Elevator braking in a battery powered elevator system

Patent metadata

Field	Value
Publication number	US-9586789-B2
Application number	US-201314911378-A
Country	US
Kind code	B2
Filing date	Aug 13, 2013
Priority date	Aug 13, 2013
Publication date	Mar 7, 2017
Grant date	Mar 7, 2017

Abstract

An elevator system includes a battery; a machine having a motor to impart motion to an elevator car; an inverter having a plurality of switches to convert DC power from the battery to AC power for the machine in a motoring mode; a speed sensor coupled to the machine, the speed sensor to generate a speed signal indicative of machine speed; and a controller to apply braking signals to a group of the switches in a braking mode, the braking signals having a duty cycle in response to the speed signal.

First claim

The invention claimed is:

1. An elevator system comprising:
a battery;
a machine having a motor to impart motion to an elevator car;
an inverter having a plurality of switches to convert DC power from the battery to AC power for the machine in a motoring mode;
a speed sensor coupled to the machine, the speed sensor to generate a speed signal indicative of machine speed; and
a controller to apply braking signals to a group of the switches in a braking mode, the braking signals having a duty cycle in response to the speed signal.

2. The elevator system of claim 1 wherein:
the braking signals have a common duty cycle.

3. The elevator system of claim 1 wherein:
the braking signals have different duty cycles.

4. The elevator system of claim 1 wherein:
the group of switches is a subset of the plurality of switches.

5. The elevator system of claim 1 wherein:
the plurality of switches includes the group of switches and a further group of switches, the further group of switches being non-conductive during the braking mode.

6. The elevator system of claim 5 further comprising:
a first DC link connecting the battery to the further group of switches; and
a second DC link connecting the battery to the group of switches.

7. The elevator system of claim 6 wherein:
the first DC link has a positive DC voltage.

8. The elevator system of claim 1 wherein:
the braking mode is entered upon opening of an elevator safety chain.

9. The elevator system of claim 1 wherein:
the duty cycle of at least one of the braking signals increases with time in braking mode.

10. A method of controlling an elevator system having a machine that imparts motion to an elevator car and a battery, the method comprising:
determining if a braking mode has been entered;
in braking mode, opening a first group of switches that couple the machine to the battery;
detecting a speed signal indicative of speed of the machine; and
applying braking signals to a second group of switches that couple the machine to the battery, the braking signals having a duty cycle in response to the speed signal.

11. The method of claim 10 wherein:
the braking signals have a common duty cycle.

12. The method of claim 10 wherein:
the braking signals have different duty cycles.

13. The method of claim 10 wherein:
the braking mode is entered upon opening of an elevator safety chain.

14. The method of claim 10 wherein:
the duty cycle of at least one of the braking signals increases with time in braking mode.

15. A motor control system comprising:
a battery;
a machine having a motor;
an inverter having a plurality of switches to convert DC power from the battery to AC power for the machine in a motoring mode;
a speed sensor coupled to the machine, the speed sensor to generate a speed signal indicative of machine speed; and
a controller to apply braking signals to a group of the switches in a braking mode, the braking signals having a duty cycle in response to the speed signal.

Assignees

• Otis Elevator Co

Inventors

• Agirman Ismail
• Marvin Daryl J

Classifications

• H02P27/06

  using DC to AC converters or inverters (H02P27/05 takes precedence) · CPC title

• B66B1/32 Primary

  effective on braking devices {, e.g. acting on electrically controlled brakes (brake control H02P, lift brakes per se B66B5/02)} · CPC title

• H02P3/18

  for stopping or slowing an AC motor · CPC title