elements simultaneously change their states, an incorrect voltage across the third or the fourth switching elements, a junction capacitance of the third switching element is less than a junction capacitance of the first switching element, or a junction capacitance of the fourth switching element is less than a junction capacitance of the second switching element.

4. The system of claim 1 , wherein the inverter includes an undervoltage-lockout protection circuit coupled to the second pair of switching elements.

5. The system of claim 1 , wherein the connection of the first resistor and the first diode between the first pair of switching elements and to the second resistor and the second diode, wherein the second resistor and the second diode are connected between the second pair of switching elements protects the second pair of switching elements against a varying junction capacitance by equalizing voltage distribution among the second pair of switching elements.

6. An uninterruptible power supply system comprising:
a first input configured to connect to a first power source;
a second input configured to connect to a second power source;
an AC output configured to provide output power derived from at least one of power at the first input and power at the second input, the AC output having a first output terminal and a second output terminal; and
power circuitry coupled to the first input, the second input, and the AC output, the power circuitry including an inverter having a first pair of switching elements including a first switching element and a second switching element, wherein the first switching element is coupled to a positive voltage rail and the second switching element is coupled to a negative voltage rail and a second pair of switching elements including a third switching element and a fourth switching element, wherein the third switching element is coupled to the first switching element and the fourth switching element is coupled to the second switching element, the third switching element and the fourth switching element also being coupled to the first output terminal, wherein the first switching element, the second switching element, the third switching element and the fourth switching element have an identical voltage rating;
the inverter includes an undervoltage-lockout protection circuit coupled to the second pair of switching elements; and
a controller coupled to the second pair of switching elements and configured to control the third switching element and the fourth switching element to prevent occurrence of an overvoltage condition.

7. The UPS system of claim 6 , wherein the system includes the second power source and the second power source includes a battery.

8. The UPS system of claim 6 , wherein the overvoltage condition includes at least one of the following: the first switching element is on while the third switching element is off, the second switching element is on while the fourth switching element is off, the first and the third switching elements or the second and the fourth switching elements simultaneously change their states, an incorrect voltage across the third or the fourth switching elements, a junction capacitance of the third switching element is less than a junction capacitance of the first switching element, or a junction capacitance of the fourth switching element is less than a junction capacitance of the second switching element.

9. The UPS system of claim 6 , wherein the undervoltage-lockout protection circuit includes an isolated power supply, a gate driver chip with undervoltage-lockout protection, a gate drive undervoltage monitoring unit and an optocoupler.

10. The UPS system of claim 6 , wherein the inverter comprises a first resistor and a first diode connected between the first pair of switching elements, wherein the first resistor and the first diode are further connected to a second resistor and a second diode, wherein the second resistor and the second diode are connected between the second pair of switching elements.

11. An uninterruptible power system comprising:
a first input configured to connect to a first power source;
a second input configured to connect to a second power source;
an AC output configured to provide output power derived from at least one of power at the first input and power at the second input, the AC output having a first output terminal and a second output terminal;
power circuitry coupled to the first input, the second input, and the AC output, the power circuitry including an inverter having a first pair of switching elements including a first switching element and a second switching element, wherein the first switching element is coupled to a positive voltage rail and the second switching element is coupled to a negative voltage rail and a second pair of switching elements including a third switching element and a fourth switching element, wherein the third switching element is coupled to the first switching element and the fourth switching element is coupled to the second switching element, the third switching element and the fourth switching

Assignees

• Schneider Electric It Corp

Inventors

• Ghosh Rajesh
• Nielsen Henning Roar
• Klikic Damir

Classifications

• H02M7/04

  by static converters · CPC title

• H02J9/062 Primary

  for AC powered loads · CPC title

• H02M3/04

  by static converters · CPC title

• H02M7/487

  Neutral point clamped inverters · CPC title

• H02M1/32

  Means for protecting converters other than automatic disconnection · CPC title