Hybrid direct current link system for a regenerative drive

• US 10,218,262 B1
• Filed: 09/25/2017
• Issued: 02/26/2019
• Est. Priority Date: 09/25/2017
• Status: Active Grant

• Current Assignee: Otis Elevator Company (Otis Worldwide Corp.)
• Original Assignee: Otis Elevator Company (Otis Worldwide Corp.)
• Inventors: Agirman, Ismail
• Primary Examiner(s): Gblende, Jeffrey A
• Application Number:
  US15/713,829
• Time in Patent Office: 519 Days
• Field of Search: None
• CPC Class Codes: B66B 1/30 effective on driving gear , e.g. acting on power electronics, on inverter or rectifier controlled motor
• CPC Class Codes: H02M 1/00 Details of apparatus for conversion
• CPC Class Codes: H02M 1/4216 operating from a three-phase input voltage H02M1/4233 takes precedence
• CPC Class Codes: H02M 5/00 Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
• CPC Class Codes: H02M 5/40 with intermediate conversion into dc
• CPC Class Codes: H02M 7/00 Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
• CPC Class Codes: H02M 7/04 by static converters
• CPC Class Codes: H02M 7/12 using discharge tubes with control electrode or semiconductor devices with control electrode
• CPC Class Codes: H02M 7/68 by static converters
• CPC Class Codes: H02P 27/06 using dc to ac converters or inverters H02P27/05 takes precedence
• CPC Class Codes: H02P 27/085 wherein the PWM mode is adapted on the running conditions of the motor, e.g. the switching frequency
• CPC Class Codes: H02P 5/46 for speed regulation of two or more dynamo-electric motors in relation to one another

Abstract

A system includes a converter operatively connected to an alternating current (AC) power source and a direct current (DC) bus, an inverter operatively connected to a motor and the DC bus, and a hybrid DC link system operatively connected between a high side and a low side of the DC bus. The converter includes a first plurality of switching devices in selective communication with each phase of the AC power source and the DC bus. The inverter includes a second plurality of switching devices in selective communication with each phase of the motor and the DC bus. The hybrid DC link system includes a ripple current control branch in parallel with an energy buffering branch.

Claims

1. A system, comprising:

a converter operatively connected to an alternating current (AC) power source and a direct current (DC) bus, the converter comprising a first plurality of switching devices in selective communication with each phase of the AC power source and the DC bus;

an inverter operatively connected to a motor and the DC bus, the inverter comprising a second plurality of switching devices in selective communication with each phase of the motor and the DC bus; and

a hybrid DC link system operatively connected between a high side and a low side of the DC bus, the hybrid DC link system comprising a ripple current control branch in parallel with an energy buffering branch, wherein;

the ripple current control branch comprises at least one film capacitor connected between the high side and the low side of the DC bus; and

the energy buffering branch comprises;

one or more electrolytic capacitors with an impedance element between the high side and the low side of the DC bus; and

a first resistor in parallel with a first electrolytic capacitor of the one or more electrolytic capacitors and a second resistor in series with the first resistor and parallel with a second electrolytic capacitor of the one or more electrolytic capacitors.

2. The system of claim 1, wherein a resistance of the first resistor is substantially equal to the resistance of the second resistor, and a capacitance of the first electrolytic capacitor is substantially equal to the capacitance of the second electrolytic capacitor.

3. The system of claim 1, wherein the impedance element comprises an inductor in series with a damping resistive element.

4. The system of claim 3, wherein the damping resistive element comprises an external resistor.

5. The system of claim 3, wherein the damping resistive element comprises a resistance integrated with the inductor.

6. The system of claim 3, wherein the damping resistive element comprises a resistance integrated with at least one of the one or more electrolytic capacitors.

7. The system of claim 1, further comprising a controller operable to transition the system to a fail-safe state based on one or more of:

exceeding a maximum current rating in the hybrid DC link system and exceeding an imbalance limit in the hybrid DC link system.

8. A method comprising:

operably connecting a converter to an alternating current (AC) power source and a direct current (DC) bus, the converter comprising a first plurality of switching devices in selective communication with each phase of the AC power source and the DC bus;

operably connecting an inverter to a motor and the DC bus, the inverter comprising a second plurality of switching devices in selective communication with each phase of the motor and the DC bus;

operably connecting a hybrid DC link system between a high side and a low side of the DC bus, the hybrid DC link system comprising a ripple current control branch in parallel with an energy buffering branch, wherein;

the ripple current control branch comprises at least one film capacitor connected between the high side and the low side of the DC bus; and

the energy buffering branch comprises;

one or more electrolytic capacitors with an impedance element between the high side and the low side of the DC bus; and

a first resistor in parallel with a first electrolytic capacitor of the one or more electrolytic capacitors and a second resistor in series with the first resistor and parallel with a second electrolytic capacitor of the one or more electrolytic capacitors;

limiting a ripple current on the DC bus through the ripple current control branch of the hybrid DC link system; and

buffering variations in energy of the DC bus through the energy buffering branch of the hybrid DC link system.

9. The method of claim 8, wherein a resistance of the first resistor is substantially equal to the resistance of the second resistor, and a capacitance of the first electrolytic capacitor is substantially equal to the capacitance of the second electrolytic capacitor.

10. The method of claim 8, wherein the impedance element comprises an inductor in series with a damping resistive element.

11. The method of claim 10, wherein the damping resistive element comprises an external resistor.

12. The method of claim 10, wherein the damping resistive element comprises a resistance integrated with the inductor.

13. The method of claim 10, wherein the damping resistive element comprises a resistance integrated with at least one of the one or more electrolytic capacitors.

14. The method of claim 8, further comprising:

transitioning, by a controller, a regenerative drive system comprising the converter and the inverter to a fail-safe state based on one or more of;

detecting, by the controller, an exceedance of a maximum current rating in the hybrid DC link system and detecting, by the controller, an exceedance of an imbalance limit in the hybrid DC link system.