System and method for integrating energy storage into modular power converter

Patent metadata

Field	Value
Publication number	US-10243370-B2
Application number	US-201514960729-A
Country	US
Kind code	B2
Filing date	Dec 7, 2015
Priority date	Dec 7, 2015
Publication date	Mar 26, 2019
Grant date	Mar 26, 2019

Abstract

A system for integrating energy storage into a modular power converter includes at least one energy storage unit coupled to a first converter for converting a first direct current (DC) voltage of the at least one energy storage unit into a first high frequency alternating current (AC) voltage. At least three phase legs of the modular power converter generate three phase AC voltages. Each phase leg includes a plurality of switching modules connected in series. The switching modules have a plurality of fully controllable semiconductor switches, an energy storage device, and a second converter coupled to the respective energy storage device for converting a second DC voltage of the energy storage device into a second high frequency AC voltage. In the system, three similarly positioned switching modules of the three phase legs form one power unit. Further, a high frequency transformer is provided which has at least one primary winding connected to the first converter and at least three secondary windings, each connected to the second converter of each of the three similarly positioned switching modules. A controller is configured to regulate at least one electrical parameter of the modular power converter.

First claim

The invention claimed is:

1. A system for integrating energy storage into a modular power converter, the system comprising:
at least one energy storage unit coupled to a first converter for converting a first direct current (DC) voltage of the at least one energy storage unit into a first high frequency alternating current (AC) voltage;
at least three phase legs for the modular power converter for generating three phase AC voltages, each phase leg comprising:
a plurality of switching modules connected in series, each switching module includes:
a plurality of fully controllable semiconductor switches,
an energy storage device,
a second converter coupled to the respective energy storage device for converting a second DC voltage of the energy storage device into a second high frequency AC voltage,

wherein three similarly positioned switching modules of the three phase legs form one power unit;
a high frequency transformer having only one primary winding connected to the first converter and at least three secondary windings, each connected to the second converter of each of the three similarly positioned switching modules; and
a controller configured to regulate at least one electrical parameter of the modular power converter.

2. The system of claim 1 , wherein the at least one energy storage unit includes batteries, supercapacitors, flywheels or fuel cells.

3. The system of claim 1 , wherein the first converter and second converter comprise full bridge converters having two legs, each including two fully controllable semiconductor switches whose terminals are connected in series.

4. The system of claim 1 , wherein the fully controllable semiconductor switches include an insulated gate bipolar transistor (IGBT), a metal oxide semiconductor field effect transistor (MOSFET), a field effect transistor (FET), a gate turn-off thyristor, an insulated gate commutated thyristor (IGCT), an injection enhanced gate transistor (IEGT), a silicon carbide based switch, a gallium nitride based switch, a gallium arsenide based switch, or equivalents thereof.

5. The system of claim 1 , wherein the terminals of fully controllable semiconductor switches are connected in series to connect the plurality of switching modules in series.

6. The system of claim 1 , wherein the controller is further configured to regulate voltages of energy storage devices by interchanging energy of energy storage devices and at least one energy storage unit by way of controlling the first and the second converters.

7. The system of claim 1 , wherein the controller is further configured to isolate the first and second converters in case of a fault.

8. The system of claim 1 , wherein a winding turns ration between the primary winding and the at least three secondary windings is determined based on system requirement.

9. The system of claim 1 , wherein the frequency of the first and the second high frequency AC voltage is higher than 5 kHz.

10. The system of claim 1 , wherein the at least one electrical parameter of the modular power converter includes output current, output voltage, output power of the modular power converter or voltage of the energy storage device.

11. The system of claim 1 , wherein the high frequency transformer cancels out an AC ripple current in the at least one energy storage unit caused due to AC currents in three phase legs.

12. The system of claim 1 , wherein the at least one energy storage unit is electrically grounded or floated.

13. The system of claim 1 , wherein the first and the second converters include half bridge converters.

14. The system of claim 1 , wherein the three phase legs are part of a modular multilevel converter.

15. The system of claim 14 , wherein the end terminals of phase legs are connected together to form a positive DC bus and a negative DC bus.

16. The system of claim 15 , wherein the plurality of switching modules in each phase leg form a first arm and a second arm connected to each other via inductors.

17. The system of claim 15 , wherein the plurality of switching modules in each phase leg form a first arm and a second arm connected to each other via inductors.

18. The system of claim 1 , wherein the three phase legs are part of a flexible AC transmission system (FACTs) device.

19. The system of claim 18 , wherein the one end terminals of phase legs are connected together to form floating bus and other end terminals provide three phase output AC terminals.

20. A method for integrating energy storage into a modular power converter, the method comprising:
coupling at least one energy storage unit to a first converter, wherein the first converter converts a first direct current (DC) voltage of the energy storage unit into a first high frequency alternating current (AC) voltage;
generating three phase AC voltages from at least three phase legs of the modular power converter, each phase leg including a plurality of switching modules connected in series, wherein each of the switching module includes a plurality of fully controllable semiconductor switches, an energy storage device and a second converter coupled to the respective energy storage device for converting a second DC voltage of the energy storage device into a second high frequency AC voltage;
forming one power unit from the three similarly positioned switching modules of the three phase legs;
providing a high frequency transformer having only one primary winding and at least three secondary windings between the power unit and the first power converter, wherein the primary winding is connected to the first power converter and each of the three secondary windings is connected to the second converter of each of the three similarly positioned switching modules; and
regulating at least one electrical parameter of the modular power converter.

21. The method of claim 20 , wherein the at least one energy storage unit includes batteries, flywheels, supercapacitors, or fuel cells.

22. The method of claim 20 , wherein the first converter and second converter comprise full bridge converters or half bridge converters or combinations thereof.

23. The method of claim 20 further comprising regulating voltages of energy storage devices by interchanging energy of energy storage devices and energy storage unit via the first and the second converters.

24. The method of claim 20 , wherein the phase legs are part of a modular multilevel converter or a flexible AC transmission system device.

25. The method of claim 20 wherein both end terminals of phase legs are connected together to form a positive DC bus or a negative DC bus or one end terminals of phase legs are connected together to form a floating bus and another end terminals form three phase AC output terminals.

Assignees

• Gen Electric

Inventors

• Garces Luis Jose
• Zhou Rui
• Zhou Zhi
• Zhang Di

Classifications

• H02J3/30

  using dynamo-electric machines coupled to flywheels · CPC title

• H02M1/15

  using active elements · CPC title

• Y02E60/16

  Mechanical energy storage, e.g. flywheels or pressurised fluids · CPC title

• H02J2101/30

  Fuel cells · CPC title

• H02J3/32 Primary

  using batteries or super capacitors with converting means · CPC title