OPERATON OF A THREE-PHASE REGENERATIVE DRIVE FROM MIXED DC AND SINGLE PHASE AC POWER SOURCES

• US 20110247900A1
• Filed: 11/21/2008
• Published: 10/13/2011
• Est. Priority Date: 11/21/2008
• Status: Active Grant

• Current Assignee: Otis Elevator Company (Otis Worldwide Corp.)
• Original Assignee: Otis Elevator Company (Otis Worldwide Corp.)
• Inventors: Oggianu, Stella M., Thornton, Robert K., Blasko, Vladimir, Agirman, Ismail
• Granted Patent: US 8,629,637 B2
• Time in Patent Office: Days
• US Class Current: 187/247
• CPC Class Codes: B66B 1/302 for energy saving
• CPC Class Codes: B66B 1/308 with AC powered elevator drive
• CPC Class Codes: H02P 2201/03 AC-DC converter stage controlled to provide a defined DC link voltage general aspects of plural converters in cascade H02M
• CPC Class Codes: H02P 2201/07 DC-DC step-up or step-down converter inserted between the power supply and the inverter supplying the motor, e.g. to control voltage source fluctuations, to vary the motor speed general aspects of plural converters in cascade H02M
• CPC Class Codes: H02P 27/00 Arrangements or methods for the control of AC motors characterised by the kind of supply voltage of two or more motors H02P5/00; of synchronous motors with electronic commutators H02P6/00; of DC motors H02P7/00; of stepping motors H02P8/00
• CPC Class Codes: H02P 27/06 using dc to ac converters or inverters H02P27/05 takes precedence
• CPC Class Codes: H02P 3/14 by regenerative braking

Abstract

A three-phase regenerative drive (20) is operated based upon power from a single-phase AC source (12) and power from a DC source (14). The single-phase AC input power and the DC input power are converted to DC voltage on a DC bus (24) by a three-phase converter (22). DC power is provided from the DC bus (24) to a three-phase inverter having outputs connected to a motor (34). A controller (44) controls operation of the three-phase converter (22) based upon contribution factors of the AC and DC sources (12, 14) during motoring and regeneration. The controller (44) also controls an AC component of current from the DC source to reduce ripple current on the DC bus (24).

Claims

1. A three-phase regenerative drive comprising:

a three-phase converter having inputs for connection to a single-phase AC source and a DC source;

a three-phase inverter for connection to a motor;

a DC bus connected between the three-phase converter and the three-phase inverter; and

a controller for providing control signals to the three-phase converter to control respective contributions to current demand by the single-phase AC source and the DC source.

2. The three-phase regenerative drive of claim 1, wherein the three-phase converter comprises:

a first circuit comprising a first set of power transistors for controlling current flow between the single-phase AC source and the DC bus; and

a second circuit comprising a second set of power transistors for controlling current flow between the DC source and the DC bus.

3. The three-phase regenerative drive of claim 2, wherein the control signals include a first set of pulse width modulation (PWM) signals to control the first set of power transistors and a second set of pulse width modulation (PWM) signals to control the second set of power transistors.

4. The three-phase regenerative drive of claim 3, wherein the controller comprises:

a voltage regulator for producing a current reference as a function of DC bus voltage and a reference voltage;

a reference splitter for splitting the current reference into a first reference associated with the single-phase AC source and a second reference associated with the DC source;

an AC current control for generating an AC current control signal based on the first reference;

a first PWM generator for generating the first set of PWM signals as a function of the AC current control signal;

a DC current control for generating a DC current control signal based on the second reference; and

a second PWM generator for generating the second set of PWM signals as a function of the DC current control signal.

5. The three-phase regenerative drive of claim 4 and further comprising:

a current sensor for producing a feedback signal as a function of sensed current flow between the DC source and the DC bus; and

wherein the DC current control generates the DC current control signal based upon the second reference and the feedback signal.

6. The three-phase regenerative drive of claim 5 wherein the controller further comprises:

a ripple regulator for producing a ripple correction signal as a function of DC bus voltage ripple; and

wherein the DC current control generates the DC current control signal based upon the second reference, the feedback signal, and the ripple correction signal.

7. The three-phase regenerative drive of claim 4 and further comprising:

a circuit for producing a feed forward signal as a function of an AC component of current flow from the DC source; and

a signal combiner for modifying the second reference based upon the feed forward signal.

8. The three-phase regenerative drive of claim 4 and further comprising:

a state-of-charge control for providing a charge control signal based upon state-of-charge of the DC source and current flow between the DC source and the DC bus; and

a signal combiner for modifying the second reference based upon the charge control signal.

9. The three-phase regenerative drive of claim 4 wherein the reference splitter splits the current reference based upon a contribution factor.

10. The three-phase regenerative drive of claim 9 wherein the contribution factor is selectable as a function of mode of operation of the three-phase regenerative drive.

11. The three-phase regenerative drive of claim 9 wherein the contribution factor is selectable as a function of at least one of capability of the single-phase AC source, capability of the DC source, capability of components of the three-phase converter and the three-phase inverter, state-of-charge of the DC source, elevator traffic profiles, and utility rates.

12. A method of operative a regenerative drive comprising a converter, an inverter and a DC bus connected between the converter and the inverter, the method comprising:

connecting a single-phase AC source and a DC source to the converter;

creating a current reference as a function of DC bus voltage;

splitting the current reference into a first reference and a second reference;

controlling current flow in the converter between the single-phase AC source and the DC bus as a function of the first reference; and

controlling current flow in the converter between the DC source and the DC bus as a function of the second reference.

13. The method of claim 12 wherein splitting the current reference is based upon a contribution factor.

14. The method of claim 13 wherein the contribution factor is a function of whether the regenerative drive is in a motoring mode, an idle mode, or a regeneration mode.

15. The method of claim 13 wherein the contribution factor is selectable based upon at least one of capability of the single-phase AC source, capability of the DC source, capability of components of the converter and inverter, state-of-charge of the DC source, and utility rates.

16. The method of claim 12 and further comprising:

producing a ripple correction signal as a function of DC bus voltage ripple; and

modifying current flow between the DC source and the DC bus based on the ripple correction signal.

17. The method of claim 12 and further comprising:

producing a feed forward signal as a function of an AC component of current flow from the DC source; and

modifying the second reference based upon the feed forward signal.

18. The method of claim 12 and further comprising:

producing a charge control signal as a function of state of charge of the DC source; and

modifying the second reference based upon the charge control signal.

19. The method of claim 12 and further comprising:

determining power demand on the regenerative drive; and

splitting the current reference so that the first reference is equal to the current reference and the second reference is zero when the power demand is less than a threshold value.

20. The method of claim 12 wherein the inverter is connected to an elevator hoist motor.