EP-4737370-A1 - AN ACTIVE DYNAMIC BRAKING SOLUTION FOR AN ELEVATOR SYSTEM

EP4737370A1EP 4737370 A1EP4737370 A1EP 4737370A1EP-4737370-A1

Abstract

The invention relates to a method for active dynamic braking of an elevator system (100). The method comprising: detecting (310) a dynamic braking situation, obtaining (320) speed data representing a speed of an elevator car (102), and activating (340) an active dynamic braking operation for dynamically braking the movement of the elevator car (102), if the obtained speed data indicates (330) that the speed of the elevator car (102) reaches a predetermined monitoring speed level. The active dynamic braking operation comprises operating a motor inverter (240) of an elevator drive unit (122) of the elevator system (100) by switching high-side switches (250a) and low-side switches (250b) of the motor inverter (240) in a controlled manner so that a rotating field is generated in stator windings of a hoisting motor (230) for dynamically braking the rotation of the hoisting motor (230) and thus the movement of the elevator car (102). The invention relates also to an elevator drive unit (122), an elevator system (100), a computer program (525), and a computer-readable storage medium.

Inventors

VUORIO, Teppo
STOLT, LAURI
NIKANDER, JUHAMATTI

Assignees

KONE Corporation

Dates

Publication Date: 20260506
Application Date: 20241031

Claims (15)

A method for active dynamic braking of an elevator system (100), the method comprising: detecting (310) a dynamic braking situation, obtaining (320) speed data representing a speed of an elevator car (102), and activating (340) an active dynamic braking operation for dynamically braking the movement of the elevator car (102), if the obtained speed data indicates (330) that the speed of the elevator car (102) reaches a predetermined monitoring speed level, wherein the active dynamic braking operation comprises operating a motor inverter (240) of an elevator drive unit (122) of the elevator system (100) by switching high-side switches (250a) and low-side switches (250b) of the motor inverter (240) in a controlled manner so that a rotating field is generated in stator windings of a hoisting motor (230) for dynamically braking the rotation of the hoisting motor (230) and thus the movement of the elevator car (102).
The method according to claim 1 further comprising adjusting (350) a braking torque generated by the hoisting motor (230) so that the speed of the elevator car (102) does not at least exceed an adaptive speed limit value during the active dynamic braking operation, wherein the predetermined monitoring speed level is lower than the adaptive speed limit value.
The method according to claim 2 further comprising: monitoring (410) adequacy of a supply voltage of the elevator drive unit (122) to energize the elevator drive unit (122), wherein the supply voltage of the elevator drive unit (122) is regenerated from the hoisting motor (230); and increasing (430) the adaptive speed limit value, if the monitoring of the adequacy of the supply voltage of the elevator drive unit (122) indicates (420) that the present level of the adaptive speed limit value is not adequate to energize the elevator drive unit (122).
The method according to claim 3, wherein monitoring the adequacy of the supply voltage of the elevator drive unit (122) comprises monitoring at least one of the following: adequacy of the regenerated motor power, and wherein the adaptive speed limit value is increased, if regenerated motor power drops below a minimum power limit; a DC link voltage of the drive unit (122), and wherein the adaptive speed limit value is increased, if the DC link voltage of the drive unit (122) drops below a minimum voltage limit; a magnetization-axis current of the hoisting motor (230), and wherein the adaptive speed limit value is increased, if the magnetization-axis current falls below a minimum current limit.
The method according to any of claims 2 to 4, wherein adjusting (350) the braking torque generated by the hoisting motor (230) comprises operating the high-side switches (250a) and the low-side switches (250b) of the motor inverter (240).
The method according to any of the preceding claims, wherein the dynamic braking situation is one of the following: a manual opening of a hoisting machine brake (116) due to a power failure situation; an inadequate braking force situation upon issuing a hoisting machine brake activation command.
An elevator drive unit (122) of an elevator system (100), wherein the elevator drive unit (122) comprises: a motor inverter (240) connected to stator windings of a hoisting motor (230) of the elevator system (100), wherein the motor inverter (240) has high-side switches (250a) and low-side switches (250b); and a drive controller (210); wherein the drive controller (210) of the elevator drive unit (122) is configured to cause the elevator drive unit (122) to perform: detect a dynamic braking situation, obtain speed data representing a speed of an elevator car (102), and activate an active dynamic braking operation for dynamically braking the movement of the elevator car (102), if the obtained speed data indicates that the speed of the elevator car (102) reaches a predetermined monitoring speed level, wherein the active dynamic braking operation comprises that the drive controller (210) is configured to operate the motor inverter (240) by switching the high-side switches (250a) and the low-side switches (250b) of the motor inverter (240) in a controlled manner so that the rotating field is generated in the stator windings of the hoisting motor (230) for dynamically braking the rotation of the hoisting motor (230) and thus the movement of the elevator car (102).
The elevator drive unit (122) according to claim 7, further configured to adjust a braking torque generated by the hoisting motor (230) so that the speed of the elevator car (102) does not at least exceed an adaptive speed limit value during the active dynamic braking operation, wherein the predetermined monitoring speed level is lower than the adaptive speed limit value.
The elevator drive unit according to claim 8, further configured to: monitor adequacy of a supply voltage of the elevator drive unit (122) to energize the elevator drive unit (122), wherein the supply voltage of the elevator drive unit (122) is regenerated from the hoisting motor (230); and increase the adaptive speed limit value, if the monitoring of the adequacy of the supply voltage of the elevator drive unit (122) indicates that the present level of the adaptive speed limit value is not adequate to energize the elevator drive unit (122).
The elevator drive unit according to claim 9, wherein to monitor the adequacy of the supply voltage of the elevator drive unit (122) the elevator drive unit (122) is configured to monitor at least one of the following: adequacy of the regenerated motor power, and wherein the elevator drive unit (122) is configured to increase the adaptive speed limit value, if the regenerated motor power drops below a minimum power limit; a DC link voltage of the drive unit (122), and wherein the elevator drive unit (122) is configured to increase the adaptive speed limit value, if the DC link voltage of the drive unit (122) drops below a minimum voltage limit; a magnetization-axis current of the hoisting motor (230), and wherein the elevator drive unit (122) is configured to increase the adaptive speed limit value, if the magnetization-axis current falls below a minimum current limit.
The elevator drive unit (122) according to any of claims 8 to 10, wherein the elevator drive unit (122) is configured to operate the high-side switches (250a) and low-side switches (250b) of the motor inverter (240) to adjust the braking torque.
The elevator drive unit according to any of claims 7 to 11, wherein the dynamic braking situation is one of the following: a manual opening of a hoisting machine brake (116) due to a power failure situation; an inadequate braking force situation upon issuing a hoisting machine brake activation command.
An elevator system (100) comprising: an elevator hoisting machine comprising a hoisting motor (230), an elevator car (102) configured to travel along an elevator shaft (104), an elevator car speed measurement system (112) configured to provide speed data representing a speed of the elevator car (102), and an elevator drive unit (122) according to any of claims 7 to 12.
A computer program (525) comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method according to any of claims 1 to 6.
A computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to carry out the method according to any of claims 1 to 6.

Description

TECHNICAL FIELD The invention concerns in general the technical field of elevator systems. Especially the invention concerns an active dynamic braking solution for elevator systems. BACKGROUND Sometimes in elevator systems a hoisting motor of the elevator system is used to generate braking torque outside of a normal operation of the elevator system to perform a braking operation to brake the movement of an elevator car. This braking operation may be needed, for example, when an elevator car having passenger inside it has been stopped between floors due to a power failure. In that case, typically a field technician comes to the elevator site and opens hoisting machine brakes manually to allow the movement of the elevator car by means of gravity. Another case, in which said braking operation may be needed, can occur, if braking force of elevator hoisting machine brakes has been compromised for some reason. For example, an error in conducting an elevator maintenance, such as a misconduct in a brake adjustment process may lead to such a situation, or if foreign matter, such as oil or grease, gets into the braking surfaces. Traditionally, in case of permanent magnet motors said braking operation has been implemented by shorting stator windings of the hoisting motor, such that rotation of the hoisting motor causes electro motive force (EMF) voltage in the windings of the hoisting motor. The short-circuit in turn causes a current flow in the windings creating a motor torque that acts against the rotation of the hoisting motor, and thus brakes the movement of the elevator car. This braking operation is referred to as dynamic braking. The problem with this traditional dynamic braking operation is that it does not necessarily work properly with all various hoisting motor models and with all various load combinations. With some hoisting motor and/or load combinations, the braking torque may not be adequate, and the elevator operation would become unstable (i.e. the elevator races). Consequently, there is a need for an improved dynamic braking, which generates sufficient amount of motor torque with various hoisting motor and/or load combinations, irrespective of the operational condition and environment of the elevator system. SUMMARY The following presents a simplified summary in order to provide basic understanding of some aspects of various invention embodiments. The summary is not an extensive overview of the invention. It is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying embodiments of the invention. An objective of the invention is to present a method, an elevator drive unit, an elevator system, a computer program, and a computer-readable storage medium for active dynamic braking of an elevator system. Another objective of the invention is that the method, the elevator drive unit, the elevator system, the computer program, and the computer-readable storage medium for active dynamic braking of an elevator system enable ensuring that a hoisting motor generates enough power to maintain the active dynamic braking operation to dynamically braking the movement of the elevator car. The objectives of the invention are reached by a method, an elevator drive unit, an elevator system, a computer program, and a computer-readable storage medium as defined by the respective independent claims. According to a first aspect, a method for active dynamic braking of an elevator system is provided, wherein the method comprises: detecting a dynamic braking situation; obtaining speed data representing a speed of an elevator car, and activating an active dynamic braking operation for dynamically braking the movement of the elevator car, if the obtained speed data indicates that the speed of the elevator car reaches a predetermined monitoring speed level; wherein the active dynamic braking operation comprises operating a motor inverter of an elevator drive unit of the elevator system by switching high-side switches and low-side switches of the motor inverter in a controlled manner so that a rotating field is generated in stator windings of a hoisting motor for dynamically braking the rotation of the hoisting motor and thus the movement of the elevator car. The method may further comprise adjusting a braking torque generated by the hoisting motor so that the speed of the elevator car does not at least exceed an adaptive speed limit value during the active dynamic braking operation, wherein the predetermined monitoring speed level may be lower than the adaptive speed limit value. The method may further comprise: monitoring adequacy of a supply voltage of the elevator drive unit to energize the elevator drive unit, wherein the supply voltage of the elevator drive unit may be regenerated from the hoisting motor; and increasing