PARALLEL POWER INVERTER MOTOR DRIVE SYSTEM

• US 20120013283A1
• Filed: 07/16/2010
• Published: 01/19/2012
• Est. Priority Date: 07/16/2010
• Status: Active Grant

• Current Assignee: Rockwell Automation Technologies Incorporated (Allen-Bradley Co., Inc.)
• Original Assignee: Rockwell Automation Technologies Incorporated (Allen-Bradley Co., Inc.)
• Inventors: Tallam, Rangarajan M., Kerkman, Russel J., Radosevich, Richard H., Campbell, Alan J.
• Granted Patent: US 8,188,694 B2
• Time in Patent Office: Days
• US Class Current: 318/400.26
• CPC Class Codes: H02M 5/4585 having a rectifier with controlled elements

Abstract

Multiple inverter motor drives are interconnected in parallel to provide a common output to a motor. Common control circuitry is coupled to all parallel drives via optical cables and provides signals to power layer circuitry of each inverter for generation, at the power layer, of timing for gate drive signals for the respective inverter power electronic switches. The resulting timing exhibits a high degree of synchronicity such that very little imbalance occurs in the outputs of the paralleled drives, resulting in very low circulating currents.

Claims

1. An electric motor drive system comprising:

a plurality of drive modules each comprising a converter for converting incoming AC power to DC power and an inverter coupled to the converter for converting the DC power to controlled frequency AC power;

a shared line-side bus coupled to the converters of the drive modules for providing the incoming AC power;

a shared load-side bus coupled to the inverters for combining the controlled frequency AC power from all of the drive modules into a common AC output; and

a common controller coupled to all of the inverters and configured to provide signals to the inverters to permit each inverter to generate gate drive signals for power electronic switches of the respective inverter separately and in parallel with one another.

2. The system of claim 1, wherein each inverter comprises power layer processing circuitry that, during operation, receives the signals from the common controller and generates timing for the gate drive signals based upon the received signals.

3. The system of claim 2, wherein the power layer processing circuitry of each inverter receives signals from the common control circuitry sufficient for computing a carrier waveform and duty-cycles of the power electronic switches for three phases of output power.

4. The system of claim 3, wherein the signals from the common control circuitry comprise a triangular carrier waveform increment, a deadtime, and output phase compare values.

5. The system of claim 1, wherein the control circuitry is coupled to the inverters via parallel optical cables.

6. The system of claim 5, wherein the optical cables have substantially the same length.

7. The system of claim 5, wherein the optical cables each include only 2 parallel optical fibers.

8. The system of claim 7, wherein one of the optical fibers is dedicated to transmission of data from the common control circuitry to the respective inverter, and the other of the optical fibers is dedicated to transmission of data from the respective inverter to the common control circuitry.

9. The system of claim 5, wherein the optical cables each include only 3 parallel optical fibers.

10. The system of claim 9, wherein a first of the optical fibers is dedicated to transmission of data from the common control circuitry to the respective inverter, a second the other of the optical fibers is dedicated to transmission of data from the respective inverter to the common control circuitry, and a third of the optical fibers is dedicated to providing a clock signal from the common control circuitry to the respective inverter.

11. The system of claim 1, wherein the controlled frequency AC power from all of the drive modules is combined into a common AC output directly via the shared load-side bus without interposition of inductive components therebetween.

12. An electric motor drive system comprising:

a plurality of drive modules each comprising a converter for converting incoming AC power to DC power and an inverter coupled to the converter for converting the DC power to controlled frequency AC power;

a common controller coupled to all of the inverters and configured to provide signals to the inverters to permit each inverter to generate gate drive signals for power electronic switches of the respective inverter separately and in parallel with one another;

a shared line-side bus coupled to the converters of the drive modules for providing the incoming AC power; and

a shared load-side bus coupled to the inverters for combining the controlled frequency AC power from all of the drive modules into a common AC output without interposition of inductive components therebetween;

wherein each inverter comprises power layer processing circuitry that, during operation, receives the signals from the common controller and generates timing for the gate drive signals based upon the received signals.

13. The system of claim 12, wherein the control circuitry is coupled to the inverters via parallel optical cables of substantially equal length.

14. The system of claim 13, wherein the optical cables each include only 2 parallel optical fibers, one of the optical fibers being dedicated to transmission of data from the common control circuitry to the respective inverter, and the other of the optical fibers being dedicated to transmission of data from the respective inverter to the common control circuitry.

15. The system of claim 12, wherein the power layer processing circuitry of each inverter receives signals from the common control circuitry sufficient for computing a carrier waveform and duty-cycles of the power electronic switches for three phases of output power.

16. The system of claim 15, wherein the signals from the common control circuitry comprise a triangular carrier waveform increment, a deadtime, and output phase compare values.

17. An electric motor drive system comprising:

a plurality of drive modules each comprising a converter for converting incoming AC power to DC power and an inverter coupled to the converter for converting the DC power to controlled frequency AC power;

a common controller coupled to all of the inverters and configured to provide signals to the inverters to permit each inverter to generate gate drive signals for power electronic switches of the respective inverter separately and in parallel with one another;

a shared line-side bus coupled to the converters of the drive modules for providing the incoming AC power; and

a shared load-side bus coupled to the inverters for combining the controlled frequency AC power from all of the drive modules into a common AC output without interposition of inductive components therebetween;

wherein each inverter is coupled to the common control circuitry via a respective optical cable and comprises power layer processing circuitry that, during operation, receives the signals from the common controller via the respective optical cable and generates timing for the gate drive signals based upon the received signals, the timing of the gate drive signals of any two of the inverters differing from one another by not more than 40 ns.

18. The system of claim 17, wherein the optical cables each include only 2 parallel optical fibers, one of the optical fibers being dedicated to transmission of data from the common control circuitry to the respective inverter, and the other of the optical fibers being dedicated to transmission of data from the respective inverter to the common control circuitry.

19. The system of claim 17, wherein the power layer processing circuitry of each inverter receives signals from the common control circuitry sufficient for computing a carrier waveform and duty-cycles of the power electronic switches for three phases of output power.

20. The system of claim 19, wherein the signals from the common control circuitry comprise a triangular carrier waveform increment, a deadtime, and output phase compare values.