Power conversion system and method

• US 8,299,732 B2
• Filed: 01/15/2009
• Issued: 10/30/2012
• Est. Priority Date: 01/15/2009
• Status: Active Grant

• Current Assignee: Rockwell Automation Technologies Incorporated (Allen-Bradley Co., Inc.)
• Original Assignee: Rockwell Automation Technologies Incorporated (Allen-Bradley Co., Inc.)
• Inventors: Hoadley, Frederick L., Skibinski, Gary L.
• Primary Examiner(s): Benson, Walter
• Assistant Examiner(s): LUO, DAVID S
• Application Number:
  US12/354,040
• Publication Number:
  US 20100176755A1
• Time in Patent Office: 1,384 Days
• Field of Search: 318/105, 318/34, 318/400.17, 318/400.2, 318/400.26, 318/400.27, 318/400.28
• US Class Current: 318/105
• CPC Class Codes: H02M 5/14 for conversion between circuits of different phase number
• CPC Class Codes: H02P 2201/13 DC-link of current link type, e.g. typically for thyristor bridges, having an inductor in series with rectifier
• CPC Class Codes: H02P 27/06 using dc to ac converters or inverters H02P27/05 takes precedence
• CPC Class Codes: H02P 5/74 controlling two or more ac dynamo-electric motors H02P5/46, H02P5/60 take precedence

Abstract

Power conversion systems and methods are provided for driving a plurality of motor loads, in which an autotransformer receives AC input currents and provides a plurality of multiphase outputs at a non-zero phase angle relative to one another, and the individual multiphase outputs are provided to corresponding motor drives with rectifiers to convert the multiphase outputs to DC electrical power, and inverters to convert the DC power to AC to drive corresponding motor loads.

Claims

1. A power conversion system, comprising:

a multiphase autotransformer, comprising;

an input operative to receive multiphase AC electrical currents from an isolation transformer or a multiphase AC power source, and

an integer number N multiphase outputs, wherein N is greater than 1, each individual output including a set of an integer number M output terminals, wherein M is greater than 2, each individual output being operative to provide multiphase AC output currents at the output terminals, with the AC output currents of each multiphase output being at a non-zero phase angle relative to all other multiphase outputs; and

a plurality of power converters, each individual power converter including;

a DC output, and a multiphase rectifier operatively coupled with one of the multiphase outputs to convert the corresponding AC output currents to provide DC electrical power at the corresponding DC output to power a DC link having a choke, an inductance or a capacitance coupled between the multiphase rectifier and the DC output, the DC outputs of the plurality of power converters being separate from one another.

2. The power conversion system of claim 1, wherein the autotransformer input is a three-phase input operative to receive three-phase AC electrical currents, and wherein the autotransformer outputs are three-phase outputs having three output terminals.

3. The power conversion system of claim 1, wherein each transformer output is a three-phase output having three output terminals, and wherein the multiphase outputs are offset by a phase angle of 120/N degrees.

4. The power conversion system of claim 1, wherein the autotransformer is a non-isolating autotransformer.

5. The power conversion system of claim 1, wherein each individual output of the transformer is operative to provide multiphase AC output currents at the output terminals at a 360/M degree phase relationship to one another.

6. The power conversion system of claim 1, wherein the individual power converters further include an inverter operatively coupled to receive DC power from the DC output and to provide AC output power to an AC load.

7. The power conversion system of claim 6, wherein the individual power converters are motor drives comprising an inverter operatively coupled to receive DC power from the DC output and to provide AC output power to an AC motor load.

8. The power conversion system of claim 1, wherein the multiphase rectifiers are passive rectifiers.

9. The power conversion system of claim 8, wherein the autotransformer outputs are three-phase outputs having three output terminals, and wherein the multiphase rectifiers are passive rectifiers including six diodes forming a three-phase rectifier bridge.

10. The power conversion system of claim 9, wherein the individual power converters are motor drives comprising an inverter operatively coupled to receive DC power from the DC output and to provide AC output power to an AC motor load.

11. The power conversion system of claim 10, wherein the autotransformer is a non-isolating autotransformer, the system further including an isolation transformer receiving AC input power from a power source and providing the multiphase AC electrical currents to the input of the autotransformer.

12. The power conversion system of claim 8, further including an isolation transformer receiving AC input power from a power source and providing the multiphase AC electrical currents to the input of the autotransformer.

13. The power conversion system of claim 1, further including an isolation transformer receiving AC input power from a power source and providing the multiphase AC electrical currents to the input of the autotransformer.

14. The power conversion system of claim 13, wherein the isolation transformer provides an integer number K output phases, K being an integer greater than 1.

15. The power conversion system of claim 1, wherein at least one of the plurality of power converters includes an SCR rectifier circuit.

16. The power conversion system of claim 1, wherein at least one of the plurality of power converters includes a diode rectifier circuit.

17. The power conversion system of claim 1, wherein at least one of the plurality of power converters includes an IGBT rectifier circuit.

18. A method for driving multiple AC motors, the method comprising:

using a multiphase autotransformer having an integer number N multiphase outputs (N>

1) with each multiphase output including a set of an integer number M output terminals (M>

2), transforming multiphase AC electrical currents from an isolation transformer or a multiphase AC power source to create N sets of multiphase AC output currents, each set of multiphase AC output currents being at a non-zero phase angle relative to all other sets;

rectifying each individual set of multiphase AC output currents to create a corresponding DC bus to power a DC link for the DC bus having a choke, an inductance or a capacitance coupled between a multiphase rectifier and the DC output; and

inverting each individual DC bus to provide AC output power to a corresponding one of a plurality of AC motor loads.

19. The method of claim 18, further comprising isolating the multiphase AC electrical currents from an AC input power source.

20. The method of claim 18, wherein transforming the multiphase AC electrical currents comprises creating two or more sets of three-phase output currents.

21. The method of claim 20, wherein transforming the multiphase AC electrical currents comprises creating N sets of three-phase AC output currents, and wherein the N sets of three-phase AC output currents are offset by a phase angle of 120/N degrees.

22. The method of claim 18, wherein the N sets of multiphase AC output currents are offset by a phase angle of 120/N degrees.

23. The method of claim 18, wherein each individual set of multiphase AC output currents includes M AC output currents at a 360/M degree phase relationship to one another.

24. The method of claim 18, wherein rectifying each individual set of multiphase AC output currents to create a corresponding DC bus comprises providing each individual set of multiphase AC output currents to a corresponding passive rectifier to create a corresponding DC bus.

25. A power conversion system, comprising:

a multiphase autotransformer comprising;

an input operative to receive multiphase AC electrical currents from an isolation transformer or a multiphase AC power source, and

an integer number N multiphase outputs, wherein And is greater than 1, each individual output including a set of an integer number M output terminals, wherein M is greater than 2, each individual output being operative to provide multiphase AC output currents at the output terminals, with the AC output currents of each multiphase output being at a non-zero phase angle relative to all other multiphase outputs; and

a plurality of power converters, each individual power converter including;

a DC output, and

a multiphase rectifier operatively coupled with one of the multiphase outputs to convert the corresponding AC output currents to provide DC electrical power at the corresponding DC output to power a DC link having a choke, an inductance or a capacitance coupled between the multiphase rectifier and the DC output, the DC outputs of the plurality of power converters being separate from one another;

wherein at least one of the power converters includes an inverter operatively coupled to receive DC power from the corresponding DC output and to provide AC output power to an AC motor load.