Elevator Motor Regenerative Braking Control for Safe Stopping

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Solution Overview

Problem

Elevator brakes face challenges in safely stopping an elevator car, particularly in scenarios where both brakes fail, leading to rapid deceleration and potential discomfort, and existing safety measures are limited in addressing these issues effectively.

Innovation Solution

A method and apparatus utilizing a safety controller to determine vertical position, speed, and acceleration limits for an elevator car, disabling motor power and applying brakes when limits are exceeded, and re-enabling power for smooth stopping, incorporating sensors and a processor to manage braking and motor control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional mechanical brakes are used to stop the elevator car, then the elevator car can be stopped, but the deceleration may become rapid causing discomfort and potential safety issues

Engineering Contradiction:

Improvebrake safetyVSAvoidrapid deceleration discomfort

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the traditional mechanical brake system with an electrical drive-based braking system. The motor controller is configured to control the motor to brake the elevator car by converting the mechanical braking function into an electrical control function, where the motor acts as a generator to provide regenerative braking. This substitution eliminates the need for separate mechanical brakes and provides smoother, more controllable deceleration.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the braking parameter control from fixed mechanical brake force to dynamically adjustable electrical braking torque. The motor controller adjusts the braking parameters (torque, deceleration rate) based on real-time feedback from sensors monitoring car position, speed, and acceleration. This allows the braking process to be optimized for both safety and comfort by controlling the deceleration profile.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If both brakes fail simultaneously, then the elevator car cannot be stopped using traditional brakes, but existing safety measures are limited

Engineering Contradiction:

Improvebrake failure safetyVSAvoidsafety measure flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent merges the braking function into the motor control system itself. The motor controller is configured to perform both drive and brake functions, eliminating the separation between propulsion and braking systems. This integration ensures that the braking capability is inherent in the drive system and cannot fail independently of the motor control, providing a fallback braking mechanism even if traditional brakes fail.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The motor control system provides self-service braking capability. When traditional brakes fail, the motor controller automatically activates regenerative braking using the motor's electromagnetic resistance, without requiring external mechanical brake systems. The system monitors brake status and autonomously switches to alternative braking methods, ensuring continuous braking capability.

Inventive Principle:

Principle #25Self-service

3Reliability

If mechanical brakes with fault-tolerance design are used, then brake reliability is improved, but device complexity increases

Engineering Contradiction:

Improvebrake fault-toleranceVSAvoidbrake system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the braking function from the separate mechanical brake system and integrates it into the motor control system. By taking out the independent mechanical brake components and incorporating the braking capability into the existing motor controller, the system reduces overall complexity while maintaining reliability through the redundant braking pathways provided by the integrated control architecture.

Inventive Principle:

Principle #2Taking out (Extraction)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution enables more graceful and safe stopping of elevator cars, enhancing safety and comfort by preventing rapid deceleration and providing an additional layer of safety in brake failure situations.

Implementation Method 1

the motor controller is configured to control the motor to brake the elevator car in the event that both brakes fail

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The safety controller is configured to determine at least one of a vertical position limit, a speed limit and an acceleration limit for an elevator car

Methodology Applied

Scientific EffectSensor detection:

Data Source

PatentEP2848568B1A method and an elevator for stopping an elevator car using elevator drive

Publication Date: 2022.07.20 KONE OYJ

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AI summary

The invention relates to a method for determining a speed limit or an acceleration limit for an elevator car based on elevator state information comprising at least information on whether the elevator car (104) is being driven or in a floor. Power supply (170) to the motor (M) is disabled and brakes are applied for braking the elevator car. Speed or acceleration of the elevator car is measured, in response to the applying of the brake and the disabling of the power supply to the motor. It is determined whether the speed or the acceleration of the elevator car exceed the respective limits. Thereupon, power supply to the motor is enabled for stabilizing movement of the elevator car.